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 sync, void *key);
  30 int default_wake_function(wait_queue_t *wait, unsigned mode, int sync, 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);
  81
  82 #ifdef CONFIG_LOCKDEP
  83 # define __WAIT_QUEUE_HEAD_INIT_ONSTACK(name) \
  84         ({ init_waitqueue_head(&name); name; })
  85 # define DECLARE_WAIT_QUEUE_HEAD_ONSTACK(name) \
  86         wait_queue_head_t name = __WAIT_QUEUE_HEAD_INIT_ONSTACK(name)
  87 #else
  88 # define DECLARE_WAIT_QUEUE_HEAD_ONSTACK(name) DECLARE_WAIT_QUEUE_HEAD(name)
  89 #endif
  90
  91 static inline void init_waitqueue_entry(wait_queue_t *q, struct task_struct *p)
  92 {
  93         q->flags = 0;
  94         q->private = p;
  95         q->func = default_wake_function;
  96 }
  97
  98 static inline void init_waitqueue_func_entry(wait_queue_t *q,
  99                                         wait_queue_func_t func)
 100 {
 101         q->flags = 0;
 102         q->private = NULL;
 103         q->func = func;
 104 }
 105
 106 static inline int waitqueue_active(wait_queue_head_t *q)
 107 {
 108         return !list_empty(&q->task_list);
 109 }
 110
 111 /*
 112  * Used to distinguish between sync and async io wait context:
 113  * sync i/o typically specifies a NULL wait queue entry or a wait
 114  * queue entry bound to a task (current task) to wake up.
 115  * aio specifies a wait queue entry with an async notification
 116  * callback routine, not associated with any task.
 117  */
 118 #define is_sync_wait(wait)      (!(wait) || ((wait)->private))
 119
 120 extern void add_wait_queue(wait_queue_head_t *q, wait_queue_t *wait);
 121 extern void add_wait_queue_exclusive(wait_queue_head_t *q, wait_queue_t *wait);
 122 extern void remove_wait_queue(wait_queue_head_t *q, wait_queue_t *wait);
 123
 124 static inline void __add_wait_queue(wait_queue_head_t *head, wait_queue_t *new)
 125 {
 126         list_add(&new->task_list, &head->task_list);
 127 }
 128
 129 /*
 130  * Used for wake-one threads:
 131  */
 132 static inline void __add_wait_queue_tail(wait_queue_head_t *head,
 133                                                 wait_queue_t *new)
 134 {
 135         list_add_tail(&new->task_list, &head->task_list);
 136 }
 137
 138 static inline void __remove_wait_queue(wait_queue_head_t *head,
 139                                                         wait_queue_t *old)
 140 {
 141         list_del(&old->task_list);
 142 }
 143
 144 void __wake_up_common(wait_queue_head_t *q, unsigned int mode,
 145                         int nr_exclusive, int sync, void *key);
 146 void __wake_up(wait_queue_head_t *q, unsigned int mode, int nr, void *key);
 147 extern void __wake_up_locked(wait_queue_head_t *q, unsigned int mode);
 148 extern void __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr);
 149 void __wake_up_bit(wait_queue_head_t *, void *, int);
 150 int __wait_on_bit(wait_queue_head_t *, struct wait_bit_queue *, int (*)(void *), unsigned);
 151 int __wait_on_bit_lock(wait_queue_head_t *, struct wait_bit_queue *, int (*)(void *), unsigned);
 152 void wake_up_bit(void *, int);
 153 int out_of_line_wait_on_bit(void *, int, int (*)(void *), unsigned);
 154 int out_of_line_wait_on_bit_lock(void *, int, int (*)(void *), unsigned);
 155 wait_queue_head_t *bit_waitqueue(void *, int);
 156
 157 #define wake_up(x)                      __wake_up(x, TASK_NORMAL, 1, NULL)
 158 #define wake_up_nr(x, nr)               __wake_up(x, TASK_NORMAL, nr, NULL)
 159 #define wake_up_all(x)                  __wake_up(x, TASK_NORMAL, 0, NULL)
 160 #define wake_up_locked(x)               __wake_up_locked((x), TASK_NORMAL)
 161
 162 #define wake_up_interruptible(x)        __wake_up(x, TASK_INTERRUPTIBLE, 1, NULL)
 163 #define wake_up_interruptible_nr(x, nr) __wake_up(x, TASK_INTERRUPTIBLE, nr, NULL)
 164 #define wake_up_interruptible_all(x)    __wake_up(x, TASK_INTERRUPTIBLE, 0, NULL)
 165 #define wake_up_interruptible_sync(x)   __wake_up_sync((x), TASK_INTERRUPTIBLE, 1)
 166
 167 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 168 /*
 169  * macro to avoid include hell
 170  */
 171 #define wake_up_nested(x, s)                                            \
 172 do {                                                                    \
 173         unsigned long flags;                                            \
 174                                                                         \
 175         spin_lock_irqsave_nested(&(x)->lock, flags, (s));               \
 176         wake_up_locked(x);                                              \
 177         spin_unlock_irqrestore(&(x)->lock, flags);                      \
 178 } while (0)
 179 #else
 180 #define wake_up_nested(x, s)            wake_up(x)
 181 #endif
 182
 183 #define __wait_event(wq, condition)                                     \
 184 do {                                                                    \
 185         DEFINE_WAIT(__wait);                                            \
 186                                                                         \
 187         for (;;) {                                                      \
 188                 prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE);    \
 189                 if (condition)                                          \
 190                         break;                                          \
 191                 schedule();                                             \
 192         }                                                               \
 193         finish_wait(&wq, &__wait);                                      \
 194 } while (0)
 195
 196 /**
 197  * wait_event - sleep until a condition gets true
 198  * @wq: the waitqueue to wait on
 199  * @condition: a C expression for the event to wait for
 200  *
 201  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 202  * @condition evaluates to true. The @condition is checked each time
 203  * the waitqueue @wq is woken up.
