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 #define WQ_FLAG_BOOKMARK        0x04
  22
  23 /*
  24  * A single wait-queue entry structure:
  25  */
  26 struct wait_queue_entry {
  27         unsigned int            flags;
  28         void                    *private;
  29         wait_queue_func_t       func;
  30         struct list_head        entry;
  31 };
  32
  33 struct wait_queue_head {
  34         spinlock_t              lock;
  35         struct list_head        head;
  36 };
  37 typedef struct wait_queue_head wait_queue_head_t;
  38
  39 struct task_struct;
  40
  41 /*
  42  * Macros for declaration and initialisaton of the datatypes
  43  */
  44
  45 #define __WAITQUEUE_INITIALIZER(name, tsk) {                                    \
  46         .private        = tsk,                                                  \
  47         .func           = default_wake_function,                                \
  48         .entry          = { NULL, NULL } }
  49
  50 #define DECLARE_WAITQUEUE(name, tsk)                                            \
  51         struct wait_queue_entry name = __WAITQUEUE_INITIALIZER(name, tsk)
  52
  53 #define __WAIT_QUEUE_HEAD_INITIALIZER(name) {                                   \
  54         .lock           = __SPIN_LOCK_UNLOCKED(name.lock),                      \
  55         .head           = { &(name).head, &(name).head } }
  56
  57 #define DECLARE_WAIT_QUEUE_HEAD(name) \
  58         struct wait_queue_head name = __WAIT_QUEUE_HEAD_INITIALIZER(name)
  59
  60 extern void __init_waitqueue_head(struct wait_queue_head *wq_head, const char *name, struct lock_class_key *);
  61
  62 #define init_waitqueue_head(wq_head)                                            \
  63         do {                                                                    \
  64                 static struct lock_class_key __key;                             \
  65                                                                                 \
  66                 __init_waitqueue_head((wq_head), #wq_head, &__key);             \
  67         } while (0)
  68
  69 #ifdef CONFIG_LOCKDEP
  70 # define __WAIT_QUEUE_HEAD_INIT_ONSTACK(name) \
  71         ({ init_waitqueue_head(&name); name; })
  72 # define DECLARE_WAIT_QUEUE_HEAD_ONSTACK(name) \
  73         struct wait_queue_head name = __WAIT_QUEUE_HEAD_INIT_ONSTACK(name)
  74 #else
  75 # define DECLARE_WAIT_QUEUE_HEAD_ONSTACK(name) DECLARE_WAIT_QUEUE_HEAD(name)
  76 #endif
  77
  78 static inline void init_waitqueue_entry(struct wait_queue_entry *wq_entry, struct task_struct *p)
  79 {
  80         wq_entry->flags         = 0;
  81         wq_entry->private       = p;
  82         wq_entry->func          = default_wake_function;
  83 }
  84
  85 static inline void
  86 init_waitqueue_func_entry(struct wait_queue_entry *wq_entry, wait_queue_func_t func)
  87 {
  88         wq_entry->flags         = 0;
  89         wq_entry->private       = NULL;
  90         wq_entry->func          = func;
  91 }
  92
  93 /**
  94  * waitqueue_active -- locklessly test for waiters on the queue
  95  * @wq_head: the waitqueue to test for waiters
  96  *
  97  * returns true if the wait list is not empty
  98  *
  99  * NOTE: this function is lockless and requires care, incorrect usage _will_
 100  * lead to sporadic and non-obvious failure.
 101  *
 102  * Use either while holding wait_queue_head::lock or when used for wakeups
 103  * with an extra smp_mb() like:
 104  *
 105  *      CPU0 - waker                    CPU1 - waiter
 106  *
 107  *                                      for (;;) {
 108  *      @cond = true;                     prepare_to_wait(&wq_head, &wait, state);
 109  *      smp_mb();                         // smp_mb() from set_current_state()
 110  *      if (waitqueue_active(wq_head))         if (@cond)
 111  *        wake_up(wq_head);                      break;
 112  *                                        schedule();
 113  *                                      }
 114  *                                      finish_wait(&wq_head, &wait);
 115  *
 116  * Because without the explicit smp_mb() it's possible for the
 117  * waitqueue_active() load to get hoisted over the @cond store such that we'll
 118  * observe an empty wait list while the waiter might not observe @cond.
 119  *
 120  * Also note that this 'optimization' trades a spin_lock() for an smp_mb(),
 121  * which (when the lock is uncontended) are of roughly equal cost.
 122  */
 123 static inline int waitqueue_active(struct wait_queue_head *wq_head)
 124 {
 125         return !list_empty(&wq_head->head);
 126 }
 127
 128 /**
 129  * wq_has_sleeper - check if there are any waiting processes
 130  * @wq_head: wait queue head
 131  *
 132  * Returns true if wq_head has waiting processes
 133  *
 134  * Please refer to the comment for waitqueue_active.
 135  */
 136 static inline bool wq_has_sleeper(struct wait_queue_head *wq_head)
 137 {
 138         /*
 139          * We need to be sure we are in sync with the
 140          * add_wait_queue modifications to the wait queue.
 141          *
 142          * This memory barrier should be paired with one on the
 143          * waiting side.
