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