 204  *
 205  * wake_up() has to be called after changing any variable that could
 206  * change the result of the wait condition.
 207  */
 208 #define wait_event(wq, condition)                                       \
 209 do {                                                                    \
 210         if (condition)                                                  \
 211                 break;                                                  \
 212         __wait_event(wq, condition);                                    \
 213 } while (0)
 214
 215 #define __wait_event_timeout(wq, condition, ret)                        \
 216 do {                                                                    \
 217         DEFINE_WAIT(__wait);                                            \
 218                                                                         \
 219         for (;;) {                                                      \
 220                 prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE);    \
 221                 if (condition)                                          \
 222                         break;                                          \
 223                 ret = schedule_timeout(ret);                            \
 224                 if (!ret)                                               \
 225                         break;                                          \
 226         }                                                               \
 227         finish_wait(&wq, &__wait);                                      \
 228 } while (0)
 229
 230 /**
 231  * wait_event_timeout - sleep until a condition gets true or a timeout elapses
 232  * @wq: the waitqueue to wait on
 233  * @condition: a C expression for the event to wait for
 234  * @timeout: timeout, in jiffies
 235  *
 236  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 237  * @condition evaluates to true. The @condition is checked each time
 238  * the waitqueue @wq is woken up.
 239  *
 240  * wake_up() has to be called after changing any variable that could
 241  * change the result of the wait condition.
 242  *
 243  * The function returns 0 if the @timeout elapsed, and the remaining
 244  * jiffies if the condition evaluated to true before the timeout elapsed.
 245  */
 246 #define wait_event_timeout(wq, condition, timeout)                      \
 247 ({                                                                      \
 248         long __ret = timeout;                                           \
 249         if (!(condition))                                               \
 250                 __wait_event_timeout(wq, condition, __ret);             \
 251         __ret;                                                          \
 252 })
 253
 254 #define __wait_event_interruptible(wq, condition, ret)                  \
 255 do {                                                                    \
 256         DEFINE_WAIT(__wait);                                            \
 257                                                                         \
 258         for (;;) {                                                      \
 259                 prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE);      \
 260                 if (condition)                                          \
 261                         break;                                          \
 262                 if (!signal_pending(current)) {                         \
 263                         schedule();                                     \
 264                         continue;                                       \
 265                 }                                                       \
 266                 ret = -ERESTARTSYS;                                     \
 267                 break;                                                  \
 268         }                                                               \
 269         finish_wait(&wq, &__wait);                                      \
 270 } while (0)
 271
 272 /**
 273  * wait_event_interruptible - sleep until a condition gets true
 274  * @wq: the waitqueue to wait on
 275  * @condition: a C expression for the event to wait for
 276  *
 277  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 278  * @condition evaluates to true or a signal is received.
 279  * The @condition is checked each time the waitqueue @wq is woken up.
 280  *
 281  * wake_up() has to be called after changing any variable that could
 282  * change the result of the wait condition.
 283  *
 284  * The function will return -ERESTARTSYS if it was interrupted by a
 285  * signal and 0 if @condition evaluated to true.
