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