Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: (55 commits)
  workqueue: mark init_workqueues() as early_initcall()
  workqueue: explain for_each_*cwq_cpu() iterators
  fscache: fix build on !CONFIG_SYSCTL
  slow-work: kill it
  gfs2: use workqueue instead of slow-work
  drm: use workqueue instead of slow-work
  cifs: use workqueue instead of slow-work
  fscache: drop references to slow-work
  fscache: convert operation to use workqueue instead of slow-work
  fscache: convert object to use workqueue instead of slow-work
  workqueue: fix how cpu number is stored in work->data
  workqueue: fix mayday_mask handling on UP
  workqueue: fix build problem on !CONFIG_SMP
  workqueue: fix locking in retry path of maybe_create_worker()
  async: use workqueue for worker pool
  workqueue: remove WQ_SINGLE_CPU and use WQ_UNBOUND instead
  workqueue: implement unbound workqueue
  workqueue: prepare for WQ_UNBOUND implementation
  libata: take advantage of cmwq and remove concurrency limitations
  workqueue: fix worker management invocation without pending works
  ...

Fixed up conflicts in fs/cifs/* as per Tejun. Other trivial conflicts in
include/linux/workqueue.h, kernel/trace/Kconfig and kernel/workqueue.c

Documentation/filesystems/caching/fscache.txt

@@ -343,8 +343,8 @@ This will look something like:
 	[root@andromeda ~]# head /proc/fs/fscache/objects
 	OBJECT   PARENT   STAT CHLDN OPS OOP IPR EX READS EM EV F S | NETFS_COOKIE_DEF TY FL NETFS_DATA       OBJECT_KEY, AUX_DATA
 	======== ======== ==== ===== === === === == ===== == == = = | ================ == == ================ ================
-	   17e4b        2 ACTV     0   0   0   0  0     0 7b  4 0 8 | NFS.fh           DT  0 ffff88001dd82820 010006017edcf8bbc93b43298fdfbe71e50b57b13a172c0117f38472, e567634700000000000000000000000063f2404a000000000000000000000000c9030000000000000000000063f2404a
-	   1693a        2 ACTV     0   0   0   0  0     0 7b  4 0 8 | NFS.fh           DT  0 ffff88002db23380 010006017edcf8bbc93b43298fdfbe71e50b57b1e0162c01a2df0ea6, 420ebc4a000000000000000000000000420ebc4a0000000000000000000000000e1801000000000000000000420ebc4a
+	   17e4b        2 ACTV     0   0   0   0  0     0 7b  4 0 0 | NFS.fh           DT  0 ffff88001dd82820 010006017edcf8bbc93b43298fdfbe71e50b57b13a172c0117f38472, e567634700000000000000000000000063f2404a000000000000000000000000c9030000000000000000000063f2404a
+	   1693a        2 ACTV     0   0   0   0  0     0 7b  4 0 0 | NFS.fh           DT  0 ffff88002db23380 010006017edcf8bbc93b43298fdfbe71e50b57b1e0162c01a2df0ea6, 420ebc4a000000000000000000000000420ebc4a0000000000000000000000000e1801000000000000000000420ebc4a
 
 where the first set of columns before the '|' describe the object:
 
@@ -362,7 +362,7 @@ where the first set of columns before the '|' describe the object:
 	EM	Object's event mask
 	EV	Events raised on this object
 	F	Object flags
-	S	Object slow-work work item flags
+	S	Object work item busy state mask (1:pending 2:running)
 
 and the second set of columns describe the object's cookie, if present:
 
@@ -395,8 +395,8 @@ and the following paired letters:
 	w	Show objects that don't have pending writes
 	R	Show objects that have outstanding reads
 	r	Show objects that don't have outstanding reads
-	S	Show objects that have slow work queued
-	s	Show objects that don't have slow work queued
+	S	Show objects that have work queued
+	s	Show objects that don't have work queued
 
 If neither side of a letter pair is given, then both are implied.  For example:
 

Documentation/slow-work.txt

@@ -1,322 +0,0 @@
-		     ====================================
-		     SLOW WORK ITEM EXECUTION THREAD POOL
-		     ====================================
-
-By: David Howells <dhowells@redhat.com>
-
-The slow work item execution thread pool is a pool of threads for performing
-things that take a relatively long time, such as making mkdir calls.
-Typically, when processing something, these items will spend a lot of time
-blocking a thread on I/O, thus making that thread unavailable for doing other
-work.
-
-The standard workqueue model is unsuitable for this class of work item as that
-limits the owner to a single thread or a single thread per CPU.  For some
-tasks, however, more threads - or fewer - are required.
-
-There is just one pool per system.  It contains no threads unless something
-wants to use it - and that something must register its interest first.  When
-the pool is active, the number of threads it contains is dynamic, varying
-between a maximum and minimum setting, depending on the load.
-
-
-====================
-CLASSES OF WORK ITEM
-====================
-
-This pool support two classes of work items:
-
- (*) Slow work items.
-
- (*) Very slow work items.
-
-The former are expected to finish much quicker than the latter.
-
-An operation of the very slow class may do a batch combination of several
-lookups, mkdirs, and a create for instance.
-
-An operation of the ordinarily slow class may, for example, write stuff or
-expand files, provided the time taken to do so isn't too long.
-
-Operations of both types may sleep during execution, thus tying up the thread
-loaned to it.
-
-A further class of work item is available, based on the slow work item class:
-
- (*) Delayed slow work items.
-
-These are slow work items that have a timer to defer queueing of the item for
-a while.
-
-
-THREAD-TO-CLASS ALLOCATION
---------------------------
-
-Not all the threads in the pool are available to work on very slow work items.
-The number will be between one and one fewer than the number of active threads.
-This is configurable (see the "Pool Configuration" section).
-
-All the threads are available to work on ordinarily slow work items, but a
-percentage of the threads will prefer to work on very slow work items.
-
-The configuration ensures that at least one thread will be available to work on
-very slow work items, and at least one thread will be available that won't work
-on very slow work items at all.
-
-
-=====================
-USING SLOW WORK ITEMS
-=====================
-
-Firstly, a module or subsystem wanting to make use of slow work items must
-register its interest:
-
-	 int ret = slow_work_register_user(struct module *module);
-
-This will return 0 if successful, or a -ve error upon failure.  The module
-pointer should be the module interested in using this facility (almost
-certainly THIS_MODULE).
-
-
-Slow work items may then be set up by:
-
- (1) Declaring a slow_work struct type variable:
-
-	#include <linux/slow-work.h>
-
-	struct slow_work myitem;
-
- (2) Declaring the operations to be used for this item:
-
-	struct slow_work_ops myitem_ops = {
-		.get_ref = myitem_get_ref,
-		.put_ref = myitem_put_ref,
-		.execute = myitem_execute,
-	};
-
-     [*] For a description of the ops, see section "Item Operations".
-
- (3) Initialising the item:
-
-	slow_work_init(&myitem, &myitem_ops);
-
-     or:
-
-	delayed_slow_work_init(&myitem, &myitem_ops);
-
-     or:
-
-	vslow_work_init(&myitem, &myitem_ops);
-
-     depending on its class.
-
-A suitably set up work item can then be enqueued for processing:
-
-	int ret = slow_work_enqueue(&myitem);
-
-This will return a -ve error if the thread pool is unable to gain a reference
-on the item, 0 otherwise, or (for delayed work):
-
-	int ret = delayed_slow_work_enqueue(&myitem, my_jiffy_delay);
-
-
-The items are reference counted, so there ought to be no need for a flush
-operation.  But as the reference counting is optional, means to cancel
-existing work items are also included:
-
-	cancel_slow_work(&myitem);
-	cancel_delayed_slow_work(&myitem);
-
-can be used to cancel pending work.  The above cancel function waits for
-existing work to have been executed (or prevent execution of them, depending
-on timing).
-
-
-When all a module's slow work items have been processed, and the
-module has no further interest in the facility, it should unregister its
-interest:
-
-	slow_work_unregister_user(struct module *module);
-
-The module pointer is used to wait for all outstanding work items for that
-module before completing the unregistration.  This prevents the put_ref() code
-from being taken away before it completes.  module should almost certainly be
-THIS_MODULE.
-
-
-================
-HELPER FUNCTIONS
-================
-
-The slow-work facility provides a function by which it can be determined
-whether or not an item is queued for later execution:
-
-	bool queued = slow_work_is_queued(struct slow_work *work);
-
-If it returns false, then the item is not on the queue (it may be executing
-with a requeue pending).  This can be used to work out whether an item on which
-another depends is on the queue, thus allowing a dependent item to be queued
-after it.
-
-If the above shows an item on which another depends not to be queued, then the
-owner of the dependent item might need to wait.  However, to avoid locking up
-the threads unnecessarily be sleeping in them, it can make sense under some
-circumstances to return the work item to the queue, thus deferring it until
-some other items have had a chance to make use of the yielded thread.
-
-To yield a thread and defer an item, the work function should simply enqueue
-the work item again and return.  However, this doesn't work if there's nothing
-actually on the queue, as the thread just vacated will jump straight back into
-the item's work function, thus busy waiting on a CPU.
-
-Instead, the item should use the thread to wait for the dependency to go away,
-but rather than using schedule() or schedule_timeout() to sleep, it should use
-the following function:
-
-	bool requeue = slow_work_sleep_till_thread_needed(
-			struct slow_work *work,
-			signed long *_timeout);
-
-This will add a second wait and then sleep, such that it will be woken up if
-either something appears on the queue that could usefully make use of the
-thread - and behind which this item can be queued, or if the event the caller
-set up to wait for happens.  True will be returned if something else appeared
-on the queue and this work function should perhaps return, of false if
-something else woke it up.  The timeout is as for schedule_timeout().
-
-For example:
-
-	wq = bit_waitqueue(&my_flags, MY_BIT);
-	init_wait(&wait);
-	requeue = false;
-	do {
-		prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
-		if (!test_bit(MY_BIT, &my_flags))
-			break;
-		requeue = slow_work_sleep_till_thread_needed(&my_work,
-							     &timeout);
-	} while (timeout > 0 && !requeue);
-	finish_wait(wq, &wait);
-	if (!test_bit(MY_BIT, &my_flags)
-		goto do_my_thing;
-	if (requeue)
-		return; // to slow_work
-
-
-===============
-ITEM OPERATIONS
-===============
-
-Each work item requires a table of operations of type struct slow_work_ops.
-Only ->execute() is required; the getting and putting of a reference and the
-describing of an item are all optional.
-
- (*) Get a reference on an item:
-
-	int (*get_ref)(struct slow_work *work);
-
-     This allows the thread pool to attempt to pin an item by getting a
-     reference on it.  This function should return 0 if the reference was
-     granted, or a -ve error otherwise.  If an error is returned,
-     slow_work_enqueue() will fail.
-
-     The reference is held whilst the item is queued and whilst it is being
-     executed.  The item may then be requeued with the same reference held, or
-     the reference will be released.
-
- (*) Release a reference on an item:
-
-	void (*put_ref)(struct slow_work *work);
-
-     This allows the thread pool to unpin an item by releasing the reference on
-     it.  The thread pool will not touch the item again once this has been
-     called.
-
- (*) Execute an item:
-
-	void (*execute)(struct slow_work *work);
-
-     This should perform the work required of the item.  It may sleep, it may
-     perform disk I/O and it may wait for locks.
-
- (*) View an item through /proc:
-
-	void (*desc)(struct slow_work *work, struct seq_file *m);
-
-     If supplied, this should print to 'm' a small string describing the work
-     the item is to do.  This should be no more than about 40 characters, and
-     shouldn't include a newline character.
-
-     See the 'Viewing executing and queued items' section below.
-
-
-==================
-POOL CONFIGURATION
-==================
-
-The slow-work thread pool has a number of configurables:
-
- (*) /proc/sys/kernel/slow-work/min-threads
-
-     The minimum number of threads that should be in the pool whilst it is in
-     use.  This may be anywhere between 2 and max-threads.
-
- (*) /proc/sys/kernel/slow-work/max-threads
-
-     The maximum number of threads that should in the pool.  This may be
-     anywhere between min-threads and 255 or NR_CPUS * 2, whichever is greater.
-
- (*) /proc/sys/kernel/slow-work/vslow-percentage
-
-     The percentage of active threads in the pool that may be used to execute
-     very slow work items.  This may be between 1 and 99.  The resultant number
-     is bounded to between 1 and one fewer than the number of active threads.
-     This ensures there is always at least one thread that can process very
-     slow work items, and always at least one thread that won't.
-
-
-==================================
-VIEWING EXECUTING AND QUEUED ITEMS
-==================================
-
-If CONFIG_SLOW_WORK_DEBUG is enabled, a debugfs file is made available:
-
-	/sys/kernel/debug/slow_work/runqueue
-
-through which the list of work items being executed and the queues of items to
-be executed may be viewed.  The owner of a work item is given the chance to
-add some information of its own.
-
-The contents look something like the following:
-
-    THR PID   ITEM ADDR        FL MARK  DESC
-    === ===== ================ == ===== ==========
-      0  3005 ffff880023f52348  a 952ms FSC: OBJ17d3: LOOK
-      1  3006 ffff880024e33668  2 160ms FSC: OBJ17e5 OP60d3b: Write1/Store fl=2
-      2  3165 ffff8800296dd180  a 424ms FSC: OBJ17e4: LOOK
-      3  4089 ffff8800262c8d78  a 212ms FSC: OBJ17ea: CRTN
-      4  4090 ffff88002792bed8  2 388ms FSC: OBJ17e8 OP60d36: Write1/Store fl=2
-      5  4092 ffff88002a0ef308  2 388ms FSC: OBJ17e7 OP60d2e: Write1/Store fl=2
-      6  4094 ffff88002abaf4b8  2 132ms FSC: OBJ17e2 OP60d4e: Write1/Store fl=2
-      7  4095 ffff88002bb188e0  a 388ms FSC: OBJ17e9: CRTN
-    vsq     - ffff880023d99668  1 308ms FSC: OBJ17e0 OP60f91: Write1/EnQ fl=2
-    vsq     - ffff8800295d1740  1 212ms FSC: OBJ16be OP4d4b6: Write1/EnQ fl=2
-    vsq     - ffff880025ba3308  1 160ms FSC: OBJ179a OP58dec: Write1/EnQ fl=2
-    vsq     - ffff880024ec83e0  1 160ms FSC: OBJ17ae OP599f2: Write1/EnQ fl=2
-    vsq     - ffff880026618e00  1 160ms FSC: OBJ17e6 OP60d33: Write1/EnQ fl=2
-    vsq     - ffff880025a2a4b8  1 132ms FSC: OBJ16a2 OP4d583: Write1/EnQ fl=2
-    vsq     - ffff880023cbe6d8  9 212ms FSC: OBJ17eb: LOOK
-    vsq     - ffff880024d37590  9 212ms FSC: OBJ17ec: LOOK
-    vsq     - ffff880027746cb0  9 212ms FSC: OBJ17ed: LOOK
-    vsq     - ffff880024d37ae8  9 212ms FSC: OBJ17ee: LOOK
-    vsq     - ffff880024d37cb0  9 212ms FSC: OBJ17ef: LOOK
-    vsq     - ffff880025036550  9 212ms FSC: OBJ17f0: LOOK
-    vsq     - ffff8800250368e0  9 212ms FSC: OBJ17f1: LOOK
-    vsq     - ffff880025036aa8  9 212ms FSC: OBJ17f2: LOOK
-
-In the 'THR' column, executing items show the thread they're occupying and
-queued threads indicate which queue they're on.  'PID' shows the process ID of
-a slow-work thread that's executing something.  'FL' shows the work item flags.
-'MARK' indicates how long since an item was queued or began executing.  Lastly,
-the 'DESC' column permits the owner of an item to give some information.
-

arch/ia64/kernel/smpboot.c

@@ -519,7 +519,7 @@ do_boot_cpu (int sapicid, int cpu)
 	/*
 	 * We can't use kernel_thread since we must avoid to reschedule the child.
 	 */
-	if (!keventd_up() || current_is_keventd())
+	if (!keventd_up())
 		c_idle.work.func(&c_idle.work);
 	else {
 		schedule_work(&c_idle.work);

arch/x86/kernel/smpboot.c

@@ -735,7 +735,7 @@ static int __cpuinit do_boot_cpu(int apicid, int cpu)
 		goto do_rest;
 	}
 
-	if (!keventd_up() || current_is_keventd())
+	if (!keventd_up())
 		c_idle.work.func(&c_idle.work);
 	else {
 		schedule_work(&c_idle.work);

drivers/acpi/osl.c

@@ -191,36 +191,11 @@ acpi_status __init acpi_os_initialize(void)
 	return AE_OK;
 }
 
-static void bind_to_cpu0(struct work_struct *work)
-{
-	set_cpus_allowed_ptr(current, cpumask_of(0));
-	kfree(work);
-}
-
-static void bind_workqueue(struct workqueue_struct *wq)
-{
-	struct work_struct *work;
-
-	work = kzalloc(sizeof(struct work_struct), GFP_KERNEL);
-	INIT_WORK(work, bind_to_cpu0);
-	queue_work(wq, work);
-}
-
 acpi_status acpi_os_initialize1(void)
 {
-	/*
-	 * On some machines, a software-initiated SMI causes corruption unless
-	 * the SMI runs on CPU 0.  An SMI can be initiated by any AML, but
-	 * typically it's done in GPE-related methods that are run via
-	 * workqueues, so we can avoid the known corruption cases by binding
-	 * the workqueues to CPU 0.
-	 */
-	kacpid_wq = create_singlethread_workqueue("kacpid");
-	bind_workqueue(kacpid_wq);
-	kacpi_notify_wq = create_singlethread_workqueue("kacpi_notify");
-	bind_workqueue(kacpi_notify_wq);
-	kacpi_hotplug_wq = create_singlethread_workqueue("kacpi_hotplug");
-	bind_workqueue(kacpi_hotplug_wq);
+	kacpid_wq = create_workqueue("kacpid");
+	kacpi_notify_wq = create_workqueue("kacpi_notify");
+	kacpi_hotplug_wq = create_workqueue("kacpi_hotplug");
 	BUG_ON(!kacpid_wq);
 	BUG_ON(!kacpi_notify_wq);
 	BUG_ON(!kacpi_hotplug_wq);
@@ -766,7 +741,14 @@ static acpi_status __acpi_os_execute(acpi_execute_type type,
 	else
 		INIT_WORK(&dpc->work, acpi_os_execute_deferred);
 
-	ret = queue_work(queue, &dpc->work);
+	/*
+	 * On some machines, a software-initiated SMI causes corruption unless
+	 * the SMI runs on CPU 0.  An SMI can be initiated by any AML, but
+	 * typically it's done in GPE-related methods that are run via
+	 * workqueues, so we can avoid the known corruption cases by always
+	 * queueing on CPU 0.
+	 */
+	ret = queue_work_on(0, queue, &dpc->work);
 
 	if (!ret) {
 		printk(KERN_ERR PREFIX

drivers/ata/libata-core.c

@@ -98,8 +98,6 @@ static unsigned long ata_dev_blacklisted(const struct ata_device *dev);
 
 unsigned int ata_print_id = 1;
 
-struct workqueue_struct *ata_aux_wq;
-
 struct ata_force_param {
 	const char	*name;
 	unsigned int	cbl;
@@ -5594,6 +5592,7 @@ struct ata_port *ata_port_alloc(struct ata_host *host)
 	ap->msg_enable = ATA_MSG_DRV | ATA_MSG_ERR | ATA_MSG_WARN;
 #endif
 
+	mutex_init(&ap->scsi_scan_mutex);
 	INIT_DELAYED_WORK(&ap->hotplug_task, ata_scsi_hotplug);
 	INIT_WORK(&ap->scsi_rescan_task, ata_scsi_dev_rescan);
 	INIT_LIST_HEAD(&ap->eh_done_q);
@@ -6532,29 +6531,20 @@ static int __init ata_init(void)
 
 	ata_parse_force_param();
 
-	ata_aux_wq = create_singlethread_workqueue("ata_aux");
-	if (!ata_aux_wq)
-		goto fail;
-
 	rc = ata_sff_init();
-	if (rc)
-		goto fail;
+	if (rc) {
+		kfree(ata_force_tbl);
+		return rc;
+	}
 
 	printk(KERN_DEBUG "libata version " DRV_VERSION " loaded.\n");
 	return 0;
-
-fail:
-	kfree(ata_force_tbl);
-	if (ata_aux_wq)
-		destroy_workqueue(ata_aux_wq);
-	return rc;
 }
 
 static void __exit ata_exit(void)
 {
 	ata_sff_exit();
 	kfree(ata_force_tbl);
-	destroy_workqueue(ata_aux_wq);
 }
 
 subsys_initcall(ata_init);

drivers/ata/libata-eh.c

@@ -727,7 +727,7 @@ void ata_scsi_error(struct Scsi_Host *host)
 	if (ap->pflags & ATA_PFLAG_LOADING)
 		ap->pflags &= ~ATA_PFLAG_LOADING;
 	else if (ap->pflags & ATA_PFLAG_SCSI_HOTPLUG)
-		queue_delayed_work(ata_aux_wq, &ap->hotplug_task, 0);
+		schedule_delayed_work(&ap->hotplug_task, 0);
 
 	if (ap->pflags & ATA_PFLAG_RECOVERED)
 		ata_port_printk(ap, KERN_INFO, "EH complete\n");
@@ -2945,7 +2945,7 @@ static int ata_eh_revalidate_and_attach(struct ata_link *link,
 			ehc->i.flags |= ATA_EHI_SETMODE;
 
 			/* schedule the scsi_rescan_device() here */
-			queue_work(ata_aux_wq, &(ap->scsi_rescan_task));
+			schedule_work(&(ap->scsi_rescan_task));
 		} else if (dev->class == ATA_DEV_UNKNOWN &&
 			   ehc->tries[dev->devno] &&
 			   ata_class_enabled(ehc->classes[dev->devno])) {

drivers/ata/libata-scsi.c

@@ -3435,7 +3435,7 @@ void ata_scsi_scan_host(struct ata_port *ap, int sync)
 				"                  switching to async\n");
 	}
 
-	queue_delayed_work(ata_aux_wq, &ap->hotplug_task,
+	queue_delayed_work(system_long_wq, &ap->hotplug_task,
 			   round_jiffies_relative(HZ));
 }
 
@@ -3582,6 +3582,7 @@ void ata_scsi_hotplug(struct work_struct *work)
 	}
 
 	DPRINTK("ENTER\n");
+	mutex_lock(&ap->scsi_scan_mutex);
 
 	/* Unplug detached devices.  We cannot use link iterator here
 	 * because PMP links have to be scanned even if PMP is
@@ -3595,6 +3596,7 @@ void ata_scsi_hotplug(struct work_struct *work)
 	/* scan for new ones */
 	ata_scsi_scan_host(ap, 0);
 
+	mutex_unlock(&ap->scsi_scan_mutex);
 	DPRINTK("EXIT\n");
 }
 
@@ -3673,9 +3675,7 @@ static int ata_scsi_user_scan(struct Scsi_Host *shost, unsigned int channel,
  *	@work: Pointer to ATA port to perform scsi_rescan_device()
  *
  *	After ATA pass thru (SAT) commands are executed successfully,
- *	libata need to propagate the changes to SCSI layer.  This
- *	function must be executed from ata_aux_wq such that sdev
- *	attach/detach don't race with rescan.
+ *	libata need to propagate the changes to SCSI layer.
  *
  *	LOCKING:
  *	Kernel thread context (may sleep).
@@ -3688,6 +3688,7 @@ void ata_scsi_dev_rescan(struct work_struct *work)
 	struct ata_device *dev;
 	unsigned long flags;
 
+	mutex_lock(&ap->scsi_scan_mutex);
 	spin_lock_irqsave(ap->lock, flags);
 
 	ata_for_each_link(link, ap, EDGE) {
@@ -3707,6 +3708,7 @@ void ata_scsi_dev_rescan(struct work_struct *work)
 	}
 
 	spin_unlock_irqrestore(ap->lock, flags);
+	mutex_unlock(&ap->scsi_scan_mutex);
 }
 
 /**

drivers/ata/libata-sff.c

@@ -3318,14 +3318,7 @@ void ata_sff_port_init(struct ata_port *ap)
 
 int __init ata_sff_init(void)
 {
-	/*
-	 * FIXME: In UP case, there is only one workqueue thread and if you
-	 * have more than one PIO device, latency is bloody awful, with
-	 * occasional multi-second "hiccups" as one PIO device waits for
-	 * another.  It's an ugly wart that users DO occasionally complain
-	 * about; luckily most users have at most one PIO polled device.
-	 */
-	ata_sff_wq = create_workqueue("ata_sff");
+	ata_sff_wq = alloc_workqueue("ata_sff", WQ_RESCUER, WQ_MAX_ACTIVE);
 	if (!ata_sff_wq)
 		return -ENOMEM;
 

drivers/ata/libata.h

@@ -54,7 +54,6 @@ enum {
 };
 
 extern unsigned int ata_print_id;
-extern struct workqueue_struct *ata_aux_wq;
 extern int atapi_passthru16;
 extern int libata_fua;
 extern int libata_noacpi;

drivers/gpu/drm/drm_crtc_helper.c

@@ -831,13 +831,11 @@ int drm_helper_resume_force_mode(struct drm_device *dev)
 }
 EXPORT_SYMBOL(drm_helper_resume_force_mode);
 
-static struct slow_work_ops output_poll_ops;
-
 #define DRM_OUTPUT_POLL_PERIOD (10*HZ)
-static void output_poll_execute(struct slow_work *work)
+static void output_poll_execute(struct work_struct *work)
 {
-	struct delayed_slow_work *delayed_work = container_of(work, struct delayed_slow_work, work);
-	struct drm_device *dev = container_of(delayed_work, struct drm_device, mode_config.output_poll_slow_work);
+	struct delayed_work *delayed_work = to_delayed_work(work);
+	struct drm_device *dev = container_of(delayed_work, struct drm_device, mode_config.output_poll_work);
 	struct drm_connector *connector;
 	enum drm_connector_status old_status, status;
 	bool repoll = false, changed = false;
@@ -877,7 +875,7 @@ static void output_poll_execute(struct slow_work *work)
 	}
 
 	if (repoll) {
-		ret = delayed_slow_work_enqueue(delayed_work, DRM_OUTPUT_POLL_PERIOD);
+		ret = queue_delayed_work(system_nrt_wq, delayed_work, DRM_OUTPUT_POLL_PERIOD);
 		if (ret)
 			DRM_ERROR("delayed enqueue failed %d\n", ret);
 	}
@@ -887,7 +885,7 @@ void drm_kms_helper_poll_disable(struct drm_device *dev)
 {
 	if (!dev->mode_config.poll_enabled)
 		return;
-	delayed_slow_work_cancel(&dev->mode_config.output_poll_slow_work);
+	cancel_delayed_work_sync(&dev->mode_config.output_poll_work);
 }
 EXPORT_SYMBOL(drm_kms_helper_poll_disable);
 
@@ -903,7 +901,7 @@ void drm_kms_helper_poll_enable(struct drm_device *dev)
 	}
 
 	if (poll) {
-		ret = delayed_slow_work_enqueue(&dev->mode_config.output_poll_slow_work, DRM_OUTPUT_POLL_PERIOD);
+		ret = queue_delayed_work(system_nrt_wq, &dev->mode_config.output_poll_work, DRM_OUTPUT_POLL_PERIOD);
 		if (ret)
 			DRM_ERROR("delayed enqueue failed %d\n", ret);
 	}
@@ -912,9 +910,7 @@ EXPORT_SYMBOL(drm_kms_helper_poll_enable);
 
 void drm_kms_helper_poll_init(struct drm_device *dev)
 {
-	slow_work_register_user(THIS_MODULE);
-	delayed_slow_work_init(&dev->mode_config.output_poll_slow_work,
-			       &output_poll_ops);
+	INIT_DELAYED_WORK(&dev->mode_config.output_poll_work, output_poll_execute);
 	dev->mode_config.poll_enabled = true;
 
 	drm_kms_helper_poll_enable(dev);
@@ -924,7 +920,6 @@ EXPORT_SYMBOL(drm_kms_helper_poll_init);
 void drm_kms_helper_poll_fini(struct drm_device *dev)
 {
 	drm_kms_helper_poll_disable(dev);
-	slow_work_unregister_user(THIS_MODULE);
 }
 EXPORT_SYMBOL(drm_kms_helper_poll_fini);
 
@@ -932,12 +927,8 @@ void drm_helper_hpd_irq_event(struct drm_device *dev)
 {
 	if (!dev->mode_config.poll_enabled)
 		return;
-	delayed_slow_work_cancel(&dev->mode_config.output_poll_slow_work);
-	/* schedule a slow work asap */
-	delayed_slow_work_enqueue(&dev->mode_config.output_poll_slow_work, 0);
+	/* kill timer and schedule immediate execution, this doesn't block */
+	cancel_delayed_work(&dev->mode_config.output_poll_work);
+	queue_delayed_work(system_nrt_wq, &dev->mode_config.output_poll_work, 0);
 }
 EXPORT_SYMBOL(drm_helper_hpd_irq_event);
-
-static struct slow_work_ops output_poll_ops = {
-	.execute = output_poll_execute,
-};

drivers/media/video/ivtv/ivtv-driver.c

@@ -705,6 +705,8 @@ done:
  */
 static int __devinit ivtv_init_struct1(struct ivtv *itv)
 {
+	struct sched_param param = { .sched_priority = 99 };
+
 	itv->base_addr = pci_resource_start(itv->pdev, 0);
 	itv->enc_mbox.max_mbox = 2; /* the encoder has 3 mailboxes (0-2) */
 	itv->dec_mbox.max_mbox = 1; /* the decoder has 2 mailboxes (0-1) */
@@ -716,13 +718,17 @@ static int __devinit ivtv_init_struct1(struct ivtv *itv)
 	spin_lock_init(&itv->lock);
 	spin_lock_init(&itv->dma_reg_lock);
 
-	itv->irq_work_queues = create_singlethread_workqueue(itv->v4l2_dev.name);
-	if (itv->irq_work_queues == NULL) {
-		IVTV_ERR("Could not create ivtv workqueue\n");
+	init_kthread_worker(&itv->irq_worker);
+	itv->irq_worker_task = kthread_run(kthread_worker_fn, &itv->irq_worker,
+					   itv->v4l2_dev.name);
+	if (IS_ERR(itv->irq_worker_task)) {
+		IVTV_ERR("Could not create ivtv task\n");
 		return -1;
 	}
+	/* must use the FIFO scheduler as it is realtime sensitive */
+	sched_setscheduler(itv->irq_worker_task, SCHED_FIFO, &param);
 
-	INIT_WORK(&itv->irq_work_queue, ivtv_irq_work_handler);
+	init_kthread_work(&itv->irq_work, ivtv_irq_work_handler);
 
 	/* start counting open_id at 1 */
 	itv->open_id = 1;
@@ -1006,7 +1012,7 @@ static int __devinit ivtv_probe(struct pci_dev *pdev,
 	/* PCI Device Setup */
 	retval = ivtv_setup_pci(itv, pdev, pci_id);
 	if (retval == -EIO)
-		goto free_workqueue;
+		goto free_worker;
 	if (retval == -ENXIO)
 		goto free_mem;
 
@@ -1218,8 +1224,8 @@ free_mem:
 	release_mem_region(itv->base_addr + IVTV_REG_OFFSET, IVTV_REG_SIZE);
 	if (itv->has_cx23415)
 		release_mem_region(itv->base_addr + IVTV_DECODER_OFFSET, IVTV_DECODER_SIZE);
-free_workqueue:
-	destroy_workqueue(itv->irq_work_queues);
+free_worker:
+	kthread_stop(itv->irq_worker_task);
 err:
 	if (retval == 0)
 		retval = -ENODEV;
@@ -1363,9 +1369,9 @@ static void ivtv_remove(struct pci_dev *pdev)
 	ivtv_set_irq_mask(itv, 0xffffffff);
 	del_timer_sync(&itv->dma_timer);
 
-	/* Stop all Work Queues */
-	flush_workqueue(itv->irq_work_queues);
-	destroy_workqueue(itv->irq_work_queues);
+	/* Kill irq worker */
+	flush_kthread_worker(&itv->irq_worker);
+	kthread_stop(itv->irq_worker_task);
 
 	ivtv_streams_cleanup(itv, 1);
 	ivtv_udma_free(itv);

drivers/media/video/ivtv/ivtv-driver.h

@@ -51,7 +51,7 @@
 #include <linux/unistd.h>
 #include <linux/pagemap.h>
 #include <linux/scatterlist.h>
-#include <linux/workqueue.h>
+#include <linux/kthread.h>
 #include <linux/mutex.h>
 #include <linux/slab.h>
 #include <asm/uaccess.h>
@@ -260,7 +260,6 @@ struct ivtv_mailbox_data {
 #define IVTV_F_I_DEC_PAUSED	   20 	/* the decoder is paused */
 #define IVTV_F_I_INITED		   21 	/* set after first open */
 #define IVTV_F_I_FAILED		   22 	/* set if first open failed */
-#define IVTV_F_I_WORK_INITED       23	/* worker thread was initialized */
 
 /* Event notifications */
 #define IVTV_F_I_EV_DEC_STOPPED	   28	/* decoder stopped event */
@@ -666,8 +665,9 @@ struct ivtv {
 	/* Interrupts & DMA */
 	u32 irqmask;                    /* active interrupts */
 	u32 irq_rr_idx;                 /* round-robin stream index */
-	struct workqueue_struct *irq_work_queues;       /* workqueue for PIO/YUV/VBI actions */
-	struct work_struct irq_work_queue;              /* work entry */
+	struct kthread_worker irq_worker;		/* kthread worker for PIO/YUV/VBI actions */
+	struct task_struct *irq_worker_task;		/* task for irq_worker */
+	struct kthread_work irq_work;	/* kthread work entry */
 	spinlock_t dma_reg_lock;        /* lock access to DMA engine registers */
 	int cur_dma_stream;		/* index of current stream doing DMA (-1 if none) */
 	int cur_pio_stream;		/* index of current stream doing PIO (-1 if none) */

drivers/media/video/ivtv/ivtv-irq.c

@@ -71,19 +71,10 @@ static void ivtv_pio_work_handler(struct ivtv *itv)
 	write_reg(IVTV_IRQ_ENC_PIO_COMPLETE, 0x44);
 }
 
-void ivtv_irq_work_handler(struct work_struct *work)
+void ivtv_irq_work_handler(struct kthread_work *work)
 {
-	struct ivtv *itv = container_of(work, struct ivtv, irq_work_queue);
+	struct ivtv *itv = container_of(work, struct ivtv, irq_work);
 
-	DEFINE_WAIT(wait);
-
-	if (test_and_clear_bit(IVTV_F_I_WORK_INITED, &itv->i_flags)) {
-		struct sched_param param = { .sched_priority = 99 };
-
-		/* This thread must use the FIFO scheduler as it
-		   is realtime sensitive. */
-		sched_setscheduler(current, SCHED_FIFO, &param);
-	}
 	if (test_and_clear_bit(IVTV_F_I_WORK_HANDLER_PIO, &itv->i_flags))
 		ivtv_pio_work_handler(itv);
 
@@ -975,7 +966,7 @@ irqreturn_t ivtv_irq_handler(int irq, void *dev_id)
 	}
 
 	if (test_and_clear_bit(IVTV_F_I_HAVE_WORK, &itv->i_flags)) {
-		queue_work(itv->irq_work_queues, &itv->irq_work_queue);
+		queue_kthread_work(&itv->irq_worker, &itv->irq_work);
 	}
 
 	spin_unlock(&itv->dma_reg_lock);

drivers/media/video/ivtv/ivtv-irq.h

@@ -46,7 +46,7 @@
 
 irqreturn_t ivtv_irq_handler(int irq, void *dev_id);
 
-void ivtv_irq_work_handler(struct work_struct *work);
+void ivtv_irq_work_handler(struct kthread_work *work);
 void ivtv_dma_stream_dec_prepare(struct ivtv_stream *s, u32 offset, int lock);
 void ivtv_unfinished_dma(unsigned long arg);
 

fs/cachefiles/namei.c

@@ -37,9 +37,9 @@ void __cachefiles_printk_object(struct cachefiles_object *object,
 
 	printk(KERN_ERR "%sobject: OBJ%x\n",
 	       prefix, object->fscache.debug_id);
-	printk(KERN_ERR "%sobjstate=%s fl=%lx swfl=%lx ev=%lx[%lx]\n",
+	printk(KERN_ERR "%sobjstate=%s fl=%lx wbusy=%x ev=%lx[%lx]\n",
 	       prefix, fscache_object_states[object->fscache.state],
-	       object->fscache.flags, object->fscache.work.flags,
+	       object->fscache.flags, work_busy(&object->fscache.work),
 	       object->fscache.events,
 	       object->fscache.event_mask & FSCACHE_OBJECT_EVENTS_MASK);
 	printk(KERN_ERR "%sops=%u inp=%u exc=%u\n",
@@ -212,7 +212,7 @@ wait_for_old_object:
 
 		/* if the object we're waiting for is queued for processing,
 		 * then just put ourselves on the queue behind it */
-		if (slow_work_is_queued(&xobject->fscache.work)) {
+		if (work_pending(&xobject->fscache.work)) {
 			_debug("queue OBJ%x behind OBJ%x immediately",
 			       object->fscache.debug_id,
 			       xobject->fscache.debug_id);
@@ -220,8 +220,7 @@ wait_for_old_object:
 		}
 
 		/* otherwise we sleep until either the object we're waiting for
-		 * is done, or the slow-work facility wants the thread back to
-		 * do other work */
+		 * is done, or the fscache_object is congested */
 		wq = bit_waitqueue(&xobject->flags, CACHEFILES_OBJECT_ACTIVE);
 		init_wait(&wait);
 		requeue = false;
@@ -229,8 +228,8 @@ wait_for_old_object:
 			prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
 			if (!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags))
 				break;
-			requeue = slow_work_sleep_till_thread_needed(
-				&object->fscache.work, &timeout);
+
+			requeue = fscache_object_sleep_till_congested(&timeout);
 		} while (timeout > 0 && !requeue);
 		finish_wait(wq, &wait);
 

fs/cachefiles/rdwr.c

@@ -422,7 +422,7 @@ int cachefiles_read_or_alloc_page(struct fscache_retrieval *op,
 	shift = PAGE_SHIFT - inode->i_sb->s_blocksize_bits;
 
 	op->op.flags &= FSCACHE_OP_KEEP_FLAGS;
-	op->op.flags |= FSCACHE_OP_FAST;
+	op->op.flags |= FSCACHE_OP_ASYNC;
 	op->op.processor = cachefiles_read_copier;
 
 	pagevec_init(&pagevec, 0);
@@ -729,7 +729,7 @@ int cachefiles_read_or_alloc_pages(struct fscache_retrieval *op,
 	pagevec_init(&pagevec, 0);
 
 	op->op.flags &= FSCACHE_OP_KEEP_FLAGS;
-	op->op.flags |= FSCACHE_OP_FAST;
+	op->op.flags |= FSCACHE_OP_ASYNC;
 	op->op.processor = cachefiles_read_copier;
 
