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 #define ___wait_event(wq, condition, state, exclusive, ret, cmd)        \
 195 ({                                                                      \
 196         __label__ __out;                                                \
 197         wait_queue_t __wait;                                            \
 198         long __ret = ret;                                               \
 199                                                                         \
 200         INIT_LIST_HEAD(&__wait.task_list);                              \
 201         if (exclusive)                                                  \
 202                 __wait.flags = WQ_FLAG_EXCLUSIVE;                       \
 203         else                                                            \
 204                 __wait.flags = 0;                                       \
 205                                                                         \
 206         for (;;) {                                                      \
 207                 long __int = prepare_to_wait_event(&wq, &__wait, state);\
 208                                                                         \
 209                 if (condition)                                          \
 210                         break;                                          \
 211                                                                         \
 212                 if (___wait_is_interruptible(state) && __int) {         \
 213                         __ret = __int;                                  \
 214                         if (exclusive) {                                \
 215                                 abort_exclusive_wait(&wq, &__wait,      \
 216                                                      state, NULL);      \
 217                                 goto __out;                             \
 218                         }                                               \
 219                         break;                                          \
 220                 }                                                       \
 221                                                                         \
 222                 cmd;                                                    \
 223         }                                                               \
 224         finish_wait(&wq, &__wait);                                      \
 225 __out:  __ret;                                                          \
 226 })
 227
 228 #define __wait_event(wq, condition)                                     \
 229         (void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0, 0,  \
 230                             schedule())
 231
 232 /**
 233  * wait_event - sleep until a condition gets true
 234  * @wq: the waitqueue to wait on
 235  * @condition: a C expression for the event to wait for
 236  *
 237  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 238  * @condition evaluates to true. The @condition is checked each time
 239  * the waitqueue @wq is woken up.
 240  *
 241  * wake_up() has to be called after changing any variable that could
 242  * change the result of the wait condition.
 243  */
 244 #define wait_event(wq, condition)                                       \
 245 do {                                                                    \
 246         if (condition)                                                  \
 247                 break;                                                  \
 248         __wait_event(wq, condition);                                    \
 249 } while (0)
 250
 251 #define __wait_event_timeout(wq, condition, timeout)                    \
 252         ___wait_event(wq, ___wait_cond_timeout(condition),              \
 253                       TASK_UNINTERRUPTIBLE, 0, timeout,                 \
 254                       __ret = schedule_timeout(__ret))
 255
 256 /**
 257  * wait_event_timeout - sleep until a condition gets true or a timeout elapses
 258  * @wq: the waitqueue to wait on
 259  * @condition: a C expression for the event to wait for
 260  * @timeout: timeout, in jiffies
 261  *
 262  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 263  * @condition evaluates to true. The @condition is checked each time
 264  * the waitqueue @wq is woken up.
 265  *
 266  * wake_up() has to be called after changing any variable that could
 267  * change the result of the wait condition.
 268  *
 269  * The function returns 0 if the @timeout elapsed, or the remaining
 270  * jiffies (at least 1) if the @condition evaluated to %true before
 271  * the @timeout elapsed.
 272  */
 273 #define wait_event_timeout(wq, condition, timeout)                      \
 274 ({                                                                      \
 275         long __ret = timeout;                                           \
 276         if (!___wait_cond_timeout(condition))                           \
 277                 __ret = __wait_event_timeout(wq, condition, timeout);   \
 278         __ret;                                                          \
 279 })
 280
 281 #define __wait_event_cmd(wq, condition, cmd1, cmd2)                     \
 282         (void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0, 0,  \
 283                             cmd1; schedule(); cmd2)
 284
 285 /**
 286  * wait_event_cmd - sleep until a condition gets true
 287  * @wq: the waitqueue to wait on
 288  * @condition: a C expression for the event to wait for
 289  * @cmd1: the command will be executed before sleep
 290  * @cmd2: the command will be executed after sleep
 291  *
 292  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 293  * @condition evaluates to true. The @condition is checked each time
 294  * the waitqueue @wq is woken up.
