workqueue.h 21 KB

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  1. /*
  2. * workqueue.h --- work queue handling for Linux.
  3. */
  4. #ifndef _LINUX_WORKQUEUE_H
  5. #define _LINUX_WORKQUEUE_H
  6. #include <linux/timer.h>
  7. #include <linux/linkage.h>
  8. #include <linux/bitops.h>
  9. #include <linux/lockdep.h>
  10. #include <linux/threads.h>
  11. #include <linux/atomic.h>
  12. #include <linux/cpumask.h>
  13. struct workqueue_struct;
  14. struct work_struct;
  15. typedef void (*work_func_t)(struct work_struct *work);
  16. void delayed_work_timer_fn(unsigned long __data);
  17. /*
  18. * The first word is the work queue pointer and the flags rolled into
  19. * one
  20. */
  21. #define work_data_bits(work) ((unsigned long *)(&(work)->data))
  22. enum {
  23. WORK_STRUCT_PENDING_BIT = 0, /* work item is pending execution */
  24. WORK_STRUCT_DELAYED_BIT = 1, /* work item is delayed */
  25. WORK_STRUCT_PWQ_BIT = 2, /* data points to pwq */
  26. WORK_STRUCT_LINKED_BIT = 3, /* next work is linked to this one */
  27. #ifdef CONFIG_DEBUG_OBJECTS_WORK
  28. WORK_STRUCT_STATIC_BIT = 4, /* static initializer (debugobjects) */
  29. WORK_STRUCT_COLOR_SHIFT = 5, /* color for workqueue flushing */
  30. #else
  31. WORK_STRUCT_COLOR_SHIFT = 4, /* color for workqueue flushing */
  32. #endif
  33. WORK_STRUCT_COLOR_BITS = 4,
  34. WORK_STRUCT_PENDING = 1 << WORK_STRUCT_PENDING_BIT,
  35. WORK_STRUCT_DELAYED = 1 << WORK_STRUCT_DELAYED_BIT,
  36. WORK_STRUCT_PWQ = 1 << WORK_STRUCT_PWQ_BIT,
  37. WORK_STRUCT_LINKED = 1 << WORK_STRUCT_LINKED_BIT,
  38. #ifdef CONFIG_DEBUG_OBJECTS_WORK
  39. WORK_STRUCT_STATIC = 1 << WORK_STRUCT_STATIC_BIT,
  40. #else
  41. WORK_STRUCT_STATIC = 0,
  42. #endif
  43. /*
  44. * The last color is no color used for works which don't
  45. * participate in workqueue flushing.
  46. */
  47. WORK_NR_COLORS = (1 << WORK_STRUCT_COLOR_BITS) - 1,
  48. WORK_NO_COLOR = WORK_NR_COLORS,
  49. /* not bound to any CPU, prefer the local CPU */
  50. WORK_CPU_UNBOUND = NR_CPUS,
  51. /*
  52. * Reserve 7 bits off of pwq pointer w/ debugobjects turned off.
  53. * This makes pwqs aligned to 256 bytes and allows 15 workqueue
  54. * flush colors.
  55. */
  56. WORK_STRUCT_FLAG_BITS = WORK_STRUCT_COLOR_SHIFT +
  57. WORK_STRUCT_COLOR_BITS,
  58. /* data contains off-queue information when !WORK_STRUCT_PWQ */
  59. WORK_OFFQ_FLAG_BASE = WORK_STRUCT_COLOR_SHIFT,
  60. __WORK_OFFQ_CANCELING = WORK_OFFQ_FLAG_BASE,
  61. WORK_OFFQ_CANCELING = (1 << __WORK_OFFQ_CANCELING),
  62. /*
  63. * When a work item is off queue, its high bits point to the last
  64. * pool it was on. Cap at 31 bits and use the highest number to
  65. * indicate that no pool is associated.