 286  */
 287 #define wait_event_interruptible(wq, condition)                         \
 288 ({                                                                      \
 289         int __ret = 0;                                                  \
 290         if (!(condition))                                               \
 291                 __wait_event_interruptible(wq, condition, __ret);       \
 292         __ret;                                                          \
 293 })
 294
 295 #define __wait_event_interruptible_timeout(wq, condition, ret)          \
 296 do {                                                                    \
 297         DEFINE_WAIT(__wait);                                            \
 298                                                                         \
 299         for (;;) {                                                      \
 300                 prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE);      \
 301                 if (condition)                                          \
 302                         break;                                          \
 303                 if (!signal_pending(current)) {                         \
 304                         ret = schedule_timeout(ret);                    \
 305                         if (!ret)                                       \
 306                                 break;                                  \
 307                         continue;                                       \
 308                 }                                                       \
 309                 ret = -ERESTARTSYS;                                     \
 310                 break;                                                  \
 311         }                                                               \
 312         finish_wait(&wq, &__wait);                                      \
 313 } while (0)
 314
 315 /**
 316  * wait_event_interruptible_timeout - sleep until a condition gets true or a timeout elapses
 317  * @wq: the waitqueue to wait on
 318  * @condition: a C expression for the event to wait for
 319  * @timeout: timeout, in jiffies
 320  *
 321  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 322  * @condition evaluates to true or a signal is received.
 323  * The @condition is checked each time the waitqueue @wq is woken up.
 324  *
 325  * wake_up() has to be called after changing any variable that could
 326  * change the result of the wait condition.
 327  *
 328  * The function returns 0 if the @timeout elapsed, -ERESTARTSYS if it
 329  * was interrupted by a signal, and the remaining jiffies otherwise
 330  * if the condition evaluated to true before the timeout elapsed.
 331  */
 332 #define wait_event_interruptible_timeout(wq, condition, timeout)        \
 333 ({                                                                      \
 334         long __ret = timeout;                                           \
 335         if (!(condition))                                               \
 336                 __wait_event_interruptible_timeout(wq, condition, __ret); \
 337         __ret;                                                          \
 338 })
 339
 340 #define __wait_event_interruptible_exclusive(wq, condition, ret)        \
 341 do {                                                                    \
 342         DEFINE_WAIT(__wait);                                            \
 343                                                                         \
 344         for (;;) {                                                      \
 345                 prepare_to_wait_exclusive(&wq, &__wait,                 \
 346                                         TASK_INTERRUPTIBLE);            \
 347                 if (condition) {                                        \
 348                         finish_wait(&wq, &__wait);                      \
 349                         break;                                          \
 350                 }                                                       \
 351                 if (!signal_pending(current)) {                         \
 352                         schedule();                                     \
 353                         continue;                                       \
 354                 }                                                       \
 355                 ret = -ERESTARTSYS;                                     \
 356                 abort_exclusive_wait(&wq, &__wait,                      \
 357                                 TASK_INTERRUPTIBLE, NULL);              \
 358                 break;                                                  \
 359         }                                                               \
 360 } while (0)
 361
 362 #define wait_event_interruptible_exclusive(wq, condition)               \
 363 ({                                                                      \
 364         int __ret = 0;                                                  \
 365         if (!(condition))                                               \
 366                 __wait_event_interruptible_exclusive(wq, condition, __ret);\
 367         __ret;                                                          \
 368 })
 369
 370 #define __wait_event_killable(wq, condition, ret)                       \
 371 do {                                                                    \
 372         DEFINE_WAIT(__wait);                                            \
 373                                                                         \
 374         for (;;) {                                                      \
 375                 prepare_to_wait(&wq, &__wait, TASK_KILLABLE);           \
 376                 if (condition)                                          \
 377                         break;                                          \
 378                 if (!fatal_signal_pending(current)) {                   \
 379                         schedule();                                     \
 380                         continue;                                       \
 381                 }                                                       \
 382                 ret = -ERESTARTSYS;                                     \
 383                 break;                                                  \
 384         }                                                               \
 385         finish_wait(&wq, &__wait);                                      \
 386 } while (0)
 387
 388 /**
 389  * wait_event_killable - sleep until a condition gets true
 390  * @wq: the waitqueue to wait on
 391  * @condition: a C expression for the event to wait for
 392  *
 393  * The process is put to sleep (TASK_KILLABLE) until the
 394  * @condition evaluates to true or a signal is received.
 395  * The @condition is checked each time the waitqueue @wq is woken up.
 396  *
 397  * wake_up() has to be called after changing any variable that could
 398  * change the result of the wait condition.
 399  *
 400  * The function will return -ERESTARTSYS if it was interrupted by a
 401  * signal and 0 if @condition evaluated to true.
 402  */
 403 #define wait_event_killable(wq, condition)                              \
 404 ({                                                                      \
 405         int __ret = 0;                                                  \
 406         if (!(condition))                                               \
 407                 __wait_event_killable(wq, condition, __ret);            \
 408         __ret;                                                          \
 409 })
 410
 411 /*
 412  * Must be called with the spinlock in the wait_queue_head_t held.
 413  */
 414 static inline void add_wait_queue_exclusive_locked(wait_queue_head_t *q,
 415                                                    wait_queue_t * wait)
 416 {
 417         wait->flags |= WQ_FLAG_EXCLUSIVE;
 418         __add_wait_queue_tail(q,  wait);
 419 }
 420
 421 /*
 422  * Must be called with the spinlock in the wait_queue_head_t held.