 144          */
 145         smp_mb();
 146         return waitqueue_active(wq_head);
 147 }
 148
 149 extern void add_wait_queue(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry);
 150 extern void add_wait_queue_exclusive(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry);
 151 extern void remove_wait_queue(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry);
 152
 153 static inline void __add_wait_queue(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry)
 154 {
 155         list_add(&wq_entry->entry, &wq_head->head);
 156 }
 157
 158 /*
 159  * Used for wake-one threads:
 160  */
 161 static inline void
 162 __add_wait_queue_exclusive(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry)
 163 {
 164         wq_entry->flags |= WQ_FLAG_EXCLUSIVE;
 165         __add_wait_queue(wq_head, wq_entry);
 166 }
 167
 168 static inline void __add_wait_queue_entry_tail(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry)
 169 {
 170         list_add_tail(&wq_entry->entry, &wq_head->head);
 171 }
 172
 173 static inline void
 174 __add_wait_queue_entry_tail_exclusive(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry)
 175 {
 176         wq_entry->flags |= WQ_FLAG_EXCLUSIVE;
 177         __add_wait_queue_entry_tail(wq_head, wq_entry);
 178 }
 179
 180 static inline void
 181 __remove_wait_queue(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry)
 182 {
 183         list_del(&wq_entry->entry);
 184 }
 185
 186 void __wake_up(struct wait_queue_head *wq_head, unsigned int mode, int nr, void *key);
 187 void __wake_up_locked_key(struct wait_queue_head *wq_head, unsigned int mode, void *key);
 188 void __wake_up_locked_key_bookmark(struct wait_queue_head *wq_head,
 189                 unsigned int mode, void *key, wait_queue_entry_t *bookmark);
 190 void __wake_up_sync_key(struct wait_queue_head *wq_head, unsigned int mode, int nr, void *key);
 191 void __wake_up_locked(struct wait_queue_head *wq_head, unsigned int mode, int nr);
 192 void __wake_up_sync(struct wait_queue_head *wq_head, unsigned int mode, int nr);
 193
 194 #define wake_up(x)                      __wake_up(x, TASK_NORMAL, 1, NULL)
 195 #define wake_up_nr(x, nr)               __wake_up(x, TASK_NORMAL, nr, NULL)
 196 #define wake_up_all(x)                  __wake_up(x, TASK_NORMAL, 0, NULL)
 197 #define wake_up_locked(x)               __wake_up_locked((x), TASK_NORMAL, 1)
 198 #define wake_up_all_locked(x)           __wake_up_locked((x), TASK_NORMAL, 0)
 199
 200 #define wake_up_interruptible(x)        __wake_up(x, TASK_INTERRUPTIBLE, 1, NULL)
 201 #define wake_up_interruptible_nr(x, nr) __wake_up(x, TASK_INTERRUPTIBLE, nr, NULL)
 202 #define wake_up_interruptible_all(x)    __wake_up(x, TASK_INTERRUPTIBLE, 0, NULL)
 203 #define wake_up_interruptible_sync(x)   __wake_up_sync((x), TASK_INTERRUPTIBLE, 1)
 204
 205 /*
 206  * Wakeup macros to be used to report events to the targets.
 207  */
 208 #define wake_up_poll(x, m)                                                      \
 209         __wake_up(x, TASK_NORMAL, 1, (void *) (m))
 210 #define wake_up_locked_poll(x, m)                                               \
 211         __wake_up_locked_key((x), TASK_NORMAL, (void *) (m))
 212 #define wake_up_interruptible_poll(x, m)                                        \
 213         __wake_up(x, TASK_INTERRUPTIBLE, 1, (void *) (m))
 214 #define wake_up_interruptible_sync_poll(x, m)                                   \
 215         __wake_up_sync_key((x), TASK_INTERRUPTIBLE, 1, (void *) (m))
 216
 217 #define ___wait_cond_timeout(condition)                                         \
 218 ({                                                                              \
 219         bool __cond = (condition);                                              \
 220         if (__cond && !__ret)                                                   \
 221                 __ret = 1;                                                      \
 222         __cond || !__ret;                                                       \
 223 })
 224
 225 #define ___wait_is_interruptible(state)                                         \
 226         (!__builtin_constant_p(state) ||                                        \
 227                 state == TASK_INTERRUPTIBLE || state == TASK_KILLABLE)          \
 228
 229 extern void init_wait_entry(struct wait_queue_entry *wq_entry, int flags);
 230
 231 /*
 232  * The below macro ___wait_event() has an explicit shadow of the __ret
 233  * variable when used from the wait_event_*() macros.
 234  *
 235  * This is so that both can use the ___wait_cond_timeout() construct
 236  * to wrap the condition.
 237  *
 238  * The type inconsistency of the wait_event_*() __ret variable is also
 239  * on purpose; we use long where we can return timeout values and int
 240  * otherwise.
