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 flags, void *key);
  30 int default_wake_function(wait_queue_t *wait, unsigned mode, int flags, 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, struct lock_class_key *);
  81
  82 #define init_waitqueue_head(q)                          \
  83         do {                                            \
  84                 static struct lock_class_key __key;     \
  85                                                         \
  86                 __init_waitqueue_head((q), &__key);     \
  87         } while (0)
  88
  89 #ifdef CONFIG_LOCKDEP
  90 # define __WAIT_QUEUE_HEAD_INIT_ONSTACK(name) \
  91         ({ init_waitqueue_head(&name); name; })
  92 # define DECLARE_WAIT_QUEUE_HEAD_ONSTACK(name) \
  93         wait_queue_head_t name = __WAIT_QUEUE_HEAD_INIT_ONSTACK(name)
  94 #else
  95 # define DECLARE_WAIT_QUEUE_HEAD_ONSTACK(name) DECLARE_WAIT_QUEUE_HEAD(name)
  96 #endif
  97
  98 static inline void init_waitqueue_entry(wait_queue_t *q, struct task_struct *p)
  99 {
 100         q->flags = 0;
 101         q->private = p;
 102         q->func = default_wake_function;
 103 }
 104
 105 static inline void init_waitqueue_func_entry(wait_queue_t *q,
 106                                         wait_queue_func_t func)
 107 {
 108         q->flags = 0;
 109         q->private = NULL;
 110         q->func = func;
 111 }
 112
 113 static inline int waitqueue_active(wait_queue_head_t *q)
 114 {
 115         return !list_empty(&q->task_list);
 116 }
 117
 118 extern void add_wait_queue(wait_queue_head_t *q, wait_queue_t *wait);
 119 extern void add_wait_queue_exclusive(wait_queue_head_t *q, wait_queue_t *wait);
 120 extern void remove_wait_queue(wait_queue_head_t *q, wait_queue_t *wait);
 121
 122 static inline void __add_wait_queue(wait_queue_head_t *head, wait_queue_t *new)
 123 {
 124         list_add(&new->task_list, &head->task_list);
 125 }
 126
 127 /*
 128  * Used for wake-one threads:
 129  */
 130 static inline void __add_wait_queue_tail(wait_queue_head_t *head,
 131                                                 wait_queue_t *new)
 132 {
 133         list_add_tail(&new->task_list, &head->task_list);
 134 }
 135
 136 static inline void __remove_wait_queue(wait_queue_head_t *head,
 137                                                         wait_queue_t *old)
 138 {
 139         list_del(&old->task_list);
 140 }
 141
 142 void __wake_up(wait_queue_head_t *q, unsigned int mode, int nr, void *key);
 143 void __wake_up_locked_key(wait_queue_head_t *q, unsigned int mode, void *key);
 144 void __wake_up_sync_key(wait_queue_head_t *q, unsigned int mode, int nr,
 145                         void *key);
 146 void __wake_up_locked(wait_queue_head_t *q, unsigned int mode);
 147 void __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr);
 148 void __wake_up_bit(wait_queue_head_t *, void *, int);
 149 int __wait_on_bit(wait_queue_head_t *, struct wait_bit_queue *, int (*)(void *), unsigned);
 150 int __wait_on_bit_lock(wait_queue_head_t *, struct wait_bit_queue *, int (*)(void *), unsigned);
 151 void wake_up_bit(void *, int);
 152 int out_of_line_wait_on_bit(void *, int, int (*)(void *), unsigned);
 153 int out_of_line_wait_on_bit_lock(void *, int, int (*)(void *), unsigned);
 154 wait_queue_head_t *bit_waitqueue(void *, int);
 155
 156 #define wake_up(x)                      __wake_up(x, TASK_NORMAL, 1, NULL)
 157 #define wake_up_nr(x, nr)               __wake_up(x, TASK_NORMAL, nr, NULL)
 158 #define wake_up_all(x)                  __wake_up(x, TASK_NORMAL, 0, NULL)
 159 #define wake_up_locked(x)               __wake_up_locked((x), TASK_NORMAL)
 160
 161 #define wake_up_interruptible(x)        __wake_up(x, TASK_INTERRUPTIBLE, 1, NULL)
 162 #define wake_up_interruptible_nr(x, nr) __wake_up(x, TASK_INTERRUPTIBLE, nr, NULL)
 163 #define wake_up_interruptible_all(x)    __wake_up(x, TASK_INTERRUPTIBLE, 0, NULL)
 164 #define wake_up_interruptible_sync(x)   __wake_up_sync((x), TASK_INTERRUPTIBLE, 1)
 165
 166 /*
 167  * Wakeup macros to be used to report events to the targets.
