linux/include/linux/wait.h
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   1#ifndef _LINUX_WAIT_H
   2#define _LINUX_WAIT_H
   3
   4#define WNOHANG         0x00000001
   5#define WUNTRACED       0x00000002
   6#define WSTOPPED        WUNTRACED
   7#define WEXITED         0x00000004
   8#define WCONTINUED      0x00000008
   9#define WNOWAIT         0x01000000      /* Don't reap, just poll status.  */
  10
  11#define __WNOTHREAD     0x20000000      /* Don't wait on children of other threads in this group */
  12#define __WALL          0x40000000      /* Wait on all children, regardless of type */
  13#define __WCLONE        0x80000000      /* Wait only on non-SIGCHLD children */
  14
  15/* First argument to waitid: */
  16#define P_ALL           0
  17#define P_PID           1
  18#define P_PGID          2
  19
  20#ifdef __KERNEL__
  21
  22#include <linux/list.h>
  23#include <linux/stddef.h>
  24#include <linux/spinlock.h>
  25#include <asm/current.h>
  26
  27typedef struct __wait_queue wait_queue_t;
  28typedef int (*wait_queue_func_t)(wait_queue_t *wait, unsigned mode, int flags, void *key);
  29int default_wake_function(wait_queue_t *wait, unsigned mode, int flags, void *key);
  30
  31struct __wait_queue {
  32        unsigned int flags;
  33#define WQ_FLAG_EXCLUSIVE       0x01
  34        void *private;
  35        wait_queue_func_t func;
  36        struct list_head task_list;
  37};
  38
  39struct wait_bit_key {
  40        void *flags;
  41        int bit_nr;
  42};
  43
  44struct wait_bit_queue {
  45        struct wait_bit_key key;
  46        wait_queue_t wait;
  47};
  48
  49struct __wait_queue_head {
  50        spinlock_t lock;
  51        struct list_head task_list;
  52};
  53typedef struct __wait_queue_head wait_queue_head_t;
  54
  55struct task_struct;
  56
  57/*
  58 * Macros for declaration and initialisaton of the datatypes
  59 */
  60
  61#define __WAITQUEUE_INITIALIZER(name, tsk) {                            \
  62        .private        = tsk,                                          \
  63        .func           = default_wake_function,                        \
  64        .task_list      = { NULL, NULL } }
  65
  66#define DECLARE_WAITQUEUE(name, tsk)                                    \
  67        wait_queue_t name = __WAITQUEUE_INITIALIZER(name, tsk)
  68
  69#define __WAIT_QUEUE_HEAD_INITIALIZER(name) {                           \
  70        .lock           = __SPIN_LOCK_UNLOCKED(name.lock),              \
  71        .task_list      = { &(name).task_list, &(name).task_list } }
  72
  73#define DECLARE_WAIT_QUEUE_HEAD(name) \
  74        wait_queue_head_t name = __WAIT_QUEUE_HEAD_INITIALIZER(name)
  75
  76#define __WAIT_BIT_KEY_INITIALIZER(word, bit)                           \
  77        { .flags = word, .bit_nr = bit, }
  78
  79extern void __init_waitqueue_head(wait_queue_head_t *q, const char *name, struct lock_class_key *);
  80
  81#define init_waitqueue_head(q)                          \
  82        do {                                            \
  83                static struct lock_class_key __key;     \
  84                                                        \
  85                __init_waitqueue_head((q), #q, &__key); \
  86        } while (0)
  87
  88#ifdef CONFIG_LOCKDEP
  89# define __WAIT_QUEUE_HEAD_INIT_ONSTACK(name) \
  90        ({ init_waitqueue_head(&name); name; })
  91# define DECLARE_WAIT_QUEUE_HEAD_ONSTACK(name) \
  92        wait_queue_head_t name = __WAIT_QUEUE_HEAD_INIT_ONSTACK(name)
  93#else
  94# define DECLARE_WAIT_QUEUE_HEAD_ONSTACK(name) DECLARE_WAIT_QUEUE_HEAD(name)
  95#endif
  96
