include/linux/wait.h

   1 #ifndef _LINUX_WAIT_H
   2 #define _LINUX_WAIT_H
   3
   4
   5 #include <linux/list.h>
   6 #include <linux/stddef.h>
   7 #include <linux/spinlock.h>
   8 #include <asm/current.h>
   9 #include <uapi/linux/wait.h>
  10
  11 typedef struct __wait_queue wait_queue_t;
  12 typedef int (*wait_queue_func_t)(wait_queue_t *wait, unsigned mode, int flags, void *key);
  13 int default_wake_function(wait_queue_t *wait, unsigned mode, int flags, void *key);
  14
  15 struct __wait_queue {
  16         unsigned int flags;
  17 #define WQ_FLAG_EXCLUSIVE       0x01
  18         void *private;
  19         wait_queue_func_t func;
  20         struct list_head task_list;
  21 };
  22
  23 struct wait_bit_key {
  24         void *flags;
  25         int bit_nr;
  26 #define WAIT_ATOMIC_T_BIT_NR -1
  27 };
  28
  29 struct wait_bit_queue {
  30         struct wait_bit_key key;
  31         wait_queue_t wait;
  32 };
  33
  34 struct __wait_queue_head {
  35         spinlock_t lock;
  36         struct list_head task_list;
  37 };
  38 typedef struct __wait_queue_head wait_queue_head_t;
  39
  40 struct task_struct;
  41
  42 /*
  43  * Macros for declaration and initialisaton of the datatypes
  44  */
  45
  46 #define __WAITQUEUE_INITIALIZER(name, tsk) {                            \
  47         .private        = tsk,                                          \
  48         .func           = default_wake_function,                        \
  49         .task_list      = { NULL, NULL } }
  50
  51 #define DECLARE_WAITQUEUE(name, tsk)                                    \
  52         wait_queue_t name = __WAITQUEUE_INITIALIZER(name, tsk)
  53
  54 #define __WAIT_QUEUE_HEAD_INITIALIZER(name) {                           \
  55         .lock           = __SPIN_LOCK_UNLOCKED(name.lock),              \
  56         .task_list      = { &(name).task_list, &(name).task_list } }
  57
  58 #define DECLARE_WAIT_QUEUE_HEAD(name) \
  59         wait_queue_head_t name = __WAIT_QUEUE_HEAD_INITIALIZER(name)
  60
  61 #define __WAIT_BIT_KEY_INITIALIZER(word, bit)                           \
  62         { .flags = word, .bit_nr = bit, }
  63
  64 #define __WAIT_ATOMIC_T_KEY_INITIALIZER(p)                              \
  65         { .flags = p, .bit_nr = WAIT_ATOMIC_T_BIT_NR, }
  66
  67 extern void __init_waitqueue_head(wait_queue_head_t *q, const char *name, struct lock_class_key *);
  68
  69 #define init_waitqueue_head(q)                          \
  70         do {                                            \
  71                 static struct lock_class_key __key;     \
  72                                                         \
  73                 __init_waitqueue_head((q), #q, &__key); \
  74         } while (0)
  75
  76 #ifdef CONFIG_LOCKDEP
  77 # define __WAIT_QUEUE_HEAD_INIT_ONSTACK(name) \
  78         ({ init_waitqueue_head(&name); name; })
  79 # define DECLARE_WAIT_QUEUE_HEAD_ONSTACK(name) \
  80         wait_queue_head_t name = __WAIT_QUEUE_HEAD_INIT_ONSTACK(name)
  81 #else
  82 # define DECLARE_WAIT_QUEUE_HEAD_ONSTACK(name) DECLARE_WAIT_QUEUE_HEAD(name)
  83 #endif
  84
  85 static inline void init_waitqueue_entry(wait_queue_t *q, struct task_struct *p)
  86 {
  87         q->flags = 0;
  88         q->private = p;
  89         q->func = default_wake_function;
  90 }
  91
  92 static inline void init_waitqueue_func_entry(wait_queue_t *q,
  93                                         wait_queue_func_t func)
  94 {
