include/linux/wait.h

   1 #ifndef _LINUX_WAIT_H
   2 #define _LINUX_WAIT_H
   3
   4
   5 #include <linux/list.h>
   6 #include <linux/stddef.h>
   7 #include <linux/spinlock.h>
   8 #include <asm/current.h>
   9 #include <uapi/linux/wait.h>
  10
  11 typedef struct __wait_queue wait_queue_t;
  12 typedef int (*wait_queue_func_t)(wait_queue_t *wait, unsigned mode, int flags, void *key);
  13 int default_wake_function(wait_queue_t *wait, unsigned mode, int flags, void *key);
  14
  15 struct __wait_queue {
  16         unsigned int flags;
  17 #define WQ_FLAG_EXCLUSIVE       0x01
  18         void *private;
  19         wait_queue_func_t func;
  20         struct list_head task_list;
  21 };
  22
  23 struct wait_bit_key {
  24         void *flags;
  25         int bit_nr;
  26 #define WAIT_ATOMIC_T_BIT_NR -1
  27 };
  28
  29 struct wait_bit_queue {
  30         struct wait_bit_key key;
  31         wait_queue_t wait;
  32 };
  33
  34 struct __wait_queue_head {
  35         spinlock_t lock;
  36         struct list_head task_list;
  37 };
  38 typedef struct __wait_queue_head wait_queue_head_t;
  39
  40 struct task_struct;
  41
  42 /*
  43  * Macros for declaration and initialisaton of the datatypes
  44  */
  45
  46 #define __WAITQUEUE_INITIALIZER(name, tsk) {                            \
  47         .private        = tsk,                                          \
  48         .func           = default_wake_function,                        \
  49         .task_list      = { NULL, NULL } }
  50
  51 #define DECLARE_WAITQUEUE(name, tsk)                                    \
  52         wait_queue_t name = __WAITQUEUE_INITIALIZER(name, tsk)
  53
  54 #define __WAIT_QUEUE_HEAD_INITIALIZER(name) {                           \
  55         .lock           = __SPIN_LOCK_UNLOCKED(name.lock),              \
  56         .task_list      = { &(name).task_list, &(name).task_list } }
  57
  58 #define DECLARE_WAIT_QUEUE_HEAD(name) \
  59         wait_queue_head_t name = __WAIT_QUEUE_HEAD_INITIALIZER(name)
  60
  61 #define __WAIT_BIT_KEY_INITIALIZER(word, bit)                           \
  62         { .flags = word, .bit_nr = bit, }
  63
  64 #define __WAIT_ATOMIC_T_KEY_INITIALIZER(p)                              \
  65         { .flags = p, .bit_nr = WAIT_ATOMIC_T_BIT_NR, }
  66
  67 extern void __init_waitqueue_head(wait_queue_head_t *q, const char *name, struct lock_class_key *);
  68
  69 #define init_waitqueue_head(q)                          \
  70         do {                                            \
  71                 static struct lock_class_key __key;     \
  72                                                         \
  73                 __init_waitqueue_head((q), #q, &__key); \
  74         } while (0)
  75
  76 #ifdef CONFIG_LOCKDEP
  77 # define __WAIT_QUEUE_HEAD_INIT_ONSTACK(name) \
  78         ({ init_waitqueue_head(&name); name; })
  79 # define DECLARE_WAIT_QUEUE_HEAD_ONSTACK(name) \
  80         wait_queue_head_t name = __WAIT_QUEUE_HEAD_INIT_ONSTACK(name)
  81 #else
  82 # define DECLARE_WAIT_QUEUE_HEAD_ONSTACK(name) DECLARE_WAIT_QUEUE_HEAD(name)
  83 #endif
  84
  85 static inline void init_waitqueue_entry(wait_queue_t *q, struct task_struct *p)
  86 {
  87         q->flags = 0;
  88         q->private = p;
  89         q->func = default_wake_function;
  90 }
  91
  92 static inline void init_waitqueue_func_entry(wait_queue_t *q,
  93                                         wait_queue_func_t func)
  94 {
  95         q->flags = 0;
  96         q->private = NULL;
  97         q->func = func;
  98 }
  99
 100 static inline int waitqueue_active(wait_queue_head_t *q)
 101 {
 102         return !list_empty(&q->task_list);
 103 }
 104
 105 extern void add_wait_queue(wait_queue_head_t *q, wait_queue_t *wait);
 106 extern void add_wait_queue_exclusive(wait_queue_head_t *q, wait_queue_t *wait);
 107 extern void remove_wait_queue(wait_queue_head_t *q, wait_queue_t *wait);
 108
 109 static inline void __add_wait_queue(wait_queue_head_t *head, wait_queue_t *new)
 110 {
 111         list_add(&new->task_list, &head->task_list);
 112 }
 113
 114 /*
 115  * Used for wake-one threads:
 116  */
 117 static inline void __add_wait_queue_exclusive(wait_queue_head_t *q,
 118                                               wait_queue_t *wait)
 119 {
 120         wait->flags |= WQ_FLAG_EXCLUSIVE;
 121         __add_wait_queue(q, wait);
 122 }
 123
 124 static inline void __add_wait_queue_tail(wait_queue_head_t *head,
