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TOMOYO Linux Cross Reference
Linux/include/linux/workqueue.h

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  1 /* SPDX-License-Identifier: GPL-2.0 */
  2 /*
  3  * workqueue.h --- work queue handling for Linux.
  4  */
  5 
  6 #ifndef _LINUX_WORKQUEUE_H
  7 #define _LINUX_WORKQUEUE_H
  8 
  9 #include <linux/timer.h>
 10 #include <linux/linkage.h>
 11 #include <linux/bitops.h>
 12 #include <linux/lockdep.h>
 13 #include <linux/threads.h>
 14 #include <linux/atomic.h>
 15 #include <linux/cpumask.h>
 16 #include <linux/rcupdate.h>
 17 
 18 struct workqueue_struct;
 19 
 20 struct work_struct;
 21 typedef void (*work_func_t)(struct work_struct *work);
 22 void delayed_work_timer_fn(struct timer_list *t);
 23 
 24 /*
 25  * The first word is the work queue pointer and the flags rolled into
 26  * one
 27  */
 28 #define work_data_bits(work) ((unsigned long *)(&(work)->data))
 29 
 30 enum {
 31         WORK_STRUCT_PENDING_BIT = 0,    /* work item is pending execution */
 32         WORK_STRUCT_DELAYED_BIT = 1,    /* work item is delayed */
 33         WORK_STRUCT_PWQ_BIT     = 2,    /* data points to pwq */
 34         WORK_STRUCT_LINKED_BIT  = 3,    /* next work is linked to this one */
 35 #ifdef CONFIG_DEBUG_OBJECTS_WORK
 36         WORK_STRUCT_STATIC_BIT  = 4,    /* static initializer (debugobjects) */
 37         WORK_STRUCT_COLOR_SHIFT = 5,    /* color for workqueue flushing */
 38 #else
 39         WORK_STRUCT_COLOR_SHIFT = 4,    /* color for workqueue flushing */
 40 #endif
 41 
 42         WORK_STRUCT_COLOR_BITS  = 4,
 43 
 44         WORK_STRUCT_PENDING     = 1 << WORK_STRUCT_PENDING_BIT,
 45         WORK_STRUCT_DELAYED     = 1 << WORK_STRUCT_DELAYED_BIT,
 46         WORK_STRUCT_PWQ         = 1 << WORK_STRUCT_PWQ_BIT,
 47         WORK_STRUCT_LINKED      = 1 << WORK_STRUCT_LINKED_BIT,
 48 #ifdef CONFIG_DEBUG_OBJECTS_WORK
 49         WORK_STRUCT_STATIC      = 1 << WORK_STRUCT_STATIC_BIT,
 50 #else
 51         WORK_STRUCT_STATIC      = 0,
 52 #endif
 53 
 54         /*
 55          * The last color is no color used for works which don't
 56          * participate in workqueue flushing.
 57          */
 58         WORK_NR_COLORS          = (1 << WORK_STRUCT_COLOR_BITS) - 1,
 59         WORK_NO_COLOR           = WORK_NR_COLORS,
 60 
 61         /* not bound to any CPU, prefer the local CPU */
 62         WORK_CPU_UNBOUND        = NR_CPUS,
 63 
 64         /*
 65          * Reserve 7 bits off of pwq pointer w/ debugobjects turned off.
 66          * This makes pwqs aligned to 256 bytes and allows 15 workqueue
 67          * flush colors.
 68          */
 69         WORK_STRUCT_FLAG_BITS   = WORK_STRUCT_COLOR_SHIFT +
 70                                   WORK_STRUCT_COLOR_BITS,
 71 
 72         /* data contains off-queue information when !WORK_STRUCT_PWQ */
 73         WORK_OFFQ_FLAG_BASE     = WORK_STRUCT_COLOR_SHIFT,
 74 
 75         __WORK_OFFQ_CANCELING   = WORK_OFFQ_FLAG_BASE,
 76         WORK_OFFQ_CANCELING     = (1 << __WORK_OFFQ_CANCELING),
 77 
 78         /*
 79          * When a work item is off queue, its high bits point to the last
 80          * pool it was on.  Cap at 31 bits and use the highest number to
 81          * indicate that no pool is associated.
