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 /**
 106  * waitqueue_active -- locklessly test for waiters on the queue
 107  * @q: the waitqueue to test for waiters
 108  *
 109  * returns true if the wait list is not empty
 110  *
 111  * NOTE: this function is lockless and requires care, incorrect usage _will_
 112  * lead to sporadic and non-obvious failure.
 113  *
 114  * Use either while holding wait_queue_head_t::lock or when used for wakeups
 115  * with an extra smp_mb() like:
 116  *
 117  *      CPU0 - waker                    CPU1 - waiter
 118  *
 119  *                                      for (;;) {
 120  *      @cond = true;                     prepare_to_wait(&wq, &wait, state);
 121  *      smp_mb();                         // smp_mb() from set_current_state()
 122  *      if (waitqueue_active(wq))         if (@cond)
 123  *        wake_up(wq);                      break;
 124  *                                        schedule();
 125  *                                      }
 126  *                                      finish_wait(&wq, &wait);
 127  *
 128  * Because without the explicit smp_mb() it's possible for the
 129  * waitqueue_active() load to get hoisted over the @cond store such that we'll
 130  * observe an empty wait list while the waiter might not observe @cond.
 131  *
 132  * Also note that this 'optimization' trades a spin_lock() for an smp_mb(),
 133  * which (when the lock is uncontended) are of roughly equal cost.
 134  */
 135 static inline int waitqueue_active(wait_queue_head_t *q)
 136 {
 137         return !list_empty(&q->task_list);
 138 }
 139
 140 /**
 141  * wq_has_sleeper - check if there are any waiting processes
 142  * @wq: wait queue head
 143  *
 144  * Returns true if wq has waiting processes
 145  *
 146  * Please refer to the comment for waitqueue_active.
 147  */
 148 static inline bool wq_has_sleeper(wait_queue_head_t *wq)
 149 {
 150         /*
 151          * We need to be sure we are in sync with the
 152          * add_wait_queue modifications to the wait queue.
 153          *
 154          * This memory barrier should be paired with one on the
 155          * waiting side.
 156          */
 157         smp_mb();
 158         return waitqueue_active(wq);
 159 }
 160
 161 extern void add_wait_queue(wait_queue_head_t *q, wait_queue_t *wait);
 162 extern void add_wait_queue_exclusive(wait_queue_head_t *q, wait_queue_t *wait);
 163 extern void remove_wait_queue(wait_queue_head_t *q, wait_queue_t *wait);
 164
 165 static inline void __add_wait_queue(wait_queue_head_t *head, wait_queue_t *new)
 166 {
 167         list_add(&new->task_list, &head->task_list);
 168 }
 169
 170 /*
 171  * Used for wake-one threads:
 172  */
 173 static inline void
 174 __add_wait_queue_exclusive(wait_queue_head_t *q, wait_queue_t *wait)
 175 {
 176         wait->flags |= WQ_FLAG_EXCLUSIVE;
 177         __add_wait_queue(q, wait);
 178 }
 179
 180 static inline void __add_wait_queue_tail(wait_queue_head_t *head,
 181                                          wait_queue_t *new)
 182 {
 183         list_add_tail(&new->task_list, &head->task_list);
 184 }
 185
 186 static inline void
 187 __add_wait_queue_tail_exclusive(wait_queue_head_t *q, wait_queue_t *wait)
 188 {
 189         wait->flags |= WQ_FLAG_EXCLUSIVE;
 190         __add_wait_queue_tail(q, wait);
 191 }
 192
 193 static inline void
 194 __remove_wait_queue(wait_queue_head_t *head, wait_queue_t *old)
 195 {
 196         list_del(&old->task_list);
 197 }
 198
 199 typedef int wait_bit_action_f(struct wait_bit_key *, int mode);
 200 void __wake_up(wait_queue_head_t *q, unsigned int mode, int nr, void *key);
 201 void __wake_up_locked_key(wait_queue_head_t *q, unsigned int mode, void *key);
 202 void __wake_up_sync_key(wait_queue_head_t *q, unsigned int mode, int nr, void *key);
 203 void __wake_up_locked(wait_queue_head_t *q, unsigned int mode, int nr);
 204 void __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr);
 205 void __wake_up_pollfree(wait_queue_head_t *wq_head);
 206 void __wake_up_bit(wait_queue_head_t *, void *, int);
 207 int __wait_on_bit(wait_queue_head_t *, struct wait_bit_queue *, wait_bit_action_f *, unsigned);
 208 int __wait_on_bit_lock(wait_queue_head_t *, struct wait_bit_queue *, wait_bit_action_f *, unsigned);
 209 void wake_up_bit(void *, int);
 210 void wake_up_atomic_t(atomic_t *);
 211 int out_of_line_wait_on_bit(void *, int, wait_bit_action_f *, unsigned);
 212 int out_of_line_wait_on_bit_timeout(void *, int, wait_bit_action_f *, unsigned, unsigned long);
 213 int out_of_line_wait_on_bit_lock(void *, int, wait_bit_action_f *, unsigned);
 214 int out_of_line_wait_on_atomic_t(atomic_t *, int (*)(atomic_t *), unsigned);
 215 wait_queue_head_t *bit_waitqueue(void *, int);
 216
 217 #define wake_up(x)                      __wake_up(x, TASK_NORMAL, 1, NULL)
 218 #define wake_up_nr(x, nr)               __wake_up(x, TASK_NORMAL, nr, NULL)
 219 #define wake_up_all(x)                  __wake_up(x, TASK_NORMAL, 0, NULL)
 220 #define wake_up_locked(x)               __wake_up_locked((x), TASK_NORMAL, 1)
 221 #define wake_up_all_locked(x)           __wake_up_locked((x), TASK_NORMAL, 0)
 222
 223 #define wake_up_interruptible(x)        __wake_up(x, TASK_INTERRUPTIBLE, 1, NULL)
 224 #define wake_up_interruptible_nr(x, nr) __wake_up(x, TASK_INTERRUPTIBLE, nr, NULL)
 225 #define wake_up_interruptible_all(x)    __wake_up(x, TASK_INTERRUPTIBLE, 0, NULL)
 226 #define wake_up_interruptible_sync(x)   __wake_up_sync((x), TASK_INTERRUPTIBLE, 1)
 227
 228 /*
 229  * Wakeup macros to be used to report events to the targets.
