include/linux/wait.h

   1 #ifndef _LINUX_WAIT_H
   2 #define _LINUX_WAIT_H
   3 /*
   4  * Linux wait queue related types and methods
   5  */
   6 #include <linux/list.h>
   7 #include <linux/stddef.h>
   8 #include <linux/spinlock.h>
   9 #include <asm/current.h>
  10 #include <uapi/linux/wait.h>
  11
  12 typedef struct __wait_queue wait_queue_t;
  13 typedef int (*wait_queue_func_t)(wait_queue_t *wait, unsigned mode, int flags, void *key);
  14 int default_wake_function(wait_queue_t *wait, unsigned mode, int flags, void *key);
  15
  16 /* __wait_queue::flags */
  17 #define WQ_FLAG_EXCLUSIVE       0x01
  18 #define WQ_FLAG_WOKEN           0x02
  19
  20 struct __wait_queue {
  21         unsigned int            flags;
  22         void                    *private;
  23         wait_queue_func_t       func;
  24         struct list_head        task_list;
  25 };
  26
  27 struct wait_bit_key {
  28         void                    *flags;
  29         int                     bit_nr;
  30 #define WAIT_ATOMIC_T_BIT_NR    -1
  31         unsigned long           timeout;
  32 };
  33
  34 struct wait_bit_queue {
  35         struct wait_bit_key     key;
  36         wait_queue_t            wait;
  37 };
  38
  39 struct __wait_queue_head {
  40         spinlock_t              lock;
  41         struct list_head        task_list;
  42 };
  43 typedef struct __wait_queue_head wait_queue_head_t;
  44
  45 struct task_struct;
  46
  47 /*
  48  * Macros for declaration and initialisaton of the datatypes
  49  */
  50
  51 #define __WAITQUEUE_INITIALIZER(name, tsk) {                            \
  52         .private        = tsk,                                          \
  53         .func           = default_wake_function,                        \
  54         .task_list      = { NULL, NULL } }
  55
  56 #define DECLARE_WAITQUEUE(name, tsk)                                    \
  57         wait_queue_t name = __WAITQUEUE_INITIALIZER(name, tsk)
  58
  59 #define __WAIT_QUEUE_HEAD_INITIALIZER(name) {                           \
  60         .lock           = __SPIN_LOCK_UNLOCKED(name.lock),              \
  61         .task_list      = { &(name).task_list, &(name).task_list } }
  62
  63 #define DECLARE_WAIT_QUEUE_HEAD(name) \
  64         wait_queue_head_t name = __WAIT_QUEUE_HEAD_INITIALIZER(name)
  65
  66 #define __WAIT_BIT_KEY_INITIALIZER(word, bit)                           \
  67         { .flags = word, .bit_nr = bit, }
  68
  69 #define __WAIT_ATOMIC_T_KEY_INITIALIZER(p)                              \
  70         { .flags = p, .bit_nr = WAIT_ATOMIC_T_BIT_NR, }
  71
  72 extern void __init_waitqueue_head(wait_queue_head_t *q, const char *name, struct lock_class_key *);
  73
  74 #define init_waitqueue_head(q)                          \
  75         do {                                            \
  76                 static struct lock_class_key __key;     \
  77                                                         \
  78                 __init_waitqueue_head((q), #q, &__key); \
  79         } while (0)
  80
  81 #ifdef CONFIG_LOCKDEP
  82 # define __WAIT_QUEUE_HEAD_INIT_ONSTACK(name) \
  83         ({ init_waitqueue_head(&name); name; })
  84 # define DECLARE_WAIT_QUEUE_HEAD_ONSTACK(name) \
  85         wait_queue_head_t name = __WAIT_QUEUE_HEAD_INIT_ONSTACK(name)
  86 #else
  87 # define DECLARE_WAIT_QUEUE_HEAD_ONSTACK(name) DECLARE_WAIT_QUEUE_HEAD(name)
  88 #endif
  89
  90 static inline void init_waitqueue_entry(wait_queue_t *q, struct task_struct *p)
  91 {
  92         q->flags        = 0;
  93         q->private      = p;
  94         q->func         = default_wake_function;
  95 }
  96
  97 static inline void
  98 init_waitqueue_func_entry(wait_queue_t *q, wait_queue_func_t func)
  99 {
 100         q->flags        = 0;
 101         q->private      = NULL;
 102         q->func         = func;
 103 }
 104
 105 static inline int waitqueue_active(wait_queue_head_t *q)
 106 {
 107         return !list_empty(&q->task_list);
 108 }
 109
 110 extern void add_wait_queue(wait_queue_head_t *q, wait_queue_t *wait);
 111 extern void add_wait_queue_exclusive(wait_queue_head_t *q, wait_queue_t *wait);
 112 extern void remove_wait_queue(wait_queue_head_t *q, wait_queue_t *wait);
 113
 114 static inline void __add_wait_queue(wait_queue_head_t *head, wait_queue_t *new)
 115 {
 116         list_add(&new->task_list, &head->task_list);
 117 }
 118
 119 /*
 120  * Used for wake-one threads:
 121  */
 122 static inline void
 123 __add_wait_queue_exclusive(wait_queue_head_t *q, wait_queue_t *wait)
 124 {
 125         wait->flags |= WQ_FLAG_EXCLUSIVE;
 126         __add_wait_queue(q, wait);
 127 }
 128
 129 static inline void __add_wait_queue_tail(wait_queue_head_t *head,
 130                                          wait_queue_t *new)
 131 {
 132         list_add_tail(&new->task_list, &head->task_list);
 133 }
 134
 135 static inline void
 136 __add_wait_queue_tail_exclusive(wait_queue_head_t *q, wait_queue_t *wait)
 137 {
 138         wait->flags |= WQ_FLAG_EXCLUSIVE;
 139         __add_wait_queue_tail(q, wait);
 140 }
 141
 142 static inline void
 143 __remove_wait_queue(wait_queue_head_t *head, wait_queue_t *old)
 144 {
 145         list_del(&old->task_list);
 146 }
 147
 148 typedef int wait_bit_action_f(struct wait_bit_key *);
 149 void __wake_up(wait_queue_head_t *q, unsigned int mode, int nr, void *key);
 150 void __wake_up_locked_key(wait_queue_head_t *q, unsigned int mode, void *key);
 151 void __wake_up_sync_key(wait_queue_head_t *q, unsigned int mode, int nr, void *key);
 152 void __wake_up_locked(wait_queue_head_t *q, unsigned int mode, int nr);
 153 void __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr);
 154 void __wake_up_bit(wait_queue_head_t *, void *, int);
 155 int __wait_on_bit(wait_queue_head_t *, struct wait_bit_queue *, wait_bit_action_f *, unsigned);
 156 int __wait_on_bit_lock(wait_queue_head_t *, struct wait_bit_queue *, wait_bit_action_f *, unsigned);
 157 void wake_up_bit(void *, int);
 158 void wake_up_atomic_t(atomic_t *);
 159 int out_of_line_wait_on_bit(void *, int, wait_bit_action_f *, unsigned);