 125                                          wait_queue_t *new)
 126 {
 127         list_add_tail(&new->task_list, &head->task_list);
 128 }
 129
 130 static inline void __add_wait_queue_tail_exclusive(wait_queue_head_t *q,
 131                                               wait_queue_t *wait)
 132 {
 133         wait->flags |= WQ_FLAG_EXCLUSIVE;
 134         __add_wait_queue_tail(q, wait);
 135 }
 136
 137 static inline void __remove_wait_queue(wait_queue_head_t *head,
 138                                                         wait_queue_t *old)
 139 {
 140         list_del(&old->task_list);
 141 }
 142
 143 void __wake_up(wait_queue_head_t *q, unsigned int mode, int nr, void *key);
 144 void __wake_up_locked_key(wait_queue_head_t *q, unsigned int mode, void *key);
 145 void __wake_up_sync_key(wait_queue_head_t *q, unsigned int mode, int nr,
 146                         void *key);
 147 void __wake_up_locked(wait_queue_head_t *q, unsigned int mode, int nr);
 148 void __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr);
 149 void __wake_up_bit(wait_queue_head_t *, void *, int);
 150 int __wait_on_bit(wait_queue_head_t *, struct wait_bit_queue *, int (*)(void *), unsigned);
 151 int __wait_on_bit_lock(wait_queue_head_t *, struct wait_bit_queue *, int (*)(void *), unsigned);
 152 void wake_up_bit(void *, int);
 153 void wake_up_atomic_t(atomic_t *);
 154 int out_of_line_wait_on_bit(void *, int, int (*)(void *), unsigned);
 155 int out_of_line_wait_on_bit_lock(void *, int, int (*)(void *), unsigned);
 156 int out_of_line_wait_on_atomic_t(atomic_t *, int (*)(atomic_t *), unsigned);
 157 wait_queue_head_t *bit_waitqueue(void *, int);
 158
 159 #define wake_up(x)                      __wake_up(x, TASK_NORMAL, 1, NULL)
 160 #define wake_up_nr(x, nr)               __wake_up(x, TASK_NORMAL, nr, NULL)
 161 #define wake_up_all(x)                  __wake_up(x, TASK_NORMAL, 0, NULL)
 162 #define wake_up_locked(x)               __wake_up_locked((x), TASK_NORMAL, 1)
 163 #define wake_up_all_locked(x)           __wake_up_locked((x), TASK_NORMAL, 0)
 164
 165 #define wake_up_interruptible(x)        __wake_up(x, TASK_INTERRUPTIBLE, 1, NULL)
 166 #define wake_up_interruptible_nr(x, nr) __wake_up(x, TASK_INTERRUPTIBLE, nr, NULL)
 167 #define wake_up_interruptible_all(x)    __wake_up(x, TASK_INTERRUPTIBLE, 0, NULL)
 168 #define wake_up_interruptible_sync(x)   __wake_up_sync((x), TASK_INTERRUPTIBLE, 1)
 169
 170 /*
 171  * Wakeup macros to be used to report events to the targets.
 172  */
 173 #define wake_up_poll(x, m)                              \
 174         __wake_up(x, TASK_NORMAL, 1, (void *) (m))
 175 #define wake_up_locked_poll(x, m)                               \
 176         __wake_up_locked_key((x), TASK_NORMAL, (void *) (m))
 177 #define wake_up_interruptible_poll(x, m)                        \
 178         __wake_up(x, TASK_INTERRUPTIBLE, 1, (void *) (m))
 179 #define wake_up_interruptible_sync_poll(x, m)                           \
 180         __wake_up_sync_key((x), TASK_INTERRUPTIBLE, 1, (void *) (m))
 181
 182 #define __wait_event(wq, condition)                                     \
 183 do {                                                                    \
 184         DEFINE_WAIT(__wait);                                            \
 185                                                                         \
 186         for (;;) {                                                      \
 187                 prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE);    \
 188                 if (condition)                                          \
 189                         break;                                          \
 190                 schedule();                                             \
 191         }                                                               \
 192         finish_wait(&wq, &__wait);                                      \
 193 } while (0)
 194
 195 /**
 196  * wait_event - sleep until a condition gets true
 197  * @wq: the waitqueue to wait on
 198  * @condition: a C expression for the event to wait for
 199  *
 200  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 201  * @condition evaluates to true. The @condition is checked each time
 202  * the waitqueue @wq is woken up.
 203  *
 204  * wake_up() has to be called after changing any variable that could
 205  * change the result of the wait condition.