  66. */
  67. WORK_OFFQ_FLAG_BITS = 1,
  68. WORK_OFFQ_POOL_SHIFT = WORK_OFFQ_FLAG_BASE + WORK_OFFQ_FLAG_BITS,
  69. WORK_OFFQ_LEFT = BITS_PER_LONG - WORK_OFFQ_POOL_SHIFT,
  70. WORK_OFFQ_POOL_BITS = WORK_OFFQ_LEFT <= 31 ? WORK_OFFQ_LEFT : 31,
  71. WORK_OFFQ_POOL_NONE = (1LU << WORK_OFFQ_POOL_BITS) - 1,
  72. /* convenience constants */
  73. WORK_STRUCT_FLAG_MASK = (1UL << WORK_STRUCT_FLAG_BITS) - 1,
  74. WORK_STRUCT_WQ_DATA_MASK = ~WORK_STRUCT_FLAG_MASK,
  75. WORK_STRUCT_NO_POOL = (unsigned long)WORK_OFFQ_POOL_NONE << WORK_OFFQ_POOL_SHIFT,
  76. /* bit mask for work_busy() return values */
  77. WORK_BUSY_PENDING = 1 << 0,
  78. WORK_BUSY_RUNNING = 1 << 1,
  79. /* maximum string length for set_worker_desc() */
  80. WORKER_DESC_LEN = 24,
  81. };
  82. struct work_struct {
  83. atomic_long_t data;
  84. struct list_head entry;
  85. work_func_t func;
  86. #ifdef CONFIG_LOCKDEP
  87. struct lockdep_map lockdep_map;
  88. #endif
  89. };
  90. #define WORK_DATA_INIT() ATOMIC_LONG_INIT((unsigned long)WORK_STRUCT_NO_POOL)
  91. #define WORK_DATA_STATIC_INIT() \
  92. ATOMIC_LONG_INIT((unsigned long)(WORK_STRUCT_NO_POOL | WORK_STRUCT_STATIC))
  93. struct delayed_work {
  94. struct work_struct work;
  95. struct timer_list timer;
  96. /* target workqueue and CPU ->timer uses to queue ->work */
  97. struct workqueue_struct *wq;
  98. int cpu;
  99. };
  100. /**
  101. * struct workqueue_attrs - A struct for workqueue attributes.
  102. *
  103. * This can be used to change attributes of an unbound workqueue.
  104. */
  105. struct workqueue_attrs {
  106. /**
  107. * @nice: nice level
  108. */
  109. int nice;
  110. /**
  111. * @cpumask: allowed CPUs
  112. */
  113. cpumask_var_t cpumask;
  114. /**
  115. * @no_numa: disable NUMA affinity
  116. *
  117. * Unlike other fields, ``no_numa`` isn't a property of a worker_pool. It
  118. * only modifies how :c:func:`apply_workqueue_attrs` select pools and thus
  119. * doesn't participate in pool hash calculations or equality comparisons.
  120. */
  121. bool no_numa;
  122. };
  123. static inline struct delayed_work *to_delayed_work(struct work_struct *work)
  124. {
  125. return container_of(work, struct delayed_work, work);
  126. }
  127. struct execute_work {
  128. struct work_struct work;
  129. };
  130. #ifdef CONFIG_LOCKDEP
  131. /*
  132. * NB: because we have to copy the lockdep_map, setting _key
  133. * here is required, otherwise it could get initialised to the
  134. * copy of the lockdep_map!