 82          */
 83         WORK_OFFQ_FLAG_BITS     = 1,
 84         WORK_OFFQ_POOL_SHIFT    = WORK_OFFQ_FLAG_BASE + WORK_OFFQ_FLAG_BITS,
 85         WORK_OFFQ_LEFT          = BITS_PER_LONG - WORK_OFFQ_POOL_SHIFT,
 86         WORK_OFFQ_POOL_BITS     = WORK_OFFQ_LEFT <= 31 ? WORK_OFFQ_LEFT : 31,
 87         WORK_OFFQ_POOL_NONE     = (1LU << WORK_OFFQ_POOL_BITS) - 1,
 88 
 89         /* convenience constants */
 90         WORK_STRUCT_FLAG_MASK   = (1UL << WORK_STRUCT_FLAG_BITS) - 1,
 91         WORK_STRUCT_WQ_DATA_MASK = ~WORK_STRUCT_FLAG_MASK,
 92         WORK_STRUCT_NO_POOL     = (unsigned long)WORK_OFFQ_POOL_NONE << WORK_OFFQ_POOL_SHIFT,
 93 
 94         /* bit mask for work_busy() return values */
 95         WORK_BUSY_PENDING       = 1 << 0,
 96         WORK_BUSY_RUNNING       = 1 << 1,
 97 
 98         /* maximum string length for set_worker_desc() */
 99         WORKER_DESC_LEN         = 24,
100 };
101 
102 struct work_struct {
103         atomic_long_t data;
104         struct list_head entry;
105         work_func_t func;
106 #ifdef CONFIG_LOCKDEP
107         struct lockdep_map lockdep_map;
108 #endif
109 };
110 
111 #define WORK_DATA_INIT()        ATOMIC_LONG_INIT((unsigned long)WORK_STRUCT_NO_POOL)
112 #define WORK_DATA_STATIC_INIT() \
113         ATOMIC_LONG_INIT((unsigned long)(WORK_STRUCT_NO_POOL | WORK_STRUCT_STATIC))
114 
115 struct delayed_work {
116         struct work_struct work;
117         struct timer_list timer;
118 
119         /* target workqueue and CPU ->timer uses to queue ->work */
120         struct workqueue_struct *wq;
121         int cpu;
122 };
123 
124 struct rcu_work {
125         struct work_struct work;
126         struct rcu_head rcu;
127 
128         /* target workqueue ->rcu uses to queue ->work */
129         struct workqueue_struct *wq;
130 };
131 
132 /**
133  * struct workqueue_attrs - A struct for workqueue attributes.
134  *
135  * This can be used to change attributes of an unbound workqueue.
136  */
137 struct workqueue_attrs {
138         /**
139          * @nice: nice level
140          */
141         int nice;
142 
143         /**
144          * @cpumask: allowed CPUs
145          */
146         cpumask_var_t cpumask;
147 
148         /**
149          * @no_numa: disable NUMA affinity
150          *
151          * Unlike other fields, ``no_numa`` isn't a property of a worker_pool. It
152          * only modifies how :c:func:`apply_workqueue_attrs` select pools and thus
153          * doesn't participate in pool hash calculations or equality comparisons.
154          */
155         bool no_numa;
156 };
157 
158 static inline struct delayed_work *to_delayed_work(struct work_struct *work)
159 {
160         return container_of(work, struct delayed_work, work);
161 }
162 
163 static inline struct rcu_work *to_rcu_work(struct work_struct *work)
164 {
165         return container_of(work, struct rcu_work, work);
166 }
167 
168 struct execute_work {
169         struct work_struct work;
170 };
171 
172 #ifdef CONFIG_LOCKDEP
173 /*
174  * NB: because we have to copy the lockdep_map, setting _key
175  * here is required, otherwise it could get initialised to the
176  * copy of the lockdep_map!
