1 #ifndef _LINUX_WAIT_H
2 #define _LINUX_WAIT_H
3 /*
4 * Linux wait queue related types and methods
5 */
6 #include <linux/list.h>
7 #include <linux/stddef.h>
8 #include <linux/spinlock.h>
9 #include <asm/current.h>
10 #include <uapi/linux/wait.h>
11
12 typedef struct __wait_queue wait_queue_t;
13 typedef int (*wait_queue_func_t)(wait_queue_t *wait, unsigned mode, int flags, void *key);
14 int default_wake_function(wait_queue_t *wait, unsigned mode, int flags, void *key);
15
16 /* __wait_queue::flags */
17 #define WQ_FLAG_EXCLUSIVE 0x01
18 #define WQ_FLAG_WOKEN 0x02
19
20 struct __wait_queue {
21 unsigned int flags;
22 void *private;
23 wait_queue_func_t func;
24 struct list_head task_list;
25 };
26
27 struct wait_bit_key {
28 void *flags;
29 int bit_nr;
30 #define WAIT_ATOMIC_T_BIT_NR -1
31 unsigned long timeout;
32 };
33
34 struct wait_bit_queue {
35 struct wait_bit_key key;
36 wait_queue_t wait;
37 };
38
39 struct __wait_queue_head {
40 spinlock_t lock;
41 struct list_head task_list;
42 };
43 typedef struct __wait_queue_head wait_queue_head_t;
44
45 struct task_struct;
46
47 /*
48 * Macros for declaration and initialisaton of the datatypes
49 */
50
51 #define __WAITQUEUE_INITIALIZER(name, tsk) { \
52 .private = tsk, \
53 .func = default_wake_function, \
54 .task_list = { NULL, NULL } }
55
56 #define DECLARE_WAITQUEUE(name, tsk) \
57 wait_queue_t name = __WAITQUEUE_INITIALIZER(name, tsk)
58
59 #define __WAIT_QUEUE_HEAD_INITIALIZER(name) { \
60 .lock = __SPIN_LOCK_UNLOCKED(name.lock), \
61 .task_list = { &(name).task_list, &(name).task_list } }
62
63 #define DECLARE_WAIT_QUEUE_HEAD(name) \
64 wait_queue_head_t name = __WAIT_QUEUE_HEAD_INITIALIZER(name)
65
66 #define __WAIT_BIT_KEY_INITIALIZER(word, bit) \
67 { .flags = word, .bit_nr = bit, }
68
69 #define __WAIT_ATOMIC_T_KEY_INITIALIZER(p) \
70 { .flags = p, .bit_nr = WAIT_ATOMIC_T_BIT_NR, }
71
72 extern void __init_waitqueue_head(wait_queue_head_t *q, const char *name, struct lock_class_key *);
73
74 #define init_waitqueue_head(q) \
75 do { \
76 static struct lock_class_key __key; \
77 \
78 __init_waitqueue_head((q), #q, &__key); \
79 } while (0)
80
81 #ifdef CONFIG_LOCKDEP
82 # define __WAIT_QUEUE_HEAD_INIT_ONSTACK(name) \
83 ({ init_waitqueue_head(&name); name; })
84 # define DECLARE_WAIT_QUEUE_HEAD_ONSTACK(name) \
85 wait_queue_head_t name = __WAIT_QUEUE_HEAD_INIT_ONSTACK(name)
86 #else
87 # define DECLARE_WAIT_QUEUE_HEAD_ONSTACK(name) DECLARE_WAIT_QUEUE_HEAD(name)
88 #endif
89
init_waitqueue_entry(wait_queue_t * q,struct task_struct * p)90 static inline void init_waitqueue_entry(wait_queue_t *q, struct task_struct *p)
91 {
92 q->flags = 0;
93 q->private = p;
94 q->func = default_wake_function;
95 }
96
97 static inline void
init_waitqueue_func_entry(wait_queue_t * q,wait_queue_func_t func)98 init_waitqueue_func_entry(wait_queue_t *q, wait_queue_func_t func)
99 {
100 q->flags = 0;
101 q->private = NULL;
102 q->func = func;
103 }
104
105 /**
106 * waitqueue_active -- locklessly test for waiters on the queue
107 * @q: the waitqueue to test for waiters
108 *
109 * returns true if the wait list is not empty
110 *
111 * NOTE: this function is lockless and requires care, incorrect usage _will_
112 * lead to sporadic and non-obvious failure.
113 *
114 * Use either while holding wait_queue_head_t::lock or when used for wakeups
115 * with an extra smp_mb() like:
116 *
117 * CPU0 - waker CPU1 - waiter
118 *
119 * for (;;) {
120 * @cond = true; prepare_to_wait(&wq, &wait, state);
121 * smp_mb(); // smp_mb() from set_current_state()
122 * if (waitqueue_active(wq)) if (@cond)
123 * wake_up(wq); break;
124 * schedule();
125 * }
126 * finish_wait(&wq, &wait);
127 *
128 * Because without the explicit smp_mb() it's possible for the
129 * waitqueue_active() load to get hoisted over the @cond store such that we'll
130 * observe an empty wait list while the waiter might not observe @cond.
131 *
132 * Also note that this 'optimization' trades a spin_lock() for an smp_mb(),
133 * which (when the lock is uncontended) are of roughly equal cost.
134 */
waitqueue_active(wait_queue_head_t * q)135 static inline int waitqueue_active(wait_queue_head_t *q)
136 {
137 return !list_empty(&q->task_list);
138 }
139
140 /**
141 * wq_has_sleeper - check if there are any waiting processes
142 * @wq: wait queue head
143 *
144 * Returns true if wq has waiting processes
145 *
146 * Please refer to the comment for waitqueue_active.
147 */
wq_has_sleeper(wait_queue_head_t * wq)148 static inline bool wq_has_sleeper(wait_queue_head_t *wq)
149 {
150 /*
151 * We need to be sure we are in sync with the
152 * add_wait_queue modifications to the wait queue.
153 *
154 * This memory barrier should be paired with one on the
155 * waiting side.
