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