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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/alloc_tag.h>
10#include <linux/timer.h>
11#include <linux/linkage.h>
12#include <linux/bitops.h>
13#include <linux/lockdep.h>
14#include <linux/threads.h>
15#include <linux/atomic.h>
16#include <linux/cpumask_types.h>
17#include <linux/rcupdate.h>
18#include <linux/workqueue_types.h>
19
20/*
21 * The first word is the work queue pointer and the flags rolled into
22 * one
23 */
24#define work_data_bits(work) ((unsigned long *)(&(work)->data))
25
26enum work_bits {
27 WORK_STRUCT_PENDING_BIT = 0, /* work item is pending execution */
28 WORK_STRUCT_INACTIVE_BIT, /* work item is inactive */
29 WORK_STRUCT_PWQ_BIT, /* data points to pwq */
30 WORK_STRUCT_LINKED_BIT, /* next work is linked to this one */
31#ifdef CONFIG_DEBUG_OBJECTS_WORK
32 WORK_STRUCT_STATIC_BIT, /* static initializer (debugobjects) */
33#endif
34 WORK_STRUCT_FLAG_BITS,
35
36 /* color for workqueue flushing */
37 WORK_STRUCT_COLOR_SHIFT = WORK_STRUCT_FLAG_BITS,
38 WORK_STRUCT_COLOR_BITS = 4,
39
40 /*
41 * When WORK_STRUCT_PWQ is set, reserve 8 bits off of pwq pointer w/
42 * debugobjects turned off. This makes pwqs aligned to 256 bytes (512
43 * bytes w/ DEBUG_OBJECTS_WORK) and allows 16 workqueue flush colors.
44 *
45 * MSB
46 * [ pwq pointer ] [ flush color ] [ STRUCT flags ]
47 * 4 bits 4 or 5 bits
48 */
49 WORK_STRUCT_PWQ_SHIFT = WORK_STRUCT_COLOR_SHIFT + WORK_STRUCT_COLOR_BITS,
50
51 /*
52 * data contains off-queue information when !WORK_STRUCT_PWQ.
53 *
54 * MSB
55 * [ pool ID ] [ disable depth ] [ OFFQ flags ] [ STRUCT flags ]
56 * 16 bits 1 bit 4 or 5 bits
57 */
58 WORK_OFFQ_FLAG_SHIFT = WORK_STRUCT_FLAG_BITS,
59 WORK_OFFQ_BH_BIT = WORK_OFFQ_FLAG_SHIFT,
60 WORK_OFFQ_FLAG_END,
61 WORK_OFFQ_FLAG_BITS = WORK_OFFQ_FLAG_END - WORK_OFFQ_FLAG_SHIFT,
62
63 WORK_OFFQ_DISABLE_SHIFT = WORK_OFFQ_FLAG_SHIFT + WORK_OFFQ_FLAG_BITS,
64 WORK_OFFQ_DISABLE_BITS = 16,
65
66 /*
67 * When a work item is off queue, the high bits encode off-queue flags
68 * and the last pool it was on. Cap pool ID to 31 bits and use the
69 * highest number to indicate that no pool is associated.
70 */
71 WORK_OFFQ_POOL_SHIFT = WORK_OFFQ_DISABLE_SHIFT + WORK_OFFQ_DISABLE_BITS,
72 WORK_OFFQ_LEFT = BITS_PER_LONG - WORK_OFFQ_POOL_SHIFT,
73 WORK_OFFQ_POOL_BITS = WORK_OFFQ_LEFT <= 31 ? WORK_OFFQ_LEFT : 31,
74};
75
76enum work_flags {
77 WORK_STRUCT_PENDING = 1 << WORK_STRUCT_PENDING_BIT,
78 WORK_STRUCT_INACTIVE = 1 << WORK_STRUCT_INACTIVE_BIT,
79 WORK_STRUCT_PWQ = 1 << WORK_STRUCT_PWQ_BIT,
80 WORK_STRUCT_LINKED = 1 << WORK_STRUCT_LINKED_BIT,
81#ifdef CONFIG_DEBUG_OBJECTS_WORK
82 WORK_STRUCT_STATIC = 1 << WORK_STRUCT_STATIC_BIT,
83#else
84 WORK_STRUCT_STATIC = 0,
85#endif
86};
87
88enum wq_misc_consts {
89 WORK_NR_COLORS = (1 << WORK_STRUCT_COLOR_BITS),
90
91 /* not bound to any CPU, prefer the local CPU */
92 WORK_CPU_UNBOUND = NR_CPUS,
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 = 32,
100};
101
102/* Convenience constants - of type 'unsigned long', not 'enum'! */
103#define WORK_OFFQ_BH (1ul << WORK_OFFQ_BH_BIT)
104#define WORK_OFFQ_FLAG_MASK (((1ul << WORK_OFFQ_FLAG_BITS) - 1) << WORK_OFFQ_FLAG_SHIFT)
105#define WORK_OFFQ_DISABLE_MASK (((1ul << WORK_OFFQ_DISABLE_BITS) - 1) << WORK_OFFQ_DISABLE_SHIFT)
106#define WORK_OFFQ_POOL_NONE ((1ul << WORK_OFFQ_POOL_BITS) - 1)
107#define WORK_STRUCT_NO_POOL (WORK_OFFQ_POOL_NONE << WORK_OFFQ_POOL_SHIFT)
