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 flags, void *key);
  30 int default_wake_function(wait_queue_t *wait, unsigned mode, int flags, 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, struct lock_class_key *);
  81
  82 #define init_waitqueue_head(q)                          \
  83         do {                                            \
  84                 static struct lock_class_key __key;     \
  85                                                         \
  86                 __init_waitqueue_head((q), &__key);     \
  87         } while (0)
  88
  89 #ifdef CONFIG_LOCKDEP
  90 # define __WAIT_QUEUE_HEAD_INIT_ONSTACK(name) \
  91         ({ init_waitqueue_head(&name); name; })
  92 # define DECLARE_WAIT_QUEUE_HEAD_ONSTACK(name) \
  93         wait_queue_head_t name = __WAIT_QUEUE_HEAD_INIT_ONSTACK(name)
  94 #else
  95 # define DECLARE_WAIT_QUEUE_HEAD_ONSTACK(name) DECLARE_WAIT_QUEUE_HEAD(name)
  96 #endif
  97
  98 static inline void init_waitqueue_entry(wait_queue_t *q, struct task_struct *p)
  99 {
 100         q->flags = 0;
 101         q->private = p;
 102         q->func = default_wake_function;
 103 }
 104
 105 static inline void init_waitqueue_func_entry(wait_queue_t *q,
 106                                         wait_queue_func_t func)
 107 {
 108         q->flags = 0;
 109         q->private = NULL;
 110         q->func = func;
 111 }
 112
 113 static inline int waitqueue_active(wait_queue_head_t *q)
 114 {
 115         return !list_empty(&q->task_list);
 116 }
 117
 118 extern void add_wait_queue(wait_queue_head_t *q, wait_queue_t *wait);
 119 extern void add_wait_queue_exclusive(wait_queue_head_t *q, wait_queue_t *wait);
 120 extern void remove_wait_queue(wait_queue_head_t *q, wait_queue_t *wait);
 121
 122 static inline void __add_wait_queue(wait_queue_head_t *head, wait_queue_t *new)
 123 {
 124         list_add(&new->task_list, &head->task_list);
 125 }
 126
 127 /*
 128  * Used for wake-one threads:
 129  */
 130 static inline void __add_wait_queue_exclusive(wait_queue_head_t *q,
 131                                               wait_queue_t *wait)
 132 {
 133         wait->flags |= WQ_FLAG_EXCLUSIVE;
 134         __add_wait_queue(q, wait);
 135 }
 136
 137 static inline void __add_wait_queue_tail(wait_queue_head_t *head,
 138                                          wait_queue_t *new)
 139 {
 140         list_add_tail(&new->task_list, &head->task_list);
 141 }
 142
 143 static inline void __add_wait_queue_tail_exclusive(wait_queue_head_t *q,
 144                                               wait_queue_t *wait)
 145 {
 146         wait->flags |= WQ_FLAG_EXCLUSIVE;
 147         __add_wait_queue_tail(q, wait);
 148 }
 149
 150 static inline void __remove_wait_queue(wait_queue_head_t *head,
 151                                                         wait_queue_t *old)
 152 {
 153         list_del(&old->task_list);
 154 }
 155
 156 void __wake_up(wait_queue_head_t *q, unsigned int mode, int nr, void *key);
 157 void __wake_up_locked_key(wait_queue_head_t *q, unsigned int mode, void *key);
 158 void __wake_up_sync_key(wait_queue_head_t *q, unsigned int mode, int nr,
 159                         void *key);
 160 void __wake_up_locked(wait_queue_head_t *q, unsigned int mode);
 161 void __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr);
 162 void __wake_up_bit(wait_queue_head_t *, void *, int);
 163 int __wait_on_bit(wait_queue_head_t *, struct wait_bit_queue *, int (*)(void *), unsigned);
 164 int __wait_on_bit_lock(wait_queue_head_t *, struct wait_bit_queue *, int (*)(void *), unsigned);
 165 void wake_up_bit(void *, int);
 166 int out_of_line_wait_on_bit(void *, int, int (*)(void *), unsigned);
 167 int out_of_line_wait_on_bit_lock(void *, int, int (*)(void *), unsigned);
 168 wait_queue_head_t *bit_waitqueue(void *, int);
 169
 170 #define wake_up(x)                      __wake_up(x, TASK_NORMAL, 1, NULL)
 171 #define wake_up_nr(x, nr)               __wake_up(x, TASK_NORMAL, nr, NULL)
 172 #define wake_up_all(x)                  __wake_up(x, TASK_NORMAL, 0, NULL)
 173 #define wake_up_locked(x)               __wake_up_locked((x), TASK_NORMAL)
 174
