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 /*
  81  * lockdep: we want one lock-class for all waitqueue locks.
  82  */
  83 extern struct lock_class_key waitqueue_lock_key;
  84
  85 static inline void init_waitqueue_head(wait_queue_head_t *q)
  86 {
  87         spin_lock_init(&q->lock);
  88         lockdep_set_class(&q->lock, &waitqueue_lock_key);
  89         INIT_LIST_HEAD(&q->task_list);
  90 }
  91
  92 static inline void init_waitqueue_entry(wait_queue_t *q, struct task_struct *p)
  93 {
  94         q->flags = 0;
  95         q->private = p;
  96         q->func = default_wake_function;
  97 }
  98
  99 static inline void init_waitqueue_func_entry(wait_queue_t *q,
 100                                         wait_queue_func_t func)
 101 {
 102         q->flags = 0;
 103         q->private = NULL;
 104         q->func = func;
 105 }
 106
 107 static inline int waitqueue_active(wait_queue_head_t *q)
 108 {
 109         return !list_empty(&q->task_list);
 110 }
 111
 112 /*
 113  * Used to distinguish between sync and async io wait context:
 114  * sync i/o typically specifies a NULL wait queue entry or a wait
 115  * queue entry bound to a task (current task) to wake up.
 116  * aio specifies a wait queue entry with an async notification
 117  * callback routine, not associated with any task.
 118  */
 119 #define is_sync_wait(wait)      (!(wait) || ((wait)->private))
 120
 121 extern void FASTCALL(add_wait_queue(wait_queue_head_t *q, wait_queue_t * wait));
 122 extern void FASTCALL(add_wait_queue_exclusive(wait_queue_head_t *q, wait_queue_t * wait));
 123 extern void FASTCALL(remove_wait_queue(wait_queue_head_t *q, wait_queue_t * wait));
 124
 125 static inline void __add_wait_queue(wait_queue_head_t *head, wait_queue_t *new)
 126 {
 127         list_add(&new->task_list, &head->task_list);
 128 }
 129
 130 /*
 131  * Used for wake-one threads:
 132  */
 133 static inline void __add_wait_queue_tail(wait_queue_head_t *head,
 134                                                 wait_queue_t *new)
 135 {
 136         list_add_tail(&new->task_list, &head->task_list);
 137 }
 138
 139 static inline void __remove_wait_queue(wait_queue_head_t *head,
 140                                                         wait_queue_t *old)
 141 {
 142         list_del(&old->task_list);
 143 }
 144
 145 void FASTCALL(__wake_up(wait_queue_head_t *q, unsigned int mode, int nr, void *key));
 146 extern void FASTCALL(__wake_up_locked(wait_queue_head_t *q, unsigned int mode));
 147 extern void FASTCALL(__wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr));
 148 void FASTCALL(__wake_up_bit(wait_queue_head_t *, void *, int));
 149 int FASTCALL(__wait_on_bit(wait_queue_head_t *, struct wait_bit_queue *, int (*)(void *), unsigned));
 150 int FASTCALL(__wait_on_bit_lock(wait_queue_head_t *, struct wait_bit_queue *, int (*)(void *), unsigned));
 151 void FASTCALL(wake_up_bit(void *, int));
 152 int FASTCALL(out_of_line_wait_on_bit(void *, int, int (*)(void *), unsigned));
 153 int FASTCALL(out_of_line_wait_on_bit_lock(void *, int, int (*)(void *), unsigned));
 154 wait_queue_head_t *FASTCALL(bit_waitqueue(void *, int));
 155
 156 #define wake_up(x)                      __wake_up(x, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE, 1, NULL)
 157 #define wake_up_nr(x, nr)               __wake_up(x, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE, nr, NULL)
 158 #define wake_up_all(x)                  __wake_up(x, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE, 0, NULL)
 159 #define wake_up_interruptible(x)        __wake_up(x, TASK_INTERRUPTIBLE, 1, NULL)
 160 #define wake_up_interruptible_nr(x, nr) __wake_up(x, TASK_INTERRUPTIBLE, nr, NULL)
 161 #define wake_up_interruptible_all(x)    __wake_up(x, TASK_INTERRUPTIBLE, 0, NULL)
 162 #define wake_up_locked(x)               __wake_up_locked((x), TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE)
 163 #define wake_up_interruptible_sync(x)   __wake_up_sync((x),TASK_INTERRUPTIBLE, 1)
 164
 165 #define __wait_event(wq, condition)                                     \
 166 do {                                                                    \
 167         DEFINE_WAIT(__wait);                                            \
 168                                                                         \
 169         for (;;) {                                                      \
 170                 prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE);    \
 171                 if (condition)                                          \
 172                         break;                                          \
 173                 schedule();                                             \
 174         }                                                               \
 175         finish_wait(&wq, &__wait);                                      \
 176 } while (0)
 177
 178 /**
 179  * wait_event - sleep until a condition gets true
 180  * @wq: the waitqueue to wait on
 181  * @condition: a C expression for the event to wait for
 182  *
 183  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 184  * @condition evaluates to true. The @condition is checked each time
 185  * the waitqueue @wq is woken up.