 241  */
 242
 243 #define ___wait_event(wq_head, condition, state, exclusive, ret, cmd)           \
 244 ({                                                                              \
 245         __label__ __out;                                                        \
 246         struct wait_queue_entry __wq_entry;                                     \
 247         long __ret = ret;       /* explicit shadow */                           \
 248                                                                                 \
 249         init_wait_entry(&__wq_entry, exclusive ? WQ_FLAG_EXCLUSIVE : 0);        \
 250         for (;;) {                                                              \
 251                 long __int = prepare_to_wait_event(&wq_head, &__wq_entry, state);\
 252                                                                                 \
 253                 if (condition)                                                  \
 254                         break;                                                  \
 255                                                                                 \
 256                 if (___wait_is_interruptible(state) && __int) {                 \
 257                         __ret = __int;                                          \
 258                         goto __out;                                             \
 259                 }                                                               \
 260                                                                                 \
 261                 cmd;                                                            \
 262         }                                                                       \
 263         finish_wait(&wq_head, &__wq_entry);                                     \
 264 __out:  __ret;                                                                  \
 265 })
 266
 267 #define __wait_event(wq_head, condition)                                        \
 268         (void)___wait_event(wq_head, condition, TASK_UNINTERRUPTIBLE, 0, 0,     \
 269                             schedule())
 270
 271 /**
 272  * wait_event - sleep until a condition gets true
 273  * @wq_head: the waitqueue to wait on
 274  * @condition: a C expression for the event to wait for
 275  *
 276  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 277  * @condition evaluates to true. The @condition is checked each time
 278  * the waitqueue @wq_head is woken up.
 279  *
 280  * wake_up() has to be called after changing any variable that could
 281  * change the result of the wait condition.
 282  */
 283 #define wait_event(wq_head, condition)                                          \
 284 do {                                                                            \
 285         might_sleep();                                                          \
 286         if (condition)                                                          \
 287                 break;                                                          \
 288         __wait_event(wq_head, condition);                                       \
 289 } while (0)
 290
 291 #define __io_wait_event(wq_head, condition)                                     \
 292         (void)___wait_event(wq_head, condition, TASK_UNINTERRUPTIBLE, 0, 0,     \
 293                             io_schedule())
 294
 295 /*
 296  * io_wait_event() -- like wait_event() but with io_schedule()
 297  */
 298 #define io_wait_event(wq_head, condition)                                       \
 299 do {                                                                            \
 300         might_sleep();                                                          \
 301         if (condition)                                                          \
 302                 break;                                                          \
 303         __io_wait_event(wq_head, condition);                                    \
 304 } while (0)
 305
 306 #define __wait_event_freezable(wq_head, condition)                              \
 307         ___wait_event(wq_head, condition, TASK_INTERRUPTIBLE, 0, 0,             \
 308                             schedule(); try_to_freeze())
 309
 310 /**
 311  * wait_event_freezable - sleep (or freeze) until a condition gets true
 312  * @wq_head: the waitqueue to wait on
 313  * @condition: a C expression for the event to wait for
 314  *
 315  * The process is put to sleep (TASK_INTERRUPTIBLE -- so as not to contribute
 316  * to system load) until the @condition evaluates to true. The
 317  * @condition is checked each time the waitqueue @wq_head is woken up.
 318  *
 319  * wake_up() has to be called after changing any variable that could
 320  * change the result of the wait condition.
 321  */
 322 #define wait_event_freezable(wq_head, condition)                                \
 323 ({                                                                              \
 324         int __ret = 0;                                                          \
 325         might_sleep();                                                          \
 326         if (!(condition))                                                       \
 327                 __ret = __wait_event_freezable(wq_head, condition);             \
 328         __ret;                                                                  \
 329 })
 330
 331 #define __wait_event_timeout(wq_head, condition, timeout)                       \
 332         ___wait_event(wq_head, ___wait_cond_timeout(condition),                 \
 333                       TASK_UNINTERRUPTIBLE, 0, timeout,                         \
 334                       __ret = schedule_timeout(__ret))
 335
 336 /**
 337  * wait_event_timeout - sleep until a condition gets true or a timeout elapses
 338  * @wq_head: the waitqueue to wait on
 339  * @condition: a C expression for the event to wait for
 340  * @timeout: timeout, in jiffies
 341  *
 342  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 343  * @condition evaluates to true. The @condition is checked each time
 344  * the waitqueue @wq_head is woken up.
 345  *
 346  * wake_up() has to be called after changing any variable that could
 347  * change the result of the wait condition.
 348  *
 349  * Returns:
 350  * 0 if the @condition evaluated to %false after the @timeout elapsed,
 351  * 1 if the @condition evaluated to %true after the @timeout elapsed,
 352  * or the remaining jiffies (at least 1) if the @condition evaluated
 353  * to %true before the @timeout elapsed.
 354  */
 355 #define wait_event_timeout(wq_head, condition, timeout)                         \
 356 ({                                                                              \
 357         long __ret = timeout;                                                   \
 358         might_sleep();                                                          \
 359         if (!___wait_cond_timeout(condition))                                   \
 360                 __ret = __wait_event_timeout(wq_head, condition, timeout);      \
 361         __ret;                                                                  \
 362 })
 363
 364 #define __wait_event_freezable_timeout(wq_head, condition, timeout)             \
 365         ___wait_event(wq_head, ___wait_cond_timeout(condition),                 \
 366                       TASK_INTERRUPTIBLE, 0, timeout,                           \
 367                       __ret = schedule_timeout(__ret); try_to_freeze())
 368
 369 /*
 370  * like wait_event_timeout() -- except it uses TASK_INTERRUPTIBLE to avoid
 371  * increasing load and is freezable.
