include/linux/wait.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _LINUX_WAIT_H
   3 #define _LINUX_WAIT_H
   4 /*
   5  * Linux wait queue related types and methods
   6  */
   7 #include <linux/list.h>
   8 #include <linux/stddef.h>
   9 #include <linux/spinlock.h>
  10
  11 #include <asm/current.h>
  12 #include <uapi/linux/wait.h>
  13
  14 typedef struct wait_queue_entry wait_queue_entry_t;
  15
  16 typedef int (*wait_queue_func_t)(struct wait_queue_entry *wq_entry, unsigned mode, int flags, void *key);
  17 int default_wake_function(struct wait_queue_entry *wq_entry, unsigned mode, int flags, void *key);
  18
  19 /* wait_queue_entry::flags */
  20 #define WQ_FLAG_EXCLUSIVE       0x01
  21 #define WQ_FLAG_WOKEN           0x02
  22 #define WQ_FLAG_BOOKMARK        0x04
  23
  24 /*
  25  * A single wait-queue entry structure:
  26  */
  27 struct wait_queue_entry {
  28         unsigned int            flags;
  29         void                    *private;
  30         wait_queue_func_t       func;
  31         struct list_head        entry;
  32 };
  33
  34 struct wait_queue_head {
  35         spinlock_t              lock;
  36         struct list_head        head;
  37 };
  38 typedef struct wait_queue_head wait_queue_head_t;
  39
  40 struct task_struct;
  41
  42 /*
  43  * Macros for declaration and initialisaton of the datatypes
  44  */
  45
  46 #define __WAITQUEUE_INITIALIZER(name, tsk) {                                    \
  47         .private        = tsk,                                                  \
  48         .func           = default_wake_function,                                \
  49         .entry          = { NULL, NULL } }
  50
  51 #define DECLARE_WAITQUEUE(name, tsk)                                            \
  52         struct wait_queue_entry name = __WAITQUEUE_INITIALIZER(name, tsk)
  53
  54 #define __WAIT_QUEUE_HEAD_INITIALIZER(name) {                                   \
  55         .lock           = __SPIN_LOCK_UNLOCKED(name.lock),                      \
  56         .head           = { &(name).head, &(name).head } }
  57
  58 #define DECLARE_WAIT_QUEUE_HEAD(name) \
  59         struct wait_queue_head name = __WAIT_QUEUE_HEAD_INITIALIZER(name)
  60
  61 extern void __init_waitqueue_head(struct wait_queue_head *wq_head, const char *name, struct lock_class_key *);
  62
  63 #define init_waitqueue_head(wq_head)                                            \
  64         do {                                                                    \
  65                 static struct lock_class_key __key;                             \
  66                                                                                 \
  67                 __init_waitqueue_head((wq_head), #wq_head, &__key);             \
  68         } while (0)
  69
  70 #ifdef CONFIG_LOCKDEP
  71 # define __WAIT_QUEUE_HEAD_INIT_ONSTACK(name) \
  72         ({ init_waitqueue_head(&name); name; })
  73 # define DECLARE_WAIT_QUEUE_HEAD_ONSTACK(name) \
  74         struct wait_queue_head name = __WAIT_QUEUE_HEAD_INIT_ONSTACK(name)
  75 #else
  76 # define DECLARE_WAIT_QUEUE_HEAD_ONSTACK(name) DECLARE_WAIT_QUEUE_HEAD(name)
  77 #endif
  78
  79 static inline void init_waitqueue_entry(struct wait_queue_entry *wq_entry, struct task_struct *p)
  80 {
  81         wq_entry->flags         = 0;
  82         wq_entry->private       = p;
  83         wq_entry->func          = default_wake_function;
  84 }
  85
  86 static inline void
  87 init_waitqueue_func_entry(struct wait_queue_entry *wq_entry, wait_queue_func_t func)
  88 {
  89         wq_entry->flags         = 0;
  90         wq_entry->private       = NULL;
  91         wq_entry->func          = func;
  92 }
  93
  94 /**
  95  * waitqueue_active -- locklessly test for waiters on the queue
  96  * @wq_head: the waitqueue to test for waiters
  97  *
  98  * returns true if the wait list is not empty
  99  *
 100  * NOTE: this function is lockless and requires care, incorrect usage _will_
 101  * lead to sporadic and non-obvious failure.
 102  *
 103  * Use either while holding wait_queue_head::lock or when used for wakeups
 104  * with an extra smp_mb() like:
 105  *
 106  *      CPU0 - waker                    CPU1 - waiter
 107  *
 108  *                                      for (;;) {
 109  *      @cond = true;                     prepare_to_wait(&wq_head, &wait, state);
 110  *      smp_mb();                         // smp_mb() from set_current_state()
 111  *      if (waitqueue_active(wq_head))         if (@cond)
 112  *        wake_up(wq_head);                      break;
 113  *                                        schedule();
 114  *                                      }
 115  *                                      finish_wait(&wq_head, &wait);
 116  *
 117  * Because without the explicit smp_mb() it's possible for the
 118  * waitqueue_active() load to get hoisted over the @cond store such that we'll
 119  * observe an empty wait list while the waiter might not observe @cond.
 120  *
 121  * Also note that this 'optimization' trades a spin_lock() for an smp_mb(),
 122  * which (when the lock is uncontended) are of roughly equal cost.
 123  */
 124 static inline int waitqueue_active(struct wait_queue_head *wq_head)
 125 {
 126         return !list_empty(&wq_head->head);
 127 }
 128
 129 /**
 130  * wq_has_sleeper - check if there are any waiting processes
 131  * @wq_head: wait queue head
 132  *
 133  * Returns true if wq_head has waiting processes
 134  *
 135  * Please refer to the comment for waitqueue_active.