  135. */
  136. #define __WORK_INIT_LOCKDEP_MAP(n, k) \
  137. .lockdep_map = STATIC_LOCKDEP_MAP_INIT(n, k),
  138. #else
  139. #define __WORK_INIT_LOCKDEP_MAP(n, k)
  140. #endif
  141. #define __WORK_INITIALIZER(n, f) { \
  142. .data = WORK_DATA_STATIC_INIT(), \
  143. .entry = { &(n).entry, &(n).entry }, \
  144. .func = (f), \
  145. __WORK_INIT_LOCKDEP_MAP(#n, &(n)) \
  146. }
  147. #define __DELAYED_WORK_INITIALIZER(n, f, tflags) { \
  148. .work = __WORK_INITIALIZER((n).work, (f)), \
  149. .timer = __TIMER_INITIALIZER(delayed_work_timer_fn, \
  150. 0, (unsigned long)&(n), \
  151. (tflags) | TIMER_IRQSAFE), \
  152. }
  153. #define DECLARE_WORK(n, f) \
  154. struct work_struct n = __WORK_INITIALIZER(n, f)
  155. #define DECLARE_DELAYED_WORK(n, f) \
  156. struct delayed_work n = __DELAYED_WORK_INITIALIZER(n, f, 0)
  157. #define DECLARE_DEFERRABLE_WORK(n, f) \
  158. struct delayed_work n = __DELAYED_WORK_INITIALIZER(n, f, TIMER_DEFERRABLE)
  159. #ifdef CONFIG_DEBUG_OBJECTS_WORK
  160. extern void __init_work(struct work_struct *work, int onstack);
  161. extern void destroy_work_on_stack(struct work_struct *work);
  162. extern void destroy_delayed_work_on_stack(struct delayed_work *work);
  163. static inline unsigned int work_static(struct work_struct *work)
  164. {
  165. return *work_data_bits(work) & WORK_STRUCT_STATIC;
  166. }
  167. #else
  168. static inline void __init_work(struct work_struct *work, int onstack) { }
  169. static inline void destroy_work_on_stack(struct work_struct *work) { }
  170. static inline void destroy_delayed_work_on_stack(struct delayed_work *work) { }
  171. static inline unsigned int work_static(struct work_struct *work) { return 0; }
  172. #endif
  173. /*
  174. * initialize all of a work item in one go
  175. *
  176. * NOTE! No point in using "atomic_long_set()": using a direct
  177. * assignment of the work data initializer allows the compiler
  178. * to generate better code.
  179. */
  180. #ifdef CONFIG_LOCKDEP
  181. #define __INIT_WORK(_work, _func, _onstack) \
  182. do { \
  183. static struct lock_class_key __key; \
  184. \
  185. __init_work((_work), _onstack); \
  186. (_work)->data = (atomic_long_t) WORK_DATA_INIT(); \
  187. lockdep_init_map(&(_work)->lockdep_map, #_work, &__key, 0); \
  188. INIT_LIST_HEAD(&(_work)->entry); \
  189. (_work)->func = (_func); \
  190. } while (0)
  191. #else
  192. #define __INIT_WORK(_work, _func, _onstack) \
  193. do { \
  194. __init_work((_work), _onstack); \
  195. (_work)->data = (atomic_long_t) WORK_DATA_INIT(); \
  196. INIT_LIST_HEAD(&(_work)->entry); \
  197. (_work)->func = (_func); \
  198. } while (0)
  199. #endif
  200. #define INIT_WORK(_work, _func) \
  201. __INIT_WORK((_work), (_func), 0)
  202. #define INIT_WORK_ONSTACK(_work, _func) \
  203. __INIT_WORK((_work), (_func), 1)
  204. #define __INIT_DELAYED_WORK(_work, _func, _tflags) \
  205. do { \
  206. INIT_WORK(&(_work)->work, (_func)); \
  207. __setup_timer(&(_work)->timer, delayed_work_timer_fn, \
  208. (unsigned long)(_work), \
  209. (_tflags) | TIMER_IRQSAFE); \
  210. } while (0)
  211. #define __INIT_DELAYED_WORK_ONSTACK(_work, _func, _tflags) \
  212. do { \
  213. INIT_WORK_ONSTACK(&(_work)->work, (_func)); \
  214. __setup_timer_on_stack(&(_work)->timer, \
  215. delayed_work_timer_fn, \
  216. (unsigned long)(_work), \
  217. (_tflags) | TIMER_IRQSAFE); \
  218. } while (0)
  219. #define INIT_DELAYED_WORK(_work, _func) \
  220. __INIT_DELAYED_WORK(_work, _func, 0)
  221. #define INIT_DELAYED_WORK_ONSTACK(_work, _func) \
  222. __INIT_DELAYED_WORK_ONSTACK(_work, _func, 0)
  223. #define INIT_DEFERRABLE_WORK(_work, _func) \
  224. __INIT_DELAYED_WORK(_work, _func, TIMER_DEFERRABLE)
  225. #define INIT_DEFERRABLE_WORK_ONSTACK(_work, _func) \
  226. __INIT_DELAYED_WORK_ONSTACK(_work, _func, TIMER_DEFERRABLE)
  227. /**
  228. * work_pending - Find out whether a work item is currently pending
  229. * @work: The work item in question
  230. */
  231. #define work_pending(work) \
  232. test_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))
  233. /**
  234. * delayed_work_pending - Find out whether a delayable work item is currently
  235. * pending
  236. * @w: The work item in question
  237. */
  238. #define delayed_work_pending(w) \
  239. work_pending(&(w)->work)
  240. /*
  241. * Workqueue flags and constants. For details, please refer to
  242. * Documentation/core-api/workqueue.rst.
