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Linux/include/linux/wait.h

  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 
 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
 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  */
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  */
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 
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
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 
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
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
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 /*
252  * The below macro ___wait_event() has an explicit shadow of the __ret
253  * variable when used from the wait_event_*() macros.
254  *
255  * This is so that both can use the ___wait_cond_timeout() construct
256  * to wrap the condition.
257  *
258  * The type inconsistency of the wait_event_*() __ret variable is also
259  * on purpose; we use long where we can return timeout values and int
260  * otherwise.
261  */
262 
263 #define ___wait_event(wq, condition, state, exclusive, ret, cmd)        \
264 ({                                                                      \
265         __label__ __out;                                                \
266         wait_queue_t __wait;                                            \
267         long __ret = ret;       /* explicit shadow */                   \
268                                                                         \
269         INIT_LIST_HEAD(&__wait.task_list);                              \
270         if (exclusive)                                                  \
271                 __wait.flags = WQ_FLAG_EXCLUSIVE;                       \
272         else                                                            \
273                 __wait.flags = 0;                                       \
274                                                                         \
275         for (;;) {                                                      \
276                 long __int = prepare_to_wait_event(&wq, &__wait, state);\
277                                                                         \
278                 if (condition)                                          \
279                         break;                                          \
280                                                                         \
281                 if (___wait_is_interruptible(state) && __int) {         \
282                         __ret = __int;                                  \
283                         if (exclusive) {                                \
284                                 abort_exclusive_wait(&wq, &__wait,      \
285                                                      state, NULL);      \
286                                 goto __out;                             \
287                         }                                               \
288                         break;                                          \
289                 }                                                       \
290                                                                         \
291                 cmd;                                                    \
292         }                                                               \
293         finish_wait(&wq, &__wait);                                      \
294 __out:  __ret;                                                          \
295 })
296 
297 #define __wait_event(wq, condition)                                     \
298         (void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0, 0,  \
299                             schedule())
300 
301 /**
302  * wait_event - sleep until a condition gets true
303  * @wq: the waitqueue to wait on
304  * @condition: a C expression for the event to wait for
305  *
306  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
307  * @condition evaluates to true. The @condition is checked each time
308  * the waitqueue @wq is woken up.
309  *
310  * wake_up() has to be called after changing any variable that could
311  * change the result of the wait condition.
312  */
313 #define wait_event(wq, condition)                                       \
314 do {                                                                    \
315         might_sleep();                                                  \
316         if (condition)                                                  \
317                 break;                                                  \
318         __wait_event(wq, condition);                                    \
319 } while (0)
320 
321 #define __io_wait_event(wq, condition)                                  \
322         (void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0, 0,  \
323                             io_schedule())
324 
325 /*
326  * io_wait_event() -- like wait_event() but with io_schedule()
327  */
328 #define io_wait_event(wq, condition)                                    \
329 do {                                                                    \
330         might_sleep();                                                  \
331         if (condition)                                                  \
332                 break;                                                  \
333         __io_wait_event(wq, condition);                                 \
334 } while (0)
335 
336 #define __wait_event_freezable(wq, condition)                           \
337         ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 0, 0,          \
338                             schedule(); try_to_freeze())
339 
340 /**
341  * wait_event_freezable - sleep (or freeze) until a condition gets true
342  * @wq: the waitqueue to wait on
343  * @condition: a C expression for the event to wait for
344  *
345  * The process is put to sleep (TASK_INTERRUPTIBLE -- so as not to contribute
346  * to system load) until the @condition evaluates to true. The
347  * @condition is checked each time the waitqueue @wq is woken up.
348  *
349  * wake_up() has to be called after changing any variable that could
350  * change the result of the wait condition.
351  */
352 #define wait_event_freezable(wq, condition)                             \
353 ({                                                                      \
354         int __ret = 0;                                                  \
355         might_sleep();                                                  \
356         if (!(condition))                                               \
357                 __ret = __wait_event_freezable(wq, condition);          \
358         __ret;                                                          \
359 })
360 
361 #define __wait_event_timeout(wq, condition, timeout)                    \
362         ___wait_event(wq, ___wait_cond_timeout(condition),              \
363                       TASK_UNINTERRUPTIBLE, 0, timeout,                 \
364                       __ret = schedule_timeout(__ret))
365 
366 /**
367  * wait_event_timeout - sleep until a condition gets true or a timeout elapses
368  * @wq: the waitqueue to wait on
369  * @condition: a C expression for the event to wait for
370  * @timeout: timeout, in jiffies
371  *
372  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
373  * @condition evaluates to true. The @condition is checked each time
374  * the waitqueue @wq is woken up.
375  *
376  * wake_up() has to be called after changing any variable that could
377  * change the result of the wait condition.
378  *
379  * Returns:
380  * 0 if the @condition evaluated to %false after the @timeout elapsed,
381  * 1 if the @condition evaluated to %true after the @timeout elapsed,
382  * or the remaining jiffies (at least 1) if the @condition evaluated
383  * to %true before the @timeout elapsed.
