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 };
  29
  30 struct wait_bit_queue {
  31         struct wait_bit_key     key;
  32         wait_queue_t            wait;
  33 };
  34
  35 struct __wait_queue_head {
  36         spinlock_t              lock;
  37         struct list_head        task_list;
  38 };
  39 typedef struct __wait_queue_head wait_queue_head_t;
  40
  41 struct task_struct;
  42
  43 /*
  44  * Macros for declaration and initialisaton of the datatypes
  45  */
  46
  47 #define __WAITQUEUE_INITIALIZER(name, tsk) {                            \
  48         .private        = tsk,                                          \
  49         .func           = default_wake_function,                        \
  50         .task_list      = { NULL, NULL } }
  51
  52 #define DECLARE_WAITQUEUE(name, tsk)                                    \
  53         wait_queue_t name = __WAITQUEUE_INITIALIZER(name, tsk)
  54
  55 #define __WAIT_QUEUE_HEAD_INITIALIZER(name) {                           \
  56         .lock           = __SPIN_LOCK_UNLOCKED(name.lock),              \
  57         .task_list      = { &(name).task_list, &(name).task_list } }
  58
  59 #define DECLARE_WAIT_QUEUE_HEAD(name) \
  60         wait_queue_head_t name = __WAIT_QUEUE_HEAD_INITIALIZER(name)
  61
  62 #define __WAIT_BIT_KEY_INITIALIZER(word, bit)                           \
  63         { .flags = word, .bit_nr = bit, }
  64
  65 #define __WAIT_ATOMIC_T_KEY_INITIALIZER(p)                              \
  66         { .flags = p, .bit_nr = WAIT_ATOMIC_T_BIT_NR, }
  67
  68 extern void __init_waitqueue_head(wait_queue_head_t *q, const char *name, struct lock_class_key *);
  69
  70 #define init_waitqueue_head(q)                          \
  71         do {                                            \
  72                 static struct lock_class_key __key;     \
  73                                                         \
  74                 __init_waitqueue_head((q), #q, &__key); \
  75         } while (0)
  76
  77 #ifdef CONFIG_LOCKDEP
  78 # define __WAIT_QUEUE_HEAD_INIT_ONSTACK(name) \
  79         ({ init_waitqueue_head(&name); name; })
  80 # define DECLARE_WAIT_QUEUE_HEAD_ONSTACK(name) \
  81         wait_queue_head_t name = __WAIT_QUEUE_HEAD_INIT_ONSTACK(name)
  82 #else
  83 # define DECLARE_WAIT_QUEUE_HEAD_ONSTACK(name) DECLARE_WAIT_QUEUE_HEAD(name)
  84 #endif
  85
  86 static inline void init_waitqueue_entry(wait_queue_t *q, struct task_struct *p)
  87 {
  88         q->flags        = 0;
  89         q->private      = p;
  90         q->func         = default_wake_function;
  91 }
  92
  93 static inline void
  94 init_waitqueue_func_entry(wait_queue_t *q, wait_queue_func_t func)
  95 {
  96         q->flags        = 0;
  97         q->private      = NULL;
  98         q->func         = func;
  99 }
 100
 101 static inline int waitqueue_active(wait_queue_head_t *q)
 102 {
 103         return !list_empty(&q->task_list);
 104 }
 105
 106 extern void add_wait_queue(wait_queue_head_t *q, wait_queue_t *wait);
 107 extern void add_wait_queue_exclusive(wait_queue_head_t *q, wait_queue_t *wait);
 108 extern void remove_wait_queue(wait_queue_head_t *q, wait_queue_t *wait);
 109
 110 static inline void __add_wait_queue(wait_queue_head_t *head, wait_queue_t *new)
 111 {
 112         list_add(&new->task_list, &head->task_list);
 113 }
 114
 115 /*
 116  * Used for wake-one threads:
 117  */
 118 static inline void
 119 __add_wait_queue_exclusive(wait_queue_head_t *q, wait_queue_t *wait)
 120 {
 121         wait->flags |= WQ_FLAG_EXCLUSIVE;
 122         __add_wait_queue(q, wait);
 123 }
 124
 125 static inline void __add_wait_queue_tail(wait_queue_head_t *head,
 126                                          wait_queue_t *new)
 127 {
 128         list_add_tail(&new->task_list, &head->task_list);
 129 }
 130
 131 static inline void
 132 __add_wait_queue_tail_exclusive(wait_queue_head_t *q, wait_queue_t *wait)
 133 {
 134         wait->flags |= WQ_FLAG_EXCLUSIVE;
 135         __add_wait_queue_tail(q, wait);
 136 }
 137
 138 static inline void
 139 __remove_wait_queue(wait_queue_head_t *head, wait_queue_t *old)
 140 {
 141         list_del(&old->task_list);
 142 }
 143
 144 void __wake_up(wait_queue_head_t *q, unsigned int mode, int nr, void *key);
 145 void __wake_up_locked_key(wait_queue_head_t *q, unsigned int mode, void *key);
 146 void __wake_up_sync_key(wait_queue_head_t *q, unsigned int mode, int nr, 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_is_interruptible(state)                                 \
 191         (!__builtin_constant_p(state) ||                                \
 192                 state == TASK_INTERRUPTIBLE || state == TASK_KILLABLE)  \
 193
 194 /*
 195  * The below macro ___wait_event() has an explicit shadow of the __ret
 196  * variable when used from the wait_event_*() macros.