 	INIT_LIST_HEAD(&backpages);

fs/cifs/Kconfig

@@ -2,7 +2,6 @@ config CIFS
 	tristate "CIFS support (advanced network filesystem, SMBFS successor)"
 	depends on INET
 	select NLS
-	select SLOW_WORK
 	help
 	  This is the client VFS module for the Common Internet File System
 	  (CIFS) protocol which is the successor to the Server Message Block

fs/cifs/cifsfs.c

@@ -939,15 +939,10 @@ init_cifs(void)
 	if (rc)
 		goto out_unregister_key_type;
 #endif
-	rc = slow_work_register_user(THIS_MODULE);
-	if (rc)
-		goto out_unregister_resolver_key;
 
 	return 0;
 
- out_unregister_resolver_key:
 #ifdef CONFIG_CIFS_DFS_UPCALL
-	cifs_exit_dns_resolver();
  out_unregister_key_type:
 #endif
 #ifdef CONFIG_CIFS_UPCALL

fs/cifs/cifsglob.h

@@ -22,7 +22,7 @@
 #include <linux/in.h>
 #include <linux/in6.h>
 #include <linux/slab.h>
-#include <linux/slow-work.h>
+#include <linux/workqueue.h>
 #include "cifs_fs_sb.h"
 #include "cifsacl.h"
 /*
@@ -356,7 +356,7 @@ struct cifsFileInfo {
 	atomic_t count;		/* reference count */
 	struct mutex fh_mutex; /* prevents reopen race after dead ses*/
 	struct cifs_search_info srch_inf;
-	struct slow_work oplock_break; /* slow_work job for oplock breaks */
+	struct work_struct oplock_break; /* work for oplock breaks */
 };
 
 /* Take a reference on the file private data */
@@ -728,6 +728,10 @@ GLOBAL_EXTERN unsigned int cifs_min_rcv;    /* min size of big ntwrk buf pool */
 GLOBAL_EXTERN unsigned int cifs_min_small;  /* min size of small buf pool */
 GLOBAL_EXTERN unsigned int cifs_max_pending; /* MAX requests at once to server*/
 
+void cifs_oplock_break(struct work_struct *work);
+void cifs_oplock_break_get(struct cifsFileInfo *cfile);
+void cifs_oplock_break_put(struct cifsFileInfo *cfile);
+
 extern const struct slow_work_ops cifs_oplock_break_ops;
 
 #endif	/* _CIFS_GLOB_H */

fs/cifs/dir.c

@@ -157,7 +157,7 @@ cifs_new_fileinfo(struct inode *newinode, __u16 fileHandle,
 	mutex_init(&pCifsFile->lock_mutex);
 	INIT_LIST_HEAD(&pCifsFile->llist);
 	atomic_set(&pCifsFile->count, 1);
-	slow_work_init(&pCifsFile->oplock_break, &cifs_oplock_break_ops);
+	INIT_WORK(&pCifsFile->oplock_break, cifs_oplock_break);
 
 	write_lock(&GlobalSMBSeslock);
 	list_add(&pCifsFile->tlist, &cifs_sb->tcon->openFileList);

fs/cifs/file.c

@@ -2307,8 +2307,7 @@ static void cifs_invalidate_page(struct page *page, unsigned long offset)
 		cifs_fscache_invalidate_page(page, &cifsi->vfs_inode);
 }
 
-static void
-cifs_oplock_break(struct slow_work *work)
+void cifs_oplock_break(struct work_struct *work)
 {
 	struct cifsFileInfo *cfile = container_of(work, struct cifsFileInfo,
 						  oplock_break);
@@ -2345,33 +2344,30 @@ cifs_oplock_break(struct slow_work *work)
 				 LOCKING_ANDX_OPLOCK_RELEASE, false);
 		cFYI(1, "Oplock release rc = %d", rc);
 	}
+
+	/*
+	 * We might have kicked in before is_valid_oplock_break()
+	 * finished grabbing reference for us.  Make sure it's done by
+	 * waiting for GlobalSMSSeslock.
+	 */
+	write_lock(&GlobalSMBSeslock);
+	write_unlock(&GlobalSMBSeslock);
+
+	cifs_oplock_break_put(cfile);
 }
 
-static int
-cifs_oplock_break_get(struct slow_work *work)
+void cifs_oplock_break_get(struct cifsFileInfo *cfile)
 {
-	struct cifsFileInfo *cfile = container_of(work, struct cifsFileInfo,
-						  oplock_break);
 	mntget(cfile->mnt);
 	cifsFileInfo_get(cfile);
-	return 0;
 }
 
-static void
-cifs_oplock_break_put(struct slow_work *work)
+void cifs_oplock_break_put(struct cifsFileInfo *cfile)
 {
-	struct cifsFileInfo *cfile = container_of(work, struct cifsFileInfo,
-						  oplock_break);
 	mntput(cfile->mnt);
 	cifsFileInfo_put(cfile);
 }
 
-const struct slow_work_ops cifs_oplock_break_ops = {
-	.get_ref	= cifs_oplock_break_get,
-	.put_ref	= cifs_oplock_break_put,
-	.execute	= cifs_oplock_break,
-};
-
 const struct address_space_operations cifs_addr_ops = {
 	.readpage = cifs_readpage,
 	.readpages = cifs_readpages,

fs/cifs/misc.c

@@ -498,7 +498,6 @@ is_valid_oplock_break(struct smb_hdr *buf, struct TCP_Server_Info *srv)
 	struct cifsTconInfo *tcon;
 	struct cifsInodeInfo *pCifsInode;
 	struct cifsFileInfo *netfile;
-	int rc;
 
 	cFYI(1, "Checking for oplock break or dnotify response");
 	if ((pSMB->hdr.Command == SMB_COM_NT_TRANSACT) &&
@@ -583,13 +582,18 @@ is_valid_oplock_break(struct smb_hdr *buf, struct TCP_Server_Info *srv)
 				pCifsInode->clientCanCacheAll = false;
 				if (pSMB->OplockLevel == 0)
 					pCifsInode->clientCanCacheRead = false;
-				rc = slow_work_enqueue(&netfile->oplock_break);
-				if (rc) {
-					cERROR(1, "failed to enqueue oplock "
-						   "break: %d\n", rc);
-				} else {
-					netfile->oplock_break_cancelled = false;
-				}
+
+				/*
+				 * cifs_oplock_break_put() can't be called
+				 * from here.  Get reference after queueing
+				 * succeeded.  cifs_oplock_break() will
+				 * synchronize using GlobalSMSSeslock.
+				 */
+				if (queue_work(system_nrt_wq,
+					       &netfile->oplock_break))
+					cifs_oplock_break_get(netfile);
+				netfile->oplock_break_cancelled = false;
+
 				read_unlock(&GlobalSMBSeslock);
 				read_unlock(&cifs_tcp_ses_lock);
 				return true;

fs/fscache/Kconfig

@@ -1,7 +1,6 @@
 
 config FSCACHE
 	tristate "General filesystem local caching manager"
-	select SLOW_WORK
 	help
 	  This option enables a generic filesystem caching manager that can be
 	  used by various network and other filesystems to cache data locally.

fs/fscache/internal.h

@@ -82,6 +82,14 @@ extern unsigned fscache_defer_lookup;
 extern unsigned fscache_defer_create;
 extern unsigned fscache_debug;
 extern struct kobject *fscache_root;
+extern struct workqueue_struct *fscache_object_wq;
+extern struct workqueue_struct *fscache_op_wq;
+DECLARE_PER_CPU(wait_queue_head_t, fscache_object_cong_wait);
+
+static inline bool fscache_object_congested(void)
+{
+	return workqueue_congested(WORK_CPU_UNBOUND, fscache_object_wq);
+}
 
 extern int fscache_wait_bit(void *);
 extern int fscache_wait_bit_interruptible(void *);

fs/fscache/main.c

@@ -15,6 +15,7 @@
 #include <linux/sched.h>
 #include <linux/completion.h>
 #include <linux/slab.h>
+#include <linux/seq_file.h>
 #include "internal.h"
 
 MODULE_DESCRIPTION("FS Cache Manager");
@@ -40,22 +41,105 @@ MODULE_PARM_DESC(fscache_debug,
 		 "FS-Cache debugging mask");
 
 struct kobject *fscache_root;
+struct workqueue_struct *fscache_object_wq;
+struct workqueue_struct *fscache_op_wq;
+
+DEFINE_PER_CPU(wait_queue_head_t, fscache_object_cong_wait);
+
+/* these values serve as lower bounds, will be adjusted in fscache_init() */
+static unsigned fscache_object_max_active = 4;
+static unsigned fscache_op_max_active = 2;
+
+#ifdef CONFIG_SYSCTL
+static struct ctl_table_header *fscache_sysctl_header;
+
+static int fscache_max_active_sysctl(struct ctl_table *table, int write,
+				     void __user *buffer,
+				     size_t *lenp, loff_t *ppos)
+{
+	struct workqueue_struct **wqp = table->extra1;
+	unsigned int *datap = table->data;
+	int ret;
+
+	ret = proc_dointvec(table, write, buffer, lenp, ppos);
+	if (ret == 0)
+		workqueue_set_max_active(*wqp, *datap);
+	return ret;
+}
+
+ctl_table fscache_sysctls[] = {
+	{
+		.procname	= "object_max_active",
+		.data		= &fscache_object_max_active,
+		.maxlen		= sizeof(unsigned),
+		.mode		= 0644,
+		.proc_handler	= fscache_max_active_sysctl,
+		.extra1		= &fscache_object_wq,
+	},
+	{
+		.procname	= "operation_max_active",
+		.data		= &fscache_op_max_active,
+		.maxlen		= sizeof(unsigned),
+		.mode		= 0644,
+		.proc_handler	= fscache_max_active_sysctl,
+		.extra1		= &fscache_op_wq,
+	},
+	{}
+};
+
+ctl_table fscache_sysctls_root[] = {
+	{
+		.procname	= "fscache",
+		.mode		= 0555,
+		.child		= fscache_sysctls,
+	},
+	{}
+};
+#endif
 
 /*
  * initialise the fs caching module
  */
 static int __init fscache_init(void)
 {
+	unsigned int nr_cpus = num_possible_cpus();
+	unsigned int cpu;
 	int ret;
 
-	ret = slow_work_register_user(THIS_MODULE);
-	if (ret < 0)
-		goto error_slow_work;
+	fscache_object_max_active =
+		clamp_val(nr_cpus,
+			  fscache_object_max_active, WQ_UNBOUND_MAX_ACTIVE);
+
+	ret = -ENOMEM;
+	fscache_object_wq = alloc_workqueue("fscache_object", WQ_UNBOUND,
+					    fscache_object_max_active);
+	if (!fscache_object_wq)
+		goto error_object_wq;
+
+	fscache_op_max_active =
+		clamp_val(fscache_object_max_active / 2,
+			  fscache_op_max_active, WQ_UNBOUND_MAX_ACTIVE);
+
+	ret = -ENOMEM;
+	fscache_op_wq = alloc_workqueue("fscache_operation", WQ_UNBOUND,
+					fscache_op_max_active);
+	if (!fscache_op_wq)
+		goto error_op_wq;
+
+	for_each_possible_cpu(cpu)
+		init_waitqueue_head(&per_cpu(fscache_object_cong_wait, cpu));
 
 	ret = fscache_proc_init();
 	if (ret < 0)
 		goto error_proc;
 
+#ifdef CONFIG_SYSCTL
+	ret = -ENOMEM;
+	fscache_sysctl_header = register_sysctl_table(fscache_sysctls_root);
+	if (!fscache_sysctl_header)
+		goto error_sysctl;
+#endif
+
 	fscache_cookie_jar = kmem_cache_create("fscache_cookie_jar",
 					       sizeof(struct fscache_cookie),
 					       0,
@@ -78,10 +162,16 @@ static int __init fscache_init(void)
 error_kobj:
 	kmem_cache_destroy(fscache_cookie_jar);
 error_cookie_jar:
+#ifdef CONFIG_SYSCTL
+	unregister_sysctl_table(fscache_sysctl_header);
+error_sysctl:
+#endif
 	fscache_proc_cleanup();
 error_proc:
-	slow_work_unregister_user(THIS_MODULE);
-error_slow_work:
+	destroy_workqueue(fscache_op_wq);
+error_op_wq:
+	destroy_workqueue(fscache_object_wq);
+error_object_wq:
 	return ret;
 }
 
@@ -96,8 +186,12 @@ static void __exit fscache_exit(void)
 
 	kobject_put(fscache_root);
 	kmem_cache_destroy(fscache_cookie_jar);
+#ifdef CONFIG_SYSCTL
+	unregister_sysctl_table(fscache_sysctl_header);
+#endif
 	fscache_proc_cleanup();
-	slow_work_unregister_user(THIS_MODULE);
+	destroy_workqueue(fscache_op_wq);
+	destroy_workqueue(fscache_object_wq);
 	printk(KERN_NOTICE "FS-Cache: Unloaded\n");
 }
 

fs/fscache/object-list.c

@@ -34,8 +34,8 @@ struct fscache_objlist_data {
 #define FSCACHE_OBJLIST_CONFIG_NOREADS	0x00000200	/* show objects without active reads */
 #define FSCACHE_OBJLIST_CONFIG_EVENTS	0x00000400	/* show objects with events */
 #define FSCACHE_OBJLIST_CONFIG_NOEVENTS	0x00000800	/* show objects without no events */
-#define FSCACHE_OBJLIST_CONFIG_WORK	0x00001000	/* show objects with slow work */
-#define FSCACHE_OBJLIST_CONFIG_NOWORK	0x00002000	/* show objects without slow work */
+#define FSCACHE_OBJLIST_CONFIG_WORK	0x00001000	/* show objects with work */
+#define FSCACHE_OBJLIST_CONFIG_NOWORK	0x00002000	/* show objects without work */
 
 	u8		buf[512];	/* key and aux data buffer */
 };
@@ -231,12 +231,11 @@ static int fscache_objlist_show(struct seq_file *m, void *v)
 		       READS, NOREADS);
 		FILTER(obj->events & obj->event_mask,
 		       EVENTS, NOEVENTS);
-		FILTER(obj->work.flags & ~(1UL << SLOW_WORK_VERY_SLOW),
-		       WORK, NOWORK);
+		FILTER(work_busy(&obj->work), WORK, NOWORK);
 	}
 
 	seq_printf(m,
-		   "%8x %8x %s %5u %3u %3u %3u %2u %5u %2lx %2lx %1lx %1lx | ",
+		   "%8x %8x %s %5u %3u %3u %3u %2u %5u %2lx %2lx %1lx %1x | ",
 		   obj->debug_id,
 		   obj->parent ? obj->parent->debug_id : -1,
 		   fscache_object_states_short[obj->state],
@@ -249,7 +248,7 @@ static int fscache_objlist_show(struct seq_file *m, void *v)
 		   obj->event_mask & FSCACHE_OBJECT_EVENTS_MASK,
 		   obj->events,
 		   obj->flags,
-		   obj->work.flags);
+		   work_busy(&obj->work));
 
 	no_cookie = true;
 	keylen = auxlen = 0;

fs/fscache/object.c

@@ -14,7 +14,6 @@
 
 #define FSCACHE_DEBUG_LEVEL COOKIE
 #include <linux/module.h>
-#include <linux/seq_file.h>
 #include "internal.h"
 
 const char *fscache_object_states[FSCACHE_OBJECT__NSTATES] = {
@@ -50,12 +49,8 @@ const char fscache_object_states_short[FSCACHE_OBJECT__NSTATES][5] = {
 	[FSCACHE_OBJECT_DEAD]		= "DEAD",
 };
 
-static void fscache_object_slow_work_put_ref(struct slow_work *);
-static int  fscache_object_slow_work_get_ref(struct slow_work *);
-static void fscache_object_slow_work_execute(struct slow_work *);
-#ifdef CONFIG_SLOW_WORK_DEBUG
-static void fscache_object_slow_work_desc(struct slow_work *, struct seq_file *);
-#endif
+static int  fscache_get_object(struct fscache_object *);
+static void fscache_put_object(struct fscache_object *);
 static void fscache_initialise_object(struct fscache_object *);
 static void fscache_lookup_object(struct fscache_object *);
 static void fscache_object_available(struct fscache_object *);
@@ -64,17 +59,6 @@ static void fscache_withdraw_object(struct fscache_object *);
 static void fscache_enqueue_dependents(struct fscache_object *);
 static void fscache_dequeue_object(struct fscache_object *);
 
-const struct slow_work_ops fscache_object_slow_work_ops = {
-	.owner		= THIS_MODULE,
-	.get_ref	= fscache_object_slow_work_get_ref,
-	.put_ref	= fscache_object_slow_work_put_ref,
-	.execute	= fscache_object_slow_work_execute,
-#ifdef CONFIG_SLOW_WORK_DEBUG
-	.desc		= fscache_object_slow_work_desc,
-#endif
-};
-EXPORT_SYMBOL(fscache_object_slow_work_ops);
-
 /*
  * we need to notify the parent when an op completes that we had outstanding
  * upon it
@@ -345,7 +329,7 @@ unsupported_event:
 /*
  * execute an object
  */
-static void fscache_object_slow_work_execute(struct slow_work *work)
+void fscache_object_work_func(struct work_struct *work)
 {
 	struct fscache_object *object =
 		container_of(work, struct fscache_object, work);
@@ -359,23 +343,9 @@ static void fscache_object_slow_work_execute(struct slow_work *work)
 	if (object->events & object->event_mask)
 		fscache_enqueue_object(object);
 	clear_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events);
+	fscache_put_object(object);
 }
-
-/*
- * describe an object for slow-work debugging
- */
-#ifdef CONFIG_SLOW_WORK_DEBUG
-static void fscache_object_slow_work_desc(struct slow_work *work,
-					  struct seq_file *m)
-{
-	struct fscache_object *object =
-		container_of(work, struct fscache_object, work);
-
-	seq_printf(m, "FSC: OBJ%x: %s",
-		   object->debug_id,
-		   fscache_object_states_short[object->state]);
-}
-#endif
+EXPORT_SYMBOL(fscache_object_work_func);
 
 /*
  * initialise an object
@@ -393,7 +363,6 @@ static void fscache_initialise_object(struct fscache_object *object)
 	_enter("");
 	ASSERT(object->cookie != NULL);
 	ASSERT(object->cookie->parent != NULL);
-	ASSERT(list_empty(&object->work.link));
 
 	if (object->events & ((1 << FSCACHE_OBJECT_EV_ERROR) |
 			      (1 << FSCACHE_OBJECT_EV_RELEASE) |
@@ -671,10 +640,8 @@ static void fscache_drop_object(struct fscache_object *object)
 		object->parent = NULL;
 	}
 
-	/* this just shifts the object release to the slow work processor */
-	fscache_stat(&fscache_n_cop_put_object);
-	object->cache->ops->put_object(object);
-	fscache_stat_d(&fscache_n_cop_put_object);
+	/* this just shifts the object release to the work processor */
+	fscache_put_object(object);
 
 	_leave("");
 }
@@ -758,12 +725,10 @@ void fscache_withdrawing_object(struct fscache_cache *cache,
 }
 
 /*
- * allow the slow work item processor to get a ref on an object
+ * get a ref on an object
  */
-static int fscache_object_slow_work_get_ref(struct slow_work *work)
+static int fscache_get_object(struct fscache_object *object)
 {
-	struct fscache_object *object =
-		container_of(work, struct fscache_object, work);
 	int ret;
 
 	fscache_stat(&fscache_n_cop_grab_object);
@@ -773,13 +738,10 @@ static int fscache_object_slow_work_get_ref(struct slow_work *work)
 }
 
 /*
- * allow the slow work item processor to discard a ref on a work item
+ * discard a ref on a work item
  */
-static void fscache_object_slow_work_put_ref(struct slow_work *work)
+static void fscache_put_object(struct fscache_object *object)
 {
-	struct fscache_object *object =
-		container_of(work, struct fscache_object, work);
-
 	fscache_stat(&fscache_n_cop_put_object);
 	object->cache->ops->put_object(object);
 	fscache_stat_d(&fscache_n_cop_put_object);
@@ -792,8 +754,48 @@ void fscache_enqueue_object(struct fscache_object *object)
 {
 	_enter("{OBJ%x}", object->debug_id);
 
-	slow_work_enqueue(&object->work);
+	if (fscache_get_object(object) >= 0) {
+		wait_queue_head_t *cong_wq =
+			&get_cpu_var(fscache_object_cong_wait);
+
+		if (queue_work(fscache_object_wq, &object->work)) {
+			if (fscache_object_congested())
+				wake_up(cong_wq);
+		} else
+			fscache_put_object(object);
+
+		put_cpu_var(fscache_object_cong_wait);
+	}
+}
+
+/**
+ * fscache_object_sleep_till_congested - Sleep until object wq is congested
+ * @timoutp: Scheduler sleep timeout
+ *
+ * Allow an object handler to sleep until the object workqueue is congested.
+ *
+ * The caller must set up a wake up event before calling this and must have set
+ * the appropriate sleep mode (such as TASK_UNINTERRUPTIBLE) and tested its own
+ * condition before calling this function as no test is made here.
+ *
+ * %true is returned if the object wq is congested, %false otherwise.
+ */
+bool fscache_object_sleep_till_congested(signed long *timeoutp)
+{
+	wait_queue_head_t *cong_wq = &__get_cpu_var(fscache_object_cong_wait);
+	DEFINE_WAIT(wait);
+
+	if (fscache_object_congested())
+		return true;
+
+	add_wait_queue_exclusive(cong_wq, &wait);
+	if (!fscache_object_congested())
+		*timeoutp = schedule_timeout(*timeoutp);
+	finish_wait(cong_wq, &wait);
+
+	return fscache_object_congested();
 }
+EXPORT_SYMBOL_GPL(fscache_object_sleep_till_congested);
 
 /*
  * enqueue the dependents of an object for metadata-type processing
@@ -819,9 +821,7 @@ static void fscache_enqueue_dependents(struct fscache_object *object)
 
 		/* sort onto appropriate lists */
 		fscache_enqueue_object(dep);
-		fscache_stat(&fscache_n_cop_put_object);
-		dep->cache->ops->put_object(dep);
-		fscache_stat_d(&fscache_n_cop_put_object);
+		fscache_put_object(dep);
 
 		if (!list_empty(&object->dependents))
 			cond_resched_lock(&object->lock);

fs/fscache/operation.c

@@ -42,16 +42,12 @@ void fscache_enqueue_operation(struct fscache_operation *op)
 
 	fscache_stat(&fscache_n_op_enqueue);
 	switch (op->flags & FSCACHE_OP_TYPE) {
-	case FSCACHE_OP_FAST:
-		_debug("queue fast");
+	case FSCACHE_OP_ASYNC:
+		_debug("queue async");
 		atomic_inc(&op->usage);
-		if (!schedule_work(&op->fast_work))
+		if (!queue_work(fscache_op_wq, &op->work))
 			fscache_put_operation(op);
 		break;
-	case FSCACHE_OP_SLOW:
-		_debug("queue slow");
-		slow_work_enqueue(&op->slow_work);
-		break;
 	case FSCACHE_OP_MYTHREAD:
 		_debug("queue for caller's attention");
 		break;
@@ -455,36 +451,13 @@ void fscache_operation_gc(struct work_struct *work)
 }
 
 /*
- * allow the slow work item processor to get a ref on an operation
- */
-static int fscache_op_get_ref(struct slow_work *work)
-{
-	struct fscache_operation *op =
-		container_of(work, struct fscache_operation, slow_work);
-
-	atomic_inc(&op->usage);
-	return 0;
-}
-
-/*
- * allow the slow work item processor to discard a ref on an operation
- */
-static void fscache_op_put_ref(struct slow_work *work)
-{
-	struct fscache_operation *op =
-		container_of(work, struct fscache_operation, slow_work);
-
-	fscache_put_operation(op);
-}
-
-/*
- * execute an operation using the slow thread pool to provide processing context
- * - the caller holds a ref to this object, so we don't need to hold one
+ * execute an operation using fs_op_wq to provide processing context -
+ * the caller holds a ref to this object, so we don't need to hold one
  */
-static void fscache_op_execute(struct slow_work *work)
+void fscache_op_work_func(struct work_struct *work)
 {
 	struct fscache_operation *op =
-		container_of(work, struct fscache_operation, slow_work);
+		container_of(work, struct fscache_operation, work);
 	unsigned long start;
 
 	_enter("{OBJ%x OP%x,%d}",
@@ -494,31 +467,7 @@ static void fscache_op_execute(struct slow_work *work)
 	start = jiffies;
 	op->processor(op);
 	fscache_hist(fscache_ops_histogram, start);
+	fscache_put_operation(op);
 
 	_leave("");
 }
-
-/*
- * describe an operation for slow-work debugging
- */
-#ifdef CONFIG_SLOW_WORK_DEBUG
-static void fscache_op_desc(struct slow_work *work, struct seq_file *m)
-{
-	struct fscache_operation *op =
-		container_of(work, struct fscache_operation, slow_work);
-
-	seq_printf(m, "FSC: OBJ%x OP%x: %s/%s fl=%lx",
-		   op->object->debug_id, op->debug_id,
-		   op->name, op->state, op->flags);
-}
-#endif
-
-const struct slow_work_ops fscache_op_slow_work_ops = {
-	.owner		= THIS_MODULE,
-	.get_ref	= fscache_op_get_ref,
-	.put_ref	= fscache_op_put_ref,
-	.execute	= fscache_op_execute,
-#ifdef CONFIG_SLOW_WORK_DEBUG
-	.desc		= fscache_op_desc,
-#endif
-};

fs/fscache/page.c

@@ -105,7 +105,7 @@ bool __fscache_maybe_release_page(struct fscache_cookie *cookie,
 
 page_busy:
 	/* we might want to wait here, but that could deadlock the allocator as
-	 * the slow-work threads writing to the cache may all end up sleeping
+	 * the work threads writing to the cache may all end up sleeping
 	 * on memory allocation */
 	fscache_stat(&fscache_n_store_vmscan_busy);
 	return false;
@@ -188,9 +188,8 @@ int __fscache_attr_changed(struct fscache_cookie *cookie)
 		return -ENOMEM;
 	}
 
-	fscache_operation_init(op, NULL);
-	fscache_operation_init_slow(op, fscache_attr_changed_op);
-	op->flags = FSCACHE_OP_SLOW | (1 << FSCACHE_OP_EXCLUSIVE);
+	fscache_operation_init(op, fscache_attr_changed_op, NULL);
+	op->flags = FSCACHE_OP_ASYNC | (1 << FSCACHE_OP_EXCLUSIVE);
 	fscache_set_op_name(op, "Attr");
 
 	spin_lock(&cookie->lock);
@@ -217,24 +216,6 @@ nobufs:
 }
 EXPORT_SYMBOL(__fscache_attr_changed);
 
-/*
- * handle secondary execution given to a retrieval op on behalf of the
- * cache
- */
-static void fscache_retrieval_work(struct work_struct *work)
-{
-	struct fscache_retrieval *op =
-		container_of(work, struct fscache_retrieval, op.fast_work);
-	unsigned long start;
-
-	_enter("{OP%x}", op->op.debug_id);
-
-	start = jiffies;
-	op->op.processor(&op->op);
-	fscache_hist(fscache_ops_histogram, start);
-	fscache_put_operation(&op->op);
-}
-
 /*
  * release a retrieval op reference
  */
@@ -269,13 +250,12 @@ static struct fscache_retrieval *fscache_alloc_retrieval(
 		return NULL;
 	}
 
-	fscache_operation_init(&op->op, fscache_release_retrieval_op);
+	fscache_operation_init(&op->op, NULL, fscache_release_retrieval_op);
 	op->op.flags	= FSCACHE_OP_MYTHREAD | (1 << FSCACHE_OP_WAITING);
 	op->mapping	= mapping;
 	op->end_io_func	= end_io_func;
 	op->context	= context;
 	op->start_time	= jiffies;
-	INIT_WORK(&op->op.fast_work, fscache_retrieval_work);
 	INIT_LIST_HEAD(&op->to_do);
 	fscache_set_op_name(&op->op, "Retr");
 	return op;
@@ -795,9 +775,9 @@ int __fscache_write_page(struct fscache_cookie *cookie,
 	if (!op)
 		goto nomem;
 
-	fscache_operation_init(&op->op, fscache_release_write_op);
-	fscache_operation_init_slow(&op->op, fscache_write_op);
-	op->op.flags = FSCACHE_OP_SLOW | (1 << FSCACHE_OP_WAITING);
+	fscache_operation_init(&op->op, fscache_write_op,
+			       fscache_release_write_op);
+	op->op.flags = FSCACHE_OP_ASYNC | (1 << FSCACHE_OP_WAITING);
 	fscache_set_op_name(&op->op, "Write1");
 
 	ret = radix_tree_preload(gfp & ~__GFP_HIGHMEM);
@@ -852,7 +832,7 @@ int __fscache_write_page(struct fscache_cookie *cookie,
 	fscache_stat(&fscache_n_store_ops);
 	fscache_stat(&fscache_n_stores_ok);
 
-	/* the slow work queue now carries its own ref on the object */
+	/* the work queue now carries its own ref on the object */
 	fscache_put_operation(&op->op);
 	_leave(" = 0");
 	return 0;

fs/gfs2/Kconfig

@@ -7,7 +7,6 @@ config GFS2_FS
 	select IP_SCTP if DLM_SCTP
 	select FS_POSIX_ACL
 	select CRC32
-	select SLOW_WORK
 	select QUOTACTL
 	help
 	  A cluster filesystem.

fs/gfs2/incore.h

@@ -12,7 +12,6 @@
 
 #include <linux/fs.h>
 #include <linux/workqueue.h>
-#include <linux/slow-work.h>
 #include <linux/dlm.h>
 #include <linux/buffer_head.h>
 
@@ -383,7 +382,7 @@ struct gfs2_journal_extent {
 struct gfs2_jdesc {
 	struct list_head jd_list;
 	struct list_head extent_list;
-	struct slow_work jd_work;
+	struct work_struct jd_work;
 	struct inode *jd_inode;
 	unsigned long jd_flags;
 #define JDF_RECOVERY 1

fs/gfs2/main.c

@@ -15,7 +15,6 @@
 #include <linux/init.h>
 #include <linux/gfs2_ondisk.h>
 #include <asm/atomic.h>
-#include <linux/slow-work.h>
 
 #include "gfs2.h"
 #include "incore.h"
@@ -24,6 +23,7 @@
 #include "util.h"
 #include "glock.h"
 #include "quota.h"
+#include "recovery.h"
 
 static struct shrinker qd_shrinker = {
 	.shrink = gfs2_shrink_qd_memory,
@@ -138,9 +138,11 @@ static int __init init_gfs2_fs(void)
 	if (error)
 		goto fail_unregister;
 
-	error = slow_work_register_user(THIS_MODULE);
-	if (error)
-		goto fail_slow;
+	error = -ENOMEM;
+	gfs_recovery_wq = alloc_workqueue("gfs_recovery",
+					  WQ_NON_REENTRANT | WQ_RESCUER, 0);
+	if (!gfs_recovery_wq)
+		goto fail_wq;
 
 	gfs2_register_debugfs();
 
@@ -148,7 +150,7 @@ static int __init init_gfs2_fs(void)
 
 	return 0;
 
-fail_slow:
+fail_wq:
 	unregister_filesystem(&gfs2meta_fs_type);
 fail_unregister:
 	unregister_filesystem(&gfs2_fs_type);
@@ -190,7 +192,7 @@ static void __exit exit_gfs2_fs(void)
 	gfs2_unregister_debugfs();
 	unregister_filesystem(&gfs2_fs_type);
 	unregister_filesystem(&gfs2meta_fs_type);
-	slow_work_unregister_user(THIS_MODULE);
+	destroy_workqueue(gfs_recovery_wq);
 
 	kmem_cache_destroy(gfs2_quotad_cachep);
 	kmem_cache_destroy(gfs2_rgrpd_cachep);

fs/gfs2/ops_fstype.c

@@ -17,7 +17,6 @@
 #include <linux/namei.h>
 #include <linux/mount.h>
 #include <linux/gfs2_ondisk.h>
-#include <linux/slow-work.h>
 #include <linux/quotaops.h>
 
 #include "gfs2.h"
@@ -673,7 +672,7 @@ static int gfs2_jindex_hold(struct gfs2_sbd *sdp, struct gfs2_holder *ji_gh)
 			break;
 
 		INIT_LIST_HEAD(&jd->extent_list);
-		slow_work_init(&jd->jd_work, &gfs2_recover_ops);
+		INIT_WORK(&jd->jd_work, gfs2_recover_func);
 		jd->jd_inode = gfs2_lookupi(sdp->sd_jindex, &name, 1);
 		if (!jd->jd_inode || IS_ERR(jd->jd_inode)) {
 			if (!jd->jd_inode)
@@ -782,7 +781,8 @@ static int init_journal(struct gfs2_sbd *sdp, int undo)
 	if (sdp->sd_lockstruct.ls_first) {
 		unsigned int x;
 		for (x = 0; x < sdp->sd_journals; x++) {
-			error = gfs2_recover_journal(gfs2_jdesc_find(sdp, x));
+			error = gfs2_recover_journal(gfs2_jdesc_find(sdp, x),
+						     true);
 			if (error) {
 				fs_err(sdp, "error recovering journal %u: %d\n",
 				       x, error);
@@ -792,7 +792,7 @@ static int init_journal(struct gfs2_sbd *sdp, int undo)
 
 		gfs2_others_may_mount(sdp);
 	} else if (!sdp->sd_args.ar_spectator) {
-		error = gfs2_recover_journal(sdp->sd_jdesc);
+		error = gfs2_recover_journal(sdp->sd_jdesc, true);
 		if (error) {
 			fs_err(sdp, "error recovering my journal: %d\n", error);
 			goto fail_jinode_gh;

fs/gfs2/recovery.c

@@ -14,7 +14,6 @@
 #include <linux/buffer_head.h>
 #include <linux/gfs2_ondisk.h>
 #include <linux/crc32.h>
-#include <linux/slow-work.h>
 
 #include "gfs2.h"
 #include "incore.h"
@@ -28,6 +27,8 @@
 #include "util.h"
 #include "dir.h"
 
+struct workqueue_struct *gfs_recovery_wq;
+
 int gfs2_replay_read_block(struct gfs2_jdesc *jd, unsigned int blk,
 			   struct buffer_head **bh)
 {
@@ -443,23 +444,7 @@ static void gfs2_recovery_done(struct gfs2_sbd *sdp, unsigned int jid,
         kobject_uevent_env(&sdp->sd_kobj, KOBJ_CHANGE, envp);
 }
 
-static int gfs2_recover_get_ref(struct slow_work *work)
-{
-	struct gfs2_jdesc *jd = container_of(work, struct gfs2_jdesc, jd_work);
-	if (test_and_set_bit(JDF_RECOVERY, &jd->jd_flags))
-		return -EBUSY;
-	return 0;
-}
-
-static void gfs2_recover_put_ref(struct slow_work *work)
-{
-	struct gfs2_jdesc *jd = container_of(work, struct gfs2_jdesc, jd_work);
-	clear_bit(JDF_RECOVERY, &jd->jd_flags);
-	smp_mb__after_clear_bit();
-	wake_up_bit(&jd->jd_flags, JDF_RECOVERY);
-}
-
-static void gfs2_recover_work(struct slow_work *work)
+void gfs2_recover_func(struct work_struct *work)
 {
 	struct gfs2_jdesc *jd = container_of(work, struct gfs2_jdesc, jd_work);
 	struct gfs2_inode *ip = GFS2_I(jd->jd_inode);
@@ -578,7 +563,7 @@ static void gfs2_recover_work(struct slow_work *work)
 		gfs2_glock_dq_uninit(&j_gh);
 
 	fs_info(sdp, "jid=%u: Done\n", jd->jd_jid);
-	return;
+	goto done;
 
 fail_gunlock_tr:
 	gfs2_glock_dq_uninit(&t_gh);
@@ -590,32 +575,35 @@ fail_gunlock_j:
 	}
 
 	fs_info(sdp, "jid=%u: %s\n", jd->jd_jid, (error) ? "Failed" : "Done");
-
 fail:
 	gfs2_recovery_done(sdp, jd->jd_jid, LM_RD_GAVEUP);
+done:
+	clear_bit(JDF_RECOVERY, &jd->jd_flags);
+	smp_mb__after_clear_bit();
+	wake_up_bit(&jd->jd_flags, JDF_RECOVERY);
 }
 
-struct slow_work_ops gfs2_recover_ops = {
-	.owner	 = THIS_MODULE,
-	.get_ref = gfs2_recover_get_ref,
-	.put_ref = gfs2_recover_put_ref,
-	.execute = gfs2_recover_work,
-};
-
-
 static int gfs2_recovery_wait(void *word)
 {
 	schedule();
 	return 0;
 }
 
-int gfs2_recover_journal(struct gfs2_jdesc *jd)
+int gfs2_recover_journal(struct gfs2_jdesc *jd, bool wait)
 {
 	int rv;
-	rv = slow_work_enqueue(&jd->jd_work);
-	if (rv)
-		return rv;
-	wait_on_bit(&jd->jd_flags, JDF_RECOVERY, gfs2_recovery_wait, TASK_UNINTERRUPTIBLE);
+
+	if (test_and_set_bit(JDF_RECOVERY, &jd->jd_flags))
+		return -EBUSY;
+
+	/* we have JDF_RECOVERY, queue should always succeed */
+	rv = queue_work(gfs_recovery_wq, &jd->jd_work);
+	BUG_ON(!rv);
+
+	if (wait)
+		wait_on_bit(&jd->jd_flags, JDF_RECOVERY, gfs2_recovery_wait,
+			    TASK_UNINTERRUPTIBLE);
+
 	return 0;
 }
 

fs/gfs2/recovery.h

@@ -12,6 +12,8 @@
 
 #include "incore.h"
 
+extern struct workqueue_struct *gfs_recovery_wq;
+
 static inline void gfs2_replay_incr_blk(struct gfs2_sbd *sdp, unsigned int *blk)
 {
 	if (++*blk == sdp->sd_jdesc->jd_blocks)
@@ -27,8 +29,8 @@ extern void gfs2_revoke_clean(struct gfs2_sbd *sdp);
 
 extern int gfs2_find_jhead(struct gfs2_jdesc *jd,
 		    struct gfs2_log_header_host *head);
-extern int gfs2_recover_journal(struct gfs2_jdesc *gfs2_jd);
-extern struct slow_work_ops gfs2_recover_ops;
+extern int gfs2_recover_journal(struct gfs2_jdesc *gfs2_jd, bool wait);
+extern void gfs2_recover_func(struct work_struct *work);
 