108#define WORK_STRUCT_PWQ_MASK (~((1ul << WORK_STRUCT_PWQ_SHIFT) - 1))
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
114struct 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
123struct rcu_work {
124 struct work_struct work;
125 struct rcu_head rcu;
126
127 /* target workqueue ->rcu uses to queue ->work */
128 struct workqueue_struct *wq;
129};
130
131enum wq_affn_scope {
132 WQ_AFFN_DFL, /* use system default */
133 WQ_AFFN_CPU, /* one pod per CPU */
134 WQ_AFFN_SMT, /* one pod poer SMT */
135 WQ_AFFN_CACHE, /* one pod per LLC */
136 WQ_AFFN_NUMA, /* one pod per NUMA node */
137 WQ_AFFN_SYSTEM, /* one pod across the whole system */
138
139 WQ_AFFN_NR_TYPES,
140};
141
142/**
143 * struct workqueue_attrs - A struct for workqueue attributes.
144 *
145 * This can be used to change attributes of an unbound workqueue.
146 */
147struct workqueue_attrs {
148 /**
149 * @nice: nice level
150 */
151 int nice;
152
153 /**
154 * @cpumask: allowed CPUs
155 *
156 * Work items in this workqueue are affine to these CPUs and not allowed
157 * to execute on other CPUs. A pool serving a workqueue must have the
158 * same @cpumask.
159 */
160 cpumask_var_t cpumask;
161
162 /**
163 * @__pod_cpumask: internal attribute used to create per-pod pools
164 *
165 * Internal use only.
166 *
167 * Per-pod unbound worker pools are used to improve locality. Always a
168 * subset of ->cpumask. A workqueue can be associated with multiple
169 * worker pools with disjoint @__pod_cpumask's. Whether the enforcement
170 * of a pool's @__pod_cpumask is strict depends on @affn_strict.
171 */
172 cpumask_var_t __pod_cpumask;
173
174 /**
175 * @affn_strict: affinity scope is strict
176 *
177 * If clear, workqueue will make a best-effort attempt at starting the
178 * worker inside @__pod_cpumask but the scheduler is free to migrate it
179 * outside.
180 *
181 * If set, workers are only allowed to run inside @__pod_cpumask.
182 */
183 bool affn_strict;
184
185 /*
186 * Below fields aren't properties of a worker_pool. They only modify how
187 * :c:func:`apply_workqueue_attrs` select pools and thus don't
188 * participate in pool hash calculations or equality comparisons.
189 *
190 * If @affn_strict is set, @cpumask isn't a property of a worker_pool
191 * either.
192 */
193
194 /**
195 * @affn_scope: unbound CPU affinity scope
196 *
197 * CPU pods are used to improve execution locality of unbound work
198 * items. There are multiple pod types, one for each wq_affn_scope, and
199 * every CPU in the system belongs to one pod in every pod type. CPUs
200 * that belong to the same pod share the worker pool. For example,
201 * selecting %WQ_AFFN_NUMA makes the workqueue use a separate worker
202 * pool for each NUMA node.
203 */
204 enum wq_affn_scope affn_scope;
205
206 /**
207 * @ordered: work items must be executed one by one in queueing order
208 */
209 bool ordered;
210};
211
212static inline struct delayed_work *to_delayed_work(struct work_struct *work)
213{
214 return container_of(work, struct delayed_work, work);
215}
216
217static inline struct rcu_work *to_rcu_work(struct work_struct *work)
218{
219 return container_of(work, struct rcu_work, work);
220}
221
222struct execute_work {
223 struct work_struct work;
224};
225
226#ifdef CONFIG_LOCKDEP
227/*
228 * NB: because we have to copy the lockdep_map, setting _key
229 * here is required, otherwise it could get initialised to the
230 * copy of the lockdep_map!