 295  *
 296  * wake_up() has to be called after changing any variable that could
 297  * change the result of the wait condition.
 298  */
 299 #define wait_event_cmd(wq, condition, cmd1, cmd2)                       \
 300 do {                                                                    \
 301         if (condition)                                                  \
 302                 break;                                                  \
 303         __wait_event_cmd(wq, condition, cmd1, cmd2);                    \
 304 } while (0)
 305
 306 #define __wait_event_interruptible(wq, condition)                       \
 307         ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 0, 0,          \
 308                       schedule())
 309
 310 /**
 311  * wait_event_interruptible - sleep until a condition gets true
 312  * @wq: the waitqueue to wait on
 313  * @condition: a C expression for the event to wait for
 314  *
 315  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 316  * @condition evaluates to true or a signal is received.
 317  * The @condition is checked each time the waitqueue @wq is woken up.
 318  *
 319  * wake_up() has to be called after changing any variable that could
 320  * change the result of the wait condition.
 321  *
 322  * The function will return -ERESTARTSYS if it was interrupted by a
 323  * signal and 0 if @condition evaluated to true.
 324  */
 325 #define wait_event_interruptible(wq, condition)                         \
 326 ({                                                                      \
 327         int __ret = 0;                                                  \
 328         if (!(condition))                                               \
 329                 __ret = __wait_event_interruptible(wq, condition);      \
 330         __ret;                                                          \
 331 })
 332
 333 #define __wait_event_interruptible_timeout(wq, condition, timeout)      \
 334         ___wait_event(wq, ___wait_cond_timeout(condition),              \
 335                       TASK_INTERRUPTIBLE, 0, timeout,                   \
 336                       __ret = schedule_timeout(__ret))
 337
 338 /**
 339  * wait_event_interruptible_timeout - sleep until a condition gets true or a timeout elapses
 340  * @wq: the waitqueue to wait on
 341  * @condition: a C expression for the event to wait for
 342  * @timeout: timeout, in jiffies
 343  *
 344  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 345  * @condition evaluates to true or a signal is received.
 346  * The @condition is checked each time the waitqueue @wq is woken up.
 347  *
 348  * wake_up() has to be called after changing any variable that could
 349  * change the result of the wait condition.
 350  *
 351  * Returns:
 352  * 0 if the @timeout elapsed, -%ERESTARTSYS if it was interrupted by
 353  * a signal, or the remaining jiffies (at least 1) if the @condition
 354  * evaluated to %true before the @timeout elapsed.
 355  */
 356 #define wait_event_interruptible_timeout(wq, condition, timeout)        \
 357 ({                                                                      \
 358         long __ret = timeout;                                           \
 359         if (!___wait_cond_timeout(condition))                           \
 360                 __ret = __wait_event_interruptible_timeout(wq,          \
 361                                                 condition, timeout);    \
 362         __ret;                                                          \
 363 })
 364
 365 #define __wait_event_hrtimeout(wq, condition, timeout, state)           \
 366 ({                                                                      \
 367         int __ret = 0;                                                  \
 368         struct hrtimer_sleeper __t;                                     \
 369                                                                         \
 370         hrtimer_init_on_stack(&__t.timer, CLOCK_MONOTONIC,              \
 371                               HRTIMER_MODE_REL);                        \
 372         hrtimer_init_sleeper(&__t, current);                            \
 373         if ((timeout).tv64 != KTIME_MAX)                                \
 374                 hrtimer_start_range_ns(&__t.timer, timeout,             \
 375                                        current->timer_slack_ns,         \
 376                                        HRTIMER_MODE_REL);               \
 377                                                                         \
 378         __ret = ___wait_event(wq, condition, state, 0, 0,               \
 379                 if (!__t.task) {                                        \
 380                         __ret = -ETIME;                                 \
 381                         break;                                          \
 382                 }                                                       \
 383                 schedule());                                            \
 384                                                                         \
 385         hrtimer_cancel(&__t.timer);                                     \
 386         destroy_hrtimer_on_stack(&__t.timer);                           \
 387         __ret;                                                          \
 388 })
 389
 390 /**
 391  * wait_event_hrtimeout - sleep until a condition gets true or a timeout elapses
 392  * @wq: the waitqueue to wait on
 393  * @condition: a C expression for the event to wait for
 394  * @timeout: timeout, as a ktime_t
 395  *
 396  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 397  * @condition evaluates to true or a signal is received.