  97static inline void init_waitqueue_entry(wait_queue_t *q, struct task_struct *p)
  98{
  99        q->flags = 0;
 100        q->private = p;
 101        q->func = default_wake_function;
 102}
 103
 104static inline void init_waitqueue_func_entry(wait_queue_t *q,
 105                                        wait_queue_func_t func)
 106{
 107        q->flags = 0;
 108        q->private = NULL;
 109        q->func = func;
 110}
 111
 112static inline int waitqueue_active(wait_queue_head_t *q)
 113{
 114        return !list_empty(&q->task_list);
 115}
 116
 117extern void add_wait_queue(wait_queue_head_t *q, wait_queue_t *wait);
 118extern void add_wait_queue_exclusive(wait_queue_head_t *q, wait_queue_t *wait);
 119extern void remove_wait_queue(wait_queue_head_t *q, wait_queue_t *wait);
 120
 121static inline void __add_wait_queue(wait_queue_head_t *head, wait_queue_t *new)
 122{
 123        list_add(&new->task_list, &head->task_list);
 124}
 125
 126/*
 127 * Used for wake-one threads:
 128 */
 129static inline void __add_wait_queue_exclusive(wait_queue_head_t *q,
 130                                              wait_queue_t *wait)
 131{
 132        wait->flags |= WQ_FLAG_EXCLUSIVE;
 133        __add_wait_queue(q, wait);
 134}
 135
 136static inline void __add_wait_queue_tail(wait_queue_head_t *head,
 137                                         wait_queue_t *new)
 138{
 139        list_add_tail(&new->task_list, &head->task_list);
 140}
 141
 142static inline void __add_wait_queue_tail_exclusive(wait_queue_head_t *q,
 143                                              wait_queue_t *wait)
 144{
 145        wait->flags |= WQ_FLAG_EXCLUSIVE;
 146        __add_wait_queue_tail(q, wait);
 147}
 148
 149static inline void __remove_wait_queue(wait_queue_head_t *head,
 150                                                        wait_queue_t *old)
 151{
 152        list_del(&old->task_list);
 153}
 154
 155void __wake_up(wait_queue_head_t *q, unsigned int mode, int nr, void *key);
 156void __wake_up_locked_key(wait_queue_head_t *q, unsigned int mode, void *key);
 157void __wake_up_sync_key(wait_queue_head_t *q, unsigned int mode, int nr,
 158                        void *key);
 159void __wake_up_locked(wait_queue_head_t *q, unsigned int mode, int nr);
 160void __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr);
 161void __wake_up_bit(wait_queue_head_t *, void *, int);
 162int __wait_on_bit(wait_queue_head_t *, struct wait_bit_queue *, int (*)(void *), unsigned);
 163int __wait_on_bit_lock(wait_queue_head_t *, struct wait_bit_queue *, int (*)(void *), unsigned);
 164void wake_up_bit(void *, int);
 165int out_of_line_wait_on_bit(void *, int, int (*)(void *), unsigned);
 166int out_of_line_wait_on_bit_lock(void *, int, int (*)(void *), unsigned);
 167wait_queue_head_t *bit_waitqueue(void *, int);
 168
 169#define wake_up(x)                      __wake_up(x, TASK_NORMAL, 1, NULL)
 170#define wake_up_nr(x, nr)               __wake_up(x, TASK_NORMAL, nr, NULL)
 171#define wake_up_all(x)                  __wake_up(x, TASK_NORMAL, 0, NULL)
 172#define wake_up_locked(x)               __wake_up_locked((x), TASK_NORMAL, 1)
 173#define wake_up_all_locked(x)           __wake_up_locked((x), TASK_NORMAL, 0)
 174
 175#define wake_up_interruptible(x)        __wake_up(x, TASK_INTERRUPTIBLE, 1, NULL)
 176#define wake_up_interruptible_nr(x, nr) __wake_up(x, TASK_INTERRUPTIBLE, nr, NULL)
 177#define wake_up_interruptible_all(x)    __wake_up(x, TASK_INTERRUPTIBLE, 0, NULL)
 178#define wake_up_interruptible_sync(x)   __wake_up_sync((x), TASK_INTERRUPTIBLE, 1)
 179
 180/*
 181 * Wakeup macros to be used to report events to the targets.
