include/linux/wait.h

   1 #ifndef _LINUX_WAIT_H
   2 #define _LINUX_WAIT_H
   3 /*
   4  * Linux wait queue related types and methods
   5  */
   6 #include <linux/list.h>
   7 #include <linux/stddef.h>
   8 #include <linux/spinlock.h>
   9 #include <asm/current.h>
  10 #include <uapi/linux/wait.h>
  11
  12 typedef struct __wait_queue wait_queue_t;
  13 typedef int (*wait_queue_func_t)(wait_queue_t *wait, unsigned mode, int flags, void *key);
  14 int default_wake_function(wait_queue_t *wait, unsigned mode, int flags, void *key);
  15
  16 struct __wait_queue {
  17         unsigned int            flags;
  18 #define WQ_FLAG_EXCLUSIVE       0x01
  19         void                    *private;
  20         wait_queue_func_t       func;
  21         struct list_head        task_list;
  22 };
  23
  24 struct wait_bit_key {
  25         void                    *flags;
  26         int                     bit_nr;
  27 #define WAIT_ATOMIC_T_BIT_NR    -1
  28         unsigned long           private;
  29 };
  30
  31 struct wait_bit_queue {
  32         struct wait_bit_key     key;
  33         wait_queue_t            wait;
  34 };
  35
  36 struct __wait_queue_head {
  37         spinlock_t              lock;
  38         struct list_head        task_list;
  39 };
  40 typedef struct __wait_queue_head wait_queue_head_t;
  41
  42 struct task_struct;
  43
  44 /*
  45  * Macros for declaration and initialisaton of the datatypes
  46  */
  47
  48 #define __WAITQUEUE_INITIALIZER(name, tsk) {                            \
  49         .private        = tsk,                                          \
  50         .func           = default_wake_function,                        \
  51         .task_list      = { NULL, NULL } }
  52
  53 #define DECLARE_WAITQUEUE(name, tsk)                                    \
  54         wait_queue_t name = __WAITQUEUE_INITIALIZER(name, tsk)
  55
  56 #define __WAIT_QUEUE_HEAD_INITIALIZER(name) {                           \
  57         .lock           = __SPIN_LOCK_UNLOCKED(name.lock),              \
  58         .task_list      = { &(name).task_list, &(name).task_list } }
  59
  60 #define DECLARE_WAIT_QUEUE_HEAD(name) \
  61         wait_queue_head_t name = __WAIT_QUEUE_HEAD_INITIALIZER(name)
  62
  63 #define __WAIT_BIT_KEY_INITIALIZER(word, bit)                           \
  64         { .flags = word, .bit_nr = bit, }
  65
  66 #define __WAIT_ATOMIC_T_KEY_INITIALIZER(p)                              \
  67         { .flags = p, .bit_nr = WAIT_ATOMIC_T_BIT_NR, }
  68
  69 extern void __init_waitqueue_head(wait_queue_head_t *q, const char *name, struct lock_class_key *);
  70
  71 #define init_waitqueue_head(q)                          \
  72         do {                                            \
  73                 static struct lock_class_key __key;     \
  74                                                         \
  75                 __init_waitqueue_head((q), #q, &__key); \
  76         } while (0)
  77
  78 #ifdef CONFIG_LOCKDEP
  79 # define __WAIT_QUEUE_HEAD_INIT_ONSTACK(name) \
  80         ({ init_waitqueue_head(&name); name; })
  81 # define DECLARE_WAIT_QUEUE_HEAD_ONSTACK(name) \
  82         wait_queue_head_t name = __WAIT_QUEUE_HEAD_INIT_ONSTACK(name)
  83 #else
  84 # define DECLARE_WAIT_QUEUE_HEAD_ONSTACK(name) DECLARE_WAIT_QUEUE_HEAD(name)
  85 #endif
  86
  87 static inline void init_waitqueue_entry(wait_queue_t *q, struct task_struct *p)
  88 {
  89         q->flags        = 0;
  90         q->private      = p;
  91         q->func         = default_wake_function;
  92 }
  93
  94 static inline void
  95 init_waitqueue_func_entry(wait_queue_t *q, wait_queue_func_t func)
  96 {
  97         q->flags        = 0;
  98         q->private      = NULL;
  99         q->func         = func;
 100 }
 101
 102 static inline int waitqueue_active(wait_queue_head_t *q)
 103 {
 104         return !list_empty(&q->task_list);
 105 }
 106
 107 extern void add_wait_queue(wait_queue_head_t *q, wait_queue_t *wait);
 108 extern void add_wait_queue_exclusive(wait_queue_head_t *q, wait_queue_t *wait);
 109 extern void remove_wait_queue(wait_queue_head_t *q, wait_queue_t *wait);
 110
 111 static inline void __add_wait_queue(wait_queue_head_t *head, wait_queue_t *new)
 112 {
 113         list_add(&new->task_list, &head->task_list);
 114 }
 115
 116 /*
 117  * Used for wake-one threads:
 118  */
 119 static inline void
 120 __add_wait_queue_exclusive(wait_queue_head_t *q, wait_queue_t *wait)
 121 {
 122         wait->flags |= WQ_FLAG_EXCLUSIVE;
 123         __add_wait_queue(q, wait);
 124 }
 125
 126 static inline void __add_wait_queue_tail(wait_queue_head_t *head,
 127                                          wait_queue_t *new)
 128 {
 129         list_add_tail(&new->task_list, &head->task_list);
 130 }
 131
 132 static inline void
 133 __add_wait_queue_tail_exclusive(wait_queue_head_t *q, wait_queue_t *wait)
 134 {
 135         wait->flags |= WQ_FLAG_EXCLUSIVE;
 136         __add_wait_queue_tail(q, wait);
 137 }
 138
 139 static inline void
 140 __remove_wait_queue(wait_queue_head_t *head, wait_queue_t *old)
 141 {
 142         list_del(&old->task_list);
 143 }
 144
 145 typedef int wait_bit_action_f(struct wait_bit_key *);
 146 void __wake_up(wait_queue_head_t *q, unsigned int mode, int nr, void *key);
 147 void __wake_up_locked_key(wait_queue_head_t *q, unsigned int mode, void *key);
 148 void __wake_up_sync_key(wait_queue_head_t *q, unsigned int mode, int nr, void *key);
 149 void __wake_up_locked(wait_queue_head_t *q, unsigned int mode, int nr);
 150 void __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr);
 151 void __wake_up_bit(wait_queue_head_t *, void *, int);
 152 int __wait_on_bit(wait_queue_head_t *, struct wait_bit_queue *, wait_bit_action_f *, unsigned);
 153 int __wait_on_bit_lock(wait_queue_head_t *, struct wait_bit_queue *, wait_bit_action_f *, unsigned);
 154 void wake_up_bit(void *, int);
 155 void wake_up_atomic_t(atomic_t *);
