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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 #define __wait_event_killable_exclusive(wq, condition)                  \
604         ___wait_event(wq, condition, TASK_KILLABLE, 1, 0,               \
605                       schedule())
606 
607 #define wait_event_killable_exclusive(wq, condition)                    \
608 ({                                                                      \
609         int __ret = 0;                                                  \
610         might_sleep();                                                  \
611         if (!(condition))                                               \
612                 __ret = __wait_event_killable_exclusive(wq, condition); \
613         __ret;                                                          \
614 })
615 
616 
617 #define __wait_event_freezable_exclusive(wq, condition)                 \
618         ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 1, 0,          \
619                         schedule(); try_to_freeze())
620 
621 #define wait_event_freezable_exclusive(wq, condition)                   \
622 ({                                                                      \
623         int __ret = 0;                                                  \
624         might_sleep();                                                  \
625         if (!(condition))                                               \
626                 __ret = __wait_event_freezable_exclusive(wq, condition);\
627         __ret;                                                          \
628 })
629 
630 
631 #define __wait_event_interruptible_locked(wq, condition, exclusive, irq) \
632 ({                                                                      \
633         int __ret = 0;                                                  \
634         DEFINE_WAIT(__wait);                                            \
635         if (exclusive)                                                  \
636                 __wait.flags |= WQ_FLAG_EXCLUSIVE;                      \
637         do {                                                            \
638                 if (likely(list_empty(&__wait.task_list)))              \
639                         __add_wait_queue_tail(&(wq), &__wait);          \
640                 set_current_state(TASK_INTERRUPTIBLE);                  \
641                 if (signal_pending(current)) {                          \
642                         __ret = -ERESTARTSYS;                           \
643                         break;                                          \
644                 }                                                       \
645                 if (irq)                                                \
646                         spin_unlock_irq(&(wq).lock);                    \
647                 else                                                    \
648                         spin_unlock(&(wq).lock);                        \
649                 schedule();                                             \
650                 if (irq)                                                \
651                         spin_lock_irq(&(wq).lock);                      \
652                 else                                                    \
653                         spin_lock(&(wq).lock);                          \
654         } while (!(condition));                                         \
655         __remove_wait_queue(&(wq), &__wait);                            \
656         __set_current_state(TASK_RUNNING);                              \
657         __ret;                                                          \
658 })
659 
660 
661 /**
662  * wait_event_interruptible_locked - sleep until a condition gets true
663  * @wq: the waitqueue to wait on
664  * @condition: a C expression for the event to wait for
665  *
666  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
667  * @condition evaluates to true or a signal is received.
668  * The @condition is checked each time the waitqueue @wq is woken up.
669  *
670  * It must be called with wq.lock being held.  This spinlock is
671  * unlocked while sleeping but @condition testing is done while lock
672  * is held and when this macro exits the lock is held.
673  *
674  * The lock is locked/unlocked using spin_lock()/spin_unlock()
675  * functions which must match the way they are locked/unlocked outside
676  * of this macro.
677  *
678  * wake_up_locked() has to be called after changing any variable that could
679  * change the result of the wait condition.
680  *
681  * The function will return -ERESTARTSYS if it was interrupted by a
682  * signal and 0 if @condition evaluated to true.
683  */
684 #define wait_event_interruptible_locked(wq, condition)                  \
685         ((condition)                                                    \
686          ? 0 : __wait_event_interruptible_locked(wq, condition, 0, 0))
687 
688 /**
689  * wait_event_interruptible_locked_irq - sleep until a condition gets true
690  * @wq: the waitqueue to wait on
691  * @condition: a C expression for the event to wait for
692  *
693  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
694  * @condition evaluates to true or a signal is received.
695  * The @condition is checked each time the waitqueue @wq is woken up.
696  *
697  * It must be called with wq.lock being held.  This spinlock is
698  * unlocked while sleeping but @condition testing is done while lock
699  * is held and when this macro exits the lock is held.
700  *
701  * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq()
702  * functions which must match the way they are locked/unlocked outside
703  * of this macro.
704  *
705  * wake_up_locked() has to be called after changing any variable that could
706  * change the result of the wait condition.
707  *
708  * The function will return -ERESTARTSYS if it was interrupted by a
709  * signal and 0 if @condition evaluated to true.
