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_cond_timeout(condition, ret)                            \
 183 ({                                                                      \
 184         bool __cond = (condition);                                      \
 185         if (__cond && !ret)                                             \
 186                 ret = 1;                                                \
 187         __cond || !ret;                                                 \
 188 })
 189
 190 #define __wait_event(wq, condition)                                     \
 191 do {                                                                    \
 192         DEFINE_WAIT(__wait);                                            \
 193                                                                         \
 194         for (;;) {                                                      \
 195                 prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE);    \
 196                 if (condition)                                          \
 197                         break;                                          \
 198                 schedule();                                             \
 199         }                                                               \
 200         finish_wait(&wq, &__wait);                                      \
 201 } while (0)
 202
 203 /**
 204  * wait_event - sleep until a condition gets true
 205  * @wq: the waitqueue to wait on
 206  * @condition: a C expression for the event to wait for
 207  *
 208  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 209  * @condition evaluates to true. The @condition is checked each time
 210  * the waitqueue @wq is woken up.
 211  *
 212  * wake_up() has to be called after changing any variable that could
 213  * change the result of the wait condition.
 214  */
 215 #define wait_event(wq, condition)                                       \
 216 do {                                                                    \
 217         if (condition)                                                  \
 218                 break;                                                  \
 219         __wait_event(wq, condition);                                    \
 220 } while (0)
 221
 222 #define __wait_event_timeout(wq, condition, ret)                        \
 223 do {                                                                    \
 224         DEFINE_WAIT(__wait);                                            \
 225                                                                         \
 226         for (;;) {                                                      \
 227                 prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE);    \
 228                 if (___wait_cond_timeout(condition, ret))               \
 229                         break;                                          \
 230                 ret = schedule_timeout(ret);                            \
 231         }                                                               \
 232         finish_wait(&wq, &__wait);                                      \
 233 } while (0)
 234
 235 /**
 236  * wait_event_timeout - sleep until a condition gets true or a timeout elapses
 237  * @wq: the waitqueue to wait on
 238  * @condition: a C expression for the event to wait for
 239  * @timeout: timeout, in jiffies
 240  *
 241  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 242  * @condition evaluates to true. The @condition is checked each time
 243  * the waitqueue @wq is woken up.
 244  *
 245  * wake_up() has to be called after changing any variable that could
 246  * change the result of the wait condition.
 247  *
 248  * The function returns 0 if the @timeout elapsed, or the remaining
 249  * jiffies (at least 1) if the @condition evaluated to %true before
 250  * the @timeout elapsed.
 251  */
 252 #define wait_event_timeout(wq, condition, timeout)                      \
 253 ({                                                                      \
 254         long __ret = timeout;                                           \
 255         if (!(condition))                                               \
 256                 __wait_event_timeout(wq, condition, __ret);             \
 257         __ret;                                                          \
 258 })
 259
 260 #define __wait_event_interruptible(wq, condition, ret)                  \
 261 do {                                                                    \
 262         DEFINE_WAIT(__wait);                                            \
 263                                                                         \
 264         for (;;) {                                                      \
 265                 prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE);      \
 266                 if (condition)                                          \
 267                         break;                                          \
 268                 if (signal_pending(current)) {                          \
 269                         ret = -ERESTARTSYS;                             \
 270                         break;                                          \
 271                 }                                                       \
 272                 schedule();                                             \
 273         }                                                               \
 274         finish_wait(&wq, &__wait);                                      \
 275 } while (0)
 276
 277 /**
 278  * wait_event_interruptible - sleep until a condition gets true
 279  * @wq: the waitqueue to wait on
 280  * @condition: a C expression for the event to wait for
 281  *
 282  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 283  * @condition evaluates to true or a signal is received.
 284  * The @condition is checked each time the waitqueue @wq is woken up.
 285  *
 286  * wake_up() has to be called after changing any variable that could
 287  * change the result of the wait condition.
 288  *
 289  * The function will return -ERESTARTSYS if it was interrupted by a
 290  * signal and 0 if @condition evaluated to true.
