include/linux/wait.h

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