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, int nr,
 151                           void *key);
 152 void __wake_up_sync_key(wait_queue_head_t *q, unsigned int mode, int nr, void *key);
 153 void __wake_up_locked(wait_queue_head_t *q, unsigned int mode, int nr);
 154 void __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr);
 155 void __wake_up_bit(wait_queue_head_t *, void *, int);
 156 int __wait_on_bit(wait_queue_head_t *, struct wait_bit_queue *, wait_bit_action_f *, unsigned);
 157 int __wait_on_bit_lock(wait_queue_head_t *, struct wait_bit_queue *, wait_bit_action_f *, unsigned);
 158 void wake_up_bit(void *, int);
 159 void wake_up_atomic_t(atomic_t *);
 160 int out_of_line_wait_on_bit(void *, int, wait_bit_action_f *, unsigned);
 161 int out_of_line_wait_on_bit_timeout(void *, int, wait_bit_action_f *, unsigned, unsigned long);
 162 int out_of_line_wait_on_bit_lock(void *, int, wait_bit_action_f *, unsigned);
 163 int out_of_line_wait_on_atomic_t(atomic_t *, int (*)(atomic_t *), unsigned);
 164 wait_queue_head_t *bit_waitqueue(void *, int);
 165
 166 #define wake_up(x)                      __wake_up(x, TASK_NORMAL, 1, NULL)
 167 #define wake_up_nr(x, nr)               __wake_up(x, TASK_NORMAL, nr, NULL)
 168 #define wake_up_all(x)                  __wake_up(x, TASK_NORMAL, 0, NULL)
 169 #define wake_up_locked(x)               __wake_up_locked((x), TASK_NORMAL, 1)
 170 #define wake_up_all_locked(x)           __wake_up_locked((x), TASK_NORMAL, 0)
 171
 172 #define wake_up_interruptible(x)        __wake_up(x, TASK_INTERRUPTIBLE, 1, NULL)
 173 #define wake_up_interruptible_nr(x, nr) __wake_up(x, TASK_INTERRUPTIBLE, nr, NULL)
 174 #define wake_up_interruptible_all(x)    __wake_up(x, TASK_INTERRUPTIBLE, 0, NULL)
 175 #define wake_up_interruptible_sync(x)   __wake_up_sync((x), TASK_INTERRUPTIBLE, 1)
 176
 177 /*
 178  * Wakeup macros to be used to report events to the targets.
 179  */
 180 #define wake_up_poll(x, m)                                              \
 181         __wake_up(x, TASK_NORMAL, 1, (void *) (m))
 182 #define wake_up_locked_poll(x, m)                                       \
 183         __wake_up_locked_key((x), TASK_NORMAL, 1, (void *) (m))
 184 #define wake_up_interruptible_poll(x, m)                                \
 185         __wake_up(x, TASK_INTERRUPTIBLE, 1, (void *) (m))
 186 #define wake_up_interruptible_sync_poll(x, m)                           \
 187         __wake_up_sync_key((x), TASK_INTERRUPTIBLE, 1, (void *) (m))
 188
 189 #define ___wait_cond_timeout(condition)                                 \
 190 ({                                                                      \
 191         bool __cond = (condition);                                      \
 192         if (__cond && !__ret)                                           \
 193                 __ret = 1;                                              \
 194         __cond || !__ret;                                               \
 195 })
 196
 197 #define ___wait_is_interruptible(state)                                 \
 198         (!__builtin_constant_p(state) ||                                \
 199                 state == TASK_INTERRUPTIBLE || state == TASK_KILLABLE)  \
 200
 201 /*
 202  * The below macro ___wait_event() has an explicit shadow of the __ret
 203  * variable when used from the wait_event_*() macros.
 204  *
 205  * This is so that both can use the ___wait_cond_timeout() construct
 206  * to wrap the condition.
 207  *
 208  * The type inconsistency of the wait_event_*() __ret variable is also
 209  * on purpose; we use long where we can return timeout values and int
 210  * otherwise.
 211  */
 212
 213 #define ___wait_event(wq, condition, state, exclusive, ret, cmd)        \
 214 ({                                                                      \
 215         __label__ __out;                                                \
 216         wait_queue_t __wait;                                            \
 217         long __ret = ret;       /* explicit shadow */                   \
 218                                                                         \
 219         INIT_LIST_HEAD(&__wait.task_list);                              \
 220         if (exclusive)                                                  \
 221                 __wait.flags = WQ_FLAG_EXCLUSIVE;                       \
 222         else                                                            \
 223                 __wait.flags = 0;                                       \
 224                                                                         \
 225         for (;;) {                                                      \
 226                 long __int = prepare_to_wait_event(&wq, &__wait, state);\
 227                                                                         \
 228                 if (condition)                                          \
 229                         break;                                          \
 230                                                                         \
 231                 if (___wait_is_interruptible(state) && __int) {         \
 232                         __ret = __int;                                  \
 233                         if (exclusive) {                                \
 234                                 abort_exclusive_wait(&wq, &__wait,      \
 235                                                      state, NULL);      \
 236                                 goto __out;                             \
 237                         }                                               \
 238                         break;                                          \
 239                 }                                                       \
 240                                                                         \
 241                 cmd;                                                    \
 242         }                                                               \
 243         finish_wait(&wq, &__wait);                                      \
 244 __out:  __ret;                                                          \
 245 })
 246
 247 #define __wait_event(wq, condition)                                     \
 248         (void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0, 0,  \
 249                             schedule())
 250
 251 /**
 252  * wait_event - sleep until a condition gets true
 253  * @wq: the waitqueue to wait on
 254  * @condition: a C expression for the event to wait for
 255  *
 256  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 257  * @condition evaluates to true. The @condition is checked each time
 258  * the waitqueue @wq is woken up.