 168  */
 169 #define wake_up_poll(x, m)                              \
 170         __wake_up(x, TASK_NORMAL, 1, (void *) (m))
 171 #define wake_up_locked_poll(x, m)                               \
 172         __wake_up_locked_key((x), TASK_NORMAL, (void *) (m))
 173 #define wake_up_interruptible_poll(x, m)                        \
 174         __wake_up(x, TASK_INTERRUPTIBLE, 1, (void *) (m))
 175 #define wake_up_interruptible_sync_poll(x, m)                           \
 176         __wake_up_sync_key((x), TASK_INTERRUPTIBLE, 1, (void *) (m))
 177
 178 #define __wait_event(wq, condition)                                     \
 179 do {                                                                    \
 180         DEFINE_WAIT(__wait);                                            \
 181                                                                         \
 182         for (;;) {                                                      \
 183                 prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE);    \
 184                 if (condition)                                          \
 185                         break;                                          \
 186                 schedule();                                             \
 187         }                                                               \
 188         finish_wait(&wq, &__wait);                                      \
 189 } while (0)
 190
 191 /**
 192  * wait_event - sleep until a condition gets true
 193  * @wq: the waitqueue to wait on
 194  * @condition: a C expression for the event to wait for
 195  *
 196  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 197  * @condition evaluates to true. The @condition is checked each time
 198  * the waitqueue @wq is woken up.
 199  *
 200  * wake_up() has to be called after changing any variable that could
 201  * change the result of the wait condition.
 202  */
 203 #define wait_event(wq, condition)                                       \
 204 do {                                                                    \
 205         if (condition)                                                  \
 206                 break;                                                  \
 207         __wait_event(wq, condition);                                    \
 208 } while (0)
 209
 210 #define __wait_event_timeout(wq, condition, ret)                        \
 211 do {                                                                    \
 212         DEFINE_WAIT(__wait);                                            \
 213                                                                         \
 214         for (;;) {                                                      \
 215                 prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE);    \
 216                 if (condition)                                          \
 217                         break;                                          \
 218                 ret = schedule_timeout(ret);                            \
 219                 if (!ret)                                               \
 220                         break;                                          \
 221         }                                                               \
 222         finish_wait(&wq, &__wait);                                      \
 223 } while (0)
 224
 225 /**
 226  * wait_event_timeout - sleep until a condition gets true or a timeout elapses
 227  * @wq: the waitqueue to wait on
 228  * @condition: a C expression for the event to wait for
 229  * @timeout: timeout, in jiffies
 230  *
 231  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 232  * @condition evaluates to true. The @condition is checked each time
 233  * the waitqueue @wq is woken up.
 234  *
 235  * wake_up() has to be called after changing any variable that could
 236  * change the result of the wait condition.
 237  *
 238  * The function returns 0 if the @timeout elapsed, and the remaining
 239  * jiffies if the condition evaluated to true before the timeout elapsed.