 291  */
 292 #define wait_event_interruptible(wq, condition)                         \
 293 ({                                                                      \
 294         int __ret = 0;                                                  \
 295         if (!(condition))                                               \
 296                 __wait_event_interruptible(wq, condition, __ret);       \
 297         __ret;                                                          \
 298 })
 299
 300 #define __wait_event_interruptible_timeout(wq, condition, ret)          \
 301 do {                                                                    \
 302         DEFINE_WAIT(__wait);                                            \
 303                                                                         \
 304         for (;;) {                                                      \
 305                 prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE);      \
 306                 if (___wait_cond_timeout(condition, ret))               \
 307                         break;                                          \
 308                 if (signal_pending(current)) {                          \
 309                         ret = -ERESTARTSYS;                             \
 310                         break;                                          \
 311                 }                                                       \
 312                 ret = schedule_timeout(ret);                            \
 313         }                                                               \
 314         finish_wait(&wq, &__wait);                                      \
 315 } while (0)
 316
 317 /**
 318  * wait_event_interruptible_timeout - sleep until a condition gets true or a timeout elapses
 319  * @wq: the waitqueue to wait on
 320  * @condition: a C expression for the event to wait for
 321  * @timeout: timeout, in jiffies
 322  *
 323  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 324  * @condition evaluates to true or a signal is received.
 325  * The @condition is checked each time the waitqueue @wq is woken up.
 326  *
 327  * wake_up() has to be called after changing any variable that could
 328  * change the result of the wait condition.
 329  *
 330  * Returns:
 331  * 0 if the @timeout elapsed, -%ERESTARTSYS if it was interrupted by
 332  * a signal, or the remaining jiffies (at least 1) if the @condition
 333  * evaluated to %true before the @timeout elapsed.
 334  */
 335 #define wait_event_interruptible_timeout(wq, condition, timeout)        \
 336 ({                                                                      \
 337         long __ret = timeout;                                           \
 338         if (!(condition))                                               \
 339                 __wait_event_interruptible_timeout(wq, condition, __ret); \
 340         __ret;                                                          \
 341 })
 342
 343 #define __wait_event_hrtimeout(wq, condition, timeout, state)           \
 344 ({                                                                      \
 345         int __ret = 0;                                                  \
 346         DEFINE_WAIT(__wait);                                            \
 347         struct hrtimer_sleeper __t;                                     \
 348                                                                         \
 349         hrtimer_init_on_stack(&__t.timer, CLOCK_MONOTONIC,              \
 350                               HRTIMER_MODE_REL);                        \
 351         hrtimer_init_sleeper(&__t, current);                            \
 352         if ((timeout).tv64 != KTIME_MAX)                                \
 353                 hrtimer_start_range_ns(&__t.timer, timeout,             \
 354                                        current->timer_slack_ns,         \
 355                                        HRTIMER_MODE_REL);               \
 356                                                                         \
 357         for (;;) {                                                      \
 358                 prepare_to_wait(&wq, &__wait, state);                   \
 359                 if (condition)                                          \
 360                         break;                                          \
 361                 if (state == TASK_INTERRUPTIBLE &&                      \
 362                     signal_pending(current)) {                          \
 363                         __ret = -ERESTARTSYS;                           \
 364                         break;                                          \
 365                 }                                                       \
 366                 if (!__t.task) {                                        \
 367                         __ret = -ETIME;                                 \
 368                         break;                                          \
 369                 }                                                       \
 370                 schedule();                                             \
 371         }                                                               \
 372                                                                         \
 373         hrtimer_cancel(&__t.timer);                                     \
 374         destroy_hrtimer_on_stack(&__t.timer);                           \
 375         finish_wait(&wq, &__wait);                                      \
 376         __ret;                                                          \
 377 })
 378
 379 /**
 380  * wait_event_hrtimeout - sleep until a condition gets true or a timeout elapses
 381  * @wq: the waitqueue to wait on
 382  * @condition: a C expression for the event to wait for
 383  * @timeout: timeout, as a ktime_t
 384  *
 385  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 386  * @condition evaluates to true or a signal is received.
 387  * The @condition is checked each time the waitqueue @wq is woken up.
 388  *
 389  * wake_up() has to be called after changing any variable that could
 390  * change the result of the wait condition.
