2 * workqueue.h --- work queue handling for Linux.
5 #ifndef _LINUX_WORKQUEUE_H
6 #define _LINUX_WORKQUEUE_H
8 #include <linux/timer.h>
9 #include <linux/linkage.h>
10 #include <linux/bitops.h>
11 #include <linux/lockdep.h>
12 #include <linux/threads.h>
13 #include <linux/atomic.h>
14 #include <linux/cpumask.h>
16 struct workqueue_struct;
19 typedef void (*work_func_t)(struct work_struct *work);
20 void delayed_work_timer_fn(unsigned long __data);
23 * The first word is the work queue pointer and the flags rolled into
26 #define work_data_bits(work) ((unsigned long *)(&(work)->data))
29 WORK_STRUCT_PENDING_BIT = 0, /* work item is pending execution */
30 WORK_STRUCT_DELAYED_BIT = 1, /* work item is delayed */
31 WORK_STRUCT_PWQ_BIT = 2, /* data points to pwq */
32 WORK_STRUCT_LINKED_BIT = 3, /* next work is linked to this one */
33 #ifdef CONFIG_DEBUG_OBJECTS_WORK
34 WORK_STRUCT_STATIC_BIT = 4, /* static initializer (debugobjects) */
35 WORK_STRUCT_COLOR_SHIFT = 5, /* color for workqueue flushing */
37 WORK_STRUCT_COLOR_SHIFT = 4, /* color for workqueue flushing */
40 WORK_STRUCT_COLOR_BITS = 4,
42 WORK_STRUCT_PENDING = 1 << WORK_STRUCT_PENDING_BIT,
43 WORK_STRUCT_DELAYED = 1 << WORK_STRUCT_DELAYED_BIT,
44 WORK_STRUCT_PWQ = 1 << WORK_STRUCT_PWQ_BIT,
45 WORK_STRUCT_LINKED = 1 << WORK_STRUCT_LINKED_BIT,
46 #ifdef CONFIG_DEBUG_OBJECTS_WORK
47 WORK_STRUCT_STATIC = 1 << WORK_STRUCT_STATIC_BIT,
49 WORK_STRUCT_STATIC = 0,
53 * The last color is no color used for works which don't
54 * participate in workqueue flushing.
56 WORK_NR_COLORS = (1 << WORK_STRUCT_COLOR_BITS) - 1,
57 WORK_NO_COLOR = WORK_NR_COLORS,
59 /* not bound to any CPU, prefer the local CPU */
60 WORK_CPU_UNBOUND = NR_CPUS,
63 * Reserve 7 bits off of pwq pointer w/ debugobjects turned off.
64 * This makes pwqs aligned to 256 bytes and allows 15 workqueue
67 WORK_STRUCT_FLAG_BITS = WORK_STRUCT_COLOR_SHIFT +
68 WORK_STRUCT_COLOR_BITS,
70 /* data contains off-queue information when !WORK_STRUCT_PWQ */
71 WORK_OFFQ_FLAG_BASE = WORK_STRUCT_COLOR_SHIFT,
73 __WORK_OFFQ_CANCELING = WORK_OFFQ_FLAG_BASE,
74 WORK_OFFQ_CANCELING = (1 << __WORK_OFFQ_CANCELING),
77 * When a work item is off queue, its high bits point to the last
78 * pool it was on. Cap at 31 bits and use the highest number to
79 * indicate that no pool is associated.