 206  */
 207 #define wait_event(wq, condition)                                       \
 208 do {                                                                    \
 209         if (condition)                                                  \
 210                 break;                                                  \
 211         __wait_event(wq, condition);                                    \
 212 } while (0)
 213
 214 #define __wait_event_timeout(wq, condition, ret)                        \
 215 do {                                                                    \
 216         DEFINE_WAIT(__wait);                                            \
 217                                                                         \
 218         for (;;) {                                                      \
 219                 prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE);    \
 220                 if (condition)                                          \
 221                         break;                                          \
 222                 ret = schedule_timeout(ret);                            \
 223                 if (!ret)                                               \
 224                         break;                                          \
 225         }                                                               \
 226         if (!ret && (condition))                                        \
 227                 ret = 1;                                                \
 228         finish_wait(&wq, &__wait);                                      \
 229 } while (0)
 230
 231 /**
 232  * wait_event_timeout - sleep until a condition gets true or a timeout elapses
 233  * @wq: the waitqueue to wait on
 234  * @condition: a C expression for the event to wait for
 235  * @timeout: timeout, in jiffies
 236  *
 237  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 238  * @condition evaluates to true. The @condition is checked each time
 239  * the waitqueue @wq is woken up.
 240  *
 241  * wake_up() has to be called after changing any variable that could
 242  * change the result of the wait condition.
 243  *
 244  * The function returns 0 if the @timeout elapsed, or the remaining
 245  * jiffies (at least 1) if the @condition evaluated to %true before
 246  * the @timeout elapsed.
 247  */
 248 #define wait_event_timeout(wq, condition, timeout)                      \
 249 ({                                                                      \
 250         long __ret = timeout;                                           \
 251         if (!(condition))                                               \
 252                 __wait_event_timeout(wq, condition, __ret);             \
 253         __ret;                                                          \
 254 })
 255
 256 #define __wait_event_interruptible(wq, condition, ret)                  \
 257 do {                                                                    \
 258         DEFINE_WAIT(__wait);                                            \
 259                                                                         \
 260         for (;;) {                                                      \
 261                 prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE);      \
 262                 if (condition)                                          \
 263                         break;                                          \
 264                 if (!signal_pending(current)) {                         \
 265                         schedule();                                     \
 266                         continue;                                       \
 267                 }                                                       \
 268                 ret = -ERESTARTSYS;                                     \
 269                 break;                                                  \
 270         }                                                               \
 271         finish_wait(&wq, &__wait);                                      \
 272 } while (0)
 273
 274 /**
 275  * wait_event_interruptible - sleep until a condition gets true
 276  * @wq: the waitqueue to wait on
 277  * @condition: a C expression for the event to wait for
 278  *
 279  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 280  * @condition evaluates to true or a signal is received.
 281  * The @condition is checked each time the waitqueue @wq is woken up.
 282  *
 283  * wake_up() has to be called after changing any variable that could
 284  * change the result of the wait condition.
 285  *
 286  * The function will return -ERESTARTSYS if it was interrupted by a
 287  * signal and 0 if @condition evaluated to true.
 288  */
 289 #define wait_event_interruptible(wq, condition)                         \
 290 ({                                                                      \
 291         int __ret = 0;                                                  \
 292         if (!(condition))                                               \
 293                 __wait_event_interruptible(wq, condition, __ret);       \
 294         __ret;                                                          \
 295 })
 296
 297 #define __wait_event_interruptible_timeout(wq, condition, ret)          \
 298 do {                                                                    \
 299         DEFINE_WAIT(__wait);                                            \
 300                                                                         \
 301         for (;;) {                                                      \
 302                 prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE);      \
 303                 if (condition)                                          \
 304                         break;                                          \
 305                 if (!signal_pending(current)) {                         \
 306                         ret = schedule_timeout(ret);                    \
 307                         if (!ret)                                       \
 308                                 break;                                  \
 309                         continue;                                       \
 310                 }                                                       \
 311                 ret = -ERESTARTSYS;                                     \
 312                 break;                                                  \
 313         }                                                               \
 314         if (!ret && (condition))                                        \
 315                 ret = 1;                                                \
 316         finish_wait(&wq, &__wait);                                      \
 317 } while (0)
 318
 319 /**
 320  * wait_event_interruptible_timeout - sleep until a condition gets true or a timeout elapses
 321  * @wq: the waitqueue to wait on
 322  * @condition: a C expression for the event to wait for
 323  * @timeout: timeout, in jiffies
 324  *
 325  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 326  * @condition evaluates to true or a signal is received.
 327  * The @condition is checked each time the waitqueue @wq is woken up.
 328  *
 329  * wake_up() has to be called after changing any variable that could
 330  * change the result of the wait condition.
 331  *
 332  * Returns:
 333  * 0 if the @timeout elapsed, -%ERESTARTSYS if it was interrupted by
 334  * a signal, or the remaining jiffies (at least 1) if the @condition
 335  * evaluated to %true before the @timeout elapsed.