 398  * The @condition is checked each time the waitqueue @wq is woken up.
 399  *
 400  * wake_up() has to be called after changing any variable that could
 401  * change the result of the wait condition.
 402  *
 403  * The function returns 0 if @condition became true, or -ETIME if the timeout
 404  * elapsed.
 405  */
 406 #define wait_event_hrtimeout(wq, condition, timeout)                    \
 407 ({                                                                      \
 408         int __ret = 0;                                                  \
 409         if (!(condition))                                               \
 410                 __ret = __wait_event_hrtimeout(wq, condition, timeout,  \
 411                                                TASK_UNINTERRUPTIBLE);   \
 412         __ret;                                                          \
 413 })
 414
 415 /**
 416  * wait_event_interruptible_hrtimeout - sleep until a condition gets true or a timeout elapses
 417  * @wq: the waitqueue to wait on
 418  * @condition: a C expression for the event to wait for
 419  * @timeout: timeout, as a ktime_t
 420  *
 421  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 422  * @condition evaluates to true or a signal is received.
 423  * The @condition is checked each time the waitqueue @wq is woken up.
 424  *
 425  * wake_up() has to be called after changing any variable that could
 426  * change the result of the wait condition.
 427  *
 428  * The function returns 0 if @condition became true, -ERESTARTSYS if it was
 429  * interrupted by a signal, or -ETIME if the timeout elapsed.
 430  */
 431 #define wait_event_interruptible_hrtimeout(wq, condition, timeout)      \
 432 ({                                                                      \
 433         long __ret = 0;                                                 \
 434         if (!(condition))                                               \
 435                 __ret = __wait_event_hrtimeout(wq, condition, timeout,  \
 436                                                TASK_INTERRUPTIBLE);     \
 437         __ret;                                                          \
 438 })
 439
 440 #define __wait_event_interruptible_exclusive(wq, condition)             \
 441         ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 1, 0,          \
 442                       schedule())
 443
 444 #define wait_event_interruptible_exclusive(wq, condition)               \
 445 ({                                                                      \
 446         int __ret = 0;                                                  \
 447         if (!(condition))                                               \
 448                 __ret = __wait_event_interruptible_exclusive(wq, condition);\
 449         __ret;                                                          \
 450 })
 451
 452
 453 #define __wait_event_interruptible_locked(wq, condition, exclusive, irq) \
 454 ({                                                                      \
 455         int __ret = 0;                                                  \
 456         DEFINE_WAIT(__wait);                                            \
 457         if (exclusive)                                                  \
 458                 __wait.flags |= WQ_FLAG_EXCLUSIVE;                      \
 459         do {                                                            \
 460                 if (likely(list_empty(&__wait.task_list)))              \
 461                         __add_wait_queue_tail(&(wq), &__wait);          \
 462                 set_current_state(TASK_INTERRUPTIBLE);                  \
 463                 if (signal_pending(current)) {                          \
 464                         __ret = -ERESTARTSYS;                           \
 465                         break;                                          \
 466                 }                                                       \
 467                 if (irq)                                                \
 468                         spin_unlock_irq(&(wq).lock);                    \
 469                 else                                                    \
 470                         spin_unlock(&(wq).lock);                        \
 471                 schedule();                                             \
 472                 if (irq)                                                \
 473                         spin_lock_irq(&(wq).lock);                      \
 474                 else                                                    \
 475                         spin_lock(&(wq).lock);                          \
 476         } while (!(condition));                                         \
 477         __remove_wait_queue(&(wq), &__wait);                            \
 478         __set_current_state(TASK_RUNNING);                              \
 479         __ret;                                                          \
 480 })
 481
 482
 483 /**
 484  * wait_event_interruptible_locked - sleep until a condition gets true
 485  * @wq: the waitqueue to wait on
 486  * @condition: a C expression for the event to wait for
 487  *
 488  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 489  * @condition evaluates to true or a signal is received.