 259  *
 260  * wake_up() has to be called after changing any variable that could
 261  * change the result of the wait condition.
 262  */
 263 #define wait_event(wq, condition)                                       \
 264 do {                                                                    \
 265         might_sleep();                                                  \
 266         if (condition)                                                  \
 267                 break;                                                  \
 268         __wait_event(wq, condition);                                    \
 269 } while (0)
 270
 271 #define __io_wait_event(wq, condition)                                  \
 272         (void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0, 0,  \
 273                             io_schedule())
 274
 275 /*
 276  * io_wait_event() -- like wait_event() but with io_schedule()
 277  */
 278 #define io_wait_event(wq, condition)                                    \
 279 do {                                                                    \
 280         might_sleep();                                                  \
 281         if (condition)                                                  \
 282                 break;                                                  \
 283         __io_wait_event(wq, condition);                                 \
 284 } while (0)
 285
 286 #define __wait_event_freezable(wq, condition)                           \
 287         ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 0, 0,          \
 288                             schedule(); try_to_freeze())
 289
 290 /**
 291  * wait_event - sleep (or freeze) until a condition gets true
 292  * @wq: the waitqueue to wait on
 293  * @condition: a C expression for the event to wait for
 294  *
 295  * The process is put to sleep (TASK_INTERRUPTIBLE -- so as not to contribute
 296  * to system load) until the @condition evaluates to true. The
 297  * @condition is checked each time the waitqueue @wq is woken up.
 298  *
 299  * wake_up() has to be called after changing any variable that could
 300  * change the result of the wait condition.
 301  */
 302 #define wait_event_freezable(wq, condition)                             \
 303 ({                                                                      \
 304         int __ret = 0;                                                  \
 305         might_sleep();                                                  \
 306         if (!(condition))                                               \
 307                 __ret = __wait_event_freezable(wq, condition);          \
 308         __ret;                                                          \
 309 })
 310
 311 #define __wait_event_timeout(wq, condition, timeout)                    \
 312         ___wait_event(wq, ___wait_cond_timeout(condition),              \
 313                       TASK_UNINTERRUPTIBLE, 0, timeout,                 \
 314                       __ret = schedule_timeout(__ret))
 315
 316 /**
 317  * wait_event_timeout - sleep until a condition gets true or a timeout elapses
 318  * @wq: the waitqueue to wait on
 319  * @condition: a C expression for the event to wait for
 320  * @timeout: timeout, in jiffies
 321  *
 322  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 323  * @condition evaluates to true. The @condition is checked each time
 324  * the waitqueue @wq is woken up.
 325  *
 326  * wake_up() has to be called after changing any variable that could
 327  * change the result of the wait condition.
 328  *
 329  * Returns:
 330  * 0 if the @condition evaluated to %false after the @timeout elapsed,
 331  * 1 if the @condition evaluated to %true after the @timeout elapsed,
 332  * or the remaining jiffies (at least 1) if the @condition evaluated
 333  * to %true before the @timeout elapsed.
 334  */
 335 #define wait_event_timeout(wq, condition, timeout)                      \
 336 ({                                                                      \
 337         long __ret = timeout;                                           \
 338         might_sleep();                                                  \
 339         if (!___wait_cond_timeout(condition))                           \
 340                 __ret = __wait_event_timeout(wq, condition, timeout);   \
 341         __ret;                                                          \
 342 })
 343
 344 #define __wait_event_freezable_timeout(wq, condition, timeout)          \
 345         ___wait_event(wq, ___wait_cond_timeout(condition),              \
 346                       TASK_INTERRUPTIBLE, 0, timeout,                   \
 347                       __ret = schedule_timeout(__ret); try_to_freeze())
 348
 349 /*
 350  * like wait_event_timeout() -- except it uses TASK_INTERRUPTIBLE to avoid
 351  * increasing load and is freezable.
 352  */
 353 #define wait_event_freezable_timeout(wq, condition, timeout)            \
 354 ({                                                                      \
 355         long __ret = timeout;                                           \
 356         might_sleep();                                                  \
 357         if (!___wait_cond_timeout(condition))                           \
 358                 __ret = __wait_event_freezable_timeout(wq, condition, timeout); \
 359         __ret;                                                          \
 360 })
 361
 362 #define __wait_event_exclusive_cmd(wq, condition, cmd1, cmd2)           \
 363         (void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 1, 0,  \
 364                             cmd1; schedule(); cmd2)
 365 /*
 366  * Just like wait_event_cmd(), except it sets exclusive flag
 367  */
 368 #define wait_event_exclusive_cmd(wq, condition, cmd1, cmd2)             \
 369 do {                                                                    \
 370         if (condition)                                                  \
 371                 break;                                                  \
 372         __wait_event_exclusive_cmd(wq, condition, cmd1, cmd2);          \
 373 } while (0)
 374
 375 #define __wait_event_cmd(wq, condition, cmd1, cmd2)                     \
 376         (void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0, 0,  \
 377                             cmd1; schedule(); cmd2)
 378
 379 /**
 380  * wait_event_cmd - sleep until a condition gets true
 381  * @wq: the waitqueue to wait on
 382  * @condition: a C expression for the event to wait for
 383  * @cmd1: the command will be executed before sleep
 384  * @cmd2: the command will be executed after sleep
 385  *
 386  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 387  * @condition evaluates to true. The @condition is checked each time
 388  * the waitqueue @wq is woken up.
