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