 490  * The @condition is checked each time the waitqueue @wq is woken up.
 491  *
 492  * It must be called with wq.lock being held.  This spinlock is
 493  * unlocked while sleeping but @condition testing is done while lock
 494  * is held and when this macro exits the lock is held.
 495  *
 496  * The lock is locked/unlocked using spin_lock()/spin_unlock()
 497  * functions which must match the way they are locked/unlocked outside
 498  * of this macro.
 499  *
 500  * wake_up_locked() has to be called after changing any variable that could
 501  * change the result of the wait condition.
 502  *
 503  * The function will return -ERESTARTSYS if it was interrupted by a
 504  * signal and 0 if @condition evaluated to true.
 505  */
 506 #define wait_event_interruptible_locked(wq, condition)                  \
 507         ((condition)                                                    \
 508          ? 0 : __wait_event_interruptible_locked(wq, condition, 0, 0))
 509
 510 /**
 511  * wait_event_interruptible_locked_irq - sleep until a condition gets true
 512  * @wq: the waitqueue to wait on
 513  * @condition: a C expression for the event to wait for
 514  *
 515  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 516  * @condition evaluates to true or a signal is received.
 517  * The @condition is checked each time the waitqueue @wq is woken up.
 518  *
 519  * It must be called with wq.lock being held.  This spinlock is
 520  * unlocked while sleeping but @condition testing is done while lock
 521  * is held and when this macro exits the lock is held.
 522  *
 523  * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq()
 524  * functions which must match the way they are locked/unlocked outside
 525  * of this macro.
 526  *
 527  * wake_up_locked() has to be called after changing any variable that could
 528  * change the result of the wait condition.
 529  *
 530  * The function will return -ERESTARTSYS if it was interrupted by a
 531  * signal and 0 if @condition evaluated to true.
 532  */
 533 #define wait_event_interruptible_locked_irq(wq, condition)              \
 534         ((condition)                                                    \
 535          ? 0 : __wait_event_interruptible_locked(wq, condition, 0, 1))
 536
 537 /**
 538  * wait_event_interruptible_exclusive_locked - sleep exclusively until a condition gets true
 539  * @wq: the waitqueue to wait on
 540  * @condition: a C expression for the event to wait for
 541  *
 542  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 543  * @condition evaluates to true or a signal is received.
 544  * The @condition is checked each time the waitqueue @wq is woken up.
 545  *
 546  * It must be called with wq.lock being held.  This spinlock is
 547  * unlocked while sleeping but @condition testing is done while lock
 548  * is held and when this macro exits the lock is held.
 549  *
 550  * The lock is locked/unlocked using spin_lock()/spin_unlock()
 551  * functions which must match the way they are locked/unlocked outside
 552  * of this macro.
 553  *
 554  * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
 555  * set thus when other process waits process on the list if this
 556  * process is awaken further processes are not considered.
 557  *
 558  * wake_up_locked() has to be called after changing any variable that could
 559  * change the result of the wait condition.
 560  *
 561  * The function will return -ERESTARTSYS if it was interrupted by a
 562  * signal and 0 if @condition evaluated to true.