  95         q->flags = 0;
  96         q->private = NULL;
  97         q->func = func;
  98 }
  99
 100 static inline int waitqueue_active(wait_queue_head_t *q)
 101 {
 102         return !list_empty(&q->task_list);
 103 }
 104
 105 extern void add_wait_queue(wait_queue_head_t *q, wait_queue_t *wait);
 106 extern void add_wait_queue_exclusive(wait_queue_head_t *q, wait_queue_t *wait);
 107 extern void remove_wait_queue(wait_queue_head_t *q, wait_queue_t *wait);
 108
 109 static inline void __add_wait_queue(wait_queue_head_t *head, wait_queue_t *new)
 110 {
 111         list_add(&new->task_list, &head->task_list);
 112 }
 113
 114 /*
 115  * Used for wake-one threads:
 116  */
 117 static inline void __add_wait_queue_exclusive(wait_queue_head_t *q,
 118                                               wait_queue_t *wait)
 119 {
 120         wait->flags |= WQ_FLAG_EXCLUSIVE;
 121         __add_wait_queue(q, wait);
 122 }
 123
 124 static inline void __add_wait_queue_tail(wait_queue_head_t *head,
 125                                          wait_queue_t *new)
 126 {
 127         list_add_tail(&new->task_list, &head->task_list);
 128 }
 129
 130 static inline void __add_wait_queue_tail_exclusive(wait_queue_head_t *q,
 131                                               wait_queue_t *wait)
 132 {
 133         wait->flags |= WQ_FLAG_EXCLUSIVE;
 134         __add_wait_queue_tail(q, wait);
 135 }
 136
 137 static inline void __remove_wait_queue(wait_queue_head_t *head,
 138                                                         wait_queue_t *old)
 139 {
 140         list_del(&old->task_list);
 141 }
 142
 143 void __wake_up(wait_queue_head_t *q, unsigned int mode, int nr, void *key);
 144 void __wake_up_locked_key(wait_queue_head_t *q, unsigned int mode, void *key);
 145 void __wake_up_sync_key(wait_queue_head_t *q, unsigned int mode, int nr,
 146                         void *key);
 147 void __wake_up_locked(wait_queue_head_t *q, unsigned int mode, int nr);
 148 void __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr);
 149 void __wake_up_bit(wait_queue_head_t *, void *, int);
 150 int __wait_on_bit(wait_queue_head_t *, struct wait_bit_queue *, int (*)(void *), unsigned);
 151 int __wait_on_bit_lock(wait_queue_head_t *, struct wait_bit_queue *, int (*)(void *), unsigned);
 152 void wake_up_bit(void *, int);
 153 void wake_up_atomic_t(atomic_t *);
 154 int out_of_line_wait_on_bit(void *, int, int (*)(void *), unsigned);
 155 int out_of_line_wait_on_bit_lock(void *, int, int (*)(void *), unsigned);
 156 int out_of_line_wait_on_atomic_t(atomic_t *, int (*)(atomic_t *), unsigned);
 157 wait_queue_head_t *bit_waitqueue(void *, int);
 158
 159 #define wake_up(x)                      __wake_up(x, TASK_NORMAL, 1, NULL)
 160 #define wake_up_nr(x, nr)               __wake_up(x, TASK_NORMAL, nr, NULL)
 161 #define wake_up_all(x)                  __wake_up(x, TASK_NORMAL, 0, NULL)
 162 #define wake_up_locked(x)               __wake_up_locked((x), TASK_NORMAL, 1)
 163 #define wake_up_all_locked(x)           __wake_up_locked((x), TASK_NORMAL, 0)
 164
 165 #define wake_up_interruptible(x)        __wake_up(x, TASK_INTERRUPTIBLE, 1, NULL)
 166 #define wake_up_interruptible_nr(x, nr) __wake_up(x, TASK_INTERRUPTIBLE, nr, NULL)
 167 #define wake_up_interruptible_all(x)    __wake_up(x, TASK_INTERRUPTIBLE, 0, NULL)
 168 #define wake_up_interruptible_sync(x)   __wake_up_sync((x), TASK_INTERRUPTIBLE, 1)
 169
 170 /*
 171  * Wakeup macros to be used to report events to the targets.
