include/linux/wait.h

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