384  */
385 #define wait_event_timeout(wq, condition, timeout)                      \
386 ({                                                                      \
387         long __ret = timeout;                                           \
388         might_sleep();                                                  \
389         if (!___wait_cond_timeout(condition))                           \
390                 __ret = __wait_event_timeout(wq, condition, timeout);   \
391         __ret;                                                          \
392 })
393 
394 #define __wait_event_freezable_timeout(wq, condition, timeout)          \
395         ___wait_event(wq, ___wait_cond_timeout(condition),              \
396                       TASK_INTERRUPTIBLE, 0, timeout,                   \
397                       __ret = schedule_timeout(__ret); try_to_freeze())
398 
399 /*
400  * like wait_event_timeout() -- except it uses TASK_INTERRUPTIBLE to avoid
401  * increasing load and is freezable.
402  */
403 #define wait_event_freezable_timeout(wq, condition, timeout)            \
404 ({                                                                      \
405         long __ret = timeout;                                           \
406         might_sleep();                                                  \
407         if (!___wait_cond_timeout(condition))                           \
408                 __ret = __wait_event_freezable_timeout(wq, condition, timeout); \
409         __ret;                                                          \
410 })
411 
412 #define __wait_event_exclusive_cmd(wq, condition, cmd1, cmd2)           \
413         (void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 1, 0,  \
414                             cmd1; schedule(); cmd2)
415 /*
416  * Just like wait_event_cmd(), except it sets exclusive flag
417  */
418 #define wait_event_exclusive_cmd(wq, condition, cmd1, cmd2)             \
419 do {                                                                    \
420         if (condition)                                                  \
421                 break;                                                  \
422         __wait_event_exclusive_cmd(wq, condition, cmd1, cmd2);          \
423 } while (0)
424 
425 #define __wait_event_cmd(wq, condition, cmd1, cmd2)                     \
426         (void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0, 0,  \
427                             cmd1; schedule(); cmd2)
428 
429 /**
430  * wait_event_cmd - sleep until a condition gets true
431  * @wq: the waitqueue to wait on
432  * @condition: a C expression for the event to wait for
433  * @cmd1: the command will be executed before sleep
434  * @cmd2: the command will be executed after sleep
435  *
436  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
437  * @condition evaluates to true. The @condition is checked each time
438  * the waitqueue @wq is woken up.
439  *
440  * wake_up() has to be called after changing any variable that could
441  * change the result of the wait condition.
442  */
443 #define wait_event_cmd(wq, condition, cmd1, cmd2)                       \
444 do {                                                                    \
445         if (condition)                                                  \
446                 break;                                                  \
447         __wait_event_cmd(wq, condition, cmd1, cmd2);                    \
448 } while (0)
449 
450 #define __wait_event_interruptible(wq, condition)                       \
451         ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 0, 0,          \
452                       schedule())
453 
454 /**
455  * wait_event_interruptible - sleep until a condition gets true
456  * @wq: the waitqueue to wait on
457  * @condition: a C expression for the event to wait for
458  *
459  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
460  * @condition evaluates to true or a signal is received.
461  * The @condition is checked each time the waitqueue @wq is woken up.
462  *
463  * wake_up() has to be called after changing any variable that could
464  * change the result of the wait condition.
465  *
466  * The function will return -ERESTARTSYS if it was interrupted by a
467  * signal and 0 if @condition evaluated to true.
468  */
469 #define wait_event_interruptible(wq, condition)                         \
470 ({                                                                      \
471         int __ret = 0;                                                  \
472         might_sleep();                                                  \
473         if (!(condition))                                               \
474                 __ret = __wait_event_interruptible(wq, condition);      \
475         __ret;                                                          \
476 })
477 
478 #define __wait_event_interruptible_timeout(wq, condition, timeout)      \
479         ___wait_event(wq, ___wait_cond_timeout(condition),              \
480                       TASK_INTERRUPTIBLE, 0, timeout,                   \
481                       __ret = schedule_timeout(__ret))
482 
483 /**
484  * wait_event_interruptible_timeout - sleep until a condition gets true or a timeout elapses
485  * @wq: the waitqueue to wait on
486  * @condition: a C expression for the event to wait for
487  * @timeout: timeout, in jiffies
488  *
489  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
490  * @condition evaluates to true or a signal is received.
491  * The @condition is checked each time the waitqueue @wq is woken up.
492  *
493  * wake_up() has to be called after changing any variable that could
494  * change the result of the wait condition.
495  *
496  * Returns:
497  * 0 if the @condition evaluated to %false after the @timeout elapsed,
498  * 1 if the @condition evaluated to %true after the @timeout elapsed,
499  * the remaining jiffies (at least 1) if the @condition evaluated
500  * to %true before the @timeout elapsed, or -%ERESTARTSYS if it was
501  * interrupted by a signal.