 391  *
 392  * The function returns 0 if @condition became true, or -ETIME if the timeout
 393  * elapsed.
 394  */
 395 #define wait_event_hrtimeout(wq, condition, timeout)                    \
 396 ({                                                                      \
 397         int __ret = 0;                                                  \
 398         if (!(condition))                                               \
 399                 __ret = __wait_event_hrtimeout(wq, condition, timeout,  \
 400                                                TASK_UNINTERRUPTIBLE);   \
 401         __ret;                                                          \
 402 })
 403
 404 /**
 405  * wait_event_interruptible_hrtimeout - sleep until a condition gets true or a timeout elapses
 406  * @wq: the waitqueue to wait on
 407  * @condition: a C expression for the event to wait for
 408  * @timeout: timeout, as a ktime_t
 409  *
 410  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 411  * @condition evaluates to true or a signal is received.
 412  * The @condition is checked each time the waitqueue @wq is woken up.
 413  *
 414  * wake_up() has to be called after changing any variable that could
 415  * change the result of the wait condition.
 416  *
 417  * The function returns 0 if @condition became true, -ERESTARTSYS if it was
 418  * interrupted by a signal, or -ETIME if the timeout elapsed.
 419  */
 420 #define wait_event_interruptible_hrtimeout(wq, condition, timeout)      \
 421 ({                                                                      \
 422         long __ret = 0;                                                 \
 423         if (!(condition))                                               \
 424                 __ret = __wait_event_hrtimeout(wq, condition, timeout,  \
 425                                                TASK_INTERRUPTIBLE);     \
 426         __ret;                                                          \
 427 })
 428
 429 #define __wait_event_interruptible_exclusive(wq, condition, ret)        \
 430 do {                                                                    \
 431         __label__ __out;                                                \
 432         DEFINE_WAIT(__wait);                                            \
 433                                                                         \
 434         for (;;) {                                                      \
 435                 prepare_to_wait_exclusive(&wq, &__wait,                 \
 436                                         TASK_INTERRUPTIBLE);            \
 437                 if (condition)                                          \
 438                         break;                                          \
 439                 if (signal_pending(current)) {                          \
 440                         ret = -ERESTARTSYS;                             \
 441                         abort_exclusive_wait(&wq, &__wait,              \
 442                                 TASK_INTERRUPTIBLE, NULL);              \
 443                         goto __out;                                     \
 444                 }                                                       \
 445                 schedule();                                             \
 446         }                                                               \
 447         finish_wait(&wq, &__wait);                                      \
 448 __out:  ;                                                               \
 449 } while (0)
 450
 451 #define wait_event_interruptible_exclusive(wq, condition)               \
 452 ({                                                                      \
 453         int __ret = 0;                                                  \
 454         if (!(condition))                                               \
 455                 __wait_event_interruptible_exclusive(wq, condition, __ret);\
 456         __ret;                                                          \
 457 })
 458
 459
 460 #define __wait_event_interruptible_locked(wq, condition, exclusive, irq) \
 461 ({                                                                      \
 462         int __ret = 0;                                                  \
 463         DEFINE_WAIT(__wait);                                            \
 464         if (exclusive)                                                  \
 465                 __wait.flags |= WQ_FLAG_EXCLUSIVE;                      \
 466         do {                                                            \
 467                 if (likely(list_empty(&__wait.task_list)))              \
 468                         __add_wait_queue_tail(&(wq), &__wait);          \
 469                 set_current_state(TASK_INTERRUPTIBLE);                  \
 470                 if (signal_pending(current)) {                          \
 471                         __ret = -ERESTARTSYS;                           \
 472                         break;                                          \
 473                 }                                                       \
 474                 if (irq)                                                \
 475                         spin_unlock_irq(&(wq).lock);                    \
 476                 else                                                    \
 477                         spin_unlock(&(wq).lock);                        \
 478                 schedule();                                             \
 479                 if (irq)                                                \
 480                         spin_lock_irq(&(wq).lock);                      \
 481                 else                                                    \
 482                         spin_lock(&(wq).lock);                          \
 483         } while (!(condition));                                         \
 484         __remove_wait_queue(&(wq), &__wait);                            \
 485         __set_current_state(TASK_RUNNING);                              \
 486         __ret;                                                          \
 487 })
 488
 489
 490 /**
 491  * wait_event_interruptible_locked - sleep until a condition gets true
 492  * @wq: the waitqueue to wait on
 493  * @condition: a C expression for the event to wait for
 494  *
 495  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 496  * @condition evaluates to true or a signal is received.