 156 int out_of_line_wait_on_bit(void *, int, wait_bit_action_f *, unsigned);
 157 int out_of_line_wait_on_bit_lock(void *, int, wait_bit_action_f *, unsigned);
 158 int out_of_line_wait_on_atomic_t(atomic_t *, int (*)(atomic_t *), unsigned);
 159 wait_queue_head_t *bit_waitqueue(void *, int);
 160
 161 #define wake_up(x)                      __wake_up(x, TASK_NORMAL, 1, NULL)
 162 #define wake_up_nr(x, nr)               __wake_up(x, TASK_NORMAL, nr, NULL)
 163 #define wake_up_all(x)                  __wake_up(x, TASK_NORMAL, 0, NULL)
 164 #define wake_up_locked(x)               __wake_up_locked((x), TASK_NORMAL, 1)
 165 #define wake_up_all_locked(x)           __wake_up_locked((x), TASK_NORMAL, 0)
 166
 167 #define wake_up_interruptible(x)        __wake_up(x, TASK_INTERRUPTIBLE, 1, NULL)
 168 #define wake_up_interruptible_nr(x, nr) __wake_up(x, TASK_INTERRUPTIBLE, nr, NULL)
 169 #define wake_up_interruptible_all(x)    __wake_up(x, TASK_INTERRUPTIBLE, 0, NULL)
 170 #define wake_up_interruptible_sync(x)   __wake_up_sync((x), TASK_INTERRUPTIBLE, 1)
 171
 172 /*
 173  * Wakeup macros to be used to report events to the targets.
 174  */
 175 #define wake_up_poll(x, m)                                              \
 176         __wake_up(x, TASK_NORMAL, 1, (void *) (m))
 177 #define wake_up_locked_poll(x, m)                                       \
 178         __wake_up_locked_key((x), TASK_NORMAL, (void *) (m))
 179 #define wake_up_interruptible_poll(x, m)                                \
 180         __wake_up(x, TASK_INTERRUPTIBLE, 1, (void *) (m))
 181 #define wake_up_interruptible_sync_poll(x, m)                           \
 182         __wake_up_sync_key((x), TASK_INTERRUPTIBLE, 1, (void *) (m))
 183
 184 #define ___wait_cond_timeout(condition)                                 \
 185 ({                                                                      \
 186         bool __cond = (condition);                                      \
 187         if (__cond && !__ret)                                           \
 188                 __ret = 1;                                              \
 189         __cond || !__ret;                                               \
 190 })
 191
 192 #define ___wait_is_interruptible(state)                                 \
 193         (!__builtin_constant_p(state) ||                                \
 194                 state == TASK_INTERRUPTIBLE || state == TASK_KILLABLE)  \
 195
 196 /*
 197  * The below macro ___wait_event() has an explicit shadow of the __ret
 198  * variable when used from the wait_event_*() macros.
 199  *
 200  * This is so that both can use the ___wait_cond_timeout() construct
 201  * to wrap the condition.
 202  *
 203  * The type inconsistency of the wait_event_*() __ret variable is also
 204  * on purpose; we use long where we can return timeout values and int
 205  * otherwise.
 206  */
 207
 208 #define ___wait_event(wq, condition, state, exclusive, ret, cmd)        \
 209 ({                                                                      \
 210         __label__ __out;                                                \
 211         wait_queue_t __wait;                                            \
 212         long __ret = ret;       /* explicit shadow */                   \
 213                                                                         \
 214         INIT_LIST_HEAD(&__wait.task_list);                              \
 215         if (exclusive)                                                  \
 216                 __wait.flags = WQ_FLAG_EXCLUSIVE;                       \
 217         else                                                            \
 218                 __wait.flags = 0;                                       \
 219                                                                         \
 220         for (;;) {                                                      \
 221                 long __int = prepare_to_wait_event(&wq, &__wait, state);\
 222                                                                         \
 223                 if (condition)                                          \
 224                         break;                                          \
 225                                                                         \
 226                 if (___wait_is_interruptible(state) && __int) {         \
 227                         __ret = __int;                                  \
 228                         if (exclusive) {                                \
 229                                 abort_exclusive_wait(&wq, &__wait,      \
 230                                                      state, NULL);      \
 231                                 goto __out;                             \
 232                         }                                               \
 233                         break;                                          \
 234                 }                                                       \
 235                                                                         \
 236                 cmd;                                                    \
 237         }                                                               \
 238         finish_wait(&wq, &__wait);                                      \
 239 __out:  __ret;                                                          \
 240 })
 241
 242 #define __wait_event(wq, condition)                                     \
 243         (void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0, 0,  \
 244                             schedule())
 245
 246 /**
 247  * wait_event - sleep until a condition gets true
 248  * @wq: the waitqueue to wait on
 249  * @condition: a C expression for the event to wait for
 250  *
 251  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 252  * @condition evaluates to true. The @condition is checked each time
 253  * the waitqueue @wq is woken up.