 336  */
 337 #define wait_event_interruptible_timeout(wq, condition, timeout)        \
 338 ({                                                                      \
 339         long __ret = timeout;                                           \
 340         if (!(condition))                                               \
 341                 __wait_event_interruptible_timeout(wq, condition, __ret); \
 342         __ret;                                                          \
 343 })
 344
 345 #define __wait_event_hrtimeout(wq, condition, timeout, state)           \
 346 ({                                                                      \
 347         int __ret = 0;                                                  \
 348         DEFINE_WAIT(__wait);                                            \
 349         struct hrtimer_sleeper __t;                                     \
 350                                                                         \
 351         hrtimer_init_on_stack(&__t.timer, CLOCK_MONOTONIC,              \
 352                               HRTIMER_MODE_REL);                        \
 353         hrtimer_init_sleeper(&__t, current);                            \
 354         if ((timeout).tv64 != KTIME_MAX)                                \
 355                 hrtimer_start_range_ns(&__t.timer, timeout,             \
 356                                        current->timer_slack_ns,         \
 357                                        HRTIMER_MODE_REL);               \
 358                                                                         \
 359         for (;;) {                                                      \
 360                 prepare_to_wait(&wq, &__wait, state);                   \
 361                 if (condition)                                          \
 362                         break;                                          \
 363                 if (state == TASK_INTERRUPTIBLE &&                      \
 364                     signal_pending(current)) {                          \
 365                         __ret = -ERESTARTSYS;                           \
 366                         break;                                          \
 367                 }                                                       \
 368                 if (!__t.task) {                                        \
 369                         __ret = -ETIME;                                 \
 370                         break;                                          \
 371                 }                                                       \
 372                 schedule();                                             \
 373         }                                                               \
 374                                                                         \
 375         hrtimer_cancel(&__t.timer);                                     \
 376         destroy_hrtimer_on_stack(&__t.timer);                           \
 377         finish_wait(&wq, &__wait);                                      \
 378         __ret;                                                          \
 379 })
 380
 381 /**
 382  * wait_event_hrtimeout - sleep until a condition gets true or a timeout elapses
 383  * @wq: the waitqueue to wait on
 384  * @condition: a C expression for the event to wait for
 385  * @timeout: timeout, as a ktime_t
 386  *
 387  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 388  * @condition evaluates to true or a signal is received.
 389  * The @condition is checked each time the waitqueue @wq is woken up.
 390  *
 391  * wake_up() has to be called after changing any variable that could
 392  * change the result of the wait condition.
 393  *
 394  * The function returns 0 if @condition became true, or -ETIME if the timeout
 395  * elapsed.
 396  */
 397 #define wait_event_hrtimeout(wq, condition, timeout)                    \
 398 ({                                                                      \
 399         int __ret = 0;                                                  \
 400         if (!(condition))                                               \
 401                 __ret = __wait_event_hrtimeout(wq, condition, timeout,  \
 402                                                TASK_UNINTERRUPTIBLE);   \
 403         __ret;                                                          \
 404 })
 405
 406 /**
 407  * wait_event_interruptible_hrtimeout - sleep until a condition gets true or a timeout elapses
 408  * @wq: the waitqueue to wait on
 409  * @condition: a C expression for the event to wait for
 410  * @timeout: timeout, as a ktime_t
 411  *
 412  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 413  * @condition evaluates to true or a signal is received.
 414  * The @condition is checked each time the waitqueue @wq is woken up.
 415  *
 416  * wake_up() has to be called after changing any variable that could
 417  * change the result of the wait condition.
 418  *
 419  * The function returns 0 if @condition became true, -ERESTARTSYS if it was
 420  * interrupted by a signal, or -ETIME if the timeout elapsed.
 421  */
 422 #define wait_event_interruptible_hrtimeout(wq, condition, timeout)      \
 423 ({                                                                      \
 424         long __ret = 0;                                                 \
 425         if (!(condition))                                               \
 426                 __ret = __wait_event_hrtimeout(wq, condition, timeout,  \
 427                                                TASK_INTERRUPTIBLE);     \
 428         __ret;                                                          \
 429 })
 430
 431 #define __wait_event_interruptible_exclusive(wq, condition, ret)        \
 432 do {                                                                    \
 433         DEFINE_WAIT(__wait);                                            \
 434                                                                         \
 435         for (;;) {                                                      \
 436                 prepare_to_wait_exclusive(&wq, &__wait,                 \
 437                                         TASK_INTERRUPTIBLE);            \
 438                 if (condition) {                                        \
 439                         finish_wait(&wq, &__wait);                      \
 440                         break;                                          \
 441                 }                                                       \
 442                 if (!signal_pending(current)) {                         \
 443                         schedule();                                     \
 444                         continue;                                       \
 445                 }                                                       \