 175 #define wake_up_interruptible(x)        __wake_up(x, TASK_INTERRUPTIBLE, 1, NULL)
 176 #define wake_up_interruptible_nr(x, nr) __wake_up(x, TASK_INTERRUPTIBLE, nr, NULL)
 177 #define wake_up_interruptible_all(x)    __wake_up(x, TASK_INTERRUPTIBLE, 0, NULL)
 178 #define wake_up_interruptible_sync(x)   __wake_up_sync((x), TASK_INTERRUPTIBLE, 1)
 179
 180 /*
 181  * Wakeup macros to be used to report events to the targets.
 182  */
 183 #define wake_up_poll(x, m)                              \
 184         __wake_up(x, TASK_NORMAL, 1, (void *) (m))
 185 #define wake_up_locked_poll(x, m)                               \
 186         __wake_up_locked_key((x), TASK_NORMAL, (void *) (m))
 187 #define wake_up_interruptible_poll(x, m)                        \
 188         __wake_up(x, TASK_INTERRUPTIBLE, 1, (void *) (m))
 189 #define wake_up_interruptible_sync_poll(x, m)                           \
 190         __wake_up_sync_key((x), TASK_INTERRUPTIBLE, 1, (void *) (m))
 191
 192 #define __wait_event(wq, condition)                                     \
 193 do {                                                                    \
 194         DEFINE_WAIT(__wait);                                            \
 195                                                                         \
 196         for (;;) {                                                      \
 197                 prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE);    \
 198                 if (condition)                                          \
 199                         break;                                          \
 200                 schedule();                                             \
 201         }                                                               \
 202         finish_wait(&wq, &__wait);                                      \
 203 } while (0)
 204
 205 /**
 206  * wait_event - sleep until a condition gets true
 207  * @wq: the waitqueue to wait on
 208  * @condition: a C expression for the event to wait for
 209  *
 210  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 211  * @condition evaluates to true. The @condition is checked each time
 212  * the waitqueue @wq is woken up.
 213  *
 214  * wake_up() has to be called after changing any variable that could
 215  * change the result of the wait condition.
 216  */
 217 #define wait_event(wq, condition)                                       \
 218 do {                                                                    \
 219         if (condition)                                                  \
 220                 break;                                                  \
 221         __wait_event(wq, condition);                                    \
 222 } while (0)
 223
 224 #define __wait_event_timeout(wq, condition, ret)                        \
 225 do {                                                                    \
 226         DEFINE_WAIT(__wait);                                            \
 227                                                                         \
 228         for (;;) {                                                      \
 229                 prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE);    \
 230                 if (condition)                                          \
 231                         break;                                          \
 232                 ret = schedule_timeout(ret);                            \
 233                 if (!ret)                                               \
 234                         break;                                          \
 235         }                                                               \
 236         finish_wait(&wq, &__wait);                                      \
 237 } while (0)
 238
 239 /**
 240  * wait_event_timeout - sleep until a condition gets true or a timeout elapses
 241  * @wq: the waitqueue to wait on
 242  * @condition: a C expression for the event to wait for
 243  * @timeout: timeout, in jiffies
 244  *
 245  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 246  * @condition evaluates to true. The @condition is checked each time
 247  * the waitqueue @wq is woken up.