 254  *
 255  * wake_up() has to be called after changing any variable that could
 256  * change the result of the wait condition.
 257  */
 258 #define wait_event(wq, condition)                                       \
 259 do {                                                                    \
 260         if (condition)                                                  \
 261                 break;                                                  \
 262         __wait_event(wq, condition);                                    \
 263 } while (0)
 264
 265 #define __wait_event_timeout(wq, condition, timeout)                    \
 266         ___wait_event(wq, ___wait_cond_timeout(condition),              \
 267                       TASK_UNINTERRUPTIBLE, 0, timeout,                 \
 268                       __ret = schedule_timeout(__ret))
 269
 270 /**
 271  * wait_event_timeout - sleep until a condition gets true or a timeout elapses
 272  * @wq: the waitqueue to wait on
 273  * @condition: a C expression for the event to wait for
 274  * @timeout: timeout, in jiffies
 275  *
 276  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 277  * @condition evaluates to true. The @condition is checked each time
 278  * the waitqueue @wq is woken up.
 279  *
 280  * wake_up() has to be called after changing any variable that could
 281  * change the result of the wait condition.
 282  *
 283  * The function returns 0 if the @timeout elapsed, or the remaining
 284  * jiffies (at least 1) if the @condition evaluated to %true before
 285  * the @timeout elapsed.
 286  */
 287 #define wait_event_timeout(wq, condition, timeout)                      \
 288 ({                                                                      \
 289         long __ret = timeout;                                           \
 290         if (!___wait_cond_timeout(condition))                           \
 291                 __ret = __wait_event_timeout(wq, condition, timeout);   \
 292         __ret;                                                          \
 293 })
 294
 295 #define __wait_event_cmd(wq, condition, cmd1, cmd2)                     \
 296         (void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0, 0,  \
 297                             cmd1; schedule(); cmd2)
 298
 299 /**
 300  * wait_event_cmd - sleep until a condition gets true
 301  * @wq: the waitqueue to wait on
 302  * @condition: a C expression for the event to wait for
 303  * @cmd1: the command will be executed before sleep
 304  * @cmd2: the command will be executed after sleep
 305  *
 306  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 307  * @condition evaluates to true. The @condition is checked each time
 308  * the waitqueue @wq is woken up.
 309  *
 310  * wake_up() has to be called after changing any variable that could
 311  * change the result of the wait condition.
 312  */
 313 #define wait_event_cmd(wq, condition, cmd1, cmd2)                       \
 314 do {                                                                    \
 315         if (condition)                                                  \
 316                 break;                                                  \
 317         __wait_event_cmd(wq, condition, cmd1, cmd2);                    \
 318 } while (0)
 319
 320 #define __wait_event_interruptible(wq, condition)                       \
 321         ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 0, 0,          \
 322                       schedule())
 323
 324 /**
 325  * wait_event_interruptible - sleep until a condition gets true
 326  * @wq: the waitqueue to wait on
 327  * @condition: a C expression for the event to wait for
 328  *
 329  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 330  * @condition evaluates to true or a signal is received.
 331  * The @condition is checked each time the waitqueue @wq is woken up.
 332  *
 333  * wake_up() has to be called after changing any variable that could
 334  * change the result of the wait condition.
 335  *
 336  * The function will return -ERESTARTSYS if it was interrupted by a
 337  * signal and 0 if @condition evaluated to true.
 338  */
 339 #define wait_event_interruptible(wq, condition)                         \
 340 ({                                                                      \
 341         int __ret = 0;                                                  \
 342         if (!(condition))                                               \
 343                 __ret = __wait_event_interruptible(wq, condition);      \
 344         __ret;                                                          \
 345 })
 346
 347 #define __wait_event_interruptible_timeout(wq, condition, timeout)      \
 348         ___wait_event(wq, ___wait_cond_timeout(condition),              \
 349                       TASK_INTERRUPTIBLE, 0, timeout,                   \
 350                       __ret = schedule_timeout(__ret))
 351
 352 /**
 353  * wait_event_interruptible_timeout - sleep until a condition gets true or a timeout elapses
 354  * @wq: the waitqueue to wait on
 355  * @condition: a C expression for the event to wait for
 356  * @timeout: timeout, in jiffies
 357  *
 358  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 359  * @condition evaluates to true or a signal is received.
 360  * The @condition is checked each time the waitqueue @wq is woken up.
 361  *
 362  * wake_up() has to be called after changing any variable that could
 363  * change the result of the wait condition.
 364  *
 365  * Returns:
 366  * 0 if the @timeout elapsed, -%ERESTARTSYS if it was interrupted by
 367  * a signal, or the remaining jiffies (at least 1) if the @condition
 368  * evaluated to %true before the @timeout elapsed.