 446                 ret = -ERESTARTSYS;                                     \
 447                 abort_exclusive_wait(&wq, &__wait,                      \
 448                                 TASK_INTERRUPTIBLE, NULL);              \
 449                 break;                                                  \
 450         }                                                               \
 451 } while (0)
 452
 453 #define wait_event_interruptible_exclusive(wq, condition)               \
 454 ({                                                                      \
 455         int __ret = 0;                                                  \
 456         if (!(condition))                                               \
 457                 __wait_event_interruptible_exclusive(wq, condition, __ret);\
 458         __ret;                                                          \
 459 })
 460
 461
 462 #define __wait_event_interruptible_locked(wq, condition, exclusive, irq) \
 463 ({                                                                      \
 464         int __ret = 0;                                                  \
 465         DEFINE_WAIT(__wait);                                            \
 466         if (exclusive)                                                  \
 467                 __wait.flags |= WQ_FLAG_EXCLUSIVE;                      \
 468         do {                                                            \
 469                 if (likely(list_empty(&__wait.task_list)))              \
 470                         __add_wait_queue_tail(&(wq), &__wait);          \
 471                 set_current_state(TASK_INTERRUPTIBLE);                  \
 472                 if (signal_pending(current)) {                          \
 473                         __ret = -ERESTARTSYS;                           \
 474                         break;                                          \
 475                 }                                                       \
 476                 if (irq)                                                \
 477                         spin_unlock_irq(&(wq).lock);                    \
 478                 else                                                    \
 479                         spin_unlock(&(wq).lock);                        \
 480                 schedule();                                             \
 481                 if (irq)                                                \
 482                         spin_lock_irq(&(wq).lock);                      \
 483                 else                                                    \
 484                         spin_lock(&(wq).lock);                          \
 485         } while (!(condition));                                         \
 486         __remove_wait_queue(&(wq), &__wait);                            \
 487         __set_current_state(TASK_RUNNING);                              \
 488         __ret;                                                          \
 489 })
 490
 491
 492 /**
 493  * wait_event_interruptible_locked - sleep until a condition gets true
 494  * @wq: the waitqueue to wait on
 495  * @condition: a C expression for the event to wait for
 496  *
 497  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 498  * @condition evaluates to true or a signal is received.
 499  * The @condition is checked each time the waitqueue @wq is woken up.
 500  *
 501  * It must be called with wq.lock being held.  This spinlock is
 502  * unlocked while sleeping but @condition testing is done while lock
 503  * is held and when this macro exits the lock is held.
 504  *
 505  * The lock is locked/unlocked using spin_lock()/spin_unlock()
 506  * functions which must match the way they are locked/unlocked outside
 507  * of this macro.
 508  *
 509  * wake_up_locked() has to be called after changing any variable that could
 510  * change the result of the wait condition.
 511  *
 512  * The function will return -ERESTARTSYS if it was interrupted by a
 513  * signal and 0 if @condition evaluated to true.
 514  */
 515 #define wait_event_interruptible_locked(wq, condition)                  \
 516         ((condition)                                                    \
 517          ? 0 : __wait_event_interruptible_locked(wq, condition, 0, 0))
 518
 519 /**
 520  * wait_event_interruptible_locked_irq - sleep until a condition gets true
 521  * @wq: the waitqueue to wait on
 522  * @condition: a C expression for the event to wait for
 523  *
 524  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 525  * @condition evaluates to true or a signal is received.
 526  * The @condition is checked each time the waitqueue @wq is woken up.
 527  *
 528  * It must be called with wq.lock being held.  This spinlock is
 529  * unlocked while sleeping but @condition testing is done while lock
 530  * is held and when this macro exits the lock is held.
 531  *
 532  * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq()
 533  * functions which must match the way they are locked/unlocked outside
 534  * of this macro.
 535  *
 536  * wake_up_locked() has to be called after changing any variable that could
 537  * change the result of the wait condition.
 538  *
 539  * The function will return -ERESTARTSYS if it was interrupted by a
 540  * signal and 0 if @condition evaluated to true.
 541  */
 542 #define wait_event_interruptible_locked_irq(wq, condition)              \
 543         ((condition)                                                    \
 544          ? 0 : __wait_event_interruptible_locked(wq, condition, 0, 1))
 545
 546 /**
 547  * wait_event_interruptible_exclusive_locked - sleep exclusively until a condition gets true
 548  * @wq: the waitqueue to wait on
 549  * @condition: a C expression for the event to wait for
 550  *
 551  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 552  * @condition evaluates to true or a signal is received.
 553  * The @condition is checked each time the waitqueue @wq is woken up.
 554  *
 555  * It must be called with wq.lock being held.  This spinlock is
 556  * unlocked while sleeping but @condition testing is done while lock
 557  * is held and when this macro exits the lock is held.
 558  *
 559  * The lock is locked/unlocked using spin_lock()/spin_unlock()
 560  * functions which must match the way they are locked/unlocked outside
 561  * of this macro.
 562  *
 563  * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
 564  * set thus when other process waits process on the list if this
 565  * process is awaken further processes are not considered.
 566  *
 567  * wake_up_locked() has to be called after changing any variable that could
 568  * change the result of the wait condition.
 569  *
 570  * The function will return -ERESTARTSYS if it was interrupted by a
 571  * signal and 0 if @condition evaluated to true.