502  */
503 #define wait_event_interruptible_timeout(wq, condition, timeout)        \
504 ({                                                                      \
505         long __ret = timeout;                                           \
506         might_sleep();                                                  \
507         if (!___wait_cond_timeout(condition))                           \
508                 __ret = __wait_event_interruptible_timeout(wq,          \
509                                                 condition, timeout);    \
510         __ret;                                                          \
511 })
512 
513 #define __wait_event_hrtimeout(wq, condition, timeout, state)           \
514 ({                                                                      \
515         int __ret = 0;                                                  \
516         struct hrtimer_sleeper __t;                                     \
517                                                                         \
518         hrtimer_init_on_stack(&__t.timer, CLOCK_MONOTONIC,              \
519                               HRTIMER_MODE_REL);                        \
520         hrtimer_init_sleeper(&__t, current);                            \
521         if ((timeout).tv64 != KTIME_MAX)                                \
522                 hrtimer_start_range_ns(&__t.timer, timeout,             \
523                                        current->timer_slack_ns,         \
524                                        HRTIMER_MODE_REL);               \
525                                                                         \
526         __ret = ___wait_event(wq, condition, state, 0, 0,               \
527                 if (!__t.task) {                                        \
528                         __ret = -ETIME;                                 \
529                         break;                                          \
530                 }                                                       \
531                 schedule());                                            \
532                                                                         \
533         hrtimer_cancel(&__t.timer);                                     \
534         destroy_hrtimer_on_stack(&__t.timer);                           \
535         __ret;                                                          \
536 })
537 
538 /**
539  * wait_event_hrtimeout - sleep until a condition gets true or a timeout elapses
540  * @wq: the waitqueue to wait on
541  * @condition: a C expression for the event to wait for
542  * @timeout: timeout, as a ktime_t
543  *
544  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
545  * @condition evaluates to true or a signal is received.
546  * The @condition is checked each time the waitqueue @wq is woken up.
547  *
548  * wake_up() has to be called after changing any variable that could
549  * change the result of the wait condition.
550  *
551  * The function returns 0 if @condition became true, or -ETIME if the timeout
552  * elapsed.
553  */
554 #define wait_event_hrtimeout(wq, condition, timeout)                    \
555 ({                                                                      \
556         int __ret = 0;                                                  \
557         might_sleep();                                                  \
558         if (!(condition))                                               \
559                 __ret = __wait_event_hrtimeout(wq, condition, timeout,  \
560                                                TASK_UNINTERRUPTIBLE);   \
561         __ret;                                                          \
562 })
563 
564 /**
565  * wait_event_interruptible_hrtimeout - sleep until a condition gets true or a timeout elapses
566  * @wq: the waitqueue to wait on
567  * @condition: a C expression for the event to wait for
568  * @timeout: timeout, as a ktime_t
569  *
570  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
571  * @condition evaluates to true or a signal is received.
572  * The @condition is checked each time the waitqueue @wq is woken up.
573  *
574  * wake_up() has to be called after changing any variable that could
575  * change the result of the wait condition.
576  *
577  * The function returns 0 if @condition became true, -ERESTARTSYS if it was
578  * interrupted by a signal, or -ETIME if the timeout elapsed.
579  */
580 #define wait_event_interruptible_hrtimeout(wq, condition, timeout)      \
581 ({                                                                      \
582         long __ret = 0;                                                 \
583         might_sleep();                                                  \
584         if (!(condition))                                               \
585                 __ret = __wait_event_hrtimeout(wq, condition, timeout,  \
586                                                TASK_INTERRUPTIBLE);     \
587         __ret;                                                          \
588 })
589 
590 #define __wait_event_interruptible_exclusive(wq, condition)             \
591         ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 1, 0,          \
592                       schedule())
593 
594 #define wait_event_interruptible_exclusive(wq, condition)               \
595 ({                                                                      \
596         int __ret = 0;                                                  \
597         might_sleep();                                                  \
598         if (!(condition))                                               \
599                 __ret = __wait_event_interruptible_exclusive(wq, condition);\
600         __ret;                                                          \
601 })
602 
603 
604 #define __wait_event_freezable_exclusive(wq, condition)                 \
605         ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 1, 0,          \
606                         schedule(); try_to_freeze())
607 
608 #define wait_event_freezable_exclusive(wq, condition)                   \
609 ({                                                                      \
610         int __ret = 0;                                                  \
611         might_sleep();                                                  \
612         if (!(condition))                                               \
613                 __ret = __wait_event_freezable_exclusive(wq, condition);\
614         __ret;                                                          \
615 })
616 
617 
618 #define __wait_event_interruptible_locked(wq, condition, exclusive, irq) \
619 ({                                                                      \
620         int __ret = 0;                                                  \
621         DEFINE_WAIT(__wait);                                            \
622         if (exclusive)                                                  \
623                 __wait.flags |= WQ_FLAG_EXCLUSIVE;                      \
624         do {                                                            \
625                 if (likely(list_empty(&__wait.task_list)))              \
626                         __add_wait_queue_tail(&(wq), &__wait);          \
627                 set_current_state(TASK_INTERRUPTIBLE);                  \
628                 if (signal_pending(current)) {                          \
629                         __ret = -ERESTARTSYS;                           \
630                         break;                                          \
631                 }                                                       \
632                 if (irq)                                                \
633                         spin_unlock_irq(&(wq).lock);                    \
634                 else                                                    \
635                         spin_unlock(&(wq).lock);                        \
636                 schedule();                                             \
637                 if (irq)                                                \
638                         spin_lock_irq(&(wq).lock);                      \
639                 else                                                    \
640                         spin_lock(&(wq).lock);                          \
641         } while (!(condition));                                         \
642         __remove_wait_queue(&(wq), &__wait);                            \
643         __set_current_state(TASK_RUNNING);                              \
644         __ret;                                                          \
645 })
646 
647 
648 /**
649  * wait_event_interruptible_locked - sleep until a condition gets true
650  * @wq: the waitqueue to wait on
651  * @condition: a C expression for the event to wait for
652  *
653  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
654  * @condition evaluates to true or a signal is received.