81 WORK_OFFQ_FLAG_BITS = 1,
82 WORK_OFFQ_POOL_SHIFT = WORK_OFFQ_FLAG_BASE + WORK_OFFQ_FLAG_BITS,
83 WORK_OFFQ_LEFT = BITS_PER_LONG - WORK_OFFQ_POOL_SHIFT,
84 WORK_OFFQ_POOL_BITS = WORK_OFFQ_LEFT <= 31 ? WORK_OFFQ_LEFT : 31,
85 WORK_OFFQ_POOL_NONE = (1LU << WORK_OFFQ_POOL_BITS) - 1,
87 /* convenience constants */
88 WORK_STRUCT_FLAG_MASK = (1UL << WORK_STRUCT_FLAG_BITS) - 1,
89 WORK_STRUCT_WQ_DATA_MASK = ~WORK_STRUCT_FLAG_MASK,
90 WORK_STRUCT_NO_POOL = (unsigned long)WORK_OFFQ_POOL_NONE << WORK_OFFQ_POOL_SHIFT,
92 /* bit mask for work_busy() return values */
93 WORK_BUSY_PENDING = 1 << 0,
94 WORK_BUSY_RUNNING = 1 << 1,
96 /* maximum string length for set_worker_desc() */
102 struct list_head entry;
104 #ifdef CONFIG_LOCKDEP
105 struct lockdep_map lockdep_map;
109 #define WORK_DATA_INIT() ATOMIC_LONG_INIT(WORK_STRUCT_NO_POOL)
110 #define WORK_DATA_STATIC_INIT() \
111 ATOMIC_LONG_INIT(WORK_STRUCT_NO_POOL | WORK_STRUCT_STATIC)
113 struct delayed_work {
114 struct work_struct work;
115 struct timer_list timer;
117 /* target workqueue and CPU ->timer uses to queue ->work */
118 struct workqueue_struct *wq;
123 * A struct for workqueue attributes. This can be used to change
124 * attributes of an unbound workqueue.
126 * Unlike other fields, ->no_numa isn't a property of a worker_pool. It
127 * only modifies how apply_workqueue_attrs() select pools and thus doesn't
128 * participate in pool hash calculations or equality comparisons.
130 struct workqueue_attrs {
131 int nice; /* nice level */
132 cpumask_var_t cpumask; /* allowed CPUs */
133 bool no_numa; /* disable NUMA affinity */
136 static inline struct delayed_work *to_delayed_work(struct work_struct *work)
138 return container_of(work, struct delayed_work, work);
141 struct execute_work {
142 struct work_struct work;
145 #ifdef CONFIG_LOCKDEP
147 * NB: because we have to copy the lockdep_map, setting _key
148 * here is required, otherwise it could get initialised to the
149 * copy of the lockdep_map!
151 #define __WORK_INIT_LOCKDEP_MAP(n, k) \
152 .lockdep_map = STATIC_LOCKDEP_MAP_INIT(n, k),
154 #define __WORK_INIT_LOCKDEP_MAP(n, k)
157 #define __WORK_INITIALIZER(n, f) { \
158 .data = WORK_DATA_STATIC_INIT(), \
159 .entry = { &(n).entry, &(n).entry }, \
161 __WORK_INIT_LOCKDEP_MAP(#n, &(n)) \
164 #define __DELAYED_WORK_INITIALIZER(n, f, tflags) { \
165 .work = __WORK_INITIALIZER((n).work, (f)), \
166 .timer = __TIMER_INITIALIZER(delayed_work_timer_fn, \
167 0, (unsigned long)&(n), \
168 (tflags) | TIMER_IRQSAFE), \
171 #define DECLARE_WORK(n, f) \
172 struct work_struct n = __WORK_INITIALIZER(n, f)
174 #define DECLARE_DELAYED_WORK(n, f) \
175 struct delayed_work n = __DELAYED_WORK_INITIALIZER(n, f, 0)
177 #define DECLARE_DEFERRABLE_WORK(n, f) \
178 struct delayed_work n = __DELAYED_WORK_INITIALIZER(n, f, TIMER_DEFERRABLE)
180 #ifdef CONFIG_DEBUG_OBJECTS_WORK
181 extern void __init_work(struct work_struct *work, int onstack);
182 extern void destroy_work_on_stack(struct work_struct *work);
183 extern void destroy_delayed_work_on_stack(struct delayed_work *work);
184 static inline unsigned int work_static(struct work_struct *work)
186 return *work_data_bits(work) & WORK_STRUCT_STATIC;
189 static inline void __init_work(struct work_struct *work, int onstack) { }
190 static inline void destroy_work_on_stack(struct work_struct *work) { }
191 static inline void destroy_delayed_work_on_stack(struct delayed_work *work) { }
192 static inline unsigned int work_static(struct work_struct *work) { return 0; }
196 * initialize all of a work item in one go
198 * NOTE! No point in using "atomic_long_set()": using a direct
199 * assignment of the work data initializer allows the compiler
200 * to generate better code.