 #endif /* __RECOVERY_DOT_H__ */
 

fs/gfs2/sys.c

@@ -25,6 +25,7 @@
 #include "quota.h"
 #include "util.h"
 #include "glops.h"
+#include "recovery.h"
 
 struct gfs2_attr {
 	struct attribute attr;
@@ -376,7 +377,7 @@ static ssize_t recover_store(struct gfs2_sbd *sdp, const char *buf, size_t len)
 	list_for_each_entry(jd, &sdp->sd_jindex_list, jd_list) {
 		if (jd->jd_jid != jid)
 			continue;
-		rv = slow_work_enqueue(&jd->jd_work);
+		rv = gfs2_recover_journal(jd, false);
 		break;
 	}
 out:

include/drm/drm_crtc.h

@@ -31,7 +31,6 @@
 #include <linux/idr.h>
 
 #include <linux/fb.h>
-#include <linux/slow-work.h>
 
 struct drm_device;
 struct drm_mode_set;
@@ -595,7 +594,7 @@ struct drm_mode_config {
 
 	/* output poll support */
 	bool poll_enabled;
-	struct delayed_slow_work output_poll_slow_work;
+	struct delayed_work output_poll_work;
 
 	/* pointers to standard properties */
 	struct list_head property_blob_list;

include/linux/cpu.h

@@ -71,6 +71,8 @@ enum {
 	/* migration should happen before other stuff but after perf */
 	CPU_PRI_PERF		= 20,
 	CPU_PRI_MIGRATION	= 10,
+	/* prepare workqueues for other notifiers */
+	CPU_PRI_WORKQUEUE	= 5,
 };
 
 #ifdef CONFIG_SMP

include/linux/fscache-cache.h

@@ -20,7 +20,7 @@
 
 #include <linux/fscache.h>
 #include <linux/sched.h>
-#include <linux/slow-work.h>
+#include <linux/workqueue.h>
 
 #define NR_MAXCACHES BITS_PER_LONG
 
@@ -76,18 +76,14 @@ typedef void (*fscache_operation_release_t)(struct fscache_operation *op);
 typedef void (*fscache_operation_processor_t)(struct fscache_operation *op);
 
 struct fscache_operation {
-	union {
-		struct work_struct fast_work;	/* record for fast ops */
-		struct slow_work slow_work;	/* record for (very) slow ops */
-	};
+	struct work_struct	work;		/* record for async ops */
 	struct list_head	pend_link;	/* link in object->pending_ops */
 	struct fscache_object	*object;	/* object to be operated upon */
 
 	unsigned long		flags;
 #define FSCACHE_OP_TYPE		0x000f	/* operation type */
-#define FSCACHE_OP_FAST		0x0001	/* - fast op, processor may not sleep for disk */
-#define FSCACHE_OP_SLOW		0x0002	/* - (very) slow op, processor may sleep for disk */
-#define FSCACHE_OP_MYTHREAD	0x0003	/* - processing is done be issuing thread, not pool */
+#define FSCACHE_OP_ASYNC	0x0001	/* - async op, processor may sleep for disk */
+#define FSCACHE_OP_MYTHREAD	0x0002	/* - processing is done be issuing thread, not pool */
 #define FSCACHE_OP_WAITING	4	/* cleared when op is woken */
 #define FSCACHE_OP_EXCLUSIVE	5	/* exclusive op, other ops must wait */
 #define FSCACHE_OP_DEAD		6	/* op is now dead */
@@ -105,7 +101,8 @@ struct fscache_operation {
 	/* operation releaser */
 	fscache_operation_release_t release;
 
-#ifdef CONFIG_SLOW_WORK_DEBUG
+#ifdef CONFIG_WORKQUEUE_DEBUGFS
+	struct work_struct put_work;	/* work to delay operation put */
 	const char *name;		/* operation name */
 	const char *state;		/* operation state */
 #define fscache_set_op_name(OP, N)	do { (OP)->name  = (N); } while(0)
@@ -117,7 +114,7 @@ struct fscache_operation {
 };
 
 extern atomic_t fscache_op_debug_id;
-extern const struct slow_work_ops fscache_op_slow_work_ops;
+extern void fscache_op_work_func(struct work_struct *work);
 
 extern void fscache_enqueue_operation(struct fscache_operation *);
 extern void fscache_put_operation(struct fscache_operation *);
@@ -128,33 +125,21 @@ extern void fscache_put_operation(struct fscache_operation *);
  * @release: The release function to assign
  *
  * Do basic initialisation of an operation.  The caller must still set flags,
- * object, either fast_work or slow_work if necessary, and processor if needed.
+ * object and processor if needed.
  */
 static inline void fscache_operation_init(struct fscache_operation *op,
-					  fscache_operation_release_t release)
+					fscache_operation_processor_t processor,
+					fscache_operation_release_t release)
 {
+	INIT_WORK(&op->work, fscache_op_work_func);
 	atomic_set(&op->usage, 1);
 	op->debug_id = atomic_inc_return(&fscache_op_debug_id);
+	op->processor = processor;
 	op->release = release;
 	INIT_LIST_HEAD(&op->pend_link);
 	fscache_set_op_state(op, "Init");
 }
 
-/**
- * fscache_operation_init_slow - Do additional initialisation of a slow op
- * @op: The operation to initialise
- * @processor: The processor function to assign
- *
- * Do additional initialisation of an operation as required for slow work.
- */
-static inline
-void fscache_operation_init_slow(struct fscache_operation *op,
-				 fscache_operation_processor_t processor)
-{
-	op->processor = processor;
-	slow_work_init(&op->slow_work, &fscache_op_slow_work_ops);
-}
-
 /*
  * data read operation
  */
@@ -389,7 +374,7 @@ struct fscache_object {
 	struct fscache_cache	*cache;		/* cache that supplied this object */
 	struct fscache_cookie	*cookie;	/* netfs's file/index object */
 	struct fscache_object	*parent;	/* parent object */
-	struct slow_work	work;		/* attention scheduling record */
+	struct work_struct	work;		/* attention scheduling record */
 	struct list_head	dependents;	/* FIFO of dependent objects */
 	struct list_head	dep_link;	/* link in parent's dependents list */
 	struct list_head	pending_ops;	/* unstarted operations on this object */
@@ -411,7 +396,7 @@ extern const char *fscache_object_states[];
 	(test_bit(FSCACHE_IOERROR, &(obj)->cache->flags) &&	\
 	 (obj)->state >= FSCACHE_OBJECT_DYING)
 
-extern const struct slow_work_ops fscache_object_slow_work_ops;
+extern void fscache_object_work_func(struct work_struct *work);
 
 /**
  * fscache_object_init - Initialise a cache object description
@@ -433,7 +418,7 @@ void fscache_object_init(struct fscache_object *object,
 	spin_lock_init(&object->lock);
 	INIT_LIST_HEAD(&object->cache_link);
 	INIT_HLIST_NODE(&object->cookie_link);
-	vslow_work_init(&object->work, &fscache_object_slow_work_ops);
+	INIT_WORK(&object->work, fscache_object_work_func);
 	INIT_LIST_HEAD(&object->dependents);
 	INIT_LIST_HEAD(&object->dep_link);
 	INIT_LIST_HEAD(&object->pending_ops);
@@ -534,6 +519,8 @@ extern void fscache_io_error(struct fscache_cache *cache);
 extern void fscache_mark_pages_cached(struct fscache_retrieval *op,
 				      struct pagevec *pagevec);
 
+extern bool fscache_object_sleep_till_congested(signed long *timeoutp);
+
 extern enum fscache_checkaux fscache_check_aux(struct fscache_object *object,
 					       const void *data,
 					       uint16_t datalen);

include/linux/kthread.h

@@ -30,8 +30,73 @@ struct task_struct *kthread_create(int (*threadfn)(void *data),
 void kthread_bind(struct task_struct *k, unsigned int cpu);
 int kthread_stop(struct task_struct *k);
 int kthread_should_stop(void);
+void *kthread_data(struct task_struct *k);
 
 int kthreadd(void *unused);
 extern struct task_struct *kthreadd_task;
 
+/*
+ * Simple work processor based on kthread.
+ *
+ * This provides easier way to make use of kthreads.  A kthread_work
+ * can be queued and flushed using queue/flush_kthread_work()
+ * respectively.  Queued kthread_works are processed by a kthread
+ * running kthread_worker_fn().
+ *
+ * A kthread_work can't be freed while it is executing.
+ */
+struct kthread_work;
+typedef void (*kthread_work_func_t)(struct kthread_work *work);
+
+struct kthread_worker {
+	spinlock_t		lock;
+	struct list_head	work_list;
+	struct task_struct	*task;
+};
+
+struct kthread_work {
+	struct list_head	node;
+	kthread_work_func_t	func;
+	wait_queue_head_t	done;
+	atomic_t		flushing;
+	int			queue_seq;
+	int			done_seq;
+};
+
+#define KTHREAD_WORKER_INIT(worker)	{				\
+	.lock = SPIN_LOCK_UNLOCKED,					\
+	.work_list = LIST_HEAD_INIT((worker).work_list),		\
+	}
+
+#define KTHREAD_WORK_INIT(work, fn)	{				\
+	.node = LIST_HEAD_INIT((work).node),				\
+	.func = (fn),							\
+	.done = __WAIT_QUEUE_HEAD_INITIALIZER((work).done),		\
+	.flushing = ATOMIC_INIT(0),					\
+	}
+
+#define DEFINE_KTHREAD_WORKER(worker)					\
+	struct kthread_worker worker = KTHREAD_WORKER_INIT(worker)
+
+#define DEFINE_KTHREAD_WORK(work, fn)					\
+	struct kthread_work work = KTHREAD_WORK_INIT(work, fn)
+
+static inline void init_kthread_worker(struct kthread_worker *worker)
+{
+	*worker = (struct kthread_worker)KTHREAD_WORKER_INIT(*worker);
+}
+
+static inline void init_kthread_work(struct kthread_work *work,
+				     kthread_work_func_t fn)
+{
+	*work = (struct kthread_work)KTHREAD_WORK_INIT(*work, fn);
+}
+
+int kthread_worker_fn(void *worker_ptr);
+
+bool queue_kthread_work(struct kthread_worker *worker,
+			struct kthread_work *work);
+void flush_kthread_work(struct kthread_work *work);
+void flush_kthread_worker(struct kthread_worker *worker);
+
 #endif /* _LINUX_KTHREAD_H */

include/linux/libata.h

@@ -751,6 +751,7 @@ struct ata_port {
 	struct ata_host		*host;
 	struct device 		*dev;
 
+	struct mutex		scsi_scan_mutex;
 	struct delayed_work	hotplug_task;
 	struct work_struct	scsi_rescan_task;
 

include/linux/slow-work.h

@@ -1,163 +0,0 @@
-/* Worker thread pool for slow items, such as filesystem lookups or mkdirs
- *
- * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
- * Written by David Howells (dhowells@redhat.com)
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public Licence
- * as published by the Free Software Foundation; either version
- * 2 of the Licence, or (at your option) any later version.
- *
- * See Documentation/slow-work.txt
- */
-
-#ifndef _LINUX_SLOW_WORK_H
-#define _LINUX_SLOW_WORK_H
-
-#ifdef CONFIG_SLOW_WORK
-
-#include <linux/sysctl.h>
-#include <linux/timer.h>
-
-struct slow_work;
-#ifdef CONFIG_SLOW_WORK_DEBUG
-struct seq_file;
-#endif
-
-/*
- * The operations used to support slow work items
- */
-struct slow_work_ops {
-	/* owner */
-	struct module *owner;
-
-	/* get a ref on a work item
-	 * - return 0 if successful, -ve if not
-	 */
-	int (*get_ref)(struct slow_work *work);
-
-	/* discard a ref to a work item */
-	void (*put_ref)(struct slow_work *work);
-
-	/* execute a work item */
-	void (*execute)(struct slow_work *work);
-
-#ifdef CONFIG_SLOW_WORK_DEBUG
-	/* describe a work item for debugfs */
-	void (*desc)(struct slow_work *work, struct seq_file *m);
-#endif
-};
-
-/*
- * A slow work item
- * - A reference is held on the parent object by the thread pool when it is
- *   queued
- */
-struct slow_work {
-	struct module		*owner;	/* the owning module */
-	unsigned long		flags;
-#define SLOW_WORK_PENDING	0	/* item pending (further) execution */
-#define SLOW_WORK_EXECUTING	1	/* item currently executing */
-#define SLOW_WORK_ENQ_DEFERRED	2	/* item enqueue deferred */
-#define SLOW_WORK_VERY_SLOW	3	/* item is very slow */
-#define SLOW_WORK_CANCELLING	4	/* item is being cancelled, don't enqueue */
-#define SLOW_WORK_DELAYED	5	/* item is struct delayed_slow_work with active timer */
-	const struct slow_work_ops *ops; /* operations table for this item */
-	struct list_head	link;	/* link in queue */
-#ifdef CONFIG_SLOW_WORK_DEBUG
-	struct timespec		mark;	/* jiffies at which queued or exec begun */
-#endif
-};
-
-struct delayed_slow_work {
-	struct slow_work	work;
-	struct timer_list	timer;
-};
-
-/**
- * slow_work_init - Initialise a slow work item
- * @work: The work item to initialise
- * @ops: The operations to use to handle the slow work item
- *
- * Initialise a slow work item.
- */
-static inline void slow_work_init(struct slow_work *work,
-				  const struct slow_work_ops *ops)
-{
-	work->flags = 0;
-	work->ops = ops;
-	INIT_LIST_HEAD(&work->link);
-}
-
-/**
- * slow_work_init - Initialise a delayed slow work item
- * @work: The work item to initialise
- * @ops: The operations to use to handle the slow work item
- *
- * Initialise a delayed slow work item.
- */
-static inline void delayed_slow_work_init(struct delayed_slow_work *dwork,
-					  const struct slow_work_ops *ops)
-{
-	init_timer(&dwork->timer);
-	slow_work_init(&dwork->work, ops);
-}
-
-/**
- * vslow_work_init - Initialise a very slow work item
- * @work: The work item to initialise
- * @ops: The operations to use to handle the slow work item
- *
- * Initialise a very slow work item.  This item will be restricted such that
- * only a certain number of the pool threads will be able to execute items of
- * this type.
- */
-static inline void vslow_work_init(struct slow_work *work,
-				   const struct slow_work_ops *ops)
-{
-	work->flags = 1 << SLOW_WORK_VERY_SLOW;
-	work->ops = ops;
-	INIT_LIST_HEAD(&work->link);
-}
-
-/**
- * slow_work_is_queued - Determine if a slow work item is on the work queue
- * work: The work item to test
- *
- * Determine if the specified slow-work item is on the work queue.  This
- * returns true if it is actually on the queue.
- *
- * If the item is executing and has been marked for requeue when execution
- * finishes, then false will be returned.
- *
- * Anyone wishing to wait for completion of execution can wait on the
- * SLOW_WORK_EXECUTING bit.
- */
-static inline bool slow_work_is_queued(struct slow_work *work)
-{
-	unsigned long flags = work->flags;
-	return flags & SLOW_WORK_PENDING && !(flags & SLOW_WORK_EXECUTING);
-}
-
-extern int slow_work_enqueue(struct slow_work *work);
-extern void slow_work_cancel(struct slow_work *work);
-extern int slow_work_register_user(struct module *owner);
-extern void slow_work_unregister_user(struct module *owner);
-
-extern int delayed_slow_work_enqueue(struct delayed_slow_work *dwork,
-				     unsigned long delay);
-
-static inline void delayed_slow_work_cancel(struct delayed_slow_work *dwork)
-{
-	slow_work_cancel(&dwork->work);
-}
-
-extern bool slow_work_sleep_till_thread_needed(struct slow_work *work,
-					       signed long *_timeout);
-
-#ifdef CONFIG_SYSCTL
-extern ctl_table slow_work_sysctls[];
-#endif
-
-#endif /* CONFIG_SLOW_WORK */
-#endif /* _LINUX_SLOW_WORK_H */

include/linux/workqueue.h

@@ -9,6 +9,7 @@
 #include <linux/linkage.h>
 #include <linux/bitops.h>
 #include <linux/lockdep.h>
+#include <linux/threads.h>
 #include <asm/atomic.h>
 
 struct workqueue_struct;
@@ -22,12 +23,59 @@ typedef void (*work_func_t)(struct work_struct *work);
  */
 #define work_data_bits(work) ((unsigned long *)(&(work)->data))
 
+enum {
+	WORK_STRUCT_PENDING_BIT	= 0,	/* work item is pending execution */
+	WORK_STRUCT_CWQ_BIT	= 1,	/* data points to cwq */
+	WORK_STRUCT_LINKED_BIT	= 2,	/* next work is linked to this one */
+#ifdef CONFIG_DEBUG_OBJECTS_WORK
+	WORK_STRUCT_STATIC_BIT	= 3,	/* static initializer (debugobjects) */
+	WORK_STRUCT_COLOR_SHIFT	= 4,	/* color for workqueue flushing */
+#else
+	WORK_STRUCT_COLOR_SHIFT	= 3,	/* color for workqueue flushing */
+#endif
+
+	WORK_STRUCT_COLOR_BITS	= 4,
+
+	WORK_STRUCT_PENDING	= 1 << WORK_STRUCT_PENDING_BIT,
+	WORK_STRUCT_CWQ		= 1 << WORK_STRUCT_CWQ_BIT,
+	WORK_STRUCT_LINKED	= 1 << WORK_STRUCT_LINKED_BIT,
+#ifdef CONFIG_DEBUG_OBJECTS_WORK
+	WORK_STRUCT_STATIC	= 1 << WORK_STRUCT_STATIC_BIT,
+#else
+	WORK_STRUCT_STATIC	= 0,
+#endif
+
+	/*
+	 * The last color is no color used for works which don't
+	 * participate in workqueue flushing.
+	 */
+	WORK_NR_COLORS		= (1 << WORK_STRUCT_COLOR_BITS) - 1,
+	WORK_NO_COLOR		= WORK_NR_COLORS,
+
+	/* special cpu IDs */
+	WORK_CPU_UNBOUND	= NR_CPUS,
+	WORK_CPU_NONE		= NR_CPUS + 1,
+	WORK_CPU_LAST		= WORK_CPU_NONE,
+
+	/*
+	 * Reserve 7 bits off of cwq pointer w/ debugobjects turned
+	 * off.  This makes cwqs aligned to 128 bytes which isn't too
+	 * excessive while allowing 15 workqueue flush colors.
+	 */
+	WORK_STRUCT_FLAG_BITS	= WORK_STRUCT_COLOR_SHIFT +
+				  WORK_STRUCT_COLOR_BITS,
+
+	WORK_STRUCT_FLAG_MASK	= (1UL << WORK_STRUCT_FLAG_BITS) - 1,
+	WORK_STRUCT_WQ_DATA_MASK = ~WORK_STRUCT_FLAG_MASK,
+	WORK_STRUCT_NO_CPU	= WORK_CPU_NONE << WORK_STRUCT_FLAG_BITS,
+
+	/* bit mask for work_busy() return values */
+	WORK_BUSY_PENDING	= 1 << 0,
+	WORK_BUSY_RUNNING	= 1 << 1,
+};
+
 struct work_struct {
 	atomic_long_t data;
-#define WORK_STRUCT_PENDING 0		/* T if work item pending execution */
-#define WORK_STRUCT_STATIC  1		/* static initializer (debugobjects) */
-#define WORK_STRUCT_FLAG_MASK (3UL)
-#define WORK_STRUCT_WQ_DATA_MASK (~WORK_STRUCT_FLAG_MASK)
 	struct list_head entry;
 	work_func_t func;
 #ifdef CONFIG_LOCKDEP
@@ -35,8 +83,9 @@ struct work_struct {
 #endif
 };
 
-#define WORK_DATA_INIT()	ATOMIC_LONG_INIT(0)
-#define WORK_DATA_STATIC_INIT()	ATOMIC_LONG_INIT(2)
+#define WORK_DATA_INIT()	ATOMIC_LONG_INIT(WORK_STRUCT_NO_CPU)
+#define WORK_DATA_STATIC_INIT()	\
+	ATOMIC_LONG_INIT(WORK_STRUCT_NO_CPU | WORK_STRUCT_STATIC)
 
 struct delayed_work {
 	struct work_struct work;
@@ -96,9 +145,14 @@ struct execute_work {
 #ifdef CONFIG_DEBUG_OBJECTS_WORK
 extern void __init_work(struct work_struct *work, int onstack);
 extern void destroy_work_on_stack(struct work_struct *work);
+static inline unsigned int work_static(struct work_struct *work)
+{
+	return *work_data_bits(work) & WORK_STRUCT_STATIC;
+}
 #else
 static inline void __init_work(struct work_struct *work, int onstack) { }
 static inline void destroy_work_on_stack(struct work_struct *work) { }
+static inline unsigned int work_static(struct work_struct *work) { return 0; }
 #endif
 
 /*
@@ -162,7 +216,7 @@ static inline void destroy_work_on_stack(struct work_struct *work) { }
  * @work: The work item in question
  */
 #define work_pending(work) \
-	test_bit(WORK_STRUCT_PENDING, work_data_bits(work))
+	test_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))
 
 /**
  * delayed_work_pending - Find out whether a delayable work item is currently
@@ -177,16 +231,56 @@ static inline void destroy_work_on_stack(struct work_struct *work) { }
  * @work: The work item in question
  */
 #define work_clear_pending(work) \
-	clear_bit(WORK_STRUCT_PENDING, work_data_bits(work))
+	clear_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))
+
+enum {
+	WQ_NON_REENTRANT	= 1 << 0, /* guarantee non-reentrance */
+	WQ_UNBOUND		= 1 << 1, /* not bound to any cpu */
+	WQ_FREEZEABLE		= 1 << 2, /* freeze during suspend */
+	WQ_RESCUER		= 1 << 3, /* has an rescue worker */
+	WQ_HIGHPRI		= 1 << 4, /* high priority */
+	WQ_CPU_INTENSIVE	= 1 << 5, /* cpu instensive workqueue */
+
+	WQ_MAX_ACTIVE		= 512,	  /* I like 512, better ideas? */
+	WQ_MAX_UNBOUND_PER_CPU	= 4,	  /* 4 * #cpus for unbound wq */
+	WQ_DFL_ACTIVE		= WQ_MAX_ACTIVE / 2,
+};
+
+/* unbound wq's aren't per-cpu, scale max_active according to #cpus */
+#define WQ_UNBOUND_MAX_ACTIVE	\
+	max_t(int, WQ_MAX_ACTIVE, num_possible_cpus() * WQ_MAX_UNBOUND_PER_CPU)
 
+/*
+ * System-wide workqueues which are always present.
+ *
+ * system_wq is the one used by schedule[_delayed]_work[_on]().
+ * Multi-CPU multi-threaded.  There are users which expect relatively
+ * short queue flush time.  Don't queue works which can run for too
+ * long.
+ *
+ * system_long_wq is similar to system_wq but may host long running
+ * works.  Queue flushing might take relatively long.
+ *
+ * system_nrt_wq is non-reentrant and guarantees that any given work
+ * item is never executed in parallel by multiple CPUs.  Queue
+ * flushing might take relatively long.
+ *
+ * system_unbound_wq is unbound workqueue.  Workers are not bound to
+ * any specific CPU, not concurrency managed, and all queued works are
+ * executed immediately as long as max_active limit is not reached and
+ * resources are available.
+ */
+extern struct workqueue_struct *system_wq;
+extern struct workqueue_struct *system_long_wq;
+extern struct workqueue_struct *system_nrt_wq;
+extern struct workqueue_struct *system_unbound_wq;
 
 extern struct workqueue_struct *
-__create_workqueue_key(const char *name, int singlethread,
-		       int freezeable, int rt, struct lock_class_key *key,
-		       const char *lock_name);
+__alloc_workqueue_key(const char *name, unsigned int flags, int max_active,
+		      struct lock_class_key *key, const char *lock_name);
 
 #ifdef CONFIG_LOCKDEP
-#define __create_workqueue(name, singlethread, freezeable, rt)	\
+#define alloc_workqueue(name, flags, max_active)		\
 ({								\
 	static struct lock_class_key __key;			\
 	const char *__lock_name;				\
@@ -196,20 +290,20 @@ __create_workqueue_key(const char *name, int singlethread,
 	else							\
 		__lock_name = #name;				\
 								\
-	__create_workqueue_key((name), (singlethread),		\
-			       (freezeable), (rt), &__key,	\
-			       __lock_name);			\
+	__alloc_workqueue_key((name), (flags), (max_active),	\
+			      &__key, __lock_name);		\
 })
 #else
-#define __create_workqueue(name, singlethread, freezeable, rt)	\
-	__create_workqueue_key((name), (singlethread), (freezeable), (rt), \
-			       NULL, NULL)
+#define alloc_workqueue(name, flags, max_active)		\
+	__alloc_workqueue_key((name), (flags), (max_active), NULL, NULL)
 #endif
 
-#define create_workqueue(name) __create_workqueue((name), 0, 0, 0)
-#define create_rt_workqueue(name) __create_workqueue((name), 0, 0, 1)
-#define create_freezeable_workqueue(name) __create_workqueue((name), 1, 1, 0)
-#define create_singlethread_workqueue(name) __create_workqueue((name), 1, 0, 0)
+#define create_workqueue(name)					\
+	alloc_workqueue((name), WQ_RESCUER, 1)
+#define create_freezeable_workqueue(name)			\
+	alloc_workqueue((name), WQ_FREEZEABLE | WQ_UNBOUND | WQ_RESCUER, 1)
+#define create_singlethread_workqueue(name)			\
+	alloc_workqueue((name), WQ_UNBOUND | WQ_RESCUER, 1)
 
 extern void destroy_workqueue(struct workqueue_struct *wq);
 
@@ -231,16 +325,19 @@ extern int schedule_delayed_work(struct delayed_work *work, unsigned long delay)
 extern int schedule_delayed_work_on(int cpu, struct delayed_work *work,
 					unsigned long delay);
 extern int schedule_on_each_cpu(work_func_t func);
-extern int current_is_keventd(void);
 extern int keventd_up(void);
 
-extern void init_workqueues(void);
 int execute_in_process_context(work_func_t fn, struct execute_work *);
 
 extern int flush_work(struct work_struct *work);
-
 extern int cancel_work_sync(struct work_struct *work);
 
+extern void workqueue_set_max_active(struct workqueue_struct *wq,
+				     int max_active);
+extern bool workqueue_congested(unsigned int cpu, struct workqueue_struct *wq);
+extern unsigned int work_cpu(struct work_struct *work);
+extern unsigned int work_busy(struct work_struct *work);
+
 /*
  * Kill off a pending schedule_delayed_work().  Note that the work callback
  * function may still be running on return from cancel_delayed_work(), unless
@@ -298,7 +395,14 @@ static inline long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg)
 long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg);
 #endif /* CONFIG_SMP */
 
+#ifdef CONFIG_FREEZER
+extern void freeze_workqueues_begin(void);
+extern bool freeze_workqueues_busy(void);
+extern void thaw_workqueues(void);
+#endif /* CONFIG_FREEZER */
+
 #ifdef CONFIG_LOCKDEP
 int in_workqueue_context(struct workqueue_struct *wq);
 #endif
+
 #endif

include/trace/events/workqueue.h

@@ -1,92 +0,0 @@
-#undef TRACE_SYSTEM
-#define TRACE_SYSTEM workqueue
-
-#if !defined(_TRACE_WORKQUEUE_H) || defined(TRACE_HEADER_MULTI_READ)
-#define _TRACE_WORKQUEUE_H
-
-#include <linux/workqueue.h>
-#include <linux/sched.h>
-#include <linux/tracepoint.h>
-
-DECLARE_EVENT_CLASS(workqueue,
-
-	TP_PROTO(struct task_struct *wq_thread, struct work_struct *work),
-
-	TP_ARGS(wq_thread, work),
-
-	TP_STRUCT__entry(
-		__array(char,		thread_comm,	TASK_COMM_LEN)
-		__field(pid_t,		thread_pid)
-		__field(work_func_t,	func)
-	),
-
-	TP_fast_assign(
-		memcpy(__entry->thread_comm, wq_thread->comm, TASK_COMM_LEN);
-		__entry->thread_pid	= wq_thread->pid;
-		__entry->func		= work->func;
-	),
-
-	TP_printk("thread=%s:%d func=%pf", __entry->thread_comm,
-		__entry->thread_pid, __entry->func)
-);
-
-DEFINE_EVENT(workqueue, workqueue_insertion,
-
-	TP_PROTO(struct task_struct *wq_thread, struct work_struct *work),
-
-	TP_ARGS(wq_thread, work)
-);
-
-DEFINE_EVENT(workqueue, workqueue_execution,
-
-	TP_PROTO(struct task_struct *wq_thread, struct work_struct *work),
-
-	TP_ARGS(wq_thread, work)
-);
-
-/* Trace the creation of one workqueue thread on a cpu */
-TRACE_EVENT(workqueue_creation,
-
-	TP_PROTO(struct task_struct *wq_thread, int cpu),
-
-	TP_ARGS(wq_thread, cpu),
-
-	TP_STRUCT__entry(
-		__array(char,	thread_comm,	TASK_COMM_LEN)
-		__field(pid_t,	thread_pid)
-		__field(int,	cpu)
-	),
-
-	TP_fast_assign(
-		memcpy(__entry->thread_comm, wq_thread->comm, TASK_COMM_LEN);
-		__entry->thread_pid	= wq_thread->pid;
-		__entry->cpu		= cpu;
-	),
-
-	TP_printk("thread=%s:%d cpu=%d", __entry->thread_comm,
-		__entry->thread_pid, __entry->cpu)
-);
-
-TRACE_EVENT(workqueue_destruction,
-
-	TP_PROTO(struct task_struct *wq_thread),
-
-	TP_ARGS(wq_thread),
-
-	TP_STRUCT__entry(
-		__array(char,	thread_comm,	TASK_COMM_LEN)
-		__field(pid_t,	thread_pid)
-	),
-
-	TP_fast_assign(
-		memcpy(__entry->thread_comm, wq_thread->comm, TASK_COMM_LEN);
-		__entry->thread_pid	= wq_thread->pid;
-	),
-
-	TP_printk("thread=%s:%d", __entry->thread_comm, __entry->thread_pid)
-);
-
-#endif /* _TRACE_WORKQUEUE_H */
-
-/* This part must be outside protection */
-#include <trace/define_trace.h>

init/Kconfig

@@ -1143,30 +1143,6 @@ config TRACEPOINTS
 
 source "arch/Kconfig"
 
-config SLOW_WORK
-	default n
-	bool
-	help
-	  The slow work thread pool provides a number of dynamically allocated
-	  threads that can be used by the kernel to perform operations that
-	  take a relatively long time.
-
-	  An example of this would be CacheFiles doing a path lookup followed
-	  by a series of mkdirs and a create call, all of which have to touch
-	  disk.
-
-	  See Documentation/slow-work.txt.
-
-config SLOW_WORK_DEBUG
-	bool "Slow work debugging through debugfs"
-	default n
-	depends on SLOW_WORK && DEBUG_FS
-	help
-	  Display the contents of the slow work run queue through debugfs,
-	  including items currently executing.
-
-	  See Documentation/slow-work.txt.
-
 endmenu		# General setup
 
 config HAVE_GENERIC_DMA_COHERENT

init/main.c

@@ -32,7 +32,6 @@
 #include <linux/start_kernel.h>
 #include <linux/security.h>
 #include <linux/smp.h>
-#include <linux/workqueue.h>
 #include <linux/profile.h>
 #include <linux/rcupdate.h>
 #include <linux/moduleparam.h>
@@ -789,7 +788,6 @@ static void __init do_initcalls(void)
  */
 static void __init do_basic_setup(void)
 {
-	init_workqueues();
 	cpuset_init_smp();
 	usermodehelper_init();
 	init_tmpfs();

kernel/Makefile

@@ -99,8 +99,6 @@ obj-$(CONFIG_TRACING) += trace/
 obj-$(CONFIG_X86_DS) += trace/
 obj-$(CONFIG_RING_BUFFER) += trace/
 obj-$(CONFIG_SMP) += sched_cpupri.o
-obj-$(CONFIG_SLOW_WORK) += slow-work.o
-obj-$(CONFIG_SLOW_WORK_DEBUG) += slow-work-debugfs.o
 obj-$(CONFIG_PERF_EVENTS) += perf_event.o
 obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o
 obj-$(CONFIG_USER_RETURN_NOTIFIER) += user-return-notifier.o

kernel/async.c

@@ -49,40 +49,33 @@ asynchronous and synchronous parts of the kernel.
 */
 
 #include <linux/async.h>
-#include <linux/bug.h>
 #include <linux/module.h>
 #include <linux/wait.h>
 #include <linux/sched.h>
-#include <linux/init.h>
-#include <linux/kthread.h>
-#include <linux/delay.h>
 #include <linux/slab.h>
+#include <linux/workqueue.h>
 #include <asm/atomic.h>
 
 static async_cookie_t next_cookie = 1;
 
-#define MAX_THREADS	256
 #define MAX_WORK	32768
 
 static LIST_HEAD(async_pending);
 static LIST_HEAD(async_running);
 static DEFINE_SPINLOCK(async_lock);
 
-static int async_enabled = 0;
-
 struct async_entry {
-	struct list_head list;
-	async_cookie_t   cookie;
-	async_func_ptr	 *func;
-	void             *data;
-	struct list_head *running;
+	struct list_head	list;
+	struct work_struct	work;
+	async_cookie_t		cookie;
+	async_func_ptr		*func;
+	void			*data;
+	struct list_head	*running;
 };
 
 static DECLARE_WAIT_QUEUE_HEAD(async_done);
-static DECLARE_WAIT_QUEUE_HEAD(async_new);
 
 static atomic_t entry_count;
-static atomic_t thread_count;
 
 extern int initcall_debug;
 
@@ -117,27 +110,23 @@ static async_cookie_t  lowest_in_progress(struct list_head *running)
 	spin_unlock_irqrestore(&async_lock, flags);
 	return ret;
 }
+
 /*
  * pick the first pending entry and run it
  */
-static void run_one_entry(void)
+static void async_run_entry_fn(struct work_struct *work)
 {
+	struct async_entry *entry =
+		container_of(work, struct async_entry, work);
 	unsigned long flags;
-	struct async_entry *entry;
 	ktime_t calltime, delta, rettime;
 
-	/* 1) pick one task from the pending queue */
-
+	/* 1) move self to the running queue */
 	spin_lock_irqsave(&async_lock, flags);
-	if (list_empty(&async_pending))
-		goto out;
-	entry = list_first_entry(&async_pending, struct async_entry, list);
-
-	/* 2) move it to the running queue */
 	list_move_tail(&entry->list, entry->running);
 	spin_unlock_irqrestore(&async_lock, flags);
 
-	/* 3) run it (and print duration)*/
+	/* 2) run (and print duration) */
 	if (initcall_debug && system_state == SYSTEM_BOOTING) {
 		printk("calling  %lli_%pF @ %i\n", (long long)entry->cookie,
 			entry->func, task_pid_nr(current));
@@ -153,31 +142,25 @@ static void run_one_entry(void)
 			(long long)ktime_to_ns(delta) >> 10);
 	}
 
-	/* 4) remove it from the running queue */
+	/* 3) remove self from the running queue */
 	spin_lock_irqsave(&async_lock, flags);
 	list_del(&entry->list);
 
-	/* 5) free the entry  */
+	/* 4) free the entry */
 	kfree(entry);
 	atomic_dec(&entry_count);
 
 	spin_unlock_irqrestore(&async_lock, flags);
 
-	/* 6) wake up any waiters. */
+	/* 5) wake up any waiters */
 	wake_up(&async_done);
-	return;
-
-out:
-	spin_unlock_irqrestore(&async_lock, flags);
 }
 
-
 static async_cookie_t __async_schedule(async_func_ptr *ptr, void *data, struct list_head *running)
 {
 	struct async_entry *entry;
 	unsigned long flags;
 	async_cookie_t newcookie;
-	
 
 	/* allow irq-off callers */
 	entry = kzalloc(sizeof(struct async_entry), GFP_ATOMIC);
@@ -186,7 +169,7 @@ static async_cookie_t __async_schedule(async_func_ptr *ptr, void *data, struct l
 	 * If we're out of memory or if there's too much work
 	 * pending already, we execute synchronously.
 	 */
-	if (!async_enabled || !entry || atomic_read(&entry_count) > MAX_WORK) {
+	if (!entry || atomic_read(&entry_count) > MAX_WORK) {
 		kfree(entry);
 		spin_lock_irqsave(&async_lock, flags);
 		newcookie = next_cookie++;
@@ -196,6 +179,7 @@ static async_cookie_t __async_schedule(async_func_ptr *ptr, void *data, struct l
 		ptr(data, newcookie);
 		return newcookie;
 	}
+	INIT_WORK(&entry->work, async_run_entry_fn);
 	entry->func = ptr;
 	entry->data = data;
 	entry->running = running;
@@ -205,7 +189,10 @@ static async_cookie_t __async_schedule(async_func_ptr *ptr, void *data, struct l
 	list_add_tail(&entry->list, &async_pending);
 	atomic_inc(&entry_count);
 	spin_unlock_irqrestore(&async_lock, flags);
-	wake_up(&async_new);
+
+	/* schedule for execution */
+	queue_work(system_unbound_wq, &entry->work);
+
 	return newcookie;
 }
 