177  */
178 #define __WORK_INIT_LOCKDEP_MAP(n, k) \
179         .lockdep_map = STATIC_LOCKDEP_MAP_INIT(n, k),
180 #else
181 #define __WORK_INIT_LOCKDEP_MAP(n, k)
182 #endif
183 
184 #define __WORK_INITIALIZER(n, f) {                                      \
185         .data = WORK_DATA_STATIC_INIT(),                                \
186         .entry  = { &(n).entry, &(n).entry },                           \
187         .func = (f),                                                    \
188         __WORK_INIT_LOCKDEP_MAP(#n, &(n))                               \
189         }
190 
191 #define __DELAYED_WORK_INITIALIZER(n, f, tflags) {                      \
192         .work = __WORK_INITIALIZER((n).work, (f)),                      \
193         .timer = __TIMER_INITIALIZER(delayed_work_timer_fn,\
194                                      (tflags) | TIMER_IRQSAFE),         \
195         }
196 
197 #define DECLARE_WORK(n, f)                                              \
198         struct work_struct n = __WORK_INITIALIZER(n, f)
199 
200 #define DECLARE_DELAYED_WORK(n, f)                                      \
201         struct delayed_work n = __DELAYED_WORK_INITIALIZER(n, f, 0)
202 
203 #define DECLARE_DEFERRABLE_WORK(n, f)                                   \
204         struct delayed_work n = __DELAYED_WORK_INITIALIZER(n, f, TIMER_DEFERRABLE)
205 
206 #ifdef CONFIG_DEBUG_OBJECTS_WORK
207 extern void __init_work(struct work_struct *work, int onstack);
208 extern void destroy_work_on_stack(struct work_struct *work);
209 extern void destroy_delayed_work_on_stack(struct delayed_work *work);
210 static inline unsigned int work_static(struct work_struct *work)
211 {
212         return *work_data_bits(work) & WORK_STRUCT_STATIC;
213 }
214 #else
215 static inline void __init_work(struct work_struct *work, int onstack) { }
216 static inline void destroy_work_on_stack(struct work_struct *work) { }
217 static inline void destroy_delayed_work_on_stack(struct delayed_work *work) { }
218 static inline unsigned int work_static(struct work_struct *work) { return 0; }
219 #endif
220 
221 /*
222  * initialize all of a work item in one go
223  *
224  * NOTE! No point in using "atomic_long_set()": using a direct
225  * assignment of the work data initializer allows the compiler
226  * to generate better code.
227  */
228 #ifdef CONFIG_LOCKDEP
229 #define __INIT_WORK(_work, _func, _onstack)                             \
230         do {                                                            \
231                 static struct lock_class_key __key;                     \
232                                                                         \
233                 __init_work((_work), _onstack);                         \
234                 (_work)->data = (atomic_long_t) WORK_DATA_INIT();       \
235                 lockdep_init_map(&(_work)->lockdep_map, "(work_completion)"#_work, &__key, 0); \
236                 INIT_LIST_HEAD(&(_work)->entry);                        \
237                 (_work)->func = (_func);                                \
238         } while (0)
239 #else
240 #define __INIT_WORK(_work, _func, _onstack)                             \
241         do {                                                            \
242                 __init_work((_work), _onstack);                         \
243                 (_work)->data = (atomic_long_t) WORK_DATA_INIT();       \
244                 INIT_LIST_HEAD(&(_work)->entry);                        \
245                 (_work)->func = (_func);                                \
246         } while (0)
247 #endif
248 
249 #define INIT_WORK(_work, _func)                                         \
250         __INIT_WORK((_work), (_func), 0)
251 
252 #define INIT_WORK_ONSTACK(_work, _func)                                 \
253         __INIT_WORK((_work), (_func), 1)
254 
255 #define __INIT_DELAYED_WORK(_work, _func, _tflags)                      \
256         do {                                                            \
257                 INIT_WORK(&(_work)->work, (_func));                     \
258                 __init_timer(&(_work)->timer,                           \
259                              delayed_work_timer_fn,                     \
260                              (_tflags) | TIMER_IRQSAFE);                \
261         } while (0)
262 
263 #define __INIT_DELAYED_WORK_ONSTACK(_work, _func, _tflags)              \
264         do {                                                            \
265                 INIT_WORK_ONSTACK(&(_work)->work, (_func));             \
266                 __init_timer_on_stack(&(_work)->timer,                  \
267                                       delayed_work_timer_fn,            \
268                                       (_tflags) | TIMER_IRQSAFE);       \
269         } while (0)
270 
271 #define INIT_DELAYED_WORK(_work, _func)                                 \
272         __INIT_DELAYED_WORK(_work, _func, 0)
273 
274 #define INIT_DELAYED_WORK_ONSTACK(_work, _func)                         \
275         __INIT_DELAYED_WORK_ONSTACK(_work, _func, 0)
276 
277 #define INIT_DEFERRABLE_WORK(_work, _func)                              \
278         __INIT_DELAYED_WORK(_work, _func, TIMER_DEFERRABLE)
279 
280 #define INIT_DEFERRABLE_WORK_ONSTACK(_work, _func)                      \
281         __INIT_DELAYED_WORK_ONSTACK(_work, _func, TIMER_DEFERRABLE)
282 
283 #define INIT_RCU_WORK(_work, _func)                                     \
284         INIT_WORK(&(_work)->work, (_func))
285 
286 #define INIT_RCU_WORK_ONSTACK(_work, _func)                             \
287         INIT_WORK_ONSTACK(&(_work)->work, (_func))
288 
289 /**
290  * work_pending - Find out whether a work item is currently pending
291  * @work: The work item in question
292  */
293 #define work_pending(work) \
294         test_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))
295 
296 /**
297  * delayed_work_pending - Find out whether a delayable work item is currently
298  * pending
299  * @w: The work item in question
300  */
301 #define delayed_work_pending(w) \
302         work_pending(&(w)->work)
303 
304 /*
305  * Workqueue flags and constants.  For details, please refer to
306  * Documentation/core-api/workqueue.rst.
