Merge remote-tracking branch 'gregkh-driver-core/driver-core-next' into arm/exynos

Documentation/ABI/testing/sysfs-devices-deferred_probe

@@ -0,0 +1,12 @@
+What:		/sys/devices/.../deferred_probe
+Date:		August 2016
+Contact:	Ben Hutchings <ben.hutchings@codethink.co.uk>
+Description:
+		The /sys/devices/.../deferred_probe attribute is
+		present for all devices.  If a driver detects during
+		probing a device that a related device is not yet
+		ready, it may defer probing of the first device.  The
+		kernel will retry probing the first device after any
+		other device is successfully probed.  This attribute
+		reads as 1 if probing of this device is currently
+		deferred, or 0 otherwise.

arch/x86/kernel/cpu/intel_cacheinfo.c

@@ -934,6 +934,8 @@ static int __populate_cache_leaves(unsigned int cpu)
 		ci_leaf_init(this_leaf++, &id4_regs);
 		__cache_cpumap_setup(cpu, idx, &id4_regs);
 	}
+	this_cpu_ci->cpu_map_populated = true;
+
 	return 0;
 }
 

drivers/base/Kconfig

@@ -224,6 +224,8 @@ config DEBUG_TEST_DRIVER_REMOVE
 	  unusable. You should say N here unless you are explicitly looking to
 	  test this functionality.
 
+source "drivers/base/test/Kconfig"
+
 config SYS_HYPERVISOR
 	bool
 	default n

drivers/base/Makefile

@@ -24,5 +24,7 @@ obj-$(CONFIG_PINCTRL) += pinctrl.o
 obj-$(CONFIG_DEV_COREDUMP) += devcoredump.o
 obj-$(CONFIG_GENERIC_MSI_IRQ_DOMAIN) += platform-msi.o
 
+obj-y			+= test/
+
 ccflags-$(CONFIG_DEBUG_DRIVER) := -DDEBUG
 

drivers/base/base.h

@@ -107,6 +107,9 @@ extern void bus_remove_device(struct device *dev);
 
 extern int bus_add_driver(struct device_driver *drv);
 extern void bus_remove_driver(struct device_driver *drv);
+extern void device_release_driver_internal(struct device *dev,
+					   struct device_driver *drv,
+					   struct device *parent);
 
 extern void driver_detach(struct device_driver *drv);
 extern int driver_probe_device(struct device_driver *drv, struct device *dev);
@@ -138,6 +141,8 @@ extern void device_unblock_probing(void);
 extern struct kset *devices_kset;
 extern void devices_kset_move_last(struct device *dev);
 
+extern struct device_attribute dev_attr_deferred_probe;
+
 #if defined(CONFIG_MODULES) && defined(CONFIG_SYSFS)
 extern void module_add_driver(struct module *mod, struct device_driver *drv);
 extern void module_remove_driver(struct device_driver *drv);
@@ -152,3 +157,13 @@ extern int devtmpfs_init(void);
 #else
 static inline int devtmpfs_init(void) { return 0; }
 #endif
+
+/* Device links support */
+extern int device_links_read_lock(void);
+extern void device_links_read_unlock(int idx);
+extern int device_links_check_suppliers(struct device *dev);
+extern void device_links_driver_bound(struct device *dev);
+extern void device_links_driver_cleanup(struct device *dev);
+extern void device_links_no_driver(struct device *dev);
+extern bool device_links_busy(struct device *dev);
+extern void device_links_unbind_consumers(struct device *dev);

drivers/base/cacheinfo.c

@@ -16,6 +16,9 @@
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/acpi.h>
 #include <linux/bitops.h>
 #include <linux/cacheinfo.h>
 #include <linux/compiler.h>
@@ -85,7 +88,120 @@ static inline bool cache_leaves_are_shared(struct cacheinfo *this_leaf,
 {
 	return sib_leaf->of_node == this_leaf->of_node;
 }
+
+/* OF properties to query for a given cache type */
+struct cache_type_info {
+	const char *size_prop;
+	const char *line_size_props[2];
+	const char *nr_sets_prop;
+};
+
+static const struct cache_type_info cache_type_info[] = {
+	{
+		.size_prop       = "cache-size",
+		.line_size_props = { "cache-line-size",
+				     "cache-block-size", },
+		.nr_sets_prop    = "cache-sets",
+	}, {
+		.size_prop       = "i-cache-size",
+		.line_size_props = { "i-cache-line-size",
+				     "i-cache-block-size", },
+		.nr_sets_prop    = "i-cache-sets",
+	}, {
+		.size_prop       = "d-cache-size",
+		.line_size_props = { "d-cache-line-size",
+				     "d-cache-block-size", },
+		.nr_sets_prop    = "d-cache-sets",
+	},
+};
+
+static inline int get_cacheinfo_idx(enum cache_type type)
+{
+	if (type == CACHE_TYPE_UNIFIED)
+		return 0;
+	return type;
+}
+
+static void cache_size(struct cacheinfo *this_leaf)
+{
+	const char *propname;
+	const __be32 *cache_size;
+	int ct_idx;
+
+	ct_idx = get_cacheinfo_idx(this_leaf->type);
+	propname = cache_type_info[ct_idx].size_prop;
+
+	cache_size = of_get_property(this_leaf->of_node, propname, NULL);
+	if (cache_size)
+		this_leaf->size = of_read_number(cache_size, 1);
+}
+
+/* not cache_line_size() because that's a macro in include/linux/cache.h */
+static void cache_get_line_size(struct cacheinfo *this_leaf)
+{
+	const __be32 *line_size;
+	int i, lim, ct_idx;
+
+	ct_idx = get_cacheinfo_idx(this_leaf->type);
+	lim = ARRAY_SIZE(cache_type_info[ct_idx].line_size_props);
+
+	for (i = 0; i < lim; i++) {
+		const char *propname;
+
+		propname = cache_type_info[ct_idx].line_size_props[i];
+		line_size = of_get_property(this_leaf->of_node, propname, NULL);
+		if (line_size)
+			break;
+	}
+
+	if (line_size)
+		this_leaf->coherency_line_size = of_read_number(line_size, 1);
+}
+
+static void cache_nr_sets(struct cacheinfo *this_leaf)
+{
+	const char *propname;
+	const __be32 *nr_sets;
+	int ct_idx;
+
+	ct_idx = get_cacheinfo_idx(this_leaf->type);
+	propname = cache_type_info[ct_idx].nr_sets_prop;
+
+	nr_sets = of_get_property(this_leaf->of_node, propname, NULL);
+	if (nr_sets)
+		this_leaf->number_of_sets = of_read_number(nr_sets, 1);
+}
+
+static void cache_associativity(struct cacheinfo *this_leaf)
+{
+	unsigned int line_size = this_leaf->coherency_line_size;
+	unsigned int nr_sets = this_leaf->number_of_sets;
+	unsigned int size = this_leaf->size;
+
+	/*
+	 * If the cache is fully associative, there is no need to
+	 * check the other properties.
+	 */
+	if (!(nr_sets == 1) && (nr_sets > 0 && size > 0 && line_size > 0))
+		this_leaf->ways_of_associativity = (size / nr_sets) / line_size;
+}
+
+static void cache_of_override_properties(unsigned int cpu)
+{
+	int index;
+	struct cacheinfo *this_leaf;
+	struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu);
+
+	for (index = 0; index < cache_leaves(cpu); index++) {
+		this_leaf = this_cpu_ci->info_list + index;
+		cache_size(this_leaf);
+		cache_get_line_size(this_leaf);
+		cache_nr_sets(this_leaf);
+		cache_associativity(this_leaf);
+	}
+}
 #else
+static void cache_of_override_properties(unsigned int cpu) { }
 static inline int cache_setup_of_node(unsigned int cpu) { return 0; }
 static inline bool cache_leaves_are_shared(struct cacheinfo *this_leaf,
 					   struct cacheinfo *sib_leaf)
@@ -104,9 +220,16 @@ static int cache_shared_cpu_map_setup(unsigned int cpu)
 	struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu);
 	struct cacheinfo *this_leaf, *sib_leaf;
 	unsigned int index;
-	int ret;
+	int ret = 0;
 