 197  *
 198  * This is so that both can use the ___wait_cond_timeout() construct
 199  * to wrap the condition.
 200  *
 201  * The type inconsistency of the wait_event_*() __ret variable is also
 202  * on purpose; we use long where we can return timeout values and int
 203  * otherwise.
 204  */
 205
 206 #define ___wait_event(wq, condition, state, exclusive, ret, cmd)        \
 207 ({                                                                      \
 208         __label__ __out;                                                \
 209         wait_queue_t __wait;                                            \
 210         long __ret = ret;       /* explicit shadow */                   \
 211                                                                         \
 212         INIT_LIST_HEAD(&__wait.task_list);                              \
 213         if (exclusive)                                                  \
 214                 __wait.flags = WQ_FLAG_EXCLUSIVE;                       \
 215         else                                                            \
 216                 __wait.flags = 0;                                       \
 217                                                                         \
 218         for (;;) {                                                      \
 219                 long __int = prepare_to_wait_event(&wq, &__wait, state);\
 220                                                                         \
 221                 if (condition)                                          \
 222                         break;                                          \
 223                                                                         \
 224                 if (___wait_is_interruptible(state) && __int) {         \
 225                         __ret = __int;                                  \
 226                         if (exclusive) {                                \
 227                                 abort_exclusive_wait(&wq, &__wait,      \
 228                                                      state, NULL);      \
 229                                 goto __out;                             \
 230                         }                                               \
 231                         break;                                          \
 232                 }                                                       \
 233                                                                         \
 234                 cmd;                                                    \
 235         }                                                               \
 236         finish_wait(&wq, &__wait);                                      \
 237 __out:  __ret;                                                          \
 238 })
 239
 240 #define __wait_event(wq, condition)                                     \
 241         (void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0, 0,  \
 242                             schedule())
 243
 244 /**
 245  * wait_event - sleep until a condition gets true
 246  * @wq: the waitqueue to wait on
 247  * @condition: a C expression for the event to wait for
 248  *
 249  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 250  * @condition evaluates to true. The @condition is checked each time
 251  * the waitqueue @wq is woken up.
 252  *
 253  * wake_up() has to be called after changing any variable that could
 254  * change the result of the wait condition.
 255  */
 256 #define wait_event(wq, condition)                                       \
 257 do {                                                                    \
 258         if (condition)                                                  \
 259                 break;                                                  \
 260         __wait_event(wq, condition);                                    \
 261 } while (0)
 262
 263 #define __wait_event_timeout(wq, condition, timeout)                    \
 264         ___wait_event(wq, ___wait_cond_timeout(condition),              \
 265                       TASK_UNINTERRUPTIBLE, 0, timeout,                 \
 266                       __ret = schedule_timeout(__ret))
 267
 268 /**
 269  * wait_event_timeout - sleep until a condition gets true or a timeout elapses
 270  * @wq: the waitqueue to wait on
 271  * @condition: a C expression for the event to wait for
 272  * @timeout: timeout, in jiffies
 273  *
 274  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 275  * @condition evaluates to true. The @condition is checked each time
 276  * the waitqueue @wq is woken up.
 277  *
 278  * wake_up() has to be called after changing any variable that could
 279  * change the result of the wait condition.
 280  *
 281  * The function returns 0 if the @timeout elapsed, or the remaining
 282  * jiffies (at least 1) if the @condition evaluated to %true before
 283  * the @timeout elapsed.