 136  */
 137 static inline bool wq_has_sleeper(struct wait_queue_head *wq_head)
 138 {
 139         /*
 140          * We need to be sure we are in sync with the
 141          * add_wait_queue modifications to the wait queue.
 142          *
 143          * This memory barrier should be paired with one on the
 144          * waiting side.
 145          */
 146         smp_mb();
 147         return waitqueue_active(wq_head);
 148 }
 149
 150 extern void add_wait_queue(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry);
 151 extern void add_wait_queue_exclusive(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry);
 152 extern void remove_wait_queue(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry);
 153
 154 static inline void __add_wait_queue(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry)
 155 {
 156         list_add(&wq_entry->entry, &wq_head->head);
 157 }
 158
 159 /*
 160  * Used for wake-one threads:
 161  */
 162 static inline void
 163 __add_wait_queue_exclusive(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry)
 164 {
 165         wq_entry->flags |= WQ_FLAG_EXCLUSIVE;
 166         __add_wait_queue(wq_head, wq_entry);
 167 }
 168
 169 static inline void __add_wait_queue_entry_tail(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry)
 170 {
 171         list_add_tail(&wq_entry->entry, &wq_head->head);
 172 }
 173
 174 static inline void
 175 __add_wait_queue_entry_tail_exclusive(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry)
 176 {
 177         wq_entry->flags |= WQ_FLAG_EXCLUSIVE;
 178         __add_wait_queue_entry_tail(wq_head, wq_entry);
 179 }
 180
 181 static inline void
 182 __remove_wait_queue(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry)
 183 {
 184         list_del(&wq_entry->entry);
 185 }
 186
 187 void __wake_up(struct wait_queue_head *wq_head, unsigned int mode, int nr, void *key);
 188 void __wake_up_locked_key(struct wait_queue_head *wq_head, unsigned int mode, void *key);
 189 void __wake_up_locked_key_bookmark(struct wait_queue_head *wq_head,
 190                 unsigned int mode, void *key, wait_queue_entry_t *bookmark);
 191 void __wake_up_sync_key(struct wait_queue_head *wq_head, unsigned int mode, int nr, void *key);
 192 void __wake_up_locked(struct wait_queue_head *wq_head, unsigned int mode, int nr);
 193 void __wake_up_sync(struct wait_queue_head *wq_head, unsigned int mode, int nr);
 194
 195 #define wake_up(x)                      __wake_up(x, TASK_NORMAL, 1, NULL)
 196 #define wake_up_nr(x, nr)               __wake_up(x, TASK_NORMAL, nr, NULL)
 197 #define wake_up_all(x)                  __wake_up(x, TASK_NORMAL, 0, NULL)
 198 #define wake_up_locked(x)               __wake_up_locked((x), TASK_NORMAL, 1)
 199 #define wake_up_all_locked(x)           __wake_up_locked((x), TASK_NORMAL, 0)
 200
 201 #define wake_up_interruptible(x)        __wake_up(x, TASK_INTERRUPTIBLE, 1, NULL)
 202 #define wake_up_interruptible_nr(x, nr) __wake_up(x, TASK_INTERRUPTIBLE, nr, NULL)
 203 #define wake_up_interruptible_all(x)    __wake_up(x, TASK_INTERRUPTIBLE, 0, NULL)
 204 #define wake_up_interruptible_sync(x)   __wake_up_sync((x), TASK_INTERRUPTIBLE, 1)
 205
 206 /*
 207  * Wakeup macros to be used to report events to the targets.
 208  */
 209 #define poll_to_key(m) ((void *)(__force uintptr_t)(__poll_t)(m))
 210 #define key_to_poll(m) ((__force __poll_t)(uintptr_t)(void *)(m))
 211 #define wake_up_poll(x, m)                                                      \
 212         __wake_up(x, TASK_NORMAL, 1, poll_to_key(m))
 213 #define wake_up_locked_poll(x, m)                                               \
 214         __wake_up_locked_key((x), TASK_NORMAL, poll_to_key(m))
 215 #define wake_up_interruptible_poll(x, m)                                        \
 216         __wake_up(x, TASK_INTERRUPTIBLE, 1, poll_to_key(m))
 217 #define wake_up_interruptible_sync_poll(x, m)                                   \
 218         __wake_up_sync_key((x), TASK_INTERRUPTIBLE, 1, poll_to_key(m))
 219
 220 #define ___wait_cond_timeout(condition)                                         \
 221 ({                                                                              \
 222         bool __cond = (condition);                                              \
 223         if (__cond && !__ret)                                                   \
 224                 __ret = 1;                                                      \
 225         __cond || !__ret;                                                       \
 226 })
 227
 228 #define ___wait_is_interruptible(state)                                         \
 229         (!__builtin_constant_p(state) ||                                        \
 230                 state == TASK_INTERRUPTIBLE || state == TASK_KILLABLE)          \
 231
 232 extern void init_wait_entry(struct wait_queue_entry *wq_entry, int flags);
 233
 234 /*
 235  * The below macro ___wait_event() has an explicit shadow of the __ret
 236  * variable when used from the wait_event_*() macros.
 237  *
 238  * This is so that both can use the ___wait_cond_timeout() construct
 239  * to wrap the condition.
 240  *
 241  * The type inconsistency of the wait_event_*() __ret variable is also
 242  * on purpose; we use long where we can return timeout values and int
 243  * otherwise.