 372  */
 373 #define wait_event_freezable_timeout(wq_head, condition, timeout)               \
 374 ({                                                                              \
 375         long __ret = timeout;                                                   \
 376         might_sleep();                                                          \
 377         if (!___wait_cond_timeout(condition))                                   \
 378                 __ret = __wait_event_freezable_timeout(wq_head, condition, timeout); \
 379         __ret;                                                                  \
 380 })
 381
 382 #define __wait_event_exclusive_cmd(wq_head, condition, cmd1, cmd2)              \
 383         (void)___wait_event(wq_head, condition, TASK_UNINTERRUPTIBLE, 1, 0,     \
 384                             cmd1; schedule(); cmd2)
 385 /*
 386  * Just like wait_event_cmd(), except it sets exclusive flag
 387  */
 388 #define wait_event_exclusive_cmd(wq_head, condition, cmd1, cmd2)                \
 389 do {                                                                            \
 390         if (condition)                                                          \
 391                 break;                                                          \
 392         __wait_event_exclusive_cmd(wq_head, condition, cmd1, cmd2);             \
 393 } while (0)
 394
 395 #define __wait_event_cmd(wq_head, condition, cmd1, cmd2)                        \
 396         (void)___wait_event(wq_head, condition, TASK_UNINTERRUPTIBLE, 0, 0,     \
 397                             cmd1; schedule(); cmd2)
 398
 399 /**
 400  * wait_event_cmd - sleep until a condition gets true
 401  * @wq_head: the waitqueue to wait on
 402  * @condition: a C expression for the event to wait for
 403  * @cmd1: the command will be executed before sleep
 404  * @cmd2: the command will be executed after sleep
 405  *
 406  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 407  * @condition evaluates to true. The @condition is checked each time
 408  * the waitqueue @wq_head is woken up.
 409  *
 410  * wake_up() has to be called after changing any variable that could
 411  * change the result of the wait condition.
 412  */
 413 #define wait_event_cmd(wq_head, condition, cmd1, cmd2)                          \
 414 do {                                                                            \
 415         if (condition)                                                          \
 416                 break;                                                          \
 417         __wait_event_cmd(wq_head, condition, cmd1, cmd2);                       \
 418 } while (0)
 419
 420 #define __wait_event_interruptible(wq_head, condition)                          \
 421         ___wait_event(wq_head, condition, TASK_INTERRUPTIBLE, 0, 0,             \
 422                       schedule())
 423
 424 /**
 425  * wait_event_interruptible - sleep until a condition gets true
 426  * @wq_head: the waitqueue to wait on
 427  * @condition: a C expression for the event to wait for
 428  *
 429  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 430  * @condition evaluates to true or a signal is received.
 431  * The @condition is checked each time the waitqueue @wq_head is woken up.
 432  *
 433  * wake_up() has to be called after changing any variable that could
 434  * change the result of the wait condition.
 435  *
 436  * The function will return -ERESTARTSYS if it was interrupted by a
 437  * signal and 0 if @condition evaluated to true.
 438  */
 439 #define wait_event_interruptible(wq_head, condition)                            \
 440 ({                                                                              \
 441         int __ret = 0;                                                          \
 442         might_sleep();                                                          \
 443         if (!(condition))                                                       \
 444                 __ret = __wait_event_interruptible(wq_head, condition);         \
 445         __ret;                                                                  \
 446 })
 447
 448 #define __wait_event_interruptible_timeout(wq_head, condition, timeout)         \
 449         ___wait_event(wq_head, ___wait_cond_timeout(condition),                 \
 450                       TASK_INTERRUPTIBLE, 0, timeout,                           \
 451                       __ret = schedule_timeout(__ret))
 452
 453 /**
 454  * wait_event_interruptible_timeout - sleep until a condition gets true or a timeout elapses
 455  * @wq_head: the waitqueue to wait on
 456  * @condition: a C expression for the event to wait for
 457  * @timeout: timeout, in jiffies
 458  *
 459  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 460  * @condition evaluates to true or a signal is received.
 461  * The @condition is checked each time the waitqueue @wq_head is woken up.
 462  *
 463  * wake_up() has to be called after changing any variable that could
 464  * change the result of the wait condition.
 465  *
 466  * Returns:
 467  * 0 if the @condition evaluated to %false after the @timeout elapsed,
 468  * 1 if the @condition evaluated to %true after the @timeout elapsed,
 469  * the remaining jiffies (at least 1) if the @condition evaluated
 470  * to %true before the @timeout elapsed, or -%ERESTARTSYS if it was
 471  * interrupted by a signal.