156 */
157 smp_mb();
158 return waitqueue_active(wq);
159 }
160
161 extern void add_wait_queue(wait_queue_head_t *q, wait_queue_t *wait);
162 extern void add_wait_queue_exclusive(wait_queue_head_t *q, wait_queue_t *wait);
163 extern void remove_wait_queue(wait_queue_head_t *q, wait_queue_t *wait);
164
__add_wait_queue(wait_queue_head_t * head,wait_queue_t * new)165 static inline void __add_wait_queue(wait_queue_head_t *head, wait_queue_t *new)
166 {
167 list_add(&new->task_list, &head->task_list);
168 }
169
170 /*
171 * Used for wake-one threads:
172 */
173 static inline void
__add_wait_queue_exclusive(wait_queue_head_t * q,wait_queue_t * wait)174 __add_wait_queue_exclusive(wait_queue_head_t *q, wait_queue_t *wait)
175 {
176 wait->flags |= WQ_FLAG_EXCLUSIVE;
177 __add_wait_queue(q, wait);
178 }
179
__add_wait_queue_tail(wait_queue_head_t * head,wait_queue_t * new)180 static inline void __add_wait_queue_tail(wait_queue_head_t *head,
181 wait_queue_t *new)
182 {
183 list_add_tail(&new->task_list, &head->task_list);
184 }
185
186 static inline void
__add_wait_queue_tail_exclusive(wait_queue_head_t * q,wait_queue_t * wait)187 __add_wait_queue_tail_exclusive(wait_queue_head_t *q, wait_queue_t *wait)
188 {
189 wait->flags |= WQ_FLAG_EXCLUSIVE;
190 __add_wait_queue_tail(q, wait);
191 }
192
193 static inline void
__remove_wait_queue(wait_queue_head_t * head,wait_queue_t * old)194 __remove_wait_queue(wait_queue_head_t *head, wait_queue_t *old)
195 {
196 list_del(&old->task_list);
197 }
198
199 typedef int wait_bit_action_f(struct wait_bit_key *, int mode);
200 void __wake_up(wait_queue_head_t *q, unsigned int mode, int nr, void *key);
201 void __wake_up_locked_key(wait_queue_head_t *q, unsigned int mode, void *key);
202 void __wake_up_sync_key(wait_queue_head_t *q, unsigned int mode, int nr, void *key);
203 void __wake_up_locked(wait_queue_head_t *q, unsigned int mode, int nr);
204 void __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr);
205 void __wake_up_bit(wait_queue_head_t *, void *, int);
206 int __wait_on_bit(wait_queue_head_t *, struct wait_bit_queue *, wait_bit_action_f *, unsigned);
207 int __wait_on_bit_lock(wait_queue_head_t *, struct wait_bit_queue *, wait_bit_action_f *, unsigned);
208 void wake_up_bit(void *, int);
209 void wake_up_atomic_t(atomic_t *);
210 int out_of_line_wait_on_bit(void *, int, wait_bit_action_f *, unsigned);
211 int out_of_line_wait_on_bit_timeout(void *, int, wait_bit_action_f *, unsigned, unsigned long);
212 int out_of_line_wait_on_bit_lock(void *, int, wait_bit_action_f *, unsigned);
213 int out_of_line_wait_on_atomic_t(atomic_t *, int (*)(atomic_t *), unsigned);
214 wait_queue_head_t *bit_waitqueue(void *, int);
215
216 #define wake_up(x) __wake_up(x, TASK_NORMAL, 1, NULL)
217 #define wake_up_nr(x, nr) __wake_up(x, TASK_NORMAL, nr, NULL)
218 #define wake_up_all(x) __wake_up(x, TASK_NORMAL, 0, NULL)
219 #define wake_up_locked(x) __wake_up_locked((x), TASK_NORMAL, 1)
220 #define wake_up_all_locked(x) __wake_up_locked((x), TASK_NORMAL, 0)
221
222 #define wake_up_interruptible(x) __wake_up(x, TASK_INTERRUPTIBLE, 1, NULL)
223 #define wake_up_interruptible_nr(x, nr) __wake_up(x, TASK_INTERRUPTIBLE, nr, NULL)
224 #define wake_up_interruptible_all(x) __wake_up(x, TASK_INTERRUPTIBLE, 0, NULL)
225 #define wake_up_interruptible_sync(x) __wake_up_sync((x), TASK_INTERRUPTIBLE, 1)
226
227 /*
228 * Wakeup macros to be used to report events to the targets.
229 */
230 #define wake_up_poll(x, m) \
231 __wake_up(x, TASK_NORMAL, 1, (void *) (m))
232 #define wake_up_locked_poll(x, m) \
233 __wake_up_locked_key((x), TASK_NORMAL, (void *) (m))
234 #define wake_up_interruptible_poll(x, m) \
235 __wake_up(x, TASK_INTERRUPTIBLE, 1, (void *) (m))
236 #define wake_up_interruptible_sync_poll(x, m) \
237 __wake_up_sync_key((x), TASK_INTERRUPTIBLE, 1, (void *) (m))
238
239 #define ___wait_cond_timeout(condition) \
240 ({ \
241 bool __cond = (condition); \
242 if (__cond && !__ret) \
243 __ret = 1; \
244 __cond || !__ret; \
245 })
246
247 #define ___wait_is_interruptible(state) \
248 (!__builtin_constant_p(state) || \
249 state == TASK_INTERRUPTIBLE || state == TASK_KILLABLE) \
250
251 extern void init_wait_entry(wait_queue_t *__wait, int flags);
252
253 /*
254 * The below macro ___wait_event() has an explicit shadow of the __ret
255 * variable when used from the wait_event_*() macros.
256 *
257 * This is so that both can use the ___wait_cond_timeout() construct
258 * to wrap the condition.
259 *
260 * The type inconsistency of the wait_event_*() __ret variable is also
261 * on purpose; we use long where we can return timeout values and int
262 * otherwise.