 497  * The @condition is checked each time the waitqueue @wq is woken up.
 498  *
 499  * It must be called with wq.lock being held.  This spinlock is
 500  * unlocked while sleeping but @condition testing is done while lock
 501  * is held and when this macro exits the lock is held.
 502  *
 503  * The lock is locked/unlocked using spin_lock()/spin_unlock()
 504  * functions which must match the way they are locked/unlocked outside
 505  * of this macro.
 506  *
 507  * wake_up_locked() has to be called after changing any variable that could
 508  * change the result of the wait condition.
 509  *
 510  * The function will return -ERESTARTSYS if it was interrupted by a
 511  * signal and 0 if @condition evaluated to true.
 512  */
 513 #define wait_event_interruptible_locked(wq, condition)                  \
 514         ((condition)                                                    \
 515          ? 0 : __wait_event_interruptible_locked(wq, condition, 0, 0))
 516
 517 /**
 518  * wait_event_interruptible_locked_irq - sleep until a condition gets true
 519  * @wq: the waitqueue to wait on
 520  * @condition: a C expression for the event to wait for
 521  *
 522  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 523  * @condition evaluates to true or a signal is received.
 524  * The @condition is checked each time the waitqueue @wq is woken up.
 525  *
 526  * It must be called with wq.lock being held.  This spinlock is
 527  * unlocked while sleeping but @condition testing is done while lock
 528  * is held and when this macro exits the lock is held.
 529  *
 530  * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq()
 531  * functions which must match the way they are locked/unlocked outside
 532  * of this macro.
 533  *
 534  * wake_up_locked() has to be called after changing any variable that could
 535  * change the result of the wait condition.
 536  *
 537  * The function will return -ERESTARTSYS if it was interrupted by a
 538  * signal and 0 if @condition evaluated to true.
 539  */
 540 #define wait_event_interruptible_locked_irq(wq, condition)              \
 541         ((condition)                                                    \
 542          ? 0 : __wait_event_interruptible_locked(wq, condition, 0, 1))
 543
 544 /**
 545  * wait_event_interruptible_exclusive_locked - sleep exclusively until a condition gets true
 546  * @wq: the waitqueue to wait on
 547  * @condition: a C expression for the event to wait for
 548  *
 549  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 550  * @condition evaluates to true or a signal is received.
 551  * The @condition is checked each time the waitqueue @wq is woken up.
 552  *
 553  * It must be called with wq.lock being held.  This spinlock is
 554  * unlocked while sleeping but @condition testing is done while lock
 555  * is held and when this macro exits the lock is held.
 556  *
 557  * The lock is locked/unlocked using spin_lock()/spin_unlock()
 558  * functions which must match the way they are locked/unlocked outside
 559  * of this macro.
 560  *
 561  * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
 562  * set thus when other process waits process on the list if this
 563  * process is awaken further processes are not considered.
 564  *
 565  * wake_up_locked() has to be called after changing any variable that could
 566  * change the result of the wait condition.
 567  *
 568  * The function will return -ERESTARTSYS if it was interrupted by a
 569  * signal and 0 if @condition evaluated to true.
 570  */
 571 #define wait_event_interruptible_exclusive_locked(wq, condition)        \
 572         ((condition)                                                    \
 573          ? 0 : __wait_event_interruptible_locked(wq, condition, 1, 0))
 574
 575 /**
 576  * wait_event_interruptible_exclusive_locked_irq - sleep until a condition gets true
 577  * @wq: the waitqueue to wait on
 578  * @condition: a C expression for the event to wait for
 579  *
 580  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 581  * @condition evaluates to true or a signal is received.
 582  * The @condition is checked each time the waitqueue @wq is woken up.
 583  *
 584  * It must be called with wq.lock being held.  This spinlock is
 585  * unlocked while sleeping but @condition testing is done while lock
 586  * is held and when this macro exits the lock is held.