231 */
232#define __WORK_INIT_LOCKDEP_MAP(n, k) \
233 .lockdep_map = STATIC_LOCKDEP_MAP_INIT(n, k),
234#else
235#define __WORK_INIT_LOCKDEP_MAP(n, k)
236#endif
237
238#define __WORK_INITIALIZER(n, f) { \
239 .data = WORK_DATA_STATIC_INIT(), \
240 .entry = { &(n).entry, &(n).entry }, \
241 .func = (f), \
242 __WORK_INIT_LOCKDEP_MAP(#n, &(n)) \
243 }
244
245#define __DELAYED_WORK_INITIALIZER(n, f, tflags) { \
246 .work = __WORK_INITIALIZER((n).work, (f)), \
247 .timer = __TIMER_INITIALIZER(delayed_work_timer_fn,\
248 (tflags) | TIMER_IRQSAFE), \
249 }
250
251#define DECLARE_WORK(n, f) \
252 struct work_struct n = __WORK_INITIALIZER(n, f)
253
254#define DECLARE_DELAYED_WORK(n, f) \
255 struct delayed_work n = __DELAYED_WORK_INITIALIZER(n, f, 0)
256
257#define DECLARE_DEFERRABLE_WORK(n, f) \
258 struct delayed_work n = __DELAYED_WORK_INITIALIZER(n, f, TIMER_DEFERRABLE)
259
260#ifdef CONFIG_DEBUG_OBJECTS_WORK
261extern void __init_work(struct work_struct *work, int onstack);
262extern void destroy_work_on_stack(struct work_struct *work);
263extern void destroy_delayed_work_on_stack(struct delayed_work *work);
264static inline unsigned int work_static(struct work_struct *work)
265{
266 return *work_data_bits(work) & WORK_STRUCT_STATIC;
267}
268#else
269static inline void __init_work(struct work_struct *work, int onstack) { }
270static inline void destroy_work_on_stack(struct work_struct *work) { }
271static inline void destroy_delayed_work_on_stack(struct delayed_work *work) { }
272static inline unsigned int work_static(struct work_struct *work) { return 0; }
273#endif
274
275/*
276 * initialize all of a work item in one go
277 *
278 * NOTE! No point in using "atomic_long_set()": using a direct
279 * assignment of the work data initializer allows the compiler
280 * to generate better code.
281 */
282#ifdef CONFIG_LOCKDEP
283#define __INIT_WORK_KEY(_work, _func, _onstack, _key) \
284 do { \
285 __init_work((_work), _onstack); \
286 (_work)->data = (atomic_long_t) WORK_DATA_INIT(); \
287 lockdep_init_map(&(_work)->lockdep_map, "(work_completion)"#_work, (_key), 0); \
288 INIT_LIST_HEAD(&(_work)->entry); \
289 (_work)->func = (_func); \
290 } while (0)
291#else
292#define __INIT_WORK_KEY(_work, _func, _onstack, _key) \
293 do { \
294 __init_work((_work), _onstack); \
295 (_work)->data = (atomic_long_t) WORK_DATA_INIT(); \
296 INIT_LIST_HEAD(&(_work)->entry); \
297 (_work)->func = (_func); \
298 } while (0)
299#endif
300
301#define __INIT_WORK(_work, _func, _onstack) \
302 do { \
303 static __maybe_unused struct lock_class_key __key; \
304 \
305 __INIT_WORK_KEY(_work, _func, _onstack, &__key); \
306 } while (0)
307
308#define INIT_WORK(_work, _func) \
309 __INIT_WORK((_work), (_func), 0)
310
311#define INIT_WORK_ONSTACK(_work, _func) \
312 __INIT_WORK((_work), (_func), 1)
313
314#define INIT_WORK_ONSTACK_KEY(_work, _func, _key) \
315 __INIT_WORK_KEY((_work), (_func), 1, _key)
316
317#define __INIT_DELAYED_WORK(_work, _func, _tflags) \
318 do { \
319 INIT_WORK(&(_work)->work, (_func)); \
320 __timer_init(&(_work)->timer, \
321 delayed_work_timer_fn, \
322 (_tflags) | TIMER_IRQSAFE); \
323 } while (0)
324
325#define __INIT_DELAYED_WORK_ONSTACK(_work, _func, _tflags) \
326 do { \
327 INIT_WORK_ONSTACK(&(_work)->work, (_func)); \
328 __timer_init_on_stack(&(_work)->timer, \
329 delayed_work_timer_fn, \
330 (_tflags) | TIMER_IRQSAFE); \
331 } while (0)
332
333#define INIT_DELAYED_WORK(_work, _func) \
334 __INIT_DELAYED_WORK(_work, _func, 0)
335
336#define INIT_DELAYED_WORK_ONSTACK(_work, _func) \
337 __INIT_DELAYED_WORK_ONSTACK(_work, _func, 0)
338
339#define INIT_DEFERRABLE_WORK(_work, _func) \
340 __INIT_DELAYED_WORK(_work, _func, TIMER_DEFERRABLE)
341
342#define INIT_DEFERRABLE_WORK_ONSTACK(_work, _func) \
343 __INIT_DELAYED_WORK_ONSTACK(_work, _func, TIMER_DEFERRABLE)
344
345#define INIT_RCU_WORK(_work, _func) \
346 INIT_WORK(&(_work)->work, (_func))
347
348#define INIT_RCU_WORK_ONSTACK(_work, _func) \
349 INIT_WORK_ONSTACK(&(_work)->work, (_func))
350
351/**
352 * work_pending - Find out whether a work item is currently pending
353 * @work: The work item in question
354 */
355#define work_pending(work) \
356 test_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))
357
358/**
359 * delayed_work_pending - Find out whether a delayable work item is currently
360 * pending
361 * @w: The work item in question
362 */
363#define delayed_work_pending(w) \
364 work_pending(&(w)->work)
365
366/*
367 * Workqueue flags and constants. For details, please refer to
368 * Documentation/core-api/workqueue.rst.