 160 int out_of_line_wait_on_bit_timeout(void *, int, wait_bit_action_f *, unsigned, unsigned long);
 161 int out_of_line_wait_on_bit_lock(void *, int, wait_bit_action_f *, unsigned);
 162 int out_of_line_wait_on_atomic_t(atomic_t *, int (*)(atomic_t *), unsigned);
 163 wait_queue_head_t *bit_waitqueue(void *, int);
 164
 165 #define wake_up(x)                      __wake_up(x, TASK_NORMAL, 1, NULL)
 166 #define wake_up_nr(x, nr)               __wake_up(x, TASK_NORMAL, nr, NULL)
 167 #define wake_up_all(x)                  __wake_up(x, TASK_NORMAL, 0, NULL)
 168 #define wake_up_locked(x)               __wake_up_locked((x), TASK_NORMAL, 1)
 169 #define wake_up_all_locked(x)           __wake_up_locked((x), TASK_NORMAL, 0)
 170
 171 #define wake_up_interruptible(x)        __wake_up(x, TASK_INTERRUPTIBLE, 1, NULL)
 172 #define wake_up_interruptible_nr(x, nr) __wake_up(x, TASK_INTERRUPTIBLE, nr, NULL)
 173 #define wake_up_interruptible_all(x)    __wake_up(x, TASK_INTERRUPTIBLE, 0, NULL)
 174 #define wake_up_interruptible_sync(x)   __wake_up_sync((x), TASK_INTERRUPTIBLE, 1)
 175
 176 /*
 177  * Wakeup macros to be used to report events to the targets.
 178  */
 179 #define wake_up_poll(x, m)                                              \
 180         __wake_up(x, TASK_NORMAL, 1, (void *) (m))
 181 #define wake_up_locked_poll(x, m)                                       \
 182         __wake_up_locked_key((x), TASK_NORMAL, (void *) (m))
 183 #define wake_up_interruptible_poll(x, m)                                \
 184         __wake_up(x, TASK_INTERRUPTIBLE, 1, (void *) (m))
 185 #define wake_up_interruptible_sync_poll(x, m)                           \
 186         __wake_up_sync_key((x), TASK_INTERRUPTIBLE, 1, (void *) (m))
 187
 188 #define ___wait_cond_timeout(condition)                                 \
 189 ({                                                                      \
 190         bool __cond = (condition);                                      \
 191         if (__cond && !__ret)                                           \
 192                 __ret = 1;                                              \
 193         __cond || !__ret;                                               \
 194 })
 195
 196 #define ___wait_is_interruptible(state)                                 \
 197         (!__builtin_constant_p(state) ||                                \
 198                 state == TASK_INTERRUPTIBLE || state == TASK_KILLABLE)  \
 199
 200 /*
 201  * The below macro ___wait_event() has an explicit shadow of the __ret
 202  * variable when used from the wait_event_*() macros.
 203  *
 204  * This is so that both can use the ___wait_cond_timeout() construct
 205  * to wrap the condition.
 206  *
 207  * The type inconsistency of the wait_event_*() __ret variable is also
 208  * on purpose; we use long where we can return timeout values and int
 209  * otherwise.
 210  */
 211
 212 #define ___wait_event(wq, condition, state, exclusive, ret, cmd)        \
 213 ({                                                                      \
 214         __label__ __out;                                                \
 215         wait_queue_t __wait;                                            \
 216         long __ret = ret;       /* explicit shadow */                   \
 217                                                                         \
 218         INIT_LIST_HEAD(&__wait.task_list);                              \
 219         if (exclusive)                                                  \
 220                 __wait.flags = WQ_FLAG_EXCLUSIVE;                       \
 221         else                                                            \
 222                 __wait.flags = 0;                                       \
 223                                                                         \
 224         for (;;) {                                                      \
 225                 long __int = prepare_to_wait_event(&wq, &__wait, state);\
 226                                                                         \
 227                 if (condition)                                          \
 228                         break;                                          \
 229                                                                         \
 230                 if (___wait_is_interruptible(state) && __int) {         \
 231                         __ret = __int;                                  \
 232                         if (exclusive) {                                \
 233                                 abort_exclusive_wait(&wq, &__wait,      \
 234                                                      state, NULL);      \
 235                                 goto __out;                             \
 236                         }                                               \
 237                         break;                                          \
 238                 }                                                       \
 239                                                                         \
 240                 cmd;                                                    \
 241         }                                                               \
 242         finish_wait(&wq, &__wait);                                      \
 243 __out:  __ret;                                                          \
 244 })
 245
 246 #define __wait_event(wq, condition)                                     \
 247         (void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0, 0,  \
 248                             schedule())
 249
 250 /**
 251  * wait_event - sleep until a condition gets true
 252  * @wq: the waitqueue to wait on
 253  * @condition: a C expression for the event to wait for
 254  *
 255  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 256  * @condition evaluates to true. The @condition is checked each time
 257  * the waitqueue @wq is woken up.
 258  *
 259  * wake_up() has to be called after changing any variable that could
 260  * change the result of the wait condition.