 230  */
 231 #define wake_up_poll(x, m)                                              \
 232         __wake_up(x, TASK_NORMAL, 1, (void *) (m))
 233 #define wake_up_locked_poll(x, m)                                       \
 234         __wake_up_locked_key((x), TASK_NORMAL, (void *) (m))
 235 #define wake_up_interruptible_poll(x, m)                                \
 236         __wake_up(x, TASK_INTERRUPTIBLE, 1, (void *) (m))
 237 #define wake_up_interruptible_sync_poll(x, m)                           \
 238         __wake_up_sync_key((x), TASK_INTERRUPTIBLE, 1, (void *) (m))
 239
 240 /**
 241  * wake_up_pollfree - signal that a polled waitqueue is going away
 242  * @wq_head: the wait queue head
 243  *
 244  * In the very rare cases where a ->poll() implementation uses a waitqueue whose
 245  * lifetime is tied to a task rather than to the 'struct file' being polled,
 246  * this function must be called before the waitqueue is freed so that
 247  * non-blocking polls (e.g. epoll) are notified that the queue is going away.
 248  *
 249  * The caller must also RCU-delay the freeing of the wait_queue_head, e.g. via
 250  * an explicit synchronize_rcu() or call_rcu(), or via SLAB_DESTROY_BY_RCU.
 251  */
 252 static inline void wake_up_pollfree(wait_queue_head_t *wq_head)
 253 {
 254         /*
 255          * For performance reasons, we don't always take the queue lock here.
 256          * Therefore, we might race with someone removing the last entry from
 257          * the queue, and proceed while they still hold the queue lock.
 258          * However, rcu_read_lock() is required to be held in such cases, so we
 259          * can safely proceed with an RCU-delayed free.
 260          */
 261         if (waitqueue_active(wq_head))
 262                 __wake_up_pollfree(wq_head);
 263 }
 264
 265 #define ___wait_cond_timeout(condition)                                 \
 266 ({                                                                      \
 267         bool __cond = (condition);                                      \
 268         if (__cond && !__ret)                                           \
 269                 __ret = 1;                                              \
 270         __cond || !__ret;                                               \
 271 })
 272
 273 #define ___wait_is_interruptible(state)                                 \
 274         (!__builtin_constant_p(state) ||                                \
 275                 state == TASK_INTERRUPTIBLE || state == TASK_KILLABLE)  \
 276
 277 extern void init_wait_entry(wait_queue_t *__wait, int flags);
 278
 279 /*
 280  * The below macro ___wait_event() has an explicit shadow of the __ret
 281  * variable when used from the wait_event_*() macros.
 282  *
 283  * This is so that both can use the ___wait_cond_timeout() construct
 284  * to wrap the condition.
 285  *
 286  * The type inconsistency of the wait_event_*() __ret variable is also
 287  * on purpose; we use long where we can return timeout values and int
 288  * otherwise.
 289  */
 290
 291 #define ___wait_event(wq, condition, state, exclusive, ret, cmd)        \
 292 ({                                                                      \
 293         __label__ __out;                                                \
 294         wait_queue_t __wait;                                            \
 295         long __ret = ret;       /* explicit shadow */                   \
 296                                                                         \
 297         init_wait_entry(&__wait, exclusive ? WQ_FLAG_EXCLUSIVE : 0);    \
 298         for (;;) {                                                      \
 299                 long __int = prepare_to_wait_event(&wq, &__wait, state);\
 300                                                                         \
 301                 if (condition)                                          \
 302                         break;                                          \
 303                                                                         \
 304                 if (___wait_is_interruptible(state) && __int) {         \
 305                         __ret = __int;                                  \
 306                         goto __out;                                     \
 307                 }                                                       \
 308                                                                         \
 309                 cmd;                                                    \
 310         }                                                               \
 311         finish_wait(&wq, &__wait);                                      \
 312 __out:  __ret;                                                          \
 313 })
 314
 315 #define __wait_event(wq, condition)                                     \
 316         (void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0, 0,  \
 317                             schedule())
 318
 319 /**
 320  * wait_event - sleep until a condition gets true
 321  * @wq: the waitqueue to wait on
 322  * @condition: a C expression for the event to wait for
 323  *
 324  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 325  * @condition evaluates to true. The @condition is checked each time
 326  * the waitqueue @wq is woken up.
 327  *
 328  * wake_up() has to be called after changing any variable that could
 329  * change the result of the wait condition.
 330  */
 331 #define wait_event(wq, condition)                                       \
 332 do {                                                                    \
 333         might_sleep();                                                  \
 334         if (condition)                                                  \
 335                 break;                                                  \
 336         __wait_event(wq, condition);                                    \
 337 } while (0)
 338
 339 #define __io_wait_event(wq, condition)                                  \
 340         (void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0, 0,  \
 341                             io_schedule())
 342
 343 /*
 344  * io_wait_event() -- like wait_event() but with io_schedule()
 345  */
 346 #define io_wait_event(wq, condition)                                    \
 347 do {                                                                    \
 348         might_sleep();                                                  \
 349         if (condition)                                                  \
 350                 break;                                                  \
 351         __io_wait_event(wq, condition);                                 \
 352 } while (0)
 353
 354 #define __wait_event_freezable(wq, condition)                           \
 355         ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 0, 0,          \
 356                             schedule(); try_to_freeze())
 357
 358 /**
 359  * wait_event_freezable - sleep (or freeze) until a condition gets true
 360  * @wq: the waitqueue to wait on
 361  * @condition: a C expression for the event to wait for
 362  *
 363  * The process is put to sleep (TASK_INTERRUPTIBLE -- so as not to contribute
 364  * to system load) until the @condition evaluates to true. The
 365  * @condition is checked each time the waitqueue @wq is woken up.
 366  *
 367  * wake_up() has to be called after changing any variable that could
 368  * change the result of the wait condition.