 389  *
 390  * wake_up() has to be called after changing any variable that could
 391  * change the result of the wait condition.
 392  */
 393 #define wait_event_cmd(wq, condition, cmd1, cmd2)                       \
 394 do {                                                                    \
 395         if (condition)                                                  \
 396                 break;                                                  \
 397         __wait_event_cmd(wq, condition, cmd1, cmd2);                    \
 398 } while (0)
 399
 400 #define __wait_event_interruptible(wq, condition)                       \
 401         ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 0, 0,          \
 402                       schedule())
 403
 404 /**
 405  * wait_event_interruptible - sleep until a condition gets true
 406  * @wq: the waitqueue to wait on
 407  * @condition: a C expression for the event to wait for
 408  *
 409  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 410  * @condition evaluates to true or a signal is received.
 411  * The @condition is checked each time the waitqueue @wq is woken up.
 412  *
 413  * wake_up() has to be called after changing any variable that could
 414  * change the result of the wait condition.
 415  *
 416  * The function will return -ERESTARTSYS if it was interrupted by a
 417  * signal and 0 if @condition evaluated to true.
 418  */
 419 #define wait_event_interruptible(wq, condition)                         \
 420 ({                                                                      \
 421         int __ret = 0;                                                  \
 422         might_sleep();                                                  \
 423         if (!(condition))                                               \
 424                 __ret = __wait_event_interruptible(wq, condition);      \
 425         __ret;                                                          \
 426 })
 427
 428 #define __wait_event_interruptible_timeout(wq, condition, timeout)      \
 429         ___wait_event(wq, ___wait_cond_timeout(condition),              \
 430                       TASK_INTERRUPTIBLE, 0, timeout,                   \
 431                       __ret = schedule_timeout(__ret))
 432
 433 /**
 434  * wait_event_interruptible_timeout - sleep until a condition gets true or a timeout elapses
 435  * @wq: the waitqueue to wait on
 436  * @condition: a C expression for the event to wait for
 437  * @timeout: timeout, in jiffies
 438  *
 439  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 440  * @condition evaluates to true or a signal is received.
 441  * The @condition is checked each time the waitqueue @wq is woken up.
 442  *
 443  * wake_up() has to be called after changing any variable that could
 444  * change the result of the wait condition.
 445  *
 446  * Returns:
 447  * 0 if the @condition evaluated to %false after the @timeout elapsed,
 448  * 1 if the @condition evaluated to %true after the @timeout elapsed,
 449  * the remaining jiffies (at least 1) if the @condition evaluated
 450  * to %true before the @timeout elapsed, or -%ERESTARTSYS if it was
 451  * interrupted by a signal.
 452  */
 453 #define wait_event_interruptible_timeout(wq, condition, timeout)        \
 454 ({                                                                      \
 455         long __ret = timeout;                                           \
 456         might_sleep();                                                  \
 457         if (!___wait_cond_timeout(condition))                           \
 458                 __ret = __wait_event_interruptible_timeout(wq,          \
 459                                                 condition, timeout);    \
 460         __ret;                                                          \
 461 })
 462
 463 #define __wait_event_hrtimeout(wq, condition, timeout, state)           \
 464 ({                                                                      \
 465         int __ret = 0;                                                  \
 466         struct hrtimer_sleeper __t;                                     \
 467                                                                         \
 468         hrtimer_init_on_stack(&__t.timer, CLOCK_MONOTONIC,              \
 469                               HRTIMER_MODE_REL);                        \
 470         hrtimer_init_sleeper(&__t, current);                            \
 471         if ((timeout).tv64 != KTIME_MAX)                                \
 472                 hrtimer_start_range_ns(&__t.timer, timeout,             \
 473                                        current->timer_slack_ns,         \
 474                                        HRTIMER_MODE_REL);               \
 475                                                                         \
 476         __ret = ___wait_event(wq, condition, state, 0, 0,               \
 477                 if (!__t.task) {                                        \
 478                         __ret = -ETIME;                                 \
 479                         break;                                          \
 480                 }                                                       \
 481                 schedule());                                            \
 482                                                                         \
 483         hrtimer_cancel(&__t.timer);                                     \
 484         destroy_hrtimer_on_stack(&__t.timer);                           \
 485         __ret;                                                          \
 486 })
 487
 488 /**
 489  * wait_event_hrtimeout - sleep until a condition gets true or a timeout elapses
 490  * @wq: the waitqueue to wait on
 491  * @condition: a C expression for the event to wait for
 492  * @timeout: timeout, as a ktime_t
 493  *
 494  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 495  * @condition evaluates to true or a signal is received.
 496  * The @condition is checked each time the waitqueue @wq is woken up.
 497  *
 498  * wake_up() has to be called after changing any variable that could
 499  * change the result of the wait condition.
 500  *
 501  * The function returns 0 if @condition became true, or -ETIME if the timeout
 502  * elapsed.
 503  */
 504 #define wait_event_hrtimeout(wq, condition, timeout)                    \
 505 ({                                                                      \
 506         int __ret = 0;                                                  \
 507         might_sleep();                                                  \
 508         if (!(condition))                                               \
 509                 __ret = __wait_event_hrtimeout(wq, condition, timeout,  \
 510                                                TASK_UNINTERRUPTIBLE);   \
 511         __ret;                                                          \
 512 })
 513
 514 /**
 515  * wait_event_interruptible_hrtimeout - sleep until a condition gets true or a timeout elapses
 516  * @wq: the waitqueue to wait on
 517  * @condition: a C expression for the event to wait for
 518  * @timeout: timeout, as a ktime_t
 519  *
 520  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 521  * @condition evaluates to true or a signal is received.