 563  */
 564 #define wait_event_interruptible_exclusive_locked(wq, condition)        \
 565         ((condition)                                                    \
 566          ? 0 : __wait_event_interruptible_locked(wq, condition, 1, 0))
 567
 568 /**
 569  * wait_event_interruptible_exclusive_locked_irq - sleep until a condition gets true
 570  * @wq: the waitqueue to wait on
 571  * @condition: a C expression for the event to wait for
 572  *
 573  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 574  * @condition evaluates to true or a signal is received.
 575  * The @condition is checked each time the waitqueue @wq is woken up.
 576  *
 577  * It must be called with wq.lock being held.  This spinlock is
 578  * unlocked while sleeping but @condition testing is done while lock
 579  * is held and when this macro exits the lock is held.
 580  *
 581  * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq()
 582  * functions which must match the way they are locked/unlocked outside
 583  * of this macro.
 584  *
 585  * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
 586  * set thus when other process waits process on the list if this
 587  * process is awaken further processes are not considered.
 588  *
 589  * wake_up_locked() has to be called after changing any variable that could
 590  * change the result of the wait condition.
 591  *
 592  * The function will return -ERESTARTSYS if it was interrupted by a
 593  * signal and 0 if @condition evaluated to true.
 594  */
 595 #define wait_event_interruptible_exclusive_locked_irq(wq, condition)    \
 596         ((condition)                                                    \
 597          ? 0 : __wait_event_interruptible_locked(wq, condition, 1, 1))
 598
 599
 600 #define __wait_event_killable(wq, condition)                            \
 601         ___wait_event(wq, condition, TASK_KILLABLE, 0, 0, schedule())
 602
 603 /**
 604  * wait_event_killable - sleep until a condition gets true
 605  * @wq: the waitqueue to wait on
 606  * @condition: a C expression for the event to wait for
 607  *
 608  * The process is put to sleep (TASK_KILLABLE) until the
 609  * @condition evaluates to true or a signal is received.
 610  * The @condition is checked each time the waitqueue @wq is woken up.
 611  *
 612  * wake_up() has to be called after changing any variable that could
 613  * change the result of the wait condition.
 614  *
 615  * The function will return -ERESTARTSYS if it was interrupted by a
 616  * signal and 0 if @condition evaluated to true.
 617  */
 618 #define wait_event_killable(wq, condition)                              \
 619 ({                                                                      \
 620         int __ret = 0;                                                  \
 621         if (!(condition))                                               \
 622                 __ret = __wait_event_killable(wq, condition);           \
 623         __ret;                                                          \
 624 })
 625
 626
 627 #define __wait_event_lock_irq(wq, condition, lock, cmd)                 \
 628         (void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0, 0,  \
 629                             spin_unlock_irq(&lock);                     \
 630                             cmd;                                        \
 631                             schedule();                                 \
 632                             spin_lock_irq(&lock))
 633
 634 /**
 635  * wait_event_lock_irq_cmd - sleep until a condition gets true. The
 636  *                           condition is checked under the lock. This
 637  *                           is expected to be called with the lock
 638  *                           taken.
 639  * @wq: the waitqueue to wait on
 640  * @condition: a C expression for the event to wait for
 641  * @lock: a locked spinlock_t, which will be released before cmd
 642  *        and schedule() and reacquired afterwards.
 643  * @cmd: a command which is invoked outside the critical section before
 644  *       sleep
 645  *
 646  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 647  * @condition evaluates to true. The @condition is checked each time
 648  * the waitqueue @wq is woken up.
 649  *
 650  * wake_up() has to be called after changing any variable that could
 651  * change the result of the wait condition.
 652  *
 653  * This is supposed to be called while holding the lock. The lock is
 654  * dropped before invoking the cmd and going to sleep and is reacquired
 655  * afterwards.