  243. */
  244. enum {
  245. WQ_UNBOUND = 1 << 1, /* not bound to any cpu */
  246. WQ_FREEZABLE = 1 << 2, /* freeze during suspend */
  247. WQ_MEM_RECLAIM = 1 << 3, /* may be used for memory reclaim */
  248. WQ_HIGHPRI = 1 << 4, /* high priority */
  249. WQ_CPU_INTENSIVE = 1 << 5, /* cpu intensive workqueue */
  250. WQ_SYSFS = 1 << 6, /* visible in sysfs, see wq_sysfs_register() */
  251. /*
  252. * Per-cpu workqueues are generally preferred because they tend to
  253. * show better performance thanks to cache locality. Per-cpu
  254. * workqueues exclude the scheduler from choosing the CPU to
  255. * execute the worker threads, which has an unfortunate side effect
  256. * of increasing power consumption.
  257. *
  258. * The scheduler considers a CPU idle if it doesn't have any task
  259. * to execute and tries to keep idle cores idle to conserve power;
  260. * however, for example, a per-cpu work item scheduled from an
  261. * interrupt handler on an idle CPU will force the scheduler to
  262. * excute the work item on that CPU breaking the idleness, which in
  263. * turn may lead to more scheduling choices which are sub-optimal
  264. * in terms of power consumption.
  265. *
  266. * Workqueues marked with WQ_POWER_EFFICIENT are per-cpu by default
  267. * but become unbound if workqueue.power_efficient kernel param is
  268. * specified. Per-cpu workqueues which are identified to
  269. * contribute significantly to power-consumption are identified and
  270. * marked with this flag and enabling the power_efficient mode
  271. * leads to noticeable power saving at the cost of small
  272. * performance disadvantage.
  273. *
  274. * http://thread.gmane.org/gmane.linux.kernel/1480396
  275. */
  276. WQ_POWER_EFFICIENT = 1 << 7,
  277. __WQ_DRAINING = 1 << 16, /* internal: workqueue is draining */
  278. __WQ_ORDERED = 1 << 17, /* internal: workqueue is ordered */
  279. __WQ_ORDERED_EXPLICIT = 1 << 18, /* internal: alloc_ordered_workqueue() */
  280. __WQ_LEGACY = 1 << 18, /* internal: create*_workqueue() */
  281. WQ_MAX_ACTIVE = 512, /* I like 512, better ideas? */
  282. WQ_MAX_UNBOUND_PER_CPU = 4, /* 4 * #cpus for unbound wq */
  283. WQ_DFL_ACTIVE = WQ_MAX_ACTIVE / 2,
  284. };
  285. /* unbound wq's aren't per-cpu, scale max_active according to #cpus */
  286. #define WQ_UNBOUND_MAX_ACTIVE \
  287. max_t(int, WQ_MAX_ACTIVE, num_possible_cpus() * WQ_MAX_UNBOUND_PER_CPU)
  288. /*
  289. * System-wide workqueues which are always present.
  290. *
  291. * system_wq is the one used by schedule[_delayed]_work[_on]().
  292. * Multi-CPU multi-threaded. There are users which expect relatively
  293. * short queue flush time. Don't queue works which can run for too
  294. * long.
  295. *
  296. * system_highpri_wq is similar to system_wq but for work items which
  297. * require WQ_HIGHPRI.
  298. *
  299. * system_long_wq is similar to system_wq but may host long running
  300. * works. Queue flushing might take relatively long.
  301. *
  302. * system_unbound_wq is unbound workqueue. Workers are not bound to
  303. * any specific CPU, not concurrency managed, and all queued works are
  304. * executed immediately as long as max_active limit is not reached and
  305. * resources are available.
  306. *
  307. * system_freezable_wq is equivalent to system_wq except that it's
  308. * freezable.