 369  */
 370 #define wait_event_freezable(wq, condition)                             \
 371 ({                                                                      \
 372         int __ret = 0;                                                  \
 373         might_sleep();                                                  \
 374         if (!(condition))                                               \
 375                 __ret = __wait_event_freezable(wq, condition);          \
 376         __ret;                                                          \
 377 })
 378
 379 #define __wait_event_timeout(wq, condition, timeout)                    \
 380         ___wait_event(wq, ___wait_cond_timeout(condition),              \
 381                       TASK_UNINTERRUPTIBLE, 0, timeout,                 \
 382                       __ret = schedule_timeout(__ret))
 383
 384 /**
 385  * wait_event_timeout - sleep until a condition gets true or a timeout elapses
 386  * @wq: the waitqueue to wait on
 387  * @condition: a C expression for the event to wait for
 388  * @timeout: timeout, in jiffies
 389  *
 390  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 391  * @condition evaluates to true. The @condition is checked each time
 392  * the waitqueue @wq is woken up.
 393  *
 394  * wake_up() has to be called after changing any variable that could
 395  * change the result of the wait condition.
 396  *
 397  * Returns:
 398  * 0 if the @condition evaluated to %false after the @timeout elapsed,
 399  * 1 if the @condition evaluated to %true after the @timeout elapsed,
 400  * or the remaining jiffies (at least 1) if the @condition evaluated
 401  * to %true before the @timeout elapsed.
 402  */
 403 #define wait_event_timeout(wq, condition, timeout)                      \
 404 ({                                                                      \
 405         long __ret = timeout;                                           \
 406         might_sleep();                                                  \
 407         if (!___wait_cond_timeout(condition))                           \
 408                 __ret = __wait_event_timeout(wq, condition, timeout);   \
 409         __ret;                                                          \
 410 })
 411
 412 #define __wait_event_freezable_timeout(wq, condition, timeout)          \
 413         ___wait_event(wq, ___wait_cond_timeout(condition),              \
 414                       TASK_INTERRUPTIBLE, 0, timeout,                   \
 415                       __ret = schedule_timeout(__ret); try_to_freeze())
 416
 417 /*
 418  * like wait_event_timeout() -- except it uses TASK_INTERRUPTIBLE to avoid
 419  * increasing load and is freezable.
 420  */
 421 #define wait_event_freezable_timeout(wq, condition, timeout)            \
 422 ({                                                                      \
 423         long __ret = timeout;                                           \
 424         might_sleep();                                                  \
 425         if (!___wait_cond_timeout(condition))                           \
 426                 __ret = __wait_event_freezable_timeout(wq, condition, timeout); \
 427         __ret;                                                          \
 428 })
 429
 430 #define __wait_event_exclusive_cmd(wq, condition, cmd1, cmd2)           \
 431         (void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 1, 0,  \
 432                             cmd1; schedule(); cmd2)
 433 /*
 434  * Just like wait_event_cmd(), except it sets exclusive flag
 435  */
 436 #define wait_event_exclusive_cmd(wq, condition, cmd1, cmd2)             \
 437 do {                                                                    \
 438         if (condition)                                                  \
 439                 break;                                                  \
 440         __wait_event_exclusive_cmd(wq, condition, cmd1, cmd2);          \
 441 } while (0)
 442
 443 #define __wait_event_cmd(wq, condition, cmd1, cmd2)                     \
 444         (void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0, 0,  \
 445                             cmd1; schedule(); cmd2)
 446
 447 /**
 448  * wait_event_cmd - sleep until a condition gets true
 449  * @wq: the waitqueue to wait on
 450  * @condition: a C expression for the event to wait for
 451  * @cmd1: the command will be executed before sleep
 452  * @cmd2: the command will be executed after sleep
 453  *
 454  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 455  * @condition evaluates to true. The @condition is checked each time
 456  * the waitqueue @wq is woken up.
 457  *
 458  * wake_up() has to be called after changing any variable that could
 459  * change the result of the wait condition.
 460  */
 461 #define wait_event_cmd(wq, condition, cmd1, cmd2)                       \
 462 do {                                                                    \
 463         if (condition)                                                  \
 464                 break;                                                  \
 465         __wait_event_cmd(wq, condition, cmd1, cmd2);                    \
 466 } while (0)
 467
 468 #define __wait_event_interruptible(wq, condition)                       \
 469         ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 0, 0,          \
 470                       schedule())
 471
 472 /**
 473  * wait_event_interruptible - sleep until a condition gets true
 474  * @wq: the waitqueue to wait on
 475  * @condition: a C expression for the event to wait for
 476  *
 477  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 478  * @condition evaluates to true or a signal is received.
 479  * The @condition is checked each time the waitqueue @wq is woken up.
 480  *
 481  * wake_up() has to be called after changing any variable that could
 482  * change the result of the wait condition.
 483  *
 484  * The function will return -ERESTARTSYS if it was interrupted by a
 485  * signal and 0 if @condition evaluated to true.
 486  */
 487 #define wait_event_interruptible(wq, condition)                         \
 488 ({                                                                      \
 489         int __ret = 0;                                                  \
 490         might_sleep();                                                  \
 491         if (!(condition))                                               \
 492                 __ret = __wait_event_interruptible(wq, condition);      \
 493         __ret;                                                          \
 494 })
 495
 496 #define __wait_event_interruptible_timeout(wq, condition, timeout)      \
 497         ___wait_event(wq, ___wait_cond_timeout(condition),              \
 498                       TASK_INTERRUPTIBLE, 0, timeout,                   \
 499                       __ret = schedule_timeout(__ret))
 500
 501 /**
 502  * wait_event_interruptible_timeout - sleep until a condition gets true or a timeout elapses
 503  * @wq: the waitqueue to wait on
 504  * @condition: a C expression for the event to wait for
 505  * @timeout: timeout, in jiffies
 506  *
 507  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 508  * @condition evaluates to true or a signal is received.
 509  * The @condition is checked each time the waitqueue @wq is woken up.
 510  *
 511  * wake_up() has to be called after changing any variable that could
 512  * change the result of the wait condition.
 513  *
 514  * Returns:
 515  * 0 if the @condition evaluated to %false after the @timeout elapsed,
 516  * 1 if the @condition evaluated to %true after the @timeout elapsed,
 517  * the remaining jiffies (at least 1) if the @condition evaluated
 518  * to %true before the @timeout elapsed, or -%ERESTARTSYS if it was
 519  * interrupted by a signal.