 240  */
 241 #define wait_event_timeout(wq, condition, timeout)                      \
 242 ({                                                                      \
 243         long __ret = timeout;                                           \
 244         if (!(condition))                                               \
 245                 __wait_event_timeout(wq, condition, __ret);             \
 246         __ret;                                                          \
 247 })
 248
 249 #define __wait_event_interruptible(wq, condition, ret)                  \
 250 do {                                                                    \
 251         DEFINE_WAIT(__wait);                                            \
 252                                                                         \
 253         for (;;) {                                                      \
 254                 prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE);      \
 255                 if (condition)                                          \
 256                         break;                                          \
 257                 if (!signal_pending(current)) {                         \
 258                         schedule();                                     \
 259                         continue;                                       \
 260                 }                                                       \
 261                 ret = -ERESTARTSYS;                                     \
 262                 break;                                                  \
 263         }                                                               \
 264         finish_wait(&wq, &__wait);                                      \
 265 } while (0)
 266
 267 /**
 268  * wait_event_interruptible - sleep until a condition gets true
 269  * @wq: the waitqueue to wait on
 270  * @condition: a C expression for the event to wait for
 271  *
 272  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 273  * @condition evaluates to true or a signal is received.
 274  * The @condition is checked each time the waitqueue @wq is woken up.
 275  *
 276  * wake_up() has to be called after changing any variable that could
 277  * change the result of the wait condition.
 278  *
 279  * The function will return -ERESTARTSYS if it was interrupted by a
 280  * signal and 0 if @condition evaluated to true.
 281  */
 282 #define wait_event_interruptible(wq, condition)                         \
 283 ({                                                                      \
 284         int __ret = 0;                                                  \
 285         if (!(condition))                                               \
 286                 __wait_event_interruptible(wq, condition, __ret);       \
 287         __ret;                                                          \
 288 })
 289
 290 #define __wait_event_interruptible_timeout(wq, condition, ret)          \
 291 do {                                                                    \
 292         DEFINE_WAIT(__wait);                                            \
 293                                                                         \
 294         for (;;) {                                                      \
 295                 prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE);      \
 296                 if (condition)                                          \
 297                         break;                                          \
 298                 if (!signal_pending(current)) {                         \
 299                         ret = schedule_timeout(ret);                    \
 300                         if (!ret)                                       \
 301                                 break;                                  \
 302                         continue;                                       \
 303                 }                                                       \
 304                 ret = -ERESTARTSYS;                                     \
 305                 break;                                                  \
 306         }                                                               \
 307         finish_wait(&wq, &__wait);                                      \
 308 } while (0)
 309
 310 /**
 311  * wait_event_interruptible_timeout - sleep until a condition gets true or a timeout elapses
 312  * @wq: the waitqueue to wait on
 313  * @condition: a C expression for the event to wait for
 314  * @timeout: timeout, in jiffies
 315  *
 316  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 317  * @condition evaluates to true or a signal is received.
 318  * The @condition is checked each time the waitqueue @wq is woken up.
 319  *
 320  * wake_up() has to be called after changing any variable that could
 321  * change the result of the wait condition.
 322  *
 323  * The function returns 0 if the @timeout elapsed, -ERESTARTSYS if it
 324  * was interrupted by a signal, and the remaining jiffies otherwise
 325  * if the condition evaluated to true before the timeout elapsed.
