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         void *private;
  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 struct task_struct;
  58
  59 /*
  60  * Macros for declaration and initialisaton of the datatypes
  61  */
  62
  63 #define __WAITQUEUE_INITIALIZER(name, tsk) {                            \
  64         .private        = tsk,                                          \
  65         .func           = default_wake_function,                        \
  66         .task_list      = { NULL, NULL } }
  67
  68 #define DECLARE_WAITQUEUE(name, tsk)                                    \
  69         wait_queue_t name = __WAITQUEUE_INITIALIZER(name, tsk)
  70
  71 #define __WAIT_QUEUE_HEAD_INITIALIZER(name) {                           \
  72         .lock           = SPIN_LOCK_UNLOCKED,                           \
  73         .task_list      = { &(name).task_list, &(name).task_list } }
  74
  75 #define DECLARE_WAIT_QUEUE_HEAD(name) \
  76         wait_queue_head_t name = __WAIT_QUEUE_HEAD_INITIALIZER(name)
  77
  78 #define __WAIT_BIT_KEY_INITIALIZER(word, bit)                           \
  79         { .flags = word, .bit_nr = bit, }
  80
  81 static inline void init_waitqueue_head(wait_queue_head_t *q)
  82 {
  83         spin_lock_init(&q->lock);
  84         INIT_LIST_HEAD(&q->task_list);
  85 }
  86
  87 static inline void init_waitqueue_entry(wait_queue_t *q, struct task_struct *p)
  88 {
  89         q->flags = 0;
  90         q->private = p;
  91         q->func = default_wake_function;
  92 }
  93
  94 static inline void init_waitqueue_func_entry(wait_queue_t *q,
  95                                         wait_queue_func_t func)
  96 {
  97         q->flags = 0;
  98         q->private = NULL;
  99         q->func = func;
 100 }
 101
 102 static inline int waitqueue_active(wait_queue_head_t *q)
 103 {
 104         return !list_empty(&q->task_list);
 105 }
 106
 107 /*
 108  * Used to distinguish between sync and async io wait context:
 109  * sync i/o typically specifies a NULL wait queue entry or a wait
 110  * queue entry bound to a task (current task) to wake up.
 111  * aio specifies a wait queue entry with an async notification
 112  * callback routine, not associated with any task.
 113  */
 114 #define is_sync_wait(wait)      (!(wait) || ((wait)->private))
 115
 116 extern void FASTCALL(add_wait_queue(wait_queue_head_t *q, wait_queue_t * wait));
 117 extern void FASTCALL(add_wait_queue_exclusive(wait_queue_head_t *q, wait_queue_t * wait));
 118 extern void FASTCALL(remove_wait_queue(wait_queue_head_t *q, wait_queue_t * wait));
 119
 120 static inline void __add_wait_queue(wait_queue_head_t *head, wait_queue_t *new)
 121 {
 122         list_add(&new->task_list, &head->task_list);
 123 }
 124
 125 /*
 126  * Used for wake-one threads:
 127  */
 128 static inline void __add_wait_queue_tail(wait_queue_head_t *head,
 129                                                 wait_queue_t *new)
 130 {
 131         list_add_tail(&new->task_list, &head->task_list);
 132 }
 133
 134 static inline void __remove_wait_queue(wait_queue_head_t *head,
 135                                                         wait_queue_t *old)
 136 {
 137         list_del(&old->task_list);
 138 }
 139
 140 void FASTCALL(__wake_up(wait_queue_head_t *q, unsigned int mode, int nr, void *key));
 141 extern void FASTCALL(__wake_up_locked(wait_queue_head_t *q, unsigned int mode));
 142 extern void FASTCALL(__wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr));
 143 void FASTCALL(__wake_up_bit(wait_queue_head_t *, void *, int));
 144 int FASTCALL(__wait_on_bit(wait_queue_head_t *, struct wait_bit_queue *, int (*)(void *), unsigned));
 145 int FASTCALL(__wait_on_bit_lock(wait_queue_head_t *, struct wait_bit_queue *, int (*)(void *), unsigned));
 146 void FASTCALL(wake_up_bit(void *, int));
 147 int FASTCALL(out_of_line_wait_on_bit(void *, int, int (*)(void *), unsigned));
 148 int FASTCALL(out_of_line_wait_on_bit_lock(void *, int, int (*)(void *), unsigned));
 149 wait_queue_head_t *FASTCALL(bit_waitqueue(void *, int));
 150
 151 #define wake_up(x)                      __wake_up(x, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE, 1, NULL)
 152 #define wake_up_nr(x, nr)               __wake_up(x, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE, nr, NULL)
 153 #define wake_up_all(x)                  __wake_up(x, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE, 0, NULL)
 154 #define wake_up_interruptible(x)        __wake_up(x, TASK_INTERRUPTIBLE, 1, NULL)
 155 #define wake_up_interruptible_nr(x, nr) __wake_up(x, TASK_INTERRUPTIBLE, nr, NULL)
 156 #define wake_up_interruptible_all(x)    __wake_up(x, TASK_INTERRUPTIBLE, 0, NULL)
 157 #define wake_up_locked(x)               __wake_up_locked((x), TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE)
 158 #define wake_up_interruptible_sync(x)   __wake_up_sync((x),TASK_INTERRUPTIBLE, 1)
 159
 160 #define __wait_event(wq, condition)                                     \
 161 do {                                                                    \
 162         DEFINE_WAIT(__wait);                                            \
 163                                                                         \