 172  */
 173 #define wake_up_poll(x, m)                              \
 174         __wake_up(x, TASK_NORMAL, 1, (void *) (m))
 175 #define wake_up_locked_poll(x, m)                               \
 176         __wake_up_locked_key((x), TASK_NORMAL, (void *) (m))
 177 #define wake_up_interruptible_poll(x, m)                        \
 178         __wake_up(x, TASK_INTERRUPTIBLE, 1, (void *) (m))
 179 #define wake_up_interruptible_sync_poll(x, m)                           \
 180         __wake_up_sync_key((x), TASK_INTERRUPTIBLE, 1, (void *) (m))
 181
 182 #define __wait_event(wq, condition)                                     \
 183 do {                                                                    \
 184         DEFINE_WAIT(__wait);                                            \
 185                                                                         \
 186         for (;;) {                                                      \
 187                 prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE);    \
 188                 if (condition)                                          \
 189                         break;                                          \
 190                 schedule();                                             \
 191         }                                                               \
 192         finish_wait(&wq, &__wait);                                      \
 193 } while (0)
 194
 195 /**
 196  * wait_event - sleep until a condition gets true
 197  * @wq: the waitqueue to wait on
 198  * @condition: a C expression for the event to wait for
 199  *
 200  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 201  * @condition evaluates to true. The @condition is checked each time
 202  * the waitqueue @wq is woken up.
 203  *
 204  * wake_up() has to be called after changing any variable that could
 205  * change the result of the wait condition.
 206  */
 207 #define wait_event(wq, condition)                                       \
 208 do {                                                                    \
 209         if (condition)                                                  \
 210                 break;                                                  \
 211         __wait_event(wq, condition);                                    \
 212 } while (0)
 213
 214 #define __wait_event_timeout(wq, condition, ret)                        \
 215 do {                                                                    \
 216         DEFINE_WAIT(__wait);                                            \
 217                                                                         \
 218         for (;;) {                                                      \
 219                 prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE);    \
 220                 if (condition)                                          \
 221                         break;                                          \
 222                 ret = schedule_timeout(ret);                            \
 223                 if (!ret)                                               \
 224                         break;                                          \
 225         }                                                               \
 226         if (!ret && (condition))                                        \
 227                 ret = 1;                                                \
 228         finish_wait(&wq, &__wait);                                      \
 229 } while (0)
 230
 231 /**
 232  * wait_event_timeout - sleep until a condition gets true or a timeout elapses
 233  * @wq: the waitqueue to wait on
 234  * @condition: a C expression for the event to wait for
 235  * @timeout: timeout, in jiffies
 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  * The function returns 0 if the @timeout elapsed, or the remaining
 245  * jiffies (at least 1) if the @condition evaluated to %true before
 246  * the @timeout elapsed.
 247  */
 248 #define wait_event_timeout(wq, condition, timeout)                      \
 249 ({                                                                      \
 250         long __ret = timeout;                                           \
 251         if (!(condition))                                               \
 252                 __wait_event_timeout(wq, condition, __ret);             \
 253         __ret;                                                          \
 254 })
 255
 256 #define __wait_event_cmd(wq, condition, cmd1, cmd2)                     \
 257 do {                                                                    \
 258         DEFINE_WAIT(__wait);                                            \
 259                                                                         \
 260         for (;;) {                                                      \
 261                 prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE);    \
 262                 if (condition)                                          \
 263                         break;                                          \
 264                 cmd1;                                                   \
 265                 schedule();                                             \
 266                 cmd2;                                                   \
 267         }                                                               \
 268         finish_wait(&wq, &__wait);                                      \
 269 } while (0)
 270
 271 /**
 272  * wait_event_cmd - sleep until a condition gets true
 273  * @wq: the waitqueue to wait on
 274  * @condition: a C expression for the event to wait for
 275  * cmd1: the command will be executed before sleep
 276  * cmd2: the command will be executed after sleep
 277  *
 278  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 279  * @condition evaluates to true. The @condition is checked each time
 280  * the waitqueue @wq is woken up.
