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