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