 522  * The @condition is checked each time the waitqueue @wq is woken up.
 523  *
 524  * wake_up() has to be called after changing any variable that could
 525  * change the result of the wait condition.
 526  *
 527  * The function returns 0 if @condition became true, -ERESTARTSYS if it was
 528  * interrupted by a signal, or -ETIME if the timeout elapsed.
 529  */
 530 #define wait_event_interruptible_hrtimeout(wq, condition, timeout)      \
 531 ({                                                                      \
 532         long __ret = 0;                                                 \
 533         might_sleep();                                                  \
 534         if (!(condition))                                               \
 535                 __ret = __wait_event_hrtimeout(wq, condition, timeout,  \
 536                                                TASK_INTERRUPTIBLE);     \
 537         __ret;                                                          \
 538 })
 539
 540 #define __wait_event_interruptible_exclusive(wq, condition)             \
 541         ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 1, 0,          \
 542                       schedule())
 543
 544 #define wait_event_interruptible_exclusive(wq, condition)               \
 545 ({                                                                      \
 546         int __ret = 0;                                                  \
 547         might_sleep();                                                  \
 548         if (!(condition))                                               \
 549                 __ret = __wait_event_interruptible_exclusive(wq, condition);\
 550         __ret;                                                          \
 551 })
 552
 553
 554 #define __wait_event_freezable_exclusive(wq, condition)                 \
 555         ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 1, 0,          \
 556                         schedule(); try_to_freeze())
 557
 558 #define wait_event_freezable_exclusive(wq, condition)                   \
 559 ({                                                                      \
 560         int __ret = 0;                                                  \
 561         might_sleep();                                                  \
 562         if (!(condition))                                               \
 563                 __ret = __wait_event_freezable_exclusive(wq, condition);\
 564         __ret;                                                          \
 565 })
 566
 567
 568 #define __wait_event_interruptible_locked(wq, condition, exclusive, irq) \
 569 ({                                                                      \
 570         int __ret = 0;                                                  \
 571         DEFINE_WAIT(__wait);                                            \
 572         if (exclusive)                                                  \
 573                 __wait.flags |= WQ_FLAG_EXCLUSIVE;                      \
 574         do {                                                            \
 575                 if (likely(list_empty(&__wait.task_list)))              \
 576                         __add_wait_queue_tail(&(wq), &__wait);          \
 577                 set_current_state(TASK_INTERRUPTIBLE);                  \
 578                 if (signal_pending(current)) {                          \
 579                         __ret = -ERESTARTSYS;                           \
 580                         break;                                          \
 581                 }                                                       \
 582                 if (irq)                                                \
 583                         spin_unlock_irq(&(wq).lock);                    \
 584                 else                                                    \
 585                         spin_unlock(&(wq).lock);                        \
 586                 schedule();                                             \
 587                 if (irq)                                                \
 588                         spin_lock_irq(&(wq).lock);                      \
 589                 else                                                    \
 590                         spin_lock(&(wq).lock);                          \
 591         } while (!(condition));                                         \
 592         __remove_wait_queue(&(wq), &__wait);                            \
 593         __set_current_state(TASK_RUNNING);                              \
 594         __ret;                                                          \
 595 })
 596
 597
 598 /**
 599  * wait_event_interruptible_locked - sleep until a condition gets true
 600  * @wq: the waitqueue to wait on
 601  * @condition: a C expression for the event to wait for
 602  *
 603  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 604  * @condition evaluates to true or a signal is received.
 605  * The @condition is checked each time the waitqueue @wq is woken up.
 606  *
 607  * It must be called with wq.lock being held.  This spinlock is
 608  * unlocked while sleeping but @condition testing is done while lock
 609  * is held and when this macro exits the lock is held.
 610  *
 611  * The lock is locked/unlocked using spin_lock()/spin_unlock()
 612  * functions which must match the way they are locked/unlocked outside
 613  * of this macro.
 614  *
 615  * wake_up_locked() has to be called after changing any variable that could
 616  * change the result of the wait condition.
 617  *
 618  * The function will return -ERESTARTSYS if it was interrupted by a
 619  * signal and 0 if @condition evaluated to true.
 620  */
 621 #define wait_event_interruptible_locked(wq, condition)                  \
 622         ((condition)                                                    \
 623          ? 0 : __wait_event_interruptible_locked(wq, condition, 0, 0))
 624
 625 /**
 626  * wait_event_interruptible_locked_irq - sleep until a condition gets true
 627  * @wq: the waitqueue to wait on
 628  * @condition: a C expression for the event to wait for
 629  *
 630  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 631  * @condition evaluates to true or a signal is received.
 632  * The @condition is checked each time the waitqueue @wq is woken up.
 633  *
 634  * It must be called with wq.lock being held.  This spinlock is
 635  * unlocked while sleeping but @condition testing is done while lock
 636  * is held and when this macro exits the lock is held.
 637  *
 638  * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq()
 639  * functions which must match the way they are locked/unlocked outside
 640  * of this macro.
 641  *
 642  * wake_up_locked() has to be called after changing any variable that could
 643  * change the result of the wait condition.
 644  *
 645  * The function will return -ERESTARTSYS if it was interrupted by a
 646  * signal and 0 if @condition evaluated to true.
