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_INACTIVE_BIT= 1,	/* work item is inactive */
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_INACTIVE	= 1 << WORK_STRUCT_INACTIVE_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 	WORK_NR_COLORS		= (1 << WORK_STRUCT_COLOR_BITS),
55 
56 	/* not bound to any CPU, prefer the local CPU */
57 	WORK_CPU_UNBOUND	= NR_CPUS,
58 
59 	/*
60 	 * Reserve 8 bits off of pwq pointer w/ debugobjects turned off.
61 	 * This makes pwqs aligned to 256 bytes and allows 16 workqueue
62 	 * flush colors.
63 	 */
64 	WORK_STRUCT_FLAG_BITS	= WORK_STRUCT_COLOR_SHIFT +
65 				  WORK_STRUCT_COLOR_BITS,
66 
67 	/* data contains off-queue information when !WORK_STRUCT_PWQ */
68 	WORK_OFFQ_FLAG_BASE	= WORK_STRUCT_COLOR_SHIFT,
69 
70 	__WORK_OFFQ_CANCELING	= WORK_OFFQ_FLAG_BASE,
71 
72 	/*
73 	 * When a work item is off queue, its high bits point to the last
74 	 * pool it was on.  Cap at 31 bits and use the highest number to
75 	 * indicate that no pool is associated.
76 	 */
77 	WORK_OFFQ_FLAG_BITS	= 1,
78 	WORK_OFFQ_POOL_SHIFT	= WORK_OFFQ_FLAG_BASE + WORK_OFFQ_FLAG_BITS,
79 	WORK_OFFQ_LEFT		= BITS_PER_LONG - WORK_OFFQ_POOL_SHIFT,
80 	WORK_OFFQ_POOL_BITS	= WORK_OFFQ_LEFT <= 31 ? WORK_OFFQ_LEFT : 31,
81 
82 	/* bit mask for work_busy() return values */
83 	WORK_BUSY_PENDING	= 1 << 0,
84 	WORK_BUSY_RUNNING	= 1 << 1,
85 
86 	/* maximum string length for set_worker_desc() */
87 	WORKER_DESC_LEN		= 24,
88 };
89 
90 /* Convenience constants - of type 'unsigned long', not 'enum'! */
91 #define WORK_OFFQ_CANCELING	(1ul << __WORK_OFFQ_CANCELING)
92 #define WORK_OFFQ_POOL_NONE	((1ul << WORK_OFFQ_POOL_BITS) - 1)
93 #define WORK_STRUCT_NO_POOL	(WORK_OFFQ_POOL_NONE << WORK_OFFQ_POOL_SHIFT)
94 
95 #define WORK_STRUCT_FLAG_MASK    ((1ul << WORK_STRUCT_FLAG_BITS) - 1)
96 #define WORK_STRUCT_WQ_DATA_MASK (~WORK_STRUCT_FLAG_MASK)
97 
98 struct work_struct {
99 	atomic_long_t data;
100 	struct list_head entry;
101 	work_func_t func;
102 #ifdef CONFIG_LOCKDEP
103 	struct lockdep_map lockdep_map;
104 #endif
105 };
106 
107 #define WORK_DATA_INIT()	ATOMIC_LONG_INIT((unsigned long)WORK_STRUCT_NO_POOL)
108 #define WORK_DATA_STATIC_INIT()	\
109 	ATOMIC_LONG_INIT((unsigned long)(WORK_STRUCT_NO_POOL | WORK_STRUCT_STATIC))
110 
111 struct delayed_work {
112 	struct work_struct work;
113 	struct timer_list timer;
114 
115 	/* target workqueue and CPU ->timer uses to queue ->work */
116 	struct workqueue_struct *wq;
117 	int cpu;
118 };
119 
120 struct rcu_work {
121 	struct work_struct work;
122 	struct rcu_head rcu;
123 
124 	/* target workqueue ->rcu uses to queue ->work */
125 	struct workqueue_struct *wq;
126 };
127 
128 enum wq_affn_scope {
129 	WQ_AFFN_DFL,			/* use system default */
130 	WQ_AFFN_CPU,			/* one pod per CPU */
131 	WQ_AFFN_SMT,			/* one pod poer SMT */
132 	WQ_AFFN_CACHE,			/* one pod per LLC */
133 	WQ_AFFN_NUMA,			/* one pod per NUMA node */
134 	WQ_AFFN_SYSTEM,			/* one pod across the whole system */
135 
136 	WQ_AFFN_NR_TYPES,
137 };
138 
139 /**
140  * struct workqueue_attrs - A struct for workqueue attributes.