 472  */
 473 #define wait_event_interruptible_timeout(wq_head, condition, timeout)           \
 474 ({                                                                              \
 475         long __ret = timeout;                                                   \
 476         might_sleep();                                                          \
 477         if (!___wait_cond_timeout(condition))                                   \
 478                 __ret = __wait_event_interruptible_timeout(wq_head,             \
 479                                                 condition, timeout);            \
 480         __ret;                                                                  \
 481 })
 482
 483 #define __wait_event_hrtimeout(wq_head, condition, timeout, state)              \
 484 ({                                                                              \
 485         int __ret = 0;                                                          \
 486         struct hrtimer_sleeper __t;                                             \
 487                                                                                 \
 488         hrtimer_init_on_stack(&__t.timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);   \
 489         hrtimer_init_sleeper(&__t, current);                                    \
 490         if ((timeout) != KTIME_MAX)                                             \
 491                 hrtimer_start_range_ns(&__t.timer, timeout,                     \
 492                                        current->timer_slack_ns,                 \
 493                                        HRTIMER_MODE_REL);                       \
 494                                                                                 \
 495         __ret = ___wait_event(wq_head, condition, state, 0, 0,                  \
 496                 if (!__t.task) {                                                \
 497                         __ret = -ETIME;                                         \
 498                         break;                                                  \
 499                 }                                                               \
 500                 schedule());                                                    \
 501                                                                                 \
 502         hrtimer_cancel(&__t.timer);                                             \
 503         destroy_hrtimer_on_stack(&__t.timer);                                   \
 504         __ret;                                                                  \
 505 })
 506
 507 /**
 508  * wait_event_hrtimeout - sleep until a condition gets true or a timeout elapses
 509  * @wq_head: the waitqueue to wait on
 510  * @condition: a C expression for the event to wait for
 511  * @timeout: timeout, as a ktime_t
 512  *
 513  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 514  * @condition evaluates to true or a signal is received.
 515  * The @condition is checked each time the waitqueue @wq_head is woken up.
 516  *
 517  * wake_up() has to be called after changing any variable that could
 518  * change the result of the wait condition.
 519  *
 520  * The function returns 0 if @condition became true, or -ETIME if the timeout
 521  * elapsed.
 522  */
 523 #define wait_event_hrtimeout(wq_head, condition, timeout)                       \
 524 ({                                                                              \
 525         int __ret = 0;                                                          \
 526         might_sleep();                                                          \
 527         if (!(condition))                                                       \
 528                 __ret = __wait_event_hrtimeout(wq_head, condition, timeout,     \
 529                                                TASK_UNINTERRUPTIBLE);           \
 530         __ret;                                                                  \
 531 })
 532
 533 /**
 534  * wait_event_interruptible_hrtimeout - sleep until a condition gets true or a timeout elapses
 535  * @wq: the waitqueue to wait on
 536  * @condition: a C expression for the event to wait for
 537  * @timeout: timeout, as a ktime_t
 538  *
 539  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 540  * @condition evaluates to true or a signal is received.
 541  * The @condition is checked each time the waitqueue @wq is woken up.
 542  *
 543  * wake_up() has to be called after changing any variable that could
 544  * change the result of the wait condition.
 545  *
 546  * The function returns 0 if @condition became true, -ERESTARTSYS if it was
 547  * interrupted by a signal, or -ETIME if the timeout elapsed.
 548  */
 549 #define wait_event_interruptible_hrtimeout(wq, condition, timeout)              \
 550 ({                                                                              \
 551         long __ret = 0;                                                         \
 552         might_sleep();                                                          \
 553         if (!(condition))                                                       \
 554                 __ret = __wait_event_hrtimeout(wq, condition, timeout,          \
 555                                                TASK_INTERRUPTIBLE);             \
 556         __ret;                                                                  \
 557 })
 558
 559 #define __wait_event_interruptible_exclusive(wq, condition)                     \
 560         ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 1, 0,                  \
 561                       schedule())
 562
 563 #define wait_event_interruptible_exclusive(wq, condition)                       \
 564 ({                                                                              \
 565         int __ret = 0;                                                          \
 566         might_sleep();                                                          \
 567         if (!(condition))                                                       \
 568                 __ret = __wait_event_interruptible_exclusive(wq, condition);    \
 569         __ret;                                                                  \
 570 })
 571
 572 #define __wait_event_killable_exclusive(wq, condition)                          \
 573         ___wait_event(wq, condition, TASK_KILLABLE, 1, 0,                       \
 574                       schedule())
 575
 576 #define wait_event_killable_exclusive(wq, condition)                            \
 577 ({                                                                              \
 578         int __ret = 0;                                                          \
 579         might_sleep();                                                          \
 580         if (!(condition))                                                       \
 581                 __ret = __wait_event_killable_exclusive(wq, condition);         \
 582         __ret;                                                                  \
 583 })
 584
 585
 586 #define __wait_event_freezable_exclusive(wq, condition)                         \
 587         ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 1, 0,                  \
 588                         schedule(); try_to_freeze())
 589
 590 #define wait_event_freezable_exclusive(wq, condition)                           \
 591 ({                                                                              \
 592         int __ret = 0;                                                          \
 593         might_sleep();                                                          \
 594         if (!(condition))                                                       \
 595                 __ret = __wait_event_freezable_exclusive(wq, condition);        \
 596         __ret;                                                                  \
 597 })
 598
 599 extern int do_wait_intr(wait_queue_head_t *, wait_queue_entry_t *);
 600 extern int do_wait_intr_irq(wait_queue_head_t *, wait_queue_entry_t *);
 601
 602 #define __wait_event_interruptible_locked(wq, condition, exclusive, fn)         \
 603 ({                                                                              \
 604         int __ret;                                                              \
 605         DEFINE_WAIT(__wait);                                                    \
 606         if (exclusive)                                                          \
 607                 __wait.flags |= WQ_FLAG_EXCLUSIVE;                              \
 608         do {                                                                    \
 609                 __ret = fn(&(wq), &__wait);                                     \
 610                 if (__ret)                                                      \
 611                         break;                                                  \
 612         } while (!(condition));                                                 \
 613         __remove_wait_queue(&(wq), &__wait);                                    \
 614         __set_current_state(TASK_RUNNING);                                      \
 615         __ret;                                                                  \
 616 })
 617
 618
 619 /**
 620  * wait_event_interruptible_locked - sleep until a condition gets true
 621  * @wq: the waitqueue to wait on
 622  * @condition: a C expression for the event to wait for
 623  *
 624  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 625  * @condition evaluates to true or a signal is received.