710  */
711 #define wait_event_interruptible_locked_irq(wq, condition)              \
712         ((condition)                                                    \
713          ? 0 : __wait_event_interruptible_locked(wq, condition, 0, 1))
714 
715 /**
716  * wait_event_interruptible_exclusive_locked - sleep exclusively until a condition gets true
717  * @wq: the waitqueue to wait on
718  * @condition: a C expression for the event to wait for
719  *
720  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
721  * @condition evaluates to true or a signal is received.
722  * The @condition is checked each time the waitqueue @wq is woken up.
723  *
724  * It must be called with wq.lock being held.  This spinlock is
725  * unlocked while sleeping but @condition testing is done while lock
726  * is held and when this macro exits the lock is held.
727  *
728  * The lock is locked/unlocked using spin_lock()/spin_unlock()
729  * functions which must match the way they are locked/unlocked outside
730  * of this macro.
731  *
732  * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
733  * set thus when other process waits process on the list if this
734  * process is awaken further processes are not considered.
735  *
736  * wake_up_locked() has to be called after changing any variable that could
737  * change the result of the wait condition.
738  *
739  * The function will return -ERESTARTSYS if it was interrupted by a
740  * signal and 0 if @condition evaluated to true.
741  */
742 #define wait_event_interruptible_exclusive_locked(wq, condition)        \
743         ((condition)                                                    \
744          ? 0 : __wait_event_interruptible_locked(wq, condition, 1, 0))
745 
746 /**
747  * wait_event_interruptible_exclusive_locked_irq - sleep until a condition gets true
748  * @wq: the waitqueue to wait on
749  * @condition: a C expression for the event to wait for
750  *
751  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
752  * @condition evaluates to true or a signal is received.
753  * The @condition is checked each time the waitqueue @wq is woken up.
754  *
755  * It must be called with wq.lock being held.  This spinlock is
756  * unlocked while sleeping but @condition testing is done while lock
757  * is held and when this macro exits the lock is held.
758  *
759  * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq()
760  * functions which must match the way they are locked/unlocked outside
761  * of this macro.
762  *
763  * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
764  * set thus when other process waits process on the list if this
765  * process is awaken further processes are not considered.
766  *
767  * wake_up_locked() has to be called after changing any variable that could
768  * change the result of the wait condition.
769  *
770  * The function will return -ERESTARTSYS if it was interrupted by a
771  * signal and 0 if @condition evaluated to true.
772  */
773 #define wait_event_interruptible_exclusive_locked_irq(wq, condition)    \
774         ((condition)                                                    \
775          ? 0 : __wait_event_interruptible_locked(wq, condition, 1, 1))
776 
777 
778 #define __wait_event_killable(wq, condition)                            \
779         ___wait_event(wq, condition, TASK_KILLABLE, 0, 0, schedule())
780 
781 /**
782  * wait_event_killable - sleep until a condition gets true
783  * @wq: the waitqueue to wait on
784  * @condition: a C expression for the event to wait for
785  *
786  * The process is put to sleep (TASK_KILLABLE) until the
787  * @condition evaluates to true or a signal is received.
788  * The @condition is checked each time the waitqueue @wq is woken up.
789  *
790  * wake_up() has to be called after changing any variable that could
791  * change the result of the wait condition.
792  *
793  * The function will return -ERESTARTSYS if it was interrupted by a
794  * signal and 0 if @condition evaluated to true.
795  */
796 #define wait_event_killable(wq, condition)                              \
797 ({                                                                      \
798         int __ret = 0;                                                  \
799         might_sleep();                                                  \
800         if (!(condition))                                               \
801                 __ret = __wait_event_killable(wq, condition);           \
802         __ret;                                                          \
803 })
804 
805 
806 #define __wait_event_lock_irq(wq, condition, lock, cmd)                 \
807         (void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0, 0,  \
808                             spin_unlock_irq(&lock);                     \
809                             cmd;                                        \
810                             schedule();                                 \
811                             spin_lock_irq(&lock))
812 
813 /**
814  * wait_event_lock_irq_cmd - sleep until a condition gets true. The
815  *                           condition is checked under the lock. This
816  *                           is expected to be called with the lock
817  *                           taken.
818  * @wq: the waitqueue to wait on
819  * @condition: a C expression for the event to wait for
820  * @lock: a locked spinlock_t, which will be released before cmd
821  *        and schedule() and reacquired afterwards.
