include/linux/wait.h

   1 #ifndef _LINUX_WAIT_H
   2 #define _LINUX_WAIT_H
   3
   4 #define WNOHANG         0x00000001
   5 #define WUNTRACED       0x00000002
   6 #define WSTOPPED        WUNTRACED
   7 #define WEXITED         0x00000004
   8 #define WCONTINUED      0x00000008
   9 #define WNOWAIT         0x01000000      /* Don't reap, just poll status.  */
  10
  11 #define __WNOTHREAD     0x20000000      /* Don't wait on children of other threads in this group */
  12 #define __WALL          0x40000000      /* Wait on all children, regardless of type */
  13 #define __WCLONE        0x80000000      /* Wait only on non-SIGCHLD children */
  14
  15 /* First argument to waitid: */
  16 #define P_ALL           0
  17 #define P_PID           1
  18 #define P_PGID          2
  19
  20 #ifdef __KERNEL__
  21
  22 #include <linux/list.h>
  23 #include <linux/stddef.h>
  24 #include <linux/spinlock.h>
  25 #include <asm/system.h>
  26 #include <asm/current.h>
  27
  28 typedef struct __wait_queue wait_queue_t;
  29 typedef int (*wait_queue_func_t)(wait_queue_t *wait, unsigned mode, int sync, void *key);
  30 int default_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
  31
  32 struct __wait_queue {
  33         unsigned int flags;
  34 #define WQ_FLAG_EXCLUSIVE       0x01
  35         void *private;
  36         wait_queue_func_t func;
  37         struct list_head task_list;
  38 };
  39
  40 struct wait_bit_key {
  41         void *flags;
  42         int bit_nr;
  43 };
  44
  45 struct wait_bit_queue {
  46         struct wait_bit_key key;
  47         wait_queue_t wait;
  48 };
  49
  50 struct __wait_queue_head {
  51         spinlock_t lock;
  52         struct list_head task_list;
  53 };
  54 typedef struct __wait_queue_head wait_queue_head_t;
  55
  56 struct task_struct;
  57
  58 /*
  59  * Macros for declaration and initialisaton of the datatypes
  60  */
  61
  62 #define __WAITQUEUE_INITIALIZER(name, tsk) {                            \
  63         .private        = tsk,                                          \
  64         .func           = default_wake_function,                        \
  65         .task_list      = { NULL, NULL } }
  66
  67 #define DECLARE_WAITQUEUE(name, tsk)                                    \
  68         wait_queue_t name = __WAITQUEUE_INITIALIZER(name, tsk)
  69
  70 #define __WAIT_QUEUE_HEAD_INITIALIZER(name) {                           \
  71         .lock           = __SPIN_LOCK_UNLOCKED(name.lock),              \
  72         .task_list      = { &(name).task_list, &(name).task_list } }
  73
  74 #define DECLARE_WAIT_QUEUE_HEAD(name) \
  75         wait_queue_head_t name = __WAIT_QUEUE_HEAD_INITIALIZER(name)
  76
  77 #define __WAIT_BIT_KEY_INITIALIZER(word, bit)                           \
  78         { .flags = word, .bit_nr = bit, }
  79
  80 extern void init_waitqueue_head(wait_queue_head_t *q);
  81
  82 #ifdef CONFIG_LOCKDEP
  83 # define __WAIT_QUEUE_HEAD_INIT_ONSTACK(name) \
  84         ({ init_waitqueue_head(&name); name; })
  85 # define DECLARE_WAIT_QUEUE_HEAD_ONSTACK(name) \
  86         wait_queue_head_t name = __WAIT_QUEUE_HEAD_INIT_ONSTACK(name)
  87 #else
  88 # define DECLARE_WAIT_QUEUE_HEAD_ONSTACK(name) DECLARE_WAIT_QUEUE_HEAD(name)
  89 #endif
  90
  91 static inline void init_waitqueue_entry(wait_queue_t *q, struct task_struct *p)
  92 {
  93         q->flags = 0;
  94         q->private = p;
  95         q->func = default_wake_function;
  96 }
  97
  98 static inline void init_waitqueue_func_entry(wait_queue_t *q,
  99                                         wait_queue_func_t func)
 100 {
 101         q->flags = 0;
 102         q->private = NULL;
 103         q->func = func;
 104 }
 105
 106 static inline int waitqueue_active(wait_queue_head_t *q)
 107 {
 108         return !list_empty(&q->task_list);
 109 }
 110
 111 /*
 112  * Used to distinguish between sync and async io wait context:
 113  * sync i/o typically specifies a NULL wait queue entry or a wait
 114  * queue entry bound to a task (current task) to wake up.