 587  *
 588  * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq()
 589  * functions which must match the way they are locked/unlocked outside
 590  * of this macro.
 591  *
 592  * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
 593  * set thus when other process waits process on the list if this
 594  * process is awaken further processes are not considered.
 595  *
 596  * wake_up_locked() has to be called after changing any variable that could
 597  * change the result of the wait condition.
 598  *
 599  * The function will return -ERESTARTSYS if it was interrupted by a
 600  * signal and 0 if @condition evaluated to true.
 601  */
 602 #define wait_event_interruptible_exclusive_locked_irq(wq, condition)    \
 603         ((condition)                                                    \
 604          ? 0 : __wait_event_interruptible_locked(wq, condition, 1, 1))
 605
 606
 607
 608 #define __wait_event_killable(wq, condition, ret)                       \
 609 do {                                                                    \
 610         DEFINE_WAIT(__wait);                                            \
 611                                                                         \
 612         for (;;) {                                                      \
 613                 prepare_to_wait(&wq, &__wait, TASK_KILLABLE);           \
 614                 if (condition)                                          \
 615                         break;                                          \
 616                 if (!fatal_signal_pending(current)) {                   \
 617                         schedule();                                     \
 618                         continue;                                       \
 619                 }                                                       \
 620                 ret = -ERESTARTSYS;                                     \
 621                 break;                                                  \
 622         }                                                               \
 623         finish_wait(&wq, &__wait);                                      \
 624 } while (0)
 625
 626 /**
 627  * wait_event_killable - sleep until a condition gets true
 628  * @wq: the waitqueue to wait on
 629  * @condition: a C expression for the event to wait for
 630  *
 631  * The process is put to sleep (TASK_KILLABLE) until the
 632  * @condition evaluates to true or a signal is received.
 633  * The @condition is checked each time the waitqueue @wq is woken up.
 634  *
 635  * wake_up() has to be called after changing any variable that could
 636  * change the result of the wait condition.
 637  *
 638  * The function will return -ERESTARTSYS if it was interrupted by a
 639  * signal and 0 if @condition evaluated to true.
 640  */
 641 #define wait_event_killable(wq, condition)                              \
 642 ({                                                                      \
 643         int __ret = 0;                                                  \
 644         if (!(condition))                                               \
 645                 __wait_event_killable(wq, condition, __ret);            \
 646         __ret;                                                          \
 647 })
 648
 649
 650 #define __wait_event_lock_irq(wq, condition, lock, cmd)                 \
 651 do {                                                                    \
 652         DEFINE_WAIT(__wait);                                            \
 653                                                                         \
 654         for (;;) {                                                      \
 655                 prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE);    \
 656                 if (condition)                                          \
 657                         break;                                          \
 658                 spin_unlock_irq(&lock);                                 \
 659                 cmd;                                                    \
 660                 schedule();                                             \
 661                 spin_lock_irq(&lock);                                   \
 662         }                                                               \
 663         finish_wait(&wq, &__wait);                                      \
 664 } while (0)
 665
 666 /**
 667  * wait_event_lock_irq_cmd - sleep until a condition gets true. The
 668  *                           condition is checked under the lock. This
 669  *                           is expected to be called with the lock
 670  *                           taken.
 671  * @wq: the waitqueue to wait on
 672  * @condition: a C expression for the event to wait for
 673  * @lock: a locked spinlock_t, which will be released before cmd
 674  *        and schedule() and reacquired afterwards.
 675  * @cmd: a command which is invoked outside the critical section before
 676  *       sleep
 677  *
 678  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 679  * @condition evaluates to true. The @condition is checked each time
 680  * the waitqueue @wq is woken up.
 681  *
 682  * wake_up() has to be called after changing any variable that could
 683  * change the result of the wait condition.
 684  *
 685  * This is supposed to be called while holding the lock. The lock is
 686  * dropped before invoking the cmd and going to sleep and is reacquired
 687  * afterwards.