655  * The @condition is checked each time the waitqueue @wq is woken up.
656  *
657  * It must be called with wq.lock being held.  This spinlock is
658  * unlocked while sleeping but @condition testing is done while lock
659  * is held and when this macro exits the lock is held.
660  *
661  * The lock is locked/unlocked using spin_lock()/spin_unlock()
662  * functions which must match the way they are locked/unlocked outside
663  * of this macro.
664  *
665  * wake_up_locked() has to be called after changing any variable that could
666  * change the result of the wait condition.
667  *
668  * The function will return -ERESTARTSYS if it was interrupted by a
669  * signal and 0 if @condition evaluated to true.
670  */
671 #define wait_event_interruptible_locked(wq, condition)                  \
672         ((condition)                                                    \
673          ? 0 : __wait_event_interruptible_locked(wq, condition, 0, 0))
674 
675 /**
676  * wait_event_interruptible_locked_irq - sleep until a condition gets true
677  * @wq: the waitqueue to wait on
678  * @condition: a C expression for the event to wait for
679  *
680  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
681  * @condition evaluates to true or a signal is received.
682  * The @condition is checked each time the waitqueue @wq is woken up.
683  *
684  * It must be called with wq.lock being held.  This spinlock is
685  * unlocked while sleeping but @condition testing is done while lock
686  * is held and when this macro exits the lock is held.
687  *
688  * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq()
689  * functions which must match the way they are locked/unlocked outside
690  * of this macro.
691  *
692  * wake_up_locked() has to be called after changing any variable that could
693  * change the result of the wait condition.
694  *
695  * The function will return -ERESTARTSYS if it was interrupted by a
696  * signal and 0 if @condition evaluated to true.
697  */
698 #define wait_event_interruptible_locked_irq(wq, condition)              \
699         ((condition)                                                    \
700          ? 0 : __wait_event_interruptible_locked(wq, condition, 0, 1))
701 
702 /**
703  * wait_event_interruptible_exclusive_locked - sleep exclusively until a condition gets true
704  * @wq: the waitqueue to wait on
705  * @condition: a C expression for the event to wait for
706  *
707  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
708  * @condition evaluates to true or a signal is received.
709  * The @condition is checked each time the waitqueue @wq is woken up.
710  *
711  * It must be called with wq.lock being held.  This spinlock is
712  * unlocked while sleeping but @condition testing is done while lock
713  * is held and when this macro exits the lock is held.
714  *
715  * The lock is locked/unlocked using spin_lock()/spin_unlock()
716  * functions which must match the way they are locked/unlocked outside
717  * of this macro.
718  *
719  * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
720  * set thus when other process waits process on the list if this
721  * process is awaken further processes are not considered.
722  *
723  * wake_up_locked() has to be called after changing any variable that could
724  * change the result of the wait condition.
725  *
726  * The function will return -ERESTARTSYS if it was interrupted by a
727  * signal and 0 if @condition evaluated to true.
728  */
729 #define wait_event_interruptible_exclusive_locked(wq, condition)        \
730         ((condition)                                                    \
731          ? 0 : __wait_event_interruptible_locked(wq, condition, 1, 0))
732 
733 /**
734  * wait_event_interruptible_exclusive_locked_irq - sleep until a condition gets true
735  * @wq: the waitqueue to wait on
736  * @condition: a C expression for the event to wait for
737  *
738  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
739  * @condition evaluates to true or a signal is received.
740  * The @condition is checked each time the waitqueue @wq is woken up.
741  *
742  * It must be called with wq.lock being held.  This spinlock is
743  * unlocked while sleeping but @condition testing is done while lock
744  * is held and when this macro exits the lock is held.
745  *
746  * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq()
747  * functions which must match the way they are locked/unlocked outside
748  * of this macro.