 261  */
 262 #define wait_event(wq, condition)                                       \
 263 do {                                                                    \
 264         might_sleep();                                                  \
 265         if (condition)                                                  \
 266                 break;                                                  \
 267         __wait_event(wq, condition);                                    \
 268 } while (0)
 269
 270 #define __io_wait_event(wq, condition)                                  \
 271         (void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0, 0,  \
 272                             io_schedule())
 273
 274 /*
 275  * io_wait_event() -- like wait_event() but with io_schedule()
 276  */
 277 #define io_wait_event(wq, condition)                                    \
 278 do {                                                                    \
 279         might_sleep();                                                  \
 280         if (condition)                                                  \
 281                 break;                                                  \
 282         __io_wait_event(wq, condition);                                 \
 283 } while (0)
 284
 285 #define __wait_event_freezable(wq, condition)                           \
 286         ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 0, 0,          \
 287                             schedule(); try_to_freeze())
 288
 289 /**
 290  * wait_event - sleep (or freeze) until a condition gets true
 291  * @wq: the waitqueue to wait on
 292  * @condition: a C expression for the event to wait for
 293  *
 294  * The process is put to sleep (TASK_INTERRUPTIBLE -- so as not to contribute
 295  * to system load) until the @condition evaluates to true. The
 296  * @condition is checked each time the waitqueue @wq is woken up.
 297  *
 298  * wake_up() has to be called after changing any variable that could
 299  * change the result of the wait condition.
 300  */
 301 #define wait_event_freezable(wq, condition)                             \
 302 ({                                                                      \
 303         int __ret = 0;                                                  \
 304         might_sleep();                                                  \
 305         if (!(condition))                                               \
 306                 __ret = __wait_event_freezable(wq, condition);          \
 307         __ret;                                                          \
 308 })
 309
 310 #define __wait_event_timeout(wq, condition, timeout)                    \
 311         ___wait_event(wq, ___wait_cond_timeout(condition),              \
 312                       TASK_UNINTERRUPTIBLE, 0, timeout,                 \
 313                       __ret = schedule_timeout(__ret))
 314
 315 /**
 316  * wait_event_timeout - sleep until a condition gets true or a timeout elapses
 317  * @wq: the waitqueue to wait on
 318  * @condition: a C expression for the event to wait for
 319  * @timeout: timeout, in jiffies
 320  *
 321  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 322  * @condition evaluates to true. The @condition is checked each time
 323  * the waitqueue @wq is woken up.
 324  *
 325  * wake_up() has to be called after changing any variable that could
 326  * change the result of the wait condition.
 327  *
 328  * Returns:
 329  * 0 if the @condition evaluated to %false after the @timeout elapsed,
 330  * 1 if the @condition evaluated to %true after the @timeout elapsed,
 331  * or the remaining jiffies (at least 1) if the @condition evaluated
 332  * to %true before the @timeout elapsed.
 333  */
 334 #define wait_event_timeout(wq, condition, timeout)                      \
 335 ({                                                                      \
 336         long __ret = timeout;                                           \
 337         might_sleep();                                                  \
 338         if (!___wait_cond_timeout(condition))                           \
 339                 __ret = __wait_event_timeout(wq, condition, timeout);   \
 340         __ret;                                                          \
 341 })
 342
 343 #define __wait_event_freezable_timeout(wq, condition, timeout)          \
 344         ___wait_event(wq, ___wait_cond_timeout(condition),              \
 345                       TASK_INTERRUPTIBLE, 0, timeout,                   \
 346                       __ret = schedule_timeout(__ret); try_to_freeze())
 347
 348 /*
 349  * like wait_event_timeout() -- except it uses TASK_INTERRUPTIBLE to avoid
 350  * increasing load and is freezable.
 351  */
 352 #define wait_event_freezable_timeout(wq, condition, timeout)            \
 353 ({                                                                      \
 354         long __ret = timeout;                                           \
 355         might_sleep();                                                  \
 356         if (!___wait_cond_timeout(condition))                           \
 357                 __ret = __wait_event_freezable_timeout(wq, condition, timeout); \
 358         __ret;                                                          \
 359 })
 360
 361 #define __wait_event_exclusive_cmd(wq, condition, cmd1, cmd2)           \
 362         (void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 1, 0,  \
 363                             cmd1; schedule(); cmd2)
 364 /*
 365  * Just like wait_event_cmd(), except it sets exclusive flag
 366  */
 367 #define wait_event_exclusive_cmd(wq, condition, cmd1, cmd2)             \
 368 do {                                                                    \
 369         if (condition)                                                  \
 370                 break;                                                  \
 371         __wait_event_exclusive_cmd(wq, condition, cmd1, cmd2);          \
 372 } while (0)
 373
 374 #define __wait_event_cmd(wq, condition, cmd1, cmd2)                     \
 375         (void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0, 0,  \
 376                             cmd1; schedule(); cmd2)
 377
 378 /**
 379  * wait_event_cmd - sleep until a condition gets true
 380  * @wq: the waitqueue to wait on
 381  * @condition: a C expression for the event to wait for
 382  * @cmd1: the command will be executed before sleep
 383  * @cmd2: the command will be executed after sleep
 384  *
 385  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 386  * @condition evaluates to true. The @condition is checked each time
 387  * the waitqueue @wq is woken up.
 388  *
 389  * wake_up() has to be called after changing any variable that could
 390  * change the result of the wait condition.
 391  */
 392 #define wait_event_cmd(wq, condition, cmd1, cmd2)                       \
 393 do {                                                                    \
 394         if (condition)                                                  \
 395                 break;                                                  \
 396         __wait_event_cmd(wq, condition, cmd1, cmd2);                    \
 397 } while (0)
 398
 399 #define __wait_event_interruptible(wq, condition)                       \
 400         ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 0, 0,          \
 401                       schedule())
 402
 403 /**
 404  * wait_event_interruptible - sleep until a condition gets true
 405  * @wq: the waitqueue to wait on
 406  * @condition: a C expression for the event to wait for
 407  *
 408  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 409  * @condition evaluates to true or a signal is received.
 410  * The @condition is checked each time the waitqueue @wq is woken up.
 411  *
 412  * wake_up() has to be called after changing any variable that could
 413  * change the result of the wait condition.
 414  *
 415  * The function will return -ERESTARTSYS if it was interrupted by a
 416  * signal and 0 if @condition evaluated to true.
 417  */
 418 #define wait_event_interruptible(wq, condition)                         \
 419 ({                                                                      \
 420         int __ret = 0;                                                  \
 421         might_sleep();                                                  \
 422         if (!(condition))                                               \
 423                 __ret = __wait_event_interruptible(wq, condition);      \
 424         __ret;                                                          \
 425 })
 426
 427 #define __wait_event_interruptible_timeout(wq, condition, timeout)      \
 428         ___wait_event(wq, ___wait_cond_timeout(condition),              \
 429                       TASK_INTERRUPTIBLE, 0, timeout,                   \
 430                       __ret = schedule_timeout(__ret))
 431
 432 /**
 433  * wait_event_interruptible_timeout - sleep until a condition gets true or a timeout elapses
 434  * @wq: the waitqueue to wait on
 435  * @condition: a C expression for the event to wait for
 436  * @timeout: timeout, in jiffies
 437  *
 438  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 439  * @condition evaluates to true or a signal is received.