822  * @cmd: a command which is invoked outside the critical section before
823  *       sleep
824  *
825  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
826  * @condition evaluates to true. The @condition is checked each time
827  * the waitqueue @wq is woken up.
828  *
829  * wake_up() has to be called after changing any variable that could
830  * change the result of the wait condition.
831  *
832  * This is supposed to be called while holding the lock. The lock is
833  * dropped before invoking the cmd and going to sleep and is reacquired
834  * afterwards.
835  */
836 #define wait_event_lock_irq_cmd(wq, condition, lock, cmd)               \
837 do {                                                                    \
838         if (condition)                                                  \
839                 break;                                                  \
840         __wait_event_lock_irq(wq, condition, lock, cmd);                \
841 } while (0)
842 
843 /**
844  * wait_event_lock_irq - sleep until a condition gets true. The
845  *                       condition is checked under the lock. This
846  *                       is expected to be called with the lock
847  *                       taken.
848  * @wq: the waitqueue to wait on
849  * @condition: a C expression for the event to wait for
850  * @lock: a locked spinlock_t, which will be released before schedule()
851  *        and reacquired afterwards.
852  *
853  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
854  * @condition evaluates to true. The @condition is checked each time
855  * the waitqueue @wq is woken up.
856  *
857  * wake_up() has to be called after changing any variable that could
858  * change the result of the wait condition.
859  *
860  * This is supposed to be called while holding the lock. The lock is
861  * dropped before going to sleep and is reacquired afterwards.
862  */
863 #define wait_event_lock_irq(wq, condition, lock)                        \
864 do {                                                                    \
865         if (condition)                                                  \
866                 break;                                                  \
867         __wait_event_lock_irq(wq, condition, lock, );                   \
868 } while (0)
869 
870 
871 #define __wait_event_interruptible_lock_irq(wq, condition, lock, cmd)   \
872         ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 0, 0,          \
873                       spin_unlock_irq(&lock);                           \
874                       cmd;                                              \
875                       schedule();                                       \
876                       spin_lock_irq(&lock))
877 
878 /**
879  * wait_event_interruptible_lock_irq_cmd - sleep until a condition gets true.
880  *              The condition is checked under the lock. This is expected to
881  *              be called with the lock taken.
882  * @wq: the waitqueue to wait on
883  * @condition: a C expression for the event to wait for
884  * @lock: a locked spinlock_t, which will be released before cmd and
885  *        schedule() and reacquired afterwards.
886  * @cmd: a command which is invoked outside the critical section before
887  *       sleep
888  *
889  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
890  * @condition evaluates to true or a signal is received. The @condition is
891  * checked each time the waitqueue @wq is woken up.
892  *
893  * wake_up() has to be called after changing any variable that could
894  * change the result of the wait condition.
895  *
896  * This is supposed to be called while holding the lock. The lock is
897  * dropped before invoking the cmd and going to sleep and is reacquired
898  * afterwards.
899  *
900  * The macro will return -ERESTARTSYS if it was interrupted by a signal
901  * and 0 if @condition evaluated to true.
902  */
903 #define wait_event_interruptible_lock_irq_cmd(wq, condition, lock, cmd) \
904 ({                                                                      \
905         int __ret = 0;                                                  \
906         if (!(condition))                                               \
907                 __ret = __wait_event_interruptible_lock_irq(wq,         \
908                                                 condition, lock, cmd);  \
909         __ret;                                                          \
910 })
911 
912 /**
913  * wait_event_interruptible_lock_irq - sleep until a condition gets true.
914  *              The condition is checked under the lock. This is expected
915  *              to be called with the lock taken.
916  * @wq: the waitqueue to wait on
917  * @condition: a C expression for the event to wait for
918  * @lock: a locked spinlock_t, which will be released before schedule()
919  *        and reacquired afterwards.
920  *
921  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
922  * @condition evaluates to true or signal is received. The @condition is
923  * checked each time the waitqueue @wq is woken up.
924  *
925  * wake_up() has to be called after changing any variable that could
926  * change the result of the wait condition.
927  *
928  * This is supposed to be called while holding the lock. The lock is
929  * dropped before going to sleep and is reacquired afterwards.
930  *
931  * The macro will return -ERESTARTSYS if it was interrupted by a signal
932  * and 0 if @condition evaluated to true.