 656  */
 657 #define wait_event_lock_irq_cmd(wq, condition, lock, cmd)               \
 658 do {                                                                    \
 659         if (condition)                                                  \
 660                 break;                                                  \
 661         __wait_event_lock_irq(wq, condition, lock, cmd);                \
 662 } while (0)
 663
 664 /**
 665  * wait_event_lock_irq - sleep until a condition gets true. The
 666  *                       condition is checked under the lock. This
 667  *                       is expected to be called with the lock
 668  *                       taken.
 669  * @wq: the waitqueue to wait on
 670  * @condition: a C expression for the event to wait for
 671  * @lock: a locked spinlock_t, which will be released before schedule()
 672  *        and reacquired afterwards.
 673  *
 674  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 675  * @condition evaluates to true. The @condition is checked each time
 676  * the waitqueue @wq is woken up.
 677  *
 678  * wake_up() has to be called after changing any variable that could
 679  * change the result of the wait condition.
 680  *
 681  * This is supposed to be called while holding the lock. The lock is
 682  * dropped before going to sleep and is reacquired afterwards.
 683  */
 684 #define wait_event_lock_irq(wq, condition, lock)                        \
 685 do {                                                                    \
 686         if (condition)                                                  \
 687                 break;                                                  \
 688         __wait_event_lock_irq(wq, condition, lock, );                   \
 689 } while (0)
 690
 691
 692 #define __wait_event_interruptible_lock_irq(wq, condition, lock, cmd)   \
 693         ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 0, 0,          \
 694                       spin_unlock_irq(&lock);                           \
 695                       cmd;                                              \
 696                       schedule();                                       \
 697                       spin_lock_irq(&lock))
 698
 699 /**
 700  * wait_event_interruptible_lock_irq_cmd - sleep until a condition gets true.
 701  *              The condition is checked under the lock. This is expected to
 702  *              be called with the lock taken.
 703  * @wq: the waitqueue to wait on
 704  * @condition: a C expression for the event to wait for
 705  * @lock: a locked spinlock_t, which will be released before cmd and
 706  *        schedule() and reacquired afterwards.
 707  * @cmd: a command which is invoked outside the critical section before
 708  *       sleep
 709  *
 710  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 711  * @condition evaluates to true or a signal is received. The @condition is
 712  * checked each time the waitqueue @wq is woken up.
 713  *
 714  * wake_up() has to be called after changing any variable that could
 715  * change the result of the wait condition.
 716  *
 717  * This is supposed to be called while holding the lock. The lock is
 718  * dropped before invoking the cmd and going to sleep and is reacquired
 719  * afterwards.
 720  *
 721  * The macro will return -ERESTARTSYS if it was interrupted by a signal
 722  * and 0 if @condition evaluated to true.
 723  */
 724 #define wait_event_interruptible_lock_irq_cmd(wq, condition, lock, cmd) \
 725 ({                                                                      \
 726         int __ret = 0;                                                  \
 727         if (!(condition))                                               \
 728                 __ret = __wait_event_interruptible_lock_irq(wq,         \
 729                                                 condition, lock, cmd);  \
 730         __ret;                                                          \
 731 })
 732
 733 /**
 734  * wait_event_interruptible_lock_irq - sleep until a condition gets true.
 735  *              The condition is checked under the lock. This is expected
 736  *              to be called with the lock taken.
 737  * @wq: the waitqueue to wait on
 738  * @condition: a C expression for the event to wait for
 739  * @lock: a locked spinlock_t, which will be released before schedule()
 740  *        and reacquired afterwards.
 741  *
 742  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 743  * @condition evaluates to true or signal is received. The @condition is
 744  * checked each time the waitqueue @wq is woken up.
 745  *
 746  * wake_up() has to be called after changing any variable that could
 747  * change the result of the wait condition.
 748  *
 749  * This is supposed to be called while holding the lock. The lock is
 750  * dropped before going to sleep and is reacquired afterwards.
 751  *
 752  * The macro will return -ERESTARTSYS if it was interrupted by a signal
 753  * and 0 if @condition evaluated to true.
