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/config.h>
  23 #include <linux/list.h>
  24 #include <linux/stddef.h>
  25 #include <linux/spinlock.h>
  26 #include <asm/system.h>
  27 #include <asm/current.h>
  28
  29 typedef struct __wait_queue wait_queue_t;
  30 typedef int (*wait_queue_func_t)(wait_queue_t *wait, unsigned mode, int sync, void *key);
  31 int default_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
  32
  33 struct __wait_queue {
  34         unsigned int flags;
  35 #define WQ_FLAG_EXCLUSIVE       0x01
  36         struct task_struct * task;
  37         wait_queue_func_t func;
  38         struct list_head task_list;
  39 };
  40
  41 struct wait_bit_key {
  42         void *flags;
  43         int bit_nr;
  44 };
  45
  46 struct wait_bit_queue {
  47         struct wait_bit_key key;
  48         wait_queue_t wait;
  49 };
  50
  51 struct __wait_queue_head {
  52         spinlock_t lock;
  53         struct list_head task_list;
  54 };
  55 typedef struct __wait_queue_head wait_queue_head_t;
  56
  57
  58 /*
  59  * Macros for declaration and initialisaton of the datatypes
  60  */
  61
  62 #define __WAITQUEUE_INITIALIZER(name, tsk) {                            \
  63         .task           = 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,                           \
  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 static inline void init_waitqueue_head(wait_queue_head_t *q)
  81 {
  82         spin_lock_init(&q->lock);
  83         INIT_LIST_HEAD(&q->task_list);
  84 }
  85
  86 static inline void init_waitqueue_entry(wait_queue_t *q, struct task_struct *p)
  87 {
  88         q->flags = 0;
  89         q->task = p;
  90         q->func = default_wake_function;
  91 }
  92
  93 static inline void init_waitqueue_func_entry(wait_queue_t *q,
  94                                         wait_queue_func_t func)
  95 {
  96         q->flags = 0;
  97         q->task = NULL;
  98         q->func = func;
  99 }
 100
 101 static inline int waitqueue_active(wait_queue_head_t *q)
 102 {
 103         return !list_empty(&q->task_list);
 104 }
 105
 106 /*
 107  * Used to distinguish between sync and async io wait context:
 108  * sync i/o typically specifies a NULL wait queue entry or a wait
 109  * queue entry bound to a task (current task) to wake up.
 110  * aio specifies a wait queue entry with an async notification
 111  * callback routine, not associated with any task.
 112  */
 113 #define is_sync_wait(wait)      (!(wait) || ((wait)->task))
 114
 115 extern void FASTCALL(add_wait_queue(wait_queue_head_t *q, wait_queue_t * wait));
 116 extern void FASTCALL(add_wait_queue_exclusive(wait_queue_head_t *q, wait_queue_t * wait));
 117 extern void FASTCALL(remove_wait_queue(wait_queue_head_t *q, wait_queue_t * wait));
 118
 119 static inline void __add_wait_queue(wait_queue_head_t *head, wait_queue_t *new)
 120 {
 121         list_add(&new->task_list, &head->task_list);
 122 }
 123
 124 /*
 125  * Used for wake-one threads:
 126  */
 127 static inline void __add_wait_queue_tail(wait_queue_head_t *head,
 128                                                 wait_queue_t *new)
 129 {
 130         list_add_tail(&new->task_list, &head->task_list);
 131 }
 132
 133 static inline void __remove_wait_queue(wait_queue_head_t *head,
 134                                                         wait_queue_t *old)
 135 {
 136         list_del(&old->task_list);
 137 }
 138
 139 void FASTCALL(__wake_up(wait_queue_head_t *q, unsigned int mode, int nr, void *key));
 140 extern void FASTCALL(__wake_up_locked(wait_queue_head_t *q, unsigned int mode));
 141 extern void FASTCALL(__wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr));
 142 void FASTCALL(__wake_up_bit(wait_queue_head_t *, void *, int));
 143 int FASTCALL(__wait_on_bit(wait_queue_head_t *, struct wait_bit_queue *, int (*)(void *), unsigned));
 144 int FASTCALL(__wait_on_bit_lock(wait_queue_head_t *, struct wait_bit_queue *, int (*)(void *), unsigned));
 145 void FASTCALL(wake_up_bit(void *, int));
 146 int FASTCALL(out_of_line_wait_on_bit(void *, int, int (*)(void *), unsigned));
 147 int FASTCALL(out_of_line_wait_on_bit_lock(void *, int, int (*)(void *), unsigned));
 148 wait_queue_head_t *FASTCALL(bit_waitqueue(void *, int));
 149
 150 #define wake_up(x)                      __wake_up(x, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE, 1, NULL)
 151 #define wake_up_nr(x, nr)               __wake_up(x, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE, nr, NULL)
 152 #define wake_up_all(x)                  __wake_up(x, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE, 0, NULL)
 153 #define wake_up_interruptible(x)        __wake_up(x, TASK_INTERRUPTIBLE, 1, NULL)
 154 #define wake_up_interruptible_nr(x, nr) __wake_up(x, TASK_INTERRUPTIBLE, nr, NULL)
 155 #define wake_up_interruptible_all(x)    __wake_up(x, TASK_INTERRUPTIBLE, 0, NULL)
 156 #define wake_up_locked(x)               __wake_up_locked((x), TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE)
 157 #define wake_up_interruptible_sync(x)   __wake_up_sync((x),TASK_INTERRUPTIBLE, 1)
 158
 159 #define __wait_event(wq, condition)                                     \
 160 do {                                                                    \
 161         DEFINE_WAIT(__wait);                                            \