369 */
370enum wq_flags {
371 WQ_BH = 1 << 0, /* execute in bottom half (softirq) context */
372 WQ_UNBOUND = 1 << 1, /* not bound to any cpu */
373 WQ_FREEZABLE = 1 << 2, /* freeze during suspend */
374 WQ_MEM_RECLAIM = 1 << 3, /* may be used for memory reclaim */
375 WQ_HIGHPRI = 1 << 4, /* high priority */
376 WQ_CPU_INTENSIVE = 1 << 5, /* cpu intensive workqueue */
377 WQ_SYSFS = 1 << 6, /* visible in sysfs, see workqueue_sysfs_register() */
378
379 /*
380 * Per-cpu workqueues are generally preferred because they tend to
381 * show better performance thanks to cache locality. Per-cpu
382 * workqueues exclude the scheduler from choosing the CPU to
383 * execute the worker threads, which has an unfortunate side effect
384 * of increasing power consumption.
385 *
386 * The scheduler considers a CPU idle if it doesn't have any task
387 * to execute and tries to keep idle cores idle to conserve power;
388 * however, for example, a per-cpu work item scheduled from an
389 * interrupt handler on an idle CPU will force the scheduler to
390 * execute the work item on that CPU breaking the idleness, which in
391 * turn may lead to more scheduling choices which are sub-optimal
392 * in terms of power consumption.
393 *
394 * Workqueues marked with WQ_POWER_EFFICIENT are per-cpu by default
395 * but become unbound if workqueue.power_efficient kernel param is
396 * specified. Per-cpu workqueues which are identified to
397 * contribute significantly to power-consumption are identified and
398 * marked with this flag and enabling the power_efficient mode
399 * leads to noticeable power saving at the cost of small
400 * performance disadvantage.
401 *
402 * http://thread.gmane.org/gmane.linux.kernel/1480396
403 */
404 WQ_POWER_EFFICIENT = 1 << 7,
405 WQ_PERCPU = 1 << 8, /* bound to a specific cpu */
406
407 __WQ_DESTROYING = 1 << 15, /* internal: workqueue is destroying */
408 __WQ_DRAINING = 1 << 16, /* internal: workqueue is draining */
409 __WQ_ORDERED = 1 << 17, /* internal: workqueue is ordered */
410 __WQ_LEGACY = 1 << 18, /* internal: create*_workqueue() */
411
412 /* BH wq only allows the following flags */
413 __WQ_BH_ALLOWS = WQ_BH | WQ_HIGHPRI | WQ_PERCPU,
414};
415
416enum wq_consts {
417 WQ_MAX_ACTIVE = 2048, /* I like 2048, better ideas? */
418 WQ_UNBOUND_MAX_ACTIVE = WQ_MAX_ACTIVE,
419 WQ_DFL_ACTIVE = WQ_MAX_ACTIVE / 2,
420
421 /*
422 * Per-node default cap on min_active. Unless explicitly set, min_active
423 * is set to min(max_active, WQ_DFL_MIN_ACTIVE). For more details, see
424 * workqueue_struct->min_active definition.
425 */
426 WQ_DFL_MIN_ACTIVE = 8,
427};
428
429/*
430 * System-wide workqueues which are always present.
431 *
432 * system_percpu_wq is the one used by schedule[_delayed]_work[_on]().
433 * Multi-CPU multi-threaded. There are users which expect relatively
434 * short queue flush time. Don't queue works which can run for too
435 * long.
436 *
437 * system_highpri_wq is similar to system_percpu_wq but for work items which
438 * require WQ_HIGHPRI.
439 *
440 * system_long_wq is similar to system_percpu_wq but may host long running
441 * works. Queue flushing might take relatively long.
442 *
443 * system_dfl_wq is unbound workqueue. Workers are not bound to
444 * any specific CPU, not concurrency managed, and all queued works are
445 * executed immediately as long as max_active limit is not reached and
446 * resources are available.