@@ -312,87 +299,3 @@ void async_synchronize_cookie(async_cookie_t cookie)
 	async_synchronize_cookie_domain(cookie, &async_running);
 }
 EXPORT_SYMBOL_GPL(async_synchronize_cookie);
-
-
-static int async_thread(void *unused)
-{
-	DECLARE_WAITQUEUE(wq, current);
-	add_wait_queue(&async_new, &wq);
-
-	while (!kthread_should_stop()) {
-		int ret = HZ;
-		set_current_state(TASK_INTERRUPTIBLE);
-		/*
-		 * check the list head without lock.. false positives
-		 * are dealt with inside run_one_entry() while holding
-		 * the lock.
-		 */
-		rmb();
-		if (!list_empty(&async_pending))
-			run_one_entry();
-		else
-			ret = schedule_timeout(HZ);
-
-		if (ret == 0) {
-			/*
-			 * we timed out, this means we as thread are redundant.
-			 * we sign off and die, but we to avoid any races there
-			 * is a last-straw check to see if work snuck in.
-			 */
-			atomic_dec(&thread_count);
-			wmb(); /* manager must see our departure first */
-			if (list_empty(&async_pending))
-				break;
-			/*
-			 * woops work came in between us timing out and us
-			 * signing off; we need to stay alive and keep working.
-			 */
-			atomic_inc(&thread_count);
-		}
-	}
-	remove_wait_queue(&async_new, &wq);
-
-	return 0;
-}
-
-static int async_manager_thread(void *unused)
-{
-	DECLARE_WAITQUEUE(wq, current);
-	add_wait_queue(&async_new, &wq);
-
-	while (!kthread_should_stop()) {
-		int tc, ec;
-
-		set_current_state(TASK_INTERRUPTIBLE);
-
-		tc = atomic_read(&thread_count);
-		rmb();
-		ec = atomic_read(&entry_count);
-
-		while (tc < ec && tc < MAX_THREADS) {
-			if (IS_ERR(kthread_run(async_thread, NULL, "async/%i",
-					       tc))) {
-				msleep(100);
-				continue;
-			}
-			atomic_inc(&thread_count);
-			tc++;
-		}
-
-		schedule();
-	}
-	remove_wait_queue(&async_new, &wq);
-
-	return 0;
-}
-
-static int __init async_init(void)
-{
-	async_enabled =
-		!IS_ERR(kthread_run(async_manager_thread, NULL, "async/mgr"));
-
-	WARN_ON(!async_enabled);
-	return 0;
-}
-
-core_initcall(async_init);

kernel/kthread.c

@@ -14,6 +14,8 @@
 #include <linux/file.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
+#include <linux/slab.h>
+#include <linux/freezer.h>
 #include <trace/events/sched.h>
 
 static DEFINE_SPINLOCK(kthread_create_lock);
@@ -35,6 +37,7 @@ struct kthread_create_info
 
 struct kthread {
 	int should_stop;
+	void *data;
 	struct completion exited;
 };
 
@@ -54,6 +57,19 @@ int kthread_should_stop(void)
 }
 EXPORT_SYMBOL(kthread_should_stop);
 
+/**
+ * kthread_data - return data value specified on kthread creation
+ * @task: kthread task in question
+ *
+ * Return the data value specified when kthread @task was created.
+ * The caller is responsible for ensuring the validity of @task when
+ * calling this function.
+ */
+void *kthread_data(struct task_struct *task)
+{
+	return to_kthread(task)->data;
+}
+
 static int kthread(void *_create)
 {
 	/* Copy data: it's on kthread's stack */
@@ -64,6 +80,7 @@ static int kthread(void *_create)
 	int ret;
 
 	self.should_stop = 0;
+	self.data = data;
 	init_completion(&self.exited);
 	current->vfork_done = &self.exited;
 
@@ -247,3 +264,150 @@ int kthreadd(void *unused)
 
 	return 0;
 }
+
+/**
+ * kthread_worker_fn - kthread function to process kthread_worker
+ * @worker_ptr: pointer to initialized kthread_worker
+ *
+ * This function can be used as @threadfn to kthread_create() or
+ * kthread_run() with @worker_ptr argument pointing to an initialized
+ * kthread_worker.  The started kthread will process work_list until
+ * the it is stopped with kthread_stop().  A kthread can also call
+ * this function directly after extra initialization.
+ *
+ * Different kthreads can be used for the same kthread_worker as long
+ * as there's only one kthread attached to it at any given time.  A
+ * kthread_worker without an attached kthread simply collects queued
+ * kthread_works.
+ */
+int kthread_worker_fn(void *worker_ptr)
+{
+	struct kthread_worker *worker = worker_ptr;
+	struct kthread_work *work;
+
+	WARN_ON(worker->task);
+	worker->task = current;
+repeat:
+	set_current_state(TASK_INTERRUPTIBLE);	/* mb paired w/ kthread_stop */
+
+	if (kthread_should_stop()) {
+		__set_current_state(TASK_RUNNING);
+		spin_lock_irq(&worker->lock);
+		worker->task = NULL;
+		spin_unlock_irq(&worker->lock);
+		return 0;
+	}
+
+	work = NULL;
+	spin_lock_irq(&worker->lock);
+	if (!list_empty(&worker->work_list)) {
+		work = list_first_entry(&worker->work_list,
+					struct kthread_work, node);
+		list_del_init(&work->node);
+	}
+	spin_unlock_irq(&worker->lock);
+
+	if (work) {
+		__set_current_state(TASK_RUNNING);
+		work->func(work);
+		smp_wmb();	/* wmb worker-b0 paired with flush-b1 */
+		work->done_seq = work->queue_seq;
+		smp_mb();	/* mb worker-b1 paired with flush-b0 */
+		if (atomic_read(&work->flushing))
+			wake_up_all(&work->done);
+	} else if (!freezing(current))
+		schedule();
+
+	try_to_freeze();
+	goto repeat;
+}
+EXPORT_SYMBOL_GPL(kthread_worker_fn);
+
+/**
+ * queue_kthread_work - queue a kthread_work
+ * @worker: target kthread_worker
+ * @work: kthread_work to queue
+ *
+ * Queue @work to work processor @task for async execution.  @task
+ * must have been created with kthread_worker_create().  Returns %true
+ * if @work was successfully queued, %false if it was already pending.
+ */
+bool queue_kthread_work(struct kthread_worker *worker,
+			struct kthread_work *work)
+{
+	bool ret = false;
+	unsigned long flags;
+
+	spin_lock_irqsave(&worker->lock, flags);
+	if (list_empty(&work->node)) {
+		list_add_tail(&work->node, &worker->work_list);
+		work->queue_seq++;
+		if (likely(worker->task))
+			wake_up_process(worker->task);
+		ret = true;
+	}
+	spin_unlock_irqrestore(&worker->lock, flags);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(queue_kthread_work);
+
+/**
+ * flush_kthread_work - flush a kthread_work
+ * @work: work to flush
+ *
+ * If @work is queued or executing, wait for it to finish execution.
+ */
+void flush_kthread_work(struct kthread_work *work)
+{
+	int seq = work->queue_seq;
+
+	atomic_inc(&work->flushing);
+
+	/*
+	 * mb flush-b0 paired with worker-b1, to make sure either
+	 * worker sees the above increment or we see done_seq update.
+	 */
+	smp_mb__after_atomic_inc();
+
+	/* A - B <= 0 tests whether B is in front of A regardless of overflow */
+	wait_event(work->done, seq - work->done_seq <= 0);
+	atomic_dec(&work->flushing);
+
+	/*
+	 * rmb flush-b1 paired with worker-b0, to make sure our caller
+	 * sees every change made by work->func().
+	 */
+	smp_mb__after_atomic_dec();
+}
+EXPORT_SYMBOL_GPL(flush_kthread_work);
+
+struct kthread_flush_work {
+	struct kthread_work	work;
+	struct completion	done;
+};
+
+static void kthread_flush_work_fn(struct kthread_work *work)
+{
+	struct kthread_flush_work *fwork =
+		container_of(work, struct kthread_flush_work, work);
+	complete(&fwork->done);
+}
+
+/**
+ * flush_kthread_worker - flush all current works on a kthread_worker
+ * @worker: worker to flush
+ *
+ * Wait until all currently executing or pending works on @worker are
+ * finished.
+ */
+void flush_kthread_worker(struct kthread_worker *worker)
+{
+	struct kthread_flush_work fwork = {
+		KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn),
+		COMPLETION_INITIALIZER_ONSTACK(fwork.done),
+	};
+
+	queue_kthread_work(worker, &fwork.work);
+	wait_for_completion(&fwork.done);
+}
+EXPORT_SYMBOL_GPL(flush_kthread_worker);

kernel/power/process.c

@@ -15,6 +15,7 @@
 #include <linux/syscalls.h>
 #include <linux/freezer.h>
 #include <linux/delay.h>
+#include <linux/workqueue.h>
 
 /* 
  * Timeout for stopping processes
@@ -35,6 +36,7 @@ static int try_to_freeze_tasks(bool sig_only)
 	struct task_struct *g, *p;
 	unsigned long end_time;
 	unsigned int todo;
+	bool wq_busy = false;
 	struct timeval start, end;
 	u64 elapsed_csecs64;
 	unsigned int elapsed_csecs;
@@ -42,6 +44,10 @@ static int try_to_freeze_tasks(bool sig_only)
 	do_gettimeofday(&start);
 
 	end_time = jiffies + TIMEOUT;
+
+	if (!sig_only)
+		freeze_workqueues_begin();
+
 	while (true) {
 		todo = 0;
 		read_lock(&tasklist_lock);
@@ -63,6 +69,12 @@ static int try_to_freeze_tasks(bool sig_only)
 				todo++;
 		} while_each_thread(g, p);
 		read_unlock(&tasklist_lock);
+
+		if (!sig_only) {
+			wq_busy = freeze_workqueues_busy();
+			todo += wq_busy;
+		}
+
 		if (!todo || time_after(jiffies, end_time))
 			break;
 
@@ -86,8 +98,12 @@ static int try_to_freeze_tasks(bool sig_only)
 		 */
 		printk("\n");
 		printk(KERN_ERR "Freezing of tasks failed after %d.%02d seconds "
-				"(%d tasks refusing to freeze):\n",
-				elapsed_csecs / 100, elapsed_csecs % 100, todo);
+		       "(%d tasks refusing to freeze, wq_busy=%d):\n",
+		       elapsed_csecs / 100, elapsed_csecs % 100,
+		       todo - wq_busy, wq_busy);
+
+		thaw_workqueues();
+
 		read_lock(&tasklist_lock);
 		do_each_thread(g, p) {
 			task_lock(p);
@@ -157,6 +173,7 @@ void thaw_processes(void)
 	oom_killer_enable();
 
 	printk("Restarting tasks ... ");
+	thaw_workqueues();
 	thaw_tasks(true);
 	thaw_tasks(false);
 	schedule();

kernel/slow-work-debugfs.c

@@ -1,227 +0,0 @@
-/* Slow work debugging
- *
- * Copyright (C) 2009 Red Hat, Inc. All Rights Reserved.
- * Written by David Howells (dhowells@redhat.com)
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public Licence
- * as published by the Free Software Foundation; either version
- * 2 of the Licence, or (at your option) any later version.
- */
-
-#include <linux/module.h>
-#include <linux/slow-work.h>
-#include <linux/fs.h>
-#include <linux/time.h>
-#include <linux/seq_file.h>
-#include "slow-work.h"
-
-#define ITERATOR_SHIFT		(BITS_PER_LONG - 4)
-#define ITERATOR_SELECTOR	(0xfUL << ITERATOR_SHIFT)
-#define ITERATOR_COUNTER	(~ITERATOR_SELECTOR)
-
-void slow_work_new_thread_desc(struct slow_work *work, struct seq_file *m)
-{
-	seq_puts(m, "Slow-work: New thread");
-}
-
-/*
- * Render the time mark field on a work item into a 5-char time with units plus
- * a space
- */
-static void slow_work_print_mark(struct seq_file *m, struct slow_work *work)
-{
-	struct timespec now, diff;
-
-	now = CURRENT_TIME;
-	diff = timespec_sub(now, work->mark);
-
-	if (diff.tv_sec < 0)
-		seq_puts(m, "  -ve ");
-	else if (diff.tv_sec == 0 && diff.tv_nsec < 1000)
-		seq_printf(m, "%3luns ", diff.tv_nsec);
-	else if (diff.tv_sec == 0 && diff.tv_nsec < 1000000)
-		seq_printf(m, "%3luus ", diff.tv_nsec / 1000);
-	else if (diff.tv_sec == 0 && diff.tv_nsec < 1000000000)
-		seq_printf(m, "%3lums ", diff.tv_nsec / 1000000);
-	else if (diff.tv_sec <= 1)
-		seq_puts(m, "   1s ");
-	else if (diff.tv_sec < 60)
-		seq_printf(m, "%4lus ", diff.tv_sec);
-	else if (diff.tv_sec < 60 * 60)
-		seq_printf(m, "%4lum ", diff.tv_sec / 60);
-	else if (diff.tv_sec < 60 * 60 * 24)
-		seq_printf(m, "%4luh ", diff.tv_sec / 3600);
-	else
-		seq_puts(m, "exces ");
-}
-
-/*
- * Describe a slow work item for debugfs
- */
-static int slow_work_runqueue_show(struct seq_file *m, void *v)
-{
-	struct slow_work *work;
-	struct list_head *p = v;
-	unsigned long id;
-
-	switch ((unsigned long) v) {
-	case 1:
-		seq_puts(m, "THR PID   ITEM ADDR        FL MARK  DESC\n");
-		return 0;
-	case 2:
-		seq_puts(m, "=== ===== ================ == ===== ==========\n");
-		return 0;
-
-	case 3 ... 3 + SLOW_WORK_THREAD_LIMIT - 1:
-		id = (unsigned long) v - 3;
-
-		read_lock(&slow_work_execs_lock);
-		work = slow_work_execs[id];
-		if (work) {
-			smp_read_barrier_depends();
-
-			seq_printf(m, "%3lu %5d %16p %2lx ",
-				   id, slow_work_pids[id], work, work->flags);
-			slow_work_print_mark(m, work);
-
-			if (work->ops->desc)
-				work->ops->desc(work, m);
-			seq_putc(m, '\n');
-		}
-		read_unlock(&slow_work_execs_lock);
-		return 0;
-
-	default:
-		work = list_entry(p, struct slow_work, link);
-		seq_printf(m, "%3s     - %16p %2lx ",
-			   work->flags & SLOW_WORK_VERY_SLOW ? "vsq" : "sq",
-			   work, work->flags);
-		slow_work_print_mark(m, work);
-
-		if (work->ops->desc)
-			work->ops->desc(work, m);
-		seq_putc(m, '\n');
-		return 0;
-	}
-}
-
-/*
- * map the iterator to a work item
- */
-static void *slow_work_runqueue_index(struct seq_file *m, loff_t *_pos)
-{
-	struct list_head *p;
-	unsigned long count, id;
-
-	switch (*_pos >> ITERATOR_SHIFT) {
-	case 0x0:
-		if (*_pos == 0)
-			*_pos = 1;
-		if (*_pos < 3)
-			return (void *)(unsigned long) *_pos;
-		if (*_pos < 3 + SLOW_WORK_THREAD_LIMIT)
-			for (id = *_pos - 3;
-			     id < SLOW_WORK_THREAD_LIMIT;
-			     id++, (*_pos)++)
-				if (slow_work_execs[id])
-					return (void *)(unsigned long) *_pos;
-		*_pos = 0x1UL << ITERATOR_SHIFT;
-
-	case 0x1:
-		count = *_pos & ITERATOR_COUNTER;
-		list_for_each(p, &slow_work_queue) {
-			if (count == 0)
-				return p;
-			count--;
-		}
-		*_pos = 0x2UL << ITERATOR_SHIFT;
-
-	case 0x2:
-		count = *_pos & ITERATOR_COUNTER;
-		list_for_each(p, &vslow_work_queue) {
-			if (count == 0)
-				return p;
-			count--;
-		}
-		*_pos = 0x3UL << ITERATOR_SHIFT;
-
-	default:
-		return NULL;
-	}
-}
-
-/*
- * set up the iterator to start reading from the first line
- */
-static void *slow_work_runqueue_start(struct seq_file *m, loff_t *_pos)
-{
-	spin_lock_irq(&slow_work_queue_lock);
-	return slow_work_runqueue_index(m, _pos);
-}
-
-/*
- * move to the next line
- */
-static void *slow_work_runqueue_next(struct seq_file *m, void *v, loff_t *_pos)
-{
-	struct list_head *p = v;
-	unsigned long selector = *_pos >> ITERATOR_SHIFT;
-
-	(*_pos)++;
-	switch (selector) {
-	case 0x0:
-		return slow_work_runqueue_index(m, _pos);
-
-	case 0x1:
-		if (*_pos >> ITERATOR_SHIFT == 0x1) {
-			p = p->next;
-			if (p != &slow_work_queue)
-				return p;
-		}
-		*_pos = 0x2UL << ITERATOR_SHIFT;
-		p = &vslow_work_queue;
-
-	case 0x2:
-		if (*_pos >> ITERATOR_SHIFT == 0x2) {
-			p = p->next;
-			if (p != &vslow_work_queue)
-				return p;
-		}
-		*_pos = 0x3UL << ITERATOR_SHIFT;
-
-	default:
-		return NULL;
-	}
-}
-
-/*
- * clean up after reading
- */
-static void slow_work_runqueue_stop(struct seq_file *m, void *v)
-{
-	spin_unlock_irq(&slow_work_queue_lock);
-}
-
-static const struct seq_operations slow_work_runqueue_ops = {
-	.start		= slow_work_runqueue_start,
-	.stop		= slow_work_runqueue_stop,
-	.next		= slow_work_runqueue_next,
-	.show		= slow_work_runqueue_show,
-};
-
-/*
- * open "/sys/kernel/debug/slow_work/runqueue" to list queue contents
- */
-static int slow_work_runqueue_open(struct inode *inode, struct file *file)
-{
-	return seq_open(file, &slow_work_runqueue_ops);
-}
-
-const struct file_operations slow_work_runqueue_fops = {
-	.owner		= THIS_MODULE,
-	.open		= slow_work_runqueue_open,
-	.read		= seq_read,
-	.llseek		= seq_lseek,
-	.release	= seq_release,
-};

kernel/slow-work.c

@@ -1,1068 +0,0 @@
-/* Worker thread pool for slow items, such as filesystem lookups or mkdirs
- *
- * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
- * Written by David Howells (dhowells@redhat.com)
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public Licence
- * as published by the Free Software Foundation; either version
- * 2 of the Licence, or (at your option) any later version.
- *
- * See Documentation/slow-work.txt
- */
-
-#include <linux/module.h>
-#include <linux/slow-work.h>
-#include <linux/kthread.h>
-#include <linux/freezer.h>
-#include <linux/wait.h>
-#include <linux/debugfs.h>
-#include "slow-work.h"
-
-static void slow_work_cull_timeout(unsigned long);
-static void slow_work_oom_timeout(unsigned long);
-
-#ifdef CONFIG_SYSCTL
-static int slow_work_min_threads_sysctl(struct ctl_table *, int,
-					void __user *, size_t *, loff_t *);
-
-static int slow_work_max_threads_sysctl(struct ctl_table *, int ,
-					void __user *, size_t *, loff_t *);
-#endif
-
-/*
- * The pool of threads has at least min threads in it as long as someone is
- * using the facility, and may have as many as max.
- *
- * A portion of the pool may be processing very slow operations.
- */
-static unsigned slow_work_min_threads = 2;
-static unsigned slow_work_max_threads = 4;
-static unsigned vslow_work_proportion = 50; /* % of threads that may process
-					     * very slow work */
-
-#ifdef CONFIG_SYSCTL
-static const int slow_work_min_min_threads = 2;
-static int slow_work_max_max_threads = SLOW_WORK_THREAD_LIMIT;
-static const int slow_work_min_vslow = 1;
-static const int slow_work_max_vslow = 99;
-
-ctl_table slow_work_sysctls[] = {
-	{
-		.procname	= "min-threads",
-		.data		= &slow_work_min_threads,
-		.maxlen		= sizeof(unsigned),
-		.mode		= 0644,
-		.proc_handler	= slow_work_min_threads_sysctl,
-		.extra1		= (void *) &slow_work_min_min_threads,
-		.extra2		= &slow_work_max_threads,
-	},
-	{
-		.procname	= "max-threads",
-		.data		= &slow_work_max_threads,
-		.maxlen		= sizeof(unsigned),
-		.mode		= 0644,
-		.proc_handler	= slow_work_max_threads_sysctl,
-		.extra1		= &slow_work_min_threads,
-		.extra2		= (void *) &slow_work_max_max_threads,
-	},
-	{
-		.procname	= "vslow-percentage",
-		.data		= &vslow_work_proportion,
-		.maxlen		= sizeof(unsigned),
-		.mode		= 0644,
-		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= (void *) &slow_work_min_vslow,
-		.extra2		= (void *) &slow_work_max_vslow,
-	},
-	{}
-};
-#endif
-
-/*
- * The active state of the thread pool
- */
-static atomic_t slow_work_thread_count;
-static atomic_t vslow_work_executing_count;
-
-static bool slow_work_may_not_start_new_thread;
-static bool slow_work_cull; /* cull a thread due to lack of activity */
-static DEFINE_TIMER(slow_work_cull_timer, slow_work_cull_timeout, 0, 0);
-static DEFINE_TIMER(slow_work_oom_timer, slow_work_oom_timeout, 0, 0);
-static struct slow_work slow_work_new_thread; /* new thread starter */
-
-/*
- * slow work ID allocation (use slow_work_queue_lock)
- */
-static DECLARE_BITMAP(slow_work_ids, SLOW_WORK_THREAD_LIMIT);
-
-/*
- * Unregistration tracking to prevent put_ref() from disappearing during module
- * unload
- */
-#ifdef CONFIG_MODULES
-static struct module *slow_work_thread_processing[SLOW_WORK_THREAD_LIMIT];
-static struct module *slow_work_unreg_module;
-static struct slow_work *slow_work_unreg_work_item;
-static DECLARE_WAIT_QUEUE_HEAD(slow_work_unreg_wq);
-static DEFINE_MUTEX(slow_work_unreg_sync_lock);
-
-static void slow_work_set_thread_processing(int id, struct slow_work *work)
-{
-	if (work)
-		slow_work_thread_processing[id] = work->owner;
-}
-static void slow_work_done_thread_processing(int id, struct slow_work *work)
-{
-	struct module *module = slow_work_thread_processing[id];
-
-	slow_work_thread_processing[id] = NULL;
-	smp_mb();
-	if (slow_work_unreg_work_item == work ||
-	    slow_work_unreg_module == module)
-		wake_up_all(&slow_work_unreg_wq);
-}
-static void slow_work_clear_thread_processing(int id)
-{
-	slow_work_thread_processing[id] = NULL;
-}
-#else
-static void slow_work_set_thread_processing(int id, struct slow_work *work) {}
-static void slow_work_done_thread_processing(int id, struct slow_work *work) {}
-static void slow_work_clear_thread_processing(int id) {}
-#endif
-
-/*
- * Data for tracking currently executing items for indication through /proc
- */
-#ifdef CONFIG_SLOW_WORK_DEBUG
-struct slow_work *slow_work_execs[SLOW_WORK_THREAD_LIMIT];
-pid_t slow_work_pids[SLOW_WORK_THREAD_LIMIT];
-DEFINE_RWLOCK(slow_work_execs_lock);
-#endif
-
-/*
- * The queues of work items and the lock governing access to them.  These are
- * shared between all the CPUs.  It doesn't make sense to have per-CPU queues
- * as the number of threads bears no relation to the number of CPUs.
- *
- * There are two queues of work items: one for slow work items, and one for
- * very slow work items.
- */
-LIST_HEAD(slow_work_queue);
-LIST_HEAD(vslow_work_queue);
-DEFINE_SPINLOCK(slow_work_queue_lock);
-
-/*
- * The following are two wait queues that get pinged when a work item is placed
- * on an empty queue.  These allow work items that are hogging a thread by
- * sleeping in a way that could be deferred to yield their thread and enqueue
- * themselves.
- */
-static DECLARE_WAIT_QUEUE_HEAD(slow_work_queue_waits_for_occupation);
-static DECLARE_WAIT_QUEUE_HEAD(vslow_work_queue_waits_for_occupation);
-
-/*
- * The thread controls.  A variable used to signal to the threads that they
- * should exit when the queue is empty, a waitqueue used by the threads to wait
- * for signals, and a completion set by the last thread to exit.
- */
-static bool slow_work_threads_should_exit;
-static DECLARE_WAIT_QUEUE_HEAD(slow_work_thread_wq);
-static DECLARE_COMPLETION(slow_work_last_thread_exited);
-
-/*
- * The number of users of the thread pool and its lock.  Whilst this is zero we
- * have no threads hanging around, and when this reaches zero, we wait for all
- * active or queued work items to complete and kill all the threads we do have.
- */
-static int slow_work_user_count;
-static DEFINE_MUTEX(slow_work_user_lock);
-
-static inline int slow_work_get_ref(struct slow_work *work)
-{
-	if (work->ops->get_ref)
-		return work->ops->get_ref(work);
-
-	return 0;
-}
-
-static inline void slow_work_put_ref(struct slow_work *work)
-{
-	if (work->ops->put_ref)
-		work->ops->put_ref(work);
-}
-
-/*
- * Calculate the maximum number of active threads in the pool that are
- * permitted to process very slow work items.
- *
- * The answer is rounded up to at least 1, but may not equal or exceed the
- * maximum number of the threads in the pool.  This means we always have at
- * least one thread that can process slow work items, and we always have at
- * least one thread that won't get tied up doing so.
- */
-static unsigned slow_work_calc_vsmax(void)
-{
-	unsigned vsmax;
-
-	vsmax = atomic_read(&slow_work_thread_count) * vslow_work_proportion;
-	vsmax /= 100;
-	vsmax = max(vsmax, 1U);
-	return min(vsmax, slow_work_max_threads - 1);
-}
-
-/*
- * Attempt to execute stuff queued on a slow thread.  Return true if we managed
- * it, false if there was nothing to do.
- */
-static noinline bool slow_work_execute(int id)
-{
-	struct slow_work *work = NULL;
-	unsigned vsmax;
-	bool very_slow;
-
-	vsmax = slow_work_calc_vsmax();
-
-	/* see if we can schedule a new thread to be started if we're not
-	 * keeping up with the work */
-	if (!waitqueue_active(&slow_work_thread_wq) &&
-	    (!list_empty(&slow_work_queue) || !list_empty(&vslow_work_queue)) &&
-	    atomic_read(&slow_work_thread_count) < slow_work_max_threads &&
-	    !slow_work_may_not_start_new_thread)
-		slow_work_enqueue(&slow_work_new_thread);
-
-	/* find something to execute */
-	spin_lock_irq(&slow_work_queue_lock);
-	if (!list_empty(&vslow_work_queue) &&
-	    atomic_read(&vslow_work_executing_count) < vsmax) {
-		work = list_entry(vslow_work_queue.next,
-				  struct slow_work, link);
-		if (test_and_set_bit_lock(SLOW_WORK_EXECUTING, &work->flags))
-			BUG();
-		list_del_init(&work->link);
-		atomic_inc(&vslow_work_executing_count);
-		very_slow = true;
-	} else if (!list_empty(&slow_work_queue)) {
-		work = list_entry(slow_work_queue.next,
-				  struct slow_work, link);
-		if (test_and_set_bit_lock(SLOW_WORK_EXECUTING, &work->flags))
-			BUG();
-		list_del_init(&work->link);
-		very_slow = false;
-	} else {
-		very_slow = false; /* avoid the compiler warning */
-	}
-
-	slow_work_set_thread_processing(id, work);
-	if (work) {
-		slow_work_mark_time(work);
-		slow_work_begin_exec(id, work);
-	}
-
-	spin_unlock_irq(&slow_work_queue_lock);
-
-	if (!work)
-		return false;
-
-	if (!test_and_clear_bit(SLOW_WORK_PENDING, &work->flags))
-		BUG();
-
-	/* don't execute if the work is in the process of being cancelled */
-	if (!test_bit(SLOW_WORK_CANCELLING, &work->flags))
-		work->ops->execute(work);
-
-	if (very_slow)
-		atomic_dec(&vslow_work_executing_count);
-	clear_bit_unlock(SLOW_WORK_EXECUTING, &work->flags);
-
-	/* wake up anyone waiting for this work to be complete */
-	wake_up_bit(&work->flags, SLOW_WORK_EXECUTING);
-
-	slow_work_end_exec(id, work);
-
-	/* if someone tried to enqueue the item whilst we were executing it,
-	 * then it'll be left unenqueued to avoid multiple threads trying to
-	 * execute it simultaneously
-	 *
-	 * there is, however, a race between us testing the pending flag and
-	 * getting the spinlock, and between the enqueuer setting the pending
-	 * flag and getting the spinlock, so we use a deferral bit to tell us
-	 * if the enqueuer got there first
-	 */
-	if (test_bit(SLOW_WORK_PENDING, &work->flags)) {
-		spin_lock_irq(&slow_work_queue_lock);
-
-		if (!test_bit(SLOW_WORK_EXECUTING, &work->flags) &&
-		    test_and_clear_bit(SLOW_WORK_ENQ_DEFERRED, &work->flags))
-			goto auto_requeue;
-
-		spin_unlock_irq(&slow_work_queue_lock);
-	}
-
-	/* sort out the race between module unloading and put_ref() */
-	slow_work_put_ref(work);
-	slow_work_done_thread_processing(id, work);
-
-	return true;
-
-auto_requeue:
-	/* we must complete the enqueue operation
-	 * - we transfer our ref on the item back to the appropriate queue
-	 * - don't wake another thread up as we're awake already
-	 */
-	slow_work_mark_time(work);
-	if (test_bit(SLOW_WORK_VERY_SLOW, &work->flags))
-		list_add_tail(&work->link, &vslow_work_queue);
-	else
-		list_add_tail(&work->link, &slow_work_queue);
-	spin_unlock_irq(&slow_work_queue_lock);
-	slow_work_clear_thread_processing(id);
-	return true;
-}
-
-/**
- * slow_work_sleep_till_thread_needed - Sleep till thread needed by other work
- * work: The work item under execution that wants to sleep
- * _timeout: Scheduler sleep timeout
- *
- * Allow a requeueable work item to sleep on a slow-work processor thread until
- * that thread is needed to do some other work or the sleep is interrupted by
- * some other event.
- *
- * The caller must set up a wake up event before calling this and must have set
- * the appropriate sleep mode (such as TASK_UNINTERRUPTIBLE) and tested its own
- * condition before calling this function as no test is made here.
- *
- * False is returned if there is nothing on the queue; true is returned if the
- * work item should be requeued
- */
-bool slow_work_sleep_till_thread_needed(struct slow_work *work,
-					signed long *_timeout)
-{
-	wait_queue_head_t *wfo_wq;
-	struct list_head *queue;
-
-	DEFINE_WAIT(wait);
-
-	if (test_bit(SLOW_WORK_VERY_SLOW, &work->flags)) {
-		wfo_wq = &vslow_work_queue_waits_for_occupation;
-		queue = &vslow_work_queue;
-	} else {
-		wfo_wq = &slow_work_queue_waits_for_occupation;
-		queue = &slow_work_queue;
-	}
-
-	if (!list_empty(queue))
-		return true;
-
-	add_wait_queue_exclusive(wfo_wq, &wait);
-	if (list_empty(queue))
-		*_timeout = schedule_timeout(*_timeout);
-	finish_wait(wfo_wq, &wait);
-
-	return !list_empty(queue);
-}
-EXPORT_SYMBOL(slow_work_sleep_till_thread_needed);
-
-/**
- * slow_work_enqueue - Schedule a slow work item for processing
- * @work: The work item to queue
- *
- * Schedule a slow work item for processing.  If the item is already undergoing
- * execution, this guarantees not to re-enter the execution routine until the
- * first execution finishes.
- *
- * The item is pinned by this function as it retains a reference to it, managed
- * through the item operations.  The item is unpinned once it has been
- * executed.
- *
- * An item may hog the thread that is running it for a relatively large amount
- * of time, sufficient, for example, to perform several lookup, mkdir, create
- * and setxattr operations.  It may sleep on I/O and may sleep to obtain locks.
- *
- * Conversely, if a number of items are awaiting processing, it may take some
- * time before any given item is given attention.  The number of threads in the
- * pool may be increased to deal with demand, but only up to a limit.
- *
- * If SLOW_WORK_VERY_SLOW is set on the work item, then it will be placed in
- * the very slow queue, from which only a portion of the threads will be
- * allowed to pick items to execute.  This ensures that very slow items won't
- * overly block ones that are just ordinarily slow.
- *
- * Returns 0 if successful, -EAGAIN if not (or -ECANCELED if cancelled work is
- * attempted queued)
- */
-int slow_work_enqueue(struct slow_work *work)
-{
-	wait_queue_head_t *wfo_wq;
-	struct list_head *queue;
-	unsigned long flags;
-	int ret;
-
-	if (test_bit(SLOW_WORK_CANCELLING, &work->flags))
-		return -ECANCELED;
-
-	BUG_ON(slow_work_user_count <= 0);
-	BUG_ON(!work);
-	BUG_ON(!work->ops);
-
-	/* when honouring an enqueue request, we only promise that we will run
-	 * the work function in the future; we do not promise to run it once
-	 * per enqueue request
-	 *
-	 * we use the PENDING bit to merge together repeat requests without
-	 * having to disable IRQs and take the spinlock, whilst still
-	 * maintaining our promise
-	 */
-	if (!test_and_set_bit_lock(SLOW_WORK_PENDING, &work->flags)) {
-		if (test_bit(SLOW_WORK_VERY_SLOW, &work->flags)) {
-			wfo_wq = &vslow_work_queue_waits_for_occupation;
-			queue = &vslow_work_queue;
-		} else {
-			wfo_wq = &slow_work_queue_waits_for_occupation;
-			queue = &slow_work_queue;
-		}
-
-		spin_lock_irqsave(&slow_work_queue_lock, flags);
-
-		if (unlikely(test_bit(SLOW_WORK_CANCELLING, &work->flags)))
-			goto cancelled;
-
-		/* we promise that we will not attempt to execute the work
-		 * function in more than one thread simultaneously
-		 *
-		 * this, however, leaves us with a problem if we're asked to
-		 * enqueue the work whilst someone is executing the work
-		 * function as simply queueing the work immediately means that
-		 * another thread may try executing it whilst it is already
-		 * under execution
-		 *
-		 * to deal with this, we set the ENQ_DEFERRED bit instead of
-		 * enqueueing, and the thread currently executing the work
-		 * function will enqueue the work item when the work function
-		 * returns and it has cleared the EXECUTING bit
-		 */
-		if (test_bit(SLOW_WORK_EXECUTING, &work->flags)) {
-			set_bit(SLOW_WORK_ENQ_DEFERRED, &work->flags);
-		} else {
-			ret = slow_work_get_ref(work);
-			if (ret < 0)
-				goto failed;
-			slow_work_mark_time(work);
-			list_add_tail(&work->link, queue);
-			wake_up(&slow_work_thread_wq);
-
-			/* if someone who could be requeued is sleeping on a
-			 * thread, then ask them to yield their thread */
-			if (work->link.prev == queue)
-				wake_up(wfo_wq);
-		}
-
-		spin_unlock_irqrestore(&slow_work_queue_lock, flags);
-	}
-	return 0;
-
-cancelled:
-	ret = -ECANCELED;
-failed:
-	spin_unlock_irqrestore(&slow_work_queue_lock, flags);
-	return ret;
-}
-EXPORT_SYMBOL(slow_work_enqueue);
-
-static int slow_work_wait(void *word)
-{
-	schedule();
-	return 0;
-}
-
-/**
- * slow_work_cancel - Cancel a slow work item
- * @work: The work item to cancel
- *
- * This function will cancel a previously enqueued work item. If we cannot
- * cancel the work item, it is guarenteed to have run when this function
- * returns.
- */
-void slow_work_cancel(struct slow_work *work)
-{
-	bool wait = true, put = false;
-
-	set_bit(SLOW_WORK_CANCELLING, &work->flags);
-	smp_mb();
-
-	/* if the work item is a delayed work item with an active timer, we
-	 * need to wait for the timer to finish _before_ getting the spinlock,
-	 * lest we deadlock against the timer routine
-	 *
-	 * the timer routine will leave DELAYED set if it notices the
-	 * CANCELLING flag in time
-	 */
-	if (test_bit(SLOW_WORK_DELAYED, &work->flags)) {
-		struct delayed_slow_work *dwork =
-			container_of(work, struct delayed_slow_work, work);
-		del_timer_sync(&dwork->timer);
-	}
-
-	spin_lock_irq(&slow_work_queue_lock);
-
-	if (test_bit(SLOW_WORK_DELAYED, &work->flags)) {
-		/* the timer routine aborted or never happened, so we are left
-		 * holding the timer's reference on the item and should just
-		 * drop the pending flag and wait for any ongoing execution to
-		 * finish */
-		struct delayed_slow_work *dwork =
-			container_of(work, struct delayed_slow_work, work);
-
-		BUG_ON(timer_pending(&dwork->timer));
-		BUG_ON(!list_empty(&work->link));
-
-		clear_bit(SLOW_WORK_DELAYED, &work->flags);
-		put = true;
-		clear_bit(SLOW_WORK_PENDING, &work->flags);
-
-	} else if (test_bit(SLOW_WORK_PENDING, &work->flags) &&
-		   !list_empty(&work->link)) {
-		/* the link in the pending queue holds a reference on the item
-		 * that we will need to release */
-		list_del_init(&work->link);
-		wait = false;
-		put = true;
-		clear_bit(SLOW_WORK_PENDING, &work->flags);
-
-	} else if (test_and_clear_bit(SLOW_WORK_ENQ_DEFERRED, &work->flags)) {
-		/* the executor is holding our only reference on the item, so
-		 * we merely need to wait for it to finish executing */
-		clear_bit(SLOW_WORK_PENDING, &work->flags);
-	}
-
-	spin_unlock_irq(&slow_work_queue_lock);
-
-	/* the EXECUTING flag is set by the executor whilst the spinlock is set
-	 * and before the item is dequeued - so assuming the above doesn't
-	 * actually dequeue it, simply waiting for the EXECUTING flag to be
-	 * released here should be sufficient */
-	if (wait)
-		wait_on_bit(&work->flags, SLOW_WORK_EXECUTING, slow_work_wait,
-			    TASK_UNINTERRUPTIBLE);
-
-	clear_bit(SLOW_WORK_CANCELLING, &work->flags);
-	if (put)
-		slow_work_put_ref(work);
-}
-EXPORT_SYMBOL(slow_work_cancel);
-
-/*
- * Handle expiry of the delay timer, indicating that a delayed slow work item
- * should now be queued if not cancelled
- */
-static void delayed_slow_work_timer(unsigned long data)
-{
-	wait_queue_head_t *wfo_wq;
-	struct list_head *queue;
-	struct slow_work *work = (struct slow_work *) data;
-	unsigned long flags;
-	bool queued = false, put = false, first = false;
-
-	if (test_bit(SLOW_WORK_VERY_SLOW, &work->flags)) {
-		wfo_wq = &vslow_work_queue_waits_for_occupation;
-		queue = &vslow_work_queue;
-	} else {
-		wfo_wq = &slow_work_queue_waits_for_occupation;
-		queue = &slow_work_queue;
-	}
-
-	spin_lock_irqsave(&slow_work_queue_lock, flags);
-	if (likely(!test_bit(SLOW_WORK_CANCELLING, &work->flags))) {
-		clear_bit(SLOW_WORK_DELAYED, &work->flags);
-
-		if (test_bit(SLOW_WORK_EXECUTING, &work->flags)) {
-			/* we discard the reference the timer was holding in
-			 * favour of the one the executor holds */
-			set_bit(SLOW_WORK_ENQ_DEFERRED, &work->flags);
-			put = true;
-		} else {
-			slow_work_mark_time(work);
-			list_add_tail(&work->link, queue);
-			queued = true;
-			if (work->link.prev == queue)
-				first = true;
-		}
-	}
-
-	spin_unlock_irqrestore(&slow_work_queue_lock, flags);
-	if (put)
-		slow_work_put_ref(work);
-	if (first)
-		wake_up(wfo_wq);
-	if (queued)
-		wake_up(&slow_work_thread_wq);
-}
-
-/**
- * delayed_slow_work_enqueue - Schedule a delayed slow work item for processing
- * @dwork: The delayed work item to queue
- * @delay: When to start executing the work, in jiffies from now
- *
- * This is similar to slow_work_enqueue(), but it adds a delay before the work
- * is actually queued for processing.
- *
- * The item can have delayed processing requested on it whilst it is being
- * executed.  The delay will begin immediately, and if it expires before the
- * item finishes executing, the item will be placed back on the queue when it
- * has done executing.
- */
-int delayed_slow_work_enqueue(struct delayed_slow_work *dwork,
-			      unsigned long delay)
-{
-	struct slow_work *work = &dwork->work;
-	unsigned long flags;
-	int ret;
-
-	if (delay == 0)
-		return slow_work_enqueue(&dwork->work);
-
-	BUG_ON(slow_work_user_count <= 0);
-	BUG_ON(!work);
-	BUG_ON(!work->ops);
-
-	if (test_bit(SLOW_WORK_CANCELLING, &work->flags))
-		return -ECANCELED;
-
-	if (!test_and_set_bit_lock(SLOW_WORK_PENDING, &work->flags)) {
-		spin_lock_irqsave(&slow_work_queue_lock, flags);
-
-		if (test_bit(SLOW_WORK_CANCELLING, &work->flags))
-			goto cancelled;
-
-		/* the timer holds a reference whilst it is pending */
-		ret = slow_work_get_ref(work);
-		if (ret < 0)
-			goto cant_get_ref;
-
-		if (test_and_set_bit(SLOW_WORK_DELAYED, &work->flags))
-			BUG();
-		dwork->timer.expires = jiffies + delay;
-		dwork->timer.data = (unsigned long) work;
-		dwork->timer.function = delayed_slow_work_timer;
-		add_timer(&dwork->timer);
-
-		spin_unlock_irqrestore(&slow_work_queue_lock, flags);
-	}
-
-	return 0;
-
-cancelled:
-	ret = -ECANCELED;
-cant_get_ref:
-	spin_unlock_irqrestore(&slow_work_queue_lock, flags);
-	return ret;
-}
-EXPORT_SYMBOL(delayed_slow_work_enqueue);
-
-/*
- * Schedule a cull of the thread pool at some time in the near future
- */
-static void slow_work_schedule_cull(void)
-{
-	mod_timer(&slow_work_cull_timer,
-		  round_jiffies(jiffies + SLOW_WORK_CULL_TIMEOUT));
-}
-
-/*
- * Worker thread culling algorithm
- */
-static bool slow_work_cull_thread(void)
-{
-	unsigned long flags;
-	bool do_cull = false;
-
-	spin_lock_irqsave(&slow_work_queue_lock, flags);
-
-	if (slow_work_cull) {
-		slow_work_cull = false;
-
-		if (list_empty(&slow_work_queue) &&
-		    list_empty(&vslow_work_queue) &&
-		    atomic_read(&slow_work_thread_count) >
-		    slow_work_min_threads) {
-			slow_work_schedule_cull();
-			do_cull = true;
-		}
-	}
-
-	spin_unlock_irqrestore(&slow_work_queue_lock, flags);
-	return do_cull;
-}
-
-/*
- * Determine if there is slow work available for dispatch
- */
-static inline bool slow_work_available(int vsmax)
-{
-	return !list_empty(&slow_work_queue) ||
-		(!list_empty(&vslow_work_queue) &&
-		 atomic_read(&vslow_work_executing_count) < vsmax);
-}
-
-/*
- * Worker thread dispatcher
- */
-static int slow_work_thread(void *_data)
-{
-	int vsmax, id;
-
-	DEFINE_WAIT(wait);
-
-	set_freezable();
-	set_user_nice(current, -5);
-
-	/* allocate ourselves an ID */
-	spin_lock_irq(&slow_work_queue_lock);
-	id = find_first_zero_bit(slow_work_ids, SLOW_WORK_THREAD_LIMIT);
-	BUG_ON(id < 0 || id >= SLOW_WORK_THREAD_LIMIT);
-	__set_bit(id, slow_work_ids);
-	slow_work_set_thread_pid(id, current->pid);
-	spin_unlock_irq(&slow_work_queue_lock);
-
-	sprintf(current->comm, "kslowd%03u", id);
-
-	for (;;) {
-		vsmax = vslow_work_proportion;
-		vsmax *= atomic_read(&slow_work_thread_count);
-		vsmax /= 100;
-
-		prepare_to_wait_exclusive(&slow_work_thread_wq, &wait,
-					  TASK_INTERRUPTIBLE);
-		if (!freezing(current) &&
-		    !slow_work_threads_should_exit &&
-		    !slow_work_available(vsmax) &&
-		    !slow_work_cull)
-			schedule();
-		finish_wait(&slow_work_thread_wq, &wait);
-
-		try_to_freeze();
-
-		vsmax = vslow_work_proportion;
-		vsmax *= atomic_read(&slow_work_thread_count);
-		vsmax /= 100;
-
-		if (slow_work_available(vsmax) && slow_work_execute(id)) {
-			cond_resched();
-			if (list_empty(&slow_work_queue) &&
-			    list_empty(&vslow_work_queue) &&
-			    atomic_read(&slow_work_thread_count) >
-			    slow_work_min_threads)
-				slow_work_schedule_cull();
-			continue;
-		}
-
-		if (slow_work_threads_should_exit)
-			break;
-
-		if (slow_work_cull && slow_work_cull_thread())
-			break;
-	}
-
-	spin_lock_irq(&slow_work_queue_lock);
-	slow_work_set_thread_pid(id, 0);
-	__clear_bit(id, slow_work_ids);
-	spin_unlock_irq(&slow_work_queue_lock);
-
-	if (atomic_dec_and_test(&slow_work_thread_count))
-		complete_and_exit(&slow_work_last_thread_exited, 0);
-	return 0;
-}
-
-/*
- * Handle thread cull timer expiration
- */
-static void slow_work_cull_timeout(unsigned long data)
-{
-	slow_work_cull = true;
-	wake_up(&slow_work_thread_wq);
-}
-
-/*
- * Start a new slow work thread
- */
-static void slow_work_new_thread_execute(struct slow_work *work)
-{
-	struct task_struct *p;
-
-	if (slow_work_threads_should_exit)
-		return;
-
-	if (atomic_read(&slow_work_thread_count) >= slow_work_max_threads)
-		return;
-
-	if (!mutex_trylock(&slow_work_user_lock))
-		return;
-
-	slow_work_may_not_start_new_thread = true;
-	atomic_inc(&slow_work_thread_count);
-	p = kthread_run(slow_work_thread, NULL, "kslowd");
-	if (IS_ERR(p)) {
-		printk(KERN_DEBUG "Slow work thread pool: OOM\n");
-		if (atomic_dec_and_test(&slow_work_thread_count))
-			BUG(); /* we're running on a slow work thread... */
-		mod_timer(&slow_work_oom_timer,
-			  round_jiffies(jiffies + SLOW_WORK_OOM_TIMEOUT));
-	} else {
-		/* ratelimit the starting of new threads */
-		mod_timer(&slow_work_oom_timer, jiffies + 1);
-	}
-
-	mutex_unlock(&slow_work_user_lock);
-}
-
-static const struct slow_work_ops slow_work_new_thread_ops = {
-	.owner		= THIS_MODULE,
-	.execute	= slow_work_new_thread_execute,
-#ifdef CONFIG_SLOW_WORK_DEBUG
-	.desc		= slow_work_new_thread_desc,
-#endif
-};
-
-/*
- * post-OOM new thread start suppression expiration
- */
-static void slow_work_oom_timeout(unsigned long data)
-{
-	slow_work_may_not_start_new_thread = false;
-}
-
-#ifdef CONFIG_SYSCTL
-/*
- * Handle adjustment of the minimum number of threads
- */
-static int slow_work_min_threads_sysctl(struct ctl_table *table, int write,
-					void __user *buffer,
-					size_t *lenp, loff_t *ppos)
-{
-	int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
-	int n;
-
-	if (ret == 0) {
-		mutex_lock(&slow_work_user_lock);
-		if (slow_work_user_count > 0) {
-			/* see if we need to start or stop threads */
-			n = atomic_read(&slow_work_thread_count) -
-				slow_work_min_threads;
-
-			if (n < 0 && !slow_work_may_not_start_new_thread)
-				slow_work_enqueue(&slow_work_new_thread);
-			else if (n > 0)
-				slow_work_schedule_cull();
-		}
-		mutex_unlock(&slow_work_user_lock);
-	}
-
-	return ret;
-}
-
-/*
- * Handle adjustment of the maximum number of threads
- */
-static int slow_work_max_threads_sysctl(struct ctl_table *table, int write,
-					void __user *buffer,
-					size_t *lenp, loff_t *ppos)
-{
-	int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
-	int n;
-
-	if (ret == 0) {
-		mutex_lock(&slow_work_user_lock);
-		if (slow_work_user_count > 0) {
-			/* see if we need to stop threads */
-			n = slow_work_max_threads -
-				atomic_read(&slow_work_thread_count);
-
-			if (n < 0)
-				slow_work_schedule_cull();
-		}
-		mutex_unlock(&slow_work_user_lock);
-	}
-
-	return ret;
-}
-#endif /* CONFIG_SYSCTL */
-
-/**
- * slow_work_register_user - Register a user of the facility
- * @module: The module about to make use of the facility
- *
- * Register a user of the facility, starting up the initial threads if there
- * aren't any other users at this point.  This will return 0 if successful, or
- * an error if not.
- */
-int slow_work_register_user(struct module *module)
-{
-	struct task_struct *p;
-	int loop;
-
-	mutex_lock(&slow_work_user_lock);
-
-	if (slow_work_user_count == 0) {
-		printk(KERN_NOTICE "Slow work thread pool: Starting up\n");
-		init_completion(&slow_work_last_thread_exited);
-
-		slow_work_threads_should_exit = false;
-		slow_work_init(&slow_work_new_thread,
-			       &slow_work_new_thread_ops);
-		slow_work_may_not_start_new_thread = false;
-		slow_work_cull = false;
-
-		/* start the minimum number of threads */
-		for (loop = 0; loop < slow_work_min_threads; loop++) {
-			atomic_inc(&slow_work_thread_count);
-			p = kthread_run(slow_work_thread, NULL, "kslowd");
-			if (IS_ERR(p))
-				goto error;
-		}
-		printk(KERN_NOTICE "Slow work thread pool: Ready\n");
-	}
-
-	slow_work_user_count++;
-	mutex_unlock(&slow_work_user_lock);
-	return 0;
-
-error:
-	if (atomic_dec_and_test(&slow_work_thread_count))
-		complete(&slow_work_last_thread_exited);
-	if (loop > 0) {
-		printk(KERN_ERR "Slow work thread pool:"
-		       " Aborting startup on ENOMEM\n");
-		slow_work_threads_should_exit = true;
-		wake_up_all(&slow_work_thread_wq);
-		wait_for_completion(&slow_work_last_thread_exited);
-		printk(KERN_ERR "Slow work thread pool: Aborted\n");
-	}
-	mutex_unlock(&slow_work_user_lock);
-	return PTR_ERR(p);
-}
-EXPORT_SYMBOL(slow_work_register_user);
-
-/*
- * wait for all outstanding items from the calling module to complete
- * - note that more items may be queued whilst we're waiting
- */
-static void slow_work_wait_for_items(struct module *module)
-{
-#ifdef CONFIG_MODULES
-	DECLARE_WAITQUEUE(myself, current);
-	struct slow_work *work;
-	int loop;
-
-	mutex_lock(&slow_work_unreg_sync_lock);
-	add_wait_queue(&slow_work_unreg_wq, &myself);
-
-	for (;;) {
-		spin_lock_irq(&slow_work_queue_lock);
-
-		/* first of all, we wait for the last queued item in each list
-		 * to be processed */
-		list_for_each_entry_reverse(work, &vslow_work_queue, link) {
-			if (work->owner == module) {
-				set_current_state(TASK_UNINTERRUPTIBLE);
-				slow_work_unreg_work_item = work;
-				goto do_wait;
-			}
-		}
-		list_for_each_entry_reverse(work, &slow_work_queue, link) {
-			if (work->owner == module) {
-				set_current_state(TASK_UNINTERRUPTIBLE);
-				slow_work_unreg_work_item = work;
-				goto do_wait;
-			}
-		}
-
-		/* then we wait for the items being processed to finish */
-		slow_work_unreg_module = module;
-		smp_mb();
-		for (loop = 0; loop < SLOW_WORK_THREAD_LIMIT; loop++) {
-			if (slow_work_thread_processing[loop] == module)
-				goto do_wait;
-		}
-		spin_unlock_irq(&slow_work_queue_lock);
-		break; /* okay, we're done */
-
-	do_wait:
-		spin_unlock_irq(&slow_work_queue_lock);
-		schedule();
-		slow_work_unreg_work_item = NULL;
-		slow_work_unreg_module = NULL;
-	}
-
-	remove_wait_queue(&slow_work_unreg_wq, &myself);
-	mutex_unlock(&slow_work_unreg_sync_lock);
-#endif /* CONFIG_MODULES */
-}
-
-/**
- * slow_work_unregister_user - Unregister a user of the facility
- * @module: The module whose items should be cleared
- *
- * Unregister a user of the facility, killing all the threads if this was the
- * last one.
- *
- * This waits for all the work items belonging to the nominated module to go
- * away before proceeding.
- */
-void slow_work_unregister_user(struct module *module)
-{
-	/* first of all, wait for all outstanding items from the calling module
-	 * to complete */
-	if (module)
-		slow_work_wait_for_items(module);
-
-	/* then we can actually go about shutting down the facility if need
-	 * be */
-	mutex_lock(&slow_work_user_lock);
-
-	BUG_ON(slow_work_user_count <= 0);
-
-	slow_work_user_count--;
-	if (slow_work_user_count == 0) {
-		printk(KERN_NOTICE "Slow work thread pool: Shutting down\n");
-		slow_work_threads_should_exit = true;
-		del_timer_sync(&slow_work_cull_timer);
-		del_timer_sync(&slow_work_oom_timer);
-		wake_up_all(&slow_work_thread_wq);
-		wait_for_completion(&slow_work_last_thread_exited);
-		printk(KERN_NOTICE "Slow work thread pool:"
-		       " Shut down complete\n");
-	}
-
-	mutex_unlock(&slow_work_user_lock);
-}
-EXPORT_SYMBOL(slow_work_unregister_user);
-
-/*
- * Initialise the slow work facility
- */
-static int __init init_slow_work(void)
-{
-	unsigned nr_cpus = num_possible_cpus();
-
-	if (slow_work_max_threads < nr_cpus)
-		slow_work_max_threads = nr_cpus;
-#ifdef CONFIG_SYSCTL
-	if (slow_work_max_max_threads < nr_cpus * 2)
-		slow_work_max_max_threads = nr_cpus * 2;
-#endif
-#ifdef CONFIG_SLOW_WORK_DEBUG
-	{
-		struct dentry *dbdir;
-
-		dbdir = debugfs_create_dir("slow_work", NULL);
-		if (dbdir && !IS_ERR(dbdir))
-			debugfs_create_file("runqueue", S_IFREG | 0400, dbdir,
-					    NULL, &slow_work_runqueue_fops);
-	}
-#endif
-	return 0;
-}
-
-subsys_initcall(init_slow_work);