 182 */
 183#define wake_up_poll(x, m)                              \
 184        __wake_up(x, TASK_NORMAL, 1, (void *) (m))
 185#define wake_up_locked_poll(x, m)                               \
 186        __wake_up_locked_key((x), TASK_NORMAL, (void *) (m))
 187#define wake_up_interruptible_poll(x, m)                        \
 188        __wake_up(x, TASK_INTERRUPTIBLE, 1, (void *) (m))
 189#define wake_up_interruptible_sync_poll(x, m)                           \
 190        __wake_up_sync_key((x), TASK_INTERRUPTIBLE, 1, (void *) (m))
 191
 192#define __wait_event(wq, condition)                                     \
 193do {                                                                    \
 194        DEFINE_WAIT(__wait);                                            \
 195                                                                        \
 196        for (;;) {                                                      \
 197                prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE);    \
 198                if (condition)                                          \
 199                        break;                                          \
 200                schedule();                                             \
 201        }                                                               \
 202        finish_wait(&wq, &__wait);                                      \
 203} while (0)
 204
 205/**
 206 * wait_event - sleep until a condition gets true
 207 * @wq: the waitqueue to wait on
 208 * @condition: a C expression for the event to wait for
 209 *
 210 * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 211 * @condition evaluates to true. The @condition is checked each time
 212 * the waitqueue @wq is woken up.
 213 *
 214 * wake_up() has to be called after changing any variable that could
 215 * change the result of the wait condition.
 216 */
 217#define wait_event(wq, condition)                                       \
 218do {                                                                    \
 219        if (condition)                                                  \
 220                break;                                                  \
 221        __wait_event(wq, condition);                                    \
 222} while (0)
 223
 224#define __wait_event_timeout(wq, condition, ret)                        \
 225do {                                                                    \
 226        DEFINE_WAIT(__wait);                                            \
 227                                                                        \
 228        for (;;) {                                                      \
 229                prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE);    \
 230                if (condition)                                          \
 231                        break;                                          \
 232                ret = schedule_timeout(ret);                            \
 233                if (!ret)                                               \
 234                        break;                                          \
 235        }                                                               \
 236        finish_wait(&wq, &__wait);                                      \
 237} while (0)
 238
 239/**
 240 * wait_event_timeout - sleep until a condition gets true or a timeout elapses
 241 * @wq: the waitqueue to wait on
 242 * @condition: a C expression for the event to wait for
 243 * @timeout: timeout, in jiffies
 244 *
 245 * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 246 * @condition evaluates to true. The @condition is checked each time
 247 * the waitqueue @wq is woken up.
 248 *
 249 * wake_up() has to be called after changing any variable that could
 250 * change the result of the wait condition.
 251 *
 252 * The function returns 0 if the @timeout elapsed, and the remaining
 253 * jiffies if the condition evaluated to true before the timeout elapsed.
 254 */
 255#define wait_event_timeout(wq, condition, timeout)                      \
 256({                                                                      \
 257        long __ret = timeout;                                           \
 258        if (!(condition))                                               \
 259                __wait_event_timeout(wq, condition, __ret);             \
 260        __ret;                                                          \
 261})
 262
 263#define __wait_event_interruptible(wq, condition, ret)                  \
 264do {                                                                    \
 265        DEFINE_WAIT(__wait);                                            \
 266                                                                        \
 267        for (;;) {                                                      \
 268                prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE);      \
 269                if (condition)                                          \
 270                        break;                                          \
 271                if (!signal_pending(current)) {                         \
 272                        schedule();                                     \
 273                        continue;                                       \
 274                }                                                       \
 275                ret = -ERESTARTSYS;                                     \
 276                break;                                                  \
 277        }                                                               \
 278        finish_wait(&wq, &__wait);                                      \
 279} while (0)
 280
 281/**
 282 * wait_event_interruptible - sleep until a condition gets true
 283 * @wq: the waitqueue to wait on
 284 * @condition: a C expression for the event to wait for
 285 *
 286 * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 287 * @condition evaluates to true or a signal is received.