 164         for (;;) {                                                      \
 165                 prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE);    \
 166                 if (condition)                                          \
 167                         break;                                          \
 168                 schedule();                                             \
 169         }                                                               \
 170         finish_wait(&wq, &__wait);                                      \
 171 } while (0)
 172
 173 /**
 174  * wait_event - sleep until a condition gets true
 175  * @wq: the waitqueue to wait on
 176  * @condition: a C expression for the event to wait for
 177  *
 178  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 179  * @condition evaluates to true. The @condition is checked each time
 180  * the waitqueue @wq is woken up.
 181  *
 182  * wake_up() has to be called after changing any variable that could
 183  * change the result of the wait condition.
 184  */
 185 #define wait_event(wq, condition)                                       \
 186 do {                                                                    \
 187         if (condition)                                                  \
 188                 break;                                                  \
 189         __wait_event(wq, condition);                                    \
 190 } while (0)
 191
 192 #define __wait_event_timeout(wq, condition, ret)                        \
 193 do {                                                                    \
 194         DEFINE_WAIT(__wait);                                            \
 195                                                                         \
 196         for (;;) {                                                      \
 197                 prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE);    \
 198                 if (condition)                                          \
 199                         break;                                          \
 200                 ret = schedule_timeout(ret);                            \
 201                 if (!ret)                                               \
 202                         break;                                          \
 203         }                                                               \
 204         finish_wait(&wq, &__wait);                                      \
 205 } while (0)
 206
 207 /**
 208  * wait_event_timeout - sleep until a condition gets true or a timeout elapses
 209  * @wq: the waitqueue to wait on
 210  * @condition: a C expression for the event to wait for
 211  * @timeout: timeout, in jiffies
 212  *
 213  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 214  * @condition evaluates to true. The @condition is checked each time
 215  * the waitqueue @wq is woken up.
 216  *
 217  * wake_up() has to be called after changing any variable that could
 218  * change the result of the wait condition.
 219  *
 220  * The function returns 0 if the @timeout elapsed, and the remaining
 221  * jiffies if the condition evaluated to true before the timeout elapsed.
 222  */
 223 #define wait_event_timeout(wq, condition, timeout)                      \
 224 ({                                                                      \
 225         long __ret = timeout;                                           \
 226         if (!(condition))                                               \
 227                 __wait_event_timeout(wq, condition, __ret);             \
 228         __ret;                                                          \
 229 })
 230
 231 #define __wait_event_interruptible(wq, condition, ret)                  \
 232 do {                                                                    \
 233         DEFINE_WAIT(__wait);                                            \
 234                                                                         \
 235         for (;;) {                                                      \
 236                 prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE);      \
 237                 if (condition)                                          \
 238                         break;                                          \
 239                 if (!signal_pending(current)) {                         \
 240                         schedule();                                     \
 241                         continue;                                       \
 242                 }                                                       \
 243                 ret = -ERESTARTSYS;                                     \
 244                 break;                                                  \
 245         }                                                               \
 246         finish_wait(&wq, &__wait);                                      \
 247 } while (0)
 248
 249 /**
 250  * wait_event_interruptible - sleep until a condition gets true
 251  * @wq: the waitqueue to wait on
 252  * @condition: a C expression for the event to wait for
 253  *
 254  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 255  * @condition evaluates to true or a signal is received.