141  *
142  * This can be used to change attributes of an unbound workqueue.
143  */
144 struct workqueue_attrs {
145 	/**
146 	 * @nice: nice level
147 	 */
148 	int nice;
149 
150 	/**
151 	 * @cpumask: allowed CPUs
152 	 *
153 	 * Work items in this workqueue are affine to these CPUs and not allowed
154 	 * to execute on other CPUs. A pool serving a workqueue must have the
155 	 * same @cpumask.
156 	 */
157 	cpumask_var_t cpumask;
158 
159 	/**
160 	 * @__pod_cpumask: internal attribute used to create per-pod pools
161 	 *
162 	 * Internal use only.
163 	 *
164 	 * Per-pod unbound worker pools are used to improve locality. Always a
165 	 * subset of ->cpumask. A workqueue can be associated with multiple
166 	 * worker pools with disjoint @__pod_cpumask's. Whether the enforcement
167 	 * of a pool's @__pod_cpumask is strict depends on @affn_strict.
168 	 */
169 	cpumask_var_t __pod_cpumask;
170 
171 	/**
172 	 * @affn_strict: affinity scope is strict
173 	 *
174 	 * If clear, workqueue will make a best-effort attempt at starting the
175 	 * worker inside @__pod_cpumask but the scheduler is free to migrate it
176 	 * outside.
177 	 *
178 	 * If set, workers are only allowed to run inside @__pod_cpumask.
179 	 */
180 	bool affn_strict;
181 
182 	/*
183 	 * Below fields aren't properties of a worker_pool. They only modify how
184 	 * :c:func:`apply_workqueue_attrs` select pools and thus don't
185 	 * participate in pool hash calculations or equality comparisons.
186 	 */
187 
188 	/**
189 	 * @affn_scope: unbound CPU affinity scope
190 	 *
191 	 * CPU pods are used to improve execution locality of unbound work
192 	 * items. There are multiple pod types, one for each wq_affn_scope, and
193 	 * every CPU in the system belongs to one pod in every pod type. CPUs
194 	 * that belong to the same pod share the worker pool. For example,
195 	 * selecting %WQ_AFFN_NUMA makes the workqueue use a separate worker
196 	 * pool for each NUMA node.
197 	 */
198 	enum wq_affn_scope affn_scope;
199 
200 	/**
201 	 * @ordered: work items must be executed one by one in queueing order
202 	 */
203 	bool ordered;
204 };
205 
to_delayed_work(struct work_struct * work)206 static inline struct delayed_work *to_delayed_work(struct work_struct *work)
207 {
208 	return container_of(work, struct delayed_work, work);
209 }
210 
to_rcu_work(struct work_struct * work)211 static inline struct rcu_work *to_rcu_work(struct work_struct *work)
212 {
213 	return container_of(work, struct rcu_work, work);
214 }
215 
216 struct execute_work {
217 	struct work_struct work;
218 };
219 
220 #ifdef CONFIG_LOCKDEP
221 /*
222  * NB: because we have to copy the lockdep_map, setting _key
223  * here is required, otherwise it could get initialised to the
224  * copy of the lockdep_map!