 284  */
 285 #define wait_event_timeout(wq, condition, timeout)                      \
 286 ({                                                                      \
 287         long __ret = timeout;                                           \
 288         if (!___wait_cond_timeout(condition))                           \
 289                 __ret = __wait_event_timeout(wq, condition, timeout);   \
 290         __ret;                                                          \
 291 })
 292
 293 #define __wait_event_cmd(wq, condition, cmd1, cmd2)                     \
 294         (void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0, 0,  \
 295                             cmd1; schedule(); cmd2)
 296
 297 /**
 298  * wait_event_cmd - sleep until a condition gets true
 299  * @wq: the waitqueue to wait on
 300  * @condition: a C expression for the event to wait for
 301  * @cmd1: the command will be executed before sleep
 302  * @cmd2: the command will be executed after sleep
 303  *
 304  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 305  * @condition evaluates to true. The @condition is checked each time
 306  * the waitqueue @wq is woken up.
 307  *
 308  * wake_up() has to be called after changing any variable that could
 309  * change the result of the wait condition.
 310  */
 311 #define wait_event_cmd(wq, condition, cmd1, cmd2)                       \
 312 do {                                                                    \
 313         if (condition)                                                  \
 314                 break;                                                  \
 315         __wait_event_cmd(wq, condition, cmd1, cmd2);                    \
 316 } while (0)
 317
 318 #define __wait_event_interruptible(wq, condition)                       \
 319         ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 0, 0,          \
 320                       schedule())
 321
 322 /**
 323  * wait_event_interruptible - sleep until a condition gets true
 324  * @wq: the waitqueue to wait on
 325  * @condition: a C expression for the event to wait for
 326  *
 327  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 328  * @condition evaluates to true or a signal is received.
 329  * The @condition is checked each time the waitqueue @wq is woken up.
 330  *
 331  * wake_up() has to be called after changing any variable that could
 332  * change the result of the wait condition.
 333  *
 334  * The function will return -ERESTARTSYS if it was interrupted by a
 335  * signal and 0 if @condition evaluated to true.
 336  */
 337 #define wait_event_interruptible(wq, condition)                         \
 338 ({                                                                      \
 339         int __ret = 0;                                                  \
 340         if (!(condition))                                               \
 341                 __ret = __wait_event_interruptible(wq, condition);      \
 342         __ret;                                                          \
 343 })
 344
 345 #define __wait_event_interruptible_timeout(wq, condition, timeout)      \
 346         ___wait_event(wq, ___wait_cond_timeout(condition),              \
 347                       TASK_INTERRUPTIBLE, 0, timeout,                   \
 348                       __ret = schedule_timeout(__ret))
 349
 350 /**
 351  * wait_event_interruptible_timeout - sleep until a condition gets true or a timeout elapses
 352  * @wq: the waitqueue to wait on
 353  * @condition: a C expression for the event to wait for
 354  * @timeout: timeout, in jiffies
 355  *
 356  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 357  * @condition evaluates to true or a signal is received.
 358  * The @condition is checked each time the waitqueue @wq is woken up.
 359  *
 360  * wake_up() has to be called after changing any variable that could
 361  * change the result of the wait condition.
 362  *
 363  * Returns:
 364  * 0 if the @timeout elapsed, -%ERESTARTSYS if it was interrupted by
 365  * a signal, or the remaining jiffies (at least 1) if the @condition
 366  * evaluated to %true before the @timeout elapsed.
 367  */
 368 #define wait_event_interruptible_timeout(wq, condition, timeout)        \
 369 ({                                                                      \
 370         long __ret = timeout;                                           \
 371         if (!___wait_cond_timeout(condition))                           \
 372                 __ret = __wait_event_interruptible_timeout(wq,          \
 373                                                 condition, timeout);    \
 374         __ret;                                                          \
 375 })
 376
 377 #define __wait_event_hrtimeout(wq, condition, timeout, state)           \
 378 ({                                                                      \
 379         int __ret = 0;                                                  \
 380         struct hrtimer_sleeper __t;                                     \
 381                                                                         \
 382         hrtimer_init_on_stack(&__t.timer, CLOCK_MONOTONIC,              \
 383                               HRTIMER_MODE_REL);                        \
 384         hrtimer_init_sleeper(&__t, current);                            \
 385         if ((timeout).tv64 != KTIME_MAX)                                \
 386                 hrtimer_start_range_ns(&__t.timer, timeout,             \
 387                                        current->timer_slack_ns,         \
 388                                        HRTIMER_MODE_REL);               \
 389                                                                         \
 390         __ret = ___wait_event(wq, condition, state, 0, 0,               \
 391                 if (!__t.task) {                                        \
 392                         __ret = -ETIME;                                 \
 393                         break;                                          \
 394                 }                                                       \
 395                 schedule());                                            \
 396                                                                         \
 397         hrtimer_cancel(&__t.timer);                                     \
 398         destroy_hrtimer_on_stack(&__t.timer);                           \
 399         __ret;                                                          \
 400 })
 401
 402 /**
 403  * wait_event_hrtimeout - sleep until a condition gets true or a timeout elapses
 404  * @wq: the waitqueue to wait on
 405  * @condition: a C expression for the event to wait for
 406  * @timeout: timeout, as a ktime_t
 407  *
 408  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 409  * @condition evaluates to true or a signal is received.