 369  */
 370 #define wait_event_interruptible_timeout(wq, condition, timeout)        \
 371 ({                                                                      \
 372         long __ret = timeout;                                           \
 373         if (!___wait_cond_timeout(condition))                           \
 374                 __ret = __wait_event_interruptible_timeout(wq,          \
 375                                                 condition, timeout);    \
 376         __ret;                                                          \
 377 })
 378
 379 #define __wait_event_hrtimeout(wq, condition, timeout, state)           \
 380 ({                                                                      \
 381         int __ret = 0;                                                  \
 382         struct hrtimer_sleeper __t;                                     \
 383                                                                         \
 384         hrtimer_init_on_stack(&__t.timer, CLOCK_MONOTONIC,              \
 385                               HRTIMER_MODE_REL);                        \
 386         hrtimer_init_sleeper(&__t, current);                            \
 387         if ((timeout).tv64 != KTIME_MAX)                                \
 388                 hrtimer_start_range_ns(&__t.timer, timeout,             \
 389                                        current->timer_slack_ns,         \
 390                                        HRTIMER_MODE_REL);               \
 391                                                                         \
 392         __ret = ___wait_event(wq, condition, state, 0, 0,               \
 393                 if (!__t.task) {                                        \
 394                         __ret = -ETIME;                                 \
 395                         break;                                          \
 396                 }                                                       \
 397                 schedule());                                            \
 398                                                                         \
 399         hrtimer_cancel(&__t.timer);                                     \
 400         destroy_hrtimer_on_stack(&__t.timer);                           \
 401         __ret;                                                          \
 402 })
 403
 404 /**
 405  * wait_event_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_UNINTERRUPTIBLE) 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, or -ETIME if the timeout
 418  * elapsed.
 419  */
 420 #define wait_event_hrtimeout(wq, condition, timeout)                    \
 421 ({                                                                      \
 422         int __ret = 0;                                                  \
 423         if (!(condition))                                               \
 424                 __ret = __wait_event_hrtimeout(wq, condition, timeout,  \
 425                                                TASK_UNINTERRUPTIBLE);   \
 426         __ret;                                                          \
 427 })
 428
 429 /**
 430  * wait_event_interruptible_hrtimeout - sleep until a condition gets true or a timeout elapses
 431  * @wq: the waitqueue to wait on
 432  * @condition: a C expression for the event to wait for
 433  * @timeout: timeout, as a ktime_t
 434  *
 435  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 436  * @condition evaluates to true or a signal is received.
 437  * The @condition is checked each time the waitqueue @wq is woken up.
 438  *
 439  * wake_up() has to be called after changing any variable that could
 440  * change the result of the wait condition.
 441  *
 442  * The function returns 0 if @condition became true, -ERESTARTSYS if it was
 443  * interrupted by a signal, or -ETIME if the timeout elapsed.
 444  */
 445 #define wait_event_interruptible_hrtimeout(wq, condition, timeout)      \
 446 ({                                                                      \
 447         long __ret = 0;                                                 \
 448         if (!(condition))                                               \
 449                 __ret = __wait_event_hrtimeout(wq, condition, timeout,  \
 450                                                TASK_INTERRUPTIBLE);     \
 451         __ret;                                                          \
 452 })
 453
 454 #define __wait_event_interruptible_exclusive(wq, condition)             \
 455         ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 1, 0,          \
 456                       schedule())
 457
 458 #define wait_event_interruptible_exclusive(wq, condition)               \
 459 ({                                                                      \
 460         int __ret = 0;                                                  \
 461         if (!(condition))                                               \
 462                 __ret = __wait_event_interruptible_exclusive(wq, condition);\
 463         __ret;                                                          \
 464 })
 465
 466
 467 #define __wait_event_interruptible_locked(wq, condition, exclusive, irq) \
 468 ({                                                                      \
 469         int __ret = 0;                                                  \
 470         DEFINE_WAIT(__wait);                                            \
 471         if (exclusive)                                                  \
 472                 __wait.flags |= WQ_FLAG_EXCLUSIVE;                      \
 473         do {                                                            \
 474                 if (likely(list_empty(&__wait.task_list)))              \
 475                         __add_wait_queue_tail(&(wq), &__wait);          \
 476                 set_current_state(TASK_INTERRUPTIBLE);                  \
 477                 if (signal_pending(current)) {                          \
 478                         __ret = -ERESTARTSYS;                           \
 479                         break;                                          \
 480                 }                                                       \
 481                 if (irq)                                                \
 482                         spin_unlock_irq(&(wq).lock);                    \
 483                 else                                                    \
 484                         spin_unlock(&(wq).lock);                        \
 485                 schedule();                                             \
 486                 if (irq)                                                \
 487                         spin_lock_irq(&(wq).lock);                      \
 488                 else                                                    \
 489                         spin_lock(&(wq).lock);                          \
 490         } while (!(condition));                                         \
 491         __remove_wait_queue(&(wq), &__wait);                            \
 492         __set_current_state(TASK_RUNNING);                              \
 493         __ret;                                                          \
 494 })
 495
 496
 497 /**
 498  * wait_event_interruptible_locked - sleep until a condition gets true
 499  * @wq: the waitqueue to wait on
 500  * @condition: a C expression for the event to wait for
 501  *
 502  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 503  * @condition evaluates to true or a signal is received.
 504  * The @condition is checked each time the waitqueue @wq is woken up.
 505  *
 506  * It must be called with wq.lock being held.  This spinlock is
 507  * unlocked while sleeping but @condition testing is done while lock
 508  * is held and when this macro exits the lock is held.
