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