933  */
934 #define wait_event_interruptible_lock_irq(wq, condition, lock)          \
935 ({                                                                      \
936         int __ret = 0;                                                  \
937         if (!(condition))                                               \
938                 __ret = __wait_event_interruptible_lock_irq(wq,         \
939                                                 condition, lock,);      \
940         __ret;                                                          \
941 })
942 
943 #define __wait_event_interruptible_lock_irq_timeout(wq, condition,      \
944                                                     lock, timeout)      \
945         ___wait_event(wq, ___wait_cond_timeout(condition),              \
946                       TASK_INTERRUPTIBLE, 0, timeout,                   \
947                       spin_unlock_irq(&lock);                           \
948                       __ret = schedule_timeout(__ret);                  \
949                       spin_lock_irq(&lock));
950 
951 /**
952  * wait_event_interruptible_lock_irq_timeout - sleep until a condition gets
953  *              true or a timeout elapses. The condition is checked under
954  *              the lock. This is expected to be called with the lock taken.
955  * @wq: the waitqueue to wait on
956  * @condition: a C expression for the event to wait for
957  * @lock: a locked spinlock_t, which will be released before schedule()
958  *        and reacquired afterwards.
959  * @timeout: timeout, in jiffies
960  *
961  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
962  * @condition evaluates to true or signal is received. The @condition is
963  * checked each time the waitqueue @wq is woken up.
964  *
965  * wake_up() has to be called after changing any variable that could
966  * change the result of the wait condition.
967  *
968  * This is supposed to be called while holding the lock. The lock is
969  * dropped before going to sleep and is reacquired afterwards.
970  *
971  * The function returns 0 if the @timeout elapsed, -ERESTARTSYS if it
972  * was interrupted by a signal, and the remaining jiffies otherwise
973  * if the condition evaluated to true before the timeout elapsed.
974  */
975 #define wait_event_interruptible_lock_irq_timeout(wq, condition, lock,  \
976                                                   timeout)              \
977 ({                                                                      \
978         long __ret = timeout;                                           \
979         if (!___wait_cond_timeout(condition))                           \
980                 __ret = __wait_event_interruptible_lock_irq_timeout(    \
981                                         wq, condition, lock, timeout);  \
982         __ret;                                                          \
983 })
984 
985 /*
986  * Waitqueues which are removed from the waitqueue_head at wakeup time
987  */
988 void prepare_to_wait(wait_queue_head_t *q, wait_queue_t *wait, int state);
989 void prepare_to_wait_exclusive(wait_queue_head_t *q, wait_queue_t *wait, int state);
990 long prepare_to_wait_event(wait_queue_head_t *q, wait_queue_t *wait, int state);
991 void finish_wait(wait_queue_head_t *q, wait_queue_t *wait);
992 void abort_exclusive_wait(wait_queue_head_t *q, wait_queue_t *wait, unsigned int mode, void *key);
993 long wait_woken(wait_queue_t *wait, unsigned mode, long timeout);
994 int woken_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
995 int autoremove_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
996 int wake_bit_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
997 
998 #define DEFINE_WAIT_FUNC(name, function)                                \
999         wait_queue_t name = {                                           \
1000                 .private        = current,                              \
1001                 .func           = function,                             \
1002                 .task_list      = LIST_HEAD_INIT((name).task_list),     \
1003         }
1004 
1005 #define DEFINE_WAIT(name) DEFINE_WAIT_FUNC(name, autoremove_wake_function)
1006 
1007 #define DEFINE_WAIT_BIT(name, word, bit)                                \
1008         struct wait_bit_queue name = {                                  \
1009                 .key = __WAIT_BIT_KEY_INITIALIZER(word, bit),           \
1010                 .wait   = {                                             \
1011                         .private        = current,                      \
1012                         .func           = wake_bit_function,            \
1013                         .task_list      =                               \
1014                                 LIST_HEAD_INIT((name).wait.task_list),  \
1015                 },                                                      \
1016         }
1017 
1018 #define init_wait(wait)                                                 \
1019         do {                                                            \
1020                 (wait)->private = current;                              \
1021                 (wait)->func = autoremove_wake_function;                \
1022                 INIT_LIST_HEAD(&(wait)->task_list);                     \
1023                 (wait)->flags = 0;                                      \
1024         } while (0)
1025 
1026 
1027 extern int bit_wait(struct wait_bit_key *, int);
1028 extern int bit_wait_io(struct wait_bit_key *, int);
1029 extern int bit_wait_timeout(struct wait_bit_key *, int);
1030 extern int bit_wait_io_timeout(struct wait_bit_key *, int);
1031 
1032 /**
1033  * wait_on_bit - wait for a bit to be cleared
1034  * @word: the word being waited on, a kernel virtual address
1035  * @bit: the bit of the word being waited on
1036  * @mode: the task state to sleep in
1037  *
1038  * There is a standard hashed waitqueue table for generic use. This
1039  * is the part of the hashtable's accessor API that waits on a bit.