 281  *
 282  * wake_up() has to be called after changing any variable that could
 283  * change the result of the wait condition.
 284  */
 285 #define wait_event_cmd(wq, condition, cmd1, cmd2)                       \
 286 do {                                                                    \
 287         if (condition)                                                  \
 288                 break;                                                  \
 289         __wait_event_cmd(wq, condition, cmd1, cmd2);                    \
 290 } while (0)
 291
 292 #define __wait_event_interruptible(wq, condition, ret)                  \
 293 do {                                                                    \
 294         DEFINE_WAIT(__wait);                                            \
 295                                                                         \
 296         for (;;) {                                                      \
 297                 prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE);      \
 298                 if (condition)                                          \
 299                         break;                                          \
 300                 if (!signal_pending(current)) {                         \
 301                         schedule();                                     \
 302                         continue;                                       \
 303                 }                                                       \
 304                 ret = -ERESTARTSYS;                                     \
 305                 break;                                                  \
 306         }                                                               \
 307         finish_wait(&wq, &__wait);                                      \
 308 } while (0)
 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                 __wait_event_interruptible(wq, condition, __ret);       \
 330         __ret;                                                          \
 331 })
 332
 333 #define __wait_event_interruptible_timeout(wq, condition, ret)          \
 334 do {                                                                    \
 335         DEFINE_WAIT(__wait);                                            \
 336                                                                         \
 337         for (;;) {                                                      \
 338                 prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE);      \
 339                 if (condition)                                          \
 340                         break;                                          \
 341                 if (!signal_pending(current)) {                         \
 342                         ret = schedule_timeout(ret);                    \
 343                         if (!ret)                                       \
 344                                 break;                                  \
 345                         continue;                                       \
 346                 }                                                       \
 347                 ret = -ERESTARTSYS;                                     \
 348                 break;                                                  \
 349         }                                                               \
 350         if (!ret && (condition))                                        \
 351                 ret = 1;                                                \
 352         finish_wait(&wq, &__wait);                                      \
 353 } while (0)
 354
 355 /**
 356  * wait_event_interruptible_timeout - sleep until a condition gets true or a timeout elapses
 357  * @wq: the waitqueue to wait on
 358  * @condition: a C expression for the event to wait for
 359  * @timeout: timeout, in jiffies
 360  *
 361  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 362  * @condition evaluates to true or a signal is received.
 363  * The @condition is checked each time the waitqueue @wq is woken up.
 364  *
 365  * wake_up() has to be called after changing any variable that could
 366  * change the result of the wait condition.
 367  *
 368  * Returns:
 369  * 0 if the @timeout elapsed, -%ERESTARTSYS if it was interrupted by
 370  * a signal, or the remaining jiffies (at least 1) if the @condition
 371  * evaluated to %true before the @timeout elapsed.