 626  * The @condition is checked each time the waitqueue @wq is woken up.
 627  *
 628  * It must be called with wq.lock being held.  This spinlock is
 629  * unlocked while sleeping but @condition testing is done while lock
 630  * is held and when this macro exits the lock is held.
 631  *
 632  * The lock is locked/unlocked using spin_lock()/spin_unlock()
 633  * functions which must match the way they are locked/unlocked outside
 634  * of this macro.
 635  *
 636  * wake_up_locked() has to be called after changing any variable that could
 637  * change the result of the wait condition.
 638  *
 639  * The function will return -ERESTARTSYS if it was interrupted by a
 640  * signal and 0 if @condition evaluated to true.
 641  */
 642 #define wait_event_interruptible_locked(wq, condition)                          \
 643         ((condition)                                                            \
 644          ? 0 : __wait_event_interruptible_locked(wq, condition, 0, do_wait_intr))
 645
 646 /**
 647  * wait_event_interruptible_locked_irq - 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_irq()/spin_unlock_irq()
 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_irq(wq, condition)                      \
 670         ((condition)                                                            \
 671          ? 0 : __wait_event_interruptible_locked(wq, condition, 0, do_wait_intr_irq))
 672
 673 /**
 674  * wait_event_interruptible_exclusive_locked - sleep exclusively 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()/spin_unlock()
 687  * functions which must match the way they are locked/unlocked outside
 688  * of this macro.
 689  *
 690  * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
 691  * set thus when other process waits process on the list if this
 692  * process is awaken further processes are not considered.
 693  *
 694  * wake_up_locked() has to be called after changing any variable that could
 695  * change the result of the wait condition.
 696  *
 697  * The function will return -ERESTARTSYS if it was interrupted by a
 698  * signal and 0 if @condition evaluated to true.
 699  */
 700 #define wait_event_interruptible_exclusive_locked(wq, condition)                \
 701         ((condition)                                                            \
 702          ? 0 : __wait_event_interruptible_locked(wq, condition, 1, do_wait_intr))
 703
 704 /**
 705  * wait_event_interruptible_exclusive_locked_irq - sleep until a condition gets true
 706  * @wq: the waitqueue to wait on
 707  * @condition: a C expression for the event to wait for
 708  *
 709  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 710  * @condition evaluates to true or a signal is received.
 711  * The @condition is checked each time the waitqueue @wq is woken up.
 712  *
 713  * It must be called with wq.lock being held.  This spinlock is
 714  * unlocked while sleeping but @condition testing is done while lock
 715  * is held and when this macro exits the lock is held.
 716  *
 717  * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq()
 718  * functions which must match the way they are locked/unlocked outside
 719  * of this macro.
 720  *
 721  * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
 722  * set thus when other process waits process on the list if this
 723  * process is awaken further processes are not considered.
 724  *
 725  * wake_up_locked() has to be called after changing any variable that could
 726  * change the result of the wait condition.
 727  *
 728  * The function will return -ERESTARTSYS if it was interrupted by a
 729  * signal and 0 if @condition evaluated to true.
 730  */
 731 #define wait_event_interruptible_exclusive_locked_irq(wq, condition)            \
 732         ((condition)                                                            \
 733          ? 0 : __wait_event_interruptible_locked(wq, condition, 1, do_wait_intr_irq))
 734
 735
 736 #define __wait_event_killable(wq, condition)                                    \
 737         ___wait_event(wq, condition, TASK_KILLABLE, 0, 0, schedule())
 738
 739 /**
 740  * wait_event_killable - sleep until a condition gets true
 741  * @wq_head: the waitqueue to wait on
 742  * @condition: a C expression for the event to wait for
 743  *
 744  * The process is put to sleep (TASK_KILLABLE) until the
 745  * @condition evaluates to true or a signal is received.
 746  * The @condition is checked each time the waitqueue @wq_head is woken up.
 747  *
 748  * wake_up() has to be called after changing any variable that could
 749  * change the result of the wait condition.
 750  *
 751  * The function will return -ERESTARTSYS if it was interrupted by a
 752  * signal and 0 if @condition evaluated to true.
 753  */
 754 #define wait_event_killable(wq_head, condition)                                 \
 755 ({                                                                              \
 756         int __ret = 0;                                                          \
 757         might_sleep();                                                          \
 758         if (!(condition))                                                       \
 759                 __ret = __wait_event_killable(wq_head, condition);              \
 760         __ret;                                                                  \
 761 })
 762
 763 #define __wait_event_killable_timeout(wq_head, condition, timeout)              \
 764         ___wait_event(wq_head, ___wait_cond_timeout(condition),                 \
 765                       TASK_KILLABLE, 0, timeout,                                \
 766                       __ret = schedule_timeout(__ret))
 767
 768 /**
 769  * wait_event_killable_timeout - sleep until a condition gets true or a timeout elapses
 770  * @wq_head: the waitqueue to wait on
 771  * @condition: a C expression for the event to wait for
 772  * @timeout: timeout, in jiffies
 773  *
 774  * The process is put to sleep (TASK_KILLABLE) until the
 775  * @condition evaluates to true or a kill signal is received.