 256  * The @condition is checked each time the waitqueue @wq is woken up.
 257  *
 258  * wake_up() has to be called after changing any variable that could
 259  * change the result of the wait condition.
 260  *
 261  * The function will return -ERESTARTSYS if it was interrupted by a
 262  * signal and 0 if @condition evaluated to true.
 263  */
 264 #define wait_event_interruptible(wq, condition)                         \
 265 ({                                                                      \
 266         int __ret = 0;                                                  \
 267         if (!(condition))                                               \
 268                 __wait_event_interruptible(wq, condition, __ret);       \
 269         __ret;                                                          \
 270 })
 271
 272 #define __wait_event_interruptible_timeout(wq, condition, ret)          \
 273 do {                                                                    \
 274         DEFINE_WAIT(__wait);                                            \
 275                                                                         \
 276         for (;;) {                                                      \
 277                 prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE);      \
 278                 if (condition)                                          \
 279                         break;                                          \
 280                 if (!signal_pending(current)) {                         \
 281                         ret = schedule_timeout(ret);                    \
 282                         if (!ret)                                       \
 283                                 break;                                  \
 284                         continue;                                       \
 285                 }                                                       \
 286                 ret = -ERESTARTSYS;                                     \
 287                 break;                                                  \
 288         }                                                               \
 289         finish_wait(&wq, &__wait);                                      \
 290 } while (0)
 291
 292 /**
 293  * wait_event_interruptible_timeout - sleep until a condition gets true or a timeout elapses
 294  * @wq: the waitqueue to wait on
 295  * @condition: a C expression for the event to wait for
 296  * @timeout: timeout, in jiffies
 297  *
 298  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 299  * @condition evaluates to true or a signal is received.
 300  * The @condition is checked each time the waitqueue @wq is woken up.
 301  *
 302  * wake_up() has to be called after changing any variable that could
 303  * change the result of the wait condition.
 304  *
 305  * The function returns 0 if the @timeout elapsed, -ERESTARTSYS if it
 306  * was interrupted by a signal, and the remaining jiffies otherwise
 307  * if the condition evaluated to true before the timeout elapsed.
 308  */
 309 #define wait_event_interruptible_timeout(wq, condition, timeout)        \
 310 ({                                                                      \
 311         long __ret = timeout;                                           \
 312         if (!(condition))                                               \
 313                 __wait_event_interruptible_timeout(wq, condition, __ret); \
 314         __ret;                                                          \
 315 })
 316
 317 #define __wait_event_interruptible_exclusive(wq, condition, ret)        \
 318 do {                                                                    \
 319         DEFINE_WAIT(__wait);                                            \
 320                                                                         \
 321         for (;;) {                                                      \
 322                 prepare_to_wait_exclusive(&wq, &__wait,                 \
 323                                         TASK_INTERRUPTIBLE);            \
 324                 if (condition)                                          \
 325                         break;                                          \
 326                 if (!signal_pending(current)) {                         \
 327                         schedule();                                     \
 328                         continue;                                       \
 329                 }                                                       \
 330                 ret = -ERESTARTSYS;                                     \
 331                 break;                                                  \
 332         }                                                               \
 333         finish_wait(&wq, &__wait);                                      \
 334 } while (0)
 335
 336 #define wait_event_interruptible_exclusive(wq, condition)               \
 337 ({                                                                      \
 338         int __ret = 0;                                                  \
 339         if (!(condition))                                               \
 340                 __wait_event_interruptible_exclusive(wq, condition, __ret);\
 341         __ret;                                                          \
 342 })
 343
 344 /*
 345  * Must be called with the spinlock in the wait_queue_head_t held.
 346  */
 347 static inline void add_wait_queue_exclusive_locked(wait_queue_head_t *q,
 348                                                    wait_queue_t * wait)
 349 {
 350         wait->flags |= WQ_FLAG_EXCLUSIVE;
 351         __add_wait_queue_tail(q,  wait);
 352 }
 353
 354 /*
 355  * Must be called with the spinlock in the wait_queue_head_t held.
 356  */
 357 static inline void remove_wait_queue_locked(wait_queue_head_t *q,
 358                                             wait_queue_t * wait)
 359 {
 360         __remove_wait_queue(q,  wait);
 361 }
 362
 363 /*
 364  * These are the old interfaces to sleep waiting for an event.