202 #ifdef CONFIG_LOCKDEP
203 #define __INIT_WORK(_work, _func, _onstack) \
205 static struct lock_class_key __key; \
207 __init_work((_work), _onstack); \
208 (_work)->data = (atomic_long_t) WORK_DATA_INIT(); \
209 lockdep_init_map(&(_work)->lockdep_map, #_work, &__key, 0); \
210 INIT_LIST_HEAD(&(_work)->entry); \
211 (_work)->func = (_func); \
214 #define __INIT_WORK(_work, _func, _onstack) \
216 __init_work((_work), _onstack); \
217 (_work)->data = (atomic_long_t) WORK_DATA_INIT(); \
218 INIT_LIST_HEAD(&(_work)->entry); \
219 (_work)->func = (_func); \
223 #define INIT_WORK(_work, _func) \
224 __INIT_WORK((_work), (_func), 0)
226 #define INIT_WORK_ONSTACK(_work, _func) \
227 __INIT_WORK((_work), (_func), 1)
229 #define __INIT_DELAYED_WORK(_work, _func, _tflags) \
231 INIT_WORK(&(_work)->work, (_func)); \
232 __setup_timer(&(_work)->timer, delayed_work_timer_fn, \
233 (unsigned long)(_work), \
234 (_tflags) | TIMER_IRQSAFE); \
237 #define __INIT_DELAYED_WORK_ONSTACK(_work, _func, _tflags) \
239 INIT_WORK_ONSTACK(&(_work)->work, (_func)); \
240 __setup_timer_on_stack(&(_work)->timer, \
241 delayed_work_timer_fn, \
242 (unsigned long)(_work), \
243 (_tflags) | TIMER_IRQSAFE); \
246 #define INIT_DELAYED_WORK(_work, _func) \
247 __INIT_DELAYED_WORK(_work, _func, 0)
249 #define INIT_DELAYED_WORK_ONSTACK(_work, _func) \
250 __INIT_DELAYED_WORK_ONSTACK(_work, _func, 0)
252 #define INIT_DEFERRABLE_WORK(_work, _func) \
253 __INIT_DELAYED_WORK(_work, _func, TIMER_DEFERRABLE)
255 #define INIT_DEFERRABLE_WORK_ONSTACK(_work, _func) \
256 __INIT_DELAYED_WORK_ONSTACK(_work, _func, TIMER_DEFERRABLE)
259 * work_pending - Find out whether a work item is currently pending
260 * @work: The work item in question
262 #define work_pending(work) \
263 test_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))
266 * delayed_work_pending - Find out whether a delayable work item is currently
268 * @w: The work item in question
270 #define delayed_work_pending(w) \
271 work_pending(&(w)->work)
274 * Workqueue flags and constants. For details, please refer to
275 * Documentation/workqueue.txt.
278 WQ_UNBOUND = 1 << 1, /* not bound to any cpu */
279 WQ_FREEZABLE = 1 << 2, /* freeze during suspend */
280 WQ_MEM_RECLAIM = 1 << 3, /* may be used for memory reclaim */
281 WQ_HIGHPRI = 1 << 4, /* high priority */
282 WQ_CPU_INTENSIVE = 1 << 5, /* cpu intensive workqueue */
283 WQ_SYSFS = 1 << 6, /* visible in sysfs, see wq_sysfs_register() */
286 * Per-cpu workqueues are generally preferred because they tend to
287 * show better performance thanks to cache locality. Per-cpu
288 * workqueues exclude the scheduler from choosing the CPU to
289 * execute the worker threads, which has an unfortunate side effect
290 * of increasing power consumption.