 688  */
 689 #define wait_event_lock_irq_cmd(wq, condition, lock, cmd)               \
 690 do {                                                                    \
 691         if (condition)                                                  \
 692                 break;                                                  \
 693         __wait_event_lock_irq(wq, condition, lock, cmd);                \
 694 } while (0)
 695
 696 /**
 697  * wait_event_lock_irq - sleep until a condition gets true. The
 698  *                       condition is checked under the lock. This
 699  *                       is expected to be called with the lock
 700  *                       taken.
 701  * @wq: the waitqueue to wait on
 702  * @condition: a C expression for the event to wait for
 703  * @lock: a locked spinlock_t, which will be released before schedule()
 704  *        and reacquired afterwards.
 705  *
 706  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 707  * @condition evaluates to true. The @condition is checked each time
 708  * the waitqueue @wq is woken up.
 709  *
 710  * wake_up() has to be called after changing any variable that could
 711  * change the result of the wait condition.
 712  *
 713  * This is supposed to be called while holding the lock. The lock is
 714  * dropped before going to sleep and is reacquired afterwards.
 715  */
 716 #define wait_event_lock_irq(wq, condition, lock)                        \
 717 do {                                                                    \
 718         if (condition)                                                  \
 719                 break;                                                  \
 720         __wait_event_lock_irq(wq, condition, lock, );                   \
 721 } while (0)
 722
 723
 724 #define __wait_event_interruptible_lock_irq(wq, condition,              \
 725                                             lock, ret, cmd)             \
 726 do {                                                                    \
 727         DEFINE_WAIT(__wait);                                            \
 728                                                                         \
 729         for (;;) {                                                      \
 730                 prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE);      \
 731                 if (condition)                                          \
 732                         break;                                          \
 733                 if (signal_pending(current)) {                          \
 734                         ret = -ERESTARTSYS;                             \
 735                         break;                                          \
 736                 }                                                       \
 737                 spin_unlock_irq(&lock);                                 \
 738                 cmd;                                                    \
 739                 schedule();                                             \
 740                 spin_lock_irq(&lock);                                   \
 741         }                                                               \
 742         finish_wait(&wq, &__wait);                                      \
 743 } while (0)
 744
 745 /**
 746  * wait_event_interruptible_lock_irq_cmd - sleep until a condition gets true.
 747  *              The condition is checked under the lock. This is expected to
 748  *              be called with the lock taken.
 749  * @wq: the waitqueue to wait on
 750  * @condition: a C expression for the event to wait for
 751  * @lock: a locked spinlock_t, which will be released before cmd and
 752  *        schedule() and reacquired afterwards.
 753  * @cmd: a command which is invoked outside the critical section before
 754  *       sleep
 755  *
 756  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 757  * @condition evaluates to true or a signal is received. The @condition is
 758  * checked each time the waitqueue @wq is woken up.
 759  *
 760  * wake_up() has to be called after changing any variable that could
 761  * change the result of the wait condition.
 762  *
 763  * This is supposed to be called while holding the lock. The lock is
 764  * dropped before invoking the cmd and going to sleep and is reacquired
 765  * afterwards.
 766  *
 767  * The macro will return -ERESTARTSYS if it was interrupted by a signal
 768  * and 0 if @condition evaluated to true.
 769  */
 770 #define wait_event_interruptible_lock_irq_cmd(wq, condition, lock, cmd) \
 771 ({                                                                      \
 772         int __ret = 0;                                                  \
 773                                                                         \
 774         if (!(condition))                                               \
 775                 __wait_event_interruptible_lock_irq(wq, condition,      \
 776                                                     lock, __ret, cmd);  \
 777         __ret;                                                          \
 778 })
 779
 780 /**
 781  * wait_event_interruptible_lock_irq - sleep until a condition gets true.
 782  *              The condition is checked under the lock. This is expected
 783  *              to be called with the lock taken.
 784  * @wq: the waitqueue to wait on
 785  * @condition: a C expression for the event to wait for
 786  * @lock: a locked spinlock_t, which will be released before schedule()
 787  *        and reacquired afterwards.
 788  *
 789  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 790  * @condition evaluates to true or signal is received. The @condition is
 791  * checked each time the waitqueue @wq is woken up.
 792  *
 793  * wake_up() has to be called after changing any variable that could
 794  * change the result of the wait condition.
 795  *
 796  * This is supposed to be called while holding the lock. The lock is
 797  * dropped before going to sleep and is reacquired afterwards.