 288 * The @condition is checked each time the waitqueue @wq is woken up.
 289 *
 290 * wake_up() has to be called after changing any variable that could
 291 * change the result of the wait condition.
 292 *
 293 * The function will return -ERESTARTSYS if it was interrupted by a
 294 * signal and 0 if @condition evaluated to true.
 295 */
 296#define wait_event_interruptible(wq, condition)                         \
 297({                                                                      \
 298        int __ret = 0;                                                  \
 299        if (!(condition))                                               \
 300                __wait_event_interruptible(wq, condition, __ret);       \
 301        __ret;                                                          \
 302})
 303
 304#define __wait_event_interruptible_timeout(wq, condition, ret)          \
 305do {                                                                    \
 306        DEFINE_WAIT(__wait);                                            \
 307                                                                        \
 308        for (;;) {                                                      \
 309                prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE);      \
 310                if (condition)                                          \
 311                        break;                                          \
 312                if (!signal_pending(current)) {                         \
 313                        ret = schedule_timeout(ret);                    \
 314                        if (!ret)                                       \
 315                                break;                                  \
 316                        continue;                                       \
 317                }                                                       \
 318                ret = -ERESTARTSYS;                                     \
 319                break;                                                  \
 320        }                                                               \
 321        finish_wait(&wq, &__wait);                                      \
 322} while (0)
 323
 324/**
 325 * wait_event_interruptible_timeout - sleep until a condition gets true or a timeout elapses
 326 * @wq: the waitqueue to wait on
 327 * @condition: a C expression for the event to wait for
 328 * @timeout: timeout, in jiffies
 329 *
 330 * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 331 * @condition evaluates to true or a signal is received.
 332 * The @condition is checked each time the waitqueue @wq is woken up.
 333 *
 334 * wake_up() has to be called after changing any variable that could
 335 * change the result of the wait condition.
 336 *
 337 * The function returns 0 if the @timeout elapsed, -ERESTARTSYS if it
 338 * was interrupted by a signal, and the remaining jiffies otherwise
 339 * if the condition evaluated to true before the timeout elapsed.
 340 */
 341#define wait_event_interruptible_timeout(wq, condition, timeout)        \
 342({                                                                      \
 343        long __ret = timeout;                                           \
 344        if (!(condition))                                               \
 345                __wait_event_interruptible_timeout(wq, condition, __ret); \
 346        __ret;                                                          \
 347})
 348
 349#define __wait_event_interruptible_exclusive(wq, condition, ret)        \
 350do {                                                                    \
 351        DEFINE_WAIT(__wait);                                            \
 352                                                                        \
 353        for (;;) {                                                      \
 354                prepare_to_wait_exclusive(&wq, &__wait,                 \
 355                                        TASK_INTERRUPTIBLE);            \
 356                if (condition) {                                        \
 357                        finish_wait(&wq, &__wait);                      \
 358                        break;                                          \
 359                }                                                       \
 360                if (!signal_pending(current)) {                         \
 361                        schedule();                                     \
 362                        continue;                                       \
 363                }                                                       \
 364                ret = -ERESTARTSYS;                                     \
 365                abort_exclusive_wait(&wq, &__wait,                      \
 366                                TASK_INTERRUPTIBLE, NULL);              \
 367                break;                                                  \
 368        }                                                               \
 369} while (0)
 370
 371#define wait_event_interruptible_exclusive(wq, condition)               \
 372({                                                                      \
 373        int __ret = 0;                                                  \
 374        if (!(condition))                                               \
 375                __wait_event_interruptible_exclusive(wq, condition, __ret);\