 115  * aio specifies a wait queue entry with an async notification
 116  * callback routine, not associated with any task.
 117  */
 118 #define is_sync_wait(wait)      (!(wait) || ((wait)->private))
 119
 120 extern void FASTCALL(add_wait_queue(wait_queue_head_t *q, wait_queue_t * wait));
 121 extern void FASTCALL(add_wait_queue_exclusive(wait_queue_head_t *q, wait_queue_t * wait));
 122 extern void FASTCALL(remove_wait_queue(wait_queue_head_t *q, wait_queue_t * wait));
 123
 124 static inline void __add_wait_queue(wait_queue_head_t *head, wait_queue_t *new)
 125 {
 126         list_add(&new->task_list, &head->task_list);
 127 }
 128
 129 /*
 130  * Used for wake-one threads:
 131  */
 132 static inline void __add_wait_queue_tail(wait_queue_head_t *head,
 133                                                 wait_queue_t *new)
 134 {
 135         list_add_tail(&new->task_list, &head->task_list);
 136 }
 137
 138 static inline void __remove_wait_queue(wait_queue_head_t *head,
 139                                                         wait_queue_t *old)
 140 {
 141         list_del(&old->task_list);
 142 }
 143
 144 void FASTCALL(__wake_up(wait_queue_head_t *q, unsigned int mode, int nr, void *key));
 145 extern void FASTCALL(__wake_up_locked(wait_queue_head_t *q, unsigned int mode));
 146 extern void FASTCALL(__wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr));
 147 void FASTCALL(__wake_up_bit(wait_queue_head_t *, void *, int));
 148 int FASTCALL(__wait_on_bit(wait_queue_head_t *, struct wait_bit_queue *, int (*)(void *), unsigned));
 149 int FASTCALL(__wait_on_bit_lock(wait_queue_head_t *, struct wait_bit_queue *, int (*)(void *), unsigned));
 150 void FASTCALL(wake_up_bit(void *, int));
 151 int FASTCALL(out_of_line_wait_on_bit(void *, int, int (*)(void *), unsigned));
 152 int FASTCALL(out_of_line_wait_on_bit_lock(void *, int, int (*)(void *), unsigned));
 153 wait_queue_head_t *FASTCALL(bit_waitqueue(void *, int));
 154
 155 #define wake_up(x)                      __wake_up(x, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE, 1, NULL)
 156 #define wake_up_nr(x, nr)               __wake_up(x, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE, nr, NULL)
 157 #define wake_up_all(x)                  __wake_up(x, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE, 0, NULL)
 158 #define wake_up_interruptible(x)        __wake_up(x, TASK_INTERRUPTIBLE, 1, NULL)
 159 #define wake_up_interruptible_nr(x, nr) __wake_up(x, TASK_INTERRUPTIBLE, nr, NULL)
 160 #define wake_up_interruptible_all(x)    __wake_up(x, TASK_INTERRUPTIBLE, 0, NULL)
 161 #define wake_up_locked(x)               __wake_up_locked((x), TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE)
 162 #define wake_up_interruptible_sync(x)   __wake_up_sync((x),TASK_INTERRUPTIBLE, 1)
 163
 164 #define __wait_event(wq, condition)                                     \
 165 do {                                                                    \
 166         DEFINE_WAIT(__wait);                                            \
 167                                                                         \
 168         for (;;) {                                                      \
 169                 prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE);    \
 170                 if (condition)                                          \
 171                         break;                                          \
 172                 schedule();                                             \
 173         }                                                               \
 174         finish_wait(&wq, &__wait);                                      \
 175 } while (0)
 176
 177 /**
 178  * wait_event - sleep until a condition gets true
 179  * @wq: the waitqueue to wait on
 180  * @condition: a C expression for the event to wait for
 181  *
 182  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 183  * @condition evaluates to true. The @condition is checked each time
 184  * the waitqueue @wq is woken up.
