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