 410  * The @condition is checked each time the waitqueue @wq is woken up.
 411  *
 412  * wake_up() has to be called after changing any variable that could
 413  * change the result of the wait condition.
 414  *
 415  * The function returns 0 if @condition became true, or -ETIME if the timeout
 416  * elapsed.
 417  */
 418 #define wait_event_hrtimeout(wq, condition, timeout)                    \
 419 ({                                                                      \
 420         int __ret = 0;                                                  \
 421         if (!(condition))                                               \
 422                 __ret = __wait_event_hrtimeout(wq, condition, timeout,  \
 423                                                TASK_UNINTERRUPTIBLE);   \
 424         __ret;                                                          \
 425 })
 426
 427 /**
 428  * wait_event_interruptible_hrtimeout - sleep until a condition gets true or a timeout elapses
 429  * @wq: the waitqueue to wait on
 430  * @condition: a C expression for the event to wait for
 431  * @timeout: timeout, as a ktime_t
 432  *
 433  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 434  * @condition evaluates to true or a signal is received.
 435  * The @condition is checked each time the waitqueue @wq is woken up.
 436  *
 437  * wake_up() has to be called after changing any variable that could
 438  * change the result of the wait condition.
 439  *
 440  * The function returns 0 if @condition became true, -ERESTARTSYS if it was
 441  * interrupted by a signal, or -ETIME if the timeout elapsed.
 442  */
 443 #define wait_event_interruptible_hrtimeout(wq, condition, timeout)      \
 444 ({                                                                      \
 445         long __ret = 0;                                                 \
 446         if (!(condition))                                               \
 447                 __ret = __wait_event_hrtimeout(wq, condition, timeout,  \
 448                                                TASK_INTERRUPTIBLE);     \
 449         __ret;                                                          \
 450 })
 451
 452 #define __wait_event_interruptible_exclusive(wq, condition)             \
 453         ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 1, 0,          \
 454                       schedule())
 455
 456 #define wait_event_interruptible_exclusive(wq, condition)               \
 457 ({                                                                      \
 458         int __ret = 0;                                                  \
 459         if (!(condition))                                               \
 460                 __ret = __wait_event_interruptible_exclusive(wq, condition);\
 461         __ret;                                                          \
 462 })
 463
 464
 465 #define __wait_event_interruptible_locked(wq, condition, exclusive, irq) \
 466 ({                                                                      \
 467         int __ret = 0;                                                  \
 468         DEFINE_WAIT(__wait);                                            \
 469         if (exclusive)                                                  \
 470                 __wait.flags |= WQ_FLAG_EXCLUSIVE;                      \
 471         do {                                                            \
 472                 if (likely(list_empty(&__wait.task_list)))              \
 473                         __add_wait_queue_tail(&(wq), &__wait);          \
 474                 set_current_state(TASK_INTERRUPTIBLE);                  \
 475                 if (signal_pending(current)) {                          \
 476                         __ret = -ERESTARTSYS;                           \
 477                         break;                                          \
 478                 }                                                       \
 479                 if (irq)                                                \
 480                         spin_unlock_irq(&(wq).lock);                    \
 481                 else                                                    \
 482                         spin_unlock(&(wq).lock);                        \
 483                 schedule();                                             \
 484                 if (irq)                                                \
 485                         spin_lock_irq(&(wq).lock);                      \
 486                 else                                                    \
 487                         spin_lock(&(wq).lock);                          \
 488         } while (!(condition));                                         \
 489         __remove_wait_queue(&(wq), &__wait);                            \
 490         __set_current_state(TASK_RUNNING);                              \
 491         __ret;                                                          \
 492 })
 493
 494
 495 /**
 496  * wait_event_interruptible_locked - sleep until a condition gets true
 497  * @wq: the waitqueue to wait on
 498  * @condition: a C expression for the event to wait for
 499  *
 500  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 501  * @condition evaluates to true or a signal is received.