225  */
226 #define __WORK_INIT_LOCKDEP_MAP(n, k) \
227 	.lockdep_map = STATIC_LOCKDEP_MAP_INIT(n, k),
228 #else
229 #define __WORK_INIT_LOCKDEP_MAP(n, k)
230 #endif
231 
232 #define __WORK_INITIALIZER(n, f) {					\
233 	.data = WORK_DATA_STATIC_INIT(),				\
234 	.entry	= { &(n).entry, &(n).entry },				\
235 	.func = (f),							\
236 	__WORK_INIT_LOCKDEP_MAP(#n, &(n))				\
237 	}
238 
239 #define __DELAYED_WORK_INITIALIZER(n, f, tflags) {			\
240 	.work = __WORK_INITIALIZER((n).work, (f)),			\
241 	.timer = __TIMER_INITIALIZER(delayed_work_timer_fn,\
242 				     (tflags) | TIMER_IRQSAFE),		\
243 	}
244 
245 #define DECLARE_WORK(n, f)						\
246 	struct work_struct n = __WORK_INITIALIZER(n, f)
247 
248 #define DECLARE_DELAYED_WORK(n, f)					\
249 	struct delayed_work n = __DELAYED_WORK_INITIALIZER(n, f, 0)
250 
251 #define DECLARE_DEFERRABLE_WORK(n, f)					\
252 	struct delayed_work n = __DELAYED_WORK_INITIALIZER(n, f, TIMER_DEFERRABLE)
253 
254 #ifdef CONFIG_DEBUG_OBJECTS_WORK
255 extern void __init_work(struct work_struct *work, int onstack);
256 extern void destroy_work_on_stack(struct work_struct *work);
257 extern void destroy_delayed_work_on_stack(struct delayed_work *work);
work_static(struct work_struct * work)258 static inline unsigned int work_static(struct work_struct *work)
259 {
260 	return *work_data_bits(work) & WORK_STRUCT_STATIC;
261 }
262 #else
__init_work(struct work_struct * work,int onstack)263 static inline void __init_work(struct work_struct *work, int onstack) { }
destroy_work_on_stack(struct work_struct * work)264 static inline void destroy_work_on_stack(struct work_struct *work) { }
destroy_delayed_work_on_stack(struct delayed_work * work)265 static inline void destroy_delayed_work_on_stack(struct delayed_work *work) { }
work_static(struct work_struct * work)266 static inline unsigned int work_static(struct work_struct *work) { return 0; }
267 #endif
268 
269 /*
270  * initialize all of a work item in one go
271  *
272  * NOTE! No point in using "atomic_long_set()": using a direct
273  * assignment of the work data initializer allows the compiler
274  * to generate better code.
275  */
276 #ifdef CONFIG_LOCKDEP
277 #define __INIT_WORK_KEY(_work, _func, _onstack, _key)			\
278 	do {								\
279 		__init_work((_work), _onstack);				\
280 		(_work)->data = (atomic_long_t) WORK_DATA_INIT();	\
281 		lockdep_init_map(&(_work)->lockdep_map, "(work_completion)"#_work, (_key), 0); \
282 		INIT_LIST_HEAD(&(_work)->entry);			\
283 		(_work)->func = (_func);				\
284 	} while (0)
285 #else
286 #define __INIT_WORK_KEY(_work, _func, _onstack, _key)			\
287 	do {								\
288 		__init_work((_work), _onstack);				\
289 		(_work)->data = (atomic_long_t) WORK_DATA_INIT();	\
290 		INIT_LIST_HEAD(&(_work)->entry);			\
291 		(_work)->func = (_func);				\
292 	} while (0)
293 #endif
294 
295 #define __INIT_WORK(_work, _func, _onstack)				\
296 	do {								\
297 		static __maybe_unused struct lock_class_key __key;	\
298 									\
299 		__INIT_WORK_KEY(_work, _func, _onstack, &__key);	\
300 	} while (0)
301 
302 #define INIT_WORK(_work, _func)						\
303 	__INIT_WORK((_work), (_func), 0)
304 
305 #define INIT_WORK_ONSTACK(_work, _func)					\
306 	__INIT_WORK((_work), (_func), 1)
307 
308 #define INIT_WORK_ONSTACK_KEY(_work, _func, _key)			\
309 	__INIT_WORK_KEY((_work), (_func), 1, _key)
310 
311 #define __INIT_DELAYED_WORK(_work, _func, _tflags)			\