263 */
264
265 #define ___wait_event(wq, condition, state, exclusive, ret, cmd) \
266 ({ \
267 __label__ __out; \
268 wait_queue_t __wait; \
269 long __ret = ret; /* explicit shadow */ \
270 \
271 init_wait_entry(&__wait, exclusive ? WQ_FLAG_EXCLUSIVE : 0); \
272 for (;;) { \
273 long __int = prepare_to_wait_event(&wq, &__wait, state);\
274 \
275 if (condition) \
276 break; \
277 \
278 if (___wait_is_interruptible(state) && __int) { \
279 __ret = __int; \
280 goto __out; \
281 } \
282 \
283 cmd; \
284 } \
285 finish_wait(&wq, &__wait); \
286 __out: __ret; \
287 })
288
289 #define __wait_event(wq, condition) \
290 (void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0, 0, \
291 schedule())
292
293 /**
294 * wait_event - sleep until a condition gets true
295 * @wq: the waitqueue to wait on
296 * @condition: a C expression for the event to wait for
297 *
298 * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
299 * @condition evaluates to true. The @condition is checked each time
300 * the waitqueue @wq is woken up.
301 *
302 * wake_up() has to be called after changing any variable that could
303 * change the result of the wait condition.
304 */
305 #define wait_event(wq, condition) \
306 do { \
307 might_sleep(); \
308 if (condition) \
309 break; \
310 __wait_event(wq, condition); \
311 } while (0)
312
313 #define __io_wait_event(wq, condition) \
314 (void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0, 0, \
315 io_schedule())
316
317 /*
318 * io_wait_event() -- like wait_event() but with io_schedule()
319 */
320 #define io_wait_event(wq, condition) \
321 do { \
322 might_sleep(); \
323 if (condition) \
324 break; \
325 __io_wait_event(wq, condition); \
326 } while (0)
327
328 #define __wait_event_freezable(wq, condition) \
329 ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 0, 0, \
330 schedule(); try_to_freeze())
331
332 /**
333 * wait_event_freezable - sleep (or freeze) until a condition gets true
334 * @wq: the waitqueue to wait on
335 * @condition: a C expression for the event to wait for
336 *
337 * The process is put to sleep (TASK_INTERRUPTIBLE -- so as not to contribute
338 * to system load) until the @condition evaluates to true. The
339 * @condition is checked each time the waitqueue @wq is woken up.
340 *
341 * wake_up() has to be called after changing any variable that could
342 * change the result of the wait condition.
343 */
344 #define wait_event_freezable(wq, condition) \
345 ({ \
346 int __ret = 0; \
347 might_sleep(); \
348 if (!(condition)) \
349 __ret = __wait_event_freezable(wq, condition); \
350 __ret; \
351 })
352
353 #define __wait_event_timeout(wq, condition, timeout) \
354 ___wait_event(wq, ___wait_cond_timeout(condition), \
355 TASK_UNINTERRUPTIBLE, 0, timeout, \
356 __ret = schedule_timeout(__ret))
357
358 /**
359 * wait_event_timeout - sleep until a condition gets true or a timeout elapses
360 * @wq: the waitqueue to wait on
361 * @condition: a C expression for the event to wait for
362 * @timeout: timeout, in jiffies
363 *
364 * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
365 * @condition evaluates to true. The @condition is checked each time
366 * the waitqueue @wq is woken up.
367 *
368 * wake_up() has to be called after changing any variable that could
369 * change the result of the wait condition.
370 *
371 * Returns:
372 * 0 if the @condition evaluated to %false after the @timeout elapsed,
373 * 1 if the @condition evaluated to %true after the @timeout elapsed,
374 * or the remaining jiffies (at least 1) if the @condition evaluated
375 * to %true before the @timeout elapsed.
376 */
377 #define wait_event_timeout(wq, condition, timeout) \
378 ({ \
379 long __ret = timeout; \
380 might_sleep(); \
381 if (!___wait_cond_timeout(condition)) \
382 __ret = __wait_event_timeout(wq, condition, timeout); \
383 __ret; \
384 })
385
386 #define __wait_event_freezable_timeout(wq, condition, timeout) \
387 ___wait_event(wq, ___wait_cond_timeout(condition), \
388 TASK_INTERRUPTIBLE, 0, timeout, \
389 __ret = schedule_timeout(__ret); try_to_freeze())
390
391 /*
392 * like wait_event_timeout() -- except it uses TASK_INTERRUPTIBLE to avoid
393 * increasing load and is freezable.
394 */
395 #define wait_event_freezable_timeout(wq, condition, timeout) \
396 ({ \
397 long __ret = timeout; \
398 might_sleep(); \
399 if (!___wait_cond_timeout(condition)) \
400 __ret = __wait_event_freezable_timeout(wq, condition, timeout); \
401 __ret; \
402 })
403
404 #define __wait_event_exclusive_cmd(wq, condition, cmd1, cmd2) \
405 (void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 1, 0, \
406 cmd1; schedule(); cmd2)
407 /*
408 * Just like wait_event_cmd(), except it sets exclusive flag
409 */
410 #define wait_event_exclusive_cmd(wq, condition, cmd1, cmd2) \
411 do { \
412 if (condition) \
413 break; \
414 __wait_event_exclusive_cmd(wq, condition, cmd1, cmd2); \
415 } while (0)
416
417 #define __wait_event_cmd(wq, condition, cmd1, cmd2) \
418 (void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0, 0, \
419 cmd1; schedule(); cmd2)
420
421 /**
422 * wait_event_cmd - sleep until a condition gets true
423 * @wq: the waitqueue to wait on
424 * @condition: a C expression for the event to wait for
425 * @cmd1: the command will be executed before sleep
426 * @cmd2: the command will be executed after sleep
427 *
428 * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
429 * @condition evaluates to true. The @condition is checked each time
430 * the waitqueue @wq is woken up.
431 *
432 * wake_up() has to be called after changing any variable that could
433 * change the result of the wait condition.
434 */
435 #define wait_event_cmd(wq, condition, cmd1, cmd2) \
436 do { \
437 if (condition) \
438 break; \
439 __wait_event_cmd(wq, condition, cmd1, cmd2); \
440 } while (0)
441
442 #define __wait_event_interruptible(wq, condition) \
443 ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 0, 0, \
444 schedule())
445
446 /**
447 * wait_event_interruptible - sleep until a condition gets true
448 * @wq: the waitqueue to wait on
449 * @condition: a C expression for the event to wait for
450 *
451 * The process is put to sleep (TASK_INTERRUPTIBLE) until the
452 * @condition evaluates to true or a signal is received.
453 * The @condition is checked each time the waitqueue @wq is woken up.
454 *
455 * wake_up() has to be called after changing any variable that could
456 * change the result of the wait condition.
