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