749  *
750  * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
751  * set thus when other process waits process on the list if this
752  * process is awaken further processes are not considered.
753  *
754  * wake_up_locked() has to be called after changing any variable that could
755  * change the result of the wait condition.
756  *
757  * The function will return -ERESTARTSYS if it was interrupted by a
758  * signal and 0 if @condition evaluated to true.
759  */
760 #define wait_event_interruptible_exclusive_locked_irq(wq, condition)    \
761         ((condition)                                                    \
762          ? 0 : __wait_event_interruptible_locked(wq, condition, 1, 1))
763 
764 
765 #define __wait_event_killable(wq, condition)                            \
766         ___wait_event(wq, condition, TASK_KILLABLE, 0, 0, schedule())
767 
768 /**
769  * wait_event_killable - sleep until a condition gets true
770  * @wq: the waitqueue to wait on
771  * @condition: a C expression for the event to wait for
772  *
773  * The process is put to sleep (TASK_KILLABLE) until the
774  * @condition evaluates to true or a signal is received.
775  * The @condition is checked each time the waitqueue @wq is woken up.
776  *
777  * wake_up() has to be called after changing any variable that could
778  * change the result of the wait condition.
779  *
780  * The function will return -ERESTARTSYS if it was interrupted by a
781  * signal and 0 if @condition evaluated to true.
782  */
783 #define wait_event_killable(wq, condition)                              \
784 ({                                                                      \
785         int __ret = 0;                                                  \
786         might_sleep();                                                  \
787         if (!(condition))                                               \
788                 __ret = __wait_event_killable(wq, condition);           \
789         __ret;                                                          \
790 })
791 
792 
793 #define __wait_event_lock_irq(wq, condition, lock, cmd)                 \
794         (void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0, 0,  \
795                             spin_unlock_irq(&lock);                     \
796                             cmd;                                        \
797                             schedule();                                 \
798                             spin_lock_irq(&lock))
799 
800 /**
801  * wait_event_lock_irq_cmd - sleep until a condition gets true. The
802  *                           condition is checked under the lock. This
803  *                           is expected to be called with the lock
804  *                           taken.
805  * @wq: the waitqueue to wait on
806  * @condition: a C expression for the event to wait for
807  * @lock: a locked spinlock_t, which will be released before cmd
808  *        and schedule() and reacquired afterwards.
809  * @cmd: a command which is invoked outside the critical section before
810  *       sleep
811  *
812  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
813  * @condition evaluates to true. The @condition is checked each time
814  * the waitqueue @wq is woken up.
815  *
816  * wake_up() has to be called after changing any variable that could
817  * change the result of the wait condition.
818  *
819  * This is supposed to be called while holding the lock. The lock is
820  * dropped before invoking the cmd and going to sleep and is reacquired
821  * afterwards.
822  */
823 #define wait_event_lock_irq_cmd(wq, condition, lock, cmd)               \
824 do {                                                                    \
825         if (condition)                                                  \
826                 break;                                                  \
827         __wait_event_lock_irq(wq, condition, lock, cmd);                \
828 } while (0)
829 
830 /**
831  * wait_event_lock_irq - sleep until a condition gets true. The
832  *                       condition is checked under the lock. This
833  *                       is expected to be called with the lock
834  *                       taken.
835  * @wq: the waitqueue to wait on
836  * @condition: a C expression for the event to wait for
837  * @lock: a locked spinlock_t, which will be released before schedule()
838  *        and reacquired afterwards.
839  *
840  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
841  * @condition evaluates to true. The @condition is checked each time
842  * the waitqueue @wq is woken up.
843  *
844  * wake_up() has to be called after changing any variable that could
845  * change the result of the wait condition.
846  *
847  * This is supposed to be called while holding the lock. The lock is
848  * dropped before going to sleep and is reacquired afterwards.
849  */
850 #define wait_event_lock_irq(wq, condition, lock)                        \
851 do {                                                                    \
852         if (condition)                                                  \
853                 break;                                                  \
854         __wait_event_lock_irq(wq, condition, lock, );                   \
855 } while (0)
856 
857 
858 #define __wait_event_interruptible_lock_irq(wq, condition, lock, cmd)   \
859         ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 0, 0,          \
860                       spin_unlock_irq(&lock);                           \
861                       cmd;                                              \
862                       schedule();                                       \
863                       spin_lock_irq(&lock))
864 
865 /**
866  * wait_event_interruptible_lock_irq_cmd - sleep until a condition gets true.
867  *              The condition is checked under the lock. This is expected to
868  *              be called with the lock taken.
869  * @wq: the waitqueue to wait on
870  * @condition: a C expression for the event to wait for
871  * @lock: a locked spinlock_t, which will be released before cmd and
872  *        schedule() and reacquired afterwards.
873  * @cmd: a command which is invoked outside the critical section before
874  *       sleep
875  *
876  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
877  * @condition evaluates to true or a signal is received. The @condition is
878  * checked each time the waitqueue @wq is woken up.