 440  * The @condition is checked each time the waitqueue @wq is woken up.
 441  *
 442  * wake_up() has to be called after changing any variable that could
 443  * change the result of the wait condition.
 444  *
 445  * Returns:
 446  * 0 if the @condition evaluated to %false after the @timeout elapsed,
 447  * 1 if the @condition evaluated to %true after the @timeout elapsed,
 448  * the remaining jiffies (at least 1) if the @condition evaluated
 449  * to %true before the @timeout elapsed, or -%ERESTARTSYS if it was
 450  * interrupted by a signal.
 451  */
 452 #define wait_event_interruptible_timeout(wq, condition, timeout)        \
 453 ({                                                                      \
 454         long __ret = timeout;                                           \
 455         might_sleep();                                                  \
 456         if (!___wait_cond_timeout(condition))                           \
 457                 __ret = __wait_event_interruptible_timeout(wq,          \
 458                                                 condition, timeout);    \
 459         __ret;                                                          \
 460 })
 461
 462 #define __wait_event_hrtimeout(wq, condition, timeout, state)           \
 463 ({                                                                      \
 464         int __ret = 0;                                                  \
 465         struct hrtimer_sleeper __t;                                     \
 466                                                                         \
 467         hrtimer_init_on_stack(&__t.timer, CLOCK_MONOTONIC,              \
 468                               HRTIMER_MODE_REL);                        \
 469         hrtimer_init_sleeper(&__t, current);                            \
 470         if ((timeout).tv64 != KTIME_MAX)                                \
 471                 hrtimer_start_range_ns(&__t.timer, timeout,             \
 472                                        current->timer_slack_ns,         \
 473                                        HRTIMER_MODE_REL);               \
 474                                                                         \
 475         __ret = ___wait_event(wq, condition, state, 0, 0,               \
 476                 if (!__t.task) {                                        \
 477                         __ret = -ETIME;                                 \
 478                         break;                                          \
 479                 }                                                       \
 480                 schedule());                                            \
 481                                                                         \
 482         hrtimer_cancel(&__t.timer);                                     \
 483         destroy_hrtimer_on_stack(&__t.timer);                           \
 484         __ret;                                                          \
 485 })
 486
 487 /**
 488  * wait_event_hrtimeout - sleep until a condition gets true or a timeout elapses
 489  * @wq: the waitqueue to wait on
 490  * @condition: a C expression for the event to wait for
 491  * @timeout: timeout, as a ktime_t
 492  *
 493  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 494  * @condition evaluates to true or a signal is received.
 495  * The @condition is checked each time the waitqueue @wq is woken up.
 496  *
 497  * wake_up() has to be called after changing any variable that could
 498  * change the result of the wait condition.
 499  *
 500  * The function returns 0 if @condition became true, or -ETIME if the timeout
 501  * elapsed.
 502  */
 503 #define wait_event_hrtimeout(wq, condition, timeout)                    \
 504 ({                                                                      \
 505         int __ret = 0;                                                  \
 506         might_sleep();                                                  \
 507         if (!(condition))                                               \
 508                 __ret = __wait_event_hrtimeout(wq, condition, timeout,  \
 509                                                TASK_UNINTERRUPTIBLE);   \
 510         __ret;                                                          \
 511 })
 512
 513 /**
 514  * wait_event_interruptible_hrtimeout - sleep until a condition gets true or a timeout elapses
 515  * @wq: the waitqueue to wait on
 516  * @condition: a C expression for the event to wait for
 517  * @timeout: timeout, as a ktime_t
 518  *
 519  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 520  * @condition evaluates to true or a signal is received.
 521  * The @condition is checked each time the waitqueue @wq is woken up.
 522  *
 523  * wake_up() has to be called after changing any variable that could
 524  * change the result of the wait condition.
 525  *
 526  * The function returns 0 if @condition became true, -ERESTARTSYS if it was
 527  * interrupted by a signal, or -ETIME if the timeout elapsed.
 528  */
 529 #define wait_event_interruptible_hrtimeout(wq, condition, timeout)      \
 530 ({                                                                      \
 531         long __ret = 0;                                                 \
 532         might_sleep();                                                  \
 533         if (!(condition))                                               \
 534                 __ret = __wait_event_hrtimeout(wq, condition, timeout,  \
 535                                                TASK_INTERRUPTIBLE);     \
 536         __ret;                                                          \
 537 })
 538
 539 #define __wait_event_interruptible_exclusive(wq, condition)             \
 540         ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 1, 0,          \
 541                       schedule())
 542
 543 #define wait_event_interruptible_exclusive(wq, condition)               \
 544 ({                                                                      \
 545         int __ret = 0;                                                  \
 546         might_sleep();                                                  \
 547         if (!(condition))                                               \
 548                 __ret = __wait_event_interruptible_exclusive(wq, condition);\
 549         __ret;                                                          \
 550 })
 551
 552
 553 #define __wait_event_freezable_exclusive(wq, condition)                 \
 554         ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 1, 0,          \
 555                         schedule(); try_to_freeze())
 556
 557 #define wait_event_freezable_exclusive(wq, condition)                   \
 558 ({                                                                      \
 559         int __ret = 0;                                                  \
 560         might_sleep();                                                  \
 561         if (!(condition))                                               \
 562                 __ret = __wait_event_freezable_exclusive(wq, condition);\
 563         __ret;                                                          \
 564 })
 565
 566
 567 #define __wait_event_interruptible_locked(wq, condition, exclusive, irq) \
 568 ({                                                                      \
 569         int __ret = 0;                                                  \
 570         DEFINE_WAIT(__wait);                                            \
 571         if (exclusive)                                                  \
 572                 __wait.flags |= WQ_FLAG_EXCLUSIVE;                      \
 573         do {                                                            \
 574                 if (likely(list_empty(&__wait.task_list)))              \
 575                         __add_wait_queue_tail(&(wq), &__wait);          \
 576                 set_current_state(TASK_INTERRUPTIBLE);                  \
 577                 if (signal_pending(current)) {                          \
 578                         __ret = -ERESTARTSYS;                           \
 579                         break;                                          \
 580                 }                                                       \
 581                 if (irq)                                                \
 582                         spin_unlock_irq(&(wq).lock);                    \
 583                 else                                                    \
 584                         spin_unlock(&(wq).lock);                        \
 585                 schedule();                                             \
 586                 if (irq)                                                \
 587                         spin_lock_irq(&(wq).lock);                      \
 588                 else                                                    \
 589                         spin_lock(&(wq).lock);                          \
 590         } while (!(condition));                                         \
 591         __remove_wait_queue(&(wq), &__wait);                            \
 592         __set_current_state(TASK_RUNNING);                              \
 593         __ret;                                                          \
 594 })
 595
 596
 597 /**
 598  * wait_event_interruptible_locked - sleep until a condition gets true
 599  * @wq: the waitqueue to wait on
 600  * @condition: a C expression for the event to wait for
 601  *
 602  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 603  * @condition evaluates to true or a signal is received.