 423  */
 424 static inline void remove_wait_queue_locked(wait_queue_head_t *q,
 425                                             wait_queue_t * wait)
 426 {
 427         __remove_wait_queue(q,  wait);
 428 }
 429
 430 /*
 431  * These are the old interfaces to sleep waiting for an event.
 432  * They are racy.  DO NOT use them, use the wait_event* interfaces above.
 433  * We plan to remove these interfaces.
 434  */
 435 extern void sleep_on(wait_queue_head_t *q);
 436 extern long sleep_on_timeout(wait_queue_head_t *q,
 437                                       signed long timeout);
 438 extern void interruptible_sleep_on(wait_queue_head_t *q);
 439 extern long interruptible_sleep_on_timeout(wait_queue_head_t *q,
 440                                            signed long timeout);
 441
 442 /*
 443  * Waitqueues which are removed from the waitqueue_head at wakeup time
 444  */
 445 void prepare_to_wait(wait_queue_head_t *q, wait_queue_t *wait, int state);
 446 void prepare_to_wait_exclusive(wait_queue_head_t *q, wait_queue_t *wait, int state);
 447 void finish_wait(wait_queue_head_t *q, wait_queue_t *wait);
 448 void abort_exclusive_wait(wait_queue_head_t *q, wait_queue_t *wait,
 449                         unsigned int mode, void *key);
 450 int autoremove_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 451 int wake_bit_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 452
 453 #define DEFINE_WAIT(name)                                               \
 454         wait_queue_t name = {                                           \
 455                 .private        = current,                              \
 456                 .func           = autoremove_wake_function,             \
 457                 .task_list      = LIST_HEAD_INIT((name).task_list),     \
 458         }
 459
 460 #define DEFINE_WAIT_BIT(name, word, bit)                                \
 461         struct wait_bit_queue name = {                                  \
 462                 .key = __WAIT_BIT_KEY_INITIALIZER(word, bit),           \
 463                 .wait   = {                                             \
 464                         .private        = current,                      \
 465                         .func           = wake_bit_function,            \
 466                         .task_list      =                               \
 467                                 LIST_HEAD_INIT((name).wait.task_list),  \
 468                 },                                                      \
 469         }
 470
 471 #define init_wait(wait)                                                 \
 472         do {                                                            \
 473                 (wait)->private = current;                              \
 474                 (wait)->func = autoremove_wake_function;                \
 475                 INIT_LIST_HEAD(&(wait)->task_list);                     \
 476         } while (0)
 477
 478 /**
 479  * wait_on_bit - wait for a bit to be cleared
 480  * @word: the word being waited on, a kernel virtual address
 481  * @bit: the bit of the word being waited on
 482  * @action: the function used to sleep, which may take special actions
 483  * @mode: the task state to sleep in
 484  *
 485  * There is a standard hashed waitqueue table for generic use. This
 486  * is the part of the hashtable's accessor API that waits on a bit.
 487  * For instance, if one were to have waiters on a bitflag, one would
 488  * call wait_on_bit() in threads waiting for the bit to clear.
 489  * One uses wait_on_bit() where one is waiting for the bit to clear,
 490  * but has no intention of setting it.
 491  */
 492 static inline int wait_on_bit(void *word, int bit,
 493                                 int (*action)(void *), unsigned mode)
 494 {
 495         if (!test_bit(bit, word))
 496                 return 0;
 497         return out_of_line_wait_on_bit(word, bit, action, mode);
 498 }
 499
 500 /**
 501  * wait_on_bit_lock - wait for a bit to be cleared, when wanting to set it
 502  * @word: the word being waited on, a kernel virtual address
 503  * @bit: the bit of the word being waited on
 504  * @action: the function used to sleep, which may take special actions
 505  * @mode: the task state to sleep in
 506  *
 507  * There is a standard hashed waitqueue table for generic use. This
 508  * is the part of the hashtable's accessor API that waits on a bit
 509  * when one intends to set it, for instance, trying to lock bitflags.
 510  * For instance, if one were to have waiters trying to set bitflag
 511  * and waiting for it to clear before setting it, one would call
 512  * wait_on_bit() in threads waiting to be able to set the bit.
 513  * One uses wait_on_bit_lock() where one is waiting for the bit to
 514  * clear with the intention of setting it, and when done, clearing it.
 515  */
 516 static inline int wait_on_bit_lock(void *word, int bit,
 517                                 int (*action)(void *), unsigned mode)
 518 {
 519         if (!test_and_set_bit(bit, word))
 520                 return 0;
 521         return out_of_line_wait_on_bit_lock(word, bit, action, mode);
 522 }
 523
 524 #endif /* __KERNEL__ */
 525
 526 #endif