 572  */
 573 #define wait_event_interruptible_exclusive_locked(wq, condition)        \
 574         ((condition)                                                    \
 575          ? 0 : __wait_event_interruptible_locked(wq, condition, 1, 0))
 576
 577 /**
 578  * wait_event_interruptible_exclusive_locked_irq - sleep until a condition gets true
 579  * @wq: the waitqueue to wait on
 580  * @condition: a C expression for the event to wait for
 581  *
 582  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 583  * @condition evaluates to true or a signal is received.
 584  * The @condition is checked each time the waitqueue @wq is woken up.
 585  *
 586  * It must be called with wq.lock being held.  This spinlock is
 587  * unlocked while sleeping but @condition testing is done while lock
 588  * is held and when this macro exits the lock is held.
 589  *
 590  * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq()
 591  * functions which must match the way they are locked/unlocked outside
 592  * of this macro.
 593  *
 594  * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
 595  * set thus when other process waits process on the list if this
 596  * process is awaken further processes are not considered.
 597  *
 598  * wake_up_locked() has to be called after changing any variable that could
 599  * change the result of the wait condition.
 600  *
 601  * The function will return -ERESTARTSYS if it was interrupted by a
 602  * signal and 0 if @condition evaluated to true.
 603  */
 604 #define wait_event_interruptible_exclusive_locked_irq(wq, condition)    \
 605         ((condition)                                                    \
 606          ? 0 : __wait_event_interruptible_locked(wq, condition, 1, 1))
 607
 608
 609
 610 #define __wait_event_killable(wq, condition, ret)                       \
 611 do {                                                                    \
 612         DEFINE_WAIT(__wait);                                            \
 613                                                                         \
 614         for (;;) {                                                      \
 615                 prepare_to_wait(&wq, &__wait, TASK_KILLABLE);           \
 616                 if (condition)                                          \
 617                         break;                                          \
 618                 if (!fatal_signal_pending(current)) {                   \
 619                         schedule();                                     \
 620                         continue;                                       \
 621                 }                                                       \
 622                 ret = -ERESTARTSYS;                                     \
 623                 break;                                                  \
 624         }                                                               \
 625         finish_wait(&wq, &__wait);                                      \
 626 } while (0)
 627
 628 /**
 629  * wait_event_killable - sleep until a condition gets true
 630  * @wq: the waitqueue to wait on
 631  * @condition: a C expression for the event to wait for
 632  *
 633  * The process is put to sleep (TASK_KILLABLE) until the
 634  * @condition evaluates to true or a signal is received.
 635  * The @condition is checked each time the waitqueue @wq is woken up.
 636  *
 637  * wake_up() has to be called after changing any variable that could
 638  * change the result of the wait condition.
 639  *
 640  * The function will return -ERESTARTSYS if it was interrupted by a
 641  * signal and 0 if @condition evaluated to true.
 642  */
 643 #define wait_event_killable(wq, condition)                              \
 644 ({                                                                      \
 645         int __ret = 0;                                                  \
 646         if (!(condition))                                               \
 647                 __wait_event_killable(wq, condition, __ret);            \
 648         __ret;                                                          \
 649 })
 650
 651
 652 #define __wait_event_lock_irq(wq, condition, lock, cmd)                 \
 653 do {                                                                    \
 654         DEFINE_WAIT(__wait);                                            \
 655                                                                         \
 656         for (;;) {                                                      \
 657                 prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE);    \
 658                 if (condition)                                          \
 659                         break;                                          \
 660                 spin_unlock_irq(&lock);                                 \
 661                 cmd;                                                    \
 662                 schedule();                                             \
 663                 spin_lock_irq(&lock);                                   \
 664         }                                                               \
 665         finish_wait(&wq, &__wait);                                      \
 666 } while (0)
 667
 668 /**
 669  * wait_event_lock_irq_cmd - sleep until a condition gets true. The
 670  *                           condition is checked under the lock. This
 671  *                           is expected to be called with the lock
 672  *                           taken.
 673  * @wq: the waitqueue to wait on
 674  * @condition: a C expression for the event to wait for
 675  * @lock: a locked spinlock_t, which will be released before cmd
 676  *        and schedule() and reacquired afterwards.
 677  * @cmd: a command which is invoked outside the critical section before
 678  *       sleep
 679  *
 680  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 681  * @condition evaluates to true. The @condition is checked each time
 682  * the waitqueue @wq is woken up.
 683  *
 684  * wake_up() has to be called after changing any variable that could
 685  * change the result of the wait condition.
 686  *
 687  * This is supposed to be called while holding the lock. The lock is
 688  * dropped before invoking the cmd and going to sleep and is reacquired
 689  * afterwards.
 690  */
 691 #define wait_event_lock_irq_cmd(wq, condition, lock, cmd)               \
 692 do {                                                                    \
 693         if (condition)                                                  \
 694                 break;                                                  \
 695         __wait_event_lock_irq(wq, condition, lock, cmd);                \
 696 } while (0)
 697
 698 /**
 699  * wait_event_lock_irq - sleep until a condition gets true. The
 700  *                       condition is checked under the lock. This
 701  *                       is expected to be called with the lock
 702  *                       taken.