 244  */
 245
 246 #define ___wait_event(wq_head, condition, state, exclusive, ret, cmd)           \
 247 ({                                                                              \
 248         __label__ __out;                                                        \
 249         struct wait_queue_entry __wq_entry;                                     \
 250         long __ret = ret;       /* explicit shadow */                           \
 251                                                                                 \
 252         init_wait_entry(&__wq_entry, exclusive ? WQ_FLAG_EXCLUSIVE : 0);        \
 253         for (;;) {                                                              \
 254                 long __int = prepare_to_wait_event(&wq_head, &__wq_entry, state);\
 255                                                                                 \
 256                 if (condition)                                                  \
 257                         break;                                                  \
 258                                                                                 \
 259                 if (___wait_is_interruptible(state) && __int) {                 \
 260                         __ret = __int;                                          \
 261                         goto __out;                                             \
 262                 }                                                               \
 263                                                                                 \
 264                 cmd;                                                            \
 265         }                                                                       \
 266         finish_wait(&wq_head, &__wq_entry);                                     \
 267 __out:  __ret;                                                                  \
 268 })
 269
 270 #define __wait_event(wq_head, condition)                                        \
 271         (void)___wait_event(wq_head, condition, TASK_UNINTERRUPTIBLE, 0, 0,     \
 272                             schedule())
 273
 274 /**
 275  * wait_event - sleep until a condition gets true
 276  * @wq_head: 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_UNINTERRUPTIBLE) until the
 280  * @condition evaluates to true. The @condition is checked each time
 281  * the waitqueue @wq_head 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(wq_head, condition)                                          \
 287 do {                                                                            \
 288         might_sleep();                                                          \
 289         if (condition)                                                          \
 290                 break;                                                          \
 291         __wait_event(wq_head, condition);                                       \
 292 } while (0)
 293
 294 #define __io_wait_event(wq_head, condition)                                     \
 295         (void)___wait_event(wq_head, condition, TASK_UNINTERRUPTIBLE, 0, 0,     \
 296                             io_schedule())
 297
 298 /*
 299  * io_wait_event() -- like wait_event() but with io_schedule()
 300  */
 301 #define io_wait_event(wq_head, condition)                                       \
 302 do {                                                                            \
 303         might_sleep();                                                          \
 304         if (condition)                                                          \
 305                 break;                                                          \
 306         __io_wait_event(wq_head, condition);                                    \
 307 } while (0)
 308
 309 #define __wait_event_freezable(wq_head, condition)                              \
 310         ___wait_event(wq_head, condition, TASK_INTERRUPTIBLE, 0, 0,             \
 311                             schedule(); try_to_freeze())
 312
 313 /**
 314  * wait_event_freezable - sleep (or freeze) until a condition gets true
 315  * @wq_head: the waitqueue to wait on
 316  * @condition: a C expression for the event to wait for
 317  *
 318  * The process is put to sleep (TASK_INTERRUPTIBLE -- so as not to contribute
 319  * to system load) until the @condition evaluates to true. The
 320  * @condition is checked each time the waitqueue @wq_head is woken up.
 321  *
 322  * wake_up() has to be called after changing any variable that could
 323  * change the result of the wait condition.
 324  */
 325 #define wait_event_freezable(wq_head, condition)                                \
 326 ({                                                                              \
 327         int __ret = 0;                                                          \
 328         might_sleep();                                                          \
 329         if (!(condition))                                                       \
 330                 __ret = __wait_event_freezable(wq_head, condition);             \
 331         __ret;                                                                  \
 332 })
 333
 334 #define __wait_event_timeout(wq_head, condition, timeout)                       \
 335         ___wait_event(wq_head, ___wait_cond_timeout(condition),                 \
 336                       TASK_UNINTERRUPTIBLE, 0, timeout,                         \
 337                       __ret = schedule_timeout(__ret))
 338
 339 /**
 340  * wait_event_timeout - sleep until a condition gets true or a timeout elapses
 341  * @wq_head: the waitqueue to wait on
 342  * @condition: a C expression for the event to wait for
 343  * @timeout: timeout, in jiffies
 344  *
 345  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 346  * @condition evaluates to true. The @condition is checked each time
 347  * the waitqueue @wq_head is woken up.
 348  *
 349  * wake_up() has to be called after changing any variable that could
 350  * change the result of the wait condition.
 351  *
 352  * Returns:
 353  * 0 if the @condition evaluated to %false after the @timeout elapsed,
 354  * 1 if the @condition evaluated to %true after the @timeout elapsed,
 355  * or the remaining jiffies (at least 1) if the @condition evaluated
 356  * to %true before the @timeout elapsed.
 357  */
 358 #define wait_event_timeout(wq_head, condition, timeout)                         \
 359 ({                                                                              \
 360         long __ret = timeout;                                                   \
 361         might_sleep();                                                          \
 362         if (!___wait_cond_timeout(condition))                                   \
 363                 __ret = __wait_event_timeout(wq_head, condition, timeout);      \
 364         __ret;                                                                  \
 365 })
 366
 367 #define __wait_event_freezable_timeout(wq_head, condition, timeout)             \
 368         ___wait_event(wq_head, ___wait_cond_timeout(condition),                 \
 369                       TASK_INTERRUPTIBLE, 0, timeout,                           \
 370                       __ret = schedule_timeout(__ret); try_to_freeze())
 371
 372 /*
 373  * like wait_event_timeout() -- except it uses TASK_INTERRUPTIBLE to avoid
 374  * increasing load and is freezable.