447 *
448 * system_freezable_wq is equivalent to system_percpu_wq except that it's
449 * freezable.
450 *
451 * *_power_efficient_wq are inclined towards saving power and converted
452 * into WQ_UNBOUND variants if 'wq_power_efficient' is enabled; otherwise,
453 * they are same as their non-power-efficient counterparts - e.g.
454 * system_power_efficient_wq is identical to system_percpu_wq if
455 * 'wq_power_efficient' is disabled. See WQ_POWER_EFFICIENT for more info.
456 *
457 * system_bh[_highpri]_wq are convenience interface to softirq. BH work items
458 * are executed in the queueing CPU's BH context in the queueing order.
459 */
460extern struct workqueue_struct *system_wq; /* use system_percpu_wq, this will be removed */
461extern struct workqueue_struct *system_percpu_wq;
462extern struct workqueue_struct *system_highpri_wq;
463extern struct workqueue_struct *system_long_wq;
464extern struct workqueue_struct *system_unbound_wq;
465extern struct workqueue_struct *system_dfl_wq;
466extern struct workqueue_struct *system_freezable_wq;
467extern struct workqueue_struct *system_power_efficient_wq;
468extern struct workqueue_struct *system_freezable_power_efficient_wq;
469extern struct workqueue_struct *system_bh_wq;
470extern struct workqueue_struct *system_bh_highpri_wq;
471
472void workqueue_softirq_action(bool highpri);
473void workqueue_softirq_dead(unsigned int cpu);
474
475/**
476 * alloc_workqueue - allocate a workqueue
477 * @fmt: printf format for the name of the workqueue
478 * @flags: WQ_* flags
479 * @max_active: max in-flight work items, 0 for default
480 * @...: args for @fmt
481 *
482 * For a per-cpu workqueue, @max_active limits the number of in-flight work
483 * items for each CPU. e.g. @max_active of 1 indicates that each CPU can be
484 * executing at most one work item for the workqueue.
485 *
486 * For unbound workqueues, @max_active limits the number of in-flight work items
487 * for the whole system. e.g. @max_active of 16 indicates that there can be
488 * at most 16 work items executing for the workqueue in the whole system.
489 *
490 * As sharing the same active counter for an unbound workqueue across multiple
491 * NUMA nodes can be expensive, @max_active is distributed to each NUMA node
492 * according to the proportion of the number of online CPUs and enforced
493 * independently.
494 *
495 * Depending on online CPU distribution, a node may end up with per-node
496 * max_active which is significantly lower than @max_active, which can lead to
497 * deadlocks if the per-node concurrency limit is lower than the maximum number
498 * of interdependent work items for the workqueue.
499 *
500 * To guarantee forward progress regardless of online CPU distribution, the
501 * concurrency limit on every node is guaranteed to be equal to or greater than
502 * min_active which is set to min(@max_active, %WQ_DFL_MIN_ACTIVE). This means
503 * that the sum of per-node max_active's may be larger than @max_active.
504 *
505 * For detailed information on %WQ_\* flags, please refer to
506 * Documentation/core-api/workqueue.rst.
507 *
508 * RETURNS:
509 * Pointer to the allocated workqueue on success, %NULL on failure.
510 */
511__printf(1, 4) struct workqueue_struct *
512alloc_workqueue_noprof(const char *fmt, unsigned int flags, int max_active, ...);
513#define alloc_workqueue(...) alloc_hooks(alloc_workqueue_noprof(__VA_ARGS__))
514
515#ifdef CONFIG_LOCKDEP
516/**
517 * alloc_workqueue_lockdep_map - allocate a workqueue with user-defined lockdep_map
518 * @fmt: printf format for the name of the workqueue
519 * @flags: WQ_* flags
520 * @max_active: max in-flight work items, 0 for default
521 * @lockdep_map: user-defined lockdep_map
522 * @...: args for @fmt
523 *
524 * Same as alloc_workqueue but with the a user-define lockdep_map. Useful for
525 * workqueues created with the same purpose and to avoid leaking a lockdep_map
526 * on each workqueue creation.
527 *
528 * RETURNS:
529 * Pointer to the allocated workqueue on success, %NULL on failure.
530 */
531__printf(1, 5) struct workqueue_struct *
532alloc_workqueue_lockdep_map(const char *fmt, unsigned int flags, int max_active,
533 struct lockdep_map *lockdep_map, ...);
534
535/**
536 * alloc_ordered_workqueue_lockdep_map - allocate an ordered workqueue with
537 * user-defined lockdep_map
538 *
539 * @fmt: printf format for the name of the workqueue
540 * @flags: WQ_* flags (only WQ_FREEZABLE and WQ_MEM_RECLAIM are meaningful)
541 * @lockdep_map: user-defined lockdep_map
542 * @args: args for @fmt
543 *
544 * Same as alloc_ordered_workqueue but with the a user-define lockdep_map.