312 	do {								\
313 		INIT_WORK(&(_work)->work, (_func));			\
314 		__init_timer(&(_work)->timer,				\
315 			     delayed_work_timer_fn,			\
316 			     (_tflags) | TIMER_IRQSAFE);		\
317 	} while (0)
318 
319 #define __INIT_DELAYED_WORK_ONSTACK(_work, _func, _tflags)		\
320 	do {								\
321 		INIT_WORK_ONSTACK(&(_work)->work, (_func));		\
322 		__init_timer_on_stack(&(_work)->timer,			\
323 				      delayed_work_timer_fn,		\
324 				      (_tflags) | TIMER_IRQSAFE);	\
325 	} while (0)
326 
327 #define INIT_DELAYED_WORK(_work, _func)					\
328 	__INIT_DELAYED_WORK(_work, _func, 0)
329 
330 #define INIT_DELAYED_WORK_ONSTACK(_work, _func)				\
331 	__INIT_DELAYED_WORK_ONSTACK(_work, _func, 0)
332 
333 #define INIT_DEFERRABLE_WORK(_work, _func)				\
334 	__INIT_DELAYED_WORK(_work, _func, TIMER_DEFERRABLE)
335 
336 #define INIT_DEFERRABLE_WORK_ONSTACK(_work, _func)			\
337 	__INIT_DELAYED_WORK_ONSTACK(_work, _func, TIMER_DEFERRABLE)
338 
339 #define INIT_RCU_WORK(_work, _func)					\
340 	INIT_WORK(&(_work)->work, (_func))
341 
342 #define INIT_RCU_WORK_ONSTACK(_work, _func)				\
343 	INIT_WORK_ONSTACK(&(_work)->work, (_func))
344 
345 /**
346  * work_pending - Find out whether a work item is currently pending
347  * @work: The work item in question
348  */
349 #define work_pending(work) \
350 	test_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))
351 
352 /**
353  * delayed_work_pending - Find out whether a delayable work item is currently
354  * pending
355  * @w: The work item in question
356  */
357 #define delayed_work_pending(w) \
358 	work_pending(&(w)->work)
359 
360 /*
361  * Workqueue flags and constants.  For details, please refer to
362  * Documentation/core-api/workqueue.rst.
363  */
364 enum {
365 	WQ_UNBOUND		= 1 << 1, /* not bound to any cpu */
366 	WQ_FREEZABLE		= 1 << 2, /* freeze during suspend */
367 	WQ_MEM_RECLAIM		= 1 << 3, /* may be used for memory reclaim */
368 	WQ_HIGHPRI		= 1 << 4, /* high priority */
369 	WQ_CPU_INTENSIVE	= 1 << 5, /* cpu intensive workqueue */
370 	WQ_SYSFS		= 1 << 6, /* visible in sysfs, see workqueue_sysfs_register() */
371 
372 	/*
373 	 * Per-cpu workqueues are generally preferred because they tend to
374 	 * show better performance thanks to cache locality.  Per-cpu
375 	 * workqueues exclude the scheduler from choosing the CPU to
376 	 * execute the worker threads, which has an unfortunate side effect
377 	 * of increasing power consumption.
378 	 *
379 	 * The scheduler considers a CPU idle if it doesn't have any task
380 	 * to execute and tries to keep idle cores idle to conserve power;
381 	 * however, for example, a per-cpu work item scheduled from an
382 	 * interrupt handler on an idle CPU will force the scheduler to
383 	 * execute the work item on that CPU breaking the idleness, which in
384 	 * turn may lead to more scheduling choices which are sub-optimal
385 	 * in terms of power consumption.
386 	 *
387 	 * Workqueues marked with WQ_POWER_EFFICIENT are per-cpu by default
388 	 * but become unbound if workqueue.power_efficient kernel param is
389 	 * specified.  Per-cpu workqueues which are identified to
390 	 * contribute significantly to power-consumption are identified and
391 	 * marked with this flag and enabling the power_efficient mode
392 	 * leads to noticeable power saving at the cost of small
393 	 * performance disadvantage.