 375  */
 376 #define wait_event_freezable_timeout(wq_head, condition, timeout)               \
 377 ({                                                                              \
 378         long __ret = timeout;                                                   \
 379         might_sleep();                                                          \
 380         if (!___wait_cond_timeout(condition))                                   \
 381                 __ret = __wait_event_freezable_timeout(wq_head, condition, timeout); \
 382         __ret;                                                                  \
 383 })
 384
 385 #define __wait_event_exclusive_cmd(wq_head, condition, cmd1, cmd2)              \
 386         (void)___wait_event(wq_head, condition, TASK_UNINTERRUPTIBLE, 1, 0,     \
 387                             cmd1; schedule(); cmd2)
 388 /*
 389  * Just like wait_event_cmd(), except it sets exclusive flag
 390  */
 391 #define wait_event_exclusive_cmd(wq_head, condition, cmd1, cmd2)                \
 392 do {                                                                            \
 393         if (condition)                                                          \
 394                 break;                                                          \
 395         __wait_event_exclusive_cmd(wq_head, condition, cmd1, cmd2);             \
 396 } while (0)
 397
 398 #define __wait_event_cmd(wq_head, condition, cmd1, cmd2)                        \
 399         (void)___wait_event(wq_head, condition, TASK_UNINTERRUPTIBLE, 0, 0,     \
 400                             cmd1; schedule(); cmd2)
 401
 402 /**
 403  * wait_event_cmd - sleep until a condition gets true
 404  * @wq_head: the waitqueue to wait on
 405  * @condition: a C expression for the event to wait for
 406  * @cmd1: the command will be executed before sleep
 407  * @cmd2: the command will be executed after sleep
 408  *
 409  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 410  * @condition evaluates to true. The @condition is checked each time
 411  * the waitqueue @wq_head is woken up.
 412  *
 413  * wake_up() has to be called after changing any variable that could
 414  * change the result of the wait condition.
 415  */
 416 #define wait_event_cmd(wq_head, condition, cmd1, cmd2)                          \
 417 do {                                                                            \
 418         if (condition)                                                          \
 419                 break;                                                          \
 420         __wait_event_cmd(wq_head, condition, cmd1, cmd2);                       \
 421 } while (0)
 422
 423 #define __wait_event_interruptible(wq_head, condition)                          \
 424         ___wait_event(wq_head, condition, TASK_INTERRUPTIBLE, 0, 0,             \
 425                       schedule())
 426
 427 /**
 428  * wait_event_interruptible - sleep until a condition gets true
 429  * @wq_head: the waitqueue to wait on
 430  * @condition: a C expression for the event to wait for
 431  *
 432  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 433  * @condition evaluates to true or a signal is received.
 434  * The @condition is checked each time the waitqueue @wq_head 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  * The function will return -ERESTARTSYS if it was interrupted by a
 440  * signal and 0 if @condition evaluated to true.
 441  */
 442 #define wait_event_interruptible(wq_head, condition)                            \
 443 ({                                                                              \
 444         int __ret = 0;                                                          \
 445         might_sleep();                                                          \
 446         if (!(condition))                                                       \
 447                 __ret = __wait_event_interruptible(wq_head, condition);         \
 448         __ret;                                                                  \
 449 })
 450
 451 #define __wait_event_interruptible_timeout(wq_head, condition, timeout)         \
 452         ___wait_event(wq_head, ___wait_cond_timeout(condition),                 \
 453                       TASK_INTERRUPTIBLE, 0, timeout,                           \
 454                       __ret = schedule_timeout(__ret))
 455
 456 /**
 457  * wait_event_interruptible_timeout - sleep until a condition gets true or a timeout elapses
 458  * @wq_head: the waitqueue to wait on
 459  * @condition: a C expression for the event to wait for
 460  * @timeout: timeout, in jiffies
 461  *
 462  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 463  * @condition evaluates to true or a signal is received.
 464  * The @condition is checked each time the waitqueue @wq_head is woken up.
 465  *
 466  * wake_up() has to be called after changing any variable that could
 467  * change the result of the wait condition.
 468  *
 469  * Returns:
 470  * 0 if the @condition evaluated to %false after the @timeout elapsed,
 471  * 1 if the @condition evaluated to %true after the @timeout elapsed,
 472  * the remaining jiffies (at least 1) if the @condition evaluated
 473  * to %true before the @timeout elapsed, or -%ERESTARTSYS if it was
 474  * interrupted by a signal.
 475  */
 476 #define wait_event_interruptible_timeout(wq_head, condition, timeout)           \
 477 ({                                                                              \
 478         long __ret = timeout;                                                   \
 479         might_sleep();                                                          \
 480         if (!___wait_cond_timeout(condition))                                   \
 481                 __ret = __wait_event_interruptible_timeout(wq_head,             \
 482                                                 condition, timeout);            \
 483         __ret;                                                                  \
 484 })
 485
 486 #define __wait_event_hrtimeout(wq_head, condition, timeout, state)              \
 487 ({                                                                              \
 488         int __ret = 0;                                                          \
 489         struct hrtimer_sleeper __t;                                             \
 490                                                                                 \
 491         hrtimer_init_on_stack(&__t.timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);   \
 492         hrtimer_init_sleeper(&__t, current);                                    \
 493         if ((timeout) != KTIME_MAX)                                             \
 494                 hrtimer_start_range_ns(&__t.timer, timeout,                     \
 495                                        current->timer_slack_ns,                 \
 496                                        HRTIMER_MODE_REL);                       \
 497                                                                                 \
 498         __ret = ___wait_event(wq_head, condition, state, 0, 0,                  \
 499                 if (!__t.task) {                                                \
 500                         __ret = -ETIME;                                         \
 501                         break;                                                  \
 502                 }                                                               \
 503                 schedule());                                                    \
 504                                                                                 \
 505         hrtimer_cancel(&__t.timer);                                             \
 506         destroy_hrtimer_on_stack(&__t.timer);                                   \
 507         __ret;                                                                  \
 508 })
 509
 510 /**
 511  * wait_event_hrtimeout - sleep until a condition gets true or a timeout elapses
 512  * @wq_head: the waitqueue to wait on
 513  * @condition: a C expression for the event to wait for
 514  * @timeout: timeout, as a ktime_t
 515  *
 516  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 517  * @condition evaluates to true or a signal is received.