 509  *
 510  * The lock is locked/unlocked using spin_lock()/spin_unlock()
 511  * functions which must match the way they are locked/unlocked outside
 512  * of this macro.
 513  *
 514  * wake_up_locked() has to be called after changing any variable that could
 515  * change the result of the wait condition.
 516  *
 517  * The function will return -ERESTARTSYS if it was interrupted by a
 518  * signal and 0 if @condition evaluated to true.
 519  */
 520 #define wait_event_interruptible_locked(wq, condition)                  \
 521         ((condition)                                                    \
 522          ? 0 : __wait_event_interruptible_locked(wq, condition, 0, 0))
 523
 524 /**
 525  * wait_event_interruptible_locked_irq - sleep until a condition gets true
 526  * @wq: the waitqueue to wait on
 527  * @condition: a C expression for the event to wait for
 528  *
 529  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 530  * @condition evaluates to true or a signal is received.
 531  * The @condition is checked each time the waitqueue @wq is woken up.
 532  *
 533  * It must be called with wq.lock being held.  This spinlock is
 534  * unlocked while sleeping but @condition testing is done while lock
 535  * is held and when this macro exits the lock is held.
 536  *
 537  * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq()
 538  * functions which must match the way they are locked/unlocked outside
 539  * of this macro.
 540  *
 541  * wake_up_locked() has to be called after changing any variable that could
 542  * change the result of the wait condition.
 543  *
 544  * The function will return -ERESTARTSYS if it was interrupted by a
 545  * signal and 0 if @condition evaluated to true.
 546  */
 547 #define wait_event_interruptible_locked_irq(wq, condition)              \
 548         ((condition)                                                    \
 549          ? 0 : __wait_event_interruptible_locked(wq, condition, 0, 1))
 550
 551 /**
 552  * wait_event_interruptible_exclusive_locked - sleep exclusively until a condition gets true
 553  * @wq: the waitqueue to wait on
 554  * @condition: a C expression for the event to wait for
 555  *
 556  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 557  * @condition evaluates to true or a signal is received.
 558  * The @condition is checked each time the waitqueue @wq is woken up.
 559  *
 560  * It must be called with wq.lock being held.  This spinlock is
 561  * unlocked while sleeping but @condition testing is done while lock
 562  * is held and when this macro exits the lock is held.
 563  *
 564  * The lock is locked/unlocked using spin_lock()/spin_unlock()
 565  * functions which must match the way they are locked/unlocked outside
 566  * of this macro.
 567  *
 568  * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
 569  * set thus when other process waits process on the list if this
 570  * process is awaken further processes are not considered.
 571  *
 572  * wake_up_locked() has to be called after changing any variable that could
 573  * change the result of the wait condition.
 574  *
 575  * The function will return -ERESTARTSYS if it was interrupted by a
 576  * signal and 0 if @condition evaluated to true.
 577  */
 578 #define wait_event_interruptible_exclusive_locked(wq, condition)        \
 579         ((condition)                                                    \
 580          ? 0 : __wait_event_interruptible_locked(wq, condition, 1, 0))
 581
 582 /**
 583  * wait_event_interruptible_exclusive_locked_irq - sleep until a condition gets true
 584  * @wq: the waitqueue to wait on
 585  * @condition: a C expression for the event to wait for
 586  *
 587  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 588  * @condition evaluates to true or a signal is received.
 589  * The @condition is checked each time the waitqueue @wq is woken up.
 590  *
 591  * It must be called with wq.lock being held.  This spinlock is
 592  * unlocked while sleeping but @condition testing is done while lock
 593  * is held and when this macro exits the lock is held.
 594  *
 595  * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq()
 596  * functions which must match the way they are locked/unlocked outside
 597  * of this macro.
 598  *
 599  * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
 600  * set thus when other process waits process on the list if this
 601  * process is awaken further processes are not considered.
 602  *
 603  * wake_up_locked() has to be called after changing any variable that could
 604  * change the result of the wait condition.
 605  *
 606  * The function will return -ERESTARTSYS if it was interrupted by a
 607  * signal and 0 if @condition evaluated to true.
 608  */
 609 #define wait_event_interruptible_exclusive_locked_irq(wq, condition)    \
 610         ((condition)                                                    \
 611          ? 0 : __wait_event_interruptible_locked(wq, condition, 1, 1))
 612
 613
 614 #define __wait_event_killable(wq, condition)                            \
 615         ___wait_event(wq, condition, TASK_KILLABLE, 0, 0, schedule())
 616
 617 /**
 618  * wait_event_killable - sleep until a condition gets true
 619  * @wq: the waitqueue to wait on
 620  * @condition: a C expression for the event to wait for
 621  *
 622  * The process is put to sleep (TASK_KILLABLE) until the
 623  * @condition evaluates to true or a signal is received.
 624  * The @condition is checked each time the waitqueue @wq is woken up.
 625  *
 626  * wake_up() has to be called after changing any variable that could
 627  * change the result of the wait condition.
 628  *
 629  * The function will return -ERESTARTSYS if it was interrupted by a
 630  * signal and 0 if @condition evaluated to true.