 604  * The @condition is checked each time the waitqueue @wq is woken up.
 605  *
 606  * It must be called with wq.lock being held.  This spinlock is
 607  * unlocked while sleeping but @condition testing is done while lock
 608  * is held and when this macro exits the lock is held.
 609  *
 610  * The lock is locked/unlocked using spin_lock()/spin_unlock()
 611  * functions which must match the way they are locked/unlocked outside
 612  * of this macro.
 613  *
 614  * wake_up_locked() has to be called after changing any variable that could
 615  * change the result of the wait condition.
 616  *
 617  * The function will return -ERESTARTSYS if it was interrupted by a
 618  * signal and 0 if @condition evaluated to true.
 619  */
 620 #define wait_event_interruptible_locked(wq, condition)                  \
 621         ((condition)                                                    \
 622          ? 0 : __wait_event_interruptible_locked(wq, condition, 0, 0))
 623
 624 /**
 625  * wait_event_interruptible_locked_irq - sleep until a condition gets true
 626  * @wq: the waitqueue to wait on
 627  * @condition: a C expression for the event to wait for
 628  *
 629  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 630  * @condition evaluates to true or a signal is received.
 631  * The @condition is checked each time the waitqueue @wq is woken up.
 632  *
 633  * It must be called with wq.lock being held.  This spinlock is
 634  * unlocked while sleeping but @condition testing is done while lock
 635  * is held and when this macro exits the lock is held.
 636  *
 637  * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq()
 638  * functions which must match the way they are locked/unlocked outside
 639  * of this macro.
 640  *
 641  * wake_up_locked() has to be called after changing any variable that could
 642  * change the result of the wait condition.
 643  *
 644  * The function will return -ERESTARTSYS if it was interrupted by a
 645  * signal and 0 if @condition evaluated to true.
 646  */
 647 #define wait_event_interruptible_locked_irq(wq, condition)              \
 648         ((condition)                                                    \
 649          ? 0 : __wait_event_interruptible_locked(wq, condition, 0, 1))
 650
 651 /**
 652  * wait_event_interruptible_exclusive_locked - sleep exclusively until a condition gets true
 653  * @wq: the waitqueue to wait on
 654  * @condition: a C expression for the event to wait for
 655  *
 656  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 657  * @condition evaluates to true or a signal is received.
 658  * The @condition is checked each time the waitqueue @wq is woken up.
 659  *
 660  * It must be called with wq.lock being held.  This spinlock is
 661  * unlocked while sleeping but @condition testing is done while lock
 662  * is held and when this macro exits the lock is held.
 663  *
 664  * The lock is locked/unlocked using spin_lock()/spin_unlock()
 665  * functions which must match the way they are locked/unlocked outside
 666  * of this macro.
 667  *
 668  * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
 669  * set thus when other process waits process on the list if this
 670  * process is awaken further processes are not considered.
 671  *
 672  * wake_up_locked() has to be called after changing any variable that could
 673  * change the result of the wait condition.
 674  *
 675  * The function will return -ERESTARTSYS if it was interrupted by a
 676  * signal and 0 if @condition evaluated to true.
 677  */
 678 #define wait_event_interruptible_exclusive_locked(wq, condition)        \
 679         ((condition)                                                    \
 680          ? 0 : __wait_event_interruptible_locked(wq, condition, 1, 0))
 681
 682 /**
 683  * wait_event_interruptible_exclusive_locked_irq - sleep until a condition gets true
 684  * @wq: the waitqueue to wait on
 685  * @condition: a C expression for the event to wait for
 686  *
 687  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 688  * @condition evaluates to true or a signal is received.
 689  * The @condition is checked each time the waitqueue @wq is woken up.
 690  *
 691  * It must be called with wq.lock being held.  This spinlock is
 692  * unlocked while sleeping but @condition testing is done while lock
 693  * is held and when this macro exits the lock is held.
 694  *
 695  * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq()
 696  * functions which must match the way they are locked/unlocked outside
 697  * of this macro.
 698  *
 699  * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
 700  * set thus when other process waits process on the list if this
 701  * process is awaken further processes are not considered.
 702  *
 703  * wake_up_locked() has to be called after changing any variable that could
 704  * change the result of the wait condition.
 705  *
 706  * The function will return -ERESTARTSYS if it was interrupted by a
 707  * signal and 0 if @condition evaluated to true.
 708  */
 709 #define wait_event_interruptible_exclusive_locked_irq(wq, condition)    \
 710         ((condition)                                                    \
 711          ? 0 : __wait_event_interruptible_locked(wq, condition, 1, 1))
 712
 713
 714 #define __wait_event_killable(wq, condition)                            \
 715         ___wait_event(wq, condition, TASK_KILLABLE, 0, 0, schedule())
 716
 717 /**
 718  * wait_event_killable - sleep until a condition gets true
 719  * @wq: the waitqueue to wait on
 720  * @condition: a C expression for the event to wait for
 721  *
 722  * The process is put to sleep (TASK_KILLABLE) until the
 723  * @condition evaluates to true or a signal is received.
 724  * The @condition is checked each time the waitqueue @wq is woken up.
 725  *
 726  * wake_up() has to be called after changing any variable that could
 727  * change the result of the wait condition.