 162                                                                         \
 163         for (;;) {                                                      \
 164                 prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE);    \
 165                 if (condition)                                          \
 166                         break;                                          \
 167                 schedule();                                             \
 168         }                                                               \
 169         finish_wait(&wq, &__wait);                                      \
 170 } while (0)
 171
 172 /**
 173  * wait_event - sleep until a condition gets true
 174  * @wq: the waitqueue to wait on
 175  * @condition: a C expression for the event to wait for
 176  *
 177  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 178  * @condition evaluates to true. The @condition is checked each time
 179  * the waitqueue @wq is woken up.
 180  *
 181  * wake_up() has to be called after changing any variable that could
 182  * change the result of the wait condition.
 183  */
 184 #define wait_event(wq, condition)                                       \
 185 do {                                                                    \
 186         if (condition)                                                  \
 187                 break;                                                  \
 188         __wait_event(wq, condition);                                    \
 189 } while (0)
 190
 191 #define __wait_event_timeout(wq, condition, ret)                        \
 192 do {                                                                    \
 193         DEFINE_WAIT(__wait);                                            \
 194                                                                         \
 195         for (;;) {                                                      \
 196                 prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE);    \
 197                 if (condition)                                          \
 198                         break;                                          \
 199                 ret = schedule_timeout(ret);                            \
 200                 if (!ret)                                               \
 201                         break;                                          \
 202         }                                                               \
 203         finish_wait(&wq, &__wait);                                      \
 204 } while (0)
 205
 206 /**
 207  * wait_event_timeout - sleep until a condition gets true or a timeout elapses
 208  * @wq: the waitqueue to wait on
 209  * @condition: a C expression for the event to wait for
 210  * @timeout: timeout, in jiffies
 211  *
 212  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 213  * @condition evaluates to true. The @condition is checked each time
 214  * the waitqueue @wq is woken up.
 215  *
 216  * wake_up() has to be called after changing any variable that could
 217  * change the result of the wait condition.
 218  *
 219  * The function returns 0 if the @timeout elapsed, and the remaining
 220  * jiffies if the condition evaluated to true before the timeout elapsed.
 221  */
 222 #define wait_event_timeout(wq, condition, timeout)                      \
 223 ({                                                                      \
 224         long __ret = timeout;                                           \
 225         if (!(condition))                                               \
 226                 __wait_event_timeout(wq, condition, __ret);             \
 227         __ret;                                                          \
 228 })
 229
 230 #define __wait_event_interruptible(wq, condition, ret)                  \
 231 do {                                                                    \
 232         DEFINE_WAIT(__wait);                                            \
 233                                                                         \
 234         for (;;) {                                                      \
 235                 prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE);      \
 236                 if (condition)                                          \
 237                         break;                                          \
 238                 if (!signal_pending(current)) {                         \
 239                         schedule();                                     \
 240                         continue;                                       \
 241                 }                                                       \
 242                 ret = -ERESTARTSYS;                                     \
 243                 break;                                                  \
 244         }                                                               \
 245         finish_wait(&wq, &__wait);                                      \
 246 } while (0)
 247
 248 /**
 249  * wait_event_interruptible - sleep until a condition gets true
 250  * @wq: the waitqueue to wait on
 251  * @condition: a C expression for the event to wait for
 252  *
 253  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 254  * @condition evaluates to true or a signal is received.