307  */
308 enum {
309         WQ_UNBOUND              = 1 << 1, /* not bound to any cpu */
310         WQ_FREEZABLE            = 1 << 2, /* freeze during suspend */
311         WQ_MEM_RECLAIM          = 1 << 3, /* may be used for memory reclaim */
312         WQ_HIGHPRI              = 1 << 4, /* high priority */
313         WQ_CPU_INTENSIVE        = 1 << 5, /* cpu intensive workqueue */
314         WQ_SYSFS                = 1 << 6, /* visible in sysfs, see wq_sysfs_register() */
315 
316         /*
317          * Per-cpu workqueues are generally preferred because they tend to
318          * show better performance thanks to cache locality.  Per-cpu
319          * workqueues exclude the scheduler from choosing the CPU to
320          * execute the worker threads, which has an unfortunate side effect
321          * of increasing power consumption.
322          *
323          * The scheduler considers a CPU idle if it doesn't have any task
324          * to execute and tries to keep idle cores idle to conserve power;
325          * however, for example, a per-cpu work item scheduled from an
326          * interrupt handler on an idle CPU will force the scheduler to
327          * excute the work item on that CPU breaking the idleness, which in
328          * turn may lead to more scheduling choices which are sub-optimal
329          * in terms of power consumption.
330          *
331          * Workqueues marked with WQ_POWER_EFFICIENT are per-cpu by default
332          * but become unbound if workqueue.power_efficient kernel param is
333          * specified.  Per-cpu workqueues which are identified to
334          * contribute significantly to power-consumption are identified and
335          * marked with this flag and enabling the power_efficient mode
336          * leads to noticeable power saving at the cost of small
337          * performance disadvantage.
338          *
339          * http://thread.gmane.org/gmane.linux.kernel/1480396
340          */
341         WQ_POWER_EFFICIENT      = 1 << 7,
342 
343         __WQ_DRAINING           = 1 << 16, /* internal: workqueue is draining */
344         __WQ_ORDERED            = 1 << 17, /* internal: workqueue is ordered */
345         __WQ_LEGACY             = 1 << 18, /* internal: create*_workqueue() */
346         __WQ_ORDERED_EXPLICIT   = 1 << 19, /* internal: alloc_ordered_workqueue() */
347 
348         WQ_MAX_ACTIVE           = 512,    /* I like 512, better ideas? */
349         WQ_MAX_UNBOUND_PER_CPU  = 4,      /* 4 * #cpus for unbound wq */
350         WQ_DFL_ACTIVE           = WQ_MAX_ACTIVE / 2,
351 };
352 
353 /* unbound wq's aren't per-cpu, scale max_active according to #cpus */
354 #define WQ_UNBOUND_MAX_ACTIVE   \
355         max_t(int, WQ_MAX_ACTIVE, num_possible_cpus() * WQ_MAX_UNBOUND_PER_CPU)
356 
357 /*
358  * System-wide workqueues which are always present.
359  *
360  * system_wq is the one used by schedule[_delayed]_work[_on]().
361  * Multi-CPU multi-threaded.  There are users which expect relatively
362  * short queue flush time.  Don't queue works which can run for too
363  * long.