 372  */
 373 #define wait_event_interruptible_timeout(wq, condition, timeout)        \
 374 ({                                                                      \
 375         long __ret = timeout;                                           \
 376         if (!(condition))                                               \
 377                 __wait_event_interruptible_timeout(wq, condition, __ret); \
 378         __ret;                                                          \
 379 })
 380
 381 #define __wait_event_hrtimeout(wq, condition, timeout, state)           \
 382 ({                                                                      \
 383         int __ret = 0;                                                  \
 384         DEFINE_WAIT(__wait);                                            \
 385         struct hrtimer_sleeper __t;                                     \
 386                                                                         \
 387         hrtimer_init_on_stack(&__t.timer, CLOCK_MONOTONIC,              \
 388                               HRTIMER_MODE_REL);                        \
 389         hrtimer_init_sleeper(&__t, current);                            \
 390         if ((timeout).tv64 != KTIME_MAX)                                \
 391                 hrtimer_start_range_ns(&__t.timer, timeout,             \
 392                                        current->timer_slack_ns,         \
 393                                        HRTIMER_MODE_REL);               \
 394                                                                         \
 395         for (;;) {                                                      \
 396                 prepare_to_wait(&wq, &__wait, state);                   \
 397                 if (condition)                                          \
 398                         break;                                          \
 399                 if (state == TASK_INTERRUPTIBLE &&                      \
 400                     signal_pending(current)) {                          \
 401                         __ret = -ERESTARTSYS;                           \
 402                         break;                                          \
 403                 }                                                       \
 404                 if (!__t.task) {                                        \
 405                         __ret = -ETIME;                                 \
 406                         break;                                          \
 407                 }                                                       \
 408                 schedule();                                             \
 409         }                                                               \
 410                                                                         \
 411         hrtimer_cancel(&__t.timer);                                     \
 412         destroy_hrtimer_on_stack(&__t.timer);                           \
 413         finish_wait(&wq, &__wait);                                      \
 414         __ret;                                                          \
 415 })
 416
 417 /**
 418  * wait_event_hrtimeout - sleep until a condition gets true or a timeout elapses
 419  * @wq: the waitqueue to wait on
 420  * @condition: a C expression for the event to wait for
 421  * @timeout: timeout, as a ktime_t
 422  *
 423  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 424  * @condition evaluates to true or a signal is received.
 425  * The @condition is checked each time the waitqueue @wq is woken up.
 426  *
 427  * wake_up() has to be called after changing any variable that could
 428  * change the result of the wait condition.
 429  *
 430  * The function returns 0 if @condition became true, or -ETIME if the timeout
 431  * elapsed.
 432  */
 433 #define wait_event_hrtimeout(wq, condition, timeout)                    \
 434 ({                                                                      \
 435         int __ret = 0;                                                  \
 436         if (!(condition))                                               \
 437                 __ret = __wait_event_hrtimeout(wq, condition, timeout,  \
 438                                                TASK_UNINTERRUPTIBLE);   \
 439         __ret;                                                          \
 440 })
 441
 442 /**
 443  * wait_event_interruptible_hrtimeout - sleep until a condition gets true or a timeout elapses
 444  * @wq: the waitqueue to wait on
 445  * @condition: a C expression for the event to wait for
 446  * @timeout: timeout, as a ktime_t
 447  *
 448  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 449  * @condition evaluates to true or a signal is received.
 450  * The @condition is checked each time the waitqueue @wq is woken up.
 451  *
 452  * wake_up() has to be called after changing any variable that could
 453  * change the result of the wait condition.
 454  *
 455  * The function returns 0 if @condition became true, -ERESTARTSYS if it was
 456  * interrupted by a signal, or -ETIME if the timeout elapsed.