 326  */
 327 #define wait_event_interruptible_timeout(wq, condition, timeout)        \
 328 ({                                                                      \
 329         long __ret = timeout;                                           \
 330         if (!(condition))                                               \
 331                 __wait_event_interruptible_timeout(wq, condition, __ret); \
 332         __ret;                                                          \
 333 })
 334
 335 #define __wait_event_interruptible_exclusive(wq, condition, ret)        \
 336 do {                                                                    \
 337         DEFINE_WAIT(__wait);                                            \
 338                                                                         \
 339         for (;;) {                                                      \
 340                 prepare_to_wait_exclusive(&wq, &__wait,                 \
 341                                         TASK_INTERRUPTIBLE);            \
 342                 if (condition) {                                        \
 343                         finish_wait(&wq, &__wait);                      \
 344                         break;                                          \
 345                 }                                                       \
 346                 if (!signal_pending(current)) {                         \
 347                         schedule();                                     \
 348                         continue;                                       \
 349                 }                                                       \
 350                 ret = -ERESTARTSYS;                                     \
 351                 abort_exclusive_wait(&wq, &__wait,                      \
 352                                 TASK_INTERRUPTIBLE, NULL);              \
 353                 break;                                                  \
 354         }                                                               \
 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 void abort_exclusive_wait(wait_queue_head_t *q, wait_queue_t *wait,
 444                         unsigned int mode, void *key);
 445 int autoremove_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 446 int wake_bit_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 447
 448 #define DEFINE_WAIT_FUNC(name, function)                                \
 449         wait_queue_t name = {                                           \
 450                 .private        = current,                              \
 451                 .func           = function,                             \
 452                 .task_list      = LIST_HEAD_INIT((name).task_list),     \
 453         }
 454
 455 #define DEFINE_WAIT(name) DEFINE_WAIT_FUNC(name, autoremove_wake_function)
 456
 457 #define DEFINE_WAIT_BIT(name, word, bit)                                \
 458         struct wait_bit_queue name = {                                  \
 459                 .key = __WAIT_BIT_KEY_INITIALIZER(word, bit),           \
 460                 .wait   = {                                             \
 461                         .private        = current,                      \
 462                         .func           = wake_bit_function,            \
 463                         .task_list      =                               \
 464                                 LIST_HEAD_INIT((name).wait.task_list),  \
 465                 },                                                      \
 466         }
 467
 468 #define init_wait(wait)                                                 \
 469         do {                                                            \
 470                 (wait)->private = current;                              \
 471                 (wait)->func = autoremove_wake_function;                \
 472                 INIT_LIST_HEAD(&(wait)->task_list);                     \
 473         } while (0)
 474
 475 /**
 476  * wait_on_bit - wait for a bit to be cleared
 477  * @word: the word being waited on, a kernel virtual address
 478  * @bit: the bit of the word being waited on
 479  * @action: the function used to sleep, which may take special actions
 480  * @mode: the task state to sleep in
 481  *
 482  * There is a standard hashed waitqueue table for generic use. This
 483  * is the part of the hashtable's accessor API that waits on a bit.
 484  * For instance, if one were to have waiters on a bitflag, one would
 485  * call wait_on_bit() in threads waiting for the bit to clear.
 486  * One uses wait_on_bit() where one is waiting for the bit to clear,
 487  * but has no intention of setting it.
 488  */
 489 static inline int wait_on_bit(void *word, int bit,
 490                                 int (*action)(void *), unsigned mode)
 491 {
 492         if (!test_bit(bit, word))
 493                 return 0;
 494         return out_of_line_wait_on_bit(word, bit, action, mode);
 495 }
 496
 497 /**
 498  * wait_on_bit_lock - wait for a bit to be cleared, when wanting to set it
 499  * @word: the word being waited on, a kernel virtual address
 500  * @bit: the bit of the word being waited on
 501  * @action: the function used to sleep, which may take special actions
 502  * @mode: the task state to sleep in
 503  *
 504  * There is a standard hashed waitqueue table for generic use. This
 505  * is the part of the hashtable's accessor API that waits on a bit
 506  * when one intends to set it, for instance, trying to lock bitflags.
 507  * For instance, if one were to have waiters trying to set bitflag
 508  * and waiting for it to clear before setting it, one would call
 509  * wait_on_bit() in threads waiting to be able to set the bit.
 510  * One uses wait_on_bit_lock() where one is waiting for the bit to
 511  * clear with the intention of setting it, and when done, clearing it.
 512  */
 513 static inline int wait_on_bit_lock(void *word, int bit,
 514                                 int (*action)(void *), unsigned mode)
 515 {
 516         if (!test_and_set_bit(bit, word))
 517                 return 0;
 518         return out_of_line_wait_on_bit_lock(word, bit, action, mode);
 519 }
 520
 521 #endif /* __KERNEL__ */
 522
 523 #endif