  309. *
  310. * *_power_efficient_wq are inclined towards saving power and converted
  311. * into WQ_UNBOUND variants if 'wq_power_efficient' is enabled; otherwise,
  312. * they are same as their non-power-efficient counterparts - e.g.
  313. * system_power_efficient_wq is identical to system_wq if
  314. * 'wq_power_efficient' is disabled. See WQ_POWER_EFFICIENT for more info.
  315. */
  316. extern struct workqueue_struct *system_wq;
  317. extern struct workqueue_struct *system_highpri_wq;
  318. extern struct workqueue_struct *system_long_wq;
  319. extern struct workqueue_struct *system_unbound_wq;
  320. extern struct workqueue_struct *system_freezable_wq;
  321. extern struct workqueue_struct *system_power_efficient_wq;
  322. extern struct workqueue_struct *system_freezable_power_efficient_wq;
  323. extern struct workqueue_struct *
  324. __alloc_workqueue_key(const char *fmt, unsigned int flags, int max_active,
  325. struct lock_class_key *key, const char *lock_name, ...) __printf(1, 6);
  326. /**
  327. * alloc_workqueue - allocate a workqueue
  328. * @fmt: printf format for the name of the workqueue
  329. * @flags: WQ_* flags
  330. * @max_active: max in-flight work items, 0 for default
  331. * @args...: args for @fmt
  332. *
  333. * Allocate a workqueue with the specified parameters. For detailed
  334. * information on WQ_* flags, please refer to
  335. * Documentation/core-api/workqueue.rst.
  336. *
  337. * The __lock_name macro dance is to guarantee that single lock_class_key
  338. * doesn't end up with different namesm, which isn't allowed by lockdep.
  339. *
  340. * RETURNS:
  341. * Pointer to the allocated workqueue on success, %NULL on failure.
  342. */
  343. #ifdef CONFIG_LOCKDEP
  344. #define alloc_workqueue(fmt, flags, max_active, args...) \
  345. ({ \
  346. static struct lock_class_key __key; \
  347. const char *__lock_name; \
  348. \
  349. __lock_name = #fmt#args; \
  350. \
  351. __alloc_workqueue_key((fmt), (flags), (max_active), \
  352. &__key, __lock_name, ##args); \
  353. })
  354. #else
  355. #define alloc_workqueue(fmt, flags, max_active, args...) \
  356. __alloc_workqueue_key((fmt), (flags), (max_active), \
  357. NULL, NULL, ##args)
  358. #endif
  359. /**
  360. * alloc_ordered_workqueue - allocate an ordered workqueue
  361. * @fmt: printf format for the name of the workqueue
  362. * @flags: WQ_* flags (only WQ_FREEZABLE and WQ_MEM_RECLAIM are meaningful)
  363. * @args...: args for @fmt
  364. *
  365. * Allocate an ordered workqueue. An ordered workqueue executes at
  366. * most one work item at any given time in the queued order. They are
  367. * implemented as unbound workqueues with @max_active of one.
  368. *
  369. * RETURNS:
  370. * Pointer to the allocated workqueue on success, %NULL on failure.