 703  * @wq: the waitqueue to wait on
 704  * @condition: a C expression for the event to wait for
 705  * @lock: a locked spinlock_t, which will be released before schedule()
 706  *        and reacquired afterwards.
 707  *
 708  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 709  * @condition evaluates to true. The @condition is checked each time
 710  * the waitqueue @wq is woken up.
 711  *
 712  * wake_up() has to be called after changing any variable that could
 713  * change the result of the wait condition.
 714  *
 715  * This is supposed to be called while holding the lock. The lock is
 716  * dropped before going to sleep and is reacquired afterwards.
 717  */
 718 #define wait_event_lock_irq(wq, condition, lock)                        \
 719 do {                                                                    \
 720         if (condition)                                                  \
 721                 break;                                                  \
 722         __wait_event_lock_irq(wq, condition, lock, );                   \
 723 } while (0)
 724
 725
 726 #define __wait_event_interruptible_lock_irq(wq, condition,              \
 727                                             lock, ret, cmd)             \
 728 do {                                                                    \
 729         DEFINE_WAIT(__wait);                                            \
 730                                                                         \
 731         for (;;) {                                                      \
 732                 prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE);      \
 733                 if (condition)                                          \
 734                         break;                                          \
 735                 if (signal_pending(current)) {                          \
 736                         ret = -ERESTARTSYS;                             \
 737                         break;                                          \
 738                 }                                                       \
 739                 spin_unlock_irq(&lock);                                 \
 740                 cmd;                                                    \
 741                 schedule();                                             \
 742                 spin_lock_irq(&lock);                                   \
 743         }                                                               \
 744         finish_wait(&wq, &__wait);                                      \
 745 } while (0)
 746
 747 /**
 748  * wait_event_interruptible_lock_irq_cmd - sleep until a condition gets true.
 749  *              The condition is checked under the lock. This is expected to
 750  *              be called with the lock taken.
 751  * @wq: the waitqueue to wait on
 752  * @condition: a C expression for the event to wait for
 753  * @lock: a locked spinlock_t, which will be released before cmd and
 754  *        schedule() and reacquired afterwards.
 755  * @cmd: a command which is invoked outside the critical section before
 756  *       sleep
 757  *
 758  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 759  * @condition evaluates to true or a signal is received. The @condition is
 760  * checked each time the waitqueue @wq is woken up.
 761  *
 762  * wake_up() has to be called after changing any variable that could
 763  * change the result of the wait condition.
 764  *
 765  * This is supposed to be called while holding the lock. The lock is
 766  * dropped before invoking the cmd and going to sleep and is reacquired
 767  * afterwards.
 768  *
 769  * The macro will return -ERESTARTSYS if it was interrupted by a signal
 770  * and 0 if @condition evaluated to true.
 771  */
 772 #define wait_event_interruptible_lock_irq_cmd(wq, condition, lock, cmd) \
 773 ({                                                                      \
 774         int __ret = 0;                                                  \
 775                                                                         \
 776         if (!(condition))                                               \
 777                 __wait_event_interruptible_lock_irq(wq, condition,      \
 778                                                     lock, __ret, cmd);  \
 779         __ret;                                                          \
 780 })
 781
 782 /**
 783  * wait_event_interruptible_lock_irq - sleep until a condition gets true.
 784  *              The condition is checked under the lock. This is expected
 785  *              to be called with the lock taken.
 786  * @wq: the waitqueue to wait on
 787  * @condition: a C expression for the event to wait for
 788  * @lock: a locked spinlock_t, which will be released before schedule()
 789  *        and reacquired afterwards.
 790  *
 791  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 792  * @condition evaluates to true or signal is received. The @condition is
 793  * checked each time the waitqueue @wq is woken up.
 794  *
 795  * wake_up() has to be called after changing any variable that could
 796  * change the result of the wait condition.
 797  *
 798  * This is supposed to be called while holding the lock. The lock is
 799  * dropped before going to sleep and is reacquired afterwards.
 800  *
 801  * The macro will return -ERESTARTSYS if it was interrupted by a signal
 802  * and 0 if @condition evaluated to true.
 803  */
 804 #define wait_event_interruptible_lock_irq(wq, condition, lock)          \
 805 ({                                                                      \
 806         int __ret = 0;                                                  \
 807                                                                         \
 808         if (!(condition))                                               \
 809                 __wait_event_interruptible_lock_irq(wq, condition,      \
 810                                                     lock, __ret, );     \
 811         __ret;                                                          \
 812 })
 813
 814
 815 /*
 816  * These are the old interfaces to sleep waiting for an event.
 817  * They are racy.  DO NOT use them, use the wait_event* interfaces above.
 818  * We plan to remove these interfaces.