kernel/slow-work.h

@@ -1,72 +0,0 @@
-/* Slow work private definitions
- *
- * Copyright (C) 2009 Red Hat, Inc. All Rights Reserved.
- * Written by David Howells (dhowells@redhat.com)
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public Licence
- * as published by the Free Software Foundation; either version
- * 2 of the Licence, or (at your option) any later version.
- */
-
-#define SLOW_WORK_CULL_TIMEOUT (5 * HZ)	/* cull threads 5s after running out of
-					 * things to do */
-#define SLOW_WORK_OOM_TIMEOUT (5 * HZ)	/* can't start new threads for 5s after
-					 * OOM */
-
-#define SLOW_WORK_THREAD_LIMIT	255	/* abs maximum number of slow-work threads */
-
-/*
- * slow-work.c
- */
-#ifdef CONFIG_SLOW_WORK_DEBUG
-extern struct slow_work *slow_work_execs[];
-extern pid_t slow_work_pids[];
-extern rwlock_t slow_work_execs_lock;
-#endif
-
-extern struct list_head slow_work_queue;
-extern struct list_head vslow_work_queue;
-extern spinlock_t slow_work_queue_lock;
-
-/*
- * slow-work-debugfs.c
- */
-#ifdef CONFIG_SLOW_WORK_DEBUG
-extern const struct file_operations slow_work_runqueue_fops;
-
-extern void slow_work_new_thread_desc(struct slow_work *, struct seq_file *);
-#endif
-
-/*
- * Helper functions
- */
-static inline void slow_work_set_thread_pid(int id, pid_t pid)
-{
-#ifdef CONFIG_SLOW_WORK_DEBUG
-	slow_work_pids[id] = pid;
-#endif
-}
-
-static inline void slow_work_mark_time(struct slow_work *work)
-{
-#ifdef CONFIG_SLOW_WORK_DEBUG
-	work->mark = CURRENT_TIME;
-#endif
-}
-
-static inline void slow_work_begin_exec(int id, struct slow_work *work)
-{
-#ifdef CONFIG_SLOW_WORK_DEBUG
-	slow_work_execs[id] = work;
-#endif
-}
-
-static inline void slow_work_end_exec(int id, struct slow_work *work)
-{
-#ifdef CONFIG_SLOW_WORK_DEBUG
-	write_lock(&slow_work_execs_lock);
-	slow_work_execs[id] = NULL;
-	write_unlock(&slow_work_execs_lock);
-#endif
-}

kernel/sysctl.c

@@ -50,7 +50,6 @@
 #include <linux/acpi.h>
 #include <linux/reboot.h>
 #include <linux/ftrace.h>
-#include <linux/slow-work.h>
 #include <linux/perf_event.h>
 #include <linux/kprobes.h>
 #include <linux/pipe_fs_i.h>
@@ -917,13 +916,6 @@ static struct ctl_table kern_table[] = {
 		.proc_handler	= proc_dointvec,
 	},
 #endif
-#ifdef CONFIG_SLOW_WORK
-	{
-		.procname	= "slow-work",
-		.mode		= 0555,
-		.child		= slow_work_sysctls,
-	},
-#endif
 #ifdef CONFIG_PERF_EVENTS
 	{
 		.procname	= "perf_event_paranoid",

kernel/trace/Kconfig

@@ -323,17 +323,6 @@ config STACK_TRACER
 
 	  Say N if unsure.
 
-config WORKQUEUE_TRACER
-	bool "Trace workqueues"
-	select GENERIC_TRACER
-	help
-	  The workqueue tracer provides some statistical information
-          about each cpu workqueue thread such as the number of the
-          works inserted and executed since their creation. It can help
-          to evaluate the amount of work each of them has to perform.
-          For example it can help a developer to decide whether he should
-          choose a per-cpu workqueue instead of a singlethreaded one.
-
 config BLK_DEV_IO_TRACE
 	bool "Support for tracing block IO actions"
 	depends on SYSFS

kernel/workqueue.c

@@ -33,41 +33,272 @@
 #include <linux/kallsyms.h>
 #include <linux/debug_locks.h>
 #include <linux/lockdep.h>
-#define CREATE_TRACE_POINTS
-#include <trace/events/workqueue.h>
+#include <linux/idr.h>
+
+#include "workqueue_sched.h"
+
+enum {
+	/* global_cwq flags */
+	GCWQ_MANAGE_WORKERS	= 1 << 0,	/* need to manage workers */
+	GCWQ_MANAGING_WORKERS	= 1 << 1,	/* managing workers */
+	GCWQ_DISASSOCIATED	= 1 << 2,	/* cpu can't serve workers */
+	GCWQ_FREEZING		= 1 << 3,	/* freeze in progress */
+	GCWQ_HIGHPRI_PENDING	= 1 << 4,	/* highpri works on queue */
+
+	/* worker flags */
+	WORKER_STARTED		= 1 << 0,	/* started */
+	WORKER_DIE		= 1 << 1,	/* die die die */
+	WORKER_IDLE		= 1 << 2,	/* is idle */
+	WORKER_PREP		= 1 << 3,	/* preparing to run works */
+	WORKER_ROGUE		= 1 << 4,	/* not bound to any cpu */
+	WORKER_REBIND		= 1 << 5,	/* mom is home, come back */
+	WORKER_CPU_INTENSIVE	= 1 << 6,	/* cpu intensive */
+	WORKER_UNBOUND		= 1 << 7,	/* worker is unbound */
+
+	WORKER_NOT_RUNNING	= WORKER_PREP | WORKER_ROGUE | WORKER_REBIND |
+				  WORKER_CPU_INTENSIVE | WORKER_UNBOUND,
+
+	/* gcwq->trustee_state */
+	TRUSTEE_START		= 0,		/* start */
+	TRUSTEE_IN_CHARGE	= 1,		/* trustee in charge of gcwq */
+	TRUSTEE_BUTCHER		= 2,		/* butcher workers */
+	TRUSTEE_RELEASE		= 3,		/* release workers */
+	TRUSTEE_DONE		= 4,		/* trustee is done */
+
+	BUSY_WORKER_HASH_ORDER	= 6,		/* 64 pointers */
+	BUSY_WORKER_HASH_SIZE	= 1 << BUSY_WORKER_HASH_ORDER,
+	BUSY_WORKER_HASH_MASK	= BUSY_WORKER_HASH_SIZE - 1,
+
+	MAX_IDLE_WORKERS_RATIO	= 4,		/* 1/4 of busy can be idle */
+	IDLE_WORKER_TIMEOUT	= 300 * HZ,	/* keep idle ones for 5 mins */
+
+	MAYDAY_INITIAL_TIMEOUT	= HZ / 100,	/* call for help after 10ms */
+	MAYDAY_INTERVAL		= HZ / 10,	/* and then every 100ms */
+	CREATE_COOLDOWN		= HZ,		/* time to breath after fail */
+	TRUSTEE_COOLDOWN	= HZ / 10,	/* for trustee draining */
+
+	/*
+	 * Rescue workers are used only on emergencies and shared by
+	 * all cpus.  Give -20.
+	 */
+	RESCUER_NICE_LEVEL	= -20,
+};
 
 /*
- * The per-CPU workqueue (if single thread, we always use the first
- * possible cpu).
+ * Structure fields follow one of the following exclusion rules.
+ *
+ * I: Set during initialization and read-only afterwards.
+ *
+ * P: Preemption protected.  Disabling preemption is enough and should
+ *    only be modified and accessed from the local cpu.
+ *
+ * L: gcwq->lock protected.  Access with gcwq->lock held.
+ *
+ * X: During normal operation, modification requires gcwq->lock and
+ *    should be done only from local cpu.  Either disabling preemption
+ *    on local cpu or grabbing gcwq->lock is enough for read access.
+ *    If GCWQ_DISASSOCIATED is set, it's identical to L.
+ *
+ * F: wq->flush_mutex protected.
+ *
+ * W: workqueue_lock protected.
  */
-struct cpu_workqueue_struct {
 
-	spinlock_t lock;
+struct global_cwq;
 
-	struct list_head worklist;
-	wait_queue_head_t more_work;
-	struct work_struct *current_work;
+/*
+ * The poor guys doing the actual heavy lifting.  All on-duty workers
+ * are either serving the manager role, on idle list or on busy hash.
+ */
+struct worker {
+	/* on idle list while idle, on busy hash table while busy */
+	union {
+		struct list_head	entry;	/* L: while idle */
+		struct hlist_node	hentry;	/* L: while busy */
+	};
 
-	struct workqueue_struct *wq;
-	struct task_struct *thread;
-} ____cacheline_aligned;
+	struct work_struct	*current_work;	/* L: work being processed */
+	struct cpu_workqueue_struct *current_cwq; /* L: current_work's cwq */
+	struct list_head	scheduled;	/* L: scheduled works */
+	struct task_struct	*task;		/* I: worker task */
+	struct global_cwq	*gcwq;		/* I: the associated gcwq */
+	/* 64 bytes boundary on 64bit, 32 on 32bit */
+	unsigned long		last_active;	/* L: last active timestamp */
+	unsigned int		flags;		/* X: flags */
+	int			id;		/* I: worker id */
+	struct work_struct	rebind_work;	/* L: rebind worker to cpu */
+};
+
+/*
+ * Global per-cpu workqueue.  There's one and only one for each cpu
+ * and all works are queued and processed here regardless of their
+ * target workqueues.
+ */
+struct global_cwq {
+	spinlock_t		lock;		/* the gcwq lock */
+	struct list_head	worklist;	/* L: list of pending works */
+	unsigned int		cpu;		/* I: the associated cpu */
+	unsigned int		flags;		/* L: GCWQ_* flags */
+
+	int			nr_workers;	/* L: total number of workers */
+	int			nr_idle;	/* L: currently idle ones */
+
+	/* workers are chained either in the idle_list or busy_hash */
+	struct list_head	idle_list;	/* X: list of idle workers */
+	struct hlist_head	busy_hash[BUSY_WORKER_HASH_SIZE];
+						/* L: hash of busy workers */
+
+	struct timer_list	idle_timer;	/* L: worker idle timeout */
+	struct timer_list	mayday_timer;	/* L: SOS timer for dworkers */
+
+	struct ida		worker_ida;	/* L: for worker IDs */
+
+	struct task_struct	*trustee;	/* L: for gcwq shutdown */
+	unsigned int		trustee_state;	/* L: trustee state */
+	wait_queue_head_t	trustee_wait;	/* trustee wait */
+	struct worker		*first_idle;	/* L: first idle worker */
+} ____cacheline_aligned_in_smp;
+
+/*
+ * The per-CPU workqueue.  The lower WORK_STRUCT_FLAG_BITS of
+ * work_struct->data are used for flags and thus cwqs need to be
+ * aligned at two's power of the number of flag bits.
+ */
+struct cpu_workqueue_struct {
+	struct global_cwq	*gcwq;		/* I: the associated gcwq */
+	struct workqueue_struct *wq;		/* I: the owning workqueue */
+	int			work_color;	/* L: current color */
+	int			flush_color;	/* L: flushing color */
+	int			nr_in_flight[WORK_NR_COLORS];
+						/* L: nr of in_flight works */
+	int			nr_active;	/* L: nr of active works */
+	int			max_active;	/* L: max active works */
+	struct list_head	delayed_works;	/* L: delayed works */
+};
+
+/*
+ * Structure used to wait for workqueue flush.
+ */
+struct wq_flusher {
+	struct list_head	list;		/* F: list of flushers */
+	int			flush_color;	/* F: flush color waiting for */
+	struct completion	done;		/* flush completion */
+};
+
+/*
+ * All cpumasks are assumed to be always set on UP and thus can't be
+ * used to determine whether there's something to be done.
+ */
+#ifdef CONFIG_SMP
+typedef cpumask_var_t mayday_mask_t;
+#define mayday_test_and_set_cpu(cpu, mask)	\
+	cpumask_test_and_set_cpu((cpu), (mask))
+#define mayday_clear_cpu(cpu, mask)		cpumask_clear_cpu((cpu), (mask))
+#define for_each_mayday_cpu(cpu, mask)		for_each_cpu((cpu), (mask))
+#define alloc_mayday_mask(maskp, gfp)		alloc_cpumask_var((maskp), (gfp))
+#define free_mayday_mask(mask)			free_cpumask_var((mask))
+#else
+typedef unsigned long mayday_mask_t;
+#define mayday_test_and_set_cpu(cpu, mask)	test_and_set_bit(0, &(mask))
+#define mayday_clear_cpu(cpu, mask)		clear_bit(0, &(mask))
+#define for_each_mayday_cpu(cpu, mask)		if ((cpu) = 0, (mask))
+#define alloc_mayday_mask(maskp, gfp)		true
+#define free_mayday_mask(mask)			do { } while (0)
+#endif
 
 /*
  * The externally visible workqueue abstraction is an array of
  * per-CPU workqueues:
  */
 struct workqueue_struct {
-	struct cpu_workqueue_struct *cpu_wq;
-	struct list_head list;
-	const char *name;
-	int singlethread;
-	int freezeable;		/* Freeze threads during suspend */
-	int rt;
+	unsigned int		flags;		/* I: WQ_* flags */
+	union {
+		struct cpu_workqueue_struct __percpu	*pcpu;
+		struct cpu_workqueue_struct		*single;
+		unsigned long				v;
+	} cpu_wq;				/* I: cwq's */
+	struct list_head	list;		/* W: list of all workqueues */
+
+	struct mutex		flush_mutex;	/* protects wq flushing */
+	int			work_color;	/* F: current work color */
+	int			flush_color;	/* F: current flush color */
+	atomic_t		nr_cwqs_to_flush; /* flush in progress */
+	struct wq_flusher	*first_flusher;	/* F: first flusher */
+	struct list_head	flusher_queue;	/* F: flush waiters */
+	struct list_head	flusher_overflow; /* F: flush overflow list */
+
+	mayday_mask_t		mayday_mask;	/* cpus requesting rescue */
+	struct worker		*rescuer;	/* I: rescue worker */
+
+	int			saved_max_active; /* W: saved cwq max_active */
+	const char		*name;		/* I: workqueue name */
 #ifdef CONFIG_LOCKDEP
-	struct lockdep_map lockdep_map;
+	struct lockdep_map	lockdep_map;
 #endif
 };
 
+struct workqueue_struct *system_wq __read_mostly;
+struct workqueue_struct *system_long_wq __read_mostly;
+struct workqueue_struct *system_nrt_wq __read_mostly;
+struct workqueue_struct *system_unbound_wq __read_mostly;
+EXPORT_SYMBOL_GPL(system_wq);
+EXPORT_SYMBOL_GPL(system_long_wq);
+EXPORT_SYMBOL_GPL(system_nrt_wq);
+EXPORT_SYMBOL_GPL(system_unbound_wq);
+
+#define for_each_busy_worker(worker, i, pos, gcwq)			\
+	for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++)			\
+		hlist_for_each_entry(worker, pos, &gcwq->busy_hash[i], hentry)
+
+static inline int __next_gcwq_cpu(int cpu, const struct cpumask *mask,
+				  unsigned int sw)
+{
+	if (cpu < nr_cpu_ids) {
+		if (sw & 1) {
+			cpu = cpumask_next(cpu, mask);
+			if (cpu < nr_cpu_ids)
+				return cpu;
+		}
+		if (sw & 2)
+			return WORK_CPU_UNBOUND;
+	}
+	return WORK_CPU_NONE;
+}
+
+static inline int __next_wq_cpu(int cpu, const struct cpumask *mask,
+				struct workqueue_struct *wq)
+{
+	return __next_gcwq_cpu(cpu, mask, !(wq->flags & WQ_UNBOUND) ? 1 : 2);
+}
+
+/*
+ * CPU iterators
+ *
+ * An extra gcwq is defined for an invalid cpu number
+ * (WORK_CPU_UNBOUND) to host workqueues which are not bound to any
+ * specific CPU.  The following iterators are similar to
+ * for_each_*_cpu() iterators but also considers the unbound gcwq.
+ *
+ * for_each_gcwq_cpu()		: possible CPUs + WORK_CPU_UNBOUND
+ * for_each_online_gcwq_cpu()	: online CPUs + WORK_CPU_UNBOUND
+ * for_each_cwq_cpu()		: possible CPUs for bound workqueues,
+ *				  WORK_CPU_UNBOUND for unbound workqueues
+ */
+#define for_each_gcwq_cpu(cpu)						\
+	for ((cpu) = __next_gcwq_cpu(-1, cpu_possible_mask, 3);		\
+	     (cpu) < WORK_CPU_NONE;					\
+	     (cpu) = __next_gcwq_cpu((cpu), cpu_possible_mask, 3))
+
+#define for_each_online_gcwq_cpu(cpu)					\
+	for ((cpu) = __next_gcwq_cpu(-1, cpu_online_mask, 3);		\
+	     (cpu) < WORK_CPU_NONE;					\
+	     (cpu) = __next_gcwq_cpu((cpu), cpu_online_mask, 3))
+
+#define for_each_cwq_cpu(cpu, wq)					\
+	for ((cpu) = __next_wq_cpu(-1, cpu_possible_mask, (wq));	\
+	     (cpu) < WORK_CPU_NONE;					\
+	     (cpu) = __next_wq_cpu((cpu), cpu_possible_mask, (wq)))
+
 #ifdef CONFIG_LOCKDEP
 /**
  * in_workqueue_context() - in context of specified workqueue?
@@ -122,7 +353,7 @@ static int work_fixup_activate(void *addr, enum debug_obj_state state)
 		 * statically initialized. We just make sure that it
 		 * is tracked in the object tracker.
 		 */
-		if (test_bit(WORK_STRUCT_STATIC, work_data_bits(work))) {
+		if (test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work))) {
 			debug_object_init(work, &work_debug_descr);
 			debug_object_activate(work, &work_debug_descr);
 			return 0;
@@ -196,94 +427,575 @@ static inline void debug_work_deactivate(struct work_struct *work) { }
 /* Serializes the accesses to the list of workqueues. */
 static DEFINE_SPINLOCK(workqueue_lock);
 static LIST_HEAD(workqueues);
+static bool workqueue_freezing;		/* W: have wqs started freezing? */
+
+/*
+ * The almighty global cpu workqueues.  nr_running is the only field
+ * which is expected to be used frequently by other cpus via
+ * try_to_wake_up().  Put it in a separate cacheline.
+ */
+static DEFINE_PER_CPU(struct global_cwq, global_cwq);
+static DEFINE_PER_CPU_SHARED_ALIGNED(atomic_t, gcwq_nr_running);
+
+/*
+ * Global cpu workqueue and nr_running counter for unbound gcwq.  The
+ * gcwq is always online, has GCWQ_DISASSOCIATED set, and all its
+ * workers have WORKER_UNBOUND set.
+ */
+static struct global_cwq unbound_global_cwq;
+static atomic_t unbound_gcwq_nr_running = ATOMIC_INIT(0);	/* always 0 */
+
+static int worker_thread(void *__worker);
+
+static struct global_cwq *get_gcwq(unsigned int cpu)
+{
+	if (cpu != WORK_CPU_UNBOUND)
+		return &per_cpu(global_cwq, cpu);
+	else
+		return &unbound_global_cwq;
+}
+
+static atomic_t *get_gcwq_nr_running(unsigned int cpu)
+{
+	if (cpu != WORK_CPU_UNBOUND)
+		return &per_cpu(gcwq_nr_running, cpu);
+	else
+		return &unbound_gcwq_nr_running;
+}
+
+static struct cpu_workqueue_struct *get_cwq(unsigned int cpu,
+					    struct workqueue_struct *wq)
+{
+	if (!(wq->flags & WQ_UNBOUND)) {
+		if (likely(cpu < nr_cpu_ids)) {
+#ifdef CONFIG_SMP
+			return per_cpu_ptr(wq->cpu_wq.pcpu, cpu);
+#else
+			return wq->cpu_wq.single;
+#endif
+		}
+	} else if (likely(cpu == WORK_CPU_UNBOUND))
+		return wq->cpu_wq.single;
+	return NULL;
+}
+
+static unsigned int work_color_to_flags(int color)
+{
+	return color << WORK_STRUCT_COLOR_SHIFT;
+}
+
+static int get_work_color(struct work_struct *work)
+{
+	return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) &
+		((1 << WORK_STRUCT_COLOR_BITS) - 1);
+}
+
+static int work_next_color(int color)
+{
+	return (color + 1) % WORK_NR_COLORS;
+}
 
-static int singlethread_cpu __read_mostly;
-static const struct cpumask *cpu_singlethread_map __read_mostly;
 /*
- * _cpu_down() first removes CPU from cpu_online_map, then CPU_DEAD
- * flushes cwq->worklist. This means that flush_workqueue/wait_on_work
- * which comes in between can't use for_each_online_cpu(). We could
- * use cpu_possible_map, the cpumask below is more a documentation
- * than optimization.
+ * A work's data points to the cwq with WORK_STRUCT_CWQ set while the
+ * work is on queue.  Once execution starts, WORK_STRUCT_CWQ is
+ * cleared and the work data contains the cpu number it was last on.
+ *
+ * set_work_{cwq|cpu}() and clear_work_data() can be used to set the
+ * cwq, cpu or clear work->data.  These functions should only be
+ * called while the work is owned - ie. while the PENDING bit is set.
+ *
+ * get_work_[g]cwq() can be used to obtain the gcwq or cwq
+ * corresponding to a work.  gcwq is available once the work has been
+ * queued anywhere after initialization.  cwq is available only from
+ * queueing until execution starts.
  */
-static cpumask_var_t cpu_populated_map __read_mostly;
+static inline void set_work_data(struct work_struct *work, unsigned long data,
+				 unsigned long flags)
+{
+	BUG_ON(!work_pending(work));
+	atomic_long_set(&work->data, data | flags | work_static(work));
+}
+
+static void set_work_cwq(struct work_struct *work,
+			 struct cpu_workqueue_struct *cwq,
+			 unsigned long extra_flags)
+{
+	set_work_data(work, (unsigned long)cwq,
+		      WORK_STRUCT_PENDING | WORK_STRUCT_CWQ | extra_flags);
+}
+
+static void set_work_cpu(struct work_struct *work, unsigned int cpu)
+{
+	set_work_data(work, cpu << WORK_STRUCT_FLAG_BITS, WORK_STRUCT_PENDING);
+}
 
-/* If it's single threaded, it isn't in the list of workqueues. */
-static inline int is_wq_single_threaded(struct workqueue_struct *wq)
+static void clear_work_data(struct work_struct *work)
 {
-	return wq->singlethread;
+	set_work_data(work, WORK_STRUCT_NO_CPU, 0);
 }
 