545 * Useful for workqueues created with the same purpose and to avoid leaking a
546 * lockdep_map on each workqueue creation.
547 *
548 * RETURNS:
549 * Pointer to the allocated workqueue on success, %NULL on failure.
550 */
551#define alloc_ordered_workqueue_lockdep_map(fmt, flags, lockdep_map, args...) \
552 alloc_hooks(alloc_workqueue_lockdep_map(fmt, WQ_UNBOUND | __WQ_ORDERED | (flags),\
553 1, lockdep_map, ##args))
554#endif
555
556/**
557 * alloc_ordered_workqueue - allocate an ordered workqueue
558 * @fmt: printf format for the name of the workqueue
559 * @flags: WQ_* flags (only WQ_FREEZABLE and WQ_MEM_RECLAIM are meaningful)
560 * @args: args for @fmt
561 *
562 * Allocate an ordered workqueue. An ordered workqueue executes at
563 * most one work item at any given time in the queued order. They are
564 * implemented as unbound workqueues with @max_active of one.
565 *
566 * RETURNS:
567 * Pointer to the allocated workqueue on success, %NULL on failure.
568 */
569#define alloc_ordered_workqueue(fmt, flags, args...) \
570 alloc_workqueue(fmt, WQ_UNBOUND | __WQ_ORDERED | (flags), 1, ##args)
571
572#define create_workqueue(name) \
573 alloc_workqueue("%s", __WQ_LEGACY | WQ_MEM_RECLAIM | WQ_PERCPU, 1, (name))
574#define create_freezable_workqueue(name) \
575 alloc_workqueue("%s", __WQ_LEGACY | WQ_FREEZABLE | WQ_UNBOUND | \
576 WQ_MEM_RECLAIM, 1, (name))
577#define create_singlethread_workqueue(name) \
578 alloc_ordered_workqueue("%s", __WQ_LEGACY | WQ_MEM_RECLAIM, name)
579
580#define from_work(var, callback_work, work_fieldname) \
581 container_of(callback_work, typeof(*var), work_fieldname)
582
583extern void destroy_workqueue(struct workqueue_struct *wq);
584
585struct workqueue_attrs *alloc_workqueue_attrs_noprof(void);
586#define alloc_workqueue_attrs(...) alloc_hooks(alloc_workqueue_attrs_noprof(__VA_ARGS__))
587
588void free_workqueue_attrs(struct workqueue_attrs *attrs);
589int apply_workqueue_attrs(struct workqueue_struct *wq,
590 const struct workqueue_attrs *attrs);
591extern int workqueue_unbound_exclude_cpumask(cpumask_var_t cpumask);
592
593extern bool queue_work_on(int cpu, struct workqueue_struct *wq,
594 struct work_struct *work);
595extern bool queue_work_node(int node, struct workqueue_struct *wq,
596 struct work_struct *work);
597extern bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
598 struct delayed_work *work, unsigned long delay);
599extern bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq,
600 struct delayed_work *dwork, unsigned long delay);
601extern bool queue_rcu_work(struct workqueue_struct *wq, struct rcu_work *rwork);
602
603extern void __flush_workqueue(struct workqueue_struct *wq);
604extern void drain_workqueue(struct workqueue_struct *wq);
605
606extern int schedule_on_each_cpu(work_func_t func);
607
608int execute_in_process_context(work_func_t fn, struct execute_work *);
609
610extern bool flush_work(struct work_struct *work);
611extern bool cancel_work(struct work_struct *work);
612extern bool cancel_work_sync(struct work_struct *work);
613
614extern bool flush_delayed_work(struct delayed_work *dwork);
615extern bool cancel_delayed_work(struct delayed_work *dwork);
616extern bool cancel_delayed_work_sync(struct delayed_work *dwork);
617
618extern bool disable_work(struct work_struct *work);
619extern bool disable_work_sync(struct work_struct *work);
620extern bool enable_work(struct work_struct *work);
621
622extern bool disable_delayed_work(struct delayed_work *dwork);
623extern bool disable_delayed_work_sync(struct delayed_work *dwork);
624extern bool enable_delayed_work(struct delayed_work *dwork);
625
626extern bool flush_rcu_work(struct rcu_work *rwork);
627
628extern void workqueue_set_max_active(struct workqueue_struct *wq,
629 int max_active);
630extern void workqueue_set_min_active(struct workqueue_struct *wq,
631 int min_active);
632extern struct work_struct *current_work(void);
633extern bool current_is_workqueue_rescuer(void);
634extern bool workqueue_congested(int cpu, struct workqueue_struct *wq);
635extern unsigned int work_busy(struct work_struct *work);
636extern __printf(1, 2) void set_worker_desc(const char *fmt, ...);
637extern void print_worker_info(const char *log_lvl, struct task_struct *task);
638extern void show_all_workqueues(void);
639extern void show_freezable_workqueues(void);
640extern void show_one_workqueue(struct workqueue_struct *wq);
641extern void wq_worker_comm(char *buf, size_t size, struct task_struct *task);
642
643/**
644 * queue_work - queue work on a workqueue
645 * @wq: workqueue to use
646 * @work: work to queue
647 *
648 * Returns %false if @work was already on a queue, %true otherwise.