 520  */
 521 #define wait_event_interruptible_timeout(wq, condition, timeout)        \
 522 ({                                                                      \
 523         long __ret = timeout;                                           \
 524         might_sleep();                                                  \
 525         if (!___wait_cond_timeout(condition))                           \
 526                 __ret = __wait_event_interruptible_timeout(wq,          \
 527                                                 condition, timeout);    \
 528         __ret;                                                          \
 529 })
 530
 531 #define __wait_event_hrtimeout(wq, condition, timeout, state)           \
 532 ({                                                                      \
 533         int __ret = 0;                                                  \
 534         struct hrtimer_sleeper __t;                                     \
 535                                                                         \
 536         hrtimer_init_on_stack(&__t.timer, CLOCK_MONOTONIC,              \
 537                               HRTIMER_MODE_REL);                        \
 538         hrtimer_init_sleeper(&__t, current);                            \
 539         if ((timeout).tv64 != KTIME_MAX)                                \
 540                 hrtimer_start_range_ns(&__t.timer, timeout,             \
 541                                        current->timer_slack_ns,         \
 542                                        HRTIMER_MODE_REL);               \
 543                                                                         \
 544         __ret = ___wait_event(wq, condition, state, 0, 0,               \
 545                 if (!__t.task) {                                        \
 546                         __ret = -ETIME;                                 \
 547                         break;                                          \
 548                 }                                                       \
 549                 schedule());                                            \
 550                                                                         \
 551         hrtimer_cancel(&__t.timer);                                     \
 552         destroy_hrtimer_on_stack(&__t.timer);                           \
 553         __ret;                                                          \
 554 })
 555
 556 /**
 557  * wait_event_hrtimeout - sleep until a condition gets true or a timeout elapses
 558  * @wq: the waitqueue to wait on
 559  * @condition: a C expression for the event to wait for
 560  * @timeout: timeout, as a ktime_t
 561  *
 562  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 563  * @condition evaluates to true or a signal is received.
 564  * The @condition is checked each time the waitqueue @wq is woken up.
 565  *
 566  * wake_up() has to be called after changing any variable that could
 567  * change the result of the wait condition.
 568  *
 569  * The function returns 0 if @condition became true, or -ETIME if the timeout
 570  * elapsed.
 571  */
 572 #define wait_event_hrtimeout(wq, condition, timeout)                    \
 573 ({                                                                      \
 574         int __ret = 0;                                                  \
 575         might_sleep();                                                  \
 576         if (!(condition))                                               \
 577                 __ret = __wait_event_hrtimeout(wq, condition, timeout,  \
 578                                                TASK_UNINTERRUPTIBLE);   \
 579         __ret;                                                          \
 580 })
 581
 582 /**
 583  * wait_event_interruptible_hrtimeout - sleep until a condition gets true or a timeout elapses
 584  * @wq: the waitqueue to wait on
 585  * @condition: a C expression for the event to wait for
 586  * @timeout: timeout, as a ktime_t
 587  *
 588  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 589  * @condition evaluates to true or a signal is received.
 590  * The @condition is checked each time the waitqueue @wq is woken up.
 591  *
 592  * wake_up() has to be called after changing any variable that could
 593  * change the result of the wait condition.
 594  *
 595  * The function returns 0 if @condition became true, -ERESTARTSYS if it was
 596  * interrupted by a signal, or -ETIME if the timeout elapsed.
 597  */
 598 #define wait_event_interruptible_hrtimeout(wq, condition, timeout)      \
 599 ({                                                                      \
 600         long __ret = 0;                                                 \
 601         might_sleep();                                                  \
 602         if (!(condition))                                               \
 603                 __ret = __wait_event_hrtimeout(wq, condition, timeout,  \
 604                                                TASK_INTERRUPTIBLE);     \
 605         __ret;                                                          \
 606 })
 607
 608 #define __wait_event_interruptible_exclusive(wq, condition)             \
 609         ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 1, 0,          \
 610                       schedule())
 611
 612 #define wait_event_interruptible_exclusive(wq, condition)               \
 613 ({                                                                      \
 614         int __ret = 0;                                                  \
 615         might_sleep();                                                  \
 616         if (!(condition))                                               \
 617                 __ret = __wait_event_interruptible_exclusive(wq, condition);\
 618         __ret;                                                          \
 619 })
 620
 621 #define __wait_event_killable_exclusive(wq, condition)                  \
 622         ___wait_event(wq, condition, TASK_KILLABLE, 1, 0,               \
 623                       schedule())
 624
 625 #define wait_event_killable_exclusive(wq, condition)                    \
 626 ({                                                                      \
 627         int __ret = 0;                                                  \
 628         might_sleep();                                                  \
 629         if (!(condition))                                               \
 630                 __ret = __wait_event_killable_exclusive(wq, condition); \
 631         __ret;                                                          \
 632 })
 633
 634
 635 #define __wait_event_freezable_exclusive(wq, condition)                 \
 636         ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 1, 0,          \
 637                         schedule(); try_to_freeze())
 638
 639 #define wait_event_freezable_exclusive(wq, condition)                   \
 640 ({                                                                      \
 641         int __ret = 0;                                                  \
 642         might_sleep();                                                  \
 643         if (!(condition))                                               \
 644                 __ret = __wait_event_freezable_exclusive(wq, condition);\
 645         __ret;                                                          \
 646 })
 647
 648
 649 #define __wait_event_interruptible_locked(wq, condition, exclusive, irq) \
 650 ({                                                                      \
 651         int __ret = 0;                                                  \
 652         DEFINE_WAIT(__wait);                                            \
 653         if (exclusive)                                                  \
 654                 __wait.flags |= WQ_FLAG_EXCLUSIVE;                      \
 655         do {                                                            \
 656                 if (likely(list_empty(&__wait.task_list)))              \
 657                         __add_wait_queue_tail(&(wq), &__wait);          \
 658                 set_current_state(TASK_INTERRUPTIBLE);                  \
 659                 if (signal_pending(current)) {                          \
 660                         __ret = -ERESTARTSYS;                           \
 661                         break;                                          \
 662                 }                                                       \
 663                 if (irq)                                                \
 664                         spin_unlock_irq(&(wq).lock);                    \
 665                 else                                                    \
 666                         spin_unlock(&(wq).lock);                        \
 667                 schedule();                                             \
 668                 if (irq)                                                \
 669                         spin_lock_irq(&(wq).lock);                      \
 670                 else                                                    \
 671                         spin_lock(&(wq).lock);                          \
 672         } while (!(condition));                                         \
 673         __remove_wait_queue(&(wq), &__wait);                            \
 674         __set_current_state(TASK_RUNNING);                              \
 675         __ret;                                                          \
 676 })
 677
 678
 679 /**
 680  * wait_event_interruptible_locked - sleep until a condition gets true
 681  * @wq: the waitqueue to wait on
 682  * @condition: a C expression for the event to wait for
 683  *
 684  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 685  * @condition evaluates to true or a signal is received.