 754  */
 755 #define wait_event_interruptible_lock_irq(wq, condition, lock)          \
 756 ({                                                                      \
 757         int __ret = 0;                                                  \
 758         if (!(condition))                                               \
 759                 __ret = __wait_event_interruptible_lock_irq(wq,         \
 760                                                 condition, lock,);      \
 761         __ret;                                                          \
 762 })
 763
 764 #define __wait_event_interruptible_lock_irq_timeout(wq, condition,      \
 765                                                     lock, timeout)      \
 766         ___wait_event(wq, ___wait_cond_timeout(condition),              \
 767                       TASK_INTERRUPTIBLE, 0, timeout,                   \
 768                       spin_unlock_irq(&lock);                           \
 769                       __ret = schedule_timeout(__ret);                  \
 770                       spin_lock_irq(&lock));
 771
 772 /**
 773  * wait_event_interruptible_lock_irq_timeout - sleep until a condition gets
 774  *              true or a timeout elapses. The condition is checked under
 775  *              the lock. This is expected to be called with the lock taken.
 776  * @wq: the waitqueue to wait on
 777  * @condition: a C expression for the event to wait for
 778  * @lock: a locked spinlock_t, which will be released before schedule()
 779  *        and reacquired afterwards.
 780  * @timeout: timeout, in jiffies
 781  *
 782  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 783  * @condition evaluates to true or signal is received. The @condition is
 784  * checked each time the waitqueue @wq is woken up.
 785  *
 786  * wake_up() has to be called after changing any variable that could
 787  * change the result of the wait condition.
 788  *
 789  * This is supposed to be called while holding the lock. The lock is
 790  * dropped before going to sleep and is reacquired afterwards.
 791  *
 792  * The function returns 0 if the @timeout elapsed, -ERESTARTSYS if it
 793  * was interrupted by a signal, and the remaining jiffies otherwise
 794  * if the condition evaluated to true before the timeout elapsed.
 795  */
 796 #define wait_event_interruptible_lock_irq_timeout(wq, condition, lock,  \
 797                                                   timeout)              \
 798 ({                                                                      \
 799         long __ret = timeout;                                           \
 800         if (!___wait_cond_timeout(condition))                           \
 801                 __ret = __wait_event_interruptible_lock_irq_timeout(    \
 802                                         wq, condition, lock, timeout);  \
 803         __ret;                                                          \
 804 })
 805
 806
 807 /*
 808  * These are the old interfaces to sleep waiting for an event.
 809  * They are racy.  DO NOT use them, use the wait_event* interfaces above.
 810  * We plan to remove these interfaces.
 811  */
 812 extern void sleep_on(wait_queue_head_t *q);
 813 extern long sleep_on_timeout(wait_queue_head_t *q, signed long timeout);
 814 extern void interruptible_sleep_on(wait_queue_head_t *q);
 815 extern long interruptible_sleep_on_timeout(wait_queue_head_t *q, signed long timeout);
 816
 817 /*
 818  * Waitqueues which are removed from the waitqueue_head at wakeup time
 819  */
 820 void prepare_to_wait(wait_queue_head_t *q, wait_queue_t *wait, int state);
 821 void prepare_to_wait_exclusive(wait_queue_head_t *q, wait_queue_t *wait, int state);
 822 long prepare_to_wait_event(wait_queue_head_t *q, wait_queue_t *wait, int state);
 823 void finish_wait(wait_queue_head_t *q, wait_queue_t *wait);
 824 void abort_exclusive_wait(wait_queue_head_t *q, wait_queue_t *wait, unsigned int mode, void *key);
 825 int autoremove_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 826 int wake_bit_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 827
 828 #define DEFINE_WAIT_FUNC(name, function)                                \
 829         wait_queue_t name = {                                           \
 830                 .private        = current,                              \