879  *
880  * wake_up() has to be called after changing any variable that could
881  * change the result of the wait condition.
882  *
883  * This is supposed to be called while holding the lock. The lock is
884  * dropped before invoking the cmd and going to sleep and is reacquired
885  * afterwards.
886  *
887  * The macro will return -ERESTARTSYS if it was interrupted by a signal
888  * and 0 if @condition evaluated to true.
889  */
890 #define wait_event_interruptible_lock_irq_cmd(wq, condition, lock, cmd) \
891 ({                                                                      \
892         int __ret = 0;                                                  \
893         if (!(condition))                                               \
894                 __ret = __wait_event_interruptible_lock_irq(wq,         \
895                                                 condition, lock, cmd);  \
896         __ret;                                                          \
897 })
898 
899 /**
900  * wait_event_interruptible_lock_irq - sleep until a condition gets true.
901  *              The condition is checked under the lock. This is expected
902  *              to be called with the lock taken.
903  * @wq: the waitqueue to wait on
904  * @condition: a C expression for the event to wait for
905  * @lock: a locked spinlock_t, which will be released before schedule()
906  *        and reacquired afterwards.
907  *
908  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
909  * @condition evaluates to true or signal is received. The @condition is
910  * checked each time the waitqueue @wq is woken up.
911  *
912  * wake_up() has to be called after changing any variable that could
913  * change the result of the wait condition.
914  *
915  * This is supposed to be called while holding the lock. The lock is
916  * dropped before going to sleep and is reacquired afterwards.
917  *
918  * The macro will return -ERESTARTSYS if it was interrupted by a signal
919  * and 0 if @condition evaluated to true.
920  */
921 #define wait_event_interruptible_lock_irq(wq, condition, lock)          \
922 ({                                                                      \
923         int __ret = 0;                                                  \
924         if (!(condition))                                               \
925                 __ret = __wait_event_interruptible_lock_irq(wq,         \
926                                                 condition, lock,);      \
927         __ret;                                                          \
928 })
929 
930 #define __wait_event_interruptible_lock_irq_timeout(wq, condition,      \
931                                                     lock, timeout)      \
932         ___wait_event(wq, ___wait_cond_timeout(condition),              \
933                       TASK_INTERRUPTIBLE, 0, timeout,                   \
934                       spin_unlock_irq(&lock);                           \
935                       __ret = schedule_timeout(__ret);                  \
936                       spin_lock_irq(&lock));
937 
938 /**
939  * wait_event_interruptible_lock_irq_timeout - sleep until a condition gets
940  *              true or a timeout elapses. The condition is checked under
941  *              the lock. This is expected to be called with the lock taken.
942  * @wq: the waitqueue to wait on
943  * @condition: a C expression for the event to wait for
944  * @lock: a locked spinlock_t, which will be released before schedule()
945  *        and reacquired afterwards.
946  * @timeout: timeout, in jiffies
947  *
948  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
949  * @condition evaluates to true or signal is received. The @condition is
950  * checked each time the waitqueue @wq is woken up.
951  *
952  * wake_up() has to be called after changing any variable that could
953  * change the result of the wait condition.
954  *
955  * This is supposed to be called while holding the lock. The lock is
956  * dropped before going to sleep and is reacquired afterwards.
957  *
958  * The function returns 0 if the @timeout elapsed, -ERESTARTSYS if it
959  * was interrupted by a signal, and the remaining jiffies otherwise
960  * if the condition evaluated to true before the timeout elapsed.
961  */
962 #define wait_event_interruptible_lock_irq_timeout(wq, condition, lock,  \
963                                                   timeout)              \
964 ({                                                                      \
965         long __ret = timeout;                                           \
966         if (!___wait_cond_timeout(condition))                           \
967                 __ret = __wait_event_interruptible_lock_irq_timeout(    \
968                                         wq, condition, lock, timeout);  \
969         __ret;                                                          \
970 })
971 
972 /*
973  * Waitqueues which are removed from the waitqueue_head at wakeup time
974  */
975 void prepare_to_wait(wait_queue_head_t *q, wait_queue_t *wait, int state);
976 void prepare_to_wait_exclusive(wait_queue_head_t *q, wait_queue_t *wait, int state);
977 long prepare_to_wait_event(wait_queue_head_t *q, wait_queue_t *wait, int state);
978 void finish_wait(wait_queue_head_t *q, wait_queue_t *wait);
979 void abort_exclusive_wait(wait_queue_head_t *q, wait_queue_t *wait, unsigned int mode, void *key);
980 long wait_woken(wait_queue_t *wait, unsigned mode, long timeout);
981 int woken_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
982 int autoremove_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
983 int wake_bit_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
984 