 518  * The @condition is checked each time the waitqueue @wq_head is woken up.
 519  *
 520  * wake_up() has to be called after changing any variable that could
 521  * change the result of the wait condition.
 522  *
 523  * The function returns 0 if @condition became true, or -ETIME if the timeout
 524  * elapsed.
 525  */
 526 #define wait_event_hrtimeout(wq_head, condition, timeout)                       \
 527 ({                                                                              \
 528         int __ret = 0;                                                          \
 529         might_sleep();                                                          \
 530         if (!(condition))                                                       \
 531                 __ret = __wait_event_hrtimeout(wq_head, condition, timeout,     \
 532                                                TASK_UNINTERRUPTIBLE);           \
 533         __ret;                                                                  \
 534 })
 535
 536 /**
 537  * wait_event_interruptible_hrtimeout - sleep until a condition gets true or a timeout elapses
 538  * @wq: the waitqueue to wait on
 539  * @condition: a C expression for the event to wait for
 540  * @timeout: timeout, as a ktime_t
 541  *
 542  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 543  * @condition evaluates to true or a signal is received.
 544  * The @condition is checked each time the waitqueue @wq is woken up.
 545  *
 546  * wake_up() has to be called after changing any variable that could
 547  * change the result of the wait condition.
 548  *
 549  * The function returns 0 if @condition became true, -ERESTARTSYS if it was
 550  * interrupted by a signal, or -ETIME if the timeout elapsed.
 551  */
 552 #define wait_event_interruptible_hrtimeout(wq, condition, timeout)              \
 553 ({                                                                              \
 554         long __ret = 0;                                                         \
 555         might_sleep();                                                          \
 556         if (!(condition))                                                       \
 557                 __ret = __wait_event_hrtimeout(wq, condition, timeout,          \
 558                                                TASK_INTERRUPTIBLE);             \
 559         __ret;                                                                  \
 560 })
 561
 562 #define __wait_event_interruptible_exclusive(wq, condition)                     \
 563         ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 1, 0,                  \
 564                       schedule())
 565
 566 #define wait_event_interruptible_exclusive(wq, condition)                       \
 567 ({                                                                              \
 568         int __ret = 0;                                                          \
 569         might_sleep();                                                          \
 570         if (!(condition))                                                       \
 571                 __ret = __wait_event_interruptible_exclusive(wq, condition);    \
 572         __ret;                                                                  \
 573 })
 574
 575 #define __wait_event_killable_exclusive(wq, condition)                          \
 576         ___wait_event(wq, condition, TASK_KILLABLE, 1, 0,                       \
 577                       schedule())
 578
 579 #define wait_event_killable_exclusive(wq, condition)                            \
 580 ({                                                                              \
 581         int __ret = 0;                                                          \
 582         might_sleep();                                                          \
 583         if (!(condition))                                                       \
 584                 __ret = __wait_event_killable_exclusive(wq, condition);         \
 585         __ret;                                                                  \
 586 })
 587
 588
 589 #define __wait_event_freezable_exclusive(wq, condition)                         \
 590         ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 1, 0,                  \
 591                         schedule(); try_to_freeze())
 592
 593 #define wait_event_freezable_exclusive(wq, condition)                           \
 594 ({                                                                              \
 595         int __ret = 0;                                                          \
 596         might_sleep();                                                          \
 597         if (!(condition))                                                       \
 598                 __ret = __wait_event_freezable_exclusive(wq, condition);        \
 599         __ret;                                                                  \
 600 })
 601
 602 extern int do_wait_intr(wait_queue_head_t *, wait_queue_entry_t *);
 603 extern int do_wait_intr_irq(wait_queue_head_t *, wait_queue_entry_t *);
 604
 605 #define __wait_event_interruptible_locked(wq, condition, exclusive, fn)         \
 606 ({                                                                              \
 607         int __ret;                                                              \
 608         DEFINE_WAIT(__wait);                                                    \
 609         if (exclusive)                                                          \
 610                 __wait.flags |= WQ_FLAG_EXCLUSIVE;                              \
 611         do {                                                                    \
 612                 __ret = fn(&(wq), &__wait);                                     \
 613                 if (__ret)                                                      \
 614                         break;                                                  \
 615         } while (!(condition));                                                 \
 616         __remove_wait_queue(&(wq), &__wait);                                    \
 617         __set_current_state(TASK_RUNNING);                                      \
 618         __ret;                                                                  \
 619 })
 620
 621
 622 /**
 623  * wait_event_interruptible_locked - sleep until a condition gets true
 624  * @wq: the waitqueue to wait on
 625  * @condition: a C expression for the event to wait for
 626  *
 627  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 628  * @condition evaluates to true or a signal is received.
 629  * The @condition is checked each time the waitqueue @wq is woken up.
 630  *
 631  * It must be called with wq.lock being held.  This spinlock is
 632  * unlocked while sleeping but @condition testing is done while lock
 633  * is held and when this macro exits the lock is held.