-static const struct cpumask *wq_cpu_map(struct workqueue_struct *wq)
+static struct cpu_workqueue_struct *get_work_cwq(struct work_struct *work)
 {
-	return is_wq_single_threaded(wq)
-		? cpu_singlethread_map : cpu_populated_map;
+	unsigned long data = atomic_long_read(&work->data);
+
+	if (data & WORK_STRUCT_CWQ)
+		return (void *)(data & WORK_STRUCT_WQ_DATA_MASK);
+	else
+		return NULL;
+}
+
+static struct global_cwq *get_work_gcwq(struct work_struct *work)
+{
+	unsigned long data = atomic_long_read(&work->data);
+	unsigned int cpu;
+
+	if (data & WORK_STRUCT_CWQ)
+		return ((struct cpu_workqueue_struct *)
+			(data & WORK_STRUCT_WQ_DATA_MASK))->gcwq;
+
+	cpu = data >> WORK_STRUCT_FLAG_BITS;
+	if (cpu == WORK_CPU_NONE)
+		return NULL;
+
+	BUG_ON(cpu >= nr_cpu_ids && cpu != WORK_CPU_UNBOUND);
+	return get_gcwq(cpu);
 }
 
-static
-struct cpu_workqueue_struct *wq_per_cpu(struct workqueue_struct *wq, int cpu)
+/*
+ * Policy functions.  These define the policies on how the global
+ * worker pool is managed.  Unless noted otherwise, these functions
+ * assume that they're being called with gcwq->lock held.
+ */
+
+static bool __need_more_worker(struct global_cwq *gcwq)
 {
-	if (unlikely(is_wq_single_threaded(wq)))
-		cpu = singlethread_cpu;
-	return per_cpu_ptr(wq->cpu_wq, cpu);
+	return !atomic_read(get_gcwq_nr_running(gcwq->cpu)) ||
+		gcwq->flags & GCWQ_HIGHPRI_PENDING;
 }
 
 /*
- * Set the workqueue on which a work item is to be run
- * - Must *only* be called if the pending flag is set
+ * Need to wake up a worker?  Called from anything but currently
+ * running workers.
  */
-static inline void set_wq_data(struct work_struct *work,
-				struct cpu_workqueue_struct *cwq)
+static bool need_more_worker(struct global_cwq *gcwq)
 {
-	unsigned long new;
+	return !list_empty(&gcwq->worklist) && __need_more_worker(gcwq);
+}
 
-	BUG_ON(!work_pending(work));
+/* Can I start working?  Called from busy but !running workers. */
+static bool may_start_working(struct global_cwq *gcwq)
+{
+	return gcwq->nr_idle;
+}
+
+/* Do I need to keep working?  Called from currently running workers. */
+static bool keep_working(struct global_cwq *gcwq)
+{
+	atomic_t *nr_running = get_gcwq_nr_running(gcwq->cpu);
+
+	return !list_empty(&gcwq->worklist) && atomic_read(nr_running) <= 1;
+}
+
+/* Do we need a new worker?  Called from manager. */
+static bool need_to_create_worker(struct global_cwq *gcwq)
+{
+	return need_more_worker(gcwq) && !may_start_working(gcwq);
+}
 
-	new = (unsigned long) cwq | (1UL << WORK_STRUCT_PENDING);
-	new |= WORK_STRUCT_FLAG_MASK & *work_data_bits(work);
-	atomic_long_set(&work->data, new);
+/* Do I need to be the manager? */
+static bool need_to_manage_workers(struct global_cwq *gcwq)
+{
+	return need_to_create_worker(gcwq) || gcwq->flags & GCWQ_MANAGE_WORKERS;
+}
+
+/* Do we have too many workers and should some go away? */
+static bool too_many_workers(struct global_cwq *gcwq)
+{
+	bool managing = gcwq->flags & GCWQ_MANAGING_WORKERS;
+	int nr_idle = gcwq->nr_idle + managing; /* manager is considered idle */
+	int nr_busy = gcwq->nr_workers - nr_idle;
+
+	return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy;
 }
 
 /*
- * Clear WORK_STRUCT_PENDING and the workqueue on which it was queued.
+ * Wake up functions.
+ */
+
+/* Return the first worker.  Safe with preemption disabled */
+static struct worker *first_worker(struct global_cwq *gcwq)
+{
+	if (unlikely(list_empty(&gcwq->idle_list)))
+		return NULL;
+
+	return list_first_entry(&gcwq->idle_list, struct worker, entry);
+}
+
+/**
+ * wake_up_worker - wake up an idle worker
+ * @gcwq: gcwq to wake worker for
+ *
+ * Wake up the first idle worker of @gcwq.
+ *
+ * CONTEXT:
+ * spin_lock_irq(gcwq->lock).
+ */
+static void wake_up_worker(struct global_cwq *gcwq)
+{
+	struct worker *worker = first_worker(gcwq);
+
+	if (likely(worker))
+		wake_up_process(worker->task);
+}
+
+/**
+ * wq_worker_waking_up - a worker is waking up
+ * @task: task waking up
+ * @cpu: CPU @task is waking up to
+ *
+ * This function is called during try_to_wake_up() when a worker is
+ * being awoken.
+ *
+ * CONTEXT:
+ * spin_lock_irq(rq->lock)
+ */
+void wq_worker_waking_up(struct task_struct *task, unsigned int cpu)
+{
+	struct worker *worker = kthread_data(task);
+
+	if (likely(!(worker->flags & WORKER_NOT_RUNNING)))
+		atomic_inc(get_gcwq_nr_running(cpu));
+}
+
+/**
+ * wq_worker_sleeping - a worker is going to sleep
+ * @task: task going to sleep
+ * @cpu: CPU in question, must be the current CPU number
+ *
+ * This function is called during schedule() when a busy worker is
+ * going to sleep.  Worker on the same cpu can be woken up by
+ * returning pointer to its task.
+ *
+ * CONTEXT:
+ * spin_lock_irq(rq->lock)
+ *
+ * RETURNS:
+ * Worker task on @cpu to wake up, %NULL if none.
+ */
+struct task_struct *wq_worker_sleeping(struct task_struct *task,
+				       unsigned int cpu)
+{
+	struct worker *worker = kthread_data(task), *to_wakeup = NULL;
+	struct global_cwq *gcwq = get_gcwq(cpu);
+	atomic_t *nr_running = get_gcwq_nr_running(cpu);
+
+	if (unlikely(worker->flags & WORKER_NOT_RUNNING))
+		return NULL;
+
+	/* this can only happen on the local cpu */
+	BUG_ON(cpu != raw_smp_processor_id());
+
+	/*
+	 * The counterpart of the following dec_and_test, implied mb,
+	 * worklist not empty test sequence is in insert_work().
+	 * Please read comment there.
+	 *
+	 * NOT_RUNNING is clear.  This means that trustee is not in
+	 * charge and we're running on the local cpu w/ rq lock held
+	 * and preemption disabled, which in turn means that none else
+	 * could be manipulating idle_list, so dereferencing idle_list
+	 * without gcwq lock is safe.
+	 */
+	if (atomic_dec_and_test(nr_running) && !list_empty(&gcwq->worklist))
+		to_wakeup = first_worker(gcwq);
+	return to_wakeup ? to_wakeup->task : NULL;
+}
+
+/**
+ * worker_set_flags - set worker flags and adjust nr_running accordingly
+ * @worker: self
+ * @flags: flags to set
+ * @wakeup: wakeup an idle worker if necessary
+ *
+ * Set @flags in @worker->flags and adjust nr_running accordingly.  If
+ * nr_running becomes zero and @wakeup is %true, an idle worker is
+ * woken up.
+ *
+ * CONTEXT:
+ * spin_lock_irq(gcwq->lock)
+ */
+static inline void worker_set_flags(struct worker *worker, unsigned int flags,
+				    bool wakeup)
+{
+	struct global_cwq *gcwq = worker->gcwq;
+
+	WARN_ON_ONCE(worker->task != current);
+
+	/*
+	 * If transitioning into NOT_RUNNING, adjust nr_running and
+	 * wake up an idle worker as necessary if requested by
+	 * @wakeup.
+	 */
+	if ((flags & WORKER_NOT_RUNNING) &&
+	    !(worker->flags & WORKER_NOT_RUNNING)) {
+		atomic_t *nr_running = get_gcwq_nr_running(gcwq->cpu);
+
+		if (wakeup) {
+			if (atomic_dec_and_test(nr_running) &&
+			    !list_empty(&gcwq->worklist))
+				wake_up_worker(gcwq);
+		} else
+			atomic_dec(nr_running);
+	}
+
+	worker->flags |= flags;
+}
+
+/**
+ * worker_clr_flags - clear worker flags and adjust nr_running accordingly
+ * @worker: self
+ * @flags: flags to clear
+ *
+ * Clear @flags in @worker->flags and adjust nr_running accordingly.
+ *
+ * CONTEXT:
+ * spin_lock_irq(gcwq->lock)
+ */
+static inline void worker_clr_flags(struct worker *worker, unsigned int flags)
+{
+	struct global_cwq *gcwq = worker->gcwq;
+	unsigned int oflags = worker->flags;
+
+	WARN_ON_ONCE(worker->task != current);
+
+	worker->flags &= ~flags;
+
+	/* if transitioning out of NOT_RUNNING, increment nr_running */
+	if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING))
+		if (!(worker->flags & WORKER_NOT_RUNNING))
+			atomic_inc(get_gcwq_nr_running(gcwq->cpu));
+}
+
+/**
+ * busy_worker_head - return the busy hash head for a work
+ * @gcwq: gcwq of interest
+ * @work: work to be hashed
+ *
+ * Return hash head of @gcwq for @work.
+ *
+ * CONTEXT:
+ * spin_lock_irq(gcwq->lock).
+ *
+ * RETURNS:
+ * Pointer to the hash head.
+ */
+static struct hlist_head *busy_worker_head(struct global_cwq *gcwq,
+					   struct work_struct *work)
+{
+	const int base_shift = ilog2(sizeof(struct work_struct));
+	unsigned long v = (unsigned long)work;
+
+	/* simple shift and fold hash, do we need something better? */
+	v >>= base_shift;
+	v += v >> BUSY_WORKER_HASH_ORDER;
+	v &= BUSY_WORKER_HASH_MASK;
+
+	return &gcwq->busy_hash[v];
+}
+
+/**
+ * __find_worker_executing_work - find worker which is executing a work
+ * @gcwq: gcwq of interest
+ * @bwh: hash head as returned by busy_worker_head()
+ * @work: work to find worker for
+ *
+ * Find a worker which is executing @work on @gcwq.  @bwh should be
+ * the hash head obtained by calling busy_worker_head() with the same
+ * work.
+ *
+ * CONTEXT:
+ * spin_lock_irq(gcwq->lock).
+ *
+ * RETURNS:
+ * Pointer to worker which is executing @work if found, NULL
+ * otherwise.
+ */
+static struct worker *__find_worker_executing_work(struct global_cwq *gcwq,
+						   struct hlist_head *bwh,
+						   struct work_struct *work)
+{
+	struct worker *worker;
+	struct hlist_node *tmp;
+
+	hlist_for_each_entry(worker, tmp, bwh, hentry)
+		if (worker->current_work == work)
+			return worker;
+	return NULL;
+}
+
+/**
+ * find_worker_executing_work - find worker which is executing a work
+ * @gcwq: gcwq of interest
+ * @work: work to find worker for
+ *
+ * Find a worker which is executing @work on @gcwq.  This function is
+ * identical to __find_worker_executing_work() except that this
+ * function calculates @bwh itself.
+ *
+ * CONTEXT:
+ * spin_lock_irq(gcwq->lock).
+ *
+ * RETURNS:
+ * Pointer to worker which is executing @work if found, NULL
+ * otherwise.
  */
-static inline void clear_wq_data(struct work_struct *work)
+static struct worker *find_worker_executing_work(struct global_cwq *gcwq,
+						 struct work_struct *work)
 {
-	unsigned long flags = *work_data_bits(work) &
-				(1UL << WORK_STRUCT_STATIC);
-	atomic_long_set(&work->data, flags);
+	return __find_worker_executing_work(gcwq, busy_worker_head(gcwq, work),
+					    work);
 }
 
-static inline
-struct cpu_workqueue_struct *get_wq_data(struct work_struct *work)
+/**
+ * gcwq_determine_ins_pos - find insertion position
+ * @gcwq: gcwq of interest
+ * @cwq: cwq a work is being queued for
+ *
+ * A work for @cwq is about to be queued on @gcwq, determine insertion
+ * position for the work.  If @cwq is for HIGHPRI wq, the work is
+ * queued at the head of the queue but in FIFO order with respect to
+ * other HIGHPRI works; otherwise, at the end of the queue.  This
+ * function also sets GCWQ_HIGHPRI_PENDING flag to hint @gcwq that
+ * there are HIGHPRI works pending.
+ *
+ * CONTEXT:
+ * spin_lock_irq(gcwq->lock).
+ *
+ * RETURNS:
+ * Pointer to inserstion position.
+ */
+static inline struct list_head *gcwq_determine_ins_pos(struct global_cwq *gcwq,
+					       struct cpu_workqueue_struct *cwq)
 {
-	return (void *) (atomic_long_read(&work->data) & WORK_STRUCT_WQ_DATA_MASK);
+	struct work_struct *twork;
+
+	if (likely(!(cwq->wq->flags & WQ_HIGHPRI)))
+		return &gcwq->worklist;
+
+	list_for_each_entry(twork, &gcwq->worklist, entry) {
+		struct cpu_workqueue_struct *tcwq = get_work_cwq(twork);
+
+		if (!(tcwq->wq->flags & WQ_HIGHPRI))
+			break;
+	}
+
+	gcwq->flags |= GCWQ_HIGHPRI_PENDING;
+	return &twork->entry;
 }
 
+/**
+ * insert_work - insert a work into gcwq
+ * @cwq: cwq @work belongs to
+ * @work: work to insert
+ * @head: insertion point
+ * @extra_flags: extra WORK_STRUCT_* flags to set
+ *
+ * Insert @work which belongs to @cwq into @gcwq after @head.
+ * @extra_flags is or'd to work_struct flags.
+ *
+ * CONTEXT:
+ * spin_lock_irq(gcwq->lock).
+ */
 static void insert_work(struct cpu_workqueue_struct *cwq,
-			struct work_struct *work, struct list_head *head)
+			struct work_struct *work, struct list_head *head,
+			unsigned int extra_flags)
 {
-	trace_workqueue_insertion(cwq->thread, work);
+	struct global_cwq *gcwq = cwq->gcwq;
+
+	/* we own @work, set data and link */
+	set_work_cwq(work, cwq, extra_flags);
 
-	set_wq_data(work, cwq);
 	/*
 	 * Ensure that we get the right work->data if we see the
 	 * result of list_add() below, see try_to_grab_pending().
 	 */
 	smp_wmb();
+
 	list_add_tail(&work->entry, head);
-	wake_up(&cwq->more_work);
+
+	/*
+	 * Ensure either worker_sched_deactivated() sees the above
+	 * list_add_tail() or we see zero nr_running to avoid workers
+	 * lying around lazily while there are works to be processed.
+	 */
+	smp_mb();
+
+	if (__need_more_worker(gcwq))
+		wake_up_worker(gcwq);
 }
 
-static void __queue_work(struct cpu_workqueue_struct *cwq,
+static void __queue_work(unsigned int cpu, struct workqueue_struct *wq,
 			 struct work_struct *work)
 {
+	struct global_cwq *gcwq;
+	struct cpu_workqueue_struct *cwq;
+	struct list_head *worklist;
 	unsigned long flags;
 
 	debug_work_activate(work);
-	spin_lock_irqsave(&cwq->lock, flags);
-	insert_work(cwq, work, &cwq->worklist);
-	spin_unlock_irqrestore(&cwq->lock, flags);
+
+	/* determine gcwq to use */
+	if (!(wq->flags & WQ_UNBOUND)) {
+		struct global_cwq *last_gcwq;
+
+		if (unlikely(cpu == WORK_CPU_UNBOUND))
+			cpu = raw_smp_processor_id();
+
+		/*
+		 * It's multi cpu.  If @wq is non-reentrant and @work
+		 * was previously on a different cpu, it might still
+		 * be running there, in which case the work needs to
+		 * be queued on that cpu to guarantee non-reentrance.
+		 */
+		gcwq = get_gcwq(cpu);
+		if (wq->flags & WQ_NON_REENTRANT &&
+		    (last_gcwq = get_work_gcwq(work)) && last_gcwq != gcwq) {
+			struct worker *worker;
+
+			spin_lock_irqsave(&last_gcwq->lock, flags);
+
+			worker = find_worker_executing_work(last_gcwq, work);
+
+			if (worker && worker->current_cwq->wq == wq)
+				gcwq = last_gcwq;
+			else {
+				/* meh... not running there, queue here */
+				spin_unlock_irqrestore(&last_gcwq->lock, flags);
+				spin_lock_irqsave(&gcwq->lock, flags);
+			}
+		} else
+			spin_lock_irqsave(&gcwq->lock, flags);
+	} else {
+		gcwq = get_gcwq(WORK_CPU_UNBOUND);
+		spin_lock_irqsave(&gcwq->lock, flags);
+	}
+
+	/* gcwq determined, get cwq and queue */
+	cwq = get_cwq(gcwq->cpu, wq);
+
+	BUG_ON(!list_empty(&work->entry));
+
+	cwq->nr_in_flight[cwq->work_color]++;
+
+	if (likely(cwq->nr_active < cwq->max_active)) {
+		cwq->nr_active++;
+		worklist = gcwq_determine_ins_pos(gcwq, cwq);
+	} else
+		worklist = &cwq->delayed_works;
+
+	insert_work(cwq, work, worklist, work_color_to_flags(cwq->work_color));
+
+	spin_unlock_irqrestore(&gcwq->lock, flags);
 }
 
 /**
@@ -323,9 +1035,8 @@ queue_work_on(int cpu, struct workqueue_struct *wq, struct work_struct *work)
 {
 	int ret = 0;
 
-	if (!test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(work))) {
-		BUG_ON(!list_empty(&work->entry));
-		__queue_work(wq_per_cpu(wq, cpu), work);
+	if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
+		__queue_work(cpu, wq, work);
 		ret = 1;
 	}
 	return ret;
@@ -335,10 +1046,9 @@ EXPORT_SYMBOL_GPL(queue_work_on);
 static void delayed_work_timer_fn(unsigned long __data)
 {
 	struct delayed_work *dwork = (struct delayed_work *)__data;
-	struct cpu_workqueue_struct *cwq = get_wq_data(&dwork->work);
-	struct workqueue_struct *wq = cwq->wq;
+	struct cpu_workqueue_struct *cwq = get_work_cwq(&dwork->work);
 
-	__queue_work(wq_per_cpu(wq, smp_processor_id()), &dwork->work);
+	__queue_work(smp_processor_id(), cwq->wq, &dwork->work);
 }
 
 /**
@@ -375,14 +1085,31 @@ int queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
 	struct timer_list *timer = &dwork->timer;
 	struct work_struct *work = &dwork->work;
 
-	if (!test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(work))) {
+	if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
+		unsigned int lcpu;
+
 		BUG_ON(timer_pending(timer));
 		BUG_ON(!list_empty(&work->entry));
 
 		timer_stats_timer_set_start_info(&dwork->timer);
 
-		/* This stores cwq for the moment, for the timer_fn */
-		set_wq_data(work, wq_per_cpu(wq, raw_smp_processor_id()));
+		/*
+		 * This stores cwq for the moment, for the timer_fn.
+		 * Note that the work's gcwq is preserved to allow
+		 * reentrance detection for delayed works.
+		 */
+		if (!(wq->flags & WQ_UNBOUND)) {
+			struct global_cwq *gcwq = get_work_gcwq(work);
+
+			if (gcwq && gcwq->cpu != WORK_CPU_UNBOUND)
+				lcpu = gcwq->cpu;
+			else
+				lcpu = raw_smp_processor_id();
+		} else
+			lcpu = WORK_CPU_UNBOUND;
+
+		set_work_cwq(work, get_cwq(lcpu, wq), 0);
+
 		timer->expires = jiffies + delay;
 		timer->data = (unsigned long)dwork;
 		timer->function = delayed_work_timer_fn;
@@ -397,80 +1124,872 @@ int queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
 }
 EXPORT_SYMBOL_GPL(queue_delayed_work_on);
 
-static void run_workqueue(struct cpu_workqueue_struct *cwq)
+/**
+ * worker_enter_idle - enter idle state
+ * @worker: worker which is entering idle state
+ *
+ * @worker is entering idle state.  Update stats and idle timer if
+ * necessary.
+ *
+ * LOCKING:
+ * spin_lock_irq(gcwq->lock).
+ */
+static void worker_enter_idle(struct worker *worker)
 {
-	spin_lock_irq(&cwq->lock);
-	while (!list_empty(&cwq->worklist)) {
-		struct work_struct *work = list_entry(cwq->worklist.next,
-						struct work_struct, entry);
-		work_func_t f = work->func;
-#ifdef CONFIG_LOCKDEP
+	struct global_cwq *gcwq = worker->gcwq;
+
+	BUG_ON(worker->flags & WORKER_IDLE);
+	BUG_ON(!list_empty(&worker->entry) &&
+	       (worker->hentry.next || worker->hentry.pprev));
+
+	/* can't use worker_set_flags(), also called from start_worker() */
+	worker->flags |= WORKER_IDLE;
+	gcwq->nr_idle++;
+	worker->last_active = jiffies;
+
+	/* idle_list is LIFO */
+	list_add(&worker->entry, &gcwq->idle_list);
+
+	if (likely(!(worker->flags & WORKER_ROGUE))) {
+		if (too_many_workers(gcwq) && !timer_pending(&gcwq->idle_timer))
+			mod_timer(&gcwq->idle_timer,
+				  jiffies + IDLE_WORKER_TIMEOUT);
+	} else
+		wake_up_all(&gcwq->trustee_wait);
+
+	/* sanity check nr_running */
+	WARN_ON_ONCE(gcwq->nr_workers == gcwq->nr_idle &&
+		     atomic_read(get_gcwq_nr_running(gcwq->cpu)));
+}
+
+/**
+ * worker_leave_idle - leave idle state
+ * @worker: worker which is leaving idle state
+ *
+ * @worker is leaving idle state.  Update stats.
+ *
+ * LOCKING:
+ * spin_lock_irq(gcwq->lock).
+ */
+static void worker_leave_idle(struct worker *worker)
+{
+	struct global_cwq *gcwq = worker->gcwq;
+
+	BUG_ON(!(worker->flags & WORKER_IDLE));
+	worker_clr_flags(worker, WORKER_IDLE);
+	gcwq->nr_idle--;
+	list_del_init(&worker->entry);
+}
+
+/**
+ * worker_maybe_bind_and_lock - bind worker to its cpu if possible and lock gcwq
+ * @worker: self
+ *
+ * Works which are scheduled while the cpu is online must at least be
+ * scheduled to a worker which is bound to the cpu so that if they are
+ * flushed from cpu callbacks while cpu is going down, they are
+ * guaranteed to execute on the cpu.
+ *
+ * This function is to be used by rogue workers and rescuers to bind
+ * themselves to the target cpu and may race with cpu going down or
+ * coming online.  kthread_bind() can't be used because it may put the
+ * worker to already dead cpu and set_cpus_allowed_ptr() can't be used
+ * verbatim as it's best effort and blocking and gcwq may be
+ * [dis]associated in the meantime.
+ *
+ * This function tries set_cpus_allowed() and locks gcwq and verifies
+ * the binding against GCWQ_DISASSOCIATED which is set during
+ * CPU_DYING and cleared during CPU_ONLINE, so if the worker enters
+ * idle state or fetches works without dropping lock, it can guarantee
+ * the scheduling requirement described in the first paragraph.
+ *
+ * CONTEXT:
+ * Might sleep.  Called without any lock but returns with gcwq->lock
+ * held.
+ *
+ * RETURNS:
+ * %true if the associated gcwq is online (@worker is successfully
+ * bound), %false if offline.
+ */
+static bool worker_maybe_bind_and_lock(struct worker *worker)
+{
+	struct global_cwq *gcwq = worker->gcwq;
+	struct task_struct *task = worker->task;
+
+	while (true) {
 		/*
-		 * It is permissible to free the struct work_struct
-		 * from inside the function that is called from it,
-		 * this we need to take into account for lockdep too.
-		 * To avoid bogus "held lock freed" warnings as well
-		 * as problems when looking into work->lockdep_map,
-		 * make a copy and use that here.
+		 * The following call may fail, succeed or succeed
+		 * without actually migrating the task to the cpu if
+		 * it races with cpu hotunplug operation.  Verify
+		 * against GCWQ_DISASSOCIATED.
 		 */
-		struct lockdep_map lockdep_map = work->lockdep_map;
-#endif
-		trace_workqueue_execution(cwq->thread, work);
-		debug_work_deactivate(work);
-		cwq->current_work = work;
-		list_del_init(cwq->worklist.next);
-		spin_unlock_irq(&cwq->lock);
-
-		BUG_ON(get_wq_data(work) != cwq);
-		work_clear_pending(work);
-		lock_map_acquire(&cwq->wq->lockdep_map);
-		lock_map_acquire(&lockdep_map);
-		f(work);
-		lock_map_release(&lockdep_map);
-		lock_map_release(&cwq->wq->lockdep_map);
-
-		if (unlikely(in_atomic() || lockdep_depth(current) > 0)) {
-			printk(KERN_ERR "BUG: workqueue leaked lock or atomic: "
-					"%s/0x%08x/%d\n",
-					current->comm, preempt_count(),
-				       	task_pid_nr(current));
-			printk(KERN_ERR "    last function: ");
-			print_symbol("%s\n", (unsigned long)f);
-			debug_show_held_locks(current);
-			dump_stack();
+		if (!(gcwq->flags & GCWQ_DISASSOCIATED))
+			set_cpus_allowed_ptr(task, get_cpu_mask(gcwq->cpu));
+
+		spin_lock_irq(&gcwq->lock);
+		if (gcwq->flags & GCWQ_DISASSOCIATED)
+			return false;
+		if (task_cpu(task) == gcwq->cpu &&
+		    cpumask_equal(&current->cpus_allowed,
+				  get_cpu_mask(gcwq->cpu)))
+			return true;
+		spin_unlock_irq(&gcwq->lock);
+
+		/* CPU has come up inbetween, retry migration */
+		cpu_relax();
+	}
+}
+
+/*
+ * Function for worker->rebind_work used to rebind rogue busy workers
+ * to the associated cpu which is coming back online.  This is
+ * scheduled by cpu up but can race with other cpu hotplug operations
+ * and may be executed twice without intervening cpu down.
+ */
+static void worker_rebind_fn(struct work_struct *work)
+{
+	struct worker *worker = container_of(work, struct worker, rebind_work);
+	struct global_cwq *gcwq = worker->gcwq;
+
+	if (worker_maybe_bind_and_lock(worker))
+		worker_clr_flags(worker, WORKER_REBIND);
+
+	spin_unlock_irq(&gcwq->lock);
+}
+
+static struct worker *alloc_worker(void)
+{
+	struct worker *worker;
+
+	worker = kzalloc(sizeof(*worker), GFP_KERNEL);
+	if (worker) {
+		INIT_LIST_HEAD(&worker->entry);
+		INIT_LIST_HEAD(&worker->scheduled);
+		INIT_WORK(&worker->rebind_work, worker_rebind_fn);
+		/* on creation a worker is in !idle && prep state */
+		worker->flags = WORKER_PREP;
+	}
+	return worker;
+}
+
+/**
+ * create_worker - create a new workqueue worker
+ * @gcwq: gcwq the new worker will belong to
+ * @bind: whether to set affinity to @cpu or not
+ *
+ * Create a new worker which is bound to @gcwq.  The returned worker
+ * can be started by calling start_worker() or destroyed using
+ * destroy_worker().
+ *
+ * CONTEXT:
+ * Might sleep.  Does GFP_KERNEL allocations.
+ *
+ * RETURNS:
+ * Pointer to the newly created worker.
+ */
+static struct worker *create_worker(struct global_cwq *gcwq, bool bind)
+{
+	bool on_unbound_cpu = gcwq->cpu == WORK_CPU_UNBOUND;
+	struct worker *worker = NULL;
+	int id = -1;
+
+	spin_lock_irq(&gcwq->lock);
+	while (ida_get_new(&gcwq->worker_ida, &id)) {
+		spin_unlock_irq(&gcwq->lock);
+		if (!ida_pre_get(&gcwq->worker_ida, GFP_KERNEL))
+			goto fail;
+		spin_lock_irq(&gcwq->lock);
+	}
+	spin_unlock_irq(&gcwq->lock);
+
+	worker = alloc_worker();
+	if (!worker)
+		goto fail;
+
+	worker->gcwq = gcwq;
+	worker->id = id;
+
+	if (!on_unbound_cpu)
+		worker->task = kthread_create(worker_thread, worker,
+					      "kworker/%u:%d", gcwq->cpu, id);
+	else
+		worker->task = kthread_create(worker_thread, worker,
+					      "kworker/u:%d", id);
+	if (IS_ERR(worker->task))
+		goto fail;
+
+	/*
+	 * A rogue worker will become a regular one if CPU comes
+	 * online later on.  Make sure every worker has
+	 * PF_THREAD_BOUND set.
+	 */
+	if (bind && !on_unbound_cpu)
+		kthread_bind(worker->task, gcwq->cpu);
+	else {
+		worker->task->flags |= PF_THREAD_BOUND;
+		if (on_unbound_cpu)
+			worker->flags |= WORKER_UNBOUND;
+	}
+
+	return worker;
+fail:
+	if (id >= 0) {
+		spin_lock_irq(&gcwq->lock);
+		ida_remove(&gcwq->worker_ida, id);
+		spin_unlock_irq(&gcwq->lock);
+	}
+	kfree(worker);
+	return NULL;
+}
+
+/**
+ * start_worker - start a newly created worker
+ * @worker: worker to start
+ *
+ * Make the gcwq aware of @worker and start it.
+ *
+ * CONTEXT:
+ * spin_lock_irq(gcwq->lock).
+ */
+static void start_worker(struct worker *worker)
+{
+	worker->flags |= WORKER_STARTED;
+	worker->gcwq->nr_workers++;
+	worker_enter_idle(worker);
+	wake_up_process(worker->task);
+}
+
+/**
+ * destroy_worker - destroy a workqueue worker
+ * @worker: worker to be destroyed
+ *
+ * Destroy @worker and adjust @gcwq stats accordingly.
+ *
+ * CONTEXT:
+ * spin_lock_irq(gcwq->lock) which is released and regrabbed.
+ */
+static void destroy_worker(struct worker *worker)
+{
+	struct global_cwq *gcwq = worker->gcwq;
+	int id = worker->id;
+
+	/* sanity check frenzy */
+	BUG_ON(worker->current_work);
+	BUG_ON(!list_empty(&worker->scheduled));
+
+	if (worker->flags & WORKER_STARTED)
+		gcwq->nr_workers--;
+	if (worker->flags & WORKER_IDLE)
+		gcwq->nr_idle--;
+
+	list_del_init(&worker->entry);
+	worker->flags |= WORKER_DIE;
+
+	spin_unlock_irq(&gcwq->lock);
+
+	kthread_stop(worker->task);
+	kfree(worker);
+
+	spin_lock_irq(&gcwq->lock);
+	ida_remove(&gcwq->worker_ida, id);
+}
+
+static void idle_worker_timeout(unsigned long __gcwq)
+{
+	struct global_cwq *gcwq = (void *)__gcwq;
+
+	spin_lock_irq(&gcwq->lock);
+
+	if (too_many_workers(gcwq)) {
+		struct worker *worker;
+		unsigned long expires;
+
+		/* idle_list is kept in LIFO order, check the last one */
+		worker = list_entry(gcwq->idle_list.prev, struct worker, entry);
+		expires = worker->last_active + IDLE_WORKER_TIMEOUT;
+
+		if (time_before(jiffies, expires))
+			mod_timer(&gcwq->idle_timer, expires);
+		else {
+			/* it's been idle for too long, wake up manager */
+			gcwq->flags |= GCWQ_MANAGE_WORKERS;
+			wake_up_worker(gcwq);
 		}
+	}
+
+	spin_unlock_irq(&gcwq->lock);
+}
 
-		spin_lock_irq(&cwq->lock);
-		cwq->current_work = NULL;
+static bool send_mayday(struct work_struct *work)
+{
+	struct cpu_workqueue_struct *cwq = get_work_cwq(work);
+	struct workqueue_struct *wq = cwq->wq;
+	unsigned int cpu;
+
+	if (!(wq->flags & WQ_RESCUER))
+		return false;
+
+	/* mayday mayday mayday */
+	cpu = cwq->gcwq->cpu;
+	/* WORK_CPU_UNBOUND can't be set in cpumask, use cpu 0 instead */
+	if (cpu == WORK_CPU_UNBOUND)
+		cpu = 0;
+	if (!mayday_test_and_set_cpu(cpu, wq->mayday_mask))
+		wake_up_process(wq->rescuer->task);
+	return true;
+}
+
+static void gcwq_mayday_timeout(unsigned long __gcwq)
+{
+	struct global_cwq *gcwq = (void *)__gcwq;
+	struct work_struct *work;
+
+	spin_lock_irq(&gcwq->lock);
+
+	if (need_to_create_worker(gcwq)) {
+		/*
+		 * We've been trying to create a new worker but
+		 * haven't been successful.  We might be hitting an
+		 * allocation deadlock.  Send distress signals to
+		 * rescuers.
+		 */
+		list_for_each_entry(work, &gcwq->worklist, entry)
+			send_mayday(work);
 	}
-	spin_unlock_irq(&cwq->lock);
+
+	spin_unlock_irq(&gcwq->lock);
+
+	mod_timer(&gcwq->mayday_timer, jiffies + MAYDAY_INTERVAL);
 }
 
-static int worker_thread(void *__cwq)
+/**
+ * maybe_create_worker - create a new worker if necessary
+ * @gcwq: gcwq to create a new worker for
+ *
+ * Create a new worker for @gcwq if necessary.  @gcwq is guaranteed to
+ * have at least one idle worker on return from this function.  If
+ * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is
+ * sent to all rescuers with works scheduled on @gcwq to resolve
+ * possible allocation deadlock.
+ *
+ * On return, need_to_create_worker() is guaranteed to be false and
+ * may_start_working() true.
+ *
+ * LOCKING:
+ * spin_lock_irq(gcwq->lock) which may be released and regrabbed
+ * multiple times.  Does GFP_KERNEL allocations.  Called only from
+ * manager.
+ *
+ * RETURNS:
+ * false if no action was taken and gcwq->lock stayed locked, true
+ * otherwise.
+ */
+static bool maybe_create_worker(struct global_cwq *gcwq)
 {
-	struct cpu_workqueue_struct *cwq = __cwq;
-	DEFINE_WAIT(wait);
+	if (!need_to_create_worker(gcwq))
+		return false;
+restart:
+	spin_unlock_irq(&gcwq->lock);
+
+	/* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */
+	mod_timer(&gcwq->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT);
+
+	while (true) {
+		struct worker *worker;
+
+		worker = create_worker(gcwq, true);
+		if (worker) {
+			del_timer_sync(&gcwq->mayday_timer);
+			spin_lock_irq(&gcwq->lock);
+			start_worker(worker);
+			BUG_ON(need_to_create_worker(gcwq));
+			return true;
+		}
+
+		if (!need_to_create_worker(gcwq))
+			break;
 
-	if (cwq->wq->freezeable)
-		set_freezable();
+		__set_current_state(TASK_INTERRUPTIBLE);
+		schedule_timeout(CREATE_COOLDOWN);
+
+		if (!need_to_create_worker(gcwq))
+			break;
+	}
+
+	del_timer_sync(&gcwq->mayday_timer);
+	spin_lock_irq(&gcwq->lock);
+	if (need_to_create_worker(gcwq))
+		goto restart;
+	return true;
+}
+
+/**
+ * maybe_destroy_worker - destroy workers which have been idle for a while
+ * @gcwq: gcwq to destroy workers for
+ *
+ * Destroy @gcwq workers which have been idle for longer than
+ * IDLE_WORKER_TIMEOUT.
+ *
+ * LOCKING:
+ * spin_lock_irq(gcwq->lock) which may be released and regrabbed
+ * multiple times.  Called only from manager.
+ *
+ * RETURNS:
+ * false if no action was taken and gcwq->lock stayed locked, true
+ * otherwise.
+ */
+static bool maybe_destroy_workers(struct global_cwq *gcwq)
+{
+	bool ret = false;
 
-	for (;;) {
-		prepare_to_wait(&cwq->more_work, &wait, TASK_INTERRUPTIBLE);
-		if (!freezing(current) &&
-		    !kthread_should_stop() &&
-		    list_empty(&cwq->worklist))
-			schedule();
-		finish_wait(&cwq->more_work, &wait);
+	while (too_many_workers(gcwq)) {
+		struct worker *worker;
+		unsigned long expires;
 
-		try_to_freeze();
+		worker = list_entry(gcwq->idle_list.prev, struct worker, entry);
+		expires = worker->last_active + IDLE_WORKER_TIMEOUT;
 
-		if (kthread_should_stop())
+		if (time_before(jiffies, expires)) {
+			mod_timer(&gcwq->idle_timer, expires);
 			break;
+		}
 