 798  *
 799  * The macro will return -ERESTARTSYS if it was interrupted by a signal
 800  * and 0 if @condition evaluated to true.
 801  */
 802 #define wait_event_interruptible_lock_irq(wq, condition, lock)          \
 803 ({                                                                      \
 804         int __ret = 0;                                                  \
 805                                                                         \
 806         if (!(condition))                                               \
 807                 __wait_event_interruptible_lock_irq(wq, condition,      \
 808                                                     lock, __ret, );     \
 809         __ret;                                                          \
 810 })
 811
 812 #define __wait_event_interruptible_lock_irq_timeout(wq, condition,      \
 813                                                     lock, ret)          \
 814 do {                                                                    \
 815         DEFINE_WAIT(__wait);                                            \
 816                                                                         \
 817         for (;;) {                                                      \
 818                 prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE);      \
 819                 if (___wait_cond_timeout(condition, ret))               \
 820                         break;                                          \
 821                 if (signal_pending(current)) {                          \
 822                         ret = -ERESTARTSYS;                             \
 823                         break;                                          \
 824                 }                                                       \
 825                 spin_unlock_irq(&lock);                                 \
 826                 ret = schedule_timeout(ret);                            \
 827                 spin_lock_irq(&lock);                                   \
 828         }                                                               \
 829         finish_wait(&wq, &__wait);                                      \
 830 } while (0)
 831
 832 /**
 833  * wait_event_interruptible_lock_irq_timeout - sleep until a condition gets true or a timeout elapses.
 834  *              The condition is checked under the lock. This is expected
 835  *              to be called with the lock taken.
 836  * @wq: the waitqueue to wait on
 837  * @condition: a C expression for the event to wait for
 838  * @lock: a locked spinlock_t, which will be released before schedule()
 839  *        and reacquired afterwards.
 840  * @timeout: timeout, in jiffies
 841  *
 842  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 843  * @condition evaluates to true or signal is received. The @condition is
 844  * checked each time the waitqueue @wq is woken up.
 845  *
 846  * wake_up() has to be called after changing any variable that could
 847  * change the result of the wait condition.
 848  *
 849  * This is supposed to be called while holding the lock. The lock is
 850  * dropped before going to sleep and is reacquired afterwards.
 851  *
 852  * The function returns 0 if the @timeout elapsed, -ERESTARTSYS if it
 853  * was interrupted by a signal, and the remaining jiffies otherwise
 854  * if the condition evaluated to true before the timeout elapsed.
 855  */
 856 #define wait_event_interruptible_lock_irq_timeout(wq, condition, lock,  \
 857                                                   timeout)              \
 858 ({                                                                      \
 859         int __ret = timeout;                                            \
 860                                                                         \
 861         if (!(condition))                                               \
 862                 __wait_event_interruptible_lock_irq_timeout(            \
 863                                         wq, condition, lock, __ret);    \
 864         __ret;                                                          \
 865 })
 866
 867
 868 /*
 869  * These are the old interfaces to sleep waiting for an event.
 870  * They are racy.  DO NOT use them, use the wait_event* interfaces above.
 871  * We plan to remove these interfaces.