 647  */
 648 #define wait_event_interruptible_locked_irq(wq, condition)              \
 649         ((condition)                                                    \
 650          ? 0 : __wait_event_interruptible_locked(wq, condition, 0, 1))
 651
 652 /**
 653  * wait_event_interruptible_exclusive_locked - sleep exclusively until a condition gets true
 654  * @wq: the waitqueue to wait on
 655  * @condition: a C expression for the event to wait for
 656  *
 657  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 658  * @condition evaluates to true or a signal is received.
 659  * The @condition is checked each time the waitqueue @wq is woken up.
 660  *
 661  * It must be called with wq.lock being held.  This spinlock is
 662  * unlocked while sleeping but @condition testing is done while lock
 663  * is held and when this macro exits the lock is held.
 664  *
 665  * The lock is locked/unlocked using spin_lock()/spin_unlock()
 666  * functions which must match the way they are locked/unlocked outside
 667  * of this macro.
 668  *
 669  * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
 670  * set thus when other process waits process on the list if this
 671  * process is awaken further processes are not considered.
 672  *
 673  * wake_up_locked() has to be called after changing any variable that could
 674  * change the result of the wait condition.
 675  *
 676  * The function will return -ERESTARTSYS if it was interrupted by a
 677  * signal and 0 if @condition evaluated to true.
 678  */
 679 #define wait_event_interruptible_exclusive_locked(wq, condition)        \
 680         ((condition)                                                    \
 681          ? 0 : __wait_event_interruptible_locked(wq, condition, 1, 0))
 682
 683 /**
 684  * wait_event_interruptible_exclusive_locked_irq - sleep until a condition gets true
 685  * @wq: the waitqueue to wait on
 686  * @condition: a C expression for the event to wait for
 687  *
 688  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 689  * @condition evaluates to true or a signal is received.
 690  * The @condition is checked each time the waitqueue @wq is woken up.
 691  *
 692  * It must be called with wq.lock being held.  This spinlock is
 693  * unlocked while sleeping but @condition testing is done while lock
 694  * is held and when this macro exits the lock is held.
 695  *
 696  * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq()
 697  * functions which must match the way they are locked/unlocked outside
 698  * of this macro.
 699  *
 700  * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
 701  * set thus when other process waits process on the list if this
 702  * process is awaken further processes are not considered.
 703  *
 704  * wake_up_locked() has to be called after changing any variable that could
 705  * change the result of the wait condition.
 706  *
 707  * The function will return -ERESTARTSYS if it was interrupted by a
 708  * signal and 0 if @condition evaluated to true.
 709  */
 710 #define wait_event_interruptible_exclusive_locked_irq(wq, condition)    \
 711         ((condition)                                                    \
 712          ? 0 : __wait_event_interruptible_locked(wq, condition, 1, 1))
 713
 714
 715 #define __wait_event_killable(wq, condition)                            \
 716         ___wait_event(wq, condition, TASK_KILLABLE, 0, 0, schedule())
 717
 718 /**
 719  * wait_event_killable - sleep until a condition gets true
 720  * @wq: the waitqueue to wait on
 721  * @condition: a C expression for the event to wait for
 722  *
 723  * The process is put to sleep (TASK_KILLABLE) until the
 724  * @condition evaluates to true or a signal is received.
 725  * The @condition is checked each time the waitqueue @wq is woken up.
 726  *
 727  * wake_up() has to be called after changing any variable that could
 728  * change the result of the wait condition.
 729  *
 730  * The function will return -ERESTARTSYS if it was interrupted by a
 731  * signal and 0 if @condition evaluated to true.
 732  */
 733 #define wait_event_killable(wq, condition)                              \
 734 ({                                                                      \
 735         int __ret = 0;                                                  \
 736         might_sleep();                                                  \
 737         if (!(condition))                                               \
 738                 __ret = __wait_event_killable(wq, condition);           \
 739         __ret;                                                          \
 740 })
 741
 742
 743 #define __wait_event_lock_irq(wq, condition, lock, cmd)                 \
 744         (void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0, 0,  \
 745                             spin_unlock_irq(&lock);                     \
 746                             cmd;                                        \
 747                             schedule();                                 \
 748                             spin_lock_irq(&lock))
 749
 750 /**
 751  * wait_event_lock_irq_cmd - sleep until a condition gets true. The
 752  *                           condition is checked under the lock. This
 753  *                           is expected to be called with the lock
 754  *                           taken.
 755  * @wq: the waitqueue to wait on
 756  * @condition: a C expression for the event to wait for
 757  * @lock: a locked spinlock_t, which will be released before cmd
 758  *        and schedule() and reacquired afterwards.
 759  * @cmd: a command which is invoked outside the critical section before
 760  *       sleep
 761  *
 762  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 763  * @condition evaluates to true. The @condition is checked each time
 764  * the waitqueue @wq is woken up.
 765  *
 766  * wake_up() has to be called after changing any variable that could
 767  * change the result of the wait condition.
 768  *
 769  * This is supposed to be called while holding the lock. The lock is
 770  * dropped before invoking the cmd and going to sleep and is reacquired
 771  * afterwards.
 772  */
 773 #define wait_event_lock_irq_cmd(wq, condition, lock, cmd)               \
 774 do {                                                                    \
 775         if (condition)                                                  \
 776                 break;                                                  \
 777         __wait_event_lock_irq(wq, condition, lock, cmd);                \
 778 } while (0)
 779
 780 /**
 781  * wait_event_lock_irq - sleep until a condition gets true. The
 782  *                       condition is checked under the lock. This
 783  *                       is expected to be called with the lock
 784  *                       taken.
 785  * @wq: the waitqueue to wait on
 786  * @condition: a C expression for the event to wait for
 787  * @lock: a locked spinlock_t, which will be released before schedule()
 788  *        and reacquired afterwards.