649 *
650 * We queue the work to the CPU on which it was submitted, but if the CPU dies
651 * it can be processed by another CPU.
652 *
653 * Memory-ordering properties: If it returns %true, guarantees that all stores
654 * preceding the call to queue_work() in the program order will be visible from
655 * the CPU which will execute @work by the time such work executes, e.g.,
656 *
657 * { x is initially 0 }
658 *
659 * CPU0 CPU1
660 *
661 * WRITE_ONCE(x, 1); [ @work is being executed ]
662 * r0 = queue_work(wq, work); r1 = READ_ONCE(x);
663 *
664 * Forbids: r0 == true && r1 == 0
665 */
666static inline bool queue_work(struct workqueue_struct *wq,
667 struct work_struct *work)
668{
669 return queue_work_on(cpu: WORK_CPU_UNBOUND, wq, work);
670}
671
672/**
673 * queue_delayed_work - queue work on a workqueue after delay
674 * @wq: workqueue to use
675 * @dwork: delayable work to queue
676 * @delay: number of jiffies to wait before queueing
677 *
678 * Equivalent to queue_delayed_work_on() but tries to use the local CPU.
679 */
680static inline bool queue_delayed_work(struct workqueue_struct *wq,
681 struct delayed_work *dwork,
682 unsigned long delay)
683{
684 return queue_delayed_work_on(cpu: WORK_CPU_UNBOUND, wq, work: dwork, delay);
685}
686
687/**
688 * mod_delayed_work - modify delay of or queue a delayed work
689 * @wq: workqueue to use
690 * @dwork: work to queue
691 * @delay: number of jiffies to wait before queueing
692 *
693 * mod_delayed_work_on() on local CPU.
694 */
695static inline bool mod_delayed_work(struct workqueue_struct *wq,
696 struct delayed_work *dwork,
697 unsigned long delay)
698{
699 return mod_delayed_work_on(cpu: WORK_CPU_UNBOUND, wq, dwork, delay);
700}
701
702/**
703 * schedule_work_on - put work task on a specific cpu
704 * @cpu: cpu to put the work task on
705 * @work: job to be done
706 *
707 * This puts a job on a specific cpu
708 */
709static inline bool schedule_work_on(int cpu, struct work_struct *work)
710{
711 return queue_work_on(cpu, wq: system_percpu_wq, work);
712}
713
714/**
715 * schedule_work - put work task in global workqueue
716 * @work: job to be done
717 *
718 * Returns %false if @work was already on the kernel-global workqueue and
719 * %true otherwise.
720 *
721 * This puts a job in the kernel-global workqueue if it was not already
722 * queued and leaves it in the same position on the kernel-global
723 * workqueue otherwise.
724 *
725 * Shares the same memory-ordering properties of queue_work(), cf. the
726 * DocBook header of queue_work().
727 */
728static inline bool schedule_work(struct work_struct *work)
729{
730 return queue_work(wq: system_percpu_wq, work);
731}
732
733/**
734 * enable_and_queue_work - Enable and queue a work item on a specific workqueue
735 * @wq: The target workqueue
736 * @work: The work item to be enabled and queued
737 *
738 * This function combines the operations of enable_work() and queue_work(),
739 * providing a convenient way to enable and queue a work item in a single call.
740 * It invokes enable_work() on @work and then queues it if the disable depth
741 * reached 0. Returns %true if the disable depth reached 0 and @work is queued,
742 * and %false otherwise.
743 *
744 * Note that @work is always queued when disable depth reaches zero. If the
745 * desired behavior is queueing only if certain events took place while @work is
746 * disabled, the user should implement the necessary state tracking and perform
747 * explicit conditional queueing after enable_work().
748 */
749static inline bool enable_and_queue_work(struct workqueue_struct *wq,
750 struct work_struct *work)
751{
752 if (enable_work(work)) {
753 queue_work(wq, work);
754 return true;
755 }
756 return false;
757}
758
759/*
760 * Detect attempt to flush system-wide workqueues at compile time when possible.
761 * Warn attempt to flush system-wide workqueues at runtime.