364  *
365  * system_highpri_wq is similar to system_wq but for work items which
366  * require WQ_HIGHPRI.
367  *
368  * system_long_wq is similar to system_wq but may host long running
369  * works.  Queue flushing might take relatively long.
370  *
371  * system_unbound_wq is unbound workqueue.  Workers are not bound to
372  * any specific CPU, not concurrency managed, and all queued works are
373  * executed immediately as long as max_active limit is not reached and
374  * resources are available.
375  *
376  * system_freezable_wq is equivalent to system_wq except that it's
377  * freezable.
378  *
379  * *_power_efficient_wq are inclined towards saving power and converted
380  * into WQ_UNBOUND variants if 'wq_power_efficient' is enabled; otherwise,
381  * they are same as their non-power-efficient counterparts - e.g.
382  * system_power_efficient_wq is identical to system_wq if
383  * 'wq_power_efficient' is disabled.  See WQ_POWER_EFFICIENT for more info.
384  */
385 extern struct workqueue_struct *system_wq;
386 extern struct workqueue_struct *system_highpri_wq;
387 extern struct workqueue_struct *system_long_wq;
388 extern struct workqueue_struct *system_unbound_wq;
389 extern struct workqueue_struct *system_freezable_wq;
390 extern struct workqueue_struct *system_power_efficient_wq;
391 extern struct workqueue_struct *system_freezable_power_efficient_wq;
392 
393 extern struct workqueue_struct *
394 __alloc_workqueue_key(const char *fmt, unsigned int flags, int max_active,
395         struct lock_class_key *key, const char *lock_name, ...) __printf(1, 6);
396 
397 /**
398  * alloc_workqueue - allocate a workqueue
399  * @fmt: printf format for the name of the workqueue
400  * @flags: WQ_* flags
401  * @max_active: max in-flight work items, 0 for default
402  * @args...: args for @fmt
403  *
404  * Allocate a workqueue with the specified parameters.  For detailed
405  * information on WQ_* flags, please refer to
406  * Documentation/core-api/workqueue.rst.
407  *
408  * The __lock_name macro dance is to guarantee that single lock_class_key
409  * doesn't end up with different namesm, which isn't allowed by lockdep.
410  *
411  * RETURNS:
412  * Pointer to the allocated workqueue on success, %NULL on failure.
413  */
414 #ifdef CONFIG_LOCKDEP
415 #define alloc_workqueue(fmt, flags, max_active, args...)                \
416 ({                                                                      \
417         static struct lock_class_key __key;                             \
418         const char *__lock_name;                                        \
419                                                                         \
420         __lock_name = "(wq_completion)"#fmt#args;                       \
421                                                                         \
422         __alloc_workqueue_key((fmt), (flags), (max_active),             \
423                               &__key, __lock_name, ##args);             \
424 })
425 #else
426 #define alloc_workqueue(fmt, flags, max_active, args...)                \
427         __alloc_workqueue_key((fmt), (flags), (max_active),             \
428                               NULL, NULL, ##args)
429 #endif
430 
431 /**
432  * alloc_ordered_workqueue - allocate an ordered workqueue
433  * @fmt: printf format for the name of the workqueue
434  * @flags: WQ_* flags (only WQ_FREEZABLE and WQ_MEM_RECLAIM are meaningful)
435  * @args...: args for @fmt
436  *
437  * Allocate an ordered workqueue.  An ordered workqueue executes at
438  * most one work item at any given time in the queued order.  They are
439  * implemented as unbound workqueues with @max_active of one.
440  *
441  * RETURNS:
442  * Pointer to the allocated workqueue on success, %NULL on failure.