 376        __ret;                                                          \
 377})
 378
 379
 380#define __wait_event_interruptible_locked(wq, condition, exclusive, irq) \
 381({                                                                      \
 382        int __ret = 0;                                                  \
 383        DEFINE_WAIT(__wait);                                            \
 384        if (exclusive)                                                  \
 385                __wait.flags |= WQ_FLAG_EXCLUSIVE;                      \
 386        do {                                                            \
 387                if (likely(list_empty(&__wait.task_list)))              \
 388                        __add_wait_queue_tail(&(wq), &__wait);          \
 389                set_current_state(TASK_INTERRUPTIBLE);                  \
 390                if (signal_pending(current)) {                          \
 391                        __ret = -ERESTARTSYS;                           \
 392                        break;                                          \
 393                }                                                       \
 394                if (irq)                                                \
 395                        spin_unlock_irq(&(wq).lock);                    \
 396                else                                                    \
 397                        spin_unlock(&(wq).lock);                        \
 398                schedule();                                             \
 399                if (irq)                                                \
 400                        spin_lock_irq(&(wq).lock);                      \
 401                else                                                    \
 402                        spin_lock(&(wq).lock);                          \
 403        } while (!(condition));                                         \
 404        __remove_wait_queue(&(wq), &__wait);                            \
 405        __set_current_state(TASK_RUNNING);                              \
 406        __ret;                                                          \
 407})
 408
 409
 410/**
 411 * wait_event_interruptible_locked - sleep until a condition gets true
 412 * @wq: the waitqueue to wait on
 413 * @condition: a C expression for the event to wait for
 414 *
 415 * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 416 * @condition evaluates to true or a signal is received.
 417 * The @condition is checked each time the waitqueue @wq is woken up.
 418 *
 419 * It must be called with wq.lock being held.  This spinlock is
 420 * unlocked while sleeping but @condition testing is done while lock
 421 * is held and when this macro exits the lock is held.
 422 *
 423 * The lock is locked/unlocked using spin_lock()/spin_unlock()
 424 * functions which must match the way they are locked/unlocked outside
 425 * of this macro.
 426 *
 427 * wake_up_locked() has to be called after changing any variable that could
 428 * change the result of the wait condition.
 429 *
 430 * The function will return -ERESTARTSYS if it was interrupted by a
 431 * signal and 0 if @condition evaluated to true.
 432 */
 433#define wait_event_interruptible_locked(wq, condition)                  \
 434        ((condition)                                                    \
 435         ? 0 : __wait_event_interruptible_locked(wq, condition, 0, 0))
 436
 437/**
 438 * wait_event_interruptible_locked_irq - sleep until a condition gets true
 439 * @wq: the waitqueue to wait on
 440 * @condition: a C expression for the event to wait for
 441 *
 442 * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 443 * @condition evaluates to true or a signal is received.
 444 * The @condition is checked each time the waitqueue @wq is woken up.
 445 *
 446 * It must be called with wq.lock being held.  This spinlock is
 447 * unlocked while sleeping but @condition testing is done while lock
 448 * is held and when this macro exits the lock is held.
 449 *
 450 * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq()
 451 * functions which must match the way they are locked/unlocked outside
 452 * of this macro.
 453 *
 454 * wake_up_locked() has to be called after changing any variable that could
 455 * change the result of the wait condition.
 456 *
 457 * The function will return -ERESTARTSYS if it was interrupted by a
 458 * signal and 0 if @condition evaluated to true.
 459 */
 460#define wait_event_interruptible_locked_irq(wq, condition)              \
 461        ((condition)                                                    \
 462         ? 0 : __wait_event_interruptible_locked(wq, condition, 0, 1))
 463
 464/**
 465 * wait_event_interruptible_exclusive_locked - sleep exclusively until a condition gets true
 466 * @wq: the waitqueue to wait on
 467 * @condition: a C expression for the event to wait for
 468 *
 469 * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 470 * @condition evaluates to true or a signal is received.
 471 * The @condition is checked each time the waitqueue @wq is woken up.
 472 *
 473 * It must be called with wq.lock being held.  This spinlock is
 474 * unlocked while sleeping but @condition testing is done while lock
 475 * is held and when this macro exits the lock is held.
 476 *
 477 * The lock is locked/unlocked using spin_lock()/spin_unlock()
 478 * functions which must match the way they are locked/unlocked outside
 479 * of this macro.