 634  *
 635  * The lock is locked/unlocked using spin_lock()/spin_unlock()
 636  * functions which must match the way they are locked/unlocked outside
 637  * of this macro.
 638  *
 639  * wake_up_locked() has to be called after changing any variable that could
 640  * change the result of the wait condition.
 641  *
 642  * The function will return -ERESTARTSYS if it was interrupted by a
 643  * signal and 0 if @condition evaluated to true.
 644  */
 645 #define wait_event_interruptible_locked(wq, condition)                          \
 646         ((condition)                                                            \
 647          ? 0 : __wait_event_interruptible_locked(wq, condition, 0, do_wait_intr))
 648
 649 /**
 650  * wait_event_interruptible_locked_irq - sleep until a condition gets true
 651  * @wq: the waitqueue to wait on
 652  * @condition: a C expression for the event to wait for
 653  *
 654  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 655  * @condition evaluates to true or a signal is received.
 656  * The @condition is checked each time the waitqueue @wq is woken up.
 657  *
 658  * It must be called with wq.lock being held.  This spinlock is
 659  * unlocked while sleeping but @condition testing is done while lock
 660  * is held and when this macro exits the lock is held.
 661  *
 662  * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq()
 663  * functions which must match the way they are locked/unlocked outside
 664  * of this macro.
 665  *
 666  * wake_up_locked() has to be called after changing any variable that could
 667  * change the result of the wait condition.
 668  *
 669  * The function will return -ERESTARTSYS if it was interrupted by a
 670  * signal and 0 if @condition evaluated to true.
 671  */
 672 #define wait_event_interruptible_locked_irq(wq, condition)                      \
 673         ((condition)                                                            \
 674          ? 0 : __wait_event_interruptible_locked(wq, condition, 0, do_wait_intr_irq))
 675
 676 /**
 677  * wait_event_interruptible_exclusive_locked - sleep exclusively until a condition gets true
 678  * @wq: the waitqueue to wait on
 679  * @condition: a C expression for the event to wait for
 680  *
 681  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 682  * @condition evaluates to true or a signal is received.
 683  * The @condition is checked each time the waitqueue @wq is woken up.
 684  *
 685  * It must be called with wq.lock being held.  This spinlock is
 686  * unlocked while sleeping but @condition testing is done while lock
 687  * is held and when this macro exits the lock is held.
 688  *
 689  * The lock is locked/unlocked using spin_lock()/spin_unlock()
 690  * functions which must match the way they are locked/unlocked outside
 691  * of this macro.
 692  *
 693  * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
 694  * set thus when other process waits process on the list if this
 695  * process is awaken further processes are not considered.
 696  *
 697  * wake_up_locked() has to be called after changing any variable that could
 698  * change the result of the wait condition.
 699  *
 700  * The function will return -ERESTARTSYS if it was interrupted by a
 701  * signal and 0 if @condition evaluated to true.
 702  */
 703 #define wait_event_interruptible_exclusive_locked(wq, condition)                \
 704         ((condition)                                                            \
 705          ? 0 : __wait_event_interruptible_locked(wq, condition, 1, do_wait_intr))
 706
 707 /**
 708  * wait_event_interruptible_exclusive_locked_irq - sleep until a condition gets true
 709  * @wq: the waitqueue to wait on
 710  * @condition: a C expression for the event to wait for
 711  *
 712  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 713  * @condition evaluates to true or a signal is received.
 714  * The @condition is checked each time the waitqueue @wq is woken up.
 715  *
 716  * It must be called with wq.lock being held.  This spinlock is
 717  * unlocked while sleeping but @condition testing is done while lock
 718  * is held and when this macro exits the lock is held.
 719  *
 720  * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq()
 721  * functions which must match the way they are locked/unlocked outside
 722  * of this macro.
 723  *
 724  * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
 725  * set thus when other process waits process on the list if this
 726  * process is awaken further processes are not considered.
 727  *
 728  * wake_up_locked() has to be called after changing any variable that could
 729  * change the result of the wait condition.
 730  *
 731  * The function will return -ERESTARTSYS if it was interrupted by a
 732  * signal and 0 if @condition evaluated to true.
 733  */
 734 #define wait_event_interruptible_exclusive_locked_irq(wq, condition)            \
 735         ((condition)                                                            \
 736          ? 0 : __wait_event_interruptible_locked(wq, condition, 1, do_wait_intr_irq))
 737
 738
 739 #define __wait_event_killable(wq, condition)                                    \
 740         ___wait_event(wq, condition, TASK_KILLABLE, 0, 0, schedule())
 741
 742 /**
 743  * wait_event_killable - sleep until a condition gets true
 744  * @wq_head: the waitqueue to wait on
 745  * @condition: a C expression for the event to wait for
 746  *
 747  * The process is put to sleep (TASK_KILLABLE) until the
 748  * @condition evaluates to true or a signal is received.
 749  * The @condition is checked each time the waitqueue @wq_head is woken up.
 750  *
 751  * wake_up() has to be called after changing any variable that could
 752  * change the result of the wait condition.
 753  *
 754  * The function will return -ERESTARTSYS if it was interrupted by a
 755  * signal and 0 if @condition evaluated to true.