-		run_workqueue(cwq);
+		destroy_worker(worker);
+		ret = true;
 	}
 
-	return 0;
+	return ret;
+}
+
+/**
+ * manage_workers - manage worker pool
+ * @worker: self
+ *
+ * Assume the manager role and manage gcwq worker pool @worker belongs
+ * to.  At any given time, there can be only zero or one manager per
+ * gcwq.  The exclusion is handled automatically by this function.
+ *
+ * The caller can safely start processing works on false return.  On
+ * true return, it's guaranteed that need_to_create_worker() is false
+ * and may_start_working() is true.
+ *
+ * CONTEXT:
+ * spin_lock_irq(gcwq->lock) which may be released and regrabbed
+ * multiple times.  Does GFP_KERNEL allocations.
+ *
+ * RETURNS:
+ * false if no action was taken and gcwq->lock stayed locked, true if
+ * some action was taken.
+ */
+static bool manage_workers(struct worker *worker)
+{
+	struct global_cwq *gcwq = worker->gcwq;
+	bool ret = false;
+
+	if (gcwq->flags & GCWQ_MANAGING_WORKERS)
+		return ret;
+
+	gcwq->flags &= ~GCWQ_MANAGE_WORKERS;
+	gcwq->flags |= GCWQ_MANAGING_WORKERS;
+
+	/*
+	 * Destroy and then create so that may_start_working() is true
+	 * on return.
+	 */
+	ret |= maybe_destroy_workers(gcwq);
+	ret |= maybe_create_worker(gcwq);
+
+	gcwq->flags &= ~GCWQ_MANAGING_WORKERS;
+
+	/*
+	 * The trustee might be waiting to take over the manager
+	 * position, tell it we're done.
+	 */
+	if (unlikely(gcwq->trustee))
+		wake_up_all(&gcwq->trustee_wait);
+
+	return ret;
+}
+
+/**
+ * move_linked_works - move linked works to a list
+ * @work: start of series of works to be scheduled
+ * @head: target list to append @work to
+ * @nextp: out paramter for nested worklist walking
+ *
+ * Schedule linked works starting from @work to @head.  Work series to
+ * be scheduled starts at @work and includes any consecutive work with
+ * WORK_STRUCT_LINKED set in its predecessor.
+ *
+ * If @nextp is not NULL, it's updated to point to the next work of
+ * the last scheduled work.  This allows move_linked_works() to be
+ * nested inside outer list_for_each_entry_safe().
+ *
+ * CONTEXT:
+ * spin_lock_irq(gcwq->lock).
+ */
+static void move_linked_works(struct work_struct *work, struct list_head *head,
+			      struct work_struct **nextp)
+{
+	struct work_struct *n;
+
+	/*
+	 * Linked worklist will always end before the end of the list,
+	 * use NULL for list head.
+	 */
+	list_for_each_entry_safe_from(work, n, NULL, entry) {
+		list_move_tail(&work->entry, head);
+		if (!(*work_data_bits(work) & WORK_STRUCT_LINKED))
+			break;
+	}
+
+	/*
+	 * If we're already inside safe list traversal and have moved
+	 * multiple works to the scheduled queue, the next position
+	 * needs to be updated.
+	 */
+	if (nextp)
+		*nextp = n;
+}
+
+static void cwq_activate_first_delayed(struct cpu_workqueue_struct *cwq)
+{
+	struct work_struct *work = list_first_entry(&cwq->delayed_works,
+						    struct work_struct, entry);
+	struct list_head *pos = gcwq_determine_ins_pos(cwq->gcwq, cwq);
+
+	move_linked_works(work, pos, NULL);
+	cwq->nr_active++;
+}
+
+/**
+ * cwq_dec_nr_in_flight - decrement cwq's nr_in_flight
+ * @cwq: cwq of interest
+ * @color: color of work which left the queue
+ *
+ * A work either has completed or is removed from pending queue,
+ * decrement nr_in_flight of its cwq and handle workqueue flushing.
+ *
+ * CONTEXT:
+ * spin_lock_irq(gcwq->lock).
+ */
+static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct *cwq, int color)
+{
+	/* ignore uncolored works */
+	if (color == WORK_NO_COLOR)
+		return;
+
+	cwq->nr_in_flight[color]--;
+	cwq->nr_active--;
+
+	if (!list_empty(&cwq->delayed_works)) {
+		/* one down, submit a delayed one */
+		if (cwq->nr_active < cwq->max_active)
+			cwq_activate_first_delayed(cwq);
+	}
+
+	/* is flush in progress and are we at the flushing tip? */
+	if (likely(cwq->flush_color != color))
+		return;
+
+	/* are there still in-flight works? */
+	if (cwq->nr_in_flight[color])
+		return;
+
+	/* this cwq is done, clear flush_color */
+	cwq->flush_color = -1;
+
+	/*
+	 * If this was the last cwq, wake up the first flusher.  It
+	 * will handle the rest.
+	 */
+	if (atomic_dec_and_test(&cwq->wq->nr_cwqs_to_flush))
+		complete(&cwq->wq->first_flusher->done);
+}
+
+/**
+ * process_one_work - process single work
+ * @worker: self
+ * @work: work to process
+ *
+ * Process @work.  This function contains all the logics necessary to
+ * process a single work including synchronization against and
+ * interaction with other workers on the same cpu, queueing and
+ * flushing.  As long as context requirement is met, any worker can
+ * call this function to process a work.
+ *
+ * CONTEXT:
+ * spin_lock_irq(gcwq->lock) which is released and regrabbed.
+ */
+static void process_one_work(struct worker *worker, struct work_struct *work)
+{
+	struct cpu_workqueue_struct *cwq = get_work_cwq(work);
+	struct global_cwq *gcwq = cwq->gcwq;
+	struct hlist_head *bwh = busy_worker_head(gcwq, work);
+	bool cpu_intensive = cwq->wq->flags & WQ_CPU_INTENSIVE;
+	work_func_t f = work->func;
+	int work_color;
+	struct worker *collision;
+#ifdef CONFIG_LOCKDEP
+	/*
+	 * It is permissible to free the struct work_struct from
+	 * inside the function that is called from it, this we need to
+	 * take into account for lockdep too.  To avoid bogus "held
+	 * lock freed" warnings as well as problems when looking into
+	 * work->lockdep_map, make a copy and use that here.
+	 */
+	struct lockdep_map lockdep_map = work->lockdep_map;
+#endif
+	/*
+	 * A single work shouldn't be executed concurrently by
+	 * multiple workers on a single cpu.  Check whether anyone is
+	 * already processing the work.  If so, defer the work to the
+	 * currently executing one.
+	 */
+	collision = __find_worker_executing_work(gcwq, bwh, work);
+	if (unlikely(collision)) {
+		move_linked_works(work, &collision->scheduled, NULL);
+		return;
+	}
+
+	/* claim and process */
+	debug_work_deactivate(work);
+	hlist_add_head(&worker->hentry, bwh);
+	worker->current_work = work;
+	worker->current_cwq = cwq;
+	work_color = get_work_color(work);
+
+	/* record the current cpu number in the work data and dequeue */
+	set_work_cpu(work, gcwq->cpu);
+	list_del_init(&work->entry);
+
+	/*
+	 * If HIGHPRI_PENDING, check the next work, and, if HIGHPRI,
+	 * wake up another worker; otherwise, clear HIGHPRI_PENDING.
+	 */
+	if (unlikely(gcwq->flags & GCWQ_HIGHPRI_PENDING)) {
+		struct work_struct *nwork = list_first_entry(&gcwq->worklist,
+						struct work_struct, entry);
+
+		if (!list_empty(&gcwq->worklist) &&
+		    get_work_cwq(nwork)->wq->flags & WQ_HIGHPRI)
+			wake_up_worker(gcwq);
+		else
+			gcwq->flags &= ~GCWQ_HIGHPRI_PENDING;
+	}
+
+	/*
+	 * CPU intensive works don't participate in concurrency
+	 * management.  They're the scheduler's responsibility.
+	 */
+	if (unlikely(cpu_intensive))
+		worker_set_flags(worker, WORKER_CPU_INTENSIVE, true);
+
+	spin_unlock_irq(&gcwq->lock);
+
+	work_clear_pending(work);
+	lock_map_acquire(&cwq->wq->lockdep_map);
+	lock_map_acquire(&lockdep_map);
+	f(work);
+	lock_map_release(&lockdep_map);
+	lock_map_release(&cwq->wq->lockdep_map);
+
+	if (unlikely(in_atomic() || lockdep_depth(current) > 0)) {
+		printk(KERN_ERR "BUG: workqueue leaked lock or atomic: "
+		       "%s/0x%08x/%d\n",
+		       current->comm, preempt_count(), task_pid_nr(current));
+		printk(KERN_ERR "    last function: ");
+		print_symbol("%s\n", (unsigned long)f);
+		debug_show_held_locks(current);
+		dump_stack();
+	}
+
+	spin_lock_irq(&gcwq->lock);
+
+	/* clear cpu intensive status */
+	if (unlikely(cpu_intensive))
+		worker_clr_flags(worker, WORKER_CPU_INTENSIVE);
+
+	/* we're done with it, release */
+	hlist_del_init(&worker->hentry);
+	worker->current_work = NULL;
+	worker->current_cwq = NULL;
+	cwq_dec_nr_in_flight(cwq, work_color);
+}
+
+/**
+ * process_scheduled_works - process scheduled works
+ * @worker: self
+ *
+ * Process all scheduled works.  Please note that the scheduled list
+ * may change while processing a work, so this function repeatedly
+ * fetches a work from the top and executes it.
+ *
+ * CONTEXT:
+ * spin_lock_irq(gcwq->lock) which may be released and regrabbed
+ * multiple times.
+ */
+static void process_scheduled_works(struct worker *worker)
+{
+	while (!list_empty(&worker->scheduled)) {
+		struct work_struct *work = list_first_entry(&worker->scheduled,
+						struct work_struct, entry);
+		process_one_work(worker, work);
+	}
+}
+
+/**
+ * worker_thread - the worker thread function
+ * @__worker: self
+ *
+ * The gcwq worker thread function.  There's a single dynamic pool of
+ * these per each cpu.  These workers process all works regardless of
+ * their specific target workqueue.  The only exception is works which
+ * belong to workqueues with a rescuer which will be explained in
+ * rescuer_thread().
+ */
+static int worker_thread(void *__worker)
+{
+	struct worker *worker = __worker;
+	struct global_cwq *gcwq = worker->gcwq;
+
+	/* tell the scheduler that this is a workqueue worker */
+	worker->task->flags |= PF_WQ_WORKER;
+woke_up:
+	spin_lock_irq(&gcwq->lock);
+
+	/* DIE can be set only while we're idle, checking here is enough */
+	if (worker->flags & WORKER_DIE) {
+		spin_unlock_irq(&gcwq->lock);
+		worker->task->flags &= ~PF_WQ_WORKER;
+		return 0;
+	}
+
+	worker_leave_idle(worker);
+recheck:
+	/* no more worker necessary? */
+	if (!need_more_worker(gcwq))
+		goto sleep;
+
+	/* do we need to manage? */
+	if (unlikely(!may_start_working(gcwq)) && manage_workers(worker))
+		goto recheck;
+
+	/*
+	 * ->scheduled list can only be filled while a worker is
+	 * preparing to process a work or actually processing it.
+	 * Make sure nobody diddled with it while I was sleeping.
+	 */
+	BUG_ON(!list_empty(&worker->scheduled));
+
+	/*
+	 * When control reaches this point, we're guaranteed to have
+	 * at least one idle worker or that someone else has already
+	 * assumed the manager role.
+	 */
+	worker_clr_flags(worker, WORKER_PREP);
+
+	do {
+		struct work_struct *work =
+			list_first_entry(&gcwq->worklist,
+					 struct work_struct, entry);
+
+		if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) {
+			/* optimization path, not strictly necessary */
+			process_one_work(worker, work);
+			if (unlikely(!list_empty(&worker->scheduled)))
+				process_scheduled_works(worker);
+		} else {
+			move_linked_works(work, &worker->scheduled, NULL);
+			process_scheduled_works(worker);
+		}
+	} while (keep_working(gcwq));
+
+	worker_set_flags(worker, WORKER_PREP, false);
+sleep:
+	if (unlikely(need_to_manage_workers(gcwq)) && manage_workers(worker))
+		goto recheck;
+
+	/*
+	 * gcwq->lock is held and there's no work to process and no
+	 * need to manage, sleep.  Workers are woken up only while
+	 * holding gcwq->lock or from local cpu, so setting the
+	 * current state before releasing gcwq->lock is enough to
+	 * prevent losing any event.
+	 */
+	worker_enter_idle(worker);
+	__set_current_state(TASK_INTERRUPTIBLE);
+	spin_unlock_irq(&gcwq->lock);
+	schedule();
+	goto woke_up;
+}
+
+/**
+ * rescuer_thread - the rescuer thread function
+ * @__wq: the associated workqueue
+ *
+ * Workqueue rescuer thread function.  There's one rescuer for each
+ * workqueue which has WQ_RESCUER set.
+ *
+ * Regular work processing on a gcwq may block trying to create a new
+ * worker which uses GFP_KERNEL allocation which has slight chance of
+ * developing into deadlock if some works currently on the same queue
+ * need to be processed to satisfy the GFP_KERNEL allocation.  This is
+ * the problem rescuer solves.
+ *
+ * When such condition is possible, the gcwq summons rescuers of all
+ * workqueues which have works queued on the gcwq and let them process
+ * those works so that forward progress can be guaranteed.
+ *
+ * This should happen rarely.
+ */
+static int rescuer_thread(void *__wq)
+{
+	struct workqueue_struct *wq = __wq;
+	struct worker *rescuer = wq->rescuer;
+	struct list_head *scheduled = &rescuer->scheduled;
+	bool is_unbound = wq->flags & WQ_UNBOUND;
+	unsigned int cpu;
+
+	set_user_nice(current, RESCUER_NICE_LEVEL);
+repeat:
+	set_current_state(TASK_INTERRUPTIBLE);
+
+	if (kthread_should_stop())
+		return 0;
+
+	/*
+	 * See whether any cpu is asking for help.  Unbounded
+	 * workqueues use cpu 0 in mayday_mask for CPU_UNBOUND.
+	 */
+	for_each_mayday_cpu(cpu, wq->mayday_mask) {
+		unsigned int tcpu = is_unbound ? WORK_CPU_UNBOUND : cpu;
+		struct cpu_workqueue_struct *cwq = get_cwq(tcpu, wq);
+		struct global_cwq *gcwq = cwq->gcwq;
+		struct work_struct *work, *n;
+
+		__set_current_state(TASK_RUNNING);
+		mayday_clear_cpu(cpu, wq->mayday_mask);
+
+		/* migrate to the target cpu if possible */
+		rescuer->gcwq = gcwq;
+		worker_maybe_bind_and_lock(rescuer);
+
+		/*
+		 * Slurp in all works issued via this workqueue and
+		 * process'em.
+		 */
+		BUG_ON(!list_empty(&rescuer->scheduled));
+		list_for_each_entry_safe(work, n, &gcwq->worklist, entry)
+			if (get_work_cwq(work) == cwq)
+				move_linked_works(work, scheduled, &n);
+
+		process_scheduled_works(rescuer);
+		spin_unlock_irq(&gcwq->lock);
+	}
+
+	schedule();
+	goto repeat;
 }
 
 struct wq_barrier {
@@ -484,44 +2003,137 @@ static void wq_barrier_func(struct work_struct *work)
 	complete(&barr->done);
 }
 
+/**
+ * insert_wq_barrier - insert a barrier work
+ * @cwq: cwq to insert barrier into
+ * @barr: wq_barrier to insert
+ * @target: target work to attach @barr to
+ * @worker: worker currently executing @target, NULL if @target is not executing
+ *
+ * @barr is linked to @target such that @barr is completed only after
+ * @target finishes execution.  Please note that the ordering
+ * guarantee is observed only with respect to @target and on the local
+ * cpu.
+ *
+ * Currently, a queued barrier can't be canceled.  This is because
+ * try_to_grab_pending() can't determine whether the work to be
+ * grabbed is at the head of the queue and thus can't clear LINKED
+ * flag of the previous work while there must be a valid next work
+ * after a work with LINKED flag set.
+ *
+ * Note that when @worker is non-NULL, @target may be modified
+ * underneath us, so we can't reliably determine cwq from @target.
+ *
+ * CONTEXT:
+ * spin_lock_irq(gcwq->lock).
+ */
 static void insert_wq_barrier(struct cpu_workqueue_struct *cwq,
-			struct wq_barrier *barr, struct list_head *head)
+			      struct wq_barrier *barr,
+			      struct work_struct *target, struct worker *worker)
 {
+	struct list_head *head;
+	unsigned int linked = 0;
+
 	/*
-	 * debugobject calls are safe here even with cwq->lock locked
+	 * debugobject calls are safe here even with gcwq->lock locked
 	 * as we know for sure that this will not trigger any of the
 	 * checks and call back into the fixup functions where we
 	 * might deadlock.
 	 */
 	INIT_WORK_ON_STACK(&barr->work, wq_barrier_func);
-	__set_bit(WORK_STRUCT_PENDING, work_data_bits(&barr->work));
+	__set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work));
+	init_completion(&barr->done);
+
+	/*
+	 * If @target is currently being executed, schedule the
+	 * barrier to the worker; otherwise, put it after @target.
+	 */
+	if (worker)
+		head = worker->scheduled.next;
+	else {
+		unsigned long *bits = work_data_bits(target);
+
+		head = target->entry.next;
+		/* there can already be other linked works, inherit and set */
+		linked = *bits & WORK_STRUCT_LINKED;
+		__set_bit(WORK_STRUCT_LINKED_BIT, bits);
+	}
+
+	debug_work_activate(&barr->work);
+	insert_work(cwq, &barr->work, head,
+		    work_color_to_flags(WORK_NO_COLOR) | linked);
+}
+
+/**
+ * flush_workqueue_prep_cwqs - prepare cwqs for workqueue flushing
+ * @wq: workqueue being flushed
+ * @flush_color: new flush color, < 0 for no-op
+ * @work_color: new work color, < 0 for no-op
+ *
+ * Prepare cwqs for workqueue flushing.
+ *
+ * If @flush_color is non-negative, flush_color on all cwqs should be
+ * -1.  If no cwq has in-flight commands at the specified color, all
+ * cwq->flush_color's stay at -1 and %false is returned.  If any cwq
+ * has in flight commands, its cwq->flush_color is set to
+ * @flush_color, @wq->nr_cwqs_to_flush is updated accordingly, cwq
+ * wakeup logic is armed and %true is returned.
+ *
+ * The caller should have initialized @wq->first_flusher prior to
+ * calling this function with non-negative @flush_color.  If
+ * @flush_color is negative, no flush color update is done and %false
+ * is returned.
+ *
+ * If @work_color is non-negative, all cwqs should have the same
+ * work_color which is previous to @work_color and all will be
+ * advanced to @work_color.
+ *
+ * CONTEXT:
+ * mutex_lock(wq->flush_mutex).
+ *
+ * RETURNS:
+ * %true if @flush_color >= 0 and there's something to flush.  %false
+ * otherwise.
+ */
+static bool flush_workqueue_prep_cwqs(struct workqueue_struct *wq,
+				      int flush_color, int work_color)
+{
+	bool wait = false;
+	unsigned int cpu;
+
+	if (flush_color >= 0) {
+		BUG_ON(atomic_read(&wq->nr_cwqs_to_flush));
+		atomic_set(&wq->nr_cwqs_to_flush, 1);
+	}
+
+	for_each_cwq_cpu(cpu, wq) {
+		struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
+		struct global_cwq *gcwq = cwq->gcwq;
 
-	init_completion(&barr->done);
+		spin_lock_irq(&gcwq->lock);
 
-	debug_work_activate(&barr->work);
-	insert_work(cwq, &barr->work, head);
-}
+		if (flush_color >= 0) {
+			BUG_ON(cwq->flush_color != -1);
 
-static int flush_cpu_workqueue(struct cpu_workqueue_struct *cwq)
-{
-	int active = 0;
-	struct wq_barrier barr;
+			if (cwq->nr_in_flight[flush_color]) {
+				cwq->flush_color = flush_color;
+				atomic_inc(&wq->nr_cwqs_to_flush);
+				wait = true;
+			}
+		}
 
-	WARN_ON(cwq->thread == current);
+		if (work_color >= 0) {
+			BUG_ON(work_color != work_next_color(cwq->work_color));
+			cwq->work_color = work_color;
+		}
 
-	spin_lock_irq(&cwq->lock);
-	if (!list_empty(&cwq->worklist) || cwq->current_work != NULL) {
-		insert_wq_barrier(cwq, &barr, &cwq->worklist);
-		active = 1;
+		spin_unlock_irq(&gcwq->lock);
 	}
-	spin_unlock_irq(&cwq->lock);
 
-	if (active) {
-		wait_for_completion(&barr.done);
-		destroy_work_on_stack(&barr.work);
-	}
+	if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_cwqs_to_flush))
+		complete(&wq->first_flusher->done);
 
-	return active;
+	return wait;
 }
 
 /**
@@ -533,20 +2145,150 @@ static int flush_cpu_workqueue(struct cpu_workqueue_struct *cwq)
  *
  * We sleep until all works which were queued on entry have been handled,
  * but we are not livelocked by new incoming ones.
- *
- * This function used to run the workqueues itself.  Now we just wait for the
- * helper threads to do it.
  */
 void flush_workqueue(struct workqueue_struct *wq)
 {
-	const struct cpumask *cpu_map = wq_cpu_map(wq);
-	int cpu;
+	struct wq_flusher this_flusher = {
+		.list = LIST_HEAD_INIT(this_flusher.list),
+		.flush_color = -1,
+		.done = COMPLETION_INITIALIZER_ONSTACK(this_flusher.done),
+	};
+	int next_color;
 
-	might_sleep();
 	lock_map_acquire(&wq->lockdep_map);
 	lock_map_release(&wq->lockdep_map);
-	for_each_cpu(cpu, cpu_map)
-		flush_cpu_workqueue(per_cpu_ptr(wq->cpu_wq, cpu));
+
+	mutex_lock(&wq->flush_mutex);
+
+	/*
+	 * Start-to-wait phase
+	 */
+	next_color = work_next_color(wq->work_color);
+
+	if (next_color != wq->flush_color) {
+		/*
+		 * Color space is not full.  The current work_color
+		 * becomes our flush_color and work_color is advanced
+		 * by one.
+		 */
+		BUG_ON(!list_empty(&wq->flusher_overflow));
+		this_flusher.flush_color = wq->work_color;
+		wq->work_color = next_color;
+
+		if (!wq->first_flusher) {
+			/* no flush in progress, become the first flusher */
+			BUG_ON(wq->flush_color != this_flusher.flush_color);
+
+			wq->first_flusher = &this_flusher;
+
+			if (!flush_workqueue_prep_cwqs(wq, wq->flush_color,
+						       wq->work_color)) {
+				/* nothing to flush, done */
+				wq->flush_color = next_color;
+				wq->first_flusher = NULL;
+				goto out_unlock;
+			}
+		} else {
+			/* wait in queue */
+			BUG_ON(wq->flush_color == this_flusher.flush_color);
+			list_add_tail(&this_flusher.list, &wq->flusher_queue);
+			flush_workqueue_prep_cwqs(wq, -1, wq->work_color);
+		}
+	} else {
+		/*
+		 * Oops, color space is full, wait on overflow queue.
+		 * The next flush completion will assign us
+		 * flush_color and transfer to flusher_queue.
+		 */
+		list_add_tail(&this_flusher.list, &wq->flusher_overflow);
+	}
+
+	mutex_unlock(&wq->flush_mutex);
+
+	wait_for_completion(&this_flusher.done);
+
+	/*
+	 * Wake-up-and-cascade phase
+	 *
+	 * First flushers are responsible for cascading flushes and
+	 * handling overflow.  Non-first flushers can simply return.
+	 */
+	if (wq->first_flusher != &this_flusher)
+		return;
+
+	mutex_lock(&wq->flush_mutex);
+
+	/* we might have raced, check again with mutex held */
+	if (wq->first_flusher != &this_flusher)
+		goto out_unlock;
+
+	wq->first_flusher = NULL;
+
+	BUG_ON(!list_empty(&this_flusher.list));
+	BUG_ON(wq->flush_color != this_flusher.flush_color);
+
+	while (true) {
+		struct wq_flusher *next, *tmp;
+
+		/* complete all the flushers sharing the current flush color */
+		list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) {
+			if (next->flush_color != wq->flush_color)
+				break;
+			list_del_init(&next->list);
+			complete(&next->done);
+		}
+
+		BUG_ON(!list_empty(&wq->flusher_overflow) &&
+		       wq->flush_color != work_next_color(wq->work_color));
+
+		/* this flush_color is finished, advance by one */
+		wq->flush_color = work_next_color(wq->flush_color);
+
+		/* one color has been freed, handle overflow queue */
+		if (!list_empty(&wq->flusher_overflow)) {
+			/*
+			 * Assign the same color to all overflowed
+			 * flushers, advance work_color and append to
+			 * flusher_queue.  This is the start-to-wait
+			 * phase for these overflowed flushers.
+			 */
+			list_for_each_entry(tmp, &wq->flusher_overflow, list)
+				tmp->flush_color = wq->work_color;
+
+			wq->work_color = work_next_color(wq->work_color);
+
+			list_splice_tail_init(&wq->flusher_overflow,
+					      &wq->flusher_queue);
+			flush_workqueue_prep_cwqs(wq, -1, wq->work_color);
+		}
+
+		if (list_empty(&wq->flusher_queue)) {
+			BUG_ON(wq->flush_color != wq->work_color);
+			break;
+		}
+
+		/*
+		 * Need to flush more colors.  Make the next flusher
+		 * the new first flusher and arm cwqs.
+		 */
+		BUG_ON(wq->flush_color == wq->work_color);
+		BUG_ON(wq->flush_color != next->flush_color);
+
+		list_del_init(&next->list);
+		wq->first_flusher = next;
+
+		if (flush_workqueue_prep_cwqs(wq, wq->flush_color, -1))
+			break;
+
+		/*
+		 * Meh... this color is already done, clear first
+		 * flusher and repeat cascading.
+		 */
+		wq->first_flusher = NULL;
+	}
+
+out_unlock:
+	mutex_unlock(&wq->flush_mutex);
 }
 EXPORT_SYMBOL_GPL(flush_workqueue);
 
@@ -562,43 +2304,46 @@ EXPORT_SYMBOL_GPL(flush_workqueue);
  */
 int flush_work(struct work_struct *work)
 {
+	struct worker *worker = NULL;
+	struct global_cwq *gcwq;
 	struct cpu_workqueue_struct *cwq;
-	struct list_head *prev;
 	struct wq_barrier barr;
 
 	might_sleep();
-	cwq = get_wq_data(work);
-	if (!cwq)
+	gcwq = get_work_gcwq(work);
+	if (!gcwq)
 		return 0;
 
-	lock_map_acquire(&cwq->wq->lockdep_map);
-	lock_map_release(&cwq->wq->lockdep_map);
-
-	prev = NULL;
-	spin_lock_irq(&cwq->lock);
+	spin_lock_irq(&gcwq->lock);
 	if (!list_empty(&work->entry)) {
 		/*
 		 * See the comment near try_to_grab_pending()->smp_rmb().
-		 * If it was re-queued under us we are not going to wait.
+		 * If it was re-queued to a different gcwq under us, we
+		 * are not going to wait.
 		 */
 		smp_rmb();
-		if (unlikely(cwq != get_wq_data(work)))
-			goto out;
-		prev = &work->entry;
+		cwq = get_work_cwq(work);
+		if (unlikely(!cwq || gcwq != cwq->gcwq))
+			goto already_gone;
 	} else {
-		if (cwq->current_work != work)
-			goto out;
-		prev = &cwq->worklist;
+		worker = find_worker_executing_work(gcwq, work);
+		if (!worker)
+			goto already_gone;
+		cwq = worker->current_cwq;
 	}
-	insert_wq_barrier(cwq, &barr, prev->next);
-out:
-	spin_unlock_irq(&cwq->lock);
-	if (!prev)
-		return 0;
+
+	insert_wq_barrier(cwq, &barr, work, worker);
+	spin_unlock_irq(&gcwq->lock);
+
+	lock_map_acquire(&cwq->wq->lockdep_map);
+	lock_map_release(&cwq->wq->lockdep_map);
 
 	wait_for_completion(&barr.done);
 	destroy_work_on_stack(&barr.work);
 	return 1;
+already_gone:
+	spin_unlock_irq(&gcwq->lock);
+	return 0;
 }
 EXPORT_SYMBOL_GPL(flush_work);
 
@@ -608,54 +2353,55 @@ EXPORT_SYMBOL_GPL(flush_work);
  */
 static int try_to_grab_pending(struct work_struct *work)
 {
-	struct cpu_workqueue_struct *cwq;
+	struct global_cwq *gcwq;
 	int ret = -1;
 
-	if (!test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(work)))
+	if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work)))
 		return 0;
 
 	/*
 	 * The queueing is in progress, or it is already queued. Try to
 	 * steal it from ->worklist without clearing WORK_STRUCT_PENDING.
 	 */
-
-	cwq = get_wq_data(work);
-	if (!cwq)
+	gcwq = get_work_gcwq(work);
+	if (!gcwq)
 		return ret;
 
-	spin_lock_irq(&cwq->lock);
+	spin_lock_irq(&gcwq->lock);
 	if (!list_empty(&work->entry)) {
 		/*
-		 * This work is queued, but perhaps we locked the wrong cwq.
+		 * This work is queued, but perhaps we locked the wrong gcwq.
 		 * In that case we must see the new value after rmb(), see
 		 * insert_work()->wmb().
 		 */
 		smp_rmb();
-		if (cwq == get_wq_data(work)) {
+		if (gcwq == get_work_gcwq(work)) {
 			debug_work_deactivate(work);
 			list_del_init(&work->entry);
+			cwq_dec_nr_in_flight(get_work_cwq(work),
+					     get_work_color(work));
 			ret = 1;
 		}
 	}
-	spin_unlock_irq(&cwq->lock);
+	spin_unlock_irq(&gcwq->lock);
 
 	return ret;
 }
 
-static void wait_on_cpu_work(struct cpu_workqueue_struct *cwq,
-				struct work_struct *work)
+static void wait_on_cpu_work(struct global_cwq *gcwq, struct work_struct *work)
 {
 	struct wq_barrier barr;
-	int running = 0;
+	struct worker *worker;
 
-	spin_lock_irq(&cwq->lock);
-	if (unlikely(cwq->current_work == work)) {
-		insert_wq_barrier(cwq, &barr, cwq->worklist.next);
-		running = 1;
-	}
-	spin_unlock_irq(&cwq->lock);
+	spin_lock_irq(&gcwq->lock);
 
-	if (unlikely(running)) {
+	worker = find_worker_executing_work(gcwq, work);
+	if (unlikely(worker))
+		insert_wq_barrier(worker->current_cwq, &barr, work, worker);
+
+	spin_unlock_irq(&gcwq->lock);
+
+	if (unlikely(worker)) {
 		wait_for_completion(&barr.done);
 		destroy_work_on_stack(&barr.work);
 	}
@@ -663,9 +2409,6 @@ static void wait_on_cpu_work(struct cpu_workqueue_struct *cwq,
 
 static void wait_on_work(struct work_struct *work)
 {
-	struct cpu_workqueue_struct *cwq;
-	struct workqueue_struct *wq;
-	const struct cpumask *cpu_map;
 	int cpu;
 
 	might_sleep();
@@ -673,15 +2416,8 @@ static void wait_on_work(struct work_struct *work)
 	lock_map_acquire(&work->lockdep_map);
 	lock_map_release(&work->lockdep_map);
 
-	cwq = get_wq_data(work);
-	if (!cwq)
-		return;
-
-	wq = cwq->wq;
-	cpu_map = wq_cpu_map(wq);
-
-	for_each_cpu(cpu, cpu_map)
-		wait_on_cpu_work(per_cpu_ptr(wq->cpu_wq, cpu), work);
+	for_each_gcwq_cpu(cpu)
+		wait_on_cpu_work(get_gcwq(cpu), work);
 }
 
 static int __cancel_work_timer(struct work_struct *work,
@@ -696,7 +2432,7 @@ static int __cancel_work_timer(struct work_struct *work,
 		wait_on_work(work);
 	} while (unlikely(ret < 0));
 
-	clear_wq_data(work);
+	clear_work_data(work);
 	return ret;
 }
 
@@ -742,8 +2478,6 @@ int cancel_delayed_work_sync(struct delayed_work *dwork)
 }
 EXPORT_SYMBOL(cancel_delayed_work_sync);
 
-static struct workqueue_struct *keventd_wq __read_mostly;
-
 /**
  * schedule_work - put work task in global workqueue
  * @work: job to be done
@@ -757,7 +2491,7 @@ static struct workqueue_struct *keventd_wq __read_mostly;
  */
 int schedule_work(struct work_struct *work)
 {
-	return queue_work(keventd_wq, work);
+	return queue_work(system_wq, work);
 }
 EXPORT_SYMBOL(schedule_work);
 
@@ -770,7 +2504,7 @@ EXPORT_SYMBOL(schedule_work);
  */
 int schedule_work_on(int cpu, struct work_struct *work)
 {
-	return queue_work_on(cpu, keventd_wq, work);
+	return queue_work_on(cpu, system_wq, work);
 }
 EXPORT_SYMBOL(schedule_work_on);
 
@@ -785,7 +2519,7 @@ EXPORT_SYMBOL(schedule_work_on);
 int schedule_delayed_work(struct delayed_work *dwork,
 					unsigned long delay)
 {
-	return queue_delayed_work(keventd_wq, dwork, delay);
+	return queue_delayed_work(system_wq, dwork, delay);
 }
 EXPORT_SYMBOL(schedule_delayed_work);
 
@@ -798,9 +2532,8 @@ EXPORT_SYMBOL(schedule_delayed_work);
 void flush_delayed_work(struct delayed_work *dwork)
 {
 	if (del_timer_sync(&dwork->timer)) {
-		struct cpu_workqueue_struct *cwq;
-		cwq = wq_per_cpu(get_wq_data(&dwork->work)->wq, get_cpu());
-		__queue_work(cwq, &dwork->work);
+		__queue_work(get_cpu(), get_work_cwq(&dwork->work)->wq,
+			     &dwork->work);
 		put_cpu();
 	}
 	flush_work(&dwork->work);
@@ -819,7 +2552,7 @@ EXPORT_SYMBOL(flush_delayed_work);
 int schedule_delayed_work_on(int cpu,
 			struct delayed_work *dwork, unsigned long delay)
 {
-	return queue_delayed_work_on(cpu, keventd_wq, dwork, delay);
+	return queue_delayed_work_on(cpu, system_wq, dwork, delay);
 }
 EXPORT_SYMBOL(schedule_delayed_work_on);
 
@@ -835,7 +2568,6 @@ EXPORT_SYMBOL(schedule_delayed_work_on);
 int schedule_on_each_cpu(work_func_t func)
 {
 	int cpu;
-	int orig = -1;
 	struct work_struct *works;
 
 	works = alloc_percpu(struct work_struct);
@@ -844,329 +2576,762 @@ int schedule_on_each_cpu(work_func_t func)
 
 	get_online_cpus();
 
+	for_each_online_cpu(cpu) {
+		struct work_struct *work = per_cpu_ptr(works, cpu);
+
+		INIT_WORK(work, func);
+		schedule_work_on(cpu, work);
+	}
+
+	for_each_online_cpu(cpu)
+		flush_work(per_cpu_ptr(works, cpu));
+
+	put_online_cpus();
+	free_percpu(works);
+	return 0;
+}
+
+/**
+ * flush_scheduled_work - ensure that any scheduled work has run to completion.
+ *
+ * Forces execution of the kernel-global workqueue and blocks until its
+ * completion.
+ *
+ * Think twice before calling this function!  It's very easy to get into
+ * trouble if you don't take great care.  Either of the following situations
+ * will lead to deadlock:
+ *
+ *	One of the work items currently on the workqueue needs to acquire
+ *	a lock held by your code or its caller.
+ *
+ *	Your code is running in the context of a work routine.
+ *
+ * They will be detected by lockdep when they occur, but the first might not
+ * occur very often.  It depends on what work items are on the workqueue and
+ * what locks they need, which you have no control over.
+ *
+ * In most situations flushing the entire workqueue is overkill; you merely
+ * need to know that a particular work item isn't queued and isn't running.
+ * In such cases you should use cancel_delayed_work_sync() or
+ * cancel_work_sync() instead.
+ */
+void flush_scheduled_work(void)
+{
+	flush_workqueue(system_wq);
+}
+EXPORT_SYMBOL(flush_scheduled_work);
+
+/**
+ * execute_in_process_context - reliably execute the routine with user context
+ * @fn:		the function to execute
+ * @ew:		guaranteed storage for the execute work structure (must
+ *		be available when the work executes)
+ *
+ * Executes the function immediately if process context is available,
+ * otherwise schedules the function for delayed execution.
+ *
+ * Returns:	0 - function was executed
+ *		1 - function was scheduled for execution
+ */
+int execute_in_process_context(work_func_t fn, struct execute_work *ew)
+{
+	if (!in_interrupt()) {
+		fn(&ew->work);
+		return 0;
+	}
+
+	INIT_WORK(&ew->work, fn);
+	schedule_work(&ew->work);
+
+	return 1;
+}
+EXPORT_SYMBOL_GPL(execute_in_process_context);
+
+int keventd_up(void)
+{
+	return system_wq != NULL;
+}
+
+static int alloc_cwqs(struct workqueue_struct *wq)
+{
 	/*
-	 * When running in keventd don't schedule a work item on
-	 * itself.  Can just call directly because the work queue is
-	 * already bound.  This also is faster.
+	 * cwqs are forced aligned according to WORK_STRUCT_FLAG_BITS.
+	 * Make sure that the alignment isn't lower than that of
+	 * unsigned long long.
 	 */
-	if (current_is_keventd())
-		orig = raw_smp_processor_id();
+	const size_t size = sizeof(struct cpu_workqueue_struct);
+	const size_t align = max_t(size_t, 1 << WORK_STRUCT_FLAG_BITS,
+				   __alignof__(unsigned long long));
+#ifdef CONFIG_SMP
+	bool percpu = !(wq->flags & WQ_UNBOUND);
+#else
+	bool percpu = false;
+#endif
 