 631  */
 632 #define wait_event_killable(wq, condition)                              \
 633 ({                                                                      \
 634         int __ret = 0;                                                  \
 635         if (!(condition))                                               \
 636                 __ret = __wait_event_killable(wq, condition);           \
 637         __ret;                                                          \
 638 })
 639
 640
 641 #define __wait_event_lock_irq(wq, condition, lock, cmd)                 \
 642         (void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0, 0,  \
 643                             spin_unlock_irq(&lock);                     \
 644                             cmd;                                        \
 645                             schedule();                                 \
 646                             spin_lock_irq(&lock))
 647
 648 /**
 649  * wait_event_lock_irq_cmd - sleep until a condition gets true. The
 650  *                           condition is checked under the lock. This
 651  *                           is expected to be called with the lock
 652  *                           taken.
 653  * @wq: the waitqueue to wait on
 654  * @condition: a C expression for the event to wait for
 655  * @lock: a locked spinlock_t, which will be released before cmd
 656  *        and schedule() and reacquired afterwards.
 657  * @cmd: a command which is invoked outside the critical section before
 658  *       sleep
 659  *
 660  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 661  * @condition evaluates to true. The @condition is checked each time
 662  * the waitqueue @wq is woken up.
 663  *
 664  * wake_up() has to be called after changing any variable that could
 665  * change the result of the wait condition.
 666  *
 667  * This is supposed to be called while holding the lock. The lock is
 668  * dropped before invoking the cmd and going to sleep and is reacquired
 669  * afterwards.
 670  */
 671 #define wait_event_lock_irq_cmd(wq, condition, lock, cmd)               \
 672 do {                                                                    \
 673         if (condition)                                                  \
 674                 break;                                                  \
 675         __wait_event_lock_irq(wq, condition, lock, cmd);                \
 676 } while (0)
 677
 678 /**
 679  * wait_event_lock_irq - sleep until a condition gets true. The
 680  *                       condition is checked under the lock. This
 681  *                       is expected to be called with the lock
 682  *                       taken.
 683  * @wq: the waitqueue to wait on
 684  * @condition: a C expression for the event to wait for
 685  * @lock: a locked spinlock_t, which will be released before schedule()
 686  *        and reacquired afterwards.
 687  *
 688  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 689  * @condition evaluates to true. The @condition is checked each time
 690  * the waitqueue @wq is woken up.
 691  *
 692  * wake_up() has to be called after changing any variable that could
 693  * change the result of the wait condition.
 694  *
 695  * This is supposed to be called while holding the lock. The lock is
 696  * dropped before going to sleep and is reacquired afterwards.
 697  */
 698 #define wait_event_lock_irq(wq, condition, lock)                        \
 699 do {                                                                    \
 700         if (condition)                                                  \
 701                 break;                                                  \
 702         __wait_event_lock_irq(wq, condition, lock, );                   \
 703 } while (0)
 704
 705
 706 #define __wait_event_interruptible_lock_irq(wq, condition, lock, cmd)   \
 707         ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 0, 0,          \
 708                       spin_unlock_irq(&lock);                           \
 709                       cmd;                                              \
 710                       schedule();                                       \
 711                       spin_lock_irq(&lock))
 712
 713 /**
 714  * wait_event_interruptible_lock_irq_cmd - sleep until a condition gets true.
 715  *              The condition is checked under the lock. This is expected to
 716  *              be called with the lock taken.
 717  * @wq: the waitqueue to wait on
 718  * @condition: a C expression for the event to wait for
 719  * @lock: a locked spinlock_t, which will be released before cmd and
 720  *        schedule() and reacquired afterwards.
 721  * @cmd: a command which is invoked outside the critical section before
 722  *       sleep
 723  *
 724  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 725  * @condition evaluates to true or a signal is received. The @condition is
 726  * checked each time the waitqueue @wq is woken up.
 727  *
 728  * wake_up() has to be called after changing any variable that could
 729  * change the result of the wait condition.
 730  *
 731  * This is supposed to be called while holding the lock. The lock is
 732  * dropped before invoking the cmd and going to sleep and is reacquired
 733  * afterwards.
 734  *
 735  * The macro will return -ERESTARTSYS if it was interrupted by a signal
 736  * and 0 if @condition evaluated to true.
 737  */
 738 #define wait_event_interruptible_lock_irq_cmd(wq, condition, lock, cmd) \
 739 ({                                                                      \
 740         int __ret = 0;                                                  \
 741         if (!(condition))                                               \
 742                 __ret = __wait_event_interruptible_lock_irq(wq,         \
 743                                                 condition, lock, cmd);  \
 744         __ret;                                                          \
 745 })
 746
 747 /**
 748  * wait_event_interruptible_lock_irq - sleep until a condition gets true.
 749  *              The condition is checked under the lock. This is expected
 750  *              to be called with the lock taken.
 751  * @wq: the waitqueue to wait on
 752  * @condition: a C expression for the event to wait for
 753  * @lock: a locked spinlock_t, which will be released before schedule()
 754  *        and reacquired afterwards.
 755  *
 756  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 757  * @condition evaluates to true or 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 going to sleep and is reacquired afterwards.
 765  *
 766  * The macro will return -ERESTARTSYS if it was interrupted by a signal
 767  * and 0 if @condition evaluated to true.
 768  */
 769 #define wait_event_interruptible_lock_irq(wq, condition, lock)          \
 770 ({                                                                      \
 771         int __ret = 0;                                                  \
 772         if (!(condition))                                               \
 773                 __ret = __wait_event_interruptible_lock_irq(wq,         \
 774                                                 condition, lock,);      \
 775         __ret;                                                          \
 776 })
 777
 778 #define __wait_event_interruptible_lock_irq_timeout(wq, condition,      \
 779                                                     lock, timeout)      \
 780         ___wait_event(wq, ___wait_cond_timeout(condition),              \
 781                       TASK_INTERRUPTIBLE, 0, timeout,                   \
 782                       spin_unlock_irq(&lock);                           \
 783                       __ret = schedule_timeout(__ret);                  \
 784                       spin_lock_irq(&lock));
 785
 786 /**
 787  * wait_event_interruptible_lock_irq_timeout - sleep until a condition gets
 788  *              true or a timeout elapses. The condition is checked under
 789  *              the lock. This is expected to be called with the lock taken.
