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