 255  * The @condition is checked each time the waitqueue @wq is woken up.
 256  *
 257  * wake_up() has to be called after changing any variable that could
 258  * change the result of the wait condition.
 259  *
 260  * The function will return -ERESTARTSYS if it was interrupted by a
 261  * signal and 0 if @condition evaluated to true.
 262  */
 263 #define wait_event_interruptible(wq, condition)                         \
 264 ({                                                                      \
 265         int __ret = 0;                                                  \
 266         if (!(condition))                                               \
 267                 __wait_event_interruptible(wq, condition, __ret);       \
 268         __ret;                                                          \
 269 })
 270
 271 #define __wait_event_interruptible_timeout(wq, condition, ret)          \
 272 do {                                                                    \
 273         DEFINE_WAIT(__wait);                                            \
 274                                                                         \
 275         for (;;) {                                                      \
 276                 prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE);      \
 277                 if (condition)                                          \
 278                         break;                                          \
 279                 if (!signal_pending(current)) {                         \
 280                         ret = schedule_timeout(ret);                    \
 281                         if (!ret)                                       \
 282                                 break;                                  \
 283                         continue;                                       \
 284                 }                                                       \
 285                 ret = -ERESTARTSYS;                                     \
 286                 break;                                                  \
 287         }                                                               \
 288         finish_wait(&wq, &__wait);                                      \
 289 } while (0)
 290
 291 /**
 292  * wait_event_interruptible_timeout - sleep until a condition gets true or a timeout elapses
 293  * @wq: the waitqueue to wait on
 294  * @condition: a C expression for the event to wait for
 295  * @timeout: timeout, in jiffies
 296  *
 297  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 298  * @condition evaluates to true or a signal is received.
 299  * The @condition is checked each time the waitqueue @wq is woken up.
 300  *
 301  * wake_up() has to be called after changing any variable that could
 302  * change the result of the wait condition.
 303  *
 304  * The function returns 0 if the @timeout elapsed, -ERESTARTSYS if it
 305  * was interrupted by a signal, and the remaining jiffies otherwise
 306  * if the condition evaluated to true before the timeout elapsed.
 307  */
 308 #define wait_event_interruptible_timeout(wq, condition, timeout)        \
 309 ({                                                                      \
 310         long __ret = timeout;                                           \
 311         if (!(condition))                                               \
 312                 __wait_event_interruptible_timeout(wq, condition, __ret); \
 313         __ret;                                                          \
 314 })
 315
 316 #define __wait_event_interruptible_exclusive(wq, condition, ret)        \
 317 do {                                                                    \
 318         DEFINE_WAIT(__wait);                                            \
 319                                                                         \
 320         for (;;) {                                                      \
 321                 prepare_to_wait_exclusive(&wq, &__wait,                 \
 322                                         TASK_INTERRUPTIBLE);            \
 323                 if (condition)                                          \
 324                         break;                                          \
 325                 if (!signal_pending(current)) {                         \
 326                         schedule();                                     \
 327                         continue;                                       \
 328                 }                                                       \
 329                 ret = -ERESTARTSYS;                                     \
 330                 break;                                                  \
 331         }                                                               \
 332         finish_wait(&wq, &__wait);                                      \
 333 } while (0)
 334
 335 #define wait_event_interruptible_exclusive(wq, condition)               \
 336 ({                                                                      \
 337         int __ret = 0;                                                  \
 338         if (!(condition))                                               \
 339                 __wait_event_interruptible_exclusive(wq, condition, __ret);\
 340         __ret;                                                          \
 341 })
 342
 343 /*
 344  * Must be called with the spinlock in the wait_queue_head_t held.
 345  */
 346 static inline void add_wait_queue_exclusive_locked(wait_queue_head_t *q,
 347                                                    wait_queue_t * wait)
 348 {
 349         wait->flags |= WQ_FLAG_EXCLUSIVE;
 350         __add_wait_queue_tail(q,  wait);
 351 }
 352
 353 /*
 354  * Must be called with the spinlock in the wait_queue_head_t held.
 355  */
 356 static inline void remove_wait_queue_locked(wait_queue_head_t *q,
 357                                             wait_queue_t * wait)
 358 {
 359         __remove_wait_queue(q,  wait);
 360 }
 361
 362 /*
 363  * These are the old interfaces to sleep waiting for an event.