-	for_each_online_cpu(cpu) {
-		struct work_struct *work = per_cpu_ptr(works, cpu);
+	if (percpu)
+		wq->cpu_wq.pcpu = __alloc_percpu(size, align);
+	else {
+		void *ptr;
+
+		/*
+		 * Allocate enough room to align cwq and put an extra
+		 * pointer at the end pointing back to the originally
+		 * allocated pointer which will be used for free.
+		 */
+		ptr = kzalloc(size + align + sizeof(void *), GFP_KERNEL);
+		if (ptr) {
+			wq->cpu_wq.single = PTR_ALIGN(ptr, align);
+			*(void **)(wq->cpu_wq.single + 1) = ptr;
+		}
+	}
+
+	/* just in case, make sure it's actually aligned */
+	BUG_ON(!IS_ALIGNED(wq->cpu_wq.v, align));
+	return wq->cpu_wq.v ? 0 : -ENOMEM;
+}
+
+static void free_cwqs(struct workqueue_struct *wq)
+{
+#ifdef CONFIG_SMP
+	bool percpu = !(wq->flags & WQ_UNBOUND);
+#else
+	bool percpu = false;
+#endif
+
+	if (percpu)
+		free_percpu(wq->cpu_wq.pcpu);
+	else if (wq->cpu_wq.single) {
+		/* the pointer to free is stored right after the cwq */
+		kfree(*(void **)(wq->cpu_wq.single + 1));
+	}
+}
+
+static int wq_clamp_max_active(int max_active, unsigned int flags,
+			       const char *name)
+{
+	int lim = flags & WQ_UNBOUND ? WQ_UNBOUND_MAX_ACTIVE : WQ_MAX_ACTIVE;
+
+	if (max_active < 1 || max_active > lim)
+		printk(KERN_WARNING "workqueue: max_active %d requested for %s "
+		       "is out of range, clamping between %d and %d\n",
+		       max_active, name, 1, lim);
+
+	return clamp_val(max_active, 1, lim);
+}
+
+struct workqueue_struct *__alloc_workqueue_key(const char *name,
+					       unsigned int flags,
+					       int max_active,
+					       struct lock_class_key *key,
+					       const char *lock_name)
+{
+	struct workqueue_struct *wq;
+	unsigned int cpu;
+
+	/*
+	 * Unbound workqueues aren't concurrency managed and should be
+	 * dispatched to workers immediately.
+	 */
+	if (flags & WQ_UNBOUND)
+		flags |= WQ_HIGHPRI;
+
+	max_active = max_active ?: WQ_DFL_ACTIVE;
+	max_active = wq_clamp_max_active(max_active, flags, name);
+
+	wq = kzalloc(sizeof(*wq), GFP_KERNEL);
+	if (!wq)
+		goto err;
+
+	wq->flags = flags;
+	wq->saved_max_active = max_active;
+	mutex_init(&wq->flush_mutex);
+	atomic_set(&wq->nr_cwqs_to_flush, 0);
+	INIT_LIST_HEAD(&wq->flusher_queue);
+	INIT_LIST_HEAD(&wq->flusher_overflow);
+
+	wq->name = name;
+	lockdep_init_map(&wq->lockdep_map, lock_name, key, 0);
+	INIT_LIST_HEAD(&wq->list);
+
+	if (alloc_cwqs(wq) < 0)
+		goto err;
+
+	for_each_cwq_cpu(cpu, wq) {
+		struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
+		struct global_cwq *gcwq = get_gcwq(cpu);
+
+		BUG_ON((unsigned long)cwq & WORK_STRUCT_FLAG_MASK);
+		cwq->gcwq = gcwq;
+		cwq->wq = wq;
+		cwq->flush_color = -1;
+		cwq->max_active = max_active;
+		INIT_LIST_HEAD(&cwq->delayed_works);
+	}
+
+	if (flags & WQ_RESCUER) {
+		struct worker *rescuer;
+
+		if (!alloc_mayday_mask(&wq->mayday_mask, GFP_KERNEL))
+			goto err;
+
+		wq->rescuer = rescuer = alloc_worker();
+		if (!rescuer)
+			goto err;
+
+		rescuer->task = kthread_create(rescuer_thread, wq, "%s", name);
+		if (IS_ERR(rescuer->task))
+			goto err;
+
+		wq->rescuer = rescuer;
+		rescuer->task->flags |= PF_THREAD_BOUND;
+		wake_up_process(rescuer->task);
+	}
+
+	/*
+	 * workqueue_lock protects global freeze state and workqueues
+	 * list.  Grab it, set max_active accordingly and add the new
+	 * workqueue to workqueues list.
+	 */
+	spin_lock(&workqueue_lock);
+
+	if (workqueue_freezing && wq->flags & WQ_FREEZEABLE)
+		for_each_cwq_cpu(cpu, wq)
+			get_cwq(cpu, wq)->max_active = 0;
+
+	list_add(&wq->list, &workqueues);
+
+	spin_unlock(&workqueue_lock);
+
+	return wq;
+err:
+	if (wq) {
+		free_cwqs(wq);
+		free_mayday_mask(wq->mayday_mask);
+		kfree(wq->rescuer);
+		kfree(wq);
+	}
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(__alloc_workqueue_key);
+
+/**
+ * destroy_workqueue - safely terminate a workqueue
+ * @wq: target workqueue
+ *
+ * Safely destroy a workqueue. All work currently pending will be done first.
+ */
+void destroy_workqueue(struct workqueue_struct *wq)
+{
+	unsigned int cpu;
+
+	flush_workqueue(wq);
+
+	/*
+	 * wq list is used to freeze wq, remove from list after
+	 * flushing is complete in case freeze races us.
+	 */
+	spin_lock(&workqueue_lock);
+	list_del(&wq->list);
+	spin_unlock(&workqueue_lock);
+
+	/* sanity check */
+	for_each_cwq_cpu(cpu, wq) {
+		struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
+		int i;
+
+		for (i = 0; i < WORK_NR_COLORS; i++)
+			BUG_ON(cwq->nr_in_flight[i]);
+		BUG_ON(cwq->nr_active);
+		BUG_ON(!list_empty(&cwq->delayed_works));
+	}
+
+	if (wq->flags & WQ_RESCUER) {
+		kthread_stop(wq->rescuer->task);
+		free_mayday_mask(wq->mayday_mask);
+	}
+
+	free_cwqs(wq);
+	kfree(wq);
+}
+EXPORT_SYMBOL_GPL(destroy_workqueue);
+
+/**
+ * workqueue_set_max_active - adjust max_active of a workqueue
+ * @wq: target workqueue
+ * @max_active: new max_active value.
+ *
+ * Set max_active of @wq to @max_active.
+ *
+ * CONTEXT:
+ * Don't call from IRQ context.
+ */
+void workqueue_set_max_active(struct workqueue_struct *wq, int max_active)
+{
+	unsigned int cpu;
+
+	max_active = wq_clamp_max_active(max_active, wq->flags, wq->name);
+
+	spin_lock(&workqueue_lock);
+
+	wq->saved_max_active = max_active;
+
+	for_each_cwq_cpu(cpu, wq) {
+		struct global_cwq *gcwq = get_gcwq(cpu);
+
+		spin_lock_irq(&gcwq->lock);
+
+		if (!(wq->flags & WQ_FREEZEABLE) ||
+		    !(gcwq->flags & GCWQ_FREEZING))
+			get_cwq(gcwq->cpu, wq)->max_active = max_active;
 
-		INIT_WORK(work, func);
-		if (cpu != orig)
-			schedule_work_on(cpu, work);
+		spin_unlock_irq(&gcwq->lock);
 	}
-	if (orig >= 0)
-		func(per_cpu_ptr(works, orig));
-
-	for_each_online_cpu(cpu)
-		flush_work(per_cpu_ptr(works, cpu));
 
-	put_online_cpus();
-	free_percpu(works);
-	return 0;
+	spin_unlock(&workqueue_lock);
 }
+EXPORT_SYMBOL_GPL(workqueue_set_max_active);
 
 /**
- * flush_scheduled_work - ensure that any scheduled work has run to completion.
- *
- * Forces execution of the kernel-global workqueue and blocks until its
- * completion.
- *
- * Think twice before calling this function!  It's very easy to get into
- * trouble if you don't take great care.  Either of the following situations
- * will lead to deadlock:
- *
- *	One of the work items currently on the workqueue needs to acquire
- *	a lock held by your code or its caller.
- *
- *	Your code is running in the context of a work routine.
+ * workqueue_congested - test whether a workqueue is congested
+ * @cpu: CPU in question
+ * @wq: target workqueue
  *
- * They will be detected by lockdep when they occur, but the first might not
- * occur very often.  It depends on what work items are on the workqueue and
- * what locks they need, which you have no control over.
+ * Test whether @wq's cpu workqueue for @cpu is congested.  There is
+ * no synchronization around this function and the test result is
+ * unreliable and only useful as advisory hints or for debugging.
  *
- * In most situations flushing the entire workqueue is overkill; you merely
- * need to know that a particular work item isn't queued and isn't running.
- * In such cases you should use cancel_delayed_work_sync() or
- * cancel_work_sync() instead.
+ * RETURNS:
+ * %true if congested, %false otherwise.
  */
-void flush_scheduled_work(void)
+bool workqueue_congested(unsigned int cpu, struct workqueue_struct *wq)
 {
-	flush_workqueue(keventd_wq);
+	struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
+
+	return !list_empty(&cwq->delayed_works);
 }
-EXPORT_SYMBOL(flush_scheduled_work);
+EXPORT_SYMBOL_GPL(workqueue_congested);
 
 /**
- * execute_in_process_context - reliably execute the routine with user context
- * @fn:		the function to execute
- * @ew:		guaranteed storage for the execute work structure (must
- *		be available when the work executes)
+ * work_cpu - return the last known associated cpu for @work
+ * @work: the work of interest
  *
- * Executes the function immediately if process context is available,
- * otherwise schedules the function for delayed execution.
- *
- * Returns:	0 - function was executed
- *		1 - function was scheduled for execution
+ * RETURNS:
+ * CPU number if @work was ever queued.  WORK_CPU_NONE otherwise.
  */
-int execute_in_process_context(work_func_t fn, struct execute_work *ew)
+unsigned int work_cpu(struct work_struct *work)
 {
-	if (!in_interrupt()) {
-		fn(&ew->work);
-		return 0;
-	}
-
-	INIT_WORK(&ew->work, fn);
-	schedule_work(&ew->work);
+	struct global_cwq *gcwq = get_work_gcwq(work);
 
-	return 1;
+	return gcwq ? gcwq->cpu : WORK_CPU_NONE;
 }
-EXPORT_SYMBOL_GPL(execute_in_process_context);
+EXPORT_SYMBOL_GPL(work_cpu);
 
-int keventd_up(void)
+/**
+ * work_busy - test whether a work is currently pending or running
+ * @work: the work to be tested
+ *
+ * Test whether @work is currently pending or running.  There is no
+ * synchronization around this function and the test result is
+ * unreliable and only useful as advisory hints or for debugging.
+ * Especially for reentrant wqs, the pending state might hide the
+ * running state.
+ *
+ * RETURNS:
+ * OR'd bitmask of WORK_BUSY_* bits.
+ */
+unsigned int work_busy(struct work_struct *work)
 {
-	return keventd_wq != NULL;
-}
+	struct global_cwq *gcwq = get_work_gcwq(work);
+	unsigned long flags;
+	unsigned int ret = 0;
 
-int current_is_keventd(void)
-{
-	struct cpu_workqueue_struct *cwq;
-	int cpu = raw_smp_processor_id(); /* preempt-safe: keventd is per-cpu */
-	int ret = 0;
+	if (!gcwq)
+		return false;
 
-	BUG_ON(!keventd_wq);
+	spin_lock_irqsave(&gcwq->lock, flags);
 
-	cwq = per_cpu_ptr(keventd_wq->cpu_wq, cpu);
-	if (current == cwq->thread)
-		ret = 1;
+	if (work_pending(work))
+		ret |= WORK_BUSY_PENDING;
+	if (find_worker_executing_work(gcwq, work))
+		ret |= WORK_BUSY_RUNNING;
 
-	return ret;
+	spin_unlock_irqrestore(&gcwq->lock, flags);
 
+	return ret;
 }
+EXPORT_SYMBOL_GPL(work_busy);
 
-static struct cpu_workqueue_struct *
-init_cpu_workqueue(struct workqueue_struct *wq, int cpu)
-{
-	struct cpu_workqueue_struct *cwq = per_cpu_ptr(wq->cpu_wq, cpu);
+/*
+ * CPU hotplug.
+ *
+ * There are two challenges in supporting CPU hotplug.  Firstly, there
+ * are a lot of assumptions on strong associations among work, cwq and
+ * gcwq which make migrating pending and scheduled works very
+ * difficult to implement without impacting hot paths.  Secondly,
+ * gcwqs serve mix of short, long and very long running works making
+ * blocked draining impractical.
+ *
+ * This is solved by allowing a gcwq to be detached from CPU, running
+ * it with unbound (rogue) workers and allowing it to be reattached
+ * later if the cpu comes back online.  A separate thread is created
+ * to govern a gcwq in such state and is called the trustee of the
+ * gcwq.
+ *
+ * Trustee states and their descriptions.
+ *
+ * START	Command state used on startup.  On CPU_DOWN_PREPARE, a
+ *		new trustee is started with this state.
+ *
+ * IN_CHARGE	Once started, trustee will enter this state after
+ *		assuming the manager role and making all existing
+ *		workers rogue.  DOWN_PREPARE waits for trustee to
+ *		enter this state.  After reaching IN_CHARGE, trustee
+ *		tries to execute the pending worklist until it's empty
+ *		and the state is set to BUTCHER, or the state is set
+ *		to RELEASE.
+ *
+ * BUTCHER	Command state which is set by the cpu callback after
+ *		the cpu has went down.  Once this state is set trustee
+ *		knows that there will be no new works on the worklist
+ *		and once the worklist is empty it can proceed to
+ *		killing idle workers.
+ *
+ * RELEASE	Command state which is set by the cpu callback if the
+ *		cpu down has been canceled or it has come online
+ *		again.  After recognizing this state, trustee stops
+ *		trying to drain or butcher and clears ROGUE, rebinds
+ *		all remaining workers back to the cpu and releases
+ *		manager role.
+ *
+ * DONE		Trustee will enter this state after BUTCHER or RELEASE
+ *		is complete.
+ *
+ *          trustee                 CPU                draining
+ *         took over                down               complete
+ * START -----------> IN_CHARGE -----------> BUTCHER -----------> DONE
+ *                        |                     |                  ^
+ *                        | CPU is back online  v   return workers |
+ *                         ----------------> RELEASE --------------
+ */
 
-	cwq->wq = wq;
-	spin_lock_init(&cwq->lock);
-	INIT_LIST_HEAD(&cwq->worklist);
-	init_waitqueue_head(&cwq->more_work);
+/**
+ * trustee_wait_event_timeout - timed event wait for trustee
+ * @cond: condition to wait for
+ * @timeout: timeout in jiffies
+ *
+ * wait_event_timeout() for trustee to use.  Handles locking and
+ * checks for RELEASE request.
+ *
+ * CONTEXT:
+ * spin_lock_irq(gcwq->lock) which may be released and regrabbed
+ * multiple times.  To be used by trustee.
+ *
+ * RETURNS:
+ * Positive indicating left time if @cond is satisfied, 0 if timed
+ * out, -1 if canceled.
+ */
+#define trustee_wait_event_timeout(cond, timeout) ({			\
+	long __ret = (timeout);						\
+	while (!((cond) || (gcwq->trustee_state == TRUSTEE_RELEASE)) &&	\
+	       __ret) {							\
+		spin_unlock_irq(&gcwq->lock);				\
+		__wait_event_timeout(gcwq->trustee_wait, (cond) ||	\
+			(gcwq->trustee_state == TRUSTEE_RELEASE),	\
+			__ret);						\
+		spin_lock_irq(&gcwq->lock);				\
+	}								\
+	gcwq->trustee_state == TRUSTEE_RELEASE ? -1 : (__ret);		\
+})
 
-	return cwq;
-}
+/**
+ * trustee_wait_event - event wait for trustee
+ * @cond: condition to wait for
+ *
+ * wait_event() for trustee to use.  Automatically handles locking and
+ * checks for CANCEL request.
+ *
+ * CONTEXT:
+ * spin_lock_irq(gcwq->lock) which may be released and regrabbed
+ * multiple times.  To be used by trustee.
+ *
+ * RETURNS:
+ * 0 if @cond is satisfied, -1 if canceled.
+ */
+#define trustee_wait_event(cond) ({					\
+	long __ret1;							\
+	__ret1 = trustee_wait_event_timeout(cond, MAX_SCHEDULE_TIMEOUT);\
+	__ret1 < 0 ? -1 : 0;						\
+})
 
-static int create_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu)
+static int __cpuinit trustee_thread(void *__gcwq)
 {
-	struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
-	struct workqueue_struct *wq = cwq->wq;
-	const char *fmt = is_wq_single_threaded(wq) ? "%s" : "%s/%d";
-	struct task_struct *p;
+	struct global_cwq *gcwq = __gcwq;
+	struct worker *worker;
+	struct work_struct *work;
+	struct hlist_node *pos;
+	long rc;
+	int i;
 
-	p = kthread_create(worker_thread, cwq, fmt, wq->name, cpu);
+	BUG_ON(gcwq->cpu != smp_processor_id());
+
+	spin_lock_irq(&gcwq->lock);
 	/*
-	 * Nobody can add the work_struct to this cwq,
-	 *	if (caller is __create_workqueue)
-	 *		nobody should see this wq
-	 *	else // caller is CPU_UP_PREPARE
-	 *		cpu is not on cpu_online_map
-	 * so we can abort safely.
+	 * Claim the manager position and make all workers rogue.
+	 * Trustee must be bound to the target cpu and can't be
+	 * cancelled.
 	 */
-	if (IS_ERR(p))
-		return PTR_ERR(p);
-	if (cwq->wq->rt)
-		sched_setscheduler_nocheck(p, SCHED_FIFO, &param);
-	cwq->thread = p;
+	BUG_ON(gcwq->cpu != smp_processor_id());
+	rc = trustee_wait_event(!(gcwq->flags & GCWQ_MANAGING_WORKERS));
+	BUG_ON(rc < 0);
 
-	trace_workqueue_creation(cwq->thread, cpu);
+	gcwq->flags |= GCWQ_MANAGING_WORKERS;
 
-	return 0;
-}
+	list_for_each_entry(worker, &gcwq->idle_list, entry)
+		worker->flags |= WORKER_ROGUE;
 
-static void start_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu)
-{
-	struct task_struct *p = cwq->thread;
+	for_each_busy_worker(worker, i, pos, gcwq)
+		worker->flags |= WORKER_ROGUE;
 
-	if (p != NULL) {
-		if (cpu >= 0)
-			kthread_bind(p, cpu);
-		wake_up_process(p);
-	}
-}
+	/*
+	 * Call schedule() so that we cross rq->lock and thus can
+	 * guarantee sched callbacks see the rogue flag.  This is
+	 * necessary as scheduler callbacks may be invoked from other
+	 * cpus.
+	 */
+	spin_unlock_irq(&gcwq->lock);
+	schedule();
+	spin_lock_irq(&gcwq->lock);
 
-struct workqueue_struct *__create_workqueue_key(const char *name,
-						int singlethread,
-						int freezeable,
-						int rt,
-						struct lock_class_key *key,
-						const char *lock_name)
-{
-	struct workqueue_struct *wq;
-	struct cpu_workqueue_struct *cwq;
-	int err = 0, cpu;
+	/*
+	 * Sched callbacks are disabled now.  Zap nr_running.  After
+	 * this, nr_running stays zero and need_more_worker() and
+	 * keep_working() are always true as long as the worklist is
+	 * not empty.
+	 */
+	atomic_set(get_gcwq_nr_running(gcwq->cpu), 0);
 
-	wq = kzalloc(sizeof(*wq), GFP_KERNEL);
-	if (!wq)
-		return NULL;
+	spin_unlock_irq(&gcwq->lock);
+	del_timer_sync(&gcwq->idle_timer);
+	spin_lock_irq(&gcwq->lock);
 
-	wq->cpu_wq = alloc_percpu(struct cpu_workqueue_struct);
-	if (!wq->cpu_wq) {
-		kfree(wq);
-		return NULL;
-	}
+	/*
+	 * We're now in charge.  Notify and proceed to drain.  We need
+	 * to keep the gcwq running during the whole CPU down
+	 * procedure as other cpu hotunplug callbacks may need to
+	 * flush currently running tasks.
+	 */
+	gcwq->trustee_state = TRUSTEE_IN_CHARGE;
+	wake_up_all(&gcwq->trustee_wait);
 
-	wq->name = name;
-	lockdep_init_map(&wq->lockdep_map, lock_name, key, 0);
-	wq->singlethread = singlethread;
-	wq->freezeable = freezeable;
-	wq->rt = rt;
-	INIT_LIST_HEAD(&wq->list);
+	/*
+	 * The original cpu is in the process of dying and may go away
+	 * anytime now.  When that happens, we and all workers would
+	 * be migrated to other cpus.  Try draining any left work.  We
+	 * want to get it over with ASAP - spam rescuers, wake up as
+	 * many idlers as necessary and create new ones till the
+	 * worklist is empty.  Note that if the gcwq is frozen, there
+	 * may be frozen works in freezeable cwqs.  Don't declare
+	 * completion while frozen.
+	 */
+	while (gcwq->nr_workers != gcwq->nr_idle ||
+	       gcwq->flags & GCWQ_FREEZING ||
+	       gcwq->trustee_state == TRUSTEE_IN_CHARGE) {
+		int nr_works = 0;
+
+		list_for_each_entry(work, &gcwq->worklist, entry) {
+			send_mayday(work);
+			nr_works++;
+		}
 
-	if (singlethread) {
-		cwq = init_cpu_workqueue(wq, singlethread_cpu);
-		err = create_workqueue_thread(cwq, singlethread_cpu);
-		start_workqueue_thread(cwq, -1);
-	} else {
-		cpu_maps_update_begin();
-		/*
-		 * We must place this wq on list even if the code below fails.
-		 * cpu_down(cpu) can remove cpu from cpu_populated_map before
-		 * destroy_workqueue() takes the lock, in that case we leak
-		 * cwq[cpu]->thread.
-		 */
-		spin_lock(&workqueue_lock);
-		list_add(&wq->list, &workqueues);
-		spin_unlock(&workqueue_lock);
-		/*
-		 * We must initialize cwqs for each possible cpu even if we
-		 * are going to call destroy_workqueue() finally. Otherwise
-		 * cpu_up() can hit the uninitialized cwq once we drop the
-		 * lock.
-		 */
-		for_each_possible_cpu(cpu) {
-			cwq = init_cpu_workqueue(wq, cpu);
-			if (err || !cpu_online(cpu))
-				continue;
-			err = create_workqueue_thread(cwq, cpu);
-			start_workqueue_thread(cwq, cpu);
+		list_for_each_entry(worker, &gcwq->idle_list, entry) {
+			if (!nr_works--)
+				break;
+			wake_up_process(worker->task);
+		}
+
+		if (need_to_create_worker(gcwq)) {
+			spin_unlock_irq(&gcwq->lock);
+			worker = create_worker(gcwq, false);
+			spin_lock_irq(&gcwq->lock);
+			if (worker) {
+				worker->flags |= WORKER_ROGUE;
+				start_worker(worker);
+			}
 		}
-		cpu_maps_update_done();
-	}
 
-	if (err) {
-		destroy_workqueue(wq);
-		wq = NULL;
+		/* give a breather */
+		if (trustee_wait_event_timeout(false, TRUSTEE_COOLDOWN) < 0)
+			break;
 	}
-	return wq;
-}
-EXPORT_SYMBOL_GPL(__create_workqueue_key);
 
-static void cleanup_workqueue_thread(struct cpu_workqueue_struct *cwq)
-{
 	/*
-	 * Our caller is either destroy_workqueue() or CPU_POST_DEAD,
-	 * cpu_add_remove_lock protects cwq->thread.
+	 * Either all works have been scheduled and cpu is down, or
+	 * cpu down has already been canceled.  Wait for and butcher
+	 * all workers till we're canceled.
 	 */
-	if (cwq->thread == NULL)
-		return;
-
-	lock_map_acquire(&cwq->wq->lockdep_map);
-	lock_map_release(&cwq->wq->lockdep_map);
+	do {
+		rc = trustee_wait_event(!list_empty(&gcwq->idle_list));
+		while (!list_empty(&gcwq->idle_list))
+			destroy_worker(list_first_entry(&gcwq->idle_list,
+							struct worker, entry));
+	} while (gcwq->nr_workers && rc >= 0);
 
-	flush_cpu_workqueue(cwq);
 	/*
-	 * If the caller is CPU_POST_DEAD and cwq->worklist was not empty,
-	 * a concurrent flush_workqueue() can insert a barrier after us.
-	 * However, in that case run_workqueue() won't return and check
-	 * kthread_should_stop() until it flushes all work_struct's.
-	 * When ->worklist becomes empty it is safe to exit because no
-	 * more work_structs can be queued on this cwq: flush_workqueue
-	 * checks list_empty(), and a "normal" queue_work() can't use
-	 * a dead CPU.
+	 * At this point, either draining has completed and no worker
+	 * is left, or cpu down has been canceled or the cpu is being
+	 * brought back up.  There shouldn't be any idle one left.
+	 * Tell the remaining busy ones to rebind once it finishes the
+	 * currently scheduled works by scheduling the rebind_work.
 	 */
-	trace_workqueue_destruction(cwq->thread);
-	kthread_stop(cwq->thread);
-	cwq->thread = NULL;
+	WARN_ON(!list_empty(&gcwq->idle_list));
+
+	for_each_busy_worker(worker, i, pos, gcwq) {
+		struct work_struct *rebind_work = &worker->rebind_work;
+
+		/*
+		 * Rebind_work may race with future cpu hotplug
+		 * operations.  Use a separate flag to mark that
+		 * rebinding is scheduled.
+		 */
+		worker->flags |= WORKER_REBIND;
+		worker->flags &= ~WORKER_ROGUE;
+
+		/* queue rebind_work, wq doesn't matter, use the default one */
+		if (test_and_set_bit(WORK_STRUCT_PENDING_BIT,
+				     work_data_bits(rebind_work)))
+			continue;
+
+		debug_work_activate(rebind_work);
+		insert_work(get_cwq(gcwq->cpu, system_wq), rebind_work,
+			    worker->scheduled.next,
+			    work_color_to_flags(WORK_NO_COLOR));
+	}
+
+	/* relinquish manager role */
+	gcwq->flags &= ~GCWQ_MANAGING_WORKERS;
+
+	/* notify completion */
+	gcwq->trustee = NULL;
+	gcwq->trustee_state = TRUSTEE_DONE;
+	wake_up_all(&gcwq->trustee_wait);
+	spin_unlock_irq(&gcwq->lock);
+	return 0;
 }
 
 /**
- * destroy_workqueue - safely terminate a workqueue
- * @wq: target workqueue
+ * wait_trustee_state - wait for trustee to enter the specified state
+ * @gcwq: gcwq the trustee of interest belongs to
+ * @state: target state to wait for
  *
- * Safely destroy a workqueue. All work currently pending will be done first.
+ * Wait for the trustee to reach @state.  DONE is already matched.
+ *
+ * CONTEXT:
+ * spin_lock_irq(gcwq->lock) which may be released and regrabbed
+ * multiple times.  To be used by cpu_callback.
  */
-void destroy_workqueue(struct workqueue_struct *wq)
+static void __cpuinit wait_trustee_state(struct global_cwq *gcwq, int state)
 {
-	const struct cpumask *cpu_map = wq_cpu_map(wq);
-	int cpu;
-
-	cpu_maps_update_begin();
-	spin_lock(&workqueue_lock);
-	list_del(&wq->list);
-	spin_unlock(&workqueue_lock);
-
-	for_each_cpu(cpu, cpu_map)
-		cleanup_workqueue_thread(per_cpu_ptr(wq->cpu_wq, cpu));
- 	cpu_maps_update_done();
-
-	free_percpu(wq->cpu_wq);
-	kfree(wq);
+	if (!(gcwq->trustee_state == state ||
+	      gcwq->trustee_state == TRUSTEE_DONE)) {
+		spin_unlock_irq(&gcwq->lock);
+		__wait_event(gcwq->trustee_wait,
+			     gcwq->trustee_state == state ||
+			     gcwq->trustee_state == TRUSTEE_DONE);
+		spin_lock_irq(&gcwq->lock);
+	}
 }
-EXPORT_SYMBOL_GPL(destroy_workqueue);
 
 static int __devinit workqueue_cpu_callback(struct notifier_block *nfb,
 						unsigned long action,
 						void *hcpu)
 {
 	unsigned int cpu = (unsigned long)hcpu;
-	struct cpu_workqueue_struct *cwq;
-	struct workqueue_struct *wq;
-	int err = 0;
+	struct global_cwq *gcwq = get_gcwq(cpu);
+	struct task_struct *new_trustee = NULL;
+	struct worker *uninitialized_var(new_worker);
+	unsigned long flags;
 
 	action &= ~CPU_TASKS_FROZEN;
 
 	switch (action) {
+	case CPU_DOWN_PREPARE:
+		new_trustee = kthread_create(trustee_thread, gcwq,
+					     "workqueue_trustee/%d\n", cpu);
+		if (IS_ERR(new_trustee))
+			return notifier_from_errno(PTR_ERR(new_trustee));
+		kthread_bind(new_trustee, cpu);
+		/* fall through */
 	case CPU_UP_PREPARE:
-		cpumask_set_cpu(cpu, cpu_populated_map);
-	}
-undo:
-	list_for_each_entry(wq, &workqueues, list) {
-		cwq = per_cpu_ptr(wq->cpu_wq, cpu);
-
-		switch (action) {
-		case CPU_UP_PREPARE:
-			err = create_workqueue_thread(cwq, cpu);
-			if (!err)
-				break;
-			printk(KERN_ERR "workqueue [%s] for %i failed\n",
-				wq->name, cpu);
-			action = CPU_UP_CANCELED;
-			err = -ENOMEM;
-			goto undo;
-
-		case CPU_ONLINE:
-			start_workqueue_thread(cwq, cpu);
-			break;
-
-		case CPU_UP_CANCELED:
-			start_workqueue_thread(cwq, -1);
-		case CPU_POST_DEAD:
-			cleanup_workqueue_thread(cwq);
-			break;
+		BUG_ON(gcwq->first_idle);
+		new_worker = create_worker(gcwq, false);
+		if (!new_worker) {
+			if (new_trustee)
+				kthread_stop(new_trustee);
+			return NOTIFY_BAD;
 		}
 	}
 
+	/* some are called w/ irq disabled, don't disturb irq status */
+	spin_lock_irqsave(&gcwq->lock, flags);
+
 	switch (action) {
-	case CPU_UP_CANCELED:
+	case CPU_DOWN_PREPARE:
+		/* initialize trustee and tell it to acquire the gcwq */
+		BUG_ON(gcwq->trustee || gcwq->trustee_state != TRUSTEE_DONE);
+		gcwq->trustee = new_trustee;
+		gcwq->trustee_state = TRUSTEE_START;
+		wake_up_process(gcwq->trustee);
+		wait_trustee_state(gcwq, TRUSTEE_IN_CHARGE);
+		/* fall through */
+	case CPU_UP_PREPARE:
+		BUG_ON(gcwq->first_idle);
+		gcwq->first_idle = new_worker;
+		break;
+
+	case CPU_DYING:
+		/*
+		 * Before this, the trustee and all workers except for
+		 * the ones which are still executing works from
+		 * before the last CPU down must be on the cpu.  After
+		 * this, they'll all be diasporas.
+		 */
+		gcwq->flags |= GCWQ_DISASSOCIATED;
+		break;
+
 	case CPU_POST_DEAD:
-		cpumask_clear_cpu(cpu, cpu_populated_map);
+		gcwq->trustee_state = TRUSTEE_BUTCHER;
+		/* fall through */
+	case CPU_UP_CANCELED:
+		destroy_worker(gcwq->first_idle);
+		gcwq->first_idle = NULL;
+		break;
+
+	case CPU_DOWN_FAILED:
+	case CPU_ONLINE:
+		gcwq->flags &= ~GCWQ_DISASSOCIATED;
+		if (gcwq->trustee_state != TRUSTEE_DONE) {
+			gcwq->trustee_state = TRUSTEE_RELEASE;
+			wake_up_process(gcwq->trustee);
+			wait_trustee_state(gcwq, TRUSTEE_DONE);
+		}
+
+		/*
+		 * Trustee is done and there might be no worker left.
+		 * Put the first_idle in and request a real manager to
+		 * take a look.
+		 */
+		spin_unlock_irq(&gcwq->lock);
+		kthread_bind(gcwq->first_idle->task, cpu);
+		spin_lock_irq(&gcwq->lock);
+		gcwq->flags |= GCWQ_MANAGE_WORKERS;
+		start_worker(gcwq->first_idle);
+		gcwq->first_idle = NULL;
+		break;
 	}
 
-	return notifier_from_errno(err);
+	spin_unlock_irqrestore(&gcwq->lock, flags);
+
+	return notifier_from_errno(0);
 }
 
 #ifdef CONFIG_SMP
@@ -1216,14 +3381,199 @@ long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg)
 EXPORT_SYMBOL_GPL(work_on_cpu);
 #endif /* CONFIG_SMP */
 
-void __init init_workqueues(void)
+#ifdef CONFIG_FREEZER
+
+/**
+ * freeze_workqueues_begin - begin freezing workqueues
+ *
+ * Start freezing workqueues.  After this function returns, all
+ * freezeable workqueues will queue new works to their frozen_works
+ * list instead of gcwq->worklist.
+ *
+ * CONTEXT:
+ * Grabs and releases workqueue_lock and gcwq->lock's.
+ */
+void freeze_workqueues_begin(void)
+{
+	unsigned int cpu;
+
+	spin_lock(&workqueue_lock);
+
+	BUG_ON(workqueue_freezing);
+	workqueue_freezing = true;
+
+	for_each_gcwq_cpu(cpu) {
+		struct global_cwq *gcwq = get_gcwq(cpu);
+		struct workqueue_struct *wq;
+
+		spin_lock_irq(&gcwq->lock);
+
+		BUG_ON(gcwq->flags & GCWQ_FREEZING);
+		gcwq->flags |= GCWQ_FREEZING;
+
+		list_for_each_entry(wq, &workqueues, list) {
+			struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
+
+			if (cwq && wq->flags & WQ_FREEZEABLE)
+				cwq->max_active = 0;
+		}
+
+		spin_unlock_irq(&gcwq->lock);
+	}
+
+	spin_unlock(&workqueue_lock);
+}
+
+/**
+ * freeze_workqueues_busy - are freezeable workqueues still busy?
+ *
+ * Check whether freezing is complete.  This function must be called
+ * between freeze_workqueues_begin() and thaw_workqueues().
+ *
+ * CONTEXT:
+ * Grabs and releases workqueue_lock.
+ *
+ * RETURNS:
+ * %true if some freezeable workqueues are still busy.  %false if
+ * freezing is complete.
+ */
+bool freeze_workqueues_busy(void)
+{
+	unsigned int cpu;
+	bool busy = false;
+
+	spin_lock(&workqueue_lock);
+
+	BUG_ON(!workqueue_freezing);
+
+	for_each_gcwq_cpu(cpu) {
+		struct workqueue_struct *wq;
+		/*
+		 * nr_active is monotonically decreasing.  It's safe
+		 * to peek without lock.
+		 */
+		list_for_each_entry(wq, &workqueues, list) {
+			struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
+
+			if (!cwq || !(wq->flags & WQ_FREEZEABLE))
+				continue;
+
+			BUG_ON(cwq->nr_active < 0);
+			if (cwq->nr_active) {
+				busy = true;
+				goto out_unlock;
+			}
+		}
+	}
+out_unlock:
+	spin_unlock(&workqueue_lock);
+	return busy;
+}
+
+/**
+ * thaw_workqueues - thaw workqueues
+ *
+ * Thaw workqueues.  Normal queueing is restored and all collected
+ * frozen works are transferred to their respective gcwq worklists.
+ *
+ * CONTEXT:
+ * Grabs and releases workqueue_lock and gcwq->lock's.
+ */
+void thaw_workqueues(void)
+{
+	unsigned int cpu;
+
+	spin_lock(&workqueue_lock);
+
+	if (!workqueue_freezing)
+		goto out_unlock;
+
+	for_each_gcwq_cpu(cpu) {
+		struct global_cwq *gcwq = get_gcwq(cpu);
+		struct workqueue_struct *wq;
+
+		spin_lock_irq(&gcwq->lock);
+
+		BUG_ON(!(gcwq->flags & GCWQ_FREEZING));
+		gcwq->flags &= ~GCWQ_FREEZING;
+
+		list_for_each_entry(wq, &workqueues, list) {
+			struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
+
+			if (!cwq || !(wq->flags & WQ_FREEZEABLE))
+				continue;
+
+			/* restore max_active and repopulate worklist */
+			cwq->max_active = wq->saved_max_active;
+
+			while (!list_empty(&cwq->delayed_works) &&
+			       cwq->nr_active < cwq->max_active)
+				cwq_activate_first_delayed(cwq);
+		}
+
+		wake_up_worker(gcwq);
+
+		spin_unlock_irq(&gcwq->lock);
+	}
+
+	workqueue_freezing = false;
+out_unlock:
+	spin_unlock(&workqueue_lock);
+}
+#endif /* CONFIG_FREEZER */
+
+static int __init init_workqueues(void)
 {
-	alloc_cpumask_var(&cpu_populated_map, GFP_KERNEL);
+	unsigned int cpu;
+	int i;
+
+	hotcpu_notifier(workqueue_cpu_callback, CPU_PRI_WORKQUEUE);
+
+	/* initialize gcwqs */
+	for_each_gcwq_cpu(cpu) {
+		struct global_cwq *gcwq = get_gcwq(cpu);
+
+		spin_lock_init(&gcwq->lock);
+		INIT_LIST_HEAD(&gcwq->worklist);
+		gcwq->cpu = cpu;
+		if (cpu == WORK_CPU_UNBOUND)
+			gcwq->flags |= GCWQ_DISASSOCIATED;
+
+		INIT_LIST_HEAD(&gcwq->idle_list);
+		for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++)
+			INIT_HLIST_HEAD(&gcwq->busy_hash[i]);
+
+		init_timer_deferrable(&gcwq->idle_timer);
+		gcwq->idle_timer.function = idle_worker_timeout;
+		gcwq->idle_timer.data = (unsigned long)gcwq;
 
-	cpumask_copy(cpu_populated_map, cpu_online_mask);
-	singlethread_cpu = cpumask_first(cpu_possible_mask);
-	cpu_singlethread_map = cpumask_of(singlethread_cpu);
-	hotcpu_notifier(workqueue_cpu_callback, 0);
-	keventd_wq = create_workqueue("events");
-	BUG_ON(!keventd_wq);
+		setup_timer(&gcwq->mayday_timer, gcwq_mayday_timeout,
+			    (unsigned long)gcwq);
+
+		ida_init(&gcwq->worker_ida);
+
+		gcwq->trustee_state = TRUSTEE_DONE;
+		init_waitqueue_head(&gcwq->trustee_wait);
+	}
+
+	/* create the initial worker */
+	for_each_online_gcwq_cpu(cpu) {
+		struct global_cwq *gcwq = get_gcwq(cpu);
+		struct worker *worker;
+
+		worker = create_worker(gcwq, true);
+		BUG_ON(!worker);
+		spin_lock_irq(&gcwq->lock);
+		start_worker(worker);
+		spin_unlock_irq(&gcwq->lock);
+	}
+
+	system_wq = alloc_workqueue("events", 0, 0);
+	system_long_wq = alloc_workqueue("events_long", 0, 0);
+	system_nrt_wq = alloc_workqueue("events_nrt", WQ_NON_REENTRANT, 0);
+	system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND,
+					    WQ_UNBOUND_MAX_ACTIVE);
+	BUG_ON(!system_wq || !system_long_wq || !system_nrt_wq);
+	return 0;
 }
+early_initcall(init_workqueues);

kernel/workqueue_sched.h

@@ -4,13 +4,6 @@
  * Scheduler hooks for concurrency managed workqueue.  Only to be
  * included from sched.c and workqueue.c.
  */
-static inline void wq_worker_waking_up(struct task_struct *task,
-				       unsigned int cpu)
-{
-}
-
-static inline struct task_struct *wq_worker_sleeping(struct task_struct *task,
-						     unsigned int cpu)
-{
-	return NULL;
-}
+void wq_worker_waking_up(struct task_struct *task, unsigned int cpu);
+struct task_struct *wq_worker_sleeping(struct task_struct *task,
+				       unsigned int cpu);