-	ret = cache_setup_of_node(cpu);
+	if (this_cpu_ci->cpu_map_populated)
+		return 0;
+
+	if (of_have_populated_dt())
+		ret = cache_setup_of_node(cpu);
+	else if (!acpi_disabled)
+		/* No cache property/hierarchy support yet in ACPI */
+		ret = -ENOTSUPP;
 	if (ret)
 		return ret;
 
@@ -161,6 +284,12 @@ static void cache_shared_cpu_map_remove(unsigned int cpu)
 	}
 }
 
+static void cache_override_properties(unsigned int cpu)
+{
+	if (of_have_populated_dt())
+		return cache_of_override_properties(cpu);
+}
+
 static void free_cache_attributes(unsigned int cpu)
 {
 	if (!per_cpu_cacheinfo(cpu))
@@ -203,10 +332,11 @@ static int detect_cache_attributes(unsigned int cpu)
 	 */
 	ret = cache_shared_cpu_map_setup(cpu);
 	if (ret) {
-		pr_warn("Unable to detect cache hierarchy from DT for CPU %d\n",
-			cpu);
+		pr_warn("Unable to detect cache hierarchy for CPU %d\n", cpu);
 		goto free_ci;
 	}
+
+	cache_override_properties(cpu);
 	return 0;
 
 free_ci:

drivers/base/core.c

@@ -44,6 +44,572 @@ static int __init sysfs_deprecated_setup(char *arg)
 early_param("sysfs.deprecated", sysfs_deprecated_setup);
 #endif
 