 365  * They are racy.  DO NOT use them, use the wait_event* interfaces above.
 366  * We plan to remove these interfaces during 2.7.
 367  */
 368 extern void FASTCALL(sleep_on(wait_queue_head_t *q));
 369 extern long FASTCALL(sleep_on_timeout(wait_queue_head_t *q,
 370                                       signed long timeout));
 371 extern void FASTCALL(interruptible_sleep_on(wait_queue_head_t *q));
 372 extern long FASTCALL(interruptible_sleep_on_timeout(wait_queue_head_t *q,
 373                                                     signed long timeout));
 374
 375 /*
 376  * Waitqueues which are removed from the waitqueue_head at wakeup time
 377  */
 378 void FASTCALL(prepare_to_wait(wait_queue_head_t *q,
 379                                 wait_queue_t *wait, int state));
 380 void FASTCALL(prepare_to_wait_exclusive(wait_queue_head_t *q,
 381                                 wait_queue_t *wait, int state));
 382 void FASTCALL(finish_wait(wait_queue_head_t *q, wait_queue_t *wait));
 383 int autoremove_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 384 int wake_bit_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 385
 386 #define DEFINE_WAIT(name)                                               \
 387         wait_queue_t name = {                                           \
 388                 .private        = current,                              \
 389                 .func           = autoremove_wake_function,             \
 390                 .task_list      = LIST_HEAD_INIT((name).task_list),     \
 391         }
 392
 393 #define DEFINE_WAIT_BIT(name, word, bit)                                \
 394         struct wait_bit_queue name = {                                  \
 395                 .key = __WAIT_BIT_KEY_INITIALIZER(word, bit),           \
 396                 .wait   = {                                             \
 397                         .private        = current,                      \
 398                         .func           = wake_bit_function,            \
 399                         .task_list      =                               \
 400                                 LIST_HEAD_INIT((name).wait.task_list),  \
 401                 },                                                      \
 402         }
 403
 404 #define init_wait(wait)                                                 \
 405         do {                                                            \
 406                 (wait)->private = current;                              \
 407                 (wait)->func = autoremove_wake_function;                \
 408                 INIT_LIST_HEAD(&(wait)->task_list);                     \
 409         } while (0)
 410
 411 /**
 412  * wait_on_bit - wait for a bit to be cleared
 413  * @word: the word being waited on, a kernel virtual address
 414  * @bit: the bit of the word being waited on
 415  * @action: the function used to sleep, which may take special actions
 416  * @mode: the task state to sleep in
 417  *
 418  * There is a standard hashed waitqueue table for generic use. This
 419  * is the part of the hashtable's accessor API that waits on a bit.
 420  * For instance, if one were to have waiters on a bitflag, one would
 421  * call wait_on_bit() in threads waiting for the bit to clear.
 422  * One uses wait_on_bit() where one is waiting for the bit to clear,
 423  * but has no intention of setting it.
 424  */
 425 static inline int wait_on_bit(void *word, int bit,
 426                                 int (*action)(void *), unsigned mode)
 427 {
 428         if (!test_bit(bit, word))
 429                 return 0;
 430         return out_of_line_wait_on_bit(word, bit, action, mode);
 431 }
 432
 433 /**
 434  * wait_on_bit_lock - wait for a bit to be cleared, when wanting to set it
 435  * @word: the word being waited on, a kernel virtual address
 436  * @bit: the bit of the word being waited on
 437  * @action: the function used to sleep, which may take special actions
 438  * @mode: the task state to sleep in
 439  *
 440  * There is a standard hashed waitqueue table for generic use. This
 441  * is the part of the hashtable's accessor API that waits on a bit
 442  * when one intends to set it, for instance, trying to lock bitflags.
 443  * For instance, if one were to have waiters trying to set bitflag
 444  * and waiting for it to clear before setting it, one would call
 445  * wait_on_bit() in threads waiting to be able to set the bit.
 446  * One uses wait_on_bit_lock() where one is waiting for the bit to
 447  * clear with the intention of setting it, and when done, clearing it.
 448  */
 449 static inline int wait_on_bit_lock(void *word, int bit,
 450                                 int (*action)(void *), unsigned mode)
 451 {
 452         if (!test_and_set_bit(bit, word))
 453                 return 0;
 454         return out_of_line_wait_on_bit_lock(word, bit, action, mode);
 455 }
 456
 457 #endif /* __KERNEL__ */
 458
 459 #endif