394 	 *
395 	 * http://thread.gmane.org/gmane.linux.kernel/1480396
396 	 */
397 	WQ_POWER_EFFICIENT	= 1 << 7,
398 
399 	__WQ_DESTROYING		= 1 << 15, /* internal: workqueue is destroying */
400 	__WQ_DRAINING		= 1 << 16, /* internal: workqueue is draining */
401 	__WQ_ORDERED		= 1 << 17, /* internal: workqueue is ordered */
402 	__WQ_LEGACY		= 1 << 18, /* internal: create*_workqueue() */
403 	__WQ_ORDERED_EXPLICIT	= 1 << 19, /* internal: alloc_ordered_workqueue() */
404 
405 	WQ_MAX_ACTIVE		= 512,	  /* I like 512, better ideas? */
406 	WQ_UNBOUND_MAX_ACTIVE	= WQ_MAX_ACTIVE,
407 	WQ_DFL_ACTIVE		= WQ_MAX_ACTIVE / 2,
408 };
409 
410 /*
411  * System-wide workqueues which are always present.
412  *
413  * system_wq is the one used by schedule[_delayed]_work[_on]().
414  * Multi-CPU multi-threaded.  There are users which expect relatively
415  * short queue flush time.  Don't queue works which can run for too
416  * long.
417  *
418  * system_highpri_wq is similar to system_wq but for work items which
419  * require WQ_HIGHPRI.
420  *
421  * system_long_wq is similar to system_wq but may host long running
422  * works.  Queue flushing might take relatively long.
423  *
424  * system_unbound_wq is unbound workqueue.  Workers are not bound to
425  * any specific CPU, not concurrency managed, and all queued works are
426  * executed immediately as long as max_active limit is not reached and
427  * resources are available.
428  *
429  * system_freezable_wq is equivalent to system_wq except that it's
430  * freezable.
431  *
432  * *_power_efficient_wq are inclined towards saving power and converted
433  * into WQ_UNBOUND variants if 'wq_power_efficient' is enabled; otherwise,
434  * they are same as their non-power-efficient counterparts - e.g.
435  * system_power_efficient_wq is identical to system_wq if
436  * 'wq_power_efficient' is disabled.  See WQ_POWER_EFFICIENT for more info.
437  */
438 extern struct workqueue_struct *system_wq;
439 extern struct workqueue_struct *system_highpri_wq;
440 extern struct workqueue_struct *system_long_wq;
441 extern struct workqueue_struct *system_unbound_wq;
442 extern struct workqueue_struct *system_freezable_wq;
443 extern struct workqueue_struct *system_power_efficient_wq;
444 extern struct workqueue_struct *system_freezable_power_efficient_wq;
445 
446 /**
447  * alloc_workqueue - allocate a workqueue
448  * @fmt: printf format for the name of the workqueue
449  * @flags: WQ_* flags
450  * @max_active: max in-flight work items per CPU, 0 for default
451  * remaining args: args for @fmt
452  *
453  * Allocate a workqueue with the specified parameters.  For detailed
454  * information on WQ_* flags, please refer to
455  * Documentation/core-api/workqueue.rst.
456  *
457  * RETURNS:
458  * Pointer to the allocated workqueue on success, %NULL on failure.
459  */
460 __printf(1, 4) struct workqueue_struct *
461 alloc_workqueue(const char *fmt, unsigned int flags, int max_active, ...);
462 
463 /**
464  * alloc_ordered_workqueue - allocate an ordered workqueue
465  * @fmt: printf format for the name of the workqueue
466  * @flags: WQ_* flags (only WQ_FREEZABLE and WQ_MEM_RECLAIM are meaningful)
467  * @args: args for @fmt
468  *
469  * Allocate an ordered workqueue.  An ordered workqueue executes at
470  * most one work item at any given time in the queued order.  They are
471  * implemented as unbound workqueues with @max_active of one.
472  *
473  * RETURNS:
474  * Pointer to the allocated workqueue on success, %NULL on failure.