 789  *
 790  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 791  * @condition evaluates to true. The @condition is checked each time
 792  * the waitqueue @wq is woken up.
 793  *
 794  * wake_up() has to be called after changing any variable that could
 795  * change the result of the wait condition.
 796  *
 797  * This is supposed to be called while holding the lock. The lock is
 798  * dropped before going to sleep and is reacquired afterwards.
 799  */
 800 #define wait_event_lock_irq(wq, condition, lock)                        \
 801 do {                                                                    \
 802         if (condition)                                                  \
 803                 break;                                                  \
 804         __wait_event_lock_irq(wq, condition, lock, );                   \
 805 } while (0)
 806
 807
 808 #define __wait_event_interruptible_lock_irq(wq, condition, lock, cmd)   \
 809         ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 0, 0,          \
 810                       spin_unlock_irq(&lock);                           \
 811                       cmd;                                              \
 812                       schedule();                                       \
 813                       spin_lock_irq(&lock))
 814
 815 /**
 816  * wait_event_interruptible_lock_irq_cmd - sleep until a condition gets true.
 817  *              The condition is checked under the lock. This is expected to
 818  *              be called with the lock taken.
 819  * @wq: the waitqueue to wait on
 820  * @condition: a C expression for the event to wait for
 821  * @lock: a locked spinlock_t, which will be released before cmd and
 822  *        schedule() and reacquired afterwards.
 823  * @cmd: a command which is invoked outside the critical section before
 824  *       sleep
 825  *
 826  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 827  * @condition evaluates to true or a signal is received. The @condition is
 828  * checked each time the waitqueue @wq is woken up.
 829  *
 830  * wake_up() has to be called after changing any variable that could
 831  * change the result of the wait condition.
 832  *
 833  * This is supposed to be called while holding the lock. The lock is
 834  * dropped before invoking the cmd and going to sleep and is reacquired
 835  * afterwards.
 836  *
 837  * The macro will return -ERESTARTSYS if it was interrupted by a signal
 838  * and 0 if @condition evaluated to true.
 839  */
 840 #define wait_event_interruptible_lock_irq_cmd(wq, condition, lock, cmd) \
 841 ({                                                                      \
 842         int __ret = 0;                                                  \
 843         if (!(condition))                                               \
 844                 __ret = __wait_event_interruptible_lock_irq(wq,         \
 845                                                 condition, lock, cmd);  \
 846         __ret;                                                          \
 847 })
 848
 849 /**
 850  * wait_event_interruptible_lock_irq - sleep until a condition gets true.
 851  *              The condition is checked under the lock. This is expected
 852  *              to be called with the lock taken.
 853  * @wq: the waitqueue to wait on
 854  * @condition: a C expression for the event to wait for
 855  * @lock: a locked spinlock_t, which will be released before schedule()
 856  *        and reacquired afterwards.
 857  *
 858  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 859  * @condition evaluates to true or signal is received. The @condition is
 860  * checked each time the waitqueue @wq is woken up.
 861  *
 862  * wake_up() has to be called after changing any variable that could
 863  * change the result of the wait condition.
 864  *
 865  * This is supposed to be called while holding the lock. The lock is
 866  * dropped before going to sleep and is reacquired afterwards.
 867  *
 868  * The macro will return -ERESTARTSYS if it was interrupted by a signal
 869  * and 0 if @condition evaluated to true.
 870  */
 871 #define wait_event_interruptible_lock_irq(wq, condition, lock)          \
 872 ({                                                                      \
 873         int __ret = 0;                                                  \
 874         if (!(condition))                                               \
 875                 __ret = __wait_event_interruptible_lock_irq(wq,         \
 876                                                 condition, lock,);      \
 877         __ret;                                                          \
 878 })
 879
 880 #define __wait_event_interruptible_lock_irq_timeout(wq, condition,      \
 881                                                     lock, timeout)      \
 882         ___wait_event(wq, ___wait_cond_timeout(condition),              \
 883                       TASK_INTERRUPTIBLE, 0, timeout,                   \
 884                       spin_unlock_irq(&lock);                           \
 885                       __ret = schedule_timeout(__ret);                  \
 886                       spin_lock_irq(&lock));
 887
 888 /**
 889  * wait_event_interruptible_lock_irq_timeout - sleep until a condition gets
 890  *              true or a timeout elapses. The condition is checked under
 891  *              the lock. This is expected to be called with the lock taken.
 892  * @wq: the waitqueue to wait on
 893  * @condition: a C expression for the event to wait for
 894  * @lock: a locked spinlock_t, which will be released before schedule()
 895  *        and reacquired afterwards.
 896  * @timeout: timeout, in jiffies
 897  *
 898  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 899  * @condition evaluates to true or signal is received. The @condition is
 900  * checked each time the waitqueue @wq is woken up.
 901  *
 902  * wake_up() has to be called after changing any variable that could
 903  * change the result of the wait condition.
 904  *
 905  * This is supposed to be called while holding the lock. The lock is
 906  * dropped before going to sleep and is reacquired afterwards.
 907  *
 908  * The function returns 0 if the @timeout elapsed, -ERESTARTSYS if it
 909  * was interrupted by a signal, and the remaining jiffies otherwise
 910  * if the condition evaluated to true before the timeout elapsed.