 502  * The @condition is checked each time the waitqueue @wq is woken up.
 503  *
 504  * It must be called with wq.lock being held.  This spinlock is
 505  * unlocked while sleeping but @condition testing is done while lock
 506  * is held and when this macro exits the lock is held.
 507  *
 508  * The lock is locked/unlocked using spin_lock()/spin_unlock()
 509  * functions which must match the way they are locked/unlocked outside
 510  * of this macro.
 511  *
 512  * wake_up_locked() has to be called after changing any variable that could
 513  * change the result of the wait condition.
 514  *
 515  * The function will return -ERESTARTSYS if it was interrupted by a
 516  * signal and 0 if @condition evaluated to true.
 517  */
 518 #define wait_event_interruptible_locked(wq, condition)                  \
 519         ((condition)                                                    \
 520          ? 0 : __wait_event_interruptible_locked(wq, condition, 0, 0))
 521
 522 /**
 523  * wait_event_interruptible_locked_irq - sleep until a condition gets true
 524  * @wq: the waitqueue to wait on
 525  * @condition: a C expression for the event to wait for
 526  *
 527  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 528  * @condition evaluates to true or a signal is received.
 529  * The @condition is checked each time the waitqueue @wq is woken up.
 530  *
 531  * It must be called with wq.lock being held.  This spinlock is
 532  * unlocked while sleeping but @condition testing is done while lock
 533  * is held and when this macro exits the lock is held.
 534  *
 535  * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq()
 536  * functions which must match the way they are locked/unlocked outside
 537  * of this macro.
 538  *
 539  * wake_up_locked() has to be called after changing any variable that could
 540  * change the result of the wait condition.
 541  *
 542  * The function will return -ERESTARTSYS if it was interrupted by a
 543  * signal and 0 if @condition evaluated to true.
 544  */
 545 #define wait_event_interruptible_locked_irq(wq, condition)              \
 546         ((condition)                                                    \
 547          ? 0 : __wait_event_interruptible_locked(wq, condition, 0, 1))
 548
 549 /**
 550  * wait_event_interruptible_exclusive_locked - sleep exclusively until a condition gets true
 551  * @wq: the waitqueue to wait on
 552  * @condition: a C expression for the event to wait for
 553  *
 554  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 555  * @condition evaluates to true or a signal is received.
 556  * The @condition is checked each time the waitqueue @wq is woken up.
 557  *
 558  * It must be called with wq.lock being held.  This spinlock is
 559  * unlocked while sleeping but @condition testing is done while lock
 560  * is held and when this macro exits the lock is held.
 561  *
 562  * The lock is locked/unlocked using spin_lock()/spin_unlock()
 563  * functions which must match the way they are locked/unlocked outside
 564  * of this macro.
 565  *
 566  * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
 567  * set thus when other process waits process on the list if this
 568  * process is awaken further processes are not considered.
 569  *
 570  * wake_up_locked() has to be called after changing any variable that could
 571  * change the result of the wait condition.
 572  *
 573  * The function will return -ERESTARTSYS if it was interrupted by a
 574  * signal and 0 if @condition evaluated to true.
 575  */
 576 #define wait_event_interruptible_exclusive_locked(wq, condition)        \
 577         ((condition)                                                    \
 578          ? 0 : __wait_event_interruptible_locked(wq, condition, 1, 0))
 579
 580 /**
 581  * wait_event_interruptible_exclusive_locked_irq - sleep until a condition gets true
 582  * @wq: the waitqueue to wait on
 583  * @condition: a C expression for the event to wait for
 584  *
 585  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 586  * @condition evaluates to true or a signal is received.
 587  * The @condition is checked each time the waitqueue @wq is woken up.
 588  *
 589  * It must be called with wq.lock being held.  This spinlock is
 590  * unlocked while sleeping but @condition testing is done while lock
 591  * is held and when this macro exits the lock is held.
 592  *
 593  * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq()
 594  * functions which must match the way they are locked/unlocked outside
 595  * of this macro.
 596  *
 597  * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
 598  * set thus when other process waits process on the list if this
 599  * process is awaken further processes are not considered.
 600  *
 601  * wake_up_locked() has to be called after changing any variable that could
 602  * change the result of the wait condition.
 603  *
 604  * The function will return -ERESTARTSYS if it was interrupted by a
 605  * signal and 0 if @condition evaluated to true.