457 *
458 * The function will return -ERESTARTSYS if it was interrupted by a
459 * signal and 0 if @condition evaluated to true.
460 */
461 #define wait_event_interruptible(wq, condition) \
462 ({ \
463 int __ret = 0; \
464 might_sleep(); \
465 if (!(condition)) \
466 __ret = __wait_event_interruptible(wq, condition); \
467 __ret; \
468 })
469
470 #define __wait_event_interruptible_timeout(wq, condition, timeout) \
471 ___wait_event(wq, ___wait_cond_timeout(condition), \
472 TASK_INTERRUPTIBLE, 0, timeout, \
473 __ret = schedule_timeout(__ret))
474
475 /**
476 * wait_event_interruptible_timeout - sleep until a condition gets true or a timeout elapses
477 * @wq: the waitqueue to wait on
478 * @condition: a C expression for the event to wait for
479 * @timeout: timeout, in jiffies
480 *
481 * The process is put to sleep (TASK_INTERRUPTIBLE) until the
482 * @condition evaluates to true or a signal is received.
483 * The @condition is checked each time the waitqueue @wq is woken up.
484 *
485 * wake_up() has to be called after changing any variable that could
486 * change the result of the wait condition.
487 *
488 * Returns:
489 * 0 if the @condition evaluated to %false after the @timeout elapsed,
490 * 1 if the @condition evaluated to %true after the @timeout elapsed,
491 * the remaining jiffies (at least 1) if the @condition evaluated
492 * to %true before the @timeout elapsed, or -%ERESTARTSYS if it was
493 * interrupted by a signal.
494 */
495 #define wait_event_interruptible_timeout(wq, condition, timeout) \
496 ({ \
497 long __ret = timeout; \
498 might_sleep(); \
499 if (!___wait_cond_timeout(condition)) \
500 __ret = __wait_event_interruptible_timeout(wq, \
501 condition, timeout); \
502 __ret; \
503 })
504
505 #define __wait_event_hrtimeout(wq, condition, timeout, state) \
506 ({ \
507 int __ret = 0; \
508 struct hrtimer_sleeper __t; \
509 \
510 hrtimer_init_on_stack(&__t.timer, CLOCK_MONOTONIC, \
511 HRTIMER_MODE_REL); \
512 hrtimer_init_sleeper(&__t, current); \
513 if ((timeout).tv64 != KTIME_MAX) \
514 hrtimer_start_range_ns(&__t.timer, timeout, \
515 current->timer_slack_ns, \
516 HRTIMER_MODE_REL); \
517 \
518 __ret = ___wait_event(wq, condition, state, 0, 0, \
519 if (!__t.task) { \
520 __ret = -ETIME; \
521 break; \
522 } \
523 schedule()); \
524 \
525 hrtimer_cancel(&__t.timer); \
526 destroy_hrtimer_on_stack(&__t.timer); \
527 __ret; \
528 })
529
530 /**
531 * wait_event_hrtimeout - sleep until a condition gets true or a timeout elapses
532 * @wq: the waitqueue to wait on
533 * @condition: a C expression for the event to wait for
534 * @timeout: timeout, as a ktime_t
535 *
536 * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
537 * @condition evaluates to true or a signal is received.
538 * The @condition is checked each time the waitqueue @wq is woken up.
539 *
540 * wake_up() has to be called after changing any variable that could
541 * change the result of the wait condition.
542 *
543 * The function returns 0 if @condition became true, or -ETIME if the timeout
544 * elapsed.
545 */
546 #define wait_event_hrtimeout(wq, condition, timeout) \
547 ({ \
548 int __ret = 0; \
549 might_sleep(); \
550 if (!(condition)) \
551 __ret = __wait_event_hrtimeout(wq, condition, timeout, \
552 TASK_UNINTERRUPTIBLE); \
553 __ret; \
554 })
555
556 /**
557 * wait_event_interruptible_hrtimeout - sleep until a condition gets true or a timeout elapses
558 * @wq: the waitqueue to wait on
559 * @condition: a C expression for the event to wait for
560 * @timeout: timeout, as a ktime_t
561 *
562 * The process is put to sleep (TASK_INTERRUPTIBLE) until the
563 * @condition evaluates to true or a signal is received.
564 * The @condition is checked each time the waitqueue @wq is woken up.
565 *
566 * wake_up() has to be called after changing any variable that could
567 * change the result of the wait condition.
568 *
569 * The function returns 0 if @condition became true, -ERESTARTSYS if it was
570 * interrupted by a signal, or -ETIME if the timeout elapsed.
571 */
572 #define wait_event_interruptible_hrtimeout(wq, condition, timeout) \
573 ({ \
574 long __ret = 0; \
575 might_sleep(); \
576 if (!(condition)) \
577 __ret = __wait_event_hrtimeout(wq, condition, timeout, \
578 TASK_INTERRUPTIBLE); \
579 __ret; \
580 })
581
582 #define __wait_event_interruptible_exclusive(wq, condition) \
583 ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 1, 0, \
584 schedule())
585
586 #define wait_event_interruptible_exclusive(wq, condition) \
587 ({ \
588 int __ret = 0; \
589 might_sleep(); \
590 if (!(condition)) \
591 __ret = __wait_event_interruptible_exclusive(wq, condition);\
592 __ret; \
593 })
594
595 #define __wait_event_killable_exclusive(wq, condition) \
596 ___wait_event(wq, condition, TASK_KILLABLE, 1, 0, \
597 schedule())
598
599 #define wait_event_killable_exclusive(wq, condition) \
600 ({ \
601 int __ret = 0; \
602 might_sleep(); \
603 if (!(condition)) \
604 __ret = __wait_event_killable_exclusive(wq, condition); \
605 __ret; \
606 })
607
608
609 #define __wait_event_freezable_exclusive(wq, condition) \
610 ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 1, 0, \
611 schedule(); try_to_freeze())
612
613 #define wait_event_freezable_exclusive(wq, condition) \
614 ({ \
615 int __ret = 0; \
616 might_sleep(); \
617 if (!(condition)) \
618 __ret = __wait_event_freezable_exclusive(wq, condition);\
619 __ret; \
620 })
621
622
623 #define __wait_event_interruptible_locked(wq, condition, exclusive, irq) \
624 ({ \
625 int __ret = 0; \
626 DEFINE_WAIT(__wait); \
627 if (exclusive) \
628 __wait.flags |= WQ_FLAG_EXCLUSIVE; \
629 do { \
630 if (likely(list_empty(&__wait.task_list))) \
631 __add_wait_queue_tail(&(wq), &__wait); \
632 set_current_state(TASK_INTERRUPTIBLE); \
633 if (signal_pending(current)) { \
634 __ret = -ERESTARTSYS; \
635 break; \
636 } \
637 if (irq) \
638 spin_unlock_irq(&(wq).lock); \
639 else \
640 spin_unlock(&(wq).lock); \
641 schedule(); \
642 if (irq) \
643 spin_lock_irq(&(wq).lock); \
644 else \
645 spin_lock(&(wq).lock); \
646 } while (!(condition)); \
647 __remove_wait_queue(&(wq), &__wait); \
648 __set_current_state(TASK_RUNNING); \
649 __ret; \
650 })
651
652
653 /**
654 * wait_event_interruptible_locked - sleep until a condition gets true
655 * @wq: the waitqueue to wait on
656 * @condition: a C expression for the event to wait for
657 *
658 * The process is put to sleep (TASK_INTERRUPTIBLE) until the
659 * @condition evaluates to true or a signal is received.