 756  */
 757 #define wait_event_killable(wq_head, condition)                                 \
 758 ({                                                                              \
 759         int __ret = 0;                                                          \
 760         might_sleep();                                                          \
 761         if (!(condition))                                                       \
 762                 __ret = __wait_event_killable(wq_head, condition);              \
 763         __ret;                                                                  \
 764 })
 765
 766 #define __wait_event_killable_timeout(wq_head, condition, timeout)              \
 767         ___wait_event(wq_head, ___wait_cond_timeout(condition),                 \
 768                       TASK_KILLABLE, 0, timeout,                                \
 769                       __ret = schedule_timeout(__ret))
 770
 771 /**
 772  * wait_event_killable_timeout - sleep until a condition gets true or a timeout elapses
 773  * @wq_head: the waitqueue to wait on
 774  * @condition: a C expression for the event to wait for
 775  * @timeout: timeout, in jiffies
 776  *
 777  * The process is put to sleep (TASK_KILLABLE) until the
 778  * @condition evaluates to true or a kill signal is received.
 779  * The @condition is checked each time the waitqueue @wq_head is woken up.
 780  *
 781  * wake_up() has to be called after changing any variable that could
 782  * change the result of the wait condition.
 783  *
 784  * Returns:
 785  * 0 if the @condition evaluated to %false after the @timeout elapsed,
 786  * 1 if the @condition evaluated to %true after the @timeout elapsed,
 787  * the remaining jiffies (at least 1) if the @condition evaluated
 788  * to %true before the @timeout elapsed, or -%ERESTARTSYS if it was
 789  * interrupted by a kill signal.
 790  *
 791  * Only kill signals interrupt this process.
 792  */
 793 #define wait_event_killable_timeout(wq_head, condition, timeout)                \
 794 ({                                                                              \
 795         long __ret = timeout;                                                   \
 796         might_sleep();                                                          \
 797         if (!___wait_cond_timeout(condition))                                   \
 798                 __ret = __wait_event_killable_timeout(wq_head,                  \
 799                                                 condition, timeout);            \
 800         __ret;                                                                  \
 801 })
 802
 803
 804 #define __wait_event_lock_irq(wq_head, condition, lock, cmd)                    \
 805         (void)___wait_event(wq_head, condition, TASK_UNINTERRUPTIBLE, 0, 0,     \
 806                             spin_unlock_irq(&lock);                             \
 807                             cmd;                                                \
 808                             schedule();                                         \
 809                             spin_lock_irq(&lock))
 810
 811 /**
 812  * wait_event_lock_irq_cmd - sleep until a condition gets true. The
 813  *                           condition is checked under the lock. This
 814  *                           is expected to be called with the lock
 815  *                           taken.
 816  * @wq_head: the waitqueue to wait on
 817  * @condition: a C expression for the event to wait for
 818  * @lock: a locked spinlock_t, which will be released before cmd
 819  *        and schedule() and reacquired afterwards.
 820  * @cmd: a command which is invoked outside the critical section before
 821  *       sleep
 822  *
 823  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 824  * @condition evaluates to true. The @condition is checked each time
 825  * the waitqueue @wq_head is woken up.
 826  *
 827  * wake_up() has to be called after changing any variable that could
 828  * change the result of the wait condition.
 829  *
 830  * This is supposed to be called while holding the lock. The lock is
 831  * dropped before invoking the cmd and going to sleep and is reacquired
 832  * afterwards.
 833  */
 834 #define wait_event_lock_irq_cmd(wq_head, condition, lock, cmd)                  \
 835 do {                                                                            \
 836         if (condition)                                                          \
 837                 break;                                                          \
 838         __wait_event_lock_irq(wq_head, condition, lock, cmd);                   \
 839 } while (0)
 840
 841 /**
 842  * wait_event_lock_irq - sleep until a condition gets true. The
 843  *                       condition is checked under the lock. This
 844  *                       is expected to be called with the lock
 845  *                       taken.
 846  * @wq_head: the waitqueue to wait on
 847  * @condition: a C expression for the event to wait for
 848  * @lock: a locked spinlock_t, which will be released before schedule()
 849  *        and reacquired afterwards.
 850  *
 851  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 852  * @condition evaluates to true. The @condition is checked each time
 853  * the waitqueue @wq_head is woken up.
 854  *
 855  * wake_up() has to be called after changing any variable that could
 856  * change the result of the wait condition.
 857  *
 858  * This is supposed to be called while holding the lock. The lock is
 859  * dropped before going to sleep and is reacquired afterwards.
 860  */
 861 #define wait_event_lock_irq(wq_head, condition, lock)                           \
 862 do {                                                                            \
 863         if (condition)                                                          \
 864                 break;                                                          \
 865         __wait_event_lock_irq(wq_head, condition, lock, );                      \
 866 } while (0)
 867
 868
 869 #define __wait_event_interruptible_lock_irq(wq_head, condition, lock, cmd)      \
 870         ___wait_event(wq_head, condition, TASK_INTERRUPTIBLE, 0, 0,             \
 871                       spin_unlock_irq(&lock);                                   \
 872                       cmd;                                                      \
 873                       schedule();                                               \
 874                       spin_lock_irq(&lock))
 875
 876 /**
 877  * wait_event_interruptible_lock_irq_cmd - sleep until a condition gets true.
 878  *              The condition is checked under the lock. This is expected to
 879  *              be called with the lock taken.
 880  * @wq_head: the waitqueue to wait on
 881  * @condition: a C expression for the event to wait for
 882  * @lock: a locked spinlock_t, which will be released before cmd and
 883  *        schedule() and reacquired afterwards.
 884  * @cmd: a command which is invoked outside the critical section before
 885  *       sleep
 886  *
 887  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 888  * @condition evaluates to true or a signal is received. The @condition is
 889  * checked each time the waitqueue @wq_head is woken up.
 890  *
 891  * wake_up() has to be called after changing any variable that could
 892  * change the result of the wait condition.