 364  * They are racy.  DO NOT use them, use the wait_event* interfaces above.
 365  * We plan to remove these interfaces during 2.7.
 366  */
 367 extern void FASTCALL(sleep_on(wait_queue_head_t *q));
 368 extern long FASTCALL(sleep_on_timeout(wait_queue_head_t *q,
 369                                       signed long timeout));
 370 extern void FASTCALL(interruptible_sleep_on(wait_queue_head_t *q));
 371 extern long FASTCALL(interruptible_sleep_on_timeout(wait_queue_head_t *q,
 372                                                     signed long timeout));
 373
 374 /*
 375  * Waitqueues which are removed from the waitqueue_head at wakeup time
 376  */
 377 void FASTCALL(prepare_to_wait(wait_queue_head_t *q,
 378                                 wait_queue_t *wait, int state));
 379 void FASTCALL(prepare_to_wait_exclusive(wait_queue_head_t *q,
 380                                 wait_queue_t *wait, int state));
 381 void FASTCALL(finish_wait(wait_queue_head_t *q, wait_queue_t *wait));
 382 int autoremove_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 383 int wake_bit_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 384
 385 #define DEFINE_WAIT(name)                                               \
 386         wait_queue_t name = {                                           \
 387                 .task           = current,                              \
 388                 .func           = autoremove_wake_function,             \
 389                 .task_list      = {     .next = &(name).task_list,      \
 390                                         .prev = &(name).task_list,      \
 391                                 },                                      \
 392         }
 393
 394 #define DEFINE_WAIT_BIT(name, word, bit)                                \
 395         struct wait_bit_queue name = {                                  \
 396                 .key = __WAIT_BIT_KEY_INITIALIZER(word, bit),           \
 397                 .wait   = {                                             \
 398                         .task           = current,                      \
 399                         .func           = wake_bit_function,            \
 400                         .task_list      =                               \
 401                                 LIST_HEAD_INIT((name).wait.task_list),  \
 402                 },                                                      \
 403         }
 404
 405 #define init_wait(wait)                                                 \
 406         do {                                                            \
 407                 (wait)->task = current;                                 \
 408                 (wait)->func = autoremove_wake_function;                \
 409                 INIT_LIST_HEAD(&(wait)->task_list);                     \
 410         } while (0)
 411
 412 /**
 413  * wait_on_bit - wait for a bit to be cleared
 414  * @word: the word being waited on, a kernel virtual address
 415  * @bit: the bit of the word being waited on
 416  * @action: the function used to sleep, which may take special actions
 417  * @mode: the task state to sleep in
 418  *
 419  * There is a standard hashed waitqueue table for generic use. This
 420  * is the part of the hashtable's accessor API that waits on a bit.
 421  * For instance, if one were to have waiters on a bitflag, one would
 422  * call wait_on_bit() in threads waiting for the bit to clear.
 423  * One uses wait_on_bit() where one is waiting for the bit to clear,
 424  * but has no intention of setting it.
 425  */
 426 static inline int wait_on_bit(void *word, int bit,
 427                                 int (*action)(void *), unsigned mode)
 428 {
 429         if (!test_bit(bit, word))
 430                 return 0;
 431         return out_of_line_wait_on_bit(word, bit, action, mode);
 432 }
 433
 434 /**
 435  * wait_on_bit_lock - wait for a bit to be cleared, when wanting to set it
 436  * @word: the word being waited on, a kernel virtual address
 437  * @bit: the bit of the word being waited on
 438  * @action: the function used to sleep, which may take special actions
 439  * @mode: the task state to sleep in
 440  *
 441  * There is a standard hashed waitqueue table for generic use. This
 442  * is the part of the hashtable's accessor API that waits on a bit
 443  * when one intends to set it, for instance, trying to lock bitflags.
 444  * For instance, if one were to have waiters trying to set bitflag
 445  * and waiting for it to clear before setting it, one would call
 446  * wait_on_bit() in threads waiting to be able to set the bit.
 447  * One uses wait_on_bit_lock() where one is waiting for the bit to
 448  * clear with the intention of setting it, and when done, clearing it.
 449  */
 450 static inline int wait_on_bit_lock(void *word, int bit,
 451                                 int (*action)(void *), unsigned mode)
 452 {
 453         if (!test_and_set_bit(bit, word))
 454                 return 0;
 455         return out_of_line_wait_on_bit_lock(word, bit, action, mode);
 456 }
 457
 458 #endif /* __KERNEL__ */
 459
 460 #endif