292 * The scheduler considers a CPU idle if it doesn't have any task
293 * to execute and tries to keep idle cores idle to conserve power;
294 * however, for example, a per-cpu work item scheduled from an
295 * interrupt handler on an idle CPU will force the scheduler to
296 * excute the work item on that CPU breaking the idleness, which in
297 * turn may lead to more scheduling choices which are sub-optimal
298 * in terms of power consumption.
300 * Workqueues marked with WQ_POWER_EFFICIENT are per-cpu by default
301 * but become unbound if workqueue.power_efficient kernel param is
302 * specified. Per-cpu workqueues which are identified to
303 * contribute significantly to power-consumption are identified and
304 * marked with this flag and enabling the power_efficient mode
305 * leads to noticeable power saving at the cost of small
306 * performance disadvantage.
308 * http://thread.gmane.org/gmane.linux.kernel/1480396
310 WQ_POWER_EFFICIENT = 1 << 7,
312 __WQ_DRAINING = 1 << 16, /* internal: workqueue is draining */
313 __WQ_ORDERED = 1 << 17, /* internal: workqueue is ordered */
315 WQ_MAX_ACTIVE = 512, /* I like 512, better ideas? */
316 WQ_MAX_UNBOUND_PER_CPU = 4, /* 4 * #cpus for unbound wq */
317 WQ_DFL_ACTIVE = WQ_MAX_ACTIVE / 2,
320 /* unbound wq's aren't per-cpu, scale max_active according to #cpus */
321 #define WQ_UNBOUND_MAX_ACTIVE \
322 max_t(int, WQ_MAX_ACTIVE, num_possible_cpus() * WQ_MAX_UNBOUND_PER_CPU)
325 * System-wide workqueues which are always present.
327 * system_wq is the one used by schedule[_delayed]_work[_on]().
328 * Multi-CPU multi-threaded. There are users which expect relatively
329 * short queue flush time. Don't queue works which can run for too
332 * system_highpri_wq is similar to system_wq but for work items which
333 * require WQ_HIGHPRI.
335 * system_long_wq is similar to system_wq but may host long running
336 * works. Queue flushing might take relatively long.
338 * system_unbound_wq is unbound workqueue. Workers are not bound to
339 * any specific CPU, not concurrency managed, and all queued works are
340 * executed immediately as long as max_active limit is not reached and
341 * resources are available.
343 * system_freezable_wq is equivalent to system_wq except that it's
346 * *_power_efficient_wq are inclined towards saving power and converted
347 * into WQ_UNBOUND variants if 'wq_power_efficient' is enabled; otherwise,
348 * they are same as their non-power-efficient counterparts - e.g.
349 * system_power_efficient_wq is identical to system_wq if
350 * 'wq_power_efficient' is disabled. See WQ_POWER_EFFICIENT for more info.
352 extern struct workqueue_struct *system_wq;
353 extern struct workqueue_struct *system_highpri_wq;
354 extern struct workqueue_struct *system_long_wq;
355 extern struct workqueue_struct *system_unbound_wq;
356 extern struct workqueue_struct *system_freezable_wq;
357 extern struct workqueue_struct *system_power_efficient_wq;
358 extern struct workqueue_struct *system_freezable_power_efficient_wq;
360 extern struct workqueue_struct *
361 __alloc_workqueue_key(const char *fmt, unsigned int flags, int max_active,
362 struct lock_class_key *key, const char *lock_name, ...) __printf(1, 6);
365 * alloc_workqueue - allocate a workqueue
366 * @fmt: printf format for the name of the workqueue
368 * @max_active: max in-flight work items, 0 for default
369 * @args...: args for @fmt
371 * Allocate a workqueue with the specified parameters. For detailed
372 * information on WQ_* flags, please refer to Documentation/workqueue.txt.
374 * The __lock_name macro dance is to guarantee that single lock_class_key
375 * doesn't end up with different namesm, which isn't allowed by lockdep.
378 * Pointer to the allocated workqueue on success, %NULL on failure.