 686  * The @condition is checked each time the waitqueue @wq is woken up.
 687  *
 688  * It must be called with wq.lock being held.  This spinlock is
 689  * unlocked while sleeping but @condition testing is done while lock
 690  * is held and when this macro exits the lock is held.
 691  *
 692  * The lock is locked/unlocked using spin_lock()/spin_unlock()
 693  * functions which must match the way they are locked/unlocked outside
 694  * of this macro.
 695  *
 696  * wake_up_locked() has to be called after changing any variable that could
 697  * change the result of the wait condition.
 698  *
 699  * The function will return -ERESTARTSYS if it was interrupted by a
 700  * signal and 0 if @condition evaluated to true.
 701  */
 702 #define wait_event_interruptible_locked(wq, condition)                  \
 703         ((condition)                                                    \
 704          ? 0 : __wait_event_interruptible_locked(wq, condition, 0, 0))
 705
 706 /**
 707  * wait_event_interruptible_locked_irq - sleep until a condition gets true
 708  * @wq: the waitqueue to wait on
 709  * @condition: a C expression for the event to wait for
 710  *
 711  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 712  * @condition evaluates to true or a signal is received.
 713  * The @condition is checked each time the waitqueue @wq is woken up.
 714  *
 715  * It must be called with wq.lock being held.  This spinlock is
 716  * unlocked while sleeping but @condition testing is done while lock
 717  * is held and when this macro exits the lock is held.
 718  *
 719  * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq()
 720  * functions which must match the way they are locked/unlocked outside
 721  * of this macro.
 722  *
 723  * wake_up_locked() has to be called after changing any variable that could
 724  * change the result of the wait condition.
 725  *
 726  * The function will return -ERESTARTSYS if it was interrupted by a
 727  * signal and 0 if @condition evaluated to true.
 728  */
 729 #define wait_event_interruptible_locked_irq(wq, condition)              \
 730         ((condition)                                                    \
 731          ? 0 : __wait_event_interruptible_locked(wq, condition, 0, 1))
 732
 733 /**
 734  * wait_event_interruptible_exclusive_locked - sleep exclusively until a condition gets true
 735  * @wq: the waitqueue to wait on
 736  * @condition: a C expression for the event to wait for
 737  *
 738  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 739  * @condition evaluates to true or a signal is received.
 740  * The @condition is checked each time the waitqueue @wq is woken up.
 741  *
 742  * It must be called with wq.lock being held.  This spinlock is
 743  * unlocked while sleeping but @condition testing is done while lock
 744  * is held and when this macro exits the lock is held.
 745  *
 746  * The lock is locked/unlocked using spin_lock()/spin_unlock()
 747  * functions which must match the way they are locked/unlocked outside
 748  * of this macro.
 749  *
 750  * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
 751  * set thus when other process waits process on the list if this
 752  * process is awaken further processes are not considered.
 753  *
 754  * wake_up_locked() has to be called after changing any variable that could
 755  * change the result of the wait condition.
 756  *
 757  * The function will return -ERESTARTSYS if it was interrupted by a
 758  * signal and 0 if @condition evaluated to true.
 759  */
 760 #define wait_event_interruptible_exclusive_locked(wq, condition)        \
 761         ((condition)                                                    \
 762          ? 0 : __wait_event_interruptible_locked(wq, condition, 1, 0))
 763
 764 /**
 765  * wait_event_interruptible_exclusive_locked_irq - sleep until a condition gets true
 766  * @wq: the waitqueue to wait on
 767  * @condition: a C expression for the event to wait for
 768  *
 769  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 770  * @condition evaluates to true or a signal is received.
 771  * The @condition is checked each time the waitqueue @wq is woken up.
 772  *
 773  * It must be called with wq.lock being held.  This spinlock is
 774  * unlocked while sleeping but @condition testing is done while lock
 775  * is held and when this macro exits the lock is held.
 776  *
 777  * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq()
 778  * functions which must match the way they are locked/unlocked outside
 779  * of this macro.
 780  *
 781  * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
 782  * set thus when other process waits process on the list if this
 783  * process is awaken further processes are not considered.
 784  *
 785  * wake_up_locked() has to be called after changing any variable that could
 786  * change the result of the wait condition.
 787  *
 788  * The function will return -ERESTARTSYS if it was interrupted by a
 789  * signal and 0 if @condition evaluated to true.
 790  */
 791 #define wait_event_interruptible_exclusive_locked_irq(wq, condition)    \
 792         ((condition)                                                    \
 793          ? 0 : __wait_event_interruptible_locked(wq, condition, 1, 1))
 794
 795
 796 #define __wait_event_killable(wq, condition)                            \
 797         ___wait_event(wq, condition, TASK_KILLABLE, 0, 0, schedule())
 798
 799 /**
 800  * wait_event_killable - sleep until a condition gets true
 801  * @wq: the waitqueue to wait on
 802  * @condition: a C expression for the event to wait for
 803  *
 804  * The process is put to sleep (TASK_KILLABLE) until the
 805  * @condition evaluates to true or a signal is received.
 806  * The @condition is checked each time the waitqueue @wq is woken up.
 807  *
 808  * wake_up() has to be called after changing any variable that could
 809  * change the result of the wait condition.