 457  */
 458 #define wait_event_interruptible_hrtimeout(wq, condition, timeout)      \
 459 ({                                                                      \
 460         long __ret = 0;                                                 \
 461         if (!(condition))                                               \
 462                 __ret = __wait_event_hrtimeout(wq, condition, timeout,  \
 463                                                TASK_INTERRUPTIBLE);     \
 464         __ret;                                                          \
 465 })
 466
 467 #define __wait_event_interruptible_exclusive(wq, condition, ret)        \
 468 do {                                                                    \
 469         DEFINE_WAIT(__wait);                                            \
 470                                                                         \
 471         for (;;) {                                                      \
 472                 prepare_to_wait_exclusive(&wq, &__wait,                 \
 473                                         TASK_INTERRUPTIBLE);            \
 474                 if (condition) {                                        \
 475                         finish_wait(&wq, &__wait);                      \
 476                         break;                                          \
 477                 }                                                       \
 478                 if (!signal_pending(current)) {                         \
 479                         schedule();                                     \
 480                         continue;                                       \
 481                 }                                                       \
 482                 ret = -ERESTARTSYS;                                     \
 483                 abort_exclusive_wait(&wq, &__wait,                      \
 484                                 TASK_INTERRUPTIBLE, NULL);              \
 485                 break;                                                  \
 486         }                                                               \
 487 } while (0)
 488
 489 #define wait_event_interruptible_exclusive(wq, condition)               \
 490 ({                                                                      \
 491         int __ret = 0;                                                  \
 492         if (!(condition))                                               \
 493                 __wait_event_interruptible_exclusive(wq, condition, __ret);\
 494         __ret;                                                          \
 495 })
 496
 497
 498 #define __wait_event_interruptible_locked(wq, condition, exclusive, irq) \
 499 ({                                                                      \
 500         int __ret = 0;                                                  \
 501         DEFINE_WAIT(__wait);                                            \
 502         if (exclusive)                                                  \
 503                 __wait.flags |= WQ_FLAG_EXCLUSIVE;                      \
 504         do {                                                            \
 505                 if (likely(list_empty(&__wait.task_list)))              \
 506                         __add_wait_queue_tail(&(wq), &__wait);          \
 507                 set_current_state(TASK_INTERRUPTIBLE);                  \
 508                 if (signal_pending(current)) {                          \
 509                         __ret = -ERESTARTSYS;                           \
 510                         break;                                          \
 511                 }                                                       \
 512                 if (irq)                                                \
 513                         spin_unlock_irq(&(wq).lock);                    \
 514                 else                                                    \
 515                         spin_unlock(&(wq).lock);                        \
 516                 schedule();                                             \
 517                 if (irq)                                                \
 518                         spin_lock_irq(&(wq).lock);                      \
 519                 else                                                    \
 520                         spin_lock(&(wq).lock);                          \
 521         } while (!(condition));                                         \
 522         __remove_wait_queue(&(wq), &__wait);                            \
 523         __set_current_state(TASK_RUNNING);                              \
 524         __ret;                                                          \
 525 })
 526
 527
 528 /**
 529  * wait_event_interruptible_locked - sleep until a condition gets true
 530  * @wq: the waitqueue to wait on
 531  * @condition: a C expression for the event to wait for
 532  *
 533  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 534  * @condition evaluates to true or a signal is received.
 535  * The @condition is checked each time the waitqueue @wq is woken up.
 536  *
 537  * It must be called with wq.lock being held.  This spinlock is
 538  * unlocked while sleeping but @condition testing is done while lock
 539  * is held and when this macro exits the lock is held.
 540  *
 541  * The lock is locked/unlocked using spin_lock()/spin_unlock()
 542  * functions which must match the way they are locked/unlocked outside
 543  * of this macro.
 544  *
 545  * wake_up_locked() has to be called after changing any variable that could
 546  * change the result of the wait condition.
 547  *
 548  * The function will return -ERESTARTSYS if it was interrupted by a
 549  * signal and 0 if @condition evaluated to true.
 550  */
 551 #define wait_event_interruptible_locked(wq, condition)                  \
 552         ((condition)                                                    \
 553          ? 0 : __wait_event_interruptible_locked(wq, condition, 0, 0))
 554
 555 /**
 556  * wait_event_interruptible_locked_irq - sleep until a condition gets true
 557  * @wq: the waitqueue to wait on
 558  * @condition: a C expression for the event to wait for
 559  *
 560  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 561  * @condition evaluates to true or a signal is received.
 562  * The @condition is checked each time the waitqueue @wq is woken up.
 563  *
 564  * It must be called with wq.lock being held.  This spinlock is
 565  * unlocked while sleeping but @condition testing is done while lock
 566  * is held and when this macro exits the lock is held.