380 #ifdef CONFIG_LOCKDEP
381 #define alloc_workqueue(fmt, flags, max_active, args...) \
383 static struct lock_class_key __key; \
384 const char *__lock_name; \
386 __lock_name = #fmt#args; \
388 __alloc_workqueue_key((fmt), (flags), (max_active), \
389 &__key, __lock_name, ##args); \
392 #define alloc_workqueue(fmt, flags, max_active, args...) \
393 __alloc_workqueue_key((fmt), (flags), (max_active), \
398 * alloc_ordered_workqueue - allocate an ordered workqueue
399 * @fmt: printf format for the name of the workqueue
400 * @flags: WQ_* flags (only WQ_FREEZABLE and WQ_MEM_RECLAIM are meaningful)
401 * @args...: args for @fmt
403 * Allocate an ordered workqueue. An ordered workqueue executes at
404 * most one work item at any given time in the queued order. They are
405 * implemented as unbound workqueues with @max_active of one.
408 * Pointer to the allocated workqueue on success, %NULL on failure.
410 #define alloc_ordered_workqueue(fmt, flags, args...) \
411 alloc_workqueue(fmt, WQ_UNBOUND | __WQ_ORDERED | (flags), 1, ##args)
413 #define create_workqueue(name) \
414 alloc_workqueue("%s", WQ_MEM_RECLAIM, 1, (name))
415 #define create_freezable_workqueue(name) \
416 alloc_workqueue("%s", WQ_FREEZABLE | WQ_UNBOUND | WQ_MEM_RECLAIM, \
418 #define create_singlethread_workqueue(name) \
419 alloc_ordered_workqueue("%s", WQ_MEM_RECLAIM, name)
421 extern void destroy_workqueue(struct workqueue_struct *wq);
423 struct workqueue_attrs *alloc_workqueue_attrs(gfp_t gfp_mask);
424 void free_workqueue_attrs(struct workqueue_attrs *attrs);
425 int apply_workqueue_attrs(struct workqueue_struct *wq,
426 const struct workqueue_attrs *attrs);
427 int workqueue_set_unbound_cpumask(cpumask_var_t cpumask);
429 extern bool queue_work_on(int cpu, struct workqueue_struct *wq,
430 struct work_struct *work);
431 extern bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
432 struct delayed_work *work, unsigned long delay);
433 extern bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq,
434 struct delayed_work *dwork, unsigned long delay);
436 extern void flush_workqueue(struct workqueue_struct *wq);
437 extern void drain_workqueue(struct workqueue_struct *wq);
439 extern int schedule_on_each_cpu(work_func_t func);
441 int execute_in_process_context(work_func_t fn, struct execute_work *);
443 extern bool flush_work(struct work_struct *work);
444 extern bool cancel_work_sync(struct work_struct *work);
446 extern bool flush_delayed_work(struct delayed_work *dwork);
447 extern bool cancel_delayed_work(struct delayed_work *dwork);
448 extern bool cancel_delayed_work_sync(struct delayed_work *dwork);
450 extern void workqueue_set_max_active(struct workqueue_struct *wq,
452 extern bool current_is_workqueue_rescuer(void);
453 extern bool workqueue_congested(int cpu, struct workqueue_struct *wq);
454 extern unsigned int work_busy(struct work_struct *work);
455 extern __printf(1, 2) void set_worker_desc(const char *fmt, ...);
456 extern void print_worker_info(const char *log_lvl, struct task_struct *task);
457 extern void show_workqueue_state(void);
460 * queue_work - queue work on a workqueue
461 * @wq: workqueue to use
462 * @work: work to queue
464 * Returns %false if @work was already on a queue, %true otherwise.
466 * We queue the work to the CPU on which it was submitted, but if the CPU dies
467 * it can be processed by another CPU.
469 static inline bool queue_work(struct workqueue_struct *wq,
470 struct work_struct *work)
472 return queue_work_on(WORK_CPU_UNBOUND, wq, work);
476 * queue_delayed_work - queue work on a workqueue after delay
477 * @wq: workqueue to use
478 * @dwork: delayable work to queue
479 * @delay: number of jiffies to wait before queueing
481 * Equivalent to queue_delayed_work_on() but tries to use the local CPU.