 893  *
 894  * This is supposed to be called while holding the lock. The lock is
 895  * dropped before invoking the cmd and going to sleep and is reacquired
 896  * afterwards.
 897  *
 898  * The macro will return -ERESTARTSYS if it was interrupted by a signal
 899  * and 0 if @condition evaluated to true.
 900  */
 901 #define wait_event_interruptible_lock_irq_cmd(wq_head, condition, lock, cmd)    \
 902 ({                                                                              \
 903         int __ret = 0;                                                          \
 904         if (!(condition))                                                       \
 905                 __ret = __wait_event_interruptible_lock_irq(wq_head,            \
 906                                                 condition, lock, cmd);          \
 907         __ret;                                                                  \
 908 })
 909
 910 /**
 911  * wait_event_interruptible_lock_irq - sleep until a condition gets true.
 912  *              The condition is checked under the lock. This is expected
 913  *              to be called with the lock taken.
 914  * @wq_head: the waitqueue to wait on
 915  * @condition: a C expression for the event to wait for
 916  * @lock: a locked spinlock_t, which will be released before schedule()
 917  *        and reacquired afterwards.
 918  *
 919  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 920  * @condition evaluates to true or signal is received. The @condition is
 921  * checked each time the waitqueue @wq_head is woken up.
 922  *
 923  * wake_up() has to be called after changing any variable that could
 924  * change the result of the wait condition.
 925  *
 926  * This is supposed to be called while holding the lock. The lock is
 927  * dropped before going to sleep and is reacquired afterwards.
 928  *
 929  * The macro will return -ERESTARTSYS if it was interrupted by a signal
 930  * and 0 if @condition evaluated to true.
 931  */
 932 #define wait_event_interruptible_lock_irq(wq_head, condition, lock)             \
 933 ({                                                                              \
 934         int __ret = 0;                                                          \
 935         if (!(condition))                                                       \
 936                 __ret = __wait_event_interruptible_lock_irq(wq_head,            \
 937                                                 condition, lock,);              \
 938         __ret;                                                                  \
 939 })
 940
 941 #define __wait_event_interruptible_lock_irq_timeout(wq_head, condition,         \
 942                                                     lock, timeout)              \
 943         ___wait_event(wq_head, ___wait_cond_timeout(condition),                 \
 944                       TASK_INTERRUPTIBLE, 0, timeout,                           \
 945                       spin_unlock_irq(&lock);                                   \
 946                       __ret = schedule_timeout(__ret);                          \
 947                       spin_lock_irq(&lock));
 948
 949 /**
 950  * wait_event_interruptible_lock_irq_timeout - sleep until a condition gets
 951  *              true or a timeout elapses. The condition is checked under
 952  *              the lock. This is expected to be called with the lock taken.
 953  * @wq_head: the waitqueue to wait on
 954  * @condition: a C expression for the event to wait for
 955  * @lock: a locked spinlock_t, which will be released before schedule()
 956  *        and reacquired afterwards.
 957  * @timeout: timeout, in jiffies
 958  *
 959  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 960  * @condition evaluates to true or signal is received. The @condition is
 961  * checked each time the waitqueue @wq_head is woken up.
 962  *
 963  * wake_up() has to be called after changing any variable that could
 964  * change the result of the wait condition.
 965  *
 966  * This is supposed to be called while holding the lock. The lock is
 967  * dropped before going to sleep and is reacquired afterwards.
 968  *
 969  * The function returns 0 if the @timeout elapsed, -ERESTARTSYS if it
 970  * was interrupted by a signal, and the remaining jiffies otherwise
 971  * if the condition evaluated to true before the timeout elapsed.
 972  */
 973 #define wait_event_interruptible_lock_irq_timeout(wq_head, condition, lock,     \
 974                                                   timeout)                      \
 975 ({                                                                              \
 976         long __ret = timeout;                                                   \
 977         if (!___wait_cond_timeout(condition))                                   \
 978                 __ret = __wait_event_interruptible_lock_irq_timeout(            \
 979                                         wq_head, condition, lock, timeout);     \
 980         __ret;                                                                  \
 981 })
 982
 983 /*
 984  * Waitqueues which are removed from the waitqueue_head at wakeup time
 985  */
 986 void prepare_to_wait(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry, int state);
 987 void prepare_to_wait_exclusive(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry, int state);
 988 long prepare_to_wait_event(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry, int state);
 989 void finish_wait(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry);
 990 long wait_woken(struct wait_queue_entry *wq_entry, unsigned mode, long timeout);
 991 int woken_wake_function(struct wait_queue_entry *wq_entry, unsigned mode, int sync, void *key);
 992 int autoremove_wake_function(struct wait_queue_entry *wq_entry, unsigned mode, int sync, void *key);
 993
 994 #define DEFINE_WAIT_FUNC(name, function)                                        \
 995         struct wait_queue_entry name = {                                        \
 996                 .private        = current,                                      \
 997                 .func           = function,                                     \
 998                 .entry          = LIST_HEAD_INIT((name).entry),                 \
 999         }
1000
1001 #define DEFINE_WAIT(name) DEFINE_WAIT_FUNC(name, autoremove_wake_function)
1002
1003 #define init_wait(wait)                                                         \
1004         do {                                                                    \
1005                 (wait)->private = current;                                      \
1006                 (wait)->func = autoremove_wake_function;                        \
1007                 INIT_LIST_HEAD(&(wait)->entry);                                 \
1008                 (wait)->flags = 0;                                              \
1009         } while (0)
1010
1011 #endif /* _LINUX_WAIT_H */