 248  *
 249  * wake_up() has to be called after changing any variable that could
 250  * change the result of the wait condition.
 251  *
 252  * The function returns 0 if the @timeout elapsed, and the remaining
 253  * jiffies if the condition evaluated to true before the timeout elapsed.
 254  */
 255 #define wait_event_timeout(wq, condition, timeout)                      \
 256 ({                                                                      \
 257         long __ret = timeout;                                           \
 258         if (!(condition))                                               \
 259                 __wait_event_timeout(wq, condition, __ret);             \
 260         __ret;                                                          \
 261 })
 262
 263 #define __wait_event_interruptible(wq, condition, ret)                  \
 264 do {                                                                    \
 265         DEFINE_WAIT(__wait);                                            \
 266                                                                         \
 267         for (;;) {                                                      \
 268                 prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE);      \
 269                 if (condition)                                          \
 270                         break;                                          \
 271                 if (!signal_pending(current)) {                         \
 272                         schedule();                                     \
 273                         continue;                                       \
 274                 }                                                       \
 275                 ret = -ERESTARTSYS;                                     \
 276                 break;                                                  \
 277         }                                                               \
 278         finish_wait(&wq, &__wait);                                      \
 279 } while (0)
 280
 281 /**
 282  * wait_event_interruptible - sleep until a condition gets true
 283  * @wq: the waitqueue to wait on
 284  * @condition: a C expression for the event to wait for
 285  *
 286  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 287  * @condition evaluates to true or a signal is received.
 288  * The @condition is checked each time the waitqueue @wq is woken up.
 289  *
 290  * wake_up() has to be called after changing any variable that could
 291  * change the result of the wait condition.
 292  *
 293  * The function will return -ERESTARTSYS if it was interrupted by a
 294  * signal and 0 if @condition evaluated to true.
 295  */
 296 #define wait_event_interruptible(wq, condition)                         \
 297 ({                                                                      \
 298         int __ret = 0;                                                  \
 299         if (!(condition))                                               \
 300                 __wait_event_interruptible(wq, condition, __ret);       \
 301         __ret;                                                          \
 302 })
 303
 304 #define __wait_event_interruptible_timeout(wq, condition, ret)          \
 305 do {                                                                    \
 306         DEFINE_WAIT(__wait);                                            \
 307                                                                         \
 308         for (;;) {                                                      \
 309                 prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE);      \
 310                 if (condition)                                          \
 311                         break;                                          \
 312                 if (!signal_pending(current)) {                         \
 313                         ret = schedule_timeout(ret);                    \
 314                         if (!ret)                                       \
 315                                 break;                                  \
 316                         continue;                                       \
 317                 }                                                       \
 318                 ret = -ERESTARTSYS;                                     \
 319                 break;                                                  \
 320         }                                                               \
 321         finish_wait(&wq, &__wait);                                      \
 322 } while (0)
 323
 324 /**
 325  * wait_event_interruptible_timeout - sleep until a condition gets true or a timeout elapses
 326  * @wq: the waitqueue to wait on
 327  * @condition: a C expression for the event to wait for
 328  * @timeout: timeout, in jiffies
 329  *
 330  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 331  * @condition evaluates to true or a signal is received.
 332  * The @condition is checked each time the waitqueue @wq is woken up.
 333  *
 334  * wake_up() has to be called after changing any variable that could
 335  * change the result of the wait condition.
 336  *
 337  * The function returns 0 if the @timeout elapsed, -ERESTARTSYS if it
 338  * was interrupted by a signal, and the remaining jiffies otherwise
 339  * if the condition evaluated to true before the timeout elapsed.
