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

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