 567  *
 568  * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq()
 569  * functions which must match the way they are locked/unlocked outside
 570  * of this macro.
 571  *
 572  * wake_up_locked() has to be called after changing any variable that could
 573  * change the result of the wait condition.
 574  *
 575  * The function will return -ERESTARTSYS if it was interrupted by a
 576  * signal and 0 if @condition evaluated to true.
 577  */
 578 #define wait_event_interruptible_locked_irq(wq, condition)              \
 579         ((condition)                                                    \
 580          ? 0 : __wait_event_interruptible_locked(wq, condition, 0, 1))
 581
 582 /**
 583  * wait_event_interruptible_exclusive_locked - sleep exclusively until a condition gets true
 584  * @wq: the waitqueue to wait on
 585  * @condition: a C expression for the event to wait for
 586  *
 587  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 588  * @condition evaluates to true or a signal is received.
 589  * The @condition is checked each time the waitqueue @wq is woken up.
 590  *
 591  * It must be called with wq.lock being held.  This spinlock is
 592  * unlocked while sleeping but @condition testing is done while lock
 593  * is held and when this macro exits the lock is held.
 594  *
 595  * The lock is locked/unlocked using spin_lock()/spin_unlock()
 596  * functions which must match the way they are locked/unlocked outside
 597  * of this macro.
 598  *
 599  * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
 600  * set thus when other process waits process on the list if this
 601  * process is awaken further processes are not considered.
 602  *
 603  * wake_up_locked() has to be called after changing any variable that could
 604  * change the result of the wait condition.
 605  *
 606  * The function will return -ERESTARTSYS if it was interrupted by a
 607  * signal and 0 if @condition evaluated to true.
 608  */
 609 #define wait_event_interruptible_exclusive_locked(wq, condition)        \
 610         ((condition)                                                    \
 611          ? 0 : __wait_event_interruptible_locked(wq, condition, 1, 0))
 612
 613 /**
 614  * wait_event_interruptible_exclusive_locked_irq - sleep until a condition gets true
 615  * @wq: the waitqueue to wait on
 616  * @condition: a C expression for the event to wait for
 617  *
 618  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 619  * @condition evaluates to true or a signal is received.
 620  * The @condition is checked each time the waitqueue @wq is woken up.
 621  *
 622  * It must be called with wq.lock being held.  This spinlock is
 623  * unlocked while sleeping but @condition testing is done while lock
 624  * is held and when this macro exits the lock is held.
 625  *
 626  * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq()
 627  * functions which must match the way they are locked/unlocked outside
 628  * of this macro.
 629  *
 630  * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
 631  * set thus when other process waits process on the list if this
 632  * process is awaken further processes are not considered.
 633  *
 634  * wake_up_locked() has to be called after changing any variable that could
 635  * change the result of the wait condition.
 636  *
 637  * The function will return -ERESTARTSYS if it was interrupted by a
 638  * signal and 0 if @condition evaluated to true.
 639  */
 640 #define wait_event_interruptible_exclusive_locked_irq(wq, condition)    \
 641         ((condition)                                                    \
 642          ? 0 : __wait_event_interruptible_locked(wq, condition, 1, 1))
 643
 644
 645
 646 #define __wait_event_killable(wq, condition, ret)                       \
 647 do {                                                                    \
 648         DEFINE_WAIT(__wait);                                            \
 649                                                                         \
 650         for (;;) {                                                      \
 651                 prepare_to_wait(&wq, &__wait, TASK_KILLABLE);           \
 652                 if (condition)                                          \
 653                         break;                                          \
 654                 if (!fatal_signal_pending(current)) {                   \
 655                         schedule();                                     \
 656                         continue;                                       \
 657                 }                                                       \
 658                 ret = -ERESTARTSYS;                                     \
 659                 break;                                                  \
 660         }                                                               \
 661         finish_wait(&wq, &__wait);                                      \
 662 } while (0)
 663
 664 /**
 665  * wait_event_killable - sleep until a condition gets true
 666  * @wq: the waitqueue to wait on
 667  * @condition: a C expression for the event to wait for
 668  *
 669  * The process is put to sleep (TASK_KILLABLE) until the
 670  * @condition evaluates to true or a signal is received.