 340  */
 341 #define wait_event_interruptible_timeout(wq, condition, timeout)        \
 342 ({                                                                      \
 343         long __ret = timeout;                                           \
 344         if (!(condition))                                               \
 345                 __wait_event_interruptible_timeout(wq, condition, __ret); \
 346         __ret;                                                          \
 347 })
 348
 349 #define __wait_event_interruptible_exclusive(wq, condition, ret)        \
 350 do {                                                                    \
 351         DEFINE_WAIT(__wait);                                            \
 352                                                                         \
 353         for (;;) {                                                      \
 354                 prepare_to_wait_exclusive(&wq, &__wait,                 \
 355                                         TASK_INTERRUPTIBLE);            \
 356                 if (condition) {                                        \
 357                         finish_wait(&wq, &__wait);                      \
 358                         break;                                          \
 359                 }                                                       \
 360                 if (!signal_pending(current)) {                         \
 361                         schedule();                                     \
 362                         continue;                                       \
 363                 }                                                       \
 364                 ret = -ERESTARTSYS;                                     \
 365                 abort_exclusive_wait(&wq, &__wait,                      \
 366                                 TASK_INTERRUPTIBLE, NULL);              \
 367                 break;                                                  \
 368         }                                                               \
 369 } while (0)
 370
 371 #define wait_event_interruptible_exclusive(wq, condition)               \
 372 ({                                                                      \
 373         int __ret = 0;                                                  \
 374         if (!(condition))                                               \
 375                 __wait_event_interruptible_exclusive(wq, condition, __ret);\
 376         __ret;                                                          \
 377 })
 378
 379 #define __wait_event_killable(wq, condition, ret)                       \
 380 do {                                                                    \
 381         DEFINE_WAIT(__wait);                                            \
 382                                                                         \
 383         for (;;) {                                                      \
 384                 prepare_to_wait(&wq, &__wait, TASK_KILLABLE);           \
 385                 if (condition)                                          \
 386                         break;                                          \
 387                 if (!fatal_signal_pending(current)) {                   \
 388                         schedule();                                     \
 389                         continue;                                       \
 390                 }                                                       \
 391                 ret = -ERESTARTSYS;                                     \
 392                 break;                                                  \
 393         }                                                               \
 394         finish_wait(&wq, &__wait);                                      \
 395 } while (0)
 396
 397 /**
 398  * wait_event_killable - sleep until a condition gets true
 399  * @wq: the waitqueue to wait on
 400  * @condition: a C expression for the event to wait for
 401  *
 402  * The process is put to sleep (TASK_KILLABLE) until the
 403  * @condition evaluates to true or a signal is received.
 404  * The @condition is checked each time the waitqueue @wq is woken up.
 405  *
 406  * wake_up() has to be called after changing any variable that could
 407  * change the result of the wait condition.
 408  *
 409  * The function will return -ERESTARTSYS if it was interrupted by a
 410  * signal and 0 if @condition evaluated to true.
 411  */
 412 #define wait_event_killable(wq, condition)                              \
 413 ({                                                                      \
 414         int __ret = 0;                                                  \
 415         if (!(condition))                                               \
 416                 __wait_event_killable(wq, condition, __ret);            \
 417         __ret;                                                          \
 418 })
 419
 420 /*
 421  * These are the old interfaces to sleep waiting for an event.
 422  * They are racy.  DO NOT use them, use the wait_event* interfaces above.
 423  * We plan to remove these interfaces.