+/* Device links support. */
+
+#ifdef CONFIG_SRCU
+static DEFINE_MUTEX(device_links_lock);
+DEFINE_STATIC_SRCU(device_links_srcu);
+
+static inline void device_links_write_lock(void)
+{
+	mutex_lock(&device_links_lock);
+}
+
+static inline void device_links_write_unlock(void)
+{
+	mutex_unlock(&device_links_lock);
+}
+
+int device_links_read_lock(void)
+{
+	return srcu_read_lock(&device_links_srcu);
+}
+
+void device_links_read_unlock(int idx)
+{
+	srcu_read_unlock(&device_links_srcu, idx);
+}
+#else /* !CONFIG_SRCU */
+static DECLARE_RWSEM(device_links_lock);
+
+static inline void device_links_write_lock(void)
+{
+	down_write(&device_links_lock);
+}
+
+static inline void device_links_write_unlock(void)
+{
+	up_write(&device_links_lock);
+}
+
+int device_links_read_lock(void)
+{
+	down_read(&device_links_lock);
+	return 0;
+}
+
+void device_links_read_unlock(int not_used)
+{
+	up_read(&device_links_lock);
+}
+#endif /* !CONFIG_SRCU */
+
+/**
+ * device_is_dependent - Check if one device depends on another one
+ * @dev: Device to check dependencies for.
+ * @target: Device to check against.
+ *
+ * Check if @target depends on @dev or any device dependent on it (its child or
+ * its consumer etc).  Return 1 if that is the case or 0 otherwise.
+ */
+static int device_is_dependent(struct device *dev, void *target)
+{
+	struct device_link *link;
+	int ret;
+
+	if (WARN_ON(dev == target))
+		return 1;
+
+	ret = device_for_each_child(dev, target, device_is_dependent);
+	if (ret)
+		return ret;
+
+	list_for_each_entry(link, &dev->links.consumers, s_node) {
+		if (WARN_ON(link->consumer == target))
+			return 1;
+
+		ret = device_is_dependent(link->consumer, target);
+		if (ret)
+			break;
+	}
+	return ret;
+}
+
+static int device_reorder_to_tail(struct device *dev, void *not_used)
+{
+	struct device_link *link;
+
+	/*
+	 * Devices that have not been registered yet will be put to the ends
+	 * of the lists during the registration, so skip them here.
+	 */
+	if (device_is_registered(dev))
+		devices_kset_move_last(dev);
+
+	if (device_pm_initialized(dev))
+		device_pm_move_last(dev);
+
+	device_for_each_child(dev, NULL, device_reorder_to_tail);
+	list_for_each_entry(link, &dev->links.consumers, s_node)
+		device_reorder_to_tail(link->consumer, NULL);
+
+	return 0;
+}
+
+/**
+ * device_link_add - Create a link between two devices.
+ * @consumer: Consumer end of the link.
+ * @supplier: Supplier end of the link.
+ * @flags: Link flags.
+ *
+ * The caller is responsible for the proper synchronization of the link creation
+ * with runtime PM.  First, setting the DL_FLAG_PM_RUNTIME flag will cause the
+ * runtime PM framework to take the link into account.  Second, if the
+ * DL_FLAG_RPM_ACTIVE flag is set in addition to it, the supplier devices will
+ * be forced into the active metastate and reference-counted upon the creation
+ * of the link.  If DL_FLAG_PM_RUNTIME is not set, DL_FLAG_RPM_ACTIVE will be
+ * ignored.
+ *
+ * If the DL_FLAG_AUTOREMOVE is set, the link will be removed automatically
+ * when the consumer device driver unbinds from it.  The combination of both
+ * DL_FLAG_AUTOREMOVE and DL_FLAG_STATELESS set is invalid and will cause NULL
+ * to be returned.
+ *
+ * A side effect of the link creation is re-ordering of dpm_list and the
+ * devices_kset list by moving the consumer device and all devices depending
+ * on it to the ends of these lists (that does not happen to devices that have
+ * not been registered when this function is called).
+ *
+ * The supplier device is required to be registered when this function is called
+ * and NULL will be returned if that is not the case.  The consumer device need
+ * not be registerd, however.
+ */
+struct device_link *device_link_add(struct device *consumer,
+				    struct device *supplier, u32 flags)
+{
+	struct device_link *link;
+
+	if (!consumer || !supplier ||
+	    ((flags & DL_FLAG_STATELESS) && (flags & DL_FLAG_AUTOREMOVE)))
+		return NULL;
+
+	device_links_write_lock();
+	device_pm_lock();
+
+	/*
+	 * If the supplier has not been fully registered yet or there is a
+	 * reverse dependency between the consumer and the supplier already in
+	 * the graph, return NULL.
+	 */
+	if (!device_pm_initialized(supplier)
+	    || device_is_dependent(consumer, supplier)) {
+		link = NULL;
+		goto out;
+	}
+
+	list_for_each_entry(link, &supplier->links.consumers, s_node)
+		if (link->consumer == consumer)
+			goto out;
+
+	link = kzalloc(sizeof(*link), GFP_KERNEL);
+	if (!link)
+		goto out;
+
+	if (flags & DL_FLAG_PM_RUNTIME) {
+		if (flags & DL_FLAG_RPM_ACTIVE) {
+			if (pm_runtime_get_sync(supplier) < 0) {
+				pm_runtime_put_noidle(supplier);
+				kfree(link);
+				link = NULL;
+				goto out;
+			}
+			link->rpm_active = true;
+		}
+		pm_runtime_new_link(consumer);
+	}
+	get_device(supplier);
+	link->supplier = supplier;
+	INIT_LIST_HEAD(&link->s_node);
+	get_device(consumer);
+	link->consumer = consumer;
+	INIT_LIST_HEAD(&link->c_node);
+	link->flags = flags;
+
+	/* Deterine the initial link state. */
+	if (flags & DL_FLAG_STATELESS) {
+		link->status = DL_STATE_NONE;
+	} else {
+		switch (supplier->links.status) {
+		case DL_DEV_DRIVER_BOUND:
+			switch (consumer->links.status) {
+			case DL_DEV_PROBING:
+				/*
+				 * Balance the decrementation of the supplier's
+				 * runtime PM usage counter after consumer probe
+				 * in driver_probe_device().
+				 */
+				if (flags & DL_FLAG_PM_RUNTIME)
+					pm_runtime_get_sync(supplier);
+
+				link->status = DL_STATE_CONSUMER_PROBE;
+				break;
+			case DL_DEV_DRIVER_BOUND:
+				link->status = DL_STATE_ACTIVE;
+				break;
+			default:
+				link->status = DL_STATE_AVAILABLE;
+				break;
+			}
+			break;
+		case DL_DEV_UNBINDING:
+			link->status = DL_STATE_SUPPLIER_UNBIND;
+			break;
+		default:
+			link->status = DL_STATE_DORMANT;
+			break;
+		}
+	}
+
+	/*
+	 * Move the consumer and all of the devices depending on it to the end
+	 * of dpm_list and the devices_kset list.
+	 *
+	 * It is necessary to hold dpm_list locked throughout all that or else
+	 * we may end up suspending with a wrong ordering of it.
+	 */
+	device_reorder_to_tail(consumer, NULL);
+
+	list_add_tail_rcu(&link->s_node, &supplier->links.consumers);
+	list_add_tail_rcu(&link->c_node, &consumer->links.suppliers);
+
+	dev_info(consumer, "Linked as a consumer to %s\n", dev_name(supplier));
+
+ out:
+	device_pm_unlock();
+	device_links_write_unlock();
+	return link;
+}
+EXPORT_SYMBOL_GPL(device_link_add);
+
+static void device_link_free(struct device_link *link)
+{
+	put_device(link->consumer);
+	put_device(link->supplier);
+	kfree(link);
+}
+
+#ifdef CONFIG_SRCU
+static void __device_link_free_srcu(struct rcu_head *rhead)
+{
+	device_link_free(container_of(rhead, struct device_link, rcu_head));
+}
+
+static void __device_link_del(struct device_link *link)
+{
+	dev_info(link->consumer, "Dropping the link to %s\n",
+		 dev_name(link->supplier));
+
+	if (link->flags & DL_FLAG_PM_RUNTIME)
+		pm_runtime_drop_link(link->consumer);
+
+	list_del_rcu(&link->s_node);
+	list_del_rcu(&link->c_node);
+	call_srcu(&device_links_srcu, &link->rcu_head, __device_link_free_srcu);
+}
+#else /* !CONFIG_SRCU */
+static void __device_link_del(struct device_link *link)
+{
+	dev_info(link->consumer, "Dropping the link to %s\n",
+		 dev_name(link->supplier));
+
+	list_del(&link->s_node);
+	list_del(&link->c_node);
+	device_link_free(link);
+}
+#endif /* !CONFIG_SRCU */
+
+/**
+ * device_link_del - Delete a link between two devices.
+ * @link: Device link to delete.
+ *
+ * The caller must ensure proper synchronization of this function with runtime
+ * PM.
+ */
+void device_link_del(struct device_link *link)
+{
+	device_links_write_lock();
+	device_pm_lock();
+	__device_link_del(link);
+	device_pm_unlock();
+	device_links_write_unlock();
+}
+EXPORT_SYMBOL_GPL(device_link_del);
+
+static void device_links_missing_supplier(struct device *dev)
+{
+	struct device_link *link;
+
+	list_for_each_entry(link, &dev->links.suppliers, c_node)
+		if (link->status == DL_STATE_CONSUMER_PROBE)
+			WRITE_ONCE(link->status, DL_STATE_AVAILABLE);
+}
+
+/**
+ * device_links_check_suppliers - Check presence of supplier drivers.
+ * @dev: Consumer device.
+ *
+ * Check links from this device to any suppliers.  Walk the list of the device's
+ * links to suppliers and see if all of them are available.  If not, simply
+ * return -EPROBE_DEFER.
+ *
+ * We need to guarantee that the supplier will not go away after the check has
+ * been positive here.  It only can go away in __device_release_driver() and
+ * that function  checks the device's links to consumers.  This means we need to
+ * mark the link as "consumer probe in progress" to make the supplier removal
+ * wait for us to complete (or bad things may happen).
+ *
+ * Links with the DL_FLAG_STATELESS flag set are ignored.
+ */
+int device_links_check_suppliers(struct device *dev)
+{
+	struct device_link *link;
+	int ret = 0;
+
+	device_links_write_lock();
+
+	list_for_each_entry(link, &dev->links.suppliers, c_node) {
+		if (link->flags & DL_FLAG_STATELESS)
+			continue;
+
+		if (link->status != DL_STATE_AVAILABLE) {
+			device_links_missing_supplier(dev);
+			ret = -EPROBE_DEFER;
+			break;
+		}
+		WRITE_ONCE(link->status, DL_STATE_CONSUMER_PROBE);
+	}
+	dev->links.status = DL_DEV_PROBING;
+
+	device_links_write_unlock();
+	return ret;
+}
+
+/**
+ * device_links_driver_bound - Update device links after probing its driver.
+ * @dev: Device to update the links for.
+ *
+ * The probe has been successful, so update links from this device to any
+ * consumers by changing their status to "available".
+ *
+ * Also change the status of @dev's links to suppliers to "active".
+ *
+ * Links with the DL_FLAG_STATELESS flag set are ignored.
+ */
+void device_links_driver_bound(struct device *dev)
+{
+	struct device_link *link;
+
+	device_links_write_lock();
+
+	list_for_each_entry(link, &dev->links.consumers, s_node) {
+		if (link->flags & DL_FLAG_STATELESS)
+			continue;
+
+		WARN_ON(link->status != DL_STATE_DORMANT);
+		WRITE_ONCE(link->status, DL_STATE_AVAILABLE);
+	}
+
+	list_for_each_entry(link, &dev->links.suppliers, c_node) {
+		if (link->flags & DL_FLAG_STATELESS)
+			continue;
+
+		WARN_ON(link->status != DL_STATE_CONSUMER_PROBE);
+		WRITE_ONCE(link->status, DL_STATE_ACTIVE);
+	}
+
+	dev->links.status = DL_DEV_DRIVER_BOUND;
+
+	device_links_write_unlock();
+}
+
+/**
+ * __device_links_no_driver - Update links of a device without a driver.
+ * @dev: Device without a drvier.
+ *
+ * Delete all non-persistent links from this device to any suppliers.
+ *
+ * Persistent links stay around, but their status is changed to "available",
+ * unless they already are in the "supplier unbind in progress" state in which
+ * case they need not be updated.
+ *
+ * Links with the DL_FLAG_STATELESS flag set are ignored.
+ */
+static void __device_links_no_driver(struct device *dev)
+{
+	struct device_link *link, *ln;
+
+	list_for_each_entry_safe_reverse(link, ln, &dev->links.suppliers, c_node) {
+		if (link->flags & DL_FLAG_STATELESS)
+			continue;
+
+		if (link->flags & DL_FLAG_AUTOREMOVE)
+			__device_link_del(link);
+		else if (link->status != DL_STATE_SUPPLIER_UNBIND)
+			WRITE_ONCE(link->status, DL_STATE_AVAILABLE);
+	}
+
+	dev->links.status = DL_DEV_NO_DRIVER;
+}
+
+void device_links_no_driver(struct device *dev)
+{
+	device_links_write_lock();
+	__device_links_no_driver(dev);
+	device_links_write_unlock();
+}
+
+/**
+ * device_links_driver_cleanup - Update links after driver removal.
+ * @dev: Device whose driver has just gone away.
+ *
+ * Update links to consumers for @dev by changing their status to "dormant" and
+ * invoke %__device_links_no_driver() to update links to suppliers for it as
+ * appropriate.
+ *
+ * Links with the DL_FLAG_STATELESS flag set are ignored.
+ */
+void device_links_driver_cleanup(struct device *dev)
+{
+	struct device_link *link;
+
+	device_links_write_lock();
+
+	list_for_each_entry(link, &dev->links.consumers, s_node) {
+		if (link->flags & DL_FLAG_STATELESS)
+			continue;
+
+		WARN_ON(link->flags & DL_FLAG_AUTOREMOVE);
+		WARN_ON(link->status != DL_STATE_SUPPLIER_UNBIND);
+		WRITE_ONCE(link->status, DL_STATE_DORMANT);
+	}
+
+	__device_links_no_driver(dev);
+
+	device_links_write_unlock();
+}
+
+/**
+ * device_links_busy - Check if there are any busy links to consumers.
+ * @dev: Device to check.
+ *
+ * Check each consumer of the device and return 'true' if its link's status
+ * is one of "consumer probe" or "active" (meaning that the given consumer is
+ * probing right now or its driver is present).  Otherwise, change the link
+ * state to "supplier unbind" to prevent the consumer from being probed
+ * successfully going forward.
+ *
+ * Return 'false' if there are no probing or active consumers.
+ *
+ * Links with the DL_FLAG_STATELESS flag set are ignored.
+ */
+bool device_links_busy(struct device *dev)
+{
+	struct device_link *link;
+	bool ret = false;
+
+	device_links_write_lock();
+
+	list_for_each_entry(link, &dev->links.consumers, s_node) {
+		if (link->flags & DL_FLAG_STATELESS)
+			continue;
+
+		if (link->status == DL_STATE_CONSUMER_PROBE
+		    || link->status == DL_STATE_ACTIVE) {
+			ret = true;
+			break;
+		}
+		WRITE_ONCE(link->status, DL_STATE_SUPPLIER_UNBIND);
+	}
+
+	dev->links.status = DL_DEV_UNBINDING;
+
+	device_links_write_unlock();
+	return ret;
+}
+
+/**
+ * device_links_unbind_consumers - Force unbind consumers of the given device.
+ * @dev: Device to unbind the consumers of.
+ *
+ * Walk the list of links to consumers for @dev and if any of them is in the
+ * "consumer probe" state, wait for all device probes in progress to complete
+ * and start over.
+ *
+ * If that's not the case, change the status of the link to "supplier unbind"
+ * and check if the link was in the "active" state.  If so, force the consumer
+ * driver to unbind and start over (the consumer will not re-probe as we have
+ * changed the state of the link already).
+ *
+ * Links with the DL_FLAG_STATELESS flag set are ignored.
+ */
+void device_links_unbind_consumers(struct device *dev)
+{
+	struct device_link *link;
+
+ start:
+	device_links_write_lock();
+
+	list_for_each_entry(link, &dev->links.consumers, s_node) {
+		enum device_link_state status;
+
+		if (link->flags & DL_FLAG_STATELESS)
+			continue;
+
+		status = link->status;
+		if (status == DL_STATE_CONSUMER_PROBE) {
+			device_links_write_unlock();
+
+			wait_for_device_probe();
+			goto start;
+		}
+		WRITE_ONCE(link->status, DL_STATE_SUPPLIER_UNBIND);
+		if (status == DL_STATE_ACTIVE) {
+			struct device *consumer = link->consumer;
+
+			get_device(consumer);
+
+			device_links_write_unlock();
+
+			device_release_driver_internal(consumer, NULL,
+						       consumer->parent);
+			put_device(consumer);
+			goto start;
+		}
+	}
+
+	device_links_write_unlock();
+}
+
+/**
+ * device_links_purge - Delete existing links to other devices.
+ * @dev: Target device.
+ */
+static void device_links_purge(struct device *dev)
+{
+	struct device_link *link, *ln;
+
+	/*
+	 * Delete all of the remaining links from this device to any other
+	 * devices (either consumers or suppliers).
+	 */
+	device_links_write_lock();
+
+	list_for_each_entry_safe_reverse(link, ln, &dev->links.suppliers, c_node) {
+		WARN_ON(link->status == DL_STATE_ACTIVE);
+		__device_link_del(link);
+	}
+
+	list_for_each_entry_safe_reverse(link, ln, &dev->links.consumers, s_node) {
+		WARN_ON(link->status != DL_STATE_DORMANT &&
+			link->status != DL_STATE_NONE);
+		__device_link_del(link);
+	}
+
+	device_links_write_unlock();
+}
+
+/* Device links support end. */
+
 int (*platform_notify)(struct device *dev) = NULL;
 int (*platform_notify_remove)(struct device *dev) = NULL;
 static struct kobject *dev_kobj;
@@ -494,8 +1060,14 @@ static int device_add_attrs(struct device *dev)
 			goto err_remove_dev_groups;
 	}
 