1040  * For instance, if one were to have waiters on a bitflag, one would
1041  * call wait_on_bit() in threads waiting for the bit to clear.
1042  * One uses wait_on_bit() where one is waiting for the bit to clear,
1043  * but has no intention of setting it.
1044  * Returned value will be zero if the bit was cleared, or non-zero
1045  * if the process received a signal and the mode permitted wakeup
1046  * on that signal.
1047  */
1048 static inline int
1049 wait_on_bit(unsigned long *word, int bit, unsigned mode)
1050 {
1051         might_sleep();
1052         if (!test_bit(bit, word))
1053                 return 0;
1054         return out_of_line_wait_on_bit(word, bit,
1055                                        bit_wait,
1056                                        mode);
1057 }
1058 
1059 /**
1060  * wait_on_bit_io - wait for a bit to be cleared
1061  * @word: the word being waited on, a kernel virtual address
1062  * @bit: the bit of the word being waited on
1063  * @mode: the task state to sleep in
1064  *
1065  * Use the standard hashed waitqueue table to wait for a bit
1066  * to be cleared.  This is similar to wait_on_bit(), but calls
1067  * io_schedule() instead of schedule() for the actual waiting.
1068  *
1069  * Returned value will be zero if the bit was cleared, or non-zero
1070  * if the process received a signal and the mode permitted wakeup
1071  * on that signal.
1072  */
1073 static inline int
1074 wait_on_bit_io(unsigned long *word, int bit, unsigned mode)
1075 {
1076         might_sleep();
1077         if (!test_bit(bit, word))
1078                 return 0;
1079         return out_of_line_wait_on_bit(word, bit,
1080                                        bit_wait_io,
1081                                        mode);
1082 }
1083 
1084 /**
1085  * wait_on_bit_timeout - wait for a bit to be cleared or a timeout elapses
1086  * @word: the word being waited on, a kernel virtual address
1087  * @bit: the bit of the word being waited on
1088  * @mode: the task state to sleep in
1089  * @timeout: timeout, in jiffies
1090  *
1091  * Use the standard hashed waitqueue table to wait for a bit
1092  * to be cleared. This is similar to wait_on_bit(), except also takes a
1093  * timeout parameter.
1094  *
1095  * Returned value will be zero if the bit was cleared before the
1096  * @timeout elapsed, or non-zero if the @timeout elapsed or process
1097  * received a signal and the mode permitted wakeup on that signal.
1098  */
1099 static inline int
1100 wait_on_bit_timeout(unsigned long *word, int bit, unsigned mode,
1101                     unsigned long timeout)
1102 {
1103         might_sleep();
1104         if (!test_bit(bit, word))
1105                 return 0;
1106         return out_of_line_wait_on_bit_timeout(word, bit,
1107                                                bit_wait_timeout,
1108                                                mode, timeout);
1109 }
1110 
1111 /**
1112  * wait_on_bit_action - wait for a bit to be cleared
1113  * @word: the word being waited on, a kernel virtual address
1114  * @bit: the bit of the word being waited on
1115  * @action: the function used to sleep, which may take special actions
1116  * @mode: the task state to sleep in
1117  *
1118  * Use the standard hashed waitqueue table to wait for a bit
1119  * to be cleared, and allow the waiting action to be specified.
1120  * This is like wait_on_bit() but allows fine control of how the waiting
1121  * is done.
1122  *
1123  * Returned value will be zero if the bit was cleared, or non-zero
1124  * if the process received a signal and the mode permitted wakeup
1125  * on that signal.