 606  */
 607 #define wait_event_interruptible_exclusive_locked_irq(wq, condition)    \
 608         ((condition)                                                    \
 609          ? 0 : __wait_event_interruptible_locked(wq, condition, 1, 1))
 610
 611
 612 #define __wait_event_killable(wq, condition)                            \
 613         ___wait_event(wq, condition, TASK_KILLABLE, 0, 0, schedule())
 614
 615 /**
 616  * wait_event_killable - sleep until a condition gets true
 617  * @wq: the waitqueue to wait on
 618  * @condition: a C expression for the event to wait for
 619  *
 620  * The process is put to sleep (TASK_KILLABLE) until the
 621  * @condition evaluates to true or a signal is received.
 622  * The @condition is checked each time the waitqueue @wq is woken up.
 623  *
 624  * wake_up() has to be called after changing any variable that could
 625  * change the result of the wait condition.
 626  *
 627  * The function will return -ERESTARTSYS if it was interrupted by a
 628  * signal and 0 if @condition evaluated to true.
 629  */
 630 #define wait_event_killable(wq, condition)                              \
 631 ({                                                                      \
 632         int __ret = 0;                                                  \
 633         if (!(condition))                                               \
 634                 __ret = __wait_event_killable(wq, condition);           \
 635         __ret;                                                          \
 636 })
 637
 638
 639 #define __wait_event_lock_irq(wq, condition, lock, cmd)                 \
 640         (void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0, 0,  \
 641                             spin_unlock_irq(&lock);                     \
 642                             cmd;                                        \
 643                             schedule();                                 \
 644                             spin_lock_irq(&lock))
 645
 646 /**
 647  * wait_event_lock_irq_cmd - sleep until a condition gets true. The
 648  *                           condition is checked under the lock. This
 649  *                           is expected to be called with the lock
 650  *                           taken.
 651  * @wq: the waitqueue to wait on
 652  * @condition: a C expression for the event to wait for
 653  * @lock: a locked spinlock_t, which will be released before cmd
 654  *        and schedule() and reacquired afterwards.
 655  * @cmd: a command which is invoked outside the critical section before
 656  *       sleep
 657  *
 658  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 659  * @condition evaluates to true. The @condition is checked each time
 660  * the waitqueue @wq is woken up.
 661  *
 662  * wake_up() has to be called after changing any variable that could
 663  * change the result of the wait condition.
 664  *
 665  * This is supposed to be called while holding the lock. The lock is
 666  * dropped before invoking the cmd and going to sleep and is reacquired
 667  * afterwards.
 668  */
 669 #define wait_event_lock_irq_cmd(wq, condition, lock, cmd)               \
 670 do {                                                                    \
 671         if (condition)                                                  \
 672                 break;                                                  \
 673         __wait_event_lock_irq(wq, condition, lock, cmd);                \
 674 } while (0)
 675
 676 /**
 677  * wait_event_lock_irq - sleep until a condition gets true. The
 678  *                       condition is checked under the lock. This
 679  *                       is expected to be called with the lock
 680  *                       taken.
 681  * @wq: the waitqueue to wait on
 682  * @condition: a C expression for the event to wait for
 683  * @lock: a locked spinlock_t, which will be released before schedule()
 684  *        and reacquired afterwards.
 685  *
 686  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 687  * @condition evaluates to true. The @condition is checked each time
 688  * the waitqueue @wq is woken up.
 689  *
 690  * wake_up() has to be called after changing any variable that could
 691  * change the result of the wait condition.
 692  *
 693  * This is supposed to be called while holding the lock. The lock is
 694  * dropped before going to sleep and is reacquired afterwards.
 695  */
 696 #define wait_event_lock_irq(wq, condition, lock)                        \
 697 do {                                                                    \
 698         if (condition)                                                  \
 699                 break;                                                  \
 700         __wait_event_lock_irq(wq, condition, lock, );                   \
 701 } while (0)
 702
 703
 704 #define __wait_event_interruptible_lock_irq(wq, condition, lock, cmd)   \
 705         ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 0, 0,          \
 706                       spin_unlock_irq(&lock);                           \
 707                       cmd;                                              \
 708                       schedule();                                       \
 709                       spin_lock_irq(&lock))
 710
 711 /**
 712  * wait_event_interruptible_lock_irq_cmd - sleep until a condition gets true.
 713  *              The condition is checked under the lock. This is expected to
 714  *              be called with the lock taken.
 715  * @wq: the waitqueue to wait on
 716  * @condition: a C expression for the event to wait for
 717  * @lock: a locked spinlock_t, which will be released before cmd and
 718  *        schedule() and reacquired afterwards.