 186  *
 187  * wake_up() has to be called after changing any variable that could
 188  * change the result of the wait condition.
 189  */
 190 #define wait_event(wq, condition)                                       \
 191 do {                                                                    \
 192         if (condition)                                                  \
 193                 break;                                                  \
 194         __wait_event(wq, condition);                                    \
 195 } while (0)
 196
 197 #define __wait_event_timeout(wq, condition, ret)                        \
 198 do {                                                                    \
 199         DEFINE_WAIT(__wait);                                            \
 200                                                                         \
 201         for (;;) {                                                      \
 202                 prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE);    \
 203                 if (condition)                                          \
 204                         break;                                          \
 205                 ret = schedule_timeout(ret);                            \
 206                 if (!ret)                                               \
 207                         break;                                          \
 208         }                                                               \
 209         finish_wait(&wq, &__wait);                                      \
 210 } while (0)
 211
 212 /**
 213  * wait_event_timeout - sleep until a condition gets true or a timeout elapses
 214  * @wq: the waitqueue to wait on
 215  * @condition: a C expression for the event to wait for
 216  * @timeout: timeout, in jiffies
 217  *
 218  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 219  * @condition evaluates to true. The @condition is checked each time
 220  * the waitqueue @wq is woken up.
 221  *
 222  * wake_up() has to be called after changing any variable that could
 223  * change the result of the wait condition.
 224  *
 225  * The function returns 0 if the @timeout elapsed, and the remaining
 226  * jiffies if the condition evaluated to true before the timeout elapsed.
 227  */
 228 #define wait_event_timeout(wq, condition, timeout)                      \
 229 ({                                                                      \
 230         long __ret = timeout;                                           \
 231         if (!(condition))                                               \
 232                 __wait_event_timeout(wq, condition, __ret);             \
 233         __ret;                                                          \
 234 })
 235
 236 #define __wait_event_interruptible(wq, condition, ret)                  \
 237 do {                                                                    \
 238         DEFINE_WAIT(__wait);                                            \
 239                                                                         \
 240         for (;;) {                                                      \
 241                 prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE);      \
 242                 if (condition)                                          \
 243                         break;                                          \
 244                 if (!signal_pending(current)) {                         \
 245                         schedule();                                     \
 246                         continue;                                       \
 247                 }                                                       \
 248                 ret = -ERESTARTSYS;                                     \
 249                 break;                                                  \
 250         }                                                               \
 251         finish_wait(&wq, &__wait);                                      \
 252 } while (0)
 253
 254 /**
 255  * wait_event_interruptible - sleep until a condition gets true
 256  * @wq: the waitqueue to wait on
 257  * @condition: a C expression for the event to wait for
 258  *
 259  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 260  * @condition evaluates to true or a signal is received.
 261  * The @condition is checked each time the waitqueue @wq is woken up.
 262  *
 263  * wake_up() has to be called after changing any variable that could
 264  * change the result of the wait condition.
 265  *
 266  * The function will return -ERESTARTSYS if it was interrupted by a
 267  * signal and 0 if @condition evaluated to true.