 911  */
 912 #define wait_event_interruptible_lock_irq_timeout(wq, condition, lock,  \
 913                                                   timeout)              \
 914 ({                                                                      \
 915         long __ret = timeout;                                           \
 916         if (!___wait_cond_timeout(condition))                           \
 917                 __ret = __wait_event_interruptible_lock_irq_timeout(    \
 918                                         wq, condition, lock, timeout);  \
 919         __ret;                                                          \
 920 })
 921
 922 /*
 923  * Waitqueues which are removed from the waitqueue_head at wakeup time
 924  */
 925 void prepare_to_wait(wait_queue_head_t *q, wait_queue_t *wait, int state);
 926 void prepare_to_wait_exclusive(wait_queue_head_t *q, wait_queue_t *wait, int state);
 927 long prepare_to_wait_event(wait_queue_head_t *q, wait_queue_t *wait, int state);
 928 void finish_wait(wait_queue_head_t *q, wait_queue_t *wait);
 929 void abort_exclusive_wait(wait_queue_head_t *q, wait_queue_t *wait, unsigned int mode, void *key);
 930 long wait_woken(wait_queue_t *wait, unsigned mode, long timeout);
 931 int woken_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 932 int autoremove_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 933 int wake_bit_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 934
 935 #define DEFINE_WAIT_FUNC(name, function)                                \
 936         wait_queue_t name = {                                           \
 937                 .private        = current,                              \
 938                 .func           = function,                             \
 939                 .task_list      = LIST_HEAD_INIT((name).task_list),     \
 940         }
 941
 942 #define DEFINE_WAIT(name) DEFINE_WAIT_FUNC(name, autoremove_wake_function)
 943
 944 #define DEFINE_WAIT_BIT(name, word, bit)                                \
 945         struct wait_bit_queue name = {                                  \
 946                 .key = __WAIT_BIT_KEY_INITIALIZER(word, bit),           \
 947                 .wait   = {                                             \
 948                         .private        = current,                      \
 949                         .func           = wake_bit_function,            \
 950                         .task_list      =                               \
 951                                 LIST_HEAD_INIT((name).wait.task_list),  \
 952                 },                                                      \
 953         }
 954
 955 #define init_wait(wait)                                                 \
 956         do {                                                            \
 957                 (wait)->private = current;                              \
 958                 (wait)->func = autoremove_wake_function;                \
 959                 INIT_LIST_HEAD(&(wait)->task_list);                     \
 960                 (wait)->flags = 0;                                      \
 961         } while (0)
 962
 963
 964 extern int bit_wait(struct wait_bit_key *);
 965 extern int bit_wait_io(struct wait_bit_key *);
 966 extern int bit_wait_timeout(struct wait_bit_key *);
 967 extern int bit_wait_io_timeout(struct wait_bit_key *);
 968
 969 /**
 970  * wait_on_bit - wait for a bit to be cleared
 971  * @word: the word being waited on, a kernel virtual address
 972  * @bit: the bit of the word being waited on
 973  * @mode: the task state to sleep in
 974  *
 975  * There is a standard hashed waitqueue table for generic use. This
 976  * is the part of the hashtable's accessor API that waits on a bit.
 977  * For instance, if one were to have waiters on a bitflag, one would
 978  * call wait_on_bit() in threads waiting for the bit to clear.
 979  * One uses wait_on_bit() where one is waiting for the bit to clear,
 980  * but has no intention of setting it.
 981  * Returned value will be zero if the bit was cleared, or non-zero
 982  * if the process received a signal and the mode permitted wakeup
 983  * on that signal.
 984  */
 985 static inline int
 986 wait_on_bit(unsigned long *word, int bit, unsigned mode)
 987 {
 988         might_sleep();
 989         if (!test_bit(bit, word))
 990                 return 0;
 991         return out_of_line_wait_on_bit(word, bit,
 992                                        bit_wait,
 993                                        mode);
 994 }
 995
 996 /**
 997  * wait_on_bit_io - wait for a bit to be cleared
 998  * @word: the word being waited on, a kernel virtual address
 999  * @bit: the bit of the word being waited on
1000  * @mode: the task state to sleep in
1001  *
1002  * Use the standard hashed waitqueue table to wait for a bit
1003  * to be cleared.  This is similar to wait_on_bit(), but calls
1004  * io_schedule() instead of schedule() for the actual waiting.
1005  *
1006  * Returned value will be zero if the bit was cleared, or non-zero
1007  * if the process received a signal and the mode permitted wakeup
1008  * on that signal.
1009  */
1010 static inline int
1011 wait_on_bit_io(unsigned long *word, int bit, unsigned mode)
1012 {
1013         might_sleep();
1014         if (!test_bit(bit, word))
1015                 return 0;
1016         return out_of_line_wait_on_bit(word, bit,
1017                                        bit_wait_io,
1018                                        mode);
1019 }
1020
1021 /**
1022  * wait_on_bit_timeout - wait for a bit to be cleared or a timeout elapses
1023  * @word: the word being waited on, a kernel virtual address
1024  * @bit: the bit of the word being waited on
1025  * @mode: the task state to sleep in
1026  * @timeout: timeout, in jiffies
1027  *
1028  * Use the standard hashed waitqueue table to wait for a bit
1029  * to be cleared. This is similar to wait_on_bit(), except also takes a
1030  * timeout parameter.
1031  *
1032  * Returned value will be zero if the bit was cleared before the
1033  * @timeout elapsed, or non-zero if the @timeout elapsed or process
1034  * received a signal and the mode permitted wakeup on that signal.