 719  * @cmd: a command which is invoked outside the critical section before
 720  *       sleep
 721  *
 722  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 723  * @condition evaluates to true or a signal is received. The @condition is
 724  * checked each time the waitqueue @wq is woken up.
 725  *
 726  * wake_up() has to be called after changing any variable that could
 727  * change the result of the wait condition.
 728  *
 729  * This is supposed to be called while holding the lock. The lock is
 730  * dropped before invoking the cmd and going to sleep and is reacquired
 731  * afterwards.
 732  *
 733  * The macro will return -ERESTARTSYS if it was interrupted by a signal
 734  * and 0 if @condition evaluated to true.
 735  */
 736 #define wait_event_interruptible_lock_irq_cmd(wq, condition, lock, cmd) \
 737 ({                                                                      \
 738         int __ret = 0;                                                  \
 739         if (!(condition))                                               \
 740                 __ret = __wait_event_interruptible_lock_irq(wq,         \
 741                                                 condition, lock, cmd);  \
 742         __ret;                                                          \
 743 })
 744
 745 /**
 746  * wait_event_interruptible_lock_irq - sleep until a condition gets true.
 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  *
 754  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 755  * @condition evaluates to true or signal is received. The @condition is
 756  * checked each time the waitqueue @wq is woken up.
 757  *
 758  * wake_up() has to be called after changing any variable that could
 759  * change the result of the wait condition.
 760  *
 761  * This is supposed to be called while holding the lock. The lock is
 762  * dropped before going to sleep and is reacquired afterwards.
 763  *
 764  * The macro will return -ERESTARTSYS if it was interrupted by a signal
 765  * and 0 if @condition evaluated to true.
 766  */
 767 #define wait_event_interruptible_lock_irq(wq, condition, lock)          \
 768 ({                                                                      \
 769         int __ret = 0;                                                  \
 770         if (!(condition))                                               \
 771                 __ret = __wait_event_interruptible_lock_irq(wq,         \
 772                                                 condition, lock,);      \
 773         __ret;                                                          \
 774 })
 775
 776 #define __wait_event_interruptible_lock_irq_timeout(wq, condition,      \
 777                                                     lock, timeout)      \
 778         ___wait_event(wq, ___wait_cond_timeout(condition),              \
 779                       TASK_INTERRUPTIBLE, 0, timeout,                   \
 780                       spin_unlock_irq(&lock);                           \
 781                       __ret = schedule_timeout(__ret);                  \
 782                       spin_lock_irq(&lock));
 783
 784 /**
 785  * wait_event_interruptible_lock_irq_timeout - sleep until a condition gets
 786  *              true or a timeout elapses. The condition is checked under
 787  *              the lock. This is expected to be called with the lock taken.
 788  * @wq: the waitqueue to wait on
 789  * @condition: a C expression for the event to wait for
 790  * @lock: a locked spinlock_t, which will be released before schedule()
 791  *        and reacquired afterwards.
 792  * @timeout: timeout, in jiffies
 793  *
 794  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 795  * @condition evaluates to true or signal is received. The @condition is
 796  * checked each time the waitqueue @wq is woken up.
 797  *
 798  * wake_up() has to be called after changing any variable that could
 799  * change the result of the wait condition.
 800  *
 801  * This is supposed to be called while holding the lock. The lock is
 802  * dropped before going to sleep and is reacquired afterwards.
 803  *
 804  * The function returns 0 if the @timeout elapsed, -ERESTARTSYS if it
 805  * was interrupted by a signal, and the remaining jiffies otherwise
 806  * if the condition evaluated to true before the timeout elapsed.