 268  */
 269 #define wait_event_interruptible(wq, condition)                         \
 270 ({                                                                      \
 271         int __ret = 0;                                                  \
 272         if (!(condition))                                               \
 273                 __wait_event_interruptible(wq, condition, __ret);       \
 274         __ret;                                                          \
 275 })
 276
 277 #define __wait_event_interruptible_timeout(wq, condition, ret)          \
 278 do {                                                                    \
 279         DEFINE_WAIT(__wait);                                            \
 280                                                                         \
 281         for (;;) {                                                      \
 282                 prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE);      \
 283                 if (condition)                                          \
 284                         break;                                          \
 285                 if (!signal_pending(current)) {                         \
 286                         ret = schedule_timeout(ret);                    \
 287                         if (!ret)                                       \
 288                                 break;                                  \
 289                         continue;                                       \
 290                 }                                                       \
 291                 ret = -ERESTARTSYS;                                     \
 292                 break;                                                  \
 293         }                                                               \
 294         finish_wait(&wq, &__wait);                                      \
 295 } while (0)
 296
 297 /**
 298  * wait_event_interruptible_timeout - sleep until a condition gets true or a timeout elapses
 299  * @wq: the waitqueue to wait on
 300  * @condition: a C expression for the event to wait for
 301  * @timeout: timeout, in jiffies
 302  *
 303  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 304  * @condition evaluates to true or a signal is received.
 305  * The @condition is checked each time the waitqueue @wq is woken up.
 306  *
 307  * wake_up() has to be called after changing any variable that could
 308  * change the result of the wait condition.
 309  *
 310  * The function returns 0 if the @timeout elapsed, -ERESTARTSYS if it
 311  * was interrupted by a signal, and the remaining jiffies otherwise
 312  * if the condition evaluated to true before the timeout elapsed.
 313  */
 314 #define wait_event_interruptible_timeout(wq, condition, timeout)        \
 315 ({                                                                      \
 316         long __ret = timeout;                                           \
 317         if (!(condition))                                               \
 318                 __wait_event_interruptible_timeout(wq, condition, __ret); \
 319         __ret;                                                          \
 320 })
 321
 322 #define __wait_event_interruptible_exclusive(wq, condition, ret)        \
 323 do {                                                                    \
 324         DEFINE_WAIT(__wait);                                            \
 325                                                                         \
 326         for (;;) {                                                      \
 327                 prepare_to_wait_exclusive(&wq, &__wait,                 \
 328                                         TASK_INTERRUPTIBLE);            \
 329                 if (condition)                                          \
 330                         break;                                          \
 331                 if (!signal_pending(current)) {                         \
 332                         schedule();                                     \
 333                         continue;                                       \
 334                 }                                                       \
 335                 ret = -ERESTARTSYS;                                     \
 336                 break;                                                  \
 337         }                                                               \
 338         finish_wait(&wq, &__wait);                                      \
 339 } while (0)
 340
 341 #define wait_event_interruptible_exclusive(wq, condition)               \
 342 ({                                                                      \
 343         int __ret = 0;                                                  \
 344         if (!(condition))                                               \
 345                 __wait_event_interruptible_exclusive(wq, condition, __ret);\
 346         __ret;                                                          \
 347 })
 348
 349 /*
 350  * Must be called with the spinlock in the wait_queue_head_t held.
 351  */
 352 static inline void add_wait_queue_exclusive_locked(wait_queue_head_t *q,
 353                                                    wait_queue_t * wait)
 354 {
 355         wait->flags |= WQ_FLAG_EXCLUSIVE;
 356         __add_wait_queue_tail(q,  wait);
 357 }
 358
 359 /*
 360  * Must be called with the spinlock in the wait_queue_head_t held.
 361  */
 362 static inline void remove_wait_queue_locked(wait_queue_head_t *q,
 363                                             wait_queue_t * wait)
 364 {
 365         __remove_wait_queue(q,  wait);
 366 }
 367
 368 /*
 369  * These are the old interfaces to sleep waiting for an event.
 370  * They are racy.  DO NOT use them, use the wait_event* interfaces above.
 371  * We plan to remove these interfaces during 2.7.