 185  *
 186  * wake_up() has to be called after changing any variable that could
 187  * change the result of the wait condition.
 188  */
 189 #define wait_event(wq, condition)                                       \
 190 do {                                                                    \
 191         if (condition)                                                  \
 192                 break;                                                  \
 193         __wait_event(wq, condition);                                    \
 194 } while (0)
 195
 196 #define __wait_event_timeout(wq, condition, ret)                        \
 197 do {                                                                    \
 198         DEFINE_WAIT(__wait);                                            \
 199                                                                         \
 200         for (;;) {                                                      \
 201                 prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE);    \
 202                 if (condition)                                          \
 203                         break;                                          \
 204                 ret = schedule_timeout(ret);                            \
 205                 if (!ret)                                               \
 206                         break;                                          \
 207         }                                                               \
 208         finish_wait(&wq, &__wait);                                      \
 209 } while (0)
 210
 211 /**
 212  * wait_event_timeout - sleep until a condition gets true or a timeout elapses
 213  * @wq: the waitqueue to wait on
 214  * @condition: a C expression for the event to wait for
 215  * @timeout: timeout, in jiffies
 216  *
 217  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 218  * @condition evaluates to true. The @condition is checked each time
 219  * the waitqueue @wq is woken up.
 220  *
 221  * wake_up() has to be called after changing any variable that could
 222  * change the result of the wait condition.
 223  *
 224  * The function returns 0 if the @timeout elapsed, and the remaining
 225  * jiffies if the condition evaluated to true before the timeout elapsed.
 226  */
 227 #define wait_event_timeout(wq, condition, timeout)                      \
 228 ({                                                                      \
 229         long __ret = timeout;                                           \
 230         if (!(condition))                                               \
 231                 __wait_event_timeout(wq, condition, __ret);             \
 232         __ret;                                                          \
 233 })
 234
 235 #define __wait_event_interruptible(wq, condition, ret)                  \
 236 do {                                                                    \
 237         DEFINE_WAIT(__wait);                                            \
 238                                                                         \
 239         for (;;) {                                                      \
 240                 prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE);      \
 241                 if (condition)                                          \
 242                         break;                                          \
 243                 if (!signal_pending(current)) {                         \
 244                         schedule();                                     \
 245                         continue;                                       \
 246                 }                                                       \
 247                 ret = -ERESTARTSYS;                                     \
 248                 break;                                                  \
 249         }                                                               \
 250         finish_wait(&wq, &__wait);                                      \
 251 } while (0)
 252
 253 /**
 254  * wait_event_interruptible - sleep until a condition gets true
 255  * @wq: the waitqueue to wait on
 256  * @condition: a C expression for the event to wait for
 257  *
 258  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 259  * @condition evaluates to true or a signal is received.
 260  * The @condition is checked each time the waitqueue @wq is woken up.
 261  *
 262  * wake_up() has to be called after changing any variable that could
 263  * change the result of the wait condition.
 264  *
 265  * The function will return -ERESTARTSYS if it was interrupted by a
 266  * signal and 0 if @condition evaluated to true.