660 * The @condition is checked each time the waitqueue @wq is woken up.
661 *
662 * It must be called with wq.lock being held. This spinlock is
663 * unlocked while sleeping but @condition testing is done while lock
664 * is held and when this macro exits the lock is held.
665 *
666 * The lock is locked/unlocked using spin_lock()/spin_unlock()
667 * functions which must match the way they are locked/unlocked outside
668 * of this macro.
669 *
670 * wake_up_locked() has to be called after changing any variable that could
671 * change the result of the wait condition.
672 *
673 * The function will return -ERESTARTSYS if it was interrupted by a
674 * signal and 0 if @condition evaluated to true.
675 */
676 #define wait_event_interruptible_locked(wq, condition) \
677 ((condition) \
678 ? 0 : __wait_event_interruptible_locked(wq, condition, 0, 0))
679
680 /**
681 * wait_event_interruptible_locked_irq - sleep until a condition gets true
682 * @wq: the waitqueue to wait on
683 * @condition: a C expression for the event to wait for
684 *
685 * The process is put to sleep (TASK_INTERRUPTIBLE) until the
686 * @condition evaluates to true or a signal is received.
687 * The @condition is checked each time the waitqueue @wq is woken up.
688 *
689 * It must be called with wq.lock being held. This spinlock is
690 * unlocked while sleeping but @condition testing is done while lock
691 * is held and when this macro exits the lock is held.
692 *
693 * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq()
694 * functions which must match the way they are locked/unlocked outside
695 * of this macro.
696 *
697 * wake_up_locked() has to be called after changing any variable that could
698 * change the result of the wait condition.
699 *
700 * The function will return -ERESTARTSYS if it was interrupted by a
701 * signal and 0 if @condition evaluated to true.
702 */
703 #define wait_event_interruptible_locked_irq(wq, condition) \
704 ((condition) \
705 ? 0 : __wait_event_interruptible_locked(wq, condition, 0, 1))
706
707 /**
708 * wait_event_interruptible_exclusive_locked - sleep exclusively until a condition gets true
709 * @wq: the waitqueue to wait on
710 * @condition: a C expression for the event to wait for
711 *
712 * The process is put to sleep (TASK_INTERRUPTIBLE) until the
713 * @condition evaluates to true or a signal is received.
714 * The @condition is checked each time the waitqueue @wq is woken up.
715 *
716 * It must be called with wq.lock being held. This spinlock is
717 * unlocked while sleeping but @condition testing is done while lock
718 * is held and when this macro exits the lock is held.
719 *
720 * The lock is locked/unlocked using spin_lock()/spin_unlock()
721 * functions which must match the way they are locked/unlocked outside
722 * of this macro.
723 *
724 * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
725 * set thus when other process waits process on the list if this
726 * process is awaken further processes are not considered.
727 *
728 * wake_up_locked() has to be called after changing any variable that could
729 * change the result of the wait condition.
730 *
731 * The function will return -ERESTARTSYS if it was interrupted by a
732 * signal and 0 if @condition evaluated to true.
733 */
734 #define wait_event_interruptible_exclusive_locked(wq, condition) \
735 ((condition) \
736 ? 0 : __wait_event_interruptible_locked(wq, condition, 1, 0))
737
738 /**
739 * wait_event_interruptible_exclusive_locked_irq - sleep until a condition gets true
740 * @wq: the waitqueue to wait on
741 * @condition: a C expression for the event to wait for
742 *
743 * The process is put to sleep (TASK_INTERRUPTIBLE) until the
744 * @condition evaluates to true or a signal is received.
745 * The @condition is checked each time the waitqueue @wq is woken up.
746 *
747 * It must be called with wq.lock being held. This spinlock is
748 * unlocked while sleeping but @condition testing is done while lock
749 * is held and when this macro exits the lock is held.
750 *
751 * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq()
752 * functions which must match the way they are locked/unlocked outside
753 * of this macro.
754 *
755 * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
756 * set thus when other process waits process on the list if this
757 * process is awaken further processes are not considered.
758 *
759 * wake_up_locked() has to be called after changing any variable that could
760 * change the result of the wait condition.
761 *
762 * The function will return -ERESTARTSYS if it was interrupted by a
763 * signal and 0 if @condition evaluated to true.
764 */
765 #define wait_event_interruptible_exclusive_locked_irq(wq, condition) \
766 ((condition) \
767 ? 0 : __wait_event_interruptible_locked(wq, condition, 1, 1))
768
769
770 #define __wait_event_killable(wq, condition) \
771 ___wait_event(wq, condition, TASK_KILLABLE, 0, 0, schedule())
772
773 /**
774 * wait_event_killable - sleep until a condition gets true
775 * @wq: the waitqueue to wait on
776 * @condition: a C expression for the event to wait for
777 *
778 * The process is put to sleep (TASK_KILLABLE) until the
779 * @condition evaluates to true or a signal is received.