 790  * @wq: the waitqueue to wait on
 791  * @condition: a C expression for the event to wait for
 792  * @lock: a locked spinlock_t, which will be released before schedule()
 793  *        and reacquired afterwards.
 794  * @timeout: timeout, in jiffies
 795  *
 796  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 797  * @condition evaluates to true or signal is received. The @condition is
 798  * checked each time the waitqueue @wq is woken up.
 799  *
 800  * wake_up() has to be called after changing any variable that could
 801  * change the result of the wait condition.
 802  *
 803  * This is supposed to be called while holding the lock. The lock is
 804  * dropped before going to sleep and is reacquired afterwards.
 805  *
 806  * The function returns 0 if the @timeout elapsed, -ERESTARTSYS if it
 807  * was interrupted by a signal, and the remaining jiffies otherwise
 808  * if the condition evaluated to true before the timeout elapsed.
 809  */
 810 #define wait_event_interruptible_lock_irq_timeout(wq, condition, lock,  \
 811                                                   timeout)              \
 812 ({                                                                      \
 813         long __ret = timeout;                                           \
 814         if (!___wait_cond_timeout(condition))                           \
 815                 __ret = __wait_event_interruptible_lock_irq_timeout(    \
 816                                         wq, condition, lock, timeout);  \
 817         __ret;                                                          \
 818 })
 819
 820 /*
 821  * Waitqueues which are removed from the waitqueue_head at wakeup time
 822  */
 823 void prepare_to_wait(wait_queue_head_t *q, wait_queue_t *wait, int state);
 824 void prepare_to_wait_exclusive(wait_queue_head_t *q, wait_queue_t *wait, int state);
 825 long prepare_to_wait_event(wait_queue_head_t *q, wait_queue_t *wait, int state);
 826 void finish_wait(wait_queue_head_t *q, wait_queue_t *wait);
 827 void abort_exclusive_wait(wait_queue_head_t *q, wait_queue_t *wait, unsigned int mode, void *key);
 828 int autoremove_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 829 int wake_bit_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 830
 831 #define DEFINE_WAIT_FUNC(name, function)                                \
 832         wait_queue_t name = {                                           \
 833                 .private        = current,                              \
 834                 .func           = function,                             \
 835                 .task_list      = LIST_HEAD_INIT((name).task_list),     \
 836         }
 837
 838 #define DEFINE_WAIT(name) DEFINE_WAIT_FUNC(name, autoremove_wake_function)
 839
 840 #define DEFINE_WAIT_BIT(name, word, bit)                                \
 841         struct wait_bit_queue name = {                                  \
 842                 .key = __WAIT_BIT_KEY_INITIALIZER(word, bit),           \
 843                 .wait   = {                                             \
 844                         .private        = current,                      \
 845                         .func           = wake_bit_function,            \
 846                         .task_list      =                               \
 847                                 LIST_HEAD_INIT((name).wait.task_list),  \
 848                 },                                                      \
 849         }
 850
 851 #define init_wait(wait)                                                 \
 852         do {                                                            \
 853                 (wait)->private = current;                              \
 854                 (wait)->func = autoremove_wake_function;                \
 855                 INIT_LIST_HEAD(&(wait)->task_list);                     \
 856                 (wait)->flags = 0;                                      \
 857         } while (0)
 858
 859
 860 extern int bit_wait(struct wait_bit_key *);
 861 extern int bit_wait_io(struct wait_bit_key *);
 862
 863 /**
 864  * wait_on_bit - wait for a bit to be cleared
 865  * @word: the word being waited on, a kernel virtual address
 866  * @bit: the bit of the word being waited on
 867  * @mode: the task state to sleep in
 868  *
 869  * There is a standard hashed waitqueue table for generic use. This
 870  * is the part of the hashtable's accessor API that waits on a bit.
 871  * For instance, if one were to have waiters on a bitflag, one would
 872  * call wait_on_bit() in threads waiting for the bit to clear.
 873  * One uses wait_on_bit() where one is waiting for the bit to clear,
 874  * but has no intention of setting it.
 875  * Returned value will be zero if the bit was cleared, or non-zero
 876  * if the process received a signal and the mode permitted wakeup
 877  * on that signal.
 878  */
 879 static inline int
 880 wait_on_bit(void *word, int bit, unsigned mode)
 881 {
 882         if (!test_bit(bit, word))
 883                 return 0;
 884         return out_of_line_wait_on_bit(word, bit,
 885                                        bit_wait,
 886                                        mode);
 887 }
 888
 889 /**
 890  * wait_on_bit_io - wait for a bit to be cleared
 891  * @word: the word being waited on, a kernel virtual address
 892  * @bit: the bit of the word being waited on
 893  * @mode: the task state to sleep in
 894  *
 895  * Use the standard hashed waitqueue table to wait for a bit
 896  * to be cleared.  This is similar to wait_on_bit(), but calls
 897  * io_schedule() instead of schedule() for the actual waiting.
 898  *
 899  * Returned value will be zero if the bit was cleared, or non-zero
 900  * if the process received a signal and the mode permitted wakeup
 901  * on that signal.