 819  */
 820 extern void sleep_on(wait_queue_head_t *q);
 821 extern long sleep_on_timeout(wait_queue_head_t *q,
 822                                       signed long timeout);
 823 extern void interruptible_sleep_on(wait_queue_head_t *q);
 824 extern long interruptible_sleep_on_timeout(wait_queue_head_t *q,
 825                                            signed long timeout);
 826
 827 /*
 828  * Waitqueues which are removed from the waitqueue_head at wakeup time
 829  */
 830 void prepare_to_wait(wait_queue_head_t *q, wait_queue_t *wait, int state);
 831 void prepare_to_wait_exclusive(wait_queue_head_t *q, wait_queue_t *wait, int state);
 832 void finish_wait(wait_queue_head_t *q, wait_queue_t *wait);
 833 void abort_exclusive_wait(wait_queue_head_t *q, wait_queue_t *wait,
 834                         unsigned int mode, void *key);
 835 int autoremove_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 836 int wake_bit_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 837
 838 #define DEFINE_WAIT_FUNC(name, function)                                \
 839         wait_queue_t name = {                                           \
 840                 .private        = current,                              \
 841                 .func           = function,                             \
 842                 .task_list      = LIST_HEAD_INIT((name).task_list),     \
 843         }
 844
 845 #define DEFINE_WAIT(name) DEFINE_WAIT_FUNC(name, autoremove_wake_function)
 846
 847 #define DEFINE_WAIT_BIT(name, word, bit)                                \
 848         struct wait_bit_queue name = {                                  \
 849                 .key = __WAIT_BIT_KEY_INITIALIZER(word, bit),           \
 850                 .wait   = {                                             \
 851                         .private        = current,                      \
 852                         .func           = wake_bit_function,            \
 853                         .task_list      =                               \
 854                                 LIST_HEAD_INIT((name).wait.task_list),  \
 855                 },                                                      \
 856         }
 857
 858 #define init_wait(wait)                                                 \
 859         do {                                                            \
 860                 (wait)->private = current;                              \
 861                 (wait)->func = autoremove_wake_function;                \
 862                 INIT_LIST_HEAD(&(wait)->task_list);                     \
 863                 (wait)->flags = 0;                                      \
 864         } while (0)
 865
 866 /**
 867  * wait_on_bit - wait for a bit to be cleared
 868  * @word: the word being waited on, a kernel virtual address
 869  * @bit: the bit of the word being waited on
 870  * @action: the function used to sleep, which may take special actions
 871  * @mode: the task state to sleep in
 872  *
 873  * There is a standard hashed waitqueue table for generic use. This
 874  * is the part of the hashtable's accessor API that waits on a bit.
 875  * For instance, if one were to have waiters on a bitflag, one would
 876  * call wait_on_bit() in threads waiting for the bit to clear.
 877  * One uses wait_on_bit() where one is waiting for the bit to clear,
 878  * but has no intention of setting it.
 879  */
 880 static inline int wait_on_bit(void *word, int bit,
 881                                 int (*action)(void *), unsigned mode)
 882 {
 883         if (!test_bit(bit, word))
 884                 return 0;
 885         return out_of_line_wait_on_bit(word, bit, action, mode);
 886 }
 887
 888 /**
 889  * wait_on_bit_lock - wait for a bit to be cleared, when wanting to set it
 890  * @word: the word being waited on, a kernel virtual address
 891  * @bit: the bit of the word being waited on
 892  * @action: the function used to sleep, which may take special actions
 893  * @mode: the task state to sleep in
 894  *
 895  * There is a standard hashed waitqueue table for generic use. This
 896  * is the part of the hashtable's accessor API that waits on a bit
 897  * when one intends to set it, for instance, trying to lock bitflags.
 898  * For instance, if one were to have waiters trying to set bitflag
 899  * and waiting for it to clear before setting it, one would call
 900  * wait_on_bit() in threads waiting to be able to set the bit.
 901  * One uses wait_on_bit_lock() where one is waiting for the bit to
 902  * clear with the intention of setting it, and when done, clearing it.
 903  */
 904 static inline int wait_on_bit_lock(void *word, int bit,
 905                                 int (*action)(void *), unsigned mode)
 906 {
 907         if (!test_and_set_bit(bit, word))
 908                 return 0;
 909         return out_of_line_wait_on_bit_lock(word, bit, action, mode);
 910 }
 911
 912 /**
 913  * wait_on_atomic_t - Wait for an atomic_t to become 0
 914  * @val: The atomic value being waited on, a kernel virtual address
 915  * @action: the function used to sleep, which may take special actions
 916  * @mode: the task state to sleep in
 917  *
 918  * Wait for an atomic_t to become 0.  We abuse the bit-wait waitqueue table for
 919  * the purpose of getting a waitqueue, but we set the key to a bit number
 920  * outside of the target 'word'.
 921  */
 922 static inline
 923 int wait_on_atomic_t(atomic_t *val, int (*action)(atomic_t *), unsigned mode)
 924 {
 925         if (atomic_read(val) == 0)
 926                 return 0;
 927         return out_of_line_wait_on_atomic_t(val, action, mode);
 928 }
 929
 930 #endif