+	error = device_create_file(dev, &dev_attr_deferred_probe);
+	if (error)
+		goto err_remove_online;
+
 	return 0;
 
+ err_remove_online:
+	device_remove_file(dev, &dev_attr_online);
  err_remove_dev_groups:
 	device_remove_groups(dev, dev->groups);
  err_remove_type_groups:
@@ -513,6 +1085,7 @@ static void device_remove_attrs(struct device *dev)
 	struct class *class = dev->class;
 	const struct device_type *type = dev->type;
 
+	device_remove_file(dev, &dev_attr_deferred_probe);
 	device_remove_file(dev, &dev_attr_online);
 	device_remove_groups(dev, dev->groups);
 
@@ -711,6 +1284,9 @@ void device_initialize(struct device *dev)
 #ifdef CONFIG_GENERIC_MSI_IRQ
 	INIT_LIST_HEAD(&dev->msi_list);
 #endif
+	INIT_LIST_HEAD(&dev->links.consumers);
+	INIT_LIST_HEAD(&dev->links.suppliers);
+	dev->links.status = DL_DEV_NO_DRIVER;
 }
 EXPORT_SYMBOL_GPL(device_initialize);
 
@@ -1258,6 +1834,8 @@ void device_del(struct device *dev)
 	if (dev->bus)
 		blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 					     BUS_NOTIFY_DEL_DEVICE, dev);
+
+	device_links_purge(dev);
 	dpm_sysfs_remove(dev);
 	if (parent)
 		klist_del(&dev->p->knode_parent);

drivers/base/dd.c

@@ -53,6 +53,19 @@ static LIST_HEAD(deferred_probe_pending_list);
 static LIST_HEAD(deferred_probe_active_list);
 static atomic_t deferred_trigger_count = ATOMIC_INIT(0);
 
+static ssize_t deferred_probe_show(struct device *dev,
+				   struct device_attribute *attr, char *buf)
+{
+	bool value;
+
+	mutex_lock(&deferred_probe_mutex);
+	value = !list_empty(&dev->p->deferred_probe);
+	mutex_unlock(&deferred_probe_mutex);
+
+	return sprintf(buf, "%d\n", value);
+}
+DEVICE_ATTR_RO(deferred_probe);
+
 /*
  * In some cases, like suspend to RAM or hibernation, It might be reasonable
  * to prohibit probing of devices as it could be unsafe.
@@ -244,6 +257,7 @@ static void driver_bound(struct device *dev)
 		 __func__, dev_name(dev));
 
 	klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
+	device_links_driver_bound(dev);
 
 	device_pm_check_callbacks(dev);
 
@@ -337,6 +351,10 @@ static int really_probe(struct device *dev, struct device_driver *drv)
 		return ret;
 	}
 
+	ret = device_links_check_suppliers(dev);
+	if (ret)
+		return ret;
+
 	atomic_inc(&probe_count);
 	pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
 		 drv->bus->name, __func__, drv->name, dev_name(dev));
@@ -415,6 +433,7 @@ probe_failed:
 		blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 					     BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
 pinctrl_bind_failed:
+	device_links_no_driver(dev);
 	devres_release_all(dev);
 	driver_sysfs_remove(dev);
 	dev->driver = NULL;
@@ -507,6 +526,7 @@ int driver_probe_device(struct device_driver *drv, struct device *dev)
 	pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
 		 drv->bus->name, __func__, dev_name(dev), drv->name);
 
+	pm_runtime_get_suppliers(dev);
 	if (dev->parent)
 		pm_runtime_get_sync(dev->parent);
 
@@ -517,6 +537,7 @@ int driver_probe_device(struct device_driver *drv, struct device *dev)
 	if (dev->parent)
 		pm_runtime_put(dev->parent);
 
+	pm_runtime_put_suppliers(dev);
 	return ret;
 }
 
@@ -771,7 +792,7 @@ EXPORT_SYMBOL_GPL(driver_attach);
  * __device_release_driver() must be called with @dev lock held.
  * When called for a USB interface, @dev->parent lock must be held as well.
  */
-static void __device_release_driver(struct device *dev)
+static void __device_release_driver(struct device *dev, struct device *parent)
 {
 	struct device_driver *drv;
 
@@ -780,7 +801,27 @@ static void __device_release_driver(struct device *dev)
 		if (driver_allows_async_probing(drv))
 			async_synchronize_full();
 