483 static inline bool queue_delayed_work(struct workqueue_struct *wq,
484 struct delayed_work *dwork,
487 return queue_delayed_work_on(WORK_CPU_UNBOUND, wq, dwork, delay);
491 * mod_delayed_work - modify delay of or queue a delayed work
492 * @wq: workqueue to use
493 * @dwork: work to queue
494 * @delay: number of jiffies to wait before queueing
496 * mod_delayed_work_on() on local CPU.
498 static inline bool mod_delayed_work(struct workqueue_struct *wq,
499 struct delayed_work *dwork,
502 return mod_delayed_work_on(WORK_CPU_UNBOUND, wq, dwork, delay);
506 * schedule_work_on - put work task on a specific cpu
507 * @cpu: cpu to put the work task on
508 * @work: job to be done
510 * This puts a job on a specific cpu
512 static inline bool schedule_work_on(int cpu, struct work_struct *work)
514 return queue_work_on(cpu, system_wq, work);
518 * schedule_work - put work task in global workqueue
519 * @work: job to be done
521 * Returns %false if @work was already on the kernel-global workqueue and
524 * This puts a job in the kernel-global workqueue if it was not already
525 * queued and leaves it in the same position on the kernel-global
526 * workqueue otherwise.
528 static inline bool schedule_work(struct work_struct *work)
530 return queue_work(system_wq, work);
534 * flush_scheduled_work - ensure that any scheduled work has run to completion.
536 * Forces execution of the kernel-global workqueue and blocks until its
539 * Think twice before calling this function! It's very easy to get into
540 * trouble if you don't take great care. Either of the following situations
541 * will lead to deadlock:
543 * One of the work items currently on the workqueue needs to acquire
544 * a lock held by your code or its caller.
546 * Your code is running in the context of a work routine.
548 * They will be detected by lockdep when they occur, but the first might not
549 * occur very often. It depends on what work items are on the workqueue and
550 * what locks they need, which you have no control over.
552 * In most situations flushing the entire workqueue is overkill; you merely
553 * need to know that a particular work item isn't queued and isn't running.
554 * In such cases you should use cancel_delayed_work_sync() or
555 * cancel_work_sync() instead.
557 static inline void flush_scheduled_work(void)
559 flush_workqueue(system_wq);
563 * schedule_delayed_work_on - queue work in global workqueue on CPU after delay
565 * @dwork: job to be done
566 * @delay: number of jiffies to wait
568 * After waiting for a given time this puts a job in the kernel-global
569 * workqueue on the specified CPU.
571 static inline bool schedule_delayed_work_on(int cpu, struct delayed_work *dwork,
574 return queue_delayed_work_on(cpu, system_wq, dwork, delay);
578 * schedule_delayed_work - put work task in global workqueue after delay
579 * @dwork: job to be done
580 * @delay: number of jiffies to wait or 0 for immediate execution
582 * After waiting for a given time this puts a job in the kernel-global
585 static inline bool schedule_delayed_work(struct delayed_work *dwork,
588 return queue_delayed_work(system_wq, dwork, delay);
592 * keventd_up - is workqueue initialized yet?
594 static inline bool keventd_up(void)
596 return system_wq != NULL;
600 static inline long work_on_cpu(int cpu, long (*fn)(void *), void *arg)
605 long work_on_cpu(int cpu, long (*fn)(void *), void *arg);
606 #endif /* CONFIG_SMP */
608 #ifdef CONFIG_FREEZER
609 extern void freeze_workqueues_begin(void);
610 extern bool freeze_workqueues_busy(void);
611 extern void thaw_workqueues(void);
612 #endif /* CONFIG_FREEZER */
615 int workqueue_sysfs_register(struct workqueue_struct *wq);
616 #else /* CONFIG_SYSFS */
617 static inline int workqueue_sysfs_register(struct workqueue_struct *wq)
619 #endif /* CONFIG_SYSFS */