780 * The @condition is checked each time the waitqueue @wq is woken up.
781 *
782 * wake_up() has to be called after changing any variable that could
783 * change the result of the wait condition.
784 *
785 * The function will return -ERESTARTSYS if it was interrupted by a
786 * signal and 0 if @condition evaluated to true.
787 */
788 #define wait_event_killable(wq, condition) \
789 ({ \
790 int __ret = 0; \
791 might_sleep(); \
792 if (!(condition)) \
793 __ret = __wait_event_killable(wq, condition); \
794 __ret; \
795 })
796
797
798 #define __wait_event_lock_irq(wq, condition, lock, cmd) \
799 (void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0, 0, \
800 spin_unlock_irq(&lock); \
801 cmd; \
802 schedule(); \
803 spin_lock_irq(&lock))
804
805 /**
806 * wait_event_lock_irq_cmd - sleep until a condition gets true. The
807 * condition is checked under the lock. This
808 * is expected to be called with the lock
809 * taken.
810 * @wq: the waitqueue to wait on
811 * @condition: a C expression for the event to wait for
812 * @lock: a locked spinlock_t, which will be released before cmd
813 * and schedule() and reacquired afterwards.
814 * @cmd: a command which is invoked outside the critical section before
815 * sleep
816 *
817 * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
818 * @condition evaluates to true. The @condition is checked each time
819 * the waitqueue @wq is woken up.
820 *
821 * wake_up() has to be called after changing any variable that could
822 * change the result of the wait condition.
823 *
824 * This is supposed to be called while holding the lock. The lock is
825 * dropped before invoking the cmd and going to sleep and is reacquired
826 * afterwards.
827 */
828 #define wait_event_lock_irq_cmd(wq, condition, lock, cmd) \
829 do { \
830 if (condition) \
831 break; \
832 __wait_event_lock_irq(wq, condition, lock, cmd); \
833 } while (0)
834
835 /**
836 * wait_event_lock_irq - sleep until a condition gets true. The
837 * condition is checked under the lock. This
838 * is expected to be called with the lock
839 * taken.
840 * @wq: the waitqueue to wait on
841 * @condition: a C expression for the event to wait for
842 * @lock: a locked spinlock_t, which will be released before schedule()
843 * and reacquired afterwards.
844 *
845 * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
846 * @condition evaluates to true. The @condition is checked each time
847 * the waitqueue @wq is woken up.
848 *
849 * wake_up() has to be called after changing any variable that could
850 * change the result of the wait condition.
851 *
852 * This is supposed to be called while holding the lock. The lock is
853 * dropped before going to sleep and is reacquired afterwards.
854 */
855 #define wait_event_lock_irq(wq, condition, lock) \
856 do { \
857 if (condition) \
858 break; \
859 __wait_event_lock_irq(wq, condition, lock, ); \
860 } while (0)
861
862
863 #define __wait_event_interruptible_lock_irq(wq, condition, lock, cmd) \
864 ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 0, 0, \
865 spin_unlock_irq(&lock); \
866 cmd; \
867 schedule(); \
868 spin_lock_irq(&lock))
869
870 /**
871 * wait_event_interruptible_lock_irq_cmd - sleep until a condition gets true.
872 * The condition is checked under the lock. This is expected to
873 * be called with the lock taken.
874 * @wq: the waitqueue to wait on
875 * @condition: a C expression for the event to wait for
876 * @lock: a locked spinlock_t, which will be released before cmd and
877 * schedule() and reacquired afterwards.
878 * @cmd: a command which is invoked outside the critical section before
879 * sleep
880 *
881 * The process is put to sleep (TASK_INTERRUPTIBLE) until the
882 * @condition evaluates to true or a signal is received. The @condition is
883 * checked each time the waitqueue @wq is woken up.
884 *
885 * wake_up() has to be called after changing any variable that could
886 * change the result of the wait condition.
887 *
888 * This is supposed to be called while holding the lock. The lock is
889 * dropped before invoking the cmd and going to sleep and is reacquired
890 * afterwards.
891 *
892 * The macro will return -ERESTARTSYS if it was interrupted by a signal
893 * and 0 if @condition evaluated to true.
894 */
895 #define wait_event_interruptible_lock_irq_cmd(wq, condition, lock, cmd) \
896 ({ \
897 int __ret = 0; \
898 if (!(condition)) \
899 __ret = __wait_event_interruptible_lock_irq(wq, \
900 condition, lock, cmd); \
901 __ret; \
902 })
903
904 /**
905 * wait_event_interruptible_lock_irq - sleep until a condition gets true.
906 * The condition is checked under the lock. This is expected
907 * to be called with the lock taken.
908 * @wq: the waitqueue to wait on
909 * @condition: a C expression for the event to wait for
910 * @lock: a locked spinlock_t, which will be released before schedule()
911 * and reacquired afterwards.
912 *
913 * The process is put to sleep (TASK_INTERRUPTIBLE) until the
914 * @condition evaluates to true or signal is received. The @condition is
915 * checked each time the waitqueue @wq is woken up.
916 *
917 * wake_up() has to be called after changing any variable that could
918 * change the result of the wait condition.
919 *
920 * This is supposed to be called while holding the lock. The lock is
921 * dropped before going to sleep and is reacquired afterwards.
922 *
923 * The macro will return -ERESTARTSYS if it was interrupted by a signal
924 * and 0 if @condition evaluated to true.
925 */
926 #define wait_event_interruptible_lock_irq(wq, condition, lock) \
927 ({ \
928 int __ret = 0; \
929 if (!(condition)) \
930 __ret = __wait_event_interruptible_lock_irq(wq, \
931 condition, lock,); \
932 __ret; \
933 })
934
935 #define __wait_event_interruptible_lock_irq_timeout(wq, condition, \
936 lock, timeout) \
937 ___wait_event(wq, ___wait_cond_timeout(condition), \
938 TASK_INTERRUPTIBLE, 0, timeout, \
939 spin_unlock_irq(&lock); \
940 __ret = schedule_timeout(__ret); \
941 spin_lock_irq(&lock));
942
943 /**
944 * wait_event_interruptible_lock_irq_timeout - sleep until a condition gets
945 * true or a timeout elapses. The condition is checked under
946 * the lock. This is expected to be called with the lock taken.