 872  */
 873 extern void sleep_on(wait_queue_head_t *q);
 874 extern long sleep_on_timeout(wait_queue_head_t *q,
 875                                       signed long timeout);
 876 extern void interruptible_sleep_on(wait_queue_head_t *q);
 877 extern long interruptible_sleep_on_timeout(wait_queue_head_t *q,
 878                                            signed long timeout);
 879
 880 /*
 881  * Waitqueues which are removed from the waitqueue_head at wakeup time
 882  */
 883 void prepare_to_wait(wait_queue_head_t *q, wait_queue_t *wait, int state);
 884 void prepare_to_wait_exclusive(wait_queue_head_t *q, wait_queue_t *wait, int state);
 885 void finish_wait(wait_queue_head_t *q, wait_queue_t *wait);
 886 void abort_exclusive_wait(wait_queue_head_t *q, wait_queue_t *wait,
 887                         unsigned int mode, void *key);
 888 int autoremove_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 889 int wake_bit_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 890
 891 #define DEFINE_WAIT_FUNC(name, function)                                \
 892         wait_queue_t name = {                                           \
 893                 .private        = current,                              \
 894                 .func           = function,                             \
 895                 .task_list      = LIST_HEAD_INIT((name).task_list),     \
 896         }
 897
 898 #define DEFINE_WAIT(name) DEFINE_WAIT_FUNC(name, autoremove_wake_function)
 899
 900 #define DEFINE_WAIT_BIT(name, word, bit)                                \
 901         struct wait_bit_queue name = {                                  \
 902                 .key = __WAIT_BIT_KEY_INITIALIZER(word, bit),           \
 903                 .wait   = {                                             \
 904                         .private        = current,                      \
 905                         .func           = wake_bit_function,            \
 906                         .task_list      =                               \
 907                                 LIST_HEAD_INIT((name).wait.task_list),  \
 908                 },                                                      \
 909         }
 910
 911 #define init_wait(wait)                                                 \
 912         do {                                                            \
 913                 (wait)->private = current;                              \
 914                 (wait)->func = autoremove_wake_function;                \
 915                 INIT_LIST_HEAD(&(wait)->task_list);                     \
 916                 (wait)->flags = 0;                                      \
 917         } while (0)
 918
 919 /**
 920  * wait_on_bit - wait for a bit to be cleared
 921  * @word: the word being waited on, a kernel virtual address
 922  * @bit: the bit of the word being waited on
 923  * @action: the function used to sleep, which may take special actions
 924  * @mode: the task state to sleep in
 925  *
 926  * There is a standard hashed waitqueue table for generic use. This
 927  * is the part of the hashtable's accessor API that waits on a bit.
 928  * For instance, if one were to have waiters on a bitflag, one would
 929  * call wait_on_bit() in threads waiting for the bit to clear.
 930  * One uses wait_on_bit() where one is waiting for the bit to clear,
 931  * but has no intention of setting it.
 932  */
 933 static inline int wait_on_bit(void *word, int bit,
 934                                 int (*action)(void *), unsigned mode)
 935 {
 936         if (!test_bit(bit, word))
 937                 return 0;
 938         return out_of_line_wait_on_bit(word, bit, action, mode);
 939 }
 940
 941 /**
 942  * wait_on_bit_lock - wait for a bit to be cleared, when wanting to set it
 943  * @word: the word being waited on, a kernel virtual address
 944  * @bit: the bit of the word being waited on
 945  * @action: the function used to sleep, which may take special actions
 946  * @mode: the task state to sleep in
 947  *
 948  * There is a standard hashed waitqueue table for generic use. This
 949  * is the part of the hashtable's accessor API that waits on a bit
 950  * when one intends to set it, for instance, trying to lock bitflags.
 951  * For instance, if one were to have waiters trying to set bitflag
 952  * and waiting for it to clear before setting it, one would call
 953  * wait_on_bit() in threads waiting to be able to set the bit.
 954  * One uses wait_on_bit_lock() where one is waiting for the bit to
 955  * clear with the intention of setting it, and when done, clearing it.
 956  */
 957 static inline int wait_on_bit_lock(void *word, int bit,
 958                                 int (*action)(void *), unsigned mode)
 959 {
 960         if (!test_and_set_bit(bit, word))
 961                 return 0;
 962         return out_of_line_wait_on_bit_lock(word, bit, action, mode);
 963 }
 964
 965 /**
 966  * wait_on_atomic_t - Wait for an atomic_t to become 0
 967  * @val: The atomic value being waited on, a kernel virtual address
 968  * @action: the function used to sleep, which may take special actions
 969  * @mode: the task state to sleep in
 970  *
 971  * Wait for an atomic_t to become 0.  We abuse the bit-wait waitqueue table for
 972  * the purpose of getting a waitqueue, but we set the key to a bit number
 973  * outside of the target 'word'.
 974  */
 975 static inline
 976 int wait_on_atomic_t(atomic_t *val, int (*action)(atomic_t *), unsigned mode)
 977 {
 978         if (atomic_read(val) == 0)
 979                 return 0;
 980         return out_of_line_wait_on_atomic_t(val, action, mode);
 981 }
 982
 983 #endif