+		while (device_links_busy(dev)) {
+			device_unlock(dev);
+			if (parent)
+				device_unlock(parent);
+
+			device_links_unbind_consumers(dev);
+			if (parent)
+				device_lock(parent);
+
+			device_lock(dev);
+			/*
+			 * A concurrent invocation of the same function might
+			 * have released the driver successfully while this one
+			 * was waiting, so check for that.
+			 */
+			if (dev->driver != drv)
+				return;
+		}
+
 		pm_runtime_get_sync(dev);
+		pm_runtime_clean_up_links(dev);
 
 		driver_sysfs_remove(dev);
 
@@ -795,6 +836,8 @@ static void __device_release_driver(struct device *dev)
 			dev->bus->remove(dev);
 		else if (drv->remove)
 			drv->remove(dev);
+
+		device_links_driver_cleanup(dev);
 		devres_release_all(dev);
 		dev->driver = NULL;
 		dev_set_drvdata(dev, NULL);
@@ -811,12 +854,32 @@ static void __device_release_driver(struct device *dev)
 	}
 }
 
+void device_release_driver_internal(struct device *dev,
+				    struct device_driver *drv,
+				    struct device *parent)
+{
+	if (parent)
+		device_lock(parent);
+
+	device_lock(dev);
+	if (!drv || drv == dev->driver)
+		__device_release_driver(dev, parent);
+
+	device_unlock(dev);
+	if (parent)
+		device_unlock(parent);
+}
+
 /**
  * device_release_driver - manually detach device from driver.
  * @dev: device.
  *
  * Manually detach device from driver.
  * When called for a USB interface, @dev->parent lock must be held.
+ *
+ * If this function is to be called with @dev->parent lock held, ensure that
+ * the device's consumers are unbound in advance or that their locks can be
+ * acquired under the @dev->parent lock.
  */
 void device_release_driver(struct device *dev)
 {
@@ -825,9 +888,7 @@ void device_release_driver(struct device *dev)
 	 * within their ->remove callback for the same device, they
 	 * will deadlock right here.
 	 */
-	device_lock(dev);
-	__device_release_driver(dev);
-	device_unlock(dev);
+	device_release_driver_internal(dev, NULL, NULL);
 }
 EXPORT_SYMBOL_GPL(device_release_driver);
 
@@ -852,15 +913,7 @@ void driver_detach(struct device_driver *drv)
 		dev = dev_prv->device;
 		get_device(dev);
 		spin_unlock(&drv->p->klist_devices.k_lock);
-
-		if (dev->parent)	/* Needed for USB */
-			device_lock(dev->parent);
-		device_lock(dev);
-		if (dev->driver == drv)
-			__device_release_driver(dev);
-		device_unlock(dev);
-		if (dev->parent)
-			device_unlock(dev->parent);
+		device_release_driver_internal(dev, drv, dev->parent);
 		put_device(dev);
 	}
 }

drivers/base/power/main.c

@@ -131,6 +131,7 @@ void device_pm_add(struct device *dev)
 		dev_warn(dev, "parent %s should not be sleeping\n",
 			dev_name(dev->parent));
 	list_add_tail(&dev->power.entry, &dpm_list);
+	dev->power.in_dpm_list = true;
 	mutex_unlock(&dpm_list_mtx);
 }
 
@@ -145,6 +146,7 @@ void device_pm_remove(struct device *dev)
 	complete_all(&dev->power.completion);
 	mutex_lock(&dpm_list_mtx);
 	list_del_init(&dev->power.entry);
+	dev->power.in_dpm_list = false;
 	mutex_unlock(&dpm_list_mtx);
 	device_wakeup_disable(dev);
 	pm_runtime_remove(dev);
@@ -244,6 +246,62 @@ static void dpm_wait_for_children(struct device *dev, bool async)
        device_for_each_child(dev, &async, dpm_wait_fn);
 }
 
+static void dpm_wait_for_suppliers(struct device *dev, bool async)
+{
+	struct device_link *link;
+	int idx;
+
+	idx = device_links_read_lock();
+
+	/*
+	 * If the supplier goes away right after we've checked the link to it,
+	 * we'll wait for its completion to change the state, but that's fine,
+	 * because the only things that will block as a result are the SRCU
+	 * callbacks freeing the link objects for the links in the list we're
+	 * walking.
+	 */
+	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node)
+		if (READ_ONCE(link->status) != DL_STATE_DORMANT)
+			dpm_wait(link->supplier, async);
+
+	device_links_read_unlock(idx);
+}
+
+static void dpm_wait_for_superior(struct device *dev, bool async)
+{
+	dpm_wait(dev->parent, async);
+	dpm_wait_for_suppliers(dev, async);
+}
+
+static void dpm_wait_for_consumers(struct device *dev, bool async)
+{
+	struct device_link *link;
+	int idx;
+
+	idx = device_links_read_lock();
+
+	/*
+	 * The status of a device link can only be changed from "dormant" by a
+	 * probe, but that cannot happen during system suspend/resume.  In
+	 * theory it can change to "dormant" at that time, but then it is
+	 * reasonable to wait for the target device anyway (eg. if it goes
+	 * away, it's better to wait for it to go away completely and then
+	 * continue instead of trying to continue in parallel with its
+	 * unregistration).
+	 */
+	list_for_each_entry_rcu(link, &dev->links.consumers, s_node)
+		if (READ_ONCE(link->status) != DL_STATE_DORMANT)
+			dpm_wait(link->consumer, async);
+
+	device_links_read_unlock(idx);
+}
+
+static void dpm_wait_for_subordinate(struct device *dev, bool async)
+{
+	dpm_wait_for_children(dev, async);
+	dpm_wait_for_consumers(dev, async);
+}
+
 /**
  * pm_op - Return the PM operation appropriate for given PM event.
  * @ops: PM operations to choose from.
@@ -488,7 +546,7 @@ static int device_resume_noirq(struct device *dev, pm_message_t state, bool asyn
 	if (!dev->power.is_noirq_suspended)
 		goto Out;
 
-	dpm_wait(dev->parent, async);
+	dpm_wait_for_superior(dev, async);
 
 	if (dev->pm_domain) {
 		info = "noirq power domain ";
@@ -618,7 +676,7 @@ static int device_resume_early(struct device *dev, pm_message_t state, bool asyn
 	if (!dev->power.is_late_suspended)
 		goto Out;
 
-	dpm_wait(dev->parent, async);
+	dpm_wait_for_superior(dev, async);
 
 	if (dev->pm_domain) {
 		info = "early power domain ";
@@ -750,7 +808,7 @@ static int device_resume(struct device *dev, pm_message_t state, bool async)
 		goto Complete;
 	}
 
-	dpm_wait(dev->parent, async);
+	dpm_wait_for_superior(dev, async);
 	dpm_watchdog_set(&wd, dev);
 	device_lock(dev);
 
@@ -1038,7 +1096,7 @@ static int __device_suspend_noirq(struct device *dev, pm_message_t state, bool a
 	if (dev->power.syscore || dev->power.direct_complete)
 		goto Complete;
 
-	dpm_wait_for_children(dev, async);
+	dpm_wait_for_subordinate(dev, async);
 
 	if (dev->pm_domain) {
 		info = "noirq power domain ";
@@ -1185,7 +1243,7 @@ static int __device_suspend_late(struct device *dev, pm_message_t state, bool as
 	if (dev->power.syscore || dev->power.direct_complete)
 		goto Complete;
 
-	dpm_wait_for_children(dev, async);
+	dpm_wait_for_subordinate(dev, async);
 
 	if (dev->pm_domain) {
 		info = "late power domain ";
@@ -1342,6 +1400,22 @@ static int legacy_suspend(struct device *dev, pm_message_t state,
 	return error;
 }
 
+static void dpm_clear_suppliers_direct_complete(struct device *dev)
+{
+	struct device_link *link;
+	int idx;
+
+	idx = device_links_read_lock();
+
+	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node) {
+		spin_lock_irq(&link->supplier->power.lock);
+		link->supplier->power.direct_complete = false;
+		spin_unlock_irq(&link->supplier->power.lock);
+	}
+
+	device_links_read_unlock(idx);
+}
+
 /**
  * device_suspend - Execute "suspend" callbacks for given device.
  * @dev: Device to handle.
@@ -1358,7 +1432,7 @@ static int __device_suspend(struct device *dev, pm_message_t state, bool async)
 	TRACE_DEVICE(dev);
 	TRACE_SUSPEND(0);
 