 810  *
 811  * The function will return -ERESTARTSYS if it was interrupted by a
 812  * signal and 0 if @condition evaluated to true.
 813  */
 814 #define wait_event_killable(wq, condition)                              \
 815 ({                                                                      \
 816         int __ret = 0;                                                  \
 817         might_sleep();                                                  \
 818         if (!(condition))                                               \
 819                 __ret = __wait_event_killable(wq, condition);           \
 820         __ret;                                                          \
 821 })
 822
 823
 824 #define __wait_event_lock_irq(wq, condition, lock, cmd)                 \
 825         (void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0, 0,  \
 826                             spin_unlock_irq(&lock);                     \
 827                             cmd;                                        \
 828                             schedule();                                 \
 829                             spin_lock_irq(&lock))
 830
 831 /**
 832  * wait_event_lock_irq_cmd - sleep until a condition gets true. The
 833  *                           condition is checked under the lock. This
 834  *                           is expected to be called with the lock
 835  *                           taken.
 836  * @wq: the waitqueue to wait on
 837  * @condition: a C expression for the event to wait for
 838  * @lock: a locked spinlock_t, which will be released before cmd
 839  *        and schedule() and reacquired afterwards.
 840  * @cmd: a command which is invoked outside the critical section before
 841  *       sleep
 842  *
 843  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 844  * @condition evaluates to true. The @condition is checked each time
 845  * the waitqueue @wq is woken up.
 846  *
 847  * wake_up() has to be called after changing any variable that could
 848  * change the result of the wait condition.
 849  *
 850  * This is supposed to be called while holding the lock. The lock is
 851  * dropped before invoking the cmd and going to sleep and is reacquired
 852  * afterwards.
 853  */
 854 #define wait_event_lock_irq_cmd(wq, condition, lock, cmd)               \
 855 do {                                                                    \
 856         if (condition)                                                  \
 857                 break;                                                  \
 858         __wait_event_lock_irq(wq, condition, lock, cmd);                \
 859 } while (0)
 860
 861 /**
 862  * wait_event_lock_irq - sleep until a condition gets true. The
 863  *                       condition is checked under the lock. This
 864  *                       is expected to be called with the lock
 865  *                       taken.
 866  * @wq: the waitqueue to wait on
 867  * @condition: a C expression for the event to wait for
 868  * @lock: a locked spinlock_t, which will be released before schedule()
 869  *        and reacquired afterwards.
 870  *
 871  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 872  * @condition evaluates to true. The @condition is checked each time
 873  * the waitqueue @wq is woken up.
 874  *
 875  * wake_up() has to be called after changing any variable that could
 876  * change the result of the wait condition.
 877  *
 878  * This is supposed to be called while holding the lock. The lock is
 879  * dropped before going to sleep and is reacquired afterwards.
 880  */
 881 #define wait_event_lock_irq(wq, condition, lock)                        \
 882 do {                                                                    \
 883         if (condition)                                                  \
 884                 break;                                                  \
 885         __wait_event_lock_irq(wq, condition, lock, );                   \
 886 } while (0)
 887
 888
 889 #define __wait_event_interruptible_lock_irq(wq, condition, lock, cmd)   \
 890         ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 0, 0,          \
 891                       spin_unlock_irq(&lock);                           \
 892                       cmd;                                              \
 893                       schedule();                                       \
 894                       spin_lock_irq(&lock))
 895
 896 /**
 897  * wait_event_interruptible_lock_irq_cmd - sleep until a condition gets true.
 898  *              The condition is checked under the lock. This is expected to
 899  *              be called with the lock taken.
 900  * @wq: the waitqueue to wait on
 901  * @condition: a C expression for the event to wait for
 902  * @lock: a locked spinlock_t, which will be released before cmd and
 903  *        schedule() and reacquired afterwards.
 904  * @cmd: a command which is invoked outside the critical section before
 905  *       sleep
 906  *
 907  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 908  * @condition evaluates to true or a signal is received. The @condition is
 909  * checked each time the waitqueue @wq is woken up.
 910  *
 911  * wake_up() has to be called after changing any variable that could
 912  * change the result of the wait condition.
 913  *
 914  * This is supposed to be called while holding the lock. The lock is
 915  * dropped before invoking the cmd and going to sleep and is reacquired
 916  * afterwards.
 917  *
 918  * The macro will return -ERESTARTSYS if it was interrupted by a signal
 919  * and 0 if @condition evaluated to true.
 920  */
 921 #define wait_event_interruptible_lock_irq_cmd(wq, condition, lock, cmd) \
 922 ({                                                                      \
 923         int __ret = 0;                                                  \
 924         if (!(condition))                                               \
 925                 __ret = __wait_event_interruptible_lock_irq(wq,         \
 926                                                 condition, lock, cmd);  \
 927         __ret;                                                          \
 928 })
 929
 930 /**
 931  * wait_event_interruptible_lock_irq - sleep until a condition gets true.
 932  *              The condition is checked under the lock. This is expected
 933  *              to be called with the lock taken.
 934  * @wq: the waitqueue to wait on
 935  * @condition: a C expression for the event to wait for
 936  * @lock: a locked spinlock_t, which will be released before schedule()
 937  *        and reacquired afterwards.
 938  *
 939  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 940  * @condition evaluates to true or signal is received. The @condition is
 941  * checked each time the waitqueue @wq is woken up.
 942  *
 943  * wake_up() has to be called after changing any variable that could
 944  * change the result of the wait condition.
 945  *
 946  * This is supposed to be called while holding the lock. The lock is
 947  * dropped before going to sleep and is reacquired afterwards.
 948  *
 949  * The macro will return -ERESTARTSYS if it was interrupted by a signal
 950  * and 0 if @condition evaluated to true.