475  */
476 #define alloc_ordered_workqueue(fmt, flags, args...)			\
477 	alloc_workqueue(fmt, WQ_UNBOUND | __WQ_ORDERED |		\
478 			__WQ_ORDERED_EXPLICIT | (flags), 1, ##args)
479 
480 #define create_workqueue(name)						\
481 	alloc_workqueue("%s", __WQ_LEGACY | WQ_MEM_RECLAIM, 1, (name))
482 #define create_freezable_workqueue(name)				\
483 	alloc_workqueue("%s", __WQ_LEGACY | WQ_FREEZABLE | WQ_UNBOUND |	\
484 			WQ_MEM_RECLAIM, 1, (name))
485 #define create_singlethread_workqueue(name)				\
486 	alloc_ordered_workqueue("%s", __WQ_LEGACY | WQ_MEM_RECLAIM, name)
487 
488 extern void destroy_workqueue(struct workqueue_struct *wq);
489 
490 struct workqueue_attrs *alloc_workqueue_attrs(void);
491 void free_workqueue_attrs(struct workqueue_attrs *attrs);
492 int apply_workqueue_attrs(struct workqueue_struct *wq,
493 			  const struct workqueue_attrs *attrs);
494 int workqueue_set_unbound_cpumask(cpumask_var_t cpumask);
495 
496 extern bool queue_work_on(int cpu, struct workqueue_struct *wq,
497 			struct work_struct *work);
498 extern bool queue_work_node(int node, struct workqueue_struct *wq,
499 			    struct work_struct *work);
500 extern bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
501 			struct delayed_work *work, unsigned long delay);
502 extern bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq,
503 			struct delayed_work *dwork, unsigned long delay);
504 extern bool queue_rcu_work(struct workqueue_struct *wq, struct rcu_work *rwork);
505 
506 extern void __flush_workqueue(struct workqueue_struct *wq);
507 extern void drain_workqueue(struct workqueue_struct *wq);
508 
509 extern int schedule_on_each_cpu(work_func_t func);
510 
511 int execute_in_process_context(work_func_t fn, struct execute_work *);
512 
513 extern bool flush_work(struct work_struct *work);
514 extern bool cancel_work(struct work_struct *work);
515 extern bool cancel_work_sync(struct work_struct *work);
516 
517 extern bool flush_delayed_work(struct delayed_work *dwork);
518 extern bool cancel_delayed_work(struct delayed_work *dwork);
519 extern bool cancel_delayed_work_sync(struct delayed_work *dwork);
520 
521 extern bool flush_rcu_work(struct rcu_work *rwork);
522 
523 extern void workqueue_set_max_active(struct workqueue_struct *wq,
524 				     int max_active);
525 extern struct work_struct *current_work(void);
526 extern bool current_is_workqueue_rescuer(void);
527 extern bool workqueue_congested(int cpu, struct workqueue_struct *wq);
528 extern unsigned int work_busy(struct work_struct *work);
529 extern __printf(1, 2) void set_worker_desc(const char *fmt, ...);
530 extern void print_worker_info(const char *log_lvl, struct task_struct *task);
531 extern void show_all_workqueues(void);
532 extern void show_freezable_workqueues(void);
533 extern void show_one_workqueue(struct workqueue_struct *wq);
534 extern void wq_worker_comm(char *buf, size_t size, struct task_struct *task);
535 
536 /**
537  * queue_work - queue work on a workqueue
538  * @wq: workqueue to use
539  * @work: work to queue
540  *
541  * Returns %false if @work was already on a queue, %true otherwise.
542  *
543  * We queue the work to the CPU on which it was submitted, but if the CPU dies
544  * it can be processed by another CPU.
545  *
546  * Memory-ordering properties:  If it returns %true, guarantees that all stores
547  * preceding the call to queue_work() in the program order will be visible from
548  * the CPU which will execute @work by the time such work executes, e.g.,
549  *
550  * { x is initially 0 }
551  *
552  *   CPU0				CPU1
553  *
554  *   WRITE_ONCE(x, 1);			[ @work is being executed ]
555  *   r0 = queue_work(wq, work);		  r1 = READ_ONCE(x);
556  *
557  * Forbids: r0 == true && r1 == 0
558  */
queue_work(struct workqueue_struct * wq,struct work_struct * work)559 static inline bool queue_work(struct workqueue_struct *wq,
560 			      struct work_struct *work)
561 {
562 	return queue_work_on(WORK_CPU_UNBOUND, wq, work);
563 }
564 
565 /**
566  * queue_delayed_work - queue work on a workqueue after delay
567  * @wq: workqueue to use
568  * @dwork: delayable work to queue
569  * @delay: number of jiffies to wait before queueing
570  *
571  * Equivalent to queue_delayed_work_on() but tries to use the local CPU.