 776  * The @condition is checked each time the waitqueue @wq_head is woken up.
 777  *
 778  * wake_up() has to be called after changing any variable that could
 779  * change the result of the wait condition.
 780  *
 781  * Returns:
 782  * 0 if the @condition evaluated to %false after the @timeout elapsed,
 783  * 1 if the @condition evaluated to %true after the @timeout elapsed,
 784  * the remaining jiffies (at least 1) if the @condition evaluated
 785  * to %true before the @timeout elapsed, or -%ERESTARTSYS if it was
 786  * interrupted by a kill signal.
 787  *
 788  * Only kill signals interrupt this process.
 789  */
 790 #define wait_event_killable_timeout(wq_head, condition, timeout)                \
 791 ({                                                                              \
 792         long __ret = timeout;                                                   \
 793         might_sleep();                                                          \
 794         if (!___wait_cond_timeout(condition))                                   \
 795                 __ret = __wait_event_killable_timeout(wq_head,                  \
 796                                                 condition, timeout);            \
 797         __ret;                                                                  \
 798 })
 799
 800
 801 #define __wait_event_lock_irq(wq_head, condition, lock, cmd)                    \
 802         (void)___wait_event(wq_head, condition, TASK_UNINTERRUPTIBLE, 0, 0,     \
 803                             spin_unlock_irq(&lock);                             \
 804                             cmd;                                                \
 805                             schedule();                                         \
 806                             spin_lock_irq(&lock))
 807
 808 /**
 809  * wait_event_lock_irq_cmd - sleep until a condition gets true. The
 810  *                           condition is checked under the lock. This
 811  *                           is expected to be called with the lock
 812  *                           taken.
 813  * @wq_head: the waitqueue to wait on
 814  * @condition: a C expression for the event to wait for
 815  * @lock: a locked spinlock_t, which will be released before cmd
 816  *        and schedule() and reacquired afterwards.
 817  * @cmd: a command which is invoked outside the critical section before
 818  *       sleep
 819  *
 820  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 821  * @condition evaluates to true. The @condition is checked each time
 822  * the waitqueue @wq_head is woken up.
 823  *
 824  * wake_up() has to be called after changing any variable that could
 825  * change the result of the wait condition.
 826  *
 827  * This is supposed to be called while holding the lock. The lock is
 828  * dropped before invoking the cmd and going to sleep and is reacquired
 829  * afterwards.
 830  */
 831 #define wait_event_lock_irq_cmd(wq_head, condition, lock, cmd)                  \
 832 do {                                                                            \
 833         if (condition)                                                          \
 834                 break;                                                          \
 835         __wait_event_lock_irq(wq_head, condition, lock, cmd);                   \
 836 } while (0)
 837
 838 /**
 839  * wait_event_lock_irq - sleep until a condition gets true. The
 840  *                       condition is checked under the lock. This
 841  *                       is expected to be called with the lock
 842  *                       taken.
 843  * @wq_head: the waitqueue to wait on
 844  * @condition: a C expression for the event to wait for
 845  * @lock: a locked spinlock_t, which will be released before schedule()
 846  *        and reacquired afterwards.
 847  *
 848  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 849  * @condition evaluates to true. The @condition is checked each time
 850  * the waitqueue @wq_head is woken up.
 851  *
 852  * wake_up() has to be called after changing any variable that could
 853  * change the result of the wait condition.
 854  *
 855  * This is supposed to be called while holding the lock. The lock is
 856  * dropped before going to sleep and is reacquired afterwards.
 857  */
 858 #define wait_event_lock_irq(wq_head, condition, lock)                           \
 859 do {                                                                            \
 860         if (condition)                                                          \
 861                 break;                                                          \
 862         __wait_event_lock_irq(wq_head, condition, lock, );                      \
 863 } while (0)
 864
 865
 866 #define __wait_event_interruptible_lock_irq(wq_head, condition, lock, cmd)      \
 867         ___wait_event(wq_head, condition, TASK_INTERRUPTIBLE, 0, 0,             \
 868                       spin_unlock_irq(&lock);                                   \
 869                       cmd;                                                      \
 870                       schedule();                                               \
 871                       spin_lock_irq(&lock))
 872
 873 /**
 874  * wait_event_interruptible_lock_irq_cmd - sleep until a condition gets true.
 875  *              The condition is checked under the lock. This is expected to
 876  *              be called with the lock taken.
 877  * @wq_head: the waitqueue to wait on
 878  * @condition: a C expression for the event to wait for
 879  * @lock: a locked spinlock_t, which will be released before cmd and
 880  *        schedule() and reacquired afterwards.
 881  * @cmd: a command which is invoked outside the critical section before
 882  *       sleep
 883  *
 884  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 885  * @condition evaluates to true or a signal is received. The @condition is
 886  * checked each time the waitqueue @wq_head is woken up.
 887  *
 888  * wake_up() has to be called after changing any variable that could
 889  * change the result of the wait condition.
 890  *
 891  * This is supposed to be called while holding the lock. The lock is
 892  * dropped before invoking the cmd and going to sleep and is reacquired
 893  * afterwards.
 894  *
 895  * The macro will return -ERESTARTSYS if it was interrupted by a signal
 896  * and 0 if @condition evaluated to true.