 951  */
 952 #define wait_event_interruptible_lock_irq(wq, condition, lock)          \
 953 ({                                                                      \
 954         int __ret = 0;                                                  \
 955         if (!(condition))                                               \
 956                 __ret = __wait_event_interruptible_lock_irq(wq,         \
 957                                                 condition, lock,);      \
 958         __ret;                                                          \
 959 })
 960
 961 #define __wait_event_interruptible_lock_irq_timeout(wq, condition,      \
 962                                                     lock, timeout)      \
 963         ___wait_event(wq, ___wait_cond_timeout(condition),              \
 964                       TASK_INTERRUPTIBLE, 0, timeout,                   \
 965                       spin_unlock_irq(&lock);                           \
 966                       __ret = schedule_timeout(__ret);                  \
 967                       spin_lock_irq(&lock));
 968
 969 /**
 970  * wait_event_interruptible_lock_irq_timeout - sleep until a condition gets
 971  *              true or a timeout elapses. The condition is checked under
 972  *              the lock. This is expected to be called with the lock taken.
 973  * @wq: the waitqueue to wait on
 974  * @condition: a C expression for the event to wait for
 975  * @lock: a locked spinlock_t, which will be released before schedule()
 976  *        and reacquired afterwards.
 977  * @timeout: timeout, in jiffies
 978  *
 979  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 980  * @condition evaluates to true or signal is received. The @condition is
 981  * checked each time the waitqueue @wq is woken up.
 982  *
 983  * wake_up() has to be called after changing any variable that could
 984  * change the result of the wait condition.
 985  *
 986  * This is supposed to be called while holding the lock. The lock is
 987  * dropped before going to sleep and is reacquired afterwards.
 988  *
 989  * The function returns 0 if the @timeout elapsed, -ERESTARTSYS if it
 990  * was interrupted by a signal, and the remaining jiffies otherwise
 991  * if the condition evaluated to true before the timeout elapsed.
 992  */
 993 #define wait_event_interruptible_lock_irq_timeout(wq, condition, lock,  \
 994                                                   timeout)              \
 995 ({                                                                      \
 996         long __ret = timeout;                                           \
 997         if (!___wait_cond_timeout(condition))                           \
 998                 __ret = __wait_event_interruptible_lock_irq_timeout(    \
 999                                         wq, condition, lock, timeout);  \
1000         __ret;                                                          \
1001 })
1002
1003 /*
1004  * Waitqueues which are removed from the waitqueue_head at wakeup time
1005  */
1006 void prepare_to_wait(wait_queue_head_t *q, wait_queue_t *wait, int state);
1007 void prepare_to_wait_exclusive(wait_queue_head_t *q, wait_queue_t *wait, int state);
1008 long prepare_to_wait_event(wait_queue_head_t *q, wait_queue_t *wait, int state);
1009 void finish_wait(wait_queue_head_t *q, wait_queue_t *wait);
1010 long wait_woken(wait_queue_t *wait, unsigned mode, long timeout);
1011 int woken_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
1012 int autoremove_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
1013 int wake_bit_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
1014
1015 #define DEFINE_WAIT_FUNC(name, function)                                \
1016         wait_queue_t name = {                                           \
1017                 .private        = current,                              \
1018                 .func           = function,                             \
1019                 .task_list      = LIST_HEAD_INIT((name).task_list),     \
1020         }
1021
1022 #define DEFINE_WAIT(name) DEFINE_WAIT_FUNC(name, autoremove_wake_function)
1023
1024 #define DEFINE_WAIT_BIT(name, word, bit)                                \
1025         struct wait_bit_queue name = {                                  \
1026                 .key = __WAIT_BIT_KEY_INITIALIZER(word, bit),           \
1027                 .wait   = {                                             \
1028                         .private        = current,                      \
1029                         .func           = wake_bit_function,            \
1030                         .task_list      =                               \
1031                                 LIST_HEAD_INIT((name).wait.task_list),  \
1032                 },                                                      \
1033         }
1034
1035 #define init_wait(wait)                                                 \
1036         do {                                                            \
1037                 (wait)->private = current;                              \
1038                 (wait)->func = autoremove_wake_function;                \
1039                 INIT_LIST_HEAD(&(wait)->task_list);                     \
1040                 (wait)->flags = 0;                                      \
1041         } while (0)
1042
1043
1044 extern int bit_wait(struct wait_bit_key *, int);
1045 extern int bit_wait_io(struct wait_bit_key *, int);
1046 extern int bit_wait_timeout(struct wait_bit_key *, int);
1047 extern int bit_wait_io_timeout(struct wait_bit_key *, int);
1048
1049 /**
1050  * wait_on_bit - wait for a bit to be cleared
1051  * @word: the word being waited on, a kernel virtual address
1052  * @bit: the bit of the word being waited on
1053  * @mode: the task state to sleep in
1054  *
1055  * There is a standard hashed waitqueue table for generic use. This
1056  * is the part of the hashtable's accessor API that waits on a bit.
1057  * For instance, if one were to have waiters on a bitflag, one would
1058  * call wait_on_bit() in threads waiting for the bit to clear.
1059  * One uses wait_on_bit() where one is waiting for the bit to clear,
1060  * but has no intention of setting it.
1061  * Returned value will be zero if the bit was cleared, or non-zero
1062  * if the process received a signal and the mode permitted wakeup
1063  * on that signal.
1064  */
1065 static inline int
1066 wait_on_bit(unsigned long *word, int bit, 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,
1072                                        bit_wait,
1073                                        mode);
1074 }
1075
1076 /**
1077  * wait_on_bit_io - wait for a bit to be cleared
1078  * @word: the word being waited on, a kernel virtual address
1079  * @bit: the bit of the word being waited on
1080  * @mode: the task state to sleep in
1081  *
1082  * Use the standard hashed waitqueue table to wait for a bit
1083  * to be cleared.  This is similar to wait_on_bit(), but calls
1084  * io_schedule() instead of schedule() for the actual waiting.
1085  *
1086  * Returned value will be zero if the bit was cleared, or non-zero
1087  * if the process received a signal and the mode permitted wakeup
1088  * on that signal.
1089  */
1090 static inline int
1091 wait_on_bit_io(unsigned long *word, int bit, unsigned mode)
1092 {
1093         might_sleep();
1094         if (!test_bit(bit, word))
1095                 return 0;
1096         return out_of_line_wait_on_bit(word, bit,
1097                                        bit_wait_io,
1098                                        mode);
1099 }
1100
1101 /**
1102  * wait_on_bit_timeout - wait for a bit to be cleared or a timeout elapses
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  * @timeout: timeout, in jiffies
1107  *
1108  * Use the standard hashed waitqueue table to wait for a bit
1109  * to be cleared. This is similar to wait_on_bit(), except also takes a
1110  * timeout parameter.