-	dpm_wait_for_children(dev, async);
+	dpm_wait_for_subordinate(dev, async);
 
 	if (async_error)
 		goto Complete;
@@ -1454,6 +1528,7 @@ static int __device_suspend(struct device *dev, pm_message_t state, bool async)
 
 			spin_unlock_irq(&parent->power.lock);
 		}
+		dpm_clear_suppliers_direct_complete(dev);
 	}
 
 	device_unlock(dev);

drivers/base/power/power.h

@@ -127,6 +127,11 @@ extern void device_pm_move_after(struct device *, struct device *);
 extern void device_pm_move_last(struct device *);
 extern void device_pm_check_callbacks(struct device *dev);
 
+static inline bool device_pm_initialized(struct device *dev)
+{
+	return dev->power.in_dpm_list;
+}
+
 #else /* !CONFIG_PM_SLEEP */
 
 static inline void device_pm_sleep_init(struct device *dev) {}
@@ -146,6 +151,11 @@ static inline void device_pm_move_last(struct device *dev) {}
 
 static inline void device_pm_check_callbacks(struct device *dev) {}
 
+static inline bool device_pm_initialized(struct device *dev)
+{
+	return device_is_registered(dev);
+}
+
 #endif /* !CONFIG_PM_SLEEP */
 
 static inline void device_pm_init(struct device *dev)

drivers/base/power/runtime.c

@@ -12,6 +12,8 @@
 #include <linux/pm_runtime.h>
 #include <linux/pm_wakeirq.h>
 #include <trace/events/rpm.h>
+
+#include "../base.h"
 #include "power.h"
 
 typedef int (*pm_callback_t)(struct device *);
@@ -258,6 +260,42 @@ static int rpm_check_suspend_allowed(struct device *dev)
 	return retval;
 }
 
+static int rpm_get_suppliers(struct device *dev)
+{
+	struct device_link *link;
+
+	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node) {
+		int retval;
+
+		if (!(link->flags & DL_FLAG_PM_RUNTIME))
+			continue;
+
+		if (READ_ONCE(link->status) == DL_STATE_SUPPLIER_UNBIND ||
+		    link->rpm_active)
+			continue;
+
+		retval = pm_runtime_get_sync(link->supplier);
+		if (retval < 0) {
+			pm_runtime_put_noidle(link->supplier);
+			return retval;
+		}
+		link->rpm_active = true;
+	}
+	return 0;
+}
+
+static void rpm_put_suppliers(struct device *dev)
+{
+	struct device_link *link;
+
+	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node)
+		if (link->rpm_active &&
+		    READ_ONCE(link->status) != DL_STATE_SUPPLIER_UNBIND) {
+			pm_runtime_put(link->supplier);
+			link->rpm_active = false;
+		}
+}
+
 /**
  * __rpm_callback - Run a given runtime PM callback for a given device.
  * @cb: Runtime PM callback to run.
@@ -266,19 +304,57 @@ static int rpm_check_suspend_allowed(struct device *dev)
 static int __rpm_callback(int (*cb)(struct device *), struct device *dev)
 	__releases(&dev->power.lock) __acquires(&dev->power.lock)
 {
-	int retval;
+	int retval, idx;
+	bool use_links = dev->power.links_count > 0;
 
-	if (dev->power.irq_safe)
+	if (dev->power.irq_safe) {
 		spin_unlock(&dev->power.lock);
-	else
+	} else {
 		spin_unlock_irq(&dev->power.lock);
 
+		/*
+		 * Resume suppliers if necessary.
+		 *
+		 * The device's runtime PM status cannot change until this
+		 * routine returns, so it is safe to read the status outside of
+		 * the lock.
+		 */
+		if (use_links && dev->power.runtime_status == RPM_RESUMING) {
+			idx = device_links_read_lock();
+
+			retval = rpm_get_suppliers(dev);
+			if (retval)
+				goto fail;
+
+			device_links_read_unlock(idx);
+		}
+	}
+
 	retval = cb(dev);
 
-	if (dev->power.irq_safe)
+	if (dev->power.irq_safe) {
 		spin_lock(&dev->power.lock);
-	else
+	} else {
+		/*
+		 * If the device is suspending and the callback has returned
+		 * success, drop the usage counters of the suppliers that have
+		 * been reference counted on its resume.
+		 *
+		 * Do that if resume fails too.
+		 */
+		if (use_links
+		    && ((dev->power.runtime_status == RPM_SUSPENDING && !retval)
+		    || (dev->power.runtime_status == RPM_RESUMING && retval))) {
+			idx = device_links_read_lock();
+
+ fail:
+			rpm_put_suppliers(dev);
+
+			device_links_read_unlock(idx);
+		}
+
 		spin_lock_irq(&dev->power.lock);
+	}
 
 	return retval;
 }
@@ -1446,6 +1522,94 @@ void pm_runtime_remove(struct device *dev)
 	pm_runtime_reinit(dev);
 }
 
+/**
+ * pm_runtime_clean_up_links - Prepare links to consumers for driver removal.
+ * @dev: Device whose driver is going to be removed.
+ *
+ * Check links from this device to any consumers and if any of them have active
+ * runtime PM references to the device, drop the usage counter of the device
+ * (once per link).
+ *
+ * Links with the DL_FLAG_STATELESS flag set are ignored.
+ *
+ * Since the device is guaranteed to be runtime-active at the point this is
+ * called, nothing else needs to be done here.
+ *
+ * Moreover, this is called after device_links_busy() has returned 'false', so
+ * the status of each link is guaranteed to be DL_STATE_SUPPLIER_UNBIND and
+ * therefore rpm_active can't be manipulated concurrently.
+ */
+void pm_runtime_clean_up_links(struct device *dev)
+{
+	struct device_link *link;
+	int idx;
+
+	idx = device_links_read_lock();
+
+	list_for_each_entry_rcu(link, &dev->links.consumers, s_node) {
+		if (link->flags & DL_FLAG_STATELESS)
+			continue;
+
+		if (link->rpm_active) {
+			pm_runtime_put_noidle(dev);
+			link->rpm_active = false;
+		}
+	}
+
+	device_links_read_unlock(idx);
+}
+
+/**
+ * pm_runtime_get_suppliers - Resume and reference-count supplier devices.
+ * @dev: Consumer device.
+ */
+void pm_runtime_get_suppliers(struct device *dev)
+{
+	struct device_link *link;
+	int idx;
+
+	idx = device_links_read_lock();
+
+	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node)
+		if (link->flags & DL_FLAG_PM_RUNTIME)
+			pm_runtime_get_sync(link->supplier);
+
+	device_links_read_unlock(idx);
+}
+
+/**
+ * pm_runtime_put_suppliers - Drop references to supplier devices.
+ * @dev: Consumer device.
+ */
+void pm_runtime_put_suppliers(struct device *dev)
+{
+	struct device_link *link;
+	int idx;
+
+	idx = device_links_read_lock();
+
+	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node)
+		if (link->flags & DL_FLAG_PM_RUNTIME)
+			pm_runtime_put(link->supplier);
+
+	device_links_read_unlock(idx);
+}
+
+void pm_runtime_new_link(struct device *dev)
+{
+	spin_lock_irq(&dev->power.lock);
+	dev->power.links_count++;
+	spin_unlock_irq(&dev->power.lock);
+}
+
+void pm_runtime_drop_link(struct device *dev)
+{
+	spin_lock_irq(&dev->power.lock);
+	WARN_ON(dev->power.links_count == 0);
+	dev->power.links_count--;
+	spin_unlock_irq(&dev->power.lock);
+}
+
 /**
  * pm_runtime_force_suspend - Force a device into suspend state if needed.
  * @dev: Device to suspend.

drivers/base/test/Kconfig

@@ -0,0 +1,9 @@
+config TEST_ASYNC_DRIVER_PROBE
+	tristate "Build kernel module to test asynchronous driver probing"
+	depends on m
+	help
+	  Enabling this option produces a kernel module that allows
+	  testing asynchronous driver probing by the device core.
+	  The module name will be test_async_driver_probe.ko
+
+	  If unsure say N.