 424  */
 425 extern void sleep_on(wait_queue_head_t *q);
 426 extern long sleep_on_timeout(wait_queue_head_t *q,
 427                                       signed long timeout);
 428 extern void interruptible_sleep_on(wait_queue_head_t *q);
 429 extern long interruptible_sleep_on_timeout(wait_queue_head_t *q,
 430                                            signed long timeout);
 431
 432 /*
 433  * Waitqueues which are removed from the waitqueue_head at wakeup time
 434  */
 435 void prepare_to_wait(wait_queue_head_t *q, wait_queue_t *wait, int state);
 436 void prepare_to_wait_exclusive(wait_queue_head_t *q, wait_queue_t *wait, int state);
 437 void finish_wait(wait_queue_head_t *q, wait_queue_t *wait);
 438 void abort_exclusive_wait(wait_queue_head_t *q, wait_queue_t *wait,
 439                         unsigned int mode, void *key);
 440 int autoremove_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 441 int wake_bit_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 442
 443 #define DEFINE_WAIT_FUNC(name, function)                                \
 444         wait_queue_t name = {                                           \
 445                 .private        = current,                              \
 446                 .func           = function,                             \
 447                 .task_list      = LIST_HEAD_INIT((name).task_list),     \
 448         }
 449
 450 #define DEFINE_WAIT(name) DEFINE_WAIT_FUNC(name, autoremove_wake_function)
 451
 452 #define DEFINE_WAIT_BIT(name, word, bit)                                \
 453         struct wait_bit_queue name = {                                  \
 454                 .key = __WAIT_BIT_KEY_INITIALIZER(word, bit),           \
 455                 .wait   = {                                             \
 456                         .private        = current,                      \
 457                         .func           = wake_bit_function,            \
 458                         .task_list      =                               \
 459                                 LIST_HEAD_INIT((name).wait.task_list),  \
 460                 },                                                      \
 461         }
 462
 463 #define init_wait(wait)                                                 \
 464         do {                                                            \
 465                 (wait)->private = current;                              \
 466                 (wait)->func = autoremove_wake_function;                \
 467                 INIT_LIST_HEAD(&(wait)->task_list);                     \
 468         } while (0)
 469
 470 /**
 471  * wait_on_bit - wait for a bit to be cleared
 472  * @word: the word being waited on, a kernel virtual address
 473  * @bit: the bit of the word being waited on
 474  * @action: the function used to sleep, which may take special actions
 475  * @mode: the task state to sleep in
 476  *
 477  * There is a standard hashed waitqueue table for generic use. This
 478  * is the part of the hashtable's accessor API that waits on a bit.
 479  * For instance, if one were to have waiters on a bitflag, one would
 480  * call wait_on_bit() in threads waiting for the bit to clear.
 481  * One uses wait_on_bit() where one is waiting for the bit to clear,
 482  * but has no intention of setting it.
 483  */
 484 static inline int wait_on_bit(void *word, int bit,
 485                                 int (*action)(void *), unsigned mode)
 486 {
 487         if (!test_bit(bit, word))
 488                 return 0;
 489         return out_of_line_wait_on_bit(word, bit, action, mode);
 490 }
 491
 492 /**
 493  * wait_on_bit_lock - wait for a bit to be cleared, when wanting to set it
 494  * @word: the word being waited on, a kernel virtual address
 495  * @bit: the bit of the word being waited on
 496  * @action: the function used to sleep, which may take special actions
 497  * @mode: the task state to sleep in
 498  *
 499  * There is a standard hashed waitqueue table for generic use. This
 500  * is the part of the hashtable's accessor API that waits on a bit
 501  * when one intends to set it, for instance, trying to lock bitflags.
 502  * For instance, if one were to have waiters trying to set bitflag
 503  * and waiting for it to clear before setting it, one would call
 504  * wait_on_bit() in threads waiting to be able to set the bit.
 505  * One uses wait_on_bit_lock() where one is waiting for the bit to
 506  * clear with the intention of setting it, and when done, clearing it.
 507  */
 508 static inline int wait_on_bit_lock(void *word, int bit,
 509                                 int (*action)(void *), unsigned mode)
 510 {
 511         if (!test_and_set_bit(bit, word))
 512                 return 0;
 513         return out_of_line_wait_on_bit_lock(word, bit, action, mode);
 514 }
 515
 516 #endif /* __KERNEL__ */
 517
 518 #endif