572  */
queue_delayed_work(struct workqueue_struct * wq,struct delayed_work * dwork,unsigned long delay)573 static inline bool queue_delayed_work(struct workqueue_struct *wq,
574 				      struct delayed_work *dwork,
575 				      unsigned long delay)
576 {
577 	return queue_delayed_work_on(WORK_CPU_UNBOUND, wq, dwork, delay);
578 }
579 
580 /**
581  * mod_delayed_work - modify delay of or queue a delayed work
582  * @wq: workqueue to use
583  * @dwork: work to queue
584  * @delay: number of jiffies to wait before queueing
585  *
586  * mod_delayed_work_on() on local CPU.
587  */
mod_delayed_work(struct workqueue_struct * wq,struct delayed_work * dwork,unsigned long delay)588 static inline bool mod_delayed_work(struct workqueue_struct *wq,
589 				    struct delayed_work *dwork,
590 				    unsigned long delay)
591 {
592 	return mod_delayed_work_on(WORK_CPU_UNBOUND, wq, dwork, delay);
593 }
594 
595 /**
596  * schedule_work_on - put work task on a specific cpu
597  * @cpu: cpu to put the work task on
598  * @work: job to be done
599  *
600  * This puts a job on a specific cpu
601  */
schedule_work_on(int cpu,struct work_struct * work)602 static inline bool schedule_work_on(int cpu, struct work_struct *work)
603 {
604 	return queue_work_on(cpu, system_wq, work);
605 }
606 
607 /**
608  * schedule_work - put work task in global workqueue
609  * @work: job to be done
610  *
611  * Returns %false if @work was already on the kernel-global workqueue and
612  * %true otherwise.
613  *
614  * This puts a job in the kernel-global workqueue if it was not already
615  * queued and leaves it in the same position on the kernel-global
616  * workqueue otherwise.
617  *
618  * Shares the same memory-ordering properties of queue_work(), cf. the
619  * DocBook header of queue_work().
620  */
schedule_work(struct work_struct * work)621 static inline bool schedule_work(struct work_struct *work)
622 {
623 	return queue_work(system_wq, work);
624 }
625 
626 /*
627  * Detect attempt to flush system-wide workqueues at compile time when possible.
628  * Warn attempt to flush system-wide workqueues at runtime.
629  *
630  * See https://lkml.kernel.org/r/49925af7-78a8-a3dd-bce6-cfc02e1a9236@I-love.SAKURA.ne.jp
631  * for reasons and steps for converting system-wide workqueues into local workqueues.
632  */
633 extern void __warn_flushing_systemwide_wq(void)
634 	__compiletime_warning("Please avoid flushing system-wide workqueues.");
635 
636 /* Please stop using this function, for this function will be removed in near future. */
637 #define flush_scheduled_work()						\
638 ({									\
639 	__warn_flushing_systemwide_wq();				\
640 	__flush_workqueue(system_wq);					\
641 })
642 
643 #define flush_workqueue(wq)						\
644 ({									\
645 	struct workqueue_struct *_wq = (wq);				\
646 									\
647 	if ((__builtin_constant_p(_wq == system_wq) &&			\
648 	     _wq == system_wq) ||					\
649 	    (__builtin_constant_p(_wq == system_highpri_wq) &&		\
650 	     _wq == system_highpri_wq) ||				\
651 	    (__builtin_constant_p(_wq == system_long_wq) &&		\
652 	     _wq == system_long_wq) ||					\
653 	    (__builtin_constant_p(_wq == system_unbound_wq) &&		\
654 	     _wq == system_unbound_wq) ||				\
655 	    (__builtin_constant_p(_wq == system_freezable_wq) &&	\
656 	     _wq == system_freezable_wq) ||				\
657 	    (__builtin_constant_p(_wq == system_power_efficient_wq) &&	\
658 	     _wq == system_power_efficient_wq) ||			\
659 	    (__builtin_constant_p(_wq == system_freezable_power_efficient_wq) && \
660 	     _wq == system_freezable_power_efficient_wq))		\
661 		__warn_flushing_systemwide_wq();			\
662 	__flush_workqueue(_wq);						\
663 })
664 
665 /**
666  * schedule_delayed_work_on - queue work in global workqueue on CPU after delay
667  * @cpu: cpu to use
668  * @dwork: job to be done
669  * @delay: number of jiffies to wait
670  *
671  * After waiting for a given time this puts a job in the kernel-global
672  * workqueue on the specified CPU.