 897  */
 898 #define wait_event_interruptible_lock_irq_cmd(wq_head, condition, lock, cmd)    \
 899 ({                                                                              \
 900         int __ret = 0;                                                          \
 901         if (!(condition))                                                       \
 902                 __ret = __wait_event_interruptible_lock_irq(wq_head,            \
 903                                                 condition, lock, cmd);          \
 904         __ret;                                                                  \
 905 })
 906
 907 /**
 908  * wait_event_interruptible_lock_irq - sleep until a condition gets true.
 909  *              The condition is checked under the lock. This is expected
 910  *              to be called with the lock taken.
 911  * @wq_head: the waitqueue to wait on
 912  * @condition: a C expression for the event to wait for
 913  * @lock: a locked spinlock_t, which will be released before schedule()
 914  *        and reacquired afterwards.
 915  *
 916  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 917  * @condition evaluates to true or signal is received. The @condition is
 918  * checked each time the waitqueue @wq_head is woken up.
 919  *
 920  * wake_up() has to be called after changing any variable that could
 921  * change the result of the wait condition.
 922  *
 923  * This is supposed to be called while holding the lock. The lock is
 924  * dropped before going to sleep and is reacquired afterwards.
 925  *
 926  * The macro will return -ERESTARTSYS if it was interrupted by a signal
 927  * and 0 if @condition evaluated to true.
 928  */
 929 #define wait_event_interruptible_lock_irq(wq_head, condition, lock)             \
 930 ({                                                                              \
 931         int __ret = 0;                                                          \
 932         if (!(condition))                                                       \
 933                 __ret = __wait_event_interruptible_lock_irq(wq_head,            \
 934                                                 condition, lock,);              \
 935         __ret;                                                                  \
 936 })
 937
 938 #define __wait_event_interruptible_lock_irq_timeout(wq_head, condition,         \
 939                                                     lock, timeout)              \
 940         ___wait_event(wq_head, ___wait_cond_timeout(condition),                 \
 941                       TASK_INTERRUPTIBLE, 0, timeout,                           \
 942                       spin_unlock_irq(&lock);                                   \
 943                       __ret = schedule_timeout(__ret);                          \
 944                       spin_lock_irq(&lock));
 945
 946 /**
 947  * wait_event_interruptible_lock_irq_timeout - sleep until a condition gets
 948  *              true or a timeout elapses. The condition is checked under
 949  *              the lock. This is expected to be called with the lock taken.
 950  * @wq_head: the waitqueue to wait on
 951  * @condition: a C expression for the event to wait for
 952  * @lock: a locked spinlock_t, which will be released before schedule()
 953  *        and reacquired afterwards.
 954  * @timeout: timeout, in jiffies
 955  *
 956  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 957  * @condition evaluates to true or signal is received. The @condition is
 958  * checked each time the waitqueue @wq_head is woken up.
 959  *
 960  * wake_up() has to be called after changing any variable that could
 961  * change the result of the wait condition.
 962  *
 963  * This is supposed to be called while holding the lock. The lock is
 964  * dropped before going to sleep and is reacquired afterwards.
 965  *
 966  * The function returns 0 if the @timeout elapsed, -ERESTARTSYS if it
 967  * was interrupted by a signal, and the remaining jiffies otherwise
 968  * if the condition evaluated to true before the timeout elapsed.
 969  */
 970 #define wait_event_interruptible_lock_irq_timeout(wq_head, condition, lock,     \
 971                                                   timeout)                      \
 972 ({                                                                              \
 973         long __ret = timeout;                                                   \
 974         if (!___wait_cond_timeout(condition))                                   \
 975                 __ret = __wait_event_interruptible_lock_irq_timeout(            \
 976                                         wq_head, condition, lock, timeout);     \
 977         __ret;                                                                  \
 978 })
 979
 980 /*
 981  * Waitqueues which are removed from the waitqueue_head at wakeup time
 982  */
 983 void prepare_to_wait(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry, int state);
 984 void prepare_to_wait_exclusive(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry, int state);
 985 long prepare_to_wait_event(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry, int state);
 986 void finish_wait(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry);
 987 long wait_woken(struct wait_queue_entry *wq_entry, unsigned mode, long timeout);
 988 int woken_wake_function(struct wait_queue_entry *wq_entry, unsigned mode, int sync, void *key);
 989 int autoremove_wake_function(struct wait_queue_entry *wq_entry, unsigned mode, int sync, void *key);
 990
 991 #define DEFINE_WAIT_FUNC(name, function)                                        \
 992         struct wait_queue_entry name = {                                        \
 993                 .private        = current,                                      \
 994                 .func           = function,                                     \
 995                 .entry          = LIST_HEAD_INIT((name).entry),                 \
 996         }
 997
 998 #define DEFINE_WAIT(name) DEFINE_WAIT_FUNC(name, autoremove_wake_function)
 999
1000 #define init_wait(wait)                                                         \
1001         do {                                                                    \
1002                 (wait)->private = current;                                      \
1003                 (wait)->func = autoremove_wake_function;                        \
1004                 INIT_LIST_HEAD(&(wait)->entry);                                 \
1005                 (wait)->flags = 0;                                              \
1006         } while (0)
1007
1008 #endif /* _LINUX_WAIT_H */