 267  */
 268 #define wait_event_interruptible(wq, condition)                         \
 269 ({                                                                      \
 270         int __ret = 0;                                                  \
 271         if (!(condition))                                               \
 272                 __wait_event_interruptible(wq, condition, __ret);       \
 273         __ret;                                                          \
 274 })
 275
 276 #define __wait_event_interruptible_timeout(wq, condition, ret)          \
 277 do {                                                                    \
 278         DEFINE_WAIT(__wait);                                            \
 279                                                                         \
 280         for (;;) {                                                      \
 281                 prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE);      \
 282                 if (condition)                                          \
 283                         break;                                          \
 284                 if (!signal_pending(current)) {                         \
 285                         ret = schedule_timeout(ret);                    \
 286                         if (!ret)                                       \
 287                                 break;                                  \
 288                         continue;                                       \
 289                 }                                                       \
 290                 ret = -ERESTARTSYS;                                     \
 291                 break;                                                  \
 292         }                                                               \
 293         finish_wait(&wq, &__wait);                                      \
 294 } while (0)
 295
 296 /**
 297  * wait_event_interruptible_timeout - sleep until a condition gets true or a timeout elapses
 298  * @wq: the waitqueue to wait on
 299  * @condition: a C expression for the event to wait for
 300  * @timeout: timeout, in jiffies
 301  *
 302  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 303  * @condition evaluates to true or a signal is received.
 304  * The @condition is checked each time the waitqueue @wq is woken up.
 305  *
 306  * wake_up() has to be called after changing any variable that could
 307  * change the result of the wait condition.
 308  *
 309  * The function returns 0 if the @timeout elapsed, -ERESTARTSYS if it
 310  * was interrupted by a signal, and the remaining jiffies otherwise
 311  * if the condition evaluated to true before the timeout elapsed.
 312  */
 313 #define wait_event_interruptible_timeout(wq, condition, timeout)        \
 314 ({                                                                      \
 315         long __ret = timeout;                                           \
 316         if (!(condition))                                               \
 317                 __wait_event_interruptible_timeout(wq, condition, __ret); \
 318         __ret;                                                          \
 319 })
 320
 321 #define __wait_event_interruptible_exclusive(wq, condition, ret)        \
 322 do {                                                                    \
 323         DEFINE_WAIT(__wait);                                            \
 324                                                                         \
 325         for (;;) {                                                      \
 326                 prepare_to_wait_exclusive(&wq, &__wait,                 \
 327                                         TASK_INTERRUPTIBLE);            \
 328                 if (condition)                                          \
 329                         break;                                          \
 330                 if (!signal_pending(current)) {                         \
 331                         schedule();                                     \
 332                         continue;                                       \
 333                 }                                                       \
 334                 ret = -ERESTARTSYS;                                     \
 335                 break;                                                  \
 336         }                                                               \
 337         finish_wait(&wq, &__wait);                                      \
 338 } while (0)
 339
 340 #define wait_event_interruptible_exclusive(wq, condition)               \
 341 ({                                                                      \
 342         int __ret = 0;                                                  \
 343         if (!(condition))                                               \
 344                 __wait_event_interruptible_exclusive(wq, condition, __ret);\
 345         __ret;                                                          \
 346 })
 347
 348 /*
 349  * Must be called with the spinlock in the wait_queue_head_t held.
 350  */
 351 static inline void add_wait_queue_exclusive_locked(wait_queue_head_t *q,
 352                                                    wait_queue_t * wait)
 353 {
 354         wait->flags |= WQ_FLAG_EXCLUSIVE;
 355         __add_wait_queue_tail(q,  wait);
 356 }
 357
 358 /*
 359  * Must be called with the spinlock in the wait_queue_head_t held.
 360  */
 361 static inline void remove_wait_queue_locked(wait_queue_head_t *q,
 362                                             wait_queue_t * wait)
 363 {
 364         __remove_wait_queue(q,  wait);
 365 }
 366
 367 /*
 368  * These are the old interfaces to sleep waiting for an event.
 369  * They are racy.  DO NOT use them, use the wait_event* interfaces above.
 370  * We plan to remove these interfaces.