 807  */
 808 #define wait_event_interruptible_lock_irq_timeout(wq, condition, lock,  \
 809                                                   timeout)              \
 810 ({                                                                      \
 811         long __ret = timeout;                                           \
 812         if (!___wait_cond_timeout(condition))                           \
 813                 __ret = __wait_event_interruptible_lock_irq_timeout(    \
 814                                         wq, condition, lock, timeout);  \
 815         __ret;                                                          \
 816 })
 817
 818 /*
 819  * Waitqueues which are removed from the waitqueue_head at wakeup time
 820  */
 821 void prepare_to_wait(wait_queue_head_t *q, wait_queue_t *wait, int state);
 822 void prepare_to_wait_exclusive(wait_queue_head_t *q, wait_queue_t *wait, int state);
 823 long prepare_to_wait_event(wait_queue_head_t *q, wait_queue_t *wait, int state);
 824 void finish_wait(wait_queue_head_t *q, wait_queue_t *wait);
 825 void abort_exclusive_wait(wait_queue_head_t *q, wait_queue_t *wait, unsigned int mode, void *key);
 826 int autoremove_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 827 int wake_bit_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 828
 829 #define DEFINE_WAIT_FUNC(name, function)                                \
 830         wait_queue_t name = {                                           \
 831                 .private        = current,                              \
 832                 .func           = function,                             \
 833                 .task_list      = LIST_HEAD_INIT((name).task_list),     \
 834         }
 835
 836 #define DEFINE_WAIT(name) DEFINE_WAIT_FUNC(name, autoremove_wake_function)
 837
 838 #define DEFINE_WAIT_BIT(name, word, bit)                                \
 839         struct wait_bit_queue name = {                                  \
 840                 .key = __WAIT_BIT_KEY_INITIALIZER(word, bit),           \
 841                 .wait   = {                                             \
 842                         .private        = current,                      \
 843                         .func           = wake_bit_function,            \
 844                         .task_list      =                               \
 845                                 LIST_HEAD_INIT((name).wait.task_list),  \
 846                 },                                                      \
 847         }
 848
 849 #define init_wait(wait)                                                 \
 850         do {                                                            \
 851                 (wait)->private = current;                              \
 852                 (wait)->func = autoremove_wake_function;                \
 853                 INIT_LIST_HEAD(&(wait)->task_list);                     \
 854                 (wait)->flags = 0;                                      \
 855         } while (0)
 856
 857 /**
 858  * wait_on_bit - wait for a bit to be cleared
 859  * @word: the word being waited on, a kernel virtual address
 860  * @bit: the bit of the word being waited on
 861  * @action: the function used to sleep, which may take special actions
 862  * @mode: the task state to sleep in
 863  *
 864  * There is a standard hashed waitqueue table for generic use. This
 865  * is the part of the hashtable's accessor API that waits on a bit.
 866  * For instance, if one were to have waiters on a bitflag, one would
 867  * call wait_on_bit() in threads waiting for the bit to clear.
 868  * One uses wait_on_bit() where one is waiting for the bit to clear,
 869  * but has no intention of setting it.
 870  */
 871 static inline int
 872 wait_on_bit(void *word, int bit, int (*action)(void *), unsigned mode)
 873 {
 874         if (!test_bit(bit, word))
 875                 return 0;
 876         return out_of_line_wait_on_bit(word, bit, action, mode);
 877 }
 878
 879 /**
 880  * wait_on_bit_lock - wait for a bit to be cleared, when wanting to set it
 881  * @word: the word being waited on, a kernel virtual address
 882  * @bit: the bit of the word being waited on
 883  * @action: the function used to sleep, which may take special actions
 884  * @mode: the task state to sleep in
 885  *
 886  * There is a standard hashed waitqueue table for generic use. This
 887  * is the part of the hashtable's accessor API that waits on a bit
 888  * when one intends to set it, for instance, trying to lock bitflags.
 889  * For instance, if one were to have waiters trying to set bitflag
 890  * and waiting for it to clear before setting it, one would call
 891  * wait_on_bit() in threads waiting to be able to set the bit.
 892  * One uses wait_on_bit_lock() where one is waiting for the bit to
 893  * clear with the intention of setting it, and when done, clearing it.
 894  */
 895 static inline int
 896 wait_on_bit_lock(void *word, int bit, int (*action)(void *), unsigned mode)
 897 {
 898         if (!test_and_set_bit(bit, word))
 899                 return 0;
 900         return out_of_line_wait_on_bit_lock(word, bit, action, mode);
 901 }
 902
 903 /**
 904  * wait_on_atomic_t - Wait for an atomic_t to become 0
 905  * @val: The atomic value being waited on, a kernel virtual address
 906  * @action: the function used to sleep, which may take special actions
 907  * @mode: the task state to sleep in
 908  *
 909  * Wait for an atomic_t to become 0.  We abuse the bit-wait waitqueue table for
 910  * the purpose of getting a waitqueue, but we set the key to a bit number
 911  * outside of the target 'word'.
 912  */
 913 static inline
 914 int wait_on_atomic_t(atomic_t *val, int (*action)(atomic_t *), unsigned mode)
 915 {
 916         if (atomic_read(val) == 0)
 917                 return 0;
 918         return out_of_line_wait_on_atomic_t(val, action, mode);
 919 }
 920
 921 #endif /* _LINUX_WAIT_H */