 902  */
 903 static inline int
 904 wait_on_bit_io(void *word, int bit, unsigned mode)
 905 {
 906         if (!test_bit(bit, word))
 907                 return 0;
 908         return out_of_line_wait_on_bit(word, bit,
 909                                        bit_wait_io,
 910                                        mode);
 911 }
 912
 913 /**
 914  * wait_on_bit_action - wait for a bit to be cleared
 915  * @word: the word being waited on, a kernel virtual address
 916  * @bit: the bit of the word being waited on
 917  * @action: the function used to sleep, which may take special actions
 918  * @mode: the task state to sleep in
 919  *
 920  * Use the standard hashed waitqueue table to wait for a bit
 921  * to be cleared, and allow the waiting action to be specified.
 922  * This is like wait_on_bit() but allows fine control of how the waiting
 923  * is done.
 924  *
 925  * Returned value will be zero if the bit was cleared, or non-zero
 926  * if the process received a signal and the mode permitted wakeup
 927  * on that signal.
 928  */
 929 static inline int
 930 wait_on_bit_action(void *word, int bit, wait_bit_action_f *action, unsigned mode)
 931 {
 932         if (!test_bit(bit, word))
 933                 return 0;
 934         return out_of_line_wait_on_bit(word, bit, action, mode);
 935 }
 936
 937 /**
 938  * wait_on_bit_lock - wait for a bit to be cleared, when wanting to set it
 939  * @word: the word being waited on, a kernel virtual address
 940  * @bit: the bit of the word being waited on
 941  * @mode: the task state to sleep in
 942  *
 943  * There is a standard hashed waitqueue table for generic use. This
 944  * is the part of the hashtable's accessor API that waits on a bit
 945  * when one intends to set it, for instance, trying to lock bitflags.
 946  * For instance, if one were to have waiters trying to set bitflag
 947  * and waiting for it to clear before setting it, one would call
 948  * wait_on_bit() in threads waiting to be able to set the bit.
 949  * One uses wait_on_bit_lock() where one is waiting for the bit to
 950  * clear with the intention of setting it, and when done, clearing it.
 951  *
 952  * Returns zero if the bit was (eventually) found to be clear and was
 953  * set.  Returns non-zero if a signal was delivered to the process and
 954  * the @mode allows that signal to wake the process.
 955  */
 956 static inline int
 957 wait_on_bit_lock(void *word, int bit, unsigned mode)
 958 {
 959         if (!test_and_set_bit(bit, word))
 960                 return 0;
 961         return out_of_line_wait_on_bit_lock(word, bit, bit_wait, mode);
 962 }
 963
 964 /**
 965  * wait_on_bit_lock_io - wait for a bit to be cleared, when wanting to set it
 966  * @word: the word being waited on, a kernel virtual address
 967  * @bit: the bit of the word being waited on
 968  * @mode: the task state to sleep in
 969  *
 970  * Use the standard hashed waitqueue table to wait for a bit
 971  * to be cleared and then to atomically set it.  This is similar
 972  * to wait_on_bit(), but calls io_schedule() instead of schedule()
 973  * for the actual waiting.
 974  *
 975  * Returns zero if the bit was (eventually) found to be clear and was
 976  * set.  Returns non-zero if a signal was delivered to the process and
 977  * the @mode allows that signal to wake the process.
 978  */
 979 static inline int
 980 wait_on_bit_lock_io(void *word, int bit, unsigned mode)
 981 {
 982         if (!test_and_set_bit(bit, word))
 983                 return 0;
 984         return out_of_line_wait_on_bit_lock(word, bit, bit_wait_io, mode);
 985 }
 986
 987 /**
 988  * wait_on_bit_lock_action - wait for a bit to be cleared, when wanting to set it
 989  * @word: the word being waited on, a kernel virtual address
 990  * @bit: the bit of the word being waited on
 991  * @action: the function used to sleep, which may take special actions
 992  * @mode: the task state to sleep in
 993  *
 994  * Use the standard hashed waitqueue table to wait for a bit
 995  * to be cleared and then to set it, and allow the waiting action
 996  * to be specified.
 997  * This is like wait_on_bit() but allows fine control of how the waiting
 998  * is done.
 999  *
1000  * Returns zero if the bit was (eventually) found to be clear and was
1001  * set.  Returns non-zero if a signal was delivered to the process and
1002  * the @mode allows that signal to wake the process.
1003  */
1004 static inline int
1005 wait_on_bit_lock_action(void *word, int bit, wait_bit_action_f *action, unsigned mode)
1006 {
1007         if (!test_and_set_bit(bit, word))
1008                 return 0;
1009         return out_of_line_wait_on_bit_lock(word, bit, action, mode);
1010 }
1011
1012 /**
1013  * wait_on_atomic_t - Wait for an atomic_t to become 0
1014  * @val: The atomic value being waited on, a kernel virtual address
1015  * @action: the function used to sleep, which may take special actions
1016  * @mode: the task state to sleep in
1017  *
1018  * Wait for an atomic_t to become 0.  We abuse the bit-wait waitqueue table for
1019  * the purpose of getting a waitqueue, but we set the key to a bit number
1020  * outside of the target 'word'.
1021  */
1022 static inline
1023 int wait_on_atomic_t(atomic_t *val, int (*action)(atomic_t *), unsigned mode)
1024 {
1025         if (atomic_read(val) == 0)
1026                 return 0;
1027         return out_of_line_wait_on_atomic_t(val, action, mode);
1028 }
1029
1030 #endif /* _LINUX_WAIT_H */