drivers/base/test/Makefile

@@ -0,0 +1 @@
+obj-$(CONFIG_TEST_ASYNC_DRIVER_PROBE)	+= test_async_driver_probe.o

drivers/base/test/test_async_driver_probe.c

@@ -0,0 +1,171 @@
+/*
+ * Copyright (C) 2014 Google, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/hrtimer.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/time.h>
+
+#define TEST_PROBE_DELAY	(5 * 1000)	/* 5 sec */
+#define TEST_PROBE_THRESHOLD	(TEST_PROBE_DELAY / 2)
+
+static int test_probe(struct platform_device *pdev)
+{
+	dev_info(&pdev->dev, "sleeping for %d msecs in probe\n",
+		 TEST_PROBE_DELAY);
+	msleep(TEST_PROBE_DELAY);
+	dev_info(&pdev->dev, "done sleeping\n");
+
+	return 0;
+}
+
+static struct platform_driver async_driver = {
+	.driver = {
+		.name = "test_async_driver",
+		.owner = THIS_MODULE,
+		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
+	},
+	.probe = test_probe,
+};
+
+static struct platform_driver sync_driver = {
+	.driver = {
+		.name = "test_sync_driver",
+		.owner = THIS_MODULE,
+		.probe_type = PROBE_FORCE_SYNCHRONOUS,
+	},
+	.probe = test_probe,
+};
+
+static struct platform_device *async_dev_1, *async_dev_2;
+static struct platform_device *sync_dev_1;
+
+static int __init test_async_probe_init(void)
+{
+	ktime_t calltime, delta;
+	unsigned long long duration;
+	int error;
+
+	pr_info("registering first asynchronous device...\n");
+
+	async_dev_1 = platform_device_register_simple("test_async_driver", 1,
+						      NULL, 0);
+	if (IS_ERR(async_dev_1)) {
+		error = PTR_ERR(async_dev_1);
+		pr_err("failed to create async_dev_1: %d", error);
+		return error;
+	}
+
+	pr_info("registering asynchronous driver...\n");
+	calltime = ktime_get();
+	error = platform_driver_register(&async_driver);
+	if (error) {
+		pr_err("Failed to register async_driver: %d\n", error);
+		goto err_unregister_async_dev_1;
+	}
+
+	delta = ktime_sub(ktime_get(), calltime);
+	duration = (unsigned long long) ktime_to_ms(delta);
+	pr_info("registration took %lld msecs\n", duration);
+	if (duration > TEST_PROBE_THRESHOLD) {
+		pr_err("test failed: probe took too long\n");
+		error = -ETIMEDOUT;
+		goto err_unregister_async_driver;
+	}
+
+	pr_info("registering second asynchronous device...\n");
+	calltime = ktime_get();
+	async_dev_2 = platform_device_register_simple("test_async_driver", 2,
+						      NULL, 0);
+	if (IS_ERR(async_dev_2)) {
+		error = PTR_ERR(async_dev_2);
+		pr_err("failed to create async_dev_2: %d", error);
+		goto err_unregister_async_driver;
+	}
+
+	delta = ktime_sub(ktime_get(), calltime);
+	duration = (unsigned long long) ktime_to_ms(delta);
+	pr_info("registration took %lld msecs\n", duration);
+	if (duration > TEST_PROBE_THRESHOLD) {
+		pr_err("test failed: probe took too long\n");
+		error = -ETIMEDOUT;
+		goto err_unregister_async_dev_2;
+	}
+
+	pr_info("registering synchronous driver...\n");
+
+	error = platform_driver_register(&sync_driver);
+	if (error) {
+		pr_err("Failed to register async_driver: %d\n", error);
+		goto err_unregister_async_dev_2;
+	}
+
+	pr_info("registering synchronous device...\n");
+	calltime = ktime_get();
+	sync_dev_1 = platform_device_register_simple("test_sync_driver", 1,
+						     NULL, 0);
+	if (IS_ERR(async_dev_1)) {
+		error = PTR_ERR(sync_dev_1);
+		pr_err("failed to create sync_dev_1: %d", error);
+		goto err_unregister_sync_driver;
+	}
+
+	delta = ktime_sub(ktime_get(), calltime);
+	duration = (unsigned long long) ktime_to_ms(delta);
+	pr_info("registration took %lld msecs\n", duration);
+	if (duration < TEST_PROBE_THRESHOLD) {
+		pr_err("test failed: probe was too quick\n");
+		error = -ETIMEDOUT;
+		goto err_unregister_sync_dev_1;
+	}
+
+	pr_info("completed successfully");
+
+	return 0;
+
+err_unregister_sync_dev_1:
+	platform_device_unregister(sync_dev_1);
+
+err_unregister_sync_driver:
+	platform_driver_unregister(&sync_driver);
+
+err_unregister_async_dev_2:
+	platform_device_unregister(async_dev_2);
+
+err_unregister_async_driver:
+	platform_driver_unregister(&async_driver);
+
+err_unregister_async_dev_1:
+	platform_device_unregister(async_dev_1);
+
+	return error;
+}
+module_init(test_async_probe_init);
+
+static void __exit test_async_probe_exit(void)
+{
+	platform_driver_unregister(&async_driver);
+	platform_driver_unregister(&sync_driver);
+	platform_device_unregister(async_dev_1);
+	platform_device_unregister(async_dev_2);
+	platform_device_unregister(sync_dev_1);
+}
+module_exit(test_async_probe_exit);
+
+MODULE_DESCRIPTION("Test module for asynchronous driver probing");
+MODULE_AUTHOR("Dmitry Torokhov <dtor@chromium.org>");
+MODULE_LICENSE("GPL");

include/linux/cacheinfo.h

@@ -71,6 +71,7 @@ struct cpu_cacheinfo {
 	struct cacheinfo *info_list;
 	unsigned int num_levels;
 	unsigned int num_leaves;
+	bool cpu_map_populated;
 };
 
 /*

include/linux/debugfs.h

@@ -62,6 +62,21 @@ static inline const struct file_operations *debugfs_real_fops(struct file *filp)
 	return filp->f_path.dentry->d_fsdata;
 }
 
+#define DEFINE_DEBUGFS_ATTRIBUTE(__fops, __get, __set, __fmt)		\
+static int __fops ## _open(struct inode *inode, struct file *file)	\
+{									\
+	__simple_attr_check_format(__fmt, 0ull);			\
+	return simple_attr_open(inode, file, __get, __set, __fmt);	\
+}									\
+static const struct file_operations __fops = {				\
+	.owner	 = THIS_MODULE,						\
+	.open	 = __fops ## _open,					\
+	.release = simple_attr_release,					\
+	.read	 = debugfs_attr_read,					\
+	.write	 = debugfs_attr_write,					\
+	.llseek  = generic_file_llseek,					\
+}
+
 #if defined(CONFIG_DEBUG_FS)
 
 struct dentry *debugfs_create_file(const char *name, umode_t mode,
@@ -99,21 +114,6 @@ ssize_t debugfs_attr_read(struct file *file, char __user *buf,
 ssize_t debugfs_attr_write(struct file *file, const char __user *buf,
 			size_t len, loff_t *ppos);
 
-#define DEFINE_DEBUGFS_ATTRIBUTE(__fops, __get, __set, __fmt)		\
-static int __fops ## _open(struct inode *inode, struct file *file)	\
-{									\
-	__simple_attr_check_format(__fmt, 0ull);			\
-	return simple_attr_open(inode, file, __get, __set, __fmt);	\
-}									\
-static const struct file_operations __fops = {				\
-	.owner	 = THIS_MODULE,					\
-	.open	 = __fops ## _open,					\
-	.release = simple_attr_release,				\
-	.read	 = debugfs_attr_read,					\
-	.write	 = debugfs_attr_write,					\
-	.llseek  = generic_file_llseek,				\
-}
-
 struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
                 struct dentry *new_dir, const char *new_name);
 
@@ -233,8 +233,18 @@ static inline void debugfs_use_file_finish(int srcu_idx)
 	__releases(&debugfs_srcu)
 { }
 