  371. */
  372. #define alloc_ordered_workqueue(fmt, flags, args...) \
  373. alloc_workqueue(fmt, WQ_UNBOUND | __WQ_ORDERED | \
  374. __WQ_ORDERED_EXPLICIT | (flags), 1, ##args)
  375. #define create_workqueue(name) \
  376. alloc_workqueue("%s", __WQ_LEGACY | WQ_MEM_RECLAIM, 1, (name))
  377. #define create_freezable_workqueue(name) \
  378. alloc_workqueue("%s", __WQ_LEGACY | WQ_FREEZABLE | WQ_UNBOUND | \
  379. WQ_MEM_RECLAIM, 1, (name))
  380. #define create_singlethread_workqueue(name) \
  381. alloc_ordered_workqueue("%s", __WQ_LEGACY | WQ_MEM_RECLAIM, name)
  382. extern void destroy_workqueue(struct workqueue_struct *wq);
  383. struct workqueue_attrs *alloc_workqueue_attrs(gfp_t gfp_mask);
  384. void free_workqueue_attrs(struct workqueue_attrs *attrs);
  385. int apply_workqueue_attrs(struct workqueue_struct *wq,
  386. const struct workqueue_attrs *attrs);
  387. int workqueue_set_unbound_cpumask(cpumask_var_t cpumask);
  388. extern bool queue_work_on(int cpu, struct workqueue_struct *wq,
  389. struct work_struct *work);
  390. extern bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
  391. struct delayed_work *work, unsigned long delay);
  392. extern bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq,
  393. struct delayed_work *dwork, unsigned long delay);
  394. extern void flush_workqueue(struct workqueue_struct *wq);
  395. extern void drain_workqueue(struct workqueue_struct *wq);
  396. extern int schedule_on_each_cpu(work_func_t func);
  397. int execute_in_process_context(work_func_t fn, struct execute_work *);
  398. extern bool flush_work(struct work_struct *work);
  399. extern bool cancel_work(struct work_struct *work);
  400. extern bool cancel_work_sync(struct work_struct *work);
  401. extern bool flush_delayed_work(struct delayed_work *dwork);
  402. extern bool cancel_delayed_work(struct delayed_work *dwork);
  403. extern bool cancel_delayed_work_sync(struct delayed_work *dwork);
  404. extern void workqueue_set_max_active(struct workqueue_struct *wq,
  405. int max_active);
  406. extern bool current_is_workqueue_rescuer(void);
  407. extern bool workqueue_congested(int cpu, struct workqueue_struct *wq);
  408. extern unsigned int work_busy(struct work_struct *work);
  409. extern __printf(1, 2) void set_worker_desc(const char *fmt, ...);
  410. extern void print_worker_info(const char *log_lvl, struct task_struct *task);
  411. extern void show_workqueue_state(void);
  412. /**
  413. * queue_work - queue work on a workqueue
  414. * @wq: workqueue to use
  415. * @work: work to queue
  416. *
  417. * Returns %false if @work was already on a queue, %true otherwise.
  418. *
  419. * We queue the work to the CPU on which it was submitted, but if the CPU dies
  420. * it can be processed by another CPU.
  421. */
  422. static inline bool queue_work(struct workqueue_struct *wq,
  423. struct work_struct *work)
  424. {
  425. return queue_work_on(WORK_CPU_UNBOUND, wq, work);
  426. }
  427. /**
  428. * queue_delayed_work - queue work on a workqueue after delay
  429. * @wq: workqueue to use
  430. * @dwork: delayable work to queue
  431. * @delay: number of jiffies to wait before queueing
  432. *
  433. * Equivalent to queue_delayed_work_on() but tries to use the local CPU.
  434. */
  435. static inline bool queue_delayed_work(struct workqueue_struct *wq,
  436. struct delayed_work *dwork,
  437. unsigned long delay)
  438. {
  439. return queue_delayed_work_on(WORK_CPU_UNBOUND, wq, dwork, delay);
  440. }
  441. /**
  442. * mod_delayed_work - modify delay of or queue a delayed work
  443. * @wq: workqueue to use
  444. * @dwork: work to queue
  445. * @delay: number of jiffies to wait before queueing
  446. *
  447. * mod_delayed_work_on() on local CPU.
  448. */
  449. static inline bool mod_delayed_work(struct workqueue_struct *wq,
  450. struct delayed_work *dwork,
  451. unsigned long delay)
  452. {
  453. return mod_delayed_work_on(WORK_CPU_UNBOUND, wq, dwork, delay);
  454. }
  455. /**
  456. * schedule_work_on - put work task on a specific cpu
  457. * @cpu: cpu to put the work task on
  458. * @work: job to be done
  459. *
  460. * This puts a job on a specific cpu
  461. */
  462. static inline bool schedule_work_on(int cpu, struct work_struct *work)
  463. {
  464. return queue_work_on(cpu, system_wq, work);
  465. }
  466. /**
  467. * schedule_work - put work task in global workqueue
  468. * @work: job to be done
  469. *
  470. * Returns %false if @work was already on the kernel-global workqueue and
  471. * %true otherwise.
  472. *
  473. * This puts a job in the kernel-global workqueue if it was not already
  474. * queued and leaves it in the same position on the kernel-global
  475. * workqueue otherwise.