 480 *
 481 * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
 482 * set thus when other process waits process on the list if this
 483 * process is awaken further processes are not considered.
 484 *
 485 * wake_up_locked() has to be called after changing any variable that could
 486 * change the result of the wait condition.
 487 *
 488 * The function will return -ERESTARTSYS if it was interrupted by a
 489 * signal and 0 if @condition evaluated to true.
 490 */
 491#define wait_event_interruptible_exclusive_locked(wq, condition)        \
 492        ((condition)                                                    \
 493         ? 0 : __wait_event_interruptible_locked(wq, condition, 1, 0))
 494
 495/**
 496 * wait_event_interruptible_exclusive_locked_irq - sleep until a condition gets true
 497 * @wq: the waitqueue to wait on
 498 * @condition: a C expression for the event to wait for
 499 *
 500 * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 501 * @condition evaluates to true or a signal is received.
 502 * The @condition is checked each time the waitqueue @wq is woken up.
 503 *
 504 * It must be called with wq.lock being held.  This spinlock is
 505 * unlocked while sleeping but @condition testing is done while lock
 506 * is held and when this macro exits the lock is held.
 507 *
 508 * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq()
 509 * functions which must match the way they are locked/unlocked outside
 510 * of this macro.
 511 *
 512 * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
 513 * set thus when other process waits process on the list if this
 514 * process is awaken further processes are not considered.
 515 *
 516 * wake_up_locked() has to be called after changing any variable that could
 517 * change the result of the wait condition.
 518 *
 519 * The function will return -ERESTARTSYS if it was interrupted by a
 520 * signal and 0 if @condition evaluated to true.
 521 */
 522#define wait_event_interruptible_exclusive_locked_irq(wq, condition)    \
 523        ((condition)                                                    \
 524         ? 0 : __wait_event_interruptible_locked(wq, condition, 1, 1))
 525
 526
 527
 528#define __wait_event_killable(wq, condition, ret)                       \
 529do {                                                                    \
 530        DEFINE_WAIT(__wait);                                            \
 531                                                                        \
 532        for (;;) {                                                      \
 533                prepare_to_wait(&wq, &__wait, TASK_KILLABLE);           \
 534                if (condition)                                          \
 535                        break;                                          \
 536                if (!fatal_signal_pending(current)) {                   \
 537                        schedule();                                     \
 538                        continue;                                       \
 539                }                                                       \
 540                ret = -ERESTARTSYS;                                     \
 541                break;                                                  \
 542        }                                                               \
 543        finish_wait(&wq, &__wait);                                      \
 544} while (0)
 545
 546/**
 547 * wait_event_killable - sleep until a condition gets true
 548 * @wq: the waitqueue to wait on
 549 * @condition: a C expression for the event to wait for
 550 *
 551 * The process is put to sleep (TASK_KILLABLE) until the
 552 * @condition evaluates to true or a signal is received.
 553 * The @condition is checked each time the waitqueue @wq is woken up.
 554 *
 555 * wake_up() has to be called after changing any variable that could
 556 * change the result of the wait condition.
 557 *
 558 * The function will return -ERESTARTSYS if it was interrupted by a
 559 * signal and 0 if @condition evaluated to true.
 560 */
 561#define wait_event_killable(wq, condition)                              \
 562({                                                                      \
 563        int __ret = 0;                                                  \
 564        if (!(condition))                                               \
 565                __wait_event_killable(wq, condition, __ret);            \
 566        __ret;                                                          \
 567})
 568
 569/*
 570 * These are the old interfaces to sleep waiting for an event.
 571 * They are racy.  DO NOT use them, use the wait_event* interfaces above.
 572 * We plan to remove these interfaces.