762 *
763 * See https://lkml.kernel.org/r/49925af7-78a8-a3dd-bce6-cfc02e1a9236@I-love.SAKURA.ne.jp
764 * for reasons and steps for converting system-wide workqueues into local workqueues.
765 */
766extern void __warn_flushing_systemwide_wq(void)
767 __compiletime_warning("Please avoid flushing system-wide workqueues.");
768
769/* Please stop using this function, for this function will be removed in near future. */
770#define flush_scheduled_work() \
771({ \
772 __warn_flushing_systemwide_wq(); \
773 __flush_workqueue(system_percpu_wq); \
774})
775
776#define flush_workqueue(wq) \
777({ \
778 struct workqueue_struct *_wq = (wq); \
779 \
780 if ((__builtin_constant_p(_wq == system_percpu_wq) && \
781 _wq == system_percpu_wq) || \
782 (__builtin_constant_p(_wq == system_highpri_wq) && \
783 _wq == system_highpri_wq) || \
784 (__builtin_constant_p(_wq == system_long_wq) && \
785 _wq == system_long_wq) || \
786 (__builtin_constant_p(_wq == system_dfl_wq) && \
787 _wq == system_dfl_wq) || \
788 (__builtin_constant_p(_wq == system_freezable_wq) && \
789 _wq == system_freezable_wq) || \
790 (__builtin_constant_p(_wq == system_power_efficient_wq) && \
791 _wq == system_power_efficient_wq) || \
792 (__builtin_constant_p(_wq == system_freezable_power_efficient_wq) && \
793 _wq == system_freezable_power_efficient_wq)) \
794 __warn_flushing_systemwide_wq(); \
795 __flush_workqueue(_wq); \
796})
797
798/**
799 * schedule_delayed_work_on - queue work in global workqueue on CPU after delay
800 * @cpu: cpu to use
801 * @dwork: job to be done
802 * @delay: number of jiffies to wait
803 *
804 * After waiting for a given time this puts a job in the kernel-global
805 * workqueue on the specified CPU.
806 */
807static inline bool schedule_delayed_work_on(int cpu, struct delayed_work *dwork,
808 unsigned long delay)
809{
810 return queue_delayed_work_on(cpu, wq: system_percpu_wq, work: dwork, delay);
811}
812
813/**
814 * schedule_delayed_work - put work task in global workqueue after delay
815 * @dwork: job to be done
816 * @delay: number of jiffies to wait or 0 for immediate execution
817 *
818 * After waiting for a given time this puts a job in the kernel-global
819 * workqueue.
820 */
821static inline bool schedule_delayed_work(struct delayed_work *dwork,
822 unsigned long delay)
823{
824 return queue_delayed_work(wq: system_percpu_wq, dwork, delay);
825}
826
827#ifndef CONFIG_SMP
828static inline long work_on_cpu(int cpu, long (*fn)(void *), void *arg)
829{
830 return fn(arg);
831}
832static inline long work_on_cpu_safe(int cpu, long (*fn)(void *), void *arg)
833{
834 return fn(arg);
835}
836#else
837long work_on_cpu_key(int cpu, long (*fn)(void *),
838 void *arg, struct lock_class_key *key);
839/*
840 * A new key is defined for each caller to make sure the work
841 * associated with the function doesn't share its locking class.
842 */
843#define work_on_cpu(_cpu, _fn, _arg) \
844({ \
845 static struct lock_class_key __key; \
846 \
847 work_on_cpu_key(_cpu, _fn, _arg, &__key); \
848})
849
850#endif /* CONFIG_SMP */
851
852#ifdef CONFIG_FREEZER
853extern void freeze_workqueues_begin(void);
854extern bool freeze_workqueues_busy(void);
855extern void thaw_workqueues(void);
856#endif /* CONFIG_FREEZER */
857
858#ifdef CONFIG_SYSFS
859int workqueue_sysfs_register(struct workqueue_struct *wq);
860#else /* CONFIG_SYSFS */
861static inline int workqueue_sysfs_register(struct workqueue_struct *wq)
862{ return 0; }
863#endif /* CONFIG_SYSFS */
864
865#ifdef CONFIG_WQ_WATCHDOG
866void wq_watchdog_touch(int cpu);
867#else /* CONFIG_WQ_WATCHDOG */
868static inline void wq_watchdog_touch(int cpu) { }
869#endif /* CONFIG_WQ_WATCHDOG */
870
871#ifdef CONFIG_SMP
872int workqueue_prepare_cpu(unsigned int cpu);
873int workqueue_online_cpu(unsigned int cpu);
874int workqueue_offline_cpu(unsigned int cpu);
875#endif
876
877void __init workqueue_init_early(void);
878void __init workqueue_init(void);
879void __init workqueue_init_topology(void);
880
881#endif
882

source code of linux/include/linux/workqueue.h