1111  *
1112  * Returned value will be zero if the bit was cleared before the
1113  * @timeout elapsed, or non-zero if the @timeout elapsed or process
1114  * received a signal and the mode permitted wakeup on that signal.
1115  */
1116 static inline int
1117 wait_on_bit_timeout(unsigned long *word, int bit, unsigned mode,
1118                     unsigned long timeout)
1119 {
1120         might_sleep();
1121         if (!test_bit(bit, word))
1122                 return 0;
1123         return out_of_line_wait_on_bit_timeout(word, bit,
1124                                                bit_wait_timeout,
1125                                                mode, timeout);
1126 }
1127
1128 /**
1129  * wait_on_bit_action - wait for a bit to be cleared
1130  * @word: the word being waited on, a kernel virtual address
1131  * @bit: the bit of the word being waited on
1132  * @action: the function used to sleep, which may take special actions
1133  * @mode: the task state to sleep in
1134  *
1135  * Use the standard hashed waitqueue table to wait for a bit
1136  * to be cleared, and allow the waiting action to be specified.
1137  * This is like wait_on_bit() but allows fine control of how the waiting
1138  * is done.
1139  *
1140  * Returned value will be zero if the bit was cleared, or non-zero
1141  * if the process received a signal and the mode permitted wakeup
1142  * on that signal.
1143  */
1144 static inline int
1145 wait_on_bit_action(unsigned long *word, int bit, wait_bit_action_f *action,
1146                    unsigned mode)
1147 {
1148         might_sleep();
1149         if (!test_bit(bit, word))
1150                 return 0;
1151         return out_of_line_wait_on_bit(word, bit, action, mode);
1152 }
1153
1154 /**
1155  * wait_on_bit_lock - wait for a bit to be cleared, when wanting to set it
1156  * @word: the word being waited on, a kernel virtual address
1157  * @bit: the bit of the word being waited on
1158  * @mode: the task state to sleep in
1159  *
1160  * There is a standard hashed waitqueue table for generic use. This
1161  * is the part of the hashtable's accessor API that waits on a bit
1162  * when one intends to set it, for instance, trying to lock bitflags.
1163  * For instance, if one were to have waiters trying to set bitflag
1164  * and waiting for it to clear before setting it, one would call
1165  * wait_on_bit() in threads waiting to be able to set the bit.
1166  * One uses wait_on_bit_lock() where one is waiting for the bit to
1167  * clear with the intention of setting it, and when done, clearing it.
1168  *
1169  * Returns zero if the bit was (eventually) found to be clear and was
1170  * set.  Returns non-zero if a signal was delivered to the process and
1171  * the @mode allows that signal to wake the process.
1172  */
1173 static inline int
1174 wait_on_bit_lock(unsigned long *word, int bit, unsigned mode)
1175 {
1176         might_sleep();
1177         if (!test_and_set_bit(bit, word))
1178                 return 0;
1179         return out_of_line_wait_on_bit_lock(word, bit, bit_wait, mode);
1180 }
1181
1182 /**
1183  * wait_on_bit_lock_io - wait for a bit to be cleared, when wanting to set it
1184  * @word: the word being waited on, a kernel virtual address
1185  * @bit: the bit of the word being waited on
1186  * @mode: the task state to sleep in
1187  *
1188  * Use the standard hashed waitqueue table to wait for a bit
1189  * to be cleared and then to atomically set it.  This is similar
1190  * to wait_on_bit(), but calls io_schedule() instead of schedule()
1191  * for the actual waiting.
1192  *
1193  * Returns zero if the bit was (eventually) found to be clear and was
1194  * set.  Returns non-zero if a signal was delivered to the process and
1195  * the @mode allows that signal to wake the process.
1196  */
1197 static inline int
1198 wait_on_bit_lock_io(unsigned long *word, int bit, unsigned mode)
1199 {
1200         might_sleep();
1201         if (!test_and_set_bit(bit, word))
1202                 return 0;
1203         return out_of_line_wait_on_bit_lock(word, bit, bit_wait_io, mode);
1204 }
1205
1206 /**
1207  * wait_on_bit_lock_action - wait for a bit to be cleared, when wanting to set it
1208  * @word: the word being waited on, a kernel virtual address
1209  * @bit: the bit of the word being waited on
1210  * @action: the function used to sleep, which may take special actions
1211  * @mode: the task state to sleep in
1212  *
1213  * Use the standard hashed waitqueue table to wait for a bit
1214  * to be cleared and then to set it, and allow the waiting action
1215  * to be specified.
1216  * This is like wait_on_bit() but allows fine control of how the waiting
1217  * is done.
1218  *
1219  * Returns zero if the bit was (eventually) found to be clear and was
1220  * set.  Returns non-zero if a signal was delivered to the process and
1221  * the @mode allows that signal to wake the process.
1222  */
1223 static inline int
1224 wait_on_bit_lock_action(unsigned long *word, int bit, wait_bit_action_f *action,
1225                         unsigned mode)
1226 {
1227         might_sleep();
1228         if (!test_and_set_bit(bit, word))
1229                 return 0;
1230         return out_of_line_wait_on_bit_lock(word, bit, action, mode);
1231 }
1232
1233 /**
1234  * wait_on_atomic_t - Wait for an atomic_t to become 0
1235  * @val: The atomic value being waited on, a kernel virtual address
1236  * @action: the function used to sleep, which may take special actions
1237  * @mode: the task state to sleep in
1238  *
1239  * Wait for an atomic_t to become 0.  We abuse the bit-wait waitqueue table for
1240  * the purpose of getting a waitqueue, but we set the key to a bit number
1241  * outside of the target 'word'.
1242  */
1243 static inline
1244 int wait_on_atomic_t(atomic_t *val, int (*action)(atomic_t *), unsigned mode)
1245 {
1246         might_sleep();
1247         if (atomic_read(val) == 0)
1248                 return 0;
1249         return out_of_line_wait_on_atomic_t(val, action, mode);
1250 }
1251
1252 #endif /* _LINUX_WAIT_H */