1035  */
1036 static inline int
1037 wait_on_bit_timeout(unsigned long *word, int bit, unsigned mode,
1038                     unsigned long timeout)
1039 {
1040         might_sleep();
1041         if (!test_bit(bit, word))
1042                 return 0;
1043         return out_of_line_wait_on_bit_timeout(word, bit,
1044                                                bit_wait_timeout,
1045                                                mode, timeout);
1046 }
1047
1048 /**
1049  * wait_on_bit_action - wait for a bit to be cleared
1050  * @word: the word being waited on, a kernel virtual address
1051  * @bit: the bit of the word being waited on
1052  * @action: the function used to sleep, which may take special actions
1053  * @mode: the task state to sleep in
1054  *
1055  * Use the standard hashed waitqueue table to wait for a bit
1056  * to be cleared, and allow the waiting action to be specified.
1057  * This is like wait_on_bit() but allows fine control of how the waiting
1058  * is done.
1059  *
1060  * Returned value will be zero if the bit was cleared, or non-zero
1061  * if the process received a signal and the mode permitted wakeup
1062  * on that signal.
1063  */
1064 static inline int
1065 wait_on_bit_action(unsigned long *word, int bit, wait_bit_action_f *action,
1066                    unsigned mode)
1067 {
1068         might_sleep();
1069         if (!test_bit(bit, word))
1070                 return 0;
1071         return out_of_line_wait_on_bit(word, bit, action, mode);
1072 }
1073
1074 /**
1075  * wait_on_bit_lock - wait for a bit to be cleared, when wanting to set it
1076  * @word: the word being waited on, a kernel virtual address
1077  * @bit: the bit of the word being waited on
1078  * @mode: the task state to sleep in
1079  *
1080  * There is a standard hashed waitqueue table for generic use. This
1081  * is the part of the hashtable's accessor API that waits on a bit
1082  * when one intends to set it, for instance, trying to lock bitflags.
1083  * For instance, if one were to have waiters trying to set bitflag
1084  * and waiting for it to clear before setting it, one would call
1085  * wait_on_bit() in threads waiting to be able to set the bit.
1086  * One uses wait_on_bit_lock() where one is waiting for the bit to
1087  * clear with the intention of setting it, and when done, clearing it.
1088  *
1089  * Returns zero if the bit was (eventually) found to be clear and was
1090  * set.  Returns non-zero if a signal was delivered to the process and
1091  * the @mode allows that signal to wake the process.
1092  */
1093 static inline int
1094 wait_on_bit_lock(unsigned long *word, int bit, unsigned mode)
1095 {
1096         might_sleep();
1097         if (!test_and_set_bit(bit, word))
1098                 return 0;
1099         return out_of_line_wait_on_bit_lock(word, bit, bit_wait, mode);
1100 }
1101
1102 /**
1103  * wait_on_bit_lock_io - wait for a bit to be cleared, when wanting to set it
1104  * @word: the word being waited on, a kernel virtual address
1105  * @bit: the bit of the word being waited on
1106  * @mode: the task state to sleep in
1107  *
1108  * Use the standard hashed waitqueue table to wait for a bit
1109  * to be cleared and then to atomically set it.  This is similar
1110  * to wait_on_bit(), but calls io_schedule() instead of schedule()
1111  * for the actual waiting.
1112  *
1113  * Returns zero if the bit was (eventually) found to be clear and was
1114  * set.  Returns non-zero if a signal was delivered to the process and
1115  * the @mode allows that signal to wake the process.
1116  */
1117 static inline int
1118 wait_on_bit_lock_io(unsigned long *word, int bit, unsigned mode)
1119 {
1120         might_sleep();
1121         if (!test_and_set_bit(bit, word))
1122                 return 0;
1123         return out_of_line_wait_on_bit_lock(word, bit, bit_wait_io, mode);
1124 }
1125
1126 /**
1127  * wait_on_bit_lock_action - wait for a bit to be cleared, when wanting to set it
1128  * @word: the word being waited on, a kernel virtual address
1129  * @bit: the bit of the word being waited on
1130  * @action: the function used to sleep, which may take special actions
1131  * @mode: the task state to sleep in
1132  *
1133  * Use the standard hashed waitqueue table to wait for a bit
1134  * to be cleared and then to set it, and allow the waiting action
1135  * to be specified.
1136  * This is like wait_on_bit() but allows fine control of how the waiting
1137  * is done.
1138  *
1139  * Returns zero if the bit was (eventually) found to be clear and was
1140  * set.  Returns non-zero if a signal was delivered to the process and
1141  * the @mode allows that signal to wake the process.
1142  */
1143 static inline int
1144 wait_on_bit_lock_action(unsigned long *word, int bit, wait_bit_action_f *action,
1145                         unsigned mode)
1146 {
1147         might_sleep();
1148         if (!test_and_set_bit(bit, word))
1149                 return 0;
1150         return out_of_line_wait_on_bit_lock(word, bit, action, mode);
1151 }
1152
1153 /**
1154  * wait_on_atomic_t - Wait for an atomic_t to become 0
1155  * @val: The atomic value being waited on, a kernel virtual address
1156  * @action: the function used to sleep, which may take special actions
1157  * @mode: the task state to sleep in
1158  *
1159  * Wait for an atomic_t to become 0.  We abuse the bit-wait waitqueue table for
1160  * the purpose of getting a waitqueue, but we set the key to a bit number
1161  * outside of the target 'word'.
1162  */
1163 static inline
1164 int wait_on_atomic_t(atomic_t *val, int (*action)(atomic_t *), unsigned mode)
1165 {
1166         might_sleep();
1167         if (atomic_read(val) == 0)
1168                 return 0;
1169         return out_of_line_wait_on_atomic_t(val, action, mode);
1170 }
1171
1172 #endif /* _LINUX_WAIT_H */