947 * @wq: the waitqueue to wait on
948 * @condition: a C expression for the event to wait for
949 * @lock: a locked spinlock_t, which will be released before schedule()
950 * and reacquired afterwards.
951 * @timeout: timeout, in jiffies
952 *
953 * The process is put to sleep (TASK_INTERRUPTIBLE) until the
954 * @condition evaluates to true or signal is received. The @condition is
955 * checked each time the waitqueue @wq is woken up.
956 *
957 * wake_up() has to be called after changing any variable that could
958 * change the result of the wait condition.
959 *
960 * This is supposed to be called while holding the lock. The lock is
961 * dropped before going to sleep and is reacquired afterwards.
962 *
963 * The function returns 0 if the @timeout elapsed, -ERESTARTSYS if it
964 * was interrupted by a signal, and the remaining jiffies otherwise
965 * if the condition evaluated to true before the timeout elapsed.
966 */
967 #define wait_event_interruptible_lock_irq_timeout(wq, condition, lock, \
968 timeout) \
969 ({ \
970 long __ret = timeout; \
971 if (!___wait_cond_timeout(condition)) \
972 __ret = __wait_event_interruptible_lock_irq_timeout( \
973 wq, condition, lock, timeout); \
974 __ret; \
975 })
976
977 /*
978 * Waitqueues which are removed from the waitqueue_head at wakeup time
979 */
980 void prepare_to_wait(wait_queue_head_t *q, wait_queue_t *wait, int state);
981 void prepare_to_wait_exclusive(wait_queue_head_t *q, wait_queue_t *wait, int state);
982 long prepare_to_wait_event(wait_queue_head_t *q, wait_queue_t *wait, int state);
983 void finish_wait(wait_queue_head_t *q, wait_queue_t *wait);
984 long wait_woken(wait_queue_t *wait, unsigned mode, long timeout);
985 int woken_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
986 int autoremove_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
987 int wake_bit_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
988
989 #define DEFINE_WAIT_FUNC(name, function) \
990 wait_queue_t name = { \
991 .private = current, \
992 .func = function, \
993 .task_list = LIST_HEAD_INIT((name).task_list), \
994 }
995
996 #define DEFINE_WAIT(name) DEFINE_WAIT_FUNC(name, autoremove_wake_function)
997
998 #define DEFINE_WAIT_BIT(name, word, bit) \
999 struct wait_bit_queue name = { \
1000 .key = __WAIT_BIT_KEY_INITIALIZER(word, bit), \
1001 .wait = { \
1002 .private = current, \
1003 .func = wake_bit_function, \
1004 .task_list = \
1005 LIST_HEAD_INIT((name).wait.task_list), \
1006 }, \
1007 }
1008
1009 #define init_wait(wait) \
1010 do { \
1011 (wait)->private = current; \
1012 (wait)->func = autoremove_wake_function; \
1013 INIT_LIST_HEAD(&(wait)->task_list); \
1014 (wait)->flags = 0; \
1015 } while (0)
1016
1017
1018 extern int bit_wait(struct wait_bit_key *, int);
1019 extern int bit_wait_io(struct wait_bit_key *, int);
1020 extern int bit_wait_timeout(struct wait_bit_key *, int);
1021 extern int bit_wait_io_timeout(struct wait_bit_key *, int);
1022
1023 /**
1024 * wait_on_bit - wait for a bit to be cleared
1025 * @word: the word being waited on, a kernel virtual address
1026 * @bit: the bit of the word being waited on
1027 * @mode: the task state to sleep in
1028 *
1029 * There is a standard hashed waitqueue table for generic use. This
1030 * is the part of the hashtable's accessor API that waits on a bit.
1031 * For instance, if one were to have waiters on a bitflag, one would
1032 * call wait_on_bit() in threads waiting for the bit to clear.
1033 * One uses wait_on_bit() where one is waiting for the bit to clear,
1034 * but has no intention of setting it.
1035 * Returned value will be zero if the bit was cleared, or non-zero
1036 * if the process received a signal and the mode permitted wakeup
1037 * on that signal.
1038 */
1039 static inline int
wait_on_bit(unsigned long * word,int bit,unsigned mode)1040 wait_on_bit(unsigned long *word, int bit, unsigned mode)
1041 {
1042 might_sleep();
1043 if (!test_bit(bit, word))
1044 return 0;
1045 return out_of_line_wait_on_bit(word, bit,
1046 bit_wait,
1047 mode);
1048 }
1049
1050 /**
1051 * wait_on_bit_io - wait for a bit to be cleared
1052 * @word: the word being waited on, a kernel virtual address
1053 * @bit: the bit of the word being waited on
1054 * @mode: the task state to sleep in
1055 *
1056 * Use the standard hashed waitqueue table to wait for a bit
1057 * to be cleared. This is similar to wait_on_bit(), but calls
1058 * io_schedule() instead of schedule() for the actual waiting.
1059 *
1060 * Returned value will be zero if the bit was cleared, or non-zero
1061 * if the process received a signal and the mode permitted wakeup
1062 * on that signal.
1063 */
1064 static inline int
wait_on_bit_io(unsigned long * word,int bit,unsigned mode)1065 wait_on_bit_io(unsigned long *word, int bit, unsigned mode)
1066 {
1067 might_sleep();
1068 if (!test_bit(bit, word))
1069 return 0;
1070 return out_of_line_wait_on_bit(word, bit,
1071 bit_wait_io,
1072 mode);
1073 }
1074
1075 /**
1076 * wait_on_bit_timeout - wait for a bit to be cleared or a timeout elapses
1077 * @word: the word being waited on, a kernel virtual address
1078 * @bit: the bit of the word being waited on
1079 * @mode: the task state to sleep in
1080 * @timeout: timeout, in jiffies
1081 *
1082 * Use the standard hashed waitqueue table to wait for a bit
1083 * to be cleared. This is similar to wait_on_bit(), except also takes a
1084 * timeout parameter.
1085 *
1086 * Returned value will be zero if the bit was cleared before the
1087 * @timeout elapsed, or non-zero if the @timeout elapsed or process
1088 * received a signal and the mode permitted wakeup on that signal.