 371  */
 372 extern void sleep_on(wait_queue_head_t *q);
 373 extern long sleep_on_timeout(wait_queue_head_t *q,
 374                                       signed long timeout);
 375 extern void interruptible_sleep_on(wait_queue_head_t *q);
 376 extern long interruptible_sleep_on_timeout(wait_queue_head_t *q,
 377                                            signed long timeout);
 378
 379 /*
 380  * Waitqueues which are removed from the waitqueue_head at wakeup time
 381  */
 382 void FASTCALL(prepare_to_wait(wait_queue_head_t *q,
 383                                 wait_queue_t *wait, int state));
 384 void FASTCALL(prepare_to_wait_exclusive(wait_queue_head_t *q,
 385                                 wait_queue_t *wait, int state));
 386 void FASTCALL(finish_wait(wait_queue_head_t *q, wait_queue_t *wait));
 387 int autoremove_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 388 int wake_bit_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 389
 390 #define DEFINE_WAIT(name)                                               \
 391         wait_queue_t name = {                                           \
 392                 .private        = current,                              \
 393                 .func           = autoremove_wake_function,             \
 394                 .task_list      = LIST_HEAD_INIT((name).task_list),     \
 395         }
 396
 397 #define DEFINE_WAIT_BIT(name, word, bit)                                \
 398         struct wait_bit_queue name = {                                  \
 399                 .key = __WAIT_BIT_KEY_INITIALIZER(word, bit),           \
 400                 .wait   = {                                             \
 401                         .private        = current,                      \
 402                         .func           = wake_bit_function,            \
 403                         .task_list      =                               \
 404                                 LIST_HEAD_INIT((name).wait.task_list),  \
 405                 },                                                      \
 406         }
 407
 408 #define init_wait(wait)                                                 \
 409         do {                                                            \
 410                 (wait)->private = current;                              \
 411                 (wait)->func = autoremove_wake_function;                \
 412                 INIT_LIST_HEAD(&(wait)->task_list);                     \
 413         } while (0)
 414
 415 /**
 416  * wait_on_bit - wait for a bit to be cleared
 417  * @word: the word being waited on, a kernel virtual address
 418  * @bit: the bit of the word being waited on
 419  * @action: the function used to sleep, which may take special actions
 420  * @mode: the task state to sleep in
 421  *
 422  * There is a standard hashed waitqueue table for generic use. This
 423  * is the part of the hashtable's accessor API that waits on a bit.
 424  * For instance, if one were to have waiters on a bitflag, one would
 425  * call wait_on_bit() in threads waiting for the bit to clear.
 426  * One uses wait_on_bit() where one is waiting for the bit to clear,
 427  * but has no intention of setting it.
 428  */
 429 static inline int wait_on_bit(void *word, int bit,
 430                                 int (*action)(void *), unsigned mode)
 431 {
 432         if (!test_bit(bit, word))
 433                 return 0;
 434         return out_of_line_wait_on_bit(word, bit, action, mode);
 435 }
 436
 437 /**
 438  * wait_on_bit_lock - wait for a bit to be cleared, when wanting to set it
 439  * @word: the word being waited on, a kernel virtual address
 440  * @bit: the bit of the word being waited on
 441  * @action: the function used to sleep, which may take special actions
 442  * @mode: the task state to sleep in
 443  *
 444  * There is a standard hashed waitqueue table for generic use. This
 445  * is the part of the hashtable's accessor API that waits on a bit
 446  * when one intends to set it, for instance, trying to lock bitflags.
 447  * For instance, if one were to have waiters trying to set bitflag
 448  * and waiting for it to clear before setting it, one would call
 449  * wait_on_bit() in threads waiting to be able to set the bit.
 450  * One uses wait_on_bit_lock() where one is waiting for the bit to
 451  * clear with the intention of setting it, and when done, clearing it.
 452  */
 453 static inline int wait_on_bit_lock(void *word, int bit,
 454                                 int (*action)(void *), unsigned mode)
 455 {
 456         if (!test_and_set_bit(bit, word))
 457                 return 0;
 458         return out_of_line_wait_on_bit_lock(word, bit, action, mode);
 459 }
 460
 461 #endif /* __KERNEL__ */
 462
 463 #endif