985 #define DEFINE_WAIT_FUNC(name, function)                                \
986         wait_queue_t name = {                                           \
987                 .private        = current,                              \
988                 .func           = function,                             \
989                 .task_list      = LIST_HEAD_INIT((name).task_list),     \
990         }
991 
992 #define DEFINE_WAIT(name) DEFINE_WAIT_FUNC(name, autoremove_wake_function)
993 
994 #define DEFINE_WAIT_BIT(name, word, bit)                                \
995         struct wait_bit_queue name = {                                  \
996                 .key = __WAIT_BIT_KEY_INITIALIZER(word, bit),           \
997                 .wait   = {                                             \
998                         .private        = current,                      \
999                         .func           = wake_bit_function,            \
1000                         .task_list      =                               \
1001                                 LIST_HEAD_INIT((name).wait.task_list),  \
1002                 },                                                      \
1003         }
1004 
1005 #define init_wait(wait)                                                 \
1006         do {                                                            \
1007                 (wait)->private = current;                              \
1008                 (wait)->func = autoremove_wake_function;                \
1009                 INIT_LIST_HEAD(&(wait)->task_list);                     \
1010                 (wait)->flags = 0;                                      \
1011         } while (0)
1012 
1013 
1014 extern int bit_wait(struct wait_bit_key *, int);
1015 extern int bit_wait_io(struct wait_bit_key *, int);
1016 extern int bit_wait_timeout(struct wait_bit_key *, int);
1017 extern int bit_wait_io_timeout(struct wait_bit_key *, int);
1018 
1019 /**
1020  * wait_on_bit - wait for a bit to be cleared
1021  * @word: the word being waited on, a kernel virtual address
1022  * @bit: the bit of the word being waited on
1023  * @mode: the task state to sleep in
1024  *
1025  * There is a standard hashed waitqueue table for generic use. This
1026  * is the part of the hashtable's accessor API that waits on a bit.
1027  * For instance, if one were to have waiters on a bitflag, one would
1028  * call wait_on_bit() in threads waiting for the bit to clear.
1029  * One uses wait_on_bit() where one is waiting for the bit to clear,
1030  * but has no intention of setting it.
1031  * Returned value will be zero if the bit was cleared, or non-zero
1032  * if the process received a signal and the mode permitted wakeup
1033  * on that signal.
1034  */
1035 static inline int
1036 wait_on_bit(unsigned long *word, int bit, unsigned mode)
1037 {
1038         might_sleep();
1039         if (!test_bit(bit, word))
1040                 return 0;
1041         return out_of_line_wait_on_bit(word, bit,
1042                                        bit_wait,
1043                                        mode);
1044 }
1045 
1046 /**
1047  * wait_on_bit_io - wait for a bit to be cleared
1048  * @word: the word being waited on, a kernel virtual address
1049  * @bit: the bit of the word being waited on
1050  * @mode: the task state to sleep in
1051  *
1052  * Use the standard hashed waitqueue table to wait for a bit
1053  * to be cleared.  This is similar to wait_on_bit(), but calls
1054  * io_schedule() instead of schedule() for the actual waiting.
1055  *
1056  * Returned value will be zero if the bit was cleared, or non-zero
1057  * if the process received a signal and the mode permitted wakeup
1058  * on that signal.
1059  */
1060 static inline int
1061 wait_on_bit_io(unsigned long *word, int bit, unsigned mode)
1062 {
1063         might_sleep();
1064         if (!test_bit(bit, word))
1065                 return 0;
1066         return out_of_line_wait_on_bit(word, bit,
1067                                        bit_wait_io,
1068                                        mode);
1069 }
1070 
1071 /**
1072  * wait_on_bit_timeout - wait for a bit to be cleared or a timeout elapses
1073  * @word: the word being waited on, a kernel virtual address
1074  * @bit: the bit of the word being waited on
1075  * @mode: the task state to sleep in
1076  * @timeout: timeout, in jiffies
1077  *
1078  * Use the standard hashed waitqueue table to wait for a bit
1079  * to be cleared. This is similar to wait_on_bit(), except also takes a
1080  * timeout parameter.
1081  *
1082  * Returned value will be zero if the bit was cleared before the
1083  * @timeout elapsed, or non-zero if the @timeout elapsed or process
1084  * received a signal and the mode permitted wakeup on that signal.
1085  */
1086 static inline int
1087 wait_on_bit_timeout(unsigned long *word, int bit, unsigned mode,
1088                     unsigned long timeout)
1089 {
1090         might_sleep();
1091         if (!test_bit(bit, word))
1092                 return 0;
1093         return out_of_line_wait_on_bit_timeout(word, bit,
1094                                                bit_wait_timeout,
1095                                                mode, timeout);
1096 }
1097 
1098 /**
1099  * wait_on_bit_action - wait for a bit to be cleared
1100  * @word: the word being waited on, a kernel virtual address
1101  * @bit: the bit of the word being waited on
1102  * @action: the function used to sleep, which may take special actions
1103  * @mode: the task state to sleep in
1104  *
1105  * Use the standard hashed waitqueue table to wait for a bit
1106  * to be cleared, and allow the waiting action to be specified.
1107  * This is like wait_on_bit() but allows fine control of how the waiting
1108  * is done.