 573 */
 574extern void sleep_on(wait_queue_head_t *q);
 575extern long sleep_on_timeout(wait_queue_head_t *q,
 576                                      signed long timeout);
 577extern void interruptible_sleep_on(wait_queue_head_t *q);
 578extern long interruptible_sleep_on_timeout(wait_queue_head_t *q,
 579                                           signed long timeout);
 580
 581/*
 582 * Waitqueues which are removed from the waitqueue_head at wakeup time
 583 */
 584void prepare_to_wait(wait_queue_head_t *q, wait_queue_t *wait, int state);
 585void prepare_to_wait_exclusive(wait_queue_head_t *q, wait_queue_t *wait, int state);
 586void finish_wait(wait_queue_head_t *q, wait_queue_t *wait);
 587void abort_exclusive_wait(wait_queue_head_t *q, wait_queue_t *wait,
 588                        unsigned int mode, void *key);
 589int autoremove_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 590int wake_bit_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 591
 592#define DEFINE_WAIT_FUNC(name, function)                                \
 593        wait_queue_t name = {                                           \
 594                .private        = current,                              \
 595                .func           = function,                             \
 596                .task_list      = LIST_HEAD_INIT((name).task_list),     \
 597        }
 598
 599#define DEFINE_WAIT(name) DEFINE_WAIT_FUNC(name, autoremove_wake_function)
 600
 601#define DEFINE_WAIT_BIT(name, word, bit)                                \
 602        struct wait_bit_queue name = {                                  \
 603                .key = __WAIT_BIT_KEY_INITIALIZER(word, bit),           \
 604                .wait   = {                                             \
 605                        .private        = current,                      \
 606                        .func           = wake_bit_function,            \
 607                        .task_list      =                               \
 608                                LIST_HEAD_INIT((name).wait.task_list),  \
 609                },                                                      \
 610        }
 611
 612#define init_wait(wait)                                                 \
 613        do {                                                            \
 614                (wait)->private = current;                              \
 615                (wait)->func = autoremove_wake_function;                \
 616                INIT_LIST_HEAD(&(wait)->task_list);                     \
 617                (wait)->flags = 0;                                      \
 618        } while (0)
 619
 620/**
 621 * wait_on_bit - wait for a bit to be cleared
 622 * @word: the word being waited on, a kernel virtual address
 623 * @bit: the bit of the word being waited on
 624 * @action: the function used to sleep, which may take special actions
 625 * @mode: the task state to sleep in
 626 *
 627 * There is a standard hashed waitqueue table for generic use. This
 628 * is the part of the hashtable's accessor API that waits on a bit.
 629 * For instance, if one were to have waiters on a bitflag, one would
 630 * call wait_on_bit() in threads waiting for the bit to clear.
 631 * One uses wait_on_bit() where one is waiting for the bit to clear,
 632 * but has no intention of setting it.
 633 */
 634static inline int wait_on_bit(void *word, int bit,
 635                                int (*action)(void *), unsigned mode)
 636{
 637        if (!test_bit(bit, word))
 638                return 0;
 639        return out_of_line_wait_on_bit(word, bit, action, mode);
 640}
 641
 642/**
 643 * wait_on_bit_lock - wait for a bit to be cleared, when wanting to set it
 644 * @word: the word being waited on, a kernel virtual address
 645 * @bit: the bit of the word being waited on
 646 * @action: the function used to sleep, which may take special actions
 647 * @mode: the task state to sleep in
 648 *
 649 * There is a standard hashed waitqueue table for generic use. This
 650 * is the part of the hashtable's accessor API that waits on a bit
 651 * when one intends to set it, for instance, trying to lock bitflags.
 652 * For instance, if one were to have waiters trying to set bitflag
 653 * and waiting for it to clear before setting it, one would call
 654 * wait_on_bit() in threads waiting to be able to set the bit.
 655 * One uses wait_on_bit_lock() where one is waiting for the bit to
 656 * clear with the intention of setting it, and when done, clearing it.
 657 */
 658static inline int wait_on_bit_lock(void *word, int bit,
 659                                int (*action)(void *), unsigned mode)
 660{
 661        if (!test_and_set_bit(bit, word))
 662                return 0;
 663        return out_of_line_wait_on_bit_lock(word, bit, action, mode);
 664}
 665        
 666#endif /* __KERNEL__ */
 667
 668#endif
 669
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