 372  */
 373 extern void FASTCALL(sleep_on(wait_queue_head_t *q));
 374 extern long FASTCALL(sleep_on_timeout(wait_queue_head_t *q,
 375                                       signed long timeout));
 376 extern void FASTCALL(interruptible_sleep_on(wait_queue_head_t *q));
 377 extern long FASTCALL(interruptible_sleep_on_timeout(wait_queue_head_t *q,
 378                                                     signed long timeout));
 379
 380 /*
 381  * Waitqueues which are removed from the waitqueue_head at wakeup time
 382  */
 383 void FASTCALL(prepare_to_wait(wait_queue_head_t *q,
 384                                 wait_queue_t *wait, int state));
 385 void FASTCALL(prepare_to_wait_exclusive(wait_queue_head_t *q,
 386                                 wait_queue_t *wait, int state));
 387 void FASTCALL(finish_wait(wait_queue_head_t *q, wait_queue_t *wait));
 388 int autoremove_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 389 int wake_bit_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 390
 391 #define DEFINE_WAIT(name)                                               \
 392         wait_queue_t name = {                                           \
 393                 .private        = current,                              \
 394                 .func           = autoremove_wake_function,             \
 395                 .task_list      = LIST_HEAD_INIT((name).task_list),     \
 396         }
 397
 398 #define DEFINE_WAIT_BIT(name, word, bit)                                \
 399         struct wait_bit_queue name = {                                  \
 400                 .key = __WAIT_BIT_KEY_INITIALIZER(word, bit),           \
 401                 .wait   = {                                             \
 402                         .private        = current,                      \
 403                         .func           = wake_bit_function,            \
 404                         .task_list      =                               \
 405                                 LIST_HEAD_INIT((name).wait.task_list),  \
 406                 },                                                      \
 407         }
 408
 409 #define init_wait(wait)                                                 \
 410         do {                                                            \
 411                 (wait)->private = current;                              \
 412                 (wait)->func = autoremove_wake_function;                \
 413                 INIT_LIST_HEAD(&(wait)->task_list);                     \
 414         } while (0)
 415
 416 /**
 417  * wait_on_bit - wait for a bit to be cleared
 418  * @word: the word being waited on, a kernel virtual address
 419  * @bit: the bit of the word being waited on
 420  * @action: the function used to sleep, which may take special actions
 421  * @mode: the task state to sleep in
 422  *
 423  * There is a standard hashed waitqueue table for generic use. This
 424  * is the part of the hashtable's accessor API that waits on a bit.
 425  * For instance, if one were to have waiters on a bitflag, one would
 426  * call wait_on_bit() in threads waiting for the bit to clear.
 427  * One uses wait_on_bit() where one is waiting for the bit to clear,
 428  * but has no intention of setting it.
 429  */
 430 static inline int wait_on_bit(void *word, int bit,
 431                                 int (*action)(void *), unsigned mode)
 432 {
 433         if (!test_bit(bit, word))
 434                 return 0;
 435         return out_of_line_wait_on_bit(word, bit, action, mode);
 436 }
 437
 438 /**
 439  * wait_on_bit_lock - wait for a bit to be cleared, when wanting to set it
 440  * @word: the word being waited on, a kernel virtual address
 441  * @bit: the bit of the word being waited on
 442  * @action: the function used to sleep, which may take special actions
 443  * @mode: the task state to sleep in
 444  *
 445  * There is a standard hashed waitqueue table for generic use. This
 446  * is the part of the hashtable's accessor API that waits on a bit
 447  * when one intends to set it, for instance, trying to lock bitflags.
 448  * For instance, if one were to have waiters trying to set bitflag
 449  * and waiting for it to clear before setting it, one would call
 450  * wait_on_bit() in threads waiting to be able to set the bit.
 451  * One uses wait_on_bit_lock() where one is waiting for the bit to
 452  * clear with the intention of setting it, and when done, clearing it.
 453  */
 454 static inline int wait_on_bit_lock(void *word, int bit,
 455                                 int (*action)(void *), unsigned mode)
 456 {
 457         if (!test_and_set_bit(bit, word))
 458                 return 0;
 459         return out_of_line_wait_on_bit_lock(word, bit, action, mode);
 460 }
 461
 462 #endif /* __KERNEL__ */
 463
 464 #endif