 728  *
 729  * The function will return -ERESTARTSYS if it was interrupted by a
 730  * signal and 0 if @condition evaluated to true.
 731  */
 732 #define wait_event_killable(wq, condition)                              \
 733 ({                                                                      \
 734         int __ret = 0;                                                  \
 735         might_sleep();                                                  \
 736         if (!(condition))                                               \
 737                 __ret = __wait_event_killable(wq, condition);           \
 738         __ret;                                                          \
 739 })
 740
 741
 742 #define __wait_event_lock_irq(wq, condition, lock, cmd)                 \
 743         (void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0, 0,  \
 744                             spin_unlock_irq(&lock);                     \
 745                             cmd;                                        \
 746                             schedule();                                 \
 747                             spin_lock_irq(&lock))
 748
 749 /**
 750  * wait_event_lock_irq_cmd - sleep until a condition gets true. The
 751  *                           condition is checked under the lock. This
 752  *                           is expected to be called with the lock
 753  *                           taken.
 754  * @wq: the waitqueue to wait on
 755  * @condition: a C expression for the event to wait for
 756  * @lock: a locked spinlock_t, which will be released before cmd
 757  *        and schedule() and reacquired afterwards.
 758  * @cmd: a command which is invoked outside the critical section before
 759  *       sleep
 760  *
 761  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 762  * @condition evaluates to true. The @condition is checked each time
 763  * the waitqueue @wq is woken up.
 764  *
 765  * wake_up() has to be called after changing any variable that could
 766  * change the result of the wait condition.
 767  *
 768  * This is supposed to be called while holding the lock. The lock is
 769  * dropped before invoking the cmd and going to sleep and is reacquired
 770  * afterwards.
 771  */
 772 #define wait_event_lock_irq_cmd(wq, condition, lock, cmd)               \
 773 do {                                                                    \
 774         if (condition)                                                  \
 775                 break;                                                  \
 776         __wait_event_lock_irq(wq, condition, lock, cmd);                \
 777 } while (0)
 778
 779 /**
 780  * wait_event_lock_irq - sleep until a condition gets true. The
 781  *                       condition is checked under the lock. This
 782  *                       is expected to be called with the lock
 783  *                       taken.
 784  * @wq: the waitqueue to wait on
 785  * @condition: a C expression for the event to wait for
 786  * @lock: a locked spinlock_t, which will be released before schedule()
 787  *        and reacquired afterwards.
 788  *
 789  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 790  * @condition evaluates to true. The @condition is checked each time
 791  * the waitqueue @wq is woken up.
 792  *
 793  * wake_up() has to be called after changing any variable that could
 794  * change the result of the wait condition.
 795  *
 796  * This is supposed to be called while holding the lock. The lock is
 797  * dropped before going to sleep and is reacquired afterwards.
 798  */
 799 #define wait_event_lock_irq(wq, condition, lock)                        \
 800 do {                                                                    \
 801         if (condition)                                                  \
 802                 break;                                                  \
 803         __wait_event_lock_irq(wq, condition, lock, );                   \
 804 } while (0)
 805
 806
 807 #define __wait_event_interruptible_lock_irq(wq, condition, lock, cmd)   \
 808         ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 0, 0,          \
 809                       spin_unlock_irq(&lock);                           \
 810                       cmd;                                              \
 811                       schedule();                                       \
 812                       spin_lock_irq(&lock))
 813
 814 /**
 815  * wait_event_interruptible_lock_irq_cmd - sleep until a condition gets true.
 816  *              The condition is checked under the lock. This is expected to
 817  *              be called with the lock taken.
 818  * @wq: the waitqueue to wait on
 819  * @condition: a C expression for the event to wait for
 820  * @lock: a locked spinlock_t, which will be released before cmd and
 821  *        schedule() and reacquired afterwards.
 822  * @cmd: a command which is invoked outside the critical section before
 823  *       sleep
 824  *
 825  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 826  * @condition evaluates to true or a signal is received. The @condition is
 827  * checked each time the waitqueue @wq is woken up.
 828  *
 829  * wake_up() has to be called after changing any variable that could
 830  * change the result of the wait condition.
 831  *
 832  * This is supposed to be called while holding the lock. The lock is
 833  * dropped before invoking the cmd and going to sleep and is reacquired
 834  * afterwards.
 835  *
 836  * The macro will return -ERESTARTSYS if it was interrupted by a signal
 837  * and 0 if @condition evaluated to true.
 838  */
 839 #define wait_event_interruptible_lock_irq_cmd(wq, condition, lock, cmd) \
 840 ({                                                                      \
 841         int __ret = 0;                                                  \
 842         if (!(condition))                                               \
 843                 __ret = __wait_event_interruptible_lock_irq(wq,         \
 844                                                 condition, lock, cmd);  \
 845         __ret;                                                          \
 846 })
 847
 848 /**
 849  * wait_event_interruptible_lock_irq - sleep until a condition gets true.
 850  *              The condition is checked under the lock. This is expected
 851  *              to be called with the lock taken.
 852  * @wq: the waitqueue to wait on
 853  * @condition: a C expression for the event to wait for
 854  * @lock: a locked spinlock_t, which will be released before schedule()
 855  *        and reacquired afterwards.
 856  *
 857  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 858  * @condition evaluates to true or signal is received. The @condition is
 859  * checked each time the waitqueue @wq is woken up.
 860  *
 861  * wake_up() has to be called after changing any variable that could
 862  * change the result of the wait condition.
 863  *
 864  * This is supposed to be called while holding the lock. The lock is
 865  * dropped before going to sleep and is reacquired afterwards.
 866  *
 867  * The macro will return -ERESTARTSYS if it was interrupted by a signal
 868  * and 0 if @condition evaluated to true.
 869  */
 870 #define wait_event_interruptible_lock_irq(wq, condition, lock)          \
 871 ({                                                                      \
 872         int __ret = 0;                                                  \
 873         if (!(condition))                                               \
 874                 __ret = __wait_event_interruptible_lock_irq(wq,         \
 875                                                 condition, lock,);      \
 876         __ret;                                                          \
 877 })
 878
 879 #define __wait_event_interruptible_lock_irq_timeout(wq, condition,      \
 880                                                     lock, timeout)      \
 881         ___wait_event(wq, ___wait_cond_timeout(condition),              \
 882                       TASK_INTERRUPTIBLE, 0, timeout,                   \
 883                       spin_unlock_irq(&lock);                           \
 884                       __ret = schedule_timeout(__ret);                  \
 885                       spin_lock_irq(&lock));
 886
 887 /**
 888  * wait_event_interruptible_lock_irq_timeout - sleep until a condition gets
 889  *              true or a timeout elapses. The condition is checked under
 890  *              the lock. This is expected to be called with the lock taken.