 831                 .func           = function,                             \
 832                 .task_list      = LIST_HEAD_INIT((name).task_list),     \
 833         }
 834
 835 #define DEFINE_WAIT(name) DEFINE_WAIT_FUNC(name, autoremove_wake_function)
 836
 837 #define DEFINE_WAIT_BIT(name, word, bit)                                \
 838         struct wait_bit_queue name = {                                  \
 839                 .key = __WAIT_BIT_KEY_INITIALIZER(word, bit),           \
 840                 .wait   = {                                             \
 841                         .private        = current,                      \
 842                         .func           = wake_bit_function,            \
 843                         .task_list      =                               \
 844                                 LIST_HEAD_INIT((name).wait.task_list),  \
 845                 },                                                      \
 846         }
 847
 848 #define init_wait(wait)                                                 \
 849         do {                                                            \
 850                 (wait)->private = current;                              \
 851                 (wait)->func = autoremove_wake_function;                \
 852                 INIT_LIST_HEAD(&(wait)->task_list);                     \
 853                 (wait)->flags = 0;                                      \
 854         } while (0)
 855
 856 /**
 857  * wait_on_bit - wait for a bit to be cleared
 858  * @word: the word being waited on, a kernel virtual address
 859  * @bit: the bit of the word being waited on
 860  * @action: the function used to sleep, which may take special actions
 861  * @mode: the task state to sleep in
 862  *
 863  * There is a standard hashed waitqueue table for generic use. This
 864  * is the part of the hashtable's accessor API that waits on a bit.
 865  * For instance, if one were to have waiters on a bitflag, one would
 866  * call wait_on_bit() in threads waiting for the bit to clear.
 867  * One uses wait_on_bit() where one is waiting for the bit to clear,
 868  * but has no intention of setting it.
 869  */
 870 static inline int
 871 wait_on_bit(void *word, int bit, int (*action)(void *), unsigned mode)
 872 {
 873         if (!test_bit(bit, word))
 874                 return 0;
 875         return out_of_line_wait_on_bit(word, bit, action, mode);
 876 }
 877
 878 /**
 879  * wait_on_bit_lock - wait for a bit to be cleared, when wanting to set it
 880  * @word: the word being waited on, a kernel virtual address
 881  * @bit: the bit of the word being waited on
 882  * @action: the function used to sleep, which may take special actions
 883  * @mode: the task state to sleep in
 884  *
 885  * There is a standard hashed waitqueue table for generic use. This
 886  * is the part of the hashtable's accessor API that waits on a bit
 887  * when one intends to set it, for instance, trying to lock bitflags.
 888  * For instance, if one were to have waiters trying to set bitflag
 889  * and waiting for it to clear before setting it, one would call
 890  * wait_on_bit() in threads waiting to be able to set the bit.
 891  * One uses wait_on_bit_lock() where one is waiting for the bit to
 892  * clear with the intention of setting it, and when done, clearing it.
 893  */
 894 static inline int
 895 wait_on_bit_lock(void *word, int bit, int (*action)(void *), unsigned mode)
 896 {
 897         if (!test_and_set_bit(bit, word))
 898                 return 0;
 899         return out_of_line_wait_on_bit_lock(word, bit, action, mode);
 900 }
 901
 902 /**
 903  * wait_on_atomic_t - Wait for an atomic_t to become 0
 904  * @val: The atomic value being waited on, a kernel virtual address
 905  * @action: the function used to sleep, which may take special actions
 906  * @mode: the task state to sleep in
 907  *
 908  * Wait for an atomic_t to become 0.  We abuse the bit-wait waitqueue table for
 909  * the purpose of getting a waitqueue, but we set the key to a bit number
 910  * outside of the target 'word'.
 911  */
 912 static inline
 913 int wait_on_atomic_t(atomic_t *val, int (*action)(atomic_t *), unsigned mode)
 914 {
 915         if (atomic_read(val) == 0)
 916                 return 0;
 917         return out_of_line_wait_on_atomic_t(val, action, mode);
 918 }
 919
 920 #endif /* _LINUX_WAIT_H */