1109  *
1110  * Returned value will be zero if the bit was cleared, or non-zero
1111  * if the process received a signal and the mode permitted wakeup
1112  * on that signal.
1113  */
1114 static inline int
1115 wait_on_bit_action(unsigned long *word, int bit, wait_bit_action_f *action,
1116                    unsigned mode)
1117 {
1118         might_sleep();
1119         if (!test_bit(bit, word))
1120                 return 0;
1121         return out_of_line_wait_on_bit(word, bit, action, mode);
1122 }
1123 
1124 /**
1125  * wait_on_bit_lock - wait for a bit to be cleared, when wanting to set it
1126  * @word: the word being waited on, a kernel virtual address
1127  * @bit: the bit of the word being waited on
1128  * @mode: the task state to sleep in
1129  *
1130  * There is a standard hashed waitqueue table for generic use. This
1131  * is the part of the hashtable's accessor API that waits on a bit
1132  * when one intends to set it, for instance, trying to lock bitflags.
1133  * For instance, if one were to have waiters trying to set bitflag
1134  * and waiting for it to clear before setting it, one would call
1135  * wait_on_bit() in threads waiting to be able to set the bit.
1136  * One uses wait_on_bit_lock() where one is waiting for the bit to
1137  * clear with the intention of setting it, and when done, clearing it.
1138  *
1139  * Returns zero if the bit was (eventually) found to be clear and was
1140  * set.  Returns non-zero if a signal was delivered to the process and
1141  * the @mode allows that signal to wake the process.
1142  */
1143 static inline int
1144 wait_on_bit_lock(unsigned long *word, int bit, unsigned mode)
1145 {
1146         might_sleep();
1147         if (!test_and_set_bit(bit, word))
1148                 return 0;
1149         return out_of_line_wait_on_bit_lock(word, bit, bit_wait, mode);
1150 }
1151 
1152 /**
1153  * wait_on_bit_lock_io - wait for a bit to be cleared, when wanting to set it
1154  * @word: the word being waited on, a kernel virtual address
1155  * @bit: the bit of the word being waited on
1156  * @mode: the task state to sleep in
1157  *
1158  * Use the standard hashed waitqueue table to wait for a bit
1159  * to be cleared and then to atomically set it.  This is similar
1160  * to wait_on_bit(), but calls io_schedule() instead of schedule()
1161  * for the actual waiting.
1162  *
1163  * Returns zero if the bit was (eventually) found to be clear and was
1164  * set.  Returns non-zero if a signal was delivered to the process and
1165  * the @mode allows that signal to wake the process.
1166  */
1167 static inline int
1168 wait_on_bit_lock_io(unsigned long *word, int bit, unsigned mode)
1169 {
1170         might_sleep();
1171         if (!test_and_set_bit(bit, word))
1172                 return 0;
1173         return out_of_line_wait_on_bit_lock(word, bit, bit_wait_io, mode);
1174 }
1175 
1176 /**
1177  * wait_on_bit_lock_action - wait for a bit to be cleared, when wanting to set it
1178  * @word: the word being waited on, a kernel virtual address
1179  * @bit: the bit of the word being waited on
1180  * @action: the function used to sleep, which may take special actions
1181  * @mode: the task state to sleep in
1182  *
1183  * Use the standard hashed waitqueue table to wait for a bit
1184  * to be cleared and then to set it, and allow the waiting action
1185  * to be specified.
1186  * This is like wait_on_bit() but allows fine control of how the waiting
1187  * is done.
1188  *
1189  * Returns zero if the bit was (eventually) found to be clear and was
1190  * set.  Returns non-zero if a signal was delivered to the process and
1191  * the @mode allows that signal to wake the process.
1192  */
1193 static inline int
1194 wait_on_bit_lock_action(unsigned long *word, int bit, wait_bit_action_f *action,
1195                         unsigned mode)
1196 {
1197         might_sleep();
1198         if (!test_and_set_bit(bit, word))
1199                 return 0;
1200         return out_of_line_wait_on_bit_lock(word, bit, action, mode);
1201 }
1202 
1203 /**
1204  * wait_on_atomic_t - Wait for an atomic_t to become 0
1205  * @val: The atomic value being waited on, a kernel virtual address
1206  * @action: the function used to sleep, which may take special actions
1207  * @mode: the task state to sleep in
1208  *
1209  * Wait for an atomic_t to become 0.  We abuse the bit-wait waitqueue table for
1210  * the purpose of getting a waitqueue, but we set the key to a bit number
1211  * outside of the target 'word'.
1212  */
1213 static inline
1214 int wait_on_atomic_t(atomic_t *val, int (*action)(atomic_t *), unsigned mode)
1215 {
1216         might_sleep();
1217         if (atomic_read(val) == 0)
1218                 return 0;
1219         return out_of_line_wait_on_atomic_t(val, action, mode);
1220 }
1221 
1222 #endif /* _LINUX_WAIT_H */
1223 

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