443  */
444 #define alloc_ordered_workqueue(fmt, flags, args...)                    \
445         alloc_workqueue(fmt, WQ_UNBOUND | __WQ_ORDERED |                \
446                         __WQ_ORDERED_EXPLICIT | (flags), 1, ##args)
447 
448 #define create_workqueue(name)                                          \
449         alloc_workqueue("%s", __WQ_LEGACY | WQ_MEM_RECLAIM, 1, (name))
450 #define create_freezable_workqueue(name)                                \
451         alloc_workqueue("%s", __WQ_LEGACY | WQ_FREEZABLE | WQ_UNBOUND | \
452                         WQ_MEM_RECLAIM, 1, (name))
453 #define create_singlethread_workqueue(name)                             \
454         alloc_ordered_workqueue("%s", __WQ_LEGACY | WQ_MEM_RECLAIM, name)
455 
456 extern void destroy_workqueue(struct workqueue_struct *wq);
457 
458 struct workqueue_attrs *alloc_workqueue_attrs(gfp_t gfp_mask);
459 void free_workqueue_attrs(struct workqueue_attrs *attrs);
460 int apply_workqueue_attrs(struct workqueue_struct *wq,
461                           const struct workqueue_attrs *attrs);
462 int workqueue_set_unbound_cpumask(cpumask_var_t cpumask);
463 
464 extern bool queue_work_on(int cpu, struct workqueue_struct *wq,
465                         struct work_struct *work);
466 extern bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
467                         struct delayed_work *work, unsigned long delay);
468 extern bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq,
469                         struct delayed_work *dwork, unsigned long delay);
470 extern bool queue_rcu_work(struct workqueue_struct *wq, struct rcu_work *rwork);
471 
472 extern void flush_workqueue(struct workqueue_struct *wq);
473 extern void drain_workqueue(struct workqueue_struct *wq);
474 
475 extern int schedule_on_each_cpu(work_func_t func);
476 
477 int execute_in_process_context(work_func_t fn, struct execute_work *);
478 
479 extern bool flush_work(struct work_struct *work);
480 extern bool cancel_work_sync(struct work_struct *work);
481 
482 extern bool flush_delayed_work(struct delayed_work *dwork);
483 extern bool cancel_delayed_work(struct delayed_work *dwork);
484 extern bool cancel_delayed_work_sync(struct delayed_work *dwork);
485 
486 extern bool flush_rcu_work(struct rcu_work *rwork);
487 
488 extern void workqueue_set_max_active(struct workqueue_struct *wq,
489                                      int max_active);
490 extern struct work_struct *current_work(void);
491 extern bool current_is_workqueue_rescuer(void);
492 extern bool workqueue_congested(int cpu, struct workqueue_struct *wq);
493 extern unsigned int work_busy(struct work_struct *work);
494 extern __printf(1, 2) void set_worker_desc(const char *fmt, ...);
495 extern void print_worker_info(const char *log_lvl, struct task_struct *task);
496 extern void show_workqueue_state(void);
497 
498 /**
499  * queue_work - queue work on a workqueue
500  * @wq: workqueue to use
501  * @work: work to queue
502  *
503  * Returns %false if @work was already on a queue, %true otherwise.
504  *
505  * We queue the work to the CPU on which it was submitted, but if the CPU dies
506  * it can be processed by another CPU.
507  */
508 static inline bool queue_work(struct workqueue_struct *wq,
509                               struct work_struct *work)
510 {
511         return queue_work_on(WORK_CPU_UNBOUND, wq, work);
512 }
513 
514 /**
515  * queue_delayed_work - queue work on a workqueue after delay
516  * @wq: workqueue to use
517  * @dwork: delayable work to queue
518  * @delay: number of jiffies to wait before queueing
519  *
520  * Equivalent to queue_delayed_work_on() but tries to use the local CPU.
521  */
522 static inline bool queue_delayed_work(struct workqueue_struct *wq,
523                                       struct delayed_work *dwork,
524                                       unsigned long delay)
525 {
526         return queue_delayed_work_on(WORK_CPU_UNBOUND, wq, dwork, delay);
527 }
528 
529 /**
530  * mod_delayed_work - modify delay of or queue a delayed work
531  * @wq: workqueue to use
532  * @dwork: work to queue
533  * @delay: number of jiffies to wait before queueing
534  *
535  * mod_delayed_work_on() on local CPU.
536  */
537 static inline bool mod_delayed_work(struct workqueue_struct *wq,
538                                     struct delayed_work *dwork,
539                                     unsigned long delay)
540 {
541         return mod_delayed_work_on(WORK_CPU_UNBOUND, wq, dwork, delay);
542 }
543 
544 /**
545  * schedule_work_on - put work task on a specific cpu
546  * @cpu: cpu to put the work task on
547  * @work: job to be done
548  *
549  * This puts a job on a specific cpu
550  */
551 static inline bool schedule_work_on(int cpu, struct work_struct *work)
552 {
553         return queue_work_on(cpu, system_wq, work);
554 }
555 
556 /**
557  * schedule_work - put work task in global workqueue
558  * @work: job to be done
559  *
560  * Returns %false if @work was already on the kernel-global workqueue and
561  * %true otherwise.