 891  * @wq: the waitqueue to wait on
 892  * @condition: a C expression for the event to wait for
 893  * @lock: a locked spinlock_t, which will be released before schedule()
 894  *        and reacquired afterwards.
 895  * @timeout: timeout, in jiffies
 896  *
 897  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 898  * @condition evaluates to true or signal is received. The @condition is
 899  * checked each time the waitqueue @wq is woken up.
 900  *
 901  * wake_up() has to be called after changing any variable that could
 902  * change the result of the wait condition.
 903  *
 904  * This is supposed to be called while holding the lock. The lock is
 905  * dropped before going to sleep and is reacquired afterwards.
 906  *
 907  * The function returns 0 if the @timeout elapsed, -ERESTARTSYS if it
 908  * was interrupted by a signal, and the remaining jiffies otherwise
 909  * if the condition evaluated to true before the timeout elapsed.
 910  */
 911 #define wait_event_interruptible_lock_irq_timeout(wq, condition, lock,  \
 912                                                   timeout)              \
 913 ({                                                                      \
 914         long __ret = timeout;                                           \
 915         if (!___wait_cond_timeout(condition))                           \
 916                 __ret = __wait_event_interruptible_lock_irq_timeout(    \
 917                                         wq, condition, lock, timeout);  \
 918         __ret;                                                          \
 919 })
 920
 921 /*
 922  * Waitqueues which are removed from the waitqueue_head at wakeup time
 923  */
 924 void prepare_to_wait(wait_queue_head_t *q, wait_queue_t *wait, int state);
 925 void prepare_to_wait_exclusive(wait_queue_head_t *q, wait_queue_t *wait, int state);
 926 long prepare_to_wait_event(wait_queue_head_t *q, wait_queue_t *wait, int state);
 927 void finish_wait(wait_queue_head_t *q, wait_queue_t *wait);
 928 void abort_exclusive_wait(wait_queue_head_t *q, wait_queue_t *wait, unsigned int mode, void *key);
 929 long wait_woken(wait_queue_t *wait, unsigned mode, long timeout);
 930 int woken_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 931 int autoremove_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 932 int wake_bit_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 933
 934 #define DEFINE_WAIT_FUNC(name, function)                                \
 935         wait_queue_t name = {                                           \
 936                 .private        = current,                              \
 937                 .func           = function,                             \
 938                 .task_list      = LIST_HEAD_INIT((name).task_list),     \
 939         }
 940
 941 #define DEFINE_WAIT(name) DEFINE_WAIT_FUNC(name, autoremove_wake_function)
 942
 943 #define DEFINE_WAIT_BIT(name, word, bit)                                \
 944         struct wait_bit_queue name = {                                  \
 945                 .key = __WAIT_BIT_KEY_INITIALIZER(word, bit),           \
 946                 .wait   = {                                             \
 947                         .private        = current,                      \
 948                         .func           = wake_bit_function,            \
 949                         .task_list      =                               \
 950                                 LIST_HEAD_INIT((name).wait.task_list),  \
 951                 },                                                      \
 952         }
 953
 954 #define init_wait(wait)                                                 \
 955         do {                                                            \
 956                 (wait)->private = current;                              \
 957                 (wait)->func = autoremove_wake_function;                \
 958                 INIT_LIST_HEAD(&(wait)->task_list);                     \
 959                 (wait)->flags = 0;                                      \
 960         } while (0)
 961
 962
 963 extern int bit_wait(struct wait_bit_key *);
 964 extern int bit_wait_io(struct wait_bit_key *);
 965 extern int bit_wait_timeout(struct wait_bit_key *);
 966 extern int bit_wait_io_timeout(struct wait_bit_key *);
 967
 968 /**
 969  * wait_on_bit - wait for a bit to be cleared
 970  * @word: the word being waited on, a kernel virtual address
 971  * @bit: the bit of the word being waited on
 972  * @mode: the task state to sleep in
 973  *
 974  * There is a standard hashed waitqueue table for generic use. This
 975  * is the part of the hashtable's accessor API that waits on a bit.
 976  * For instance, if one were to have waiters on a bitflag, one would
 977  * call wait_on_bit() in threads waiting for the bit to clear.
 978  * One uses wait_on_bit() where one is waiting for the bit to clear,
 979  * but has no intention of setting it.
 980  * Returned value will be zero if the bit was cleared, or non-zero
 981  * if the process received a signal and the mode permitted wakeup
 982  * on that signal.
 983  */
 984 static inline int
 985 wait_on_bit(unsigned long *word, int bit, unsigned mode)
 986 {
 987         might_sleep();
 988         if (!test_bit(bit, word))
 989                 return 0;
 990         return out_of_line_wait_on_bit(word, bit,
 991                                        bit_wait,
 992                                        mode);
 993 }
 994
 995 /**
 996  * wait_on_bit_io - wait for a bit to be cleared
 997  * @word: the word being waited on, a kernel virtual address
 998  * @bit: the bit of the word being waited on
 999  * @mode: the task state to sleep in
1000  *
1001  * Use the standard hashed waitqueue table to wait for a bit
1002  * to be cleared.  This is similar to wait_on_bit(), but calls
1003  * io_schedule() instead of schedule() for the actual waiting.
1004  *
1005  * Returned value will be zero if the bit was cleared, or non-zero
1006  * if the process received a signal and the mode permitted wakeup
1007  * on that signal.
1008  */
1009 static inline int
1010 wait_on_bit_io(unsigned long *word, int bit, unsigned mode)
1011 {
1012         might_sleep();
1013         if (!test_bit(bit, word))
1014                 return 0;
1015         return out_of_line_wait_on_bit(word, bit,
1016                                        bit_wait_io,
1017                                        mode);
1018 }
1019
1020 /**
1021  * wait_on_bit_timeout - wait for a bit to be cleared or a timeout elapses
1022  * @word: the word being waited on, a kernel virtual address
1023  * @bit: the bit of the word being waited on
1024  * @mode: the task state to sleep in
1025  * @timeout: timeout, in jiffies
1026  *
1027  * Use the standard hashed waitqueue table to wait for a bit
1028  * to be cleared. This is similar to wait_on_bit(), except also takes a
1029  * timeout parameter.