673  */
schedule_delayed_work_on(int cpu,struct delayed_work * dwork,unsigned long delay)674 static inline bool schedule_delayed_work_on(int cpu, struct delayed_work *dwork,
675 					    unsigned long delay)
676 {
677 	return queue_delayed_work_on(cpu, system_wq, dwork, delay);
678 }
679 
680 /**
681  * schedule_delayed_work - put work task in global workqueue after delay
682  * @dwork: job to be done
683  * @delay: number of jiffies to wait or 0 for immediate execution
684  *
685  * After waiting for a given time this puts a job in the kernel-global
686  * workqueue.
687  */
schedule_delayed_work(struct delayed_work * dwork,unsigned long delay)688 static inline bool schedule_delayed_work(struct delayed_work *dwork,
689 					 unsigned long delay)
690 {
691 	return queue_delayed_work(system_wq, dwork, delay);
692 }
693 
694 #ifndef CONFIG_SMP
work_on_cpu(int cpu,long (* fn)(void *),void * arg)695 static inline long work_on_cpu(int cpu, long (*fn)(void *), void *arg)
696 {
697 	return fn(arg);
698 }
work_on_cpu_safe(int cpu,long (* fn)(void *),void * arg)699 static inline long work_on_cpu_safe(int cpu, long (*fn)(void *), void *arg)
700 {
701 	return fn(arg);
702 }
703 #else
704 long work_on_cpu_key(int cpu, long (*fn)(void *),
705 		     void *arg, struct lock_class_key *key);
706 /*
707  * A new key is defined for each caller to make sure the work
708  * associated with the function doesn't share its locking class.
709  */
710 #define work_on_cpu(_cpu, _fn, _arg)			\
711 ({							\
712 	static struct lock_class_key __key;		\
713 							\
714 	work_on_cpu_key(_cpu, _fn, _arg, &__key);	\
715 })
716 
717 long work_on_cpu_safe_key(int cpu, long (*fn)(void *),
718 			  void *arg, struct lock_class_key *key);
719 
720 /*
721  * A new key is defined for each caller to make sure the work
722  * associated with the function doesn't share its locking class.
723  */
724 #define work_on_cpu_safe(_cpu, _fn, _arg)		\
725 ({							\
726 	static struct lock_class_key __key;		\
727 							\
728 	work_on_cpu_safe_key(_cpu, _fn, _arg, &__key);	\
729 })
730 #endif /* CONFIG_SMP */
731 
732 #ifdef CONFIG_FREEZER
733 extern void freeze_workqueues_begin(void);
734 extern bool freeze_workqueues_busy(void);
735 extern void thaw_workqueues(void);
736 #endif /* CONFIG_FREEZER */
737 
738 #ifdef CONFIG_SYSFS
739 int workqueue_sysfs_register(struct workqueue_struct *wq);
740 #else	/* CONFIG_SYSFS */
workqueue_sysfs_register(struct workqueue_struct * wq)741 static inline int workqueue_sysfs_register(struct workqueue_struct *wq)
742 { return 0; }
743 #endif	/* CONFIG_SYSFS */
744 
745 #ifdef CONFIG_WQ_WATCHDOG
746 void wq_watchdog_touch(int cpu);
747 #else	/* CONFIG_WQ_WATCHDOG */
wq_watchdog_touch(int cpu)748 static inline void wq_watchdog_touch(int cpu) { }
749 #endif	/* CONFIG_WQ_WATCHDOG */
750 
751 #ifdef CONFIG_SMP
752 int workqueue_prepare_cpu(unsigned int cpu);
753 int workqueue_online_cpu(unsigned int cpu);
754 int workqueue_offline_cpu(unsigned int cpu);
755 #endif
756 
757 void __init workqueue_init_early(void);
758 void __init workqueue_init(void);
759 void __init workqueue_init_topology(void);
760 
761 #endif
762