  476. */
  477. static inline bool schedule_work(struct work_struct *work)
  478. {
  479. return queue_work(system_wq, work);
  480. }
  481. /**
  482. * flush_scheduled_work - ensure that any scheduled work has run to completion.
  483. *
  484. * Forces execution of the kernel-global workqueue and blocks until its
  485. * completion.
  486. *
  487. * Think twice before calling this function! It's very easy to get into
  488. * trouble if you don't take great care. Either of the following situations
  489. * will lead to deadlock:
  490. *
  491. * One of the work items currently on the workqueue needs to acquire
  492. * a lock held by your code or its caller.
  493. *
  494. * Your code is running in the context of a work routine.
  495. *
  496. * They will be detected by lockdep when they occur, but the first might not
  497. * occur very often. It depends on what work items are on the workqueue and
  498. * what locks they need, which you have no control over.
  499. *
  500. * In most situations flushing the entire workqueue is overkill; you merely
  501. * need to know that a particular work item isn't queued and isn't running.
  502. * In such cases you should use cancel_delayed_work_sync() or
  503. * cancel_work_sync() instead.
  504. */
  505. static inline void flush_scheduled_work(void)
  506. {
  507. flush_workqueue(system_wq);
  508. }
  509. /**
  510. * schedule_delayed_work_on - queue work in global workqueue on CPU after delay
  511. * @cpu: cpu to use
  512. * @dwork: job to be done
  513. * @delay: number of jiffies to wait
  514. *
  515. * After waiting for a given time this puts a job in the kernel-global
  516. * workqueue on the specified CPU.
  517. */
  518. static inline bool schedule_delayed_work_on(int cpu, struct delayed_work *dwork,
  519. unsigned long delay)
  520. {
  521. return queue_delayed_work_on(cpu, system_wq, dwork, delay);
  522. }
  523. /**
  524. * schedule_delayed_work - put work task in global workqueue after delay
  525. * @dwork: job to be done
  526. * @delay: number of jiffies to wait or 0 for immediate execution
  527. *
  528. * After waiting for a given time this puts a job in the kernel-global
  529. * workqueue.
  530. */
  531. static inline bool schedule_delayed_work(struct delayed_work *dwork,
  532. unsigned long delay)
  533. {
  534. return queue_delayed_work(system_wq, dwork, delay);
  535. }
  536. #ifndef CONFIG_SMP
  537. static inline long work_on_cpu(int cpu, long (*fn)(void *), void *arg)
  538. {
  539. return fn(arg);
  540. }
  541. static inline long work_on_cpu_safe(int cpu, long (*fn)(void *), void *arg)
  542. {
  543. return fn(arg);
  544. }
  545. #else
  546. long work_on_cpu(int cpu, long (*fn)(void *), void *arg);
  547. long work_on_cpu_safe(int cpu, long (*fn)(void *), void *arg);
  548. #endif /* CONFIG_SMP */
  549. #ifdef CONFIG_FREEZER
  550. extern void freeze_workqueues_begin(void);
  551. extern bool freeze_workqueues_busy(void);
  552. extern void thaw_workqueues(void);
  553. #endif /* CONFIG_FREEZER */
  554. #ifdef CONFIG_SYSFS
  555. int workqueue_sysfs_register(struct workqueue_struct *wq);
  556. #else /* CONFIG_SYSFS */
  557. static inline int workqueue_sysfs_register(struct workqueue_struct *wq)
  558. { return 0; }
  559. #endif /* CONFIG_SYSFS */
  560. #ifdef CONFIG_WQ_WATCHDOG
  561. void wq_watchdog_touch(int cpu);
  562. #else /* CONFIG_WQ_WATCHDOG */
  563. static inline void wq_watchdog_touch(int cpu) { }
  564. #endif /* CONFIG_WQ_WATCHDOG */
  565. #ifdef CONFIG_SMP
  566. int workqueue_prepare_cpu(unsigned int cpu);
  567. int workqueue_online_cpu(unsigned int cpu);
  568. int workqueue_offline_cpu(unsigned int cpu);
  569. #endif
  570. int __init workqueue_init_early(void);
  571. int __init workqueue_init(void);
  572. #endif