1030  *
1031  * Returned value will be zero if the bit was cleared before the
1032  * @timeout elapsed, or non-zero if the @timeout elapsed or process
1033  * received a signal and the mode permitted wakeup on that signal.
1034  */
1035 static inline int
1036 wait_on_bit_timeout(unsigned long *word, int bit, unsigned mode,
1037                     unsigned long timeout)
1038 {
1039         might_sleep();
1040         if (!test_bit(bit, word))
1041                 return 0;
1042         return out_of_line_wait_on_bit_timeout(word, bit,
1043                                                bit_wait_timeout,
1044                                                mode, timeout);
1045 }
1046
1047 /**
1048  * wait_on_bit_action - wait for a bit to be cleared
1049  * @word: the word being waited on, a kernel virtual address
1050  * @bit: the bit of the word being waited on
1051  * @action: the function used to sleep, which may take special actions
1052  * @mode: the task state to sleep in
1053  *
1054  * Use the standard hashed waitqueue table to wait for a bit
1055  * to be cleared, and allow the waiting action to be specified.
1056  * This is like wait_on_bit() but allows fine control of how the waiting
1057  * is done.
1058  *
1059  * Returned value will be zero if the bit was cleared, or non-zero
1060  * if the process received a signal and the mode permitted wakeup
1061  * on that signal.
1062  */
1063 static inline int
1064 wait_on_bit_action(unsigned long *word, int bit, wait_bit_action_f *action,
1065                    unsigned mode)
1066 {
1067         might_sleep();
1068         if (!test_bit(bit, word))
1069                 return 0;
1070         return out_of_line_wait_on_bit(word, bit, action, mode);
1071 }
1072
1073 /**
1074  * wait_on_bit_lock - wait for a bit to be cleared, when wanting to set it
1075  * @word: the word being waited on, a kernel virtual address
1076  * @bit: the bit of the word being waited on
1077  * @mode: the task state to sleep in
1078  *
1079  * There is a standard hashed waitqueue table for generic use. This
1080  * is the part of the hashtable's accessor API that waits on a bit
1081  * when one intends to set it, for instance, trying to lock bitflags.
1082  * For instance, if one were to have waiters trying to set bitflag
1083  * and waiting for it to clear before setting it, one would call
1084  * wait_on_bit() in threads waiting to be able to set the bit.
1085  * One uses wait_on_bit_lock() where one is waiting for the bit to
1086  * clear with the intention of setting it, and when done, clearing it.
1087  *
1088  * Returns zero if the bit was (eventually) found to be clear and was
1089  * set.  Returns non-zero if a signal was delivered to the process and
1090  * the @mode allows that signal to wake the process.
1091  */
1092 static inline int
1093 wait_on_bit_lock(unsigned long *word, int bit, unsigned mode)
1094 {
1095         might_sleep();
1096         if (!test_and_set_bit(bit, word))
1097                 return 0;
1098         return out_of_line_wait_on_bit_lock(word, bit, bit_wait, mode);
1099 }
1100
1101 /**
1102  * wait_on_bit_lock_io - wait for a bit to be cleared, when wanting to set it
1103  * @word: the word being waited on, a kernel virtual address
1104  * @bit: the bit of the word being waited on
1105  * @mode: the task state to sleep in
1106  *
1107  * Use the standard hashed waitqueue table to wait for a bit
1108  * to be cleared and then to atomically set it.  This is similar
1109  * to wait_on_bit(), but calls io_schedule() instead of schedule()
1110  * for the actual waiting.
1111  *
1112  * Returns zero if the bit was (eventually) found to be clear and was
1113  * set.  Returns non-zero if a signal was delivered to the process and
1114  * the @mode allows that signal to wake the process.
1115  */
1116 static inline int
1117 wait_on_bit_lock_io(unsigned long *word, int bit, unsigned mode)
1118 {
1119         might_sleep();
1120         if (!test_and_set_bit(bit, word))
1121                 return 0;
1122         return out_of_line_wait_on_bit_lock(word, bit, bit_wait_io, mode);
1123 }
1124
1125 /**
1126  * wait_on_bit_lock_action - wait for a bit to be cleared, when wanting to set it
1127  * @word: the word being waited on, a kernel virtual address
1128  * @bit: the bit of the word being waited on
1129  * @action: the function used to sleep, which may take special actions
1130  * @mode: the task state to sleep in
1131  *
1132  * Use the standard hashed waitqueue table to wait for a bit
1133  * to be cleared and then to set it, and allow the waiting action
1134  * to be specified.
1135  * This is like wait_on_bit() but allows fine control of how the waiting
1136  * is done.
1137  *
1138  * Returns zero if the bit was (eventually) found to be clear and was
1139  * set.  Returns non-zero if a signal was delivered to the process and
1140  * the @mode allows that signal to wake the process.
1141  */
1142 static inline int
1143 wait_on_bit_lock_action(unsigned long *word, int bit, wait_bit_action_f *action,
1144                         unsigned mode)
1145 {
1146         might_sleep();
1147         if (!test_and_set_bit(bit, word))
1148                 return 0;
1149         return out_of_line_wait_on_bit_lock(word, bit, action, mode);
1150 }
1151
1152 /**
1153  * wait_on_atomic_t - Wait for an atomic_t to become 0
1154  * @val: The atomic value being waited on, a kernel virtual address
1155  * @action: the function used to sleep, which may take special actions
1156  * @mode: the task state to sleep in
1157  *
1158  * Wait for an atomic_t to become 0.  We abuse the bit-wait waitqueue table for
1159  * the purpose of getting a waitqueue, but we set the key to a bit number
1160  * outside of the target 'word'.
1161  */
1162 static inline
1163 int wait_on_atomic_t(atomic_t *val, int (*action)(atomic_t *), unsigned mode)
1164 {
1165         might_sleep();
1166         if (atomic_read(val) == 0)
1167                 return 0;
1168         return out_of_line_wait_on_atomic_t(val, action, mode);
1169 }
1170
1171 #endif /* _LINUX_WAIT_H */