562  *
563  * This puts a job in the kernel-global workqueue if it was not already
564  * queued and leaves it in the same position on the kernel-global
565  * workqueue otherwise.
566  */
567 static inline bool schedule_work(struct work_struct *work)
568 {
569         return queue_work(system_wq, work);
570 }
571 
572 /**
573  * flush_scheduled_work - ensure that any scheduled work has run to completion.
574  *
575  * Forces execution of the kernel-global workqueue and blocks until its
576  * completion.
577  *
578  * Think twice before calling this function!  It's very easy to get into
579  * trouble if you don't take great care.  Either of the following situations
580  * will lead to deadlock:
581  *
582  *      One of the work items currently on the workqueue needs to acquire
583  *      a lock held by your code or its caller.
584  *
585  *      Your code is running in the context of a work routine.
586  *
587  * They will be detected by lockdep when they occur, but the first might not
588  * occur very often.  It depends on what work items are on the workqueue and
589  * what locks they need, which you have no control over.
590  *
591  * In most situations flushing the entire workqueue is overkill; you merely
592  * need to know that a particular work item isn't queued and isn't running.
593  * In such cases you should use cancel_delayed_work_sync() or
594  * cancel_work_sync() instead.
595  */
596 static inline void flush_scheduled_work(void)
597 {
598         flush_workqueue(system_wq);
599 }
600 
601 /**
602  * schedule_delayed_work_on - queue work in global workqueue on CPU after delay
603  * @cpu: cpu to use
604  * @dwork: job to be done
605  * @delay: number of jiffies to wait
606  *
607  * After waiting for a given time this puts a job in the kernel-global
608  * workqueue on the specified CPU.
609  */
610 static inline bool schedule_delayed_work_on(int cpu, struct delayed_work *dwork,
611                                             unsigned long delay)
612 {
613         return queue_delayed_work_on(cpu, system_wq, dwork, delay);
614 }
615 
616 /**
617  * schedule_delayed_work - put work task in global workqueue after delay
618  * @dwork: job to be done
619  * @delay: number of jiffies to wait or 0 for immediate execution
620  *
621  * After waiting for a given time this puts a job in the kernel-global
622  * workqueue.
623  */
624 static inline bool schedule_delayed_work(struct delayed_work *dwork,
625                                          unsigned long delay)
626 {
627         return queue_delayed_work(system_wq, dwork, delay);
628 }
629 
630 #ifndef CONFIG_SMP
631 static inline long work_on_cpu(int cpu, long (*fn)(void *), void *arg)
632 {
633         return fn(arg);
634 }
635 static inline long work_on_cpu_safe(int cpu, long (*fn)(void *), void *arg)
636 {
637         return fn(arg);
638 }
639 #else
640 long work_on_cpu(int cpu, long (*fn)(void *), void *arg);
641 long work_on_cpu_safe(int cpu, long (*fn)(void *), void *arg);
642 #endif /* CONFIG_SMP */
643 
644 #ifdef CONFIG_FREEZER
645 extern void freeze_workqueues_begin(void);
646 extern bool freeze_workqueues_busy(void);
647 extern void thaw_workqueues(void);
648 #endif /* CONFIG_FREEZER */
649 
650 #ifdef CONFIG_SYSFS
651 int workqueue_sysfs_register(struct workqueue_struct *wq);
652 #else   /* CONFIG_SYSFS */
653 static inline int workqueue_sysfs_register(struct workqueue_struct *wq)
654 { return 0; }
655 #endif  /* CONFIG_SYSFS */
656 
657 #ifdef CONFIG_WQ_WATCHDOG
658 void wq_watchdog_touch(int cpu);
659 #else   /* CONFIG_WQ_WATCHDOG */
660 static inline void wq_watchdog_touch(int cpu) { }
661 #endif  /* CONFIG_WQ_WATCHDOG */
662 
663 #ifdef CONFIG_SMP
664 int workqueue_prepare_cpu(unsigned int cpu);
665 int workqueue_online_cpu(unsigned int cpu);
666 int workqueue_offline_cpu(unsigned int cpu);
667 #endif
668 
669 int __init workqueue_init_early(void);
670 int __init workqueue_init(void);
671 
672 #endif
673 

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