-#define DEFINE_DEBUGFS_ATTRIBUTE(__fops, __get, __set, __fmt)	\
-	static const struct file_operations __fops = { 0 }
+static inline ssize_t debugfs_attr_read(struct file *file, char __user *buf,
+					size_t len, loff_t *ppos)
+{
+	return -ENODEV;
+}
+
+static inline ssize_t debugfs_attr_write(struct file *file,
+					const char __user *buf,
+					size_t len, loff_t *ppos)
+{
+	return -ENODEV;
+}
 
 static inline struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
                 struct dentry *new_dir, char *new_name)

include/linux/device.h

@@ -707,6 +707,87 @@ struct device_dma_parameters {
 	unsigned long segment_boundary_mask;
 };
 
+/**
+ * enum device_link_state - Device link states.
+ * @DL_STATE_NONE: The presence of the drivers is not being tracked.
+ * @DL_STATE_DORMANT: None of the supplier/consumer drivers is present.
+ * @DL_STATE_AVAILABLE: The supplier driver is present, but the consumer is not.
+ * @DL_STATE_CONSUMER_PROBE: The consumer is probing (supplier driver present).
+ * @DL_STATE_ACTIVE: Both the supplier and consumer drivers are present.
+ * @DL_STATE_SUPPLIER_UNBIND: The supplier driver is unbinding.
+ */
+enum device_link_state {
+	DL_STATE_NONE = -1,
+	DL_STATE_DORMANT = 0,
+	DL_STATE_AVAILABLE,
+	DL_STATE_CONSUMER_PROBE,
+	DL_STATE_ACTIVE,
+	DL_STATE_SUPPLIER_UNBIND,
+};
+
+/*
+ * Device link flags.
+ *
+ * STATELESS: The core won't track the presence of supplier/consumer drivers.
+ * AUTOREMOVE: Remove this link automatically on consumer driver unbind.
+ * PM_RUNTIME: If set, the runtime PM framework will use this link.
+ * RPM_ACTIVE: Run pm_runtime_get_sync() on the supplier during link creation.
+ */
+#define DL_FLAG_STATELESS	BIT(0)
+#define DL_FLAG_AUTOREMOVE	BIT(1)
+#define DL_FLAG_PM_RUNTIME	BIT(2)
+#define DL_FLAG_RPM_ACTIVE	BIT(3)
+
+/**
+ * struct device_link - Device link representation.
+ * @supplier: The device on the supplier end of the link.
+ * @s_node: Hook to the supplier device's list of links to consumers.
+ * @consumer: The device on the consumer end of the link.
+ * @c_node: Hook to the consumer device's list of links to suppliers.
+ * @status: The state of the link (with respect to the presence of drivers).
+ * @flags: Link flags.
+ * @rpm_active: Whether or not the consumer device is runtime-PM-active.
+ * @rcu_head: An RCU head to use for deferred execution of SRCU callbacks.
+ */
+struct device_link {
+	struct device *supplier;
+	struct list_head s_node;
+	struct device *consumer;
+	struct list_head c_node;
+	enum device_link_state status;
+	u32 flags;
+	bool rpm_active;
+#ifdef CONFIG_SRCU
+	struct rcu_head rcu_head;
+#endif
+};
+
+/**
+ * enum dl_dev_state - Device driver presence tracking information.
+ * @DL_DEV_NO_DRIVER: There is no driver attached to the device.
+ * @DL_DEV_PROBING: A driver is probing.
+ * @DL_DEV_DRIVER_BOUND: The driver has been bound to the device.
+ * @DL_DEV_UNBINDING: The driver is unbinding from the device.
+ */
+enum dl_dev_state {
+	DL_DEV_NO_DRIVER = 0,
+	DL_DEV_PROBING,
+	DL_DEV_DRIVER_BOUND,
+	DL_DEV_UNBINDING,
+};
+
+/**
+ * struct dev_links_info - Device data related to device links.
+ * @suppliers: List of links to supplier devices.
+ * @consumers: List of links to consumer devices.
+ * @status: Driver status information.
+ */
+struct dev_links_info {
+	struct list_head suppliers;
+	struct list_head consumers;
+	enum dl_dev_state status;
+};
+
 /**
  * struct device - The basic device structure
  * @parent:	The device's "parent" device, the device to which it is attached.
@@ -799,6 +880,7 @@ struct device {
 					   core doesn't touch it */
 	void		*driver_data;	/* Driver data, set and get with
 					   dev_set/get_drvdata */
+	struct dev_links_info	links;
 	struct dev_pm_info	power;
 	struct dev_pm_domain	*pm_domain;
 
@@ -1116,6 +1198,10 @@ extern void device_shutdown(void);
 /* debugging and troubleshooting/diagnostic helpers. */
 extern const char *dev_driver_string(const struct device *dev);
 
+/* Device links interface. */
+struct device_link *device_link_add(struct device *consumer,
+				    struct device *supplier, u32 flags);
+void device_link_del(struct device_link *link);
 
 #ifdef CONFIG_PRINTK
 

include/linux/pm.h

@@ -559,6 +559,7 @@ struct dev_pm_info {
 	pm_message_t		power_state;
 	unsigned int		can_wakeup:1;
 	unsigned int		async_suspend:1;
+	bool			in_dpm_list:1;	/* Owned by the PM core */
 	bool			is_prepared:1;	/* Owned by the PM core */
 	bool			is_suspended:1;	/* Ditto */
 	bool			is_noirq_suspended:1;
@@ -596,6 +597,7 @@ struct dev_pm_info {
 	unsigned int		use_autosuspend:1;
 	unsigned int		timer_autosuspends:1;
 	unsigned int		memalloc_noio:1;
+	unsigned int		links_count;
 	enum rpm_request	request;
 	enum rpm_status		runtime_status;
 	int			runtime_error;

include/linux/pm_runtime.h

@@ -55,6 +55,11 @@ extern unsigned long pm_runtime_autosuspend_expiration(struct device *dev);
 extern void pm_runtime_update_max_time_suspended(struct device *dev,
 						 s64 delta_ns);
 extern void pm_runtime_set_memalloc_noio(struct device *dev, bool enable);
+extern void pm_runtime_clean_up_links(struct device *dev);
+extern void pm_runtime_get_suppliers(struct device *dev);
+extern void pm_runtime_put_suppliers(struct device *dev);
+extern void pm_runtime_new_link(struct device *dev);
+extern void pm_runtime_drop_link(struct device *dev);
 
 static inline void pm_suspend_ignore_children(struct device *dev, bool enable)
 {
@@ -186,6 +191,11 @@ static inline unsigned long pm_runtime_autosuspend_expiration(
 				struct device *dev) { return 0; }
 static inline void pm_runtime_set_memalloc_noio(struct device *dev,
 						bool enable){}
+static inline void pm_runtime_clean_up_links(struct device *dev) {}
+static inline void pm_runtime_get_suppliers(struct device *dev) {}
+static inline void pm_runtime_put_suppliers(struct device *dev) {}
+static inline void pm_runtime_new_link(struct device *dev) {}
+static inline void pm_runtime_drop_link(struct device *dev) {}
 
 #endif /* !CONFIG_PM */
 

lib/kobject_uevent.c

@@ -56,7 +56,7 @@ static const char *kobject_actions[] = {
  * kobject_action_type - translate action string to numeric type
  *
  * @buf: buffer containing the action string, newline is ignored
- * @len: length of buffer
+ * @count: length of buffer
  * @type: pointer to the location to store the action type
  *
  * Returns 0 if the action string was recognized.
@@ -154,8 +154,8 @@ static void cleanup_uevent_env(struct subprocess_info *info)
 /**
  * kobject_uevent_env - send an uevent with environmental data
  *
- * @action: action that is happening
  * @kobj: struct kobject that the action is happening to
+ * @action: action that is happening
  * @envp_ext: pointer to environmental data
  *
  * Returns 0 if kobject_uevent_env() is completed with success or the
@@ -363,8 +363,8 @@ EXPORT_SYMBOL_GPL(kobject_uevent_env);
 /**
  * kobject_uevent - notify userspace by sending an uevent
  *
- * @action: action that is happening
  * @kobj: struct kobject that the action is happening to
+ * @action: action that is happening
  *
  * Returns 0 if kobject_uevent() is completed with success or the
  * corresponding error when it fails.