1089 */
1090 static inline int
wait_on_bit_timeout(unsigned long * word,int bit,unsigned mode,unsigned long timeout)1091 wait_on_bit_timeout(unsigned long *word, int bit, unsigned mode,
1092 unsigned long timeout)
1093 {
1094 might_sleep();
1095 if (!test_bit(bit, word))
1096 return 0;
1097 return out_of_line_wait_on_bit_timeout(word, bit,
1098 bit_wait_timeout,
1099 mode, timeout);
1100 }
1101
1102 /**
1103 * wait_on_bit_action - wait for a bit to be cleared
1104 * @word: the word being waited on, a kernel virtual address
1105 * @bit: the bit of the word being waited on
1106 * @action: the function used to sleep, which may take special actions
1107 * @mode: the task state to sleep in
1108 *
1109 * Use the standard hashed waitqueue table to wait for a bit
1110 * to be cleared, and allow the waiting action to be specified.
1111 * This is like wait_on_bit() but allows fine control of how the waiting
1112 * is done.
1113 *
1114 * Returned value will be zero if the bit was cleared, or non-zero
1115 * if the process received a signal and the mode permitted wakeup
1116 * on that signal.
1117 */
1118 static inline int
wait_on_bit_action(unsigned long * word,int bit,wait_bit_action_f * action,unsigned mode)1119 wait_on_bit_action(unsigned long *word, int bit, wait_bit_action_f *action,
1120 unsigned mode)
1121 {
1122 might_sleep();
1123 if (!test_bit(bit, word))
1124 return 0;
1125 return out_of_line_wait_on_bit(word, bit, action, mode);
1126 }
1127
1128 /**
1129 * wait_on_bit_lock - wait for a bit to be cleared, when wanting to set it
1130 * @word: the word being waited on, a kernel virtual address
1131 * @bit: the bit of the word being waited on
1132 * @mode: the task state to sleep in
1133 *
1134 * There is a standard hashed waitqueue table for generic use. This
1135 * is the part of the hashtable's accessor API that waits on a bit
1136 * when one intends to set it, for instance, trying to lock bitflags.
1137 * For instance, if one were to have waiters trying to set bitflag
1138 * and waiting for it to clear before setting it, one would call
1139 * wait_on_bit() in threads waiting to be able to set the bit.
1140 * One uses wait_on_bit_lock() where one is waiting for the bit to
1141 * clear with the intention of setting it, and when done, clearing it.
1142 *
1143 * Returns zero if the bit was (eventually) found to be clear and was
1144 * set. Returns non-zero if a signal was delivered to the process and
1145 * the @mode allows that signal to wake the process.
1146 */
1147 static inline int
wait_on_bit_lock(unsigned long * word,int bit,unsigned mode)1148 wait_on_bit_lock(unsigned long *word, int bit, unsigned mode)
1149 {
1150 might_sleep();
1151 if (!test_and_set_bit(bit, word))
1152 return 0;
1153 return out_of_line_wait_on_bit_lock(word, bit, bit_wait, mode);
1154 }
1155
1156 /**
1157 * wait_on_bit_lock_io - wait for a bit to be cleared, when wanting to set it
1158 * @word: the word being waited on, a kernel virtual address
1159 * @bit: the bit of the word being waited on
1160 * @mode: the task state to sleep in
1161 *
1162 * Use the standard hashed waitqueue table to wait for a bit
1163 * to be cleared and then to atomically set it. This is similar
1164 * to wait_on_bit(), but calls io_schedule() instead of schedule()
1165 * for the actual waiting.
1166 *
1167 * Returns zero if the bit was (eventually) found to be clear and was
1168 * set. Returns non-zero if a signal was delivered to the process and
1169 * the @mode allows that signal to wake the process.
1170 */
1171 static inline int
wait_on_bit_lock_io(unsigned long * word,int bit,unsigned mode)1172 wait_on_bit_lock_io(unsigned long *word, int bit, unsigned mode)
1173 {
1174 might_sleep();
1175 if (!test_and_set_bit(bit, word))
1176 return 0;
1177 return out_of_line_wait_on_bit_lock(word, bit, bit_wait_io, mode);
1178 }
1179
1180 /**
1181 * wait_on_bit_lock_action - wait for a bit to be cleared, when wanting to set it
1182 * @word: the word being waited on, a kernel virtual address
1183 * @bit: the bit of the word being waited on
1184 * @action: the function used to sleep, which may take special actions
1185 * @mode: the task state to sleep in
1186 *
1187 * Use the standard hashed waitqueue table to wait for a bit
1188 * to be cleared and then to set it, and allow the waiting action
1189 * to be specified.
1190 * This is like wait_on_bit() but allows fine control of how the waiting
1191 * is done.
1192 *
1193 * Returns zero if the bit was (eventually) found to be clear and was
1194 * set. Returns non-zero if a signal was delivered to the process and
1195 * the @mode allows that signal to wake the process.
1196 */
1197 static inline int
wait_on_bit_lock_action(unsigned long * word,int bit,wait_bit_action_f * action,unsigned mode)1198 wait_on_bit_lock_action(unsigned long *word, int bit, wait_bit_action_f *action,
1199 unsigned mode)
1200 {
1201 might_sleep();
1202 if (!test_and_set_bit(bit, word))
1203 return 0;
1204 return out_of_line_wait_on_bit_lock(word, bit, action, mode);
1205 }
1206
1207 /**
1208 * wait_on_atomic_t - Wait for an atomic_t to become 0
1209 * @val: The atomic value being waited on, a kernel virtual address
1210 * @action: the function used to sleep, which may take special actions
1211 * @mode: the task state to sleep in
1212 *
1213 * Wait for an atomic_t to become 0. We abuse the bit-wait waitqueue table for
1214 * the purpose of getting a waitqueue, but we set the key to a bit number
1215 * outside of the target 'word'.
1216 */
1217 static inline
wait_on_atomic_t(atomic_t * val,int (* action)(atomic_t *),unsigned mode)1218 int wait_on_atomic_t(atomic_t *val, int (*action)(atomic_t *), unsigned mode)
1219 {
1220 might_sleep();
1221 if (atomic_read(val) == 0)
1222 return 0;
1223 return out_of_line_wait_on_atomic_t(val, action, mode);
1224 }
1225
1226 #endif /* _LINUX_WAIT_H */
1227