1126  */
1127 static inline int
1128 wait_on_bit_action(unsigned long *word, int bit, wait_bit_action_f *action,
1129                    unsigned mode)
1130 {
1131         might_sleep();
1132         if (!test_bit(bit, word))
1133                 return 0;
1134         return out_of_line_wait_on_bit(word, bit, action, mode);
1135 }
1136 
1137 /**
1138  * wait_on_bit_lock - wait for a bit to be cleared, when wanting to set it
1139  * @word: the word being waited on, a kernel virtual address
1140  * @bit: the bit of the word being waited on
1141  * @mode: the task state to sleep in
1142  *
1143  * There is a standard hashed waitqueue table for generic use. This
1144  * is the part of the hashtable's accessor API that waits on a bit
1145  * when one intends to set it, for instance, trying to lock bitflags.
1146  * For instance, if one were to have waiters trying to set bitflag
1147  * and waiting for it to clear before setting it, one would call
1148  * wait_on_bit() in threads waiting to be able to set the bit.
1149  * One uses wait_on_bit_lock() where one is waiting for the bit to
1150  * clear with the intention of setting it, and when done, clearing it.
1151  *
1152  * Returns zero if the bit was (eventually) found to be clear and was
1153  * set.  Returns non-zero if a signal was delivered to the process and
1154  * the @mode allows that signal to wake the process.
1155  */
1156 static inline int
1157 wait_on_bit_lock(unsigned long *word, int bit, unsigned mode)
1158 {
1159         might_sleep();
1160         if (!test_and_set_bit(bit, word))
1161                 return 0;
1162         return out_of_line_wait_on_bit_lock(word, bit, bit_wait, mode);
1163 }
1164 
1165 /**
1166  * wait_on_bit_lock_io - wait for a bit to be cleared, when wanting to set it
1167  * @word: the word being waited on, a kernel virtual address
1168  * @bit: the bit of the word being waited on
1169  * @mode: the task state to sleep in
1170  *
1171  * Use the standard hashed waitqueue table to wait for a bit
1172  * to be cleared and then to atomically set it.  This is similar
1173  * to wait_on_bit(), but calls io_schedule() instead of schedule()
1174  * for the actual waiting.
1175  *
1176  * Returns zero if the bit was (eventually) found to be clear and was
1177  * set.  Returns non-zero if a signal was delivered to the process and
1178  * the @mode allows that signal to wake the process.
1179  */
1180 static inline int
1181 wait_on_bit_lock_io(unsigned long *word, int bit, unsigned mode)
1182 {
1183         might_sleep();
1184         if (!test_and_set_bit(bit, word))
1185                 return 0;
1186         return out_of_line_wait_on_bit_lock(word, bit, bit_wait_io, mode);
1187 }
1188 
1189 /**
1190  * wait_on_bit_lock_action - wait for a bit to be cleared, when wanting to set it
1191  * @word: the word being waited on, a kernel virtual address
1192  * @bit: the bit of the word being waited on
1193  * @action: the function used to sleep, which may take special actions
1194  * @mode: the task state to sleep in
1195  *
1196  * Use the standard hashed waitqueue table to wait for a bit
1197  * to be cleared and then to set it, and allow the waiting action
1198  * to be specified.
1199  * This is like wait_on_bit() but allows fine control of how the waiting
1200  * is done.
1201  *
1202  * Returns zero if the bit was (eventually) found to be clear and was
1203  * set.  Returns non-zero if a signal was delivered to the process and
1204  * the @mode allows that signal to wake the process.
1205  */
1206 static inline int
1207 wait_on_bit_lock_action(unsigned long *word, int bit, wait_bit_action_f *action,
1208                         unsigned mode)
1209 {
1210         might_sleep();
1211         if (!test_and_set_bit(bit, word))
1212                 return 0;
1213         return out_of_line_wait_on_bit_lock(word, bit, action, mode);
1214 }
1215 
1216 /**
1217  * wait_on_atomic_t - Wait for an atomic_t to become 0
1218  * @val: The atomic value being waited on, a kernel virtual address
1219  * @action: the function used to sleep, which may take special actions
1220  * @mode: the task state to sleep in
1221  *
1222  * Wait for an atomic_t to become 0.  We abuse the bit-wait waitqueue table for
1223  * the purpose of getting a waitqueue, but we set the key to a bit number
1224  * outside of the target 'word'.
1225  */
1226 static inline
1227 int wait_on_atomic_t(atomic_t *val, int (*action)(atomic_t *), unsigned mode)
1228 {
1229         might_sleep();
1230         if (atomic_read(val) == 0)
1231                 return 0;
1232         return out_of_line_wait_on_atomic_t(val, action, mode);
1233 }
1234 
1235 #endif /* _LINUX_WAIT_H */
1236 

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