 671  * The @condition is checked each time the waitqueue @wq is woken up.
 672  *
 673  * wake_up() has to be called after changing any variable that could
 674  * change the result of the wait condition.
 675  *
 676  * The function will return -ERESTARTSYS if it was interrupted by a
 677  * signal and 0 if @condition evaluated to true.
 678  */
 679 #define wait_event_killable(wq, condition)                              \
 680 ({                                                                      \
 681         int __ret = 0;                                                  \
 682         if (!(condition))                                               \
 683                 __wait_event_killable(wq, condition, __ret);            \
 684         __ret;                                                          \
 685 })
 686
 687
 688 #define __wait_event_lock_irq(wq, condition, lock, cmd)                 \
 689 do {                                                                    \
 690         DEFINE_WAIT(__wait);                                            \
 691                                                                         \
 692         for (;;) {                                                      \
 693                 prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE);    \
 694                 if (condition)                                          \
 695                         break;                                          \
 696                 spin_unlock_irq(&lock);                                 \
 697                 cmd;                                                    \
 698                 schedule();                                             \
 699                 spin_lock_irq(&lock);                                   \
 700         }                                                               \
 701         finish_wait(&wq, &__wait);                                      \
 702 } while (0)
 703
 704 /**
 705  * wait_event_lock_irq_cmd - sleep until a condition gets true. The
 706  *                           condition is checked under the lock. This
 707  *                           is expected to be called with the lock
 708  *                           taken.
 709  * @wq: the waitqueue to wait on
 710  * @condition: a C expression for the event to wait for
 711  * @lock: a locked spinlock_t, which will be released before cmd
 712  *        and schedule() and reacquired afterwards.
 713  * @cmd: a command which is invoked outside the critical section before
 714  *       sleep
 715  *
 716  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 717  * @condition evaluates to true. The @condition is checked each time
 718  * the waitqueue @wq is woken up.
 719  *
 720  * wake_up() has to be called after changing any variable that could
 721  * change the result of the wait condition.
 722  *
 723  * This is supposed to be called while holding the lock. The lock is
 724  * dropped before invoking the cmd and going to sleep and is reacquired
 725  * afterwards.
 726  */
 727 #define wait_event_lock_irq_cmd(wq, condition, lock, cmd)               \
 728 do {                                                                    \
 729         if (condition)                                                  \
 730                 break;                                                  \
 731         __wait_event_lock_irq(wq, condition, lock, cmd);                \
 732 } while (0)
 733
 734 /**
 735  * wait_event_lock_irq - sleep until a condition gets true. The
 736  *                       condition is checked under the lock. This
 737  *                       is expected to be called with the lock
 738  *                       taken.
 739  * @wq: the waitqueue to wait on
 740  * @condition: a C expression for the event to wait for
 741  * @lock: a locked spinlock_t, which will be released before schedule()
 742  *        and reacquired afterwards.
 743  *
 744  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 745  * @condition evaluates to true. The @condition is checked each time
 746  * the waitqueue @wq is woken up.
 747  *
 748  * wake_up() has to be called after changing any variable that could
 749  * change the result of the wait condition.
 750  *
 751  * This is supposed to be called while holding the lock. The lock is
 752  * dropped before going to sleep and is reacquired afterwards.
 753  */
 754 #define wait_event_lock_irq(wq, condition, lock)                        \
 755 do {                                                                    \
 756         if (condition)                                                  \
 757                 break;                                                  \
 758         __wait_event_lock_irq(wq, condition, lock, );                   \
 759 } while (0)
 760
 761
 762 #define __wait_event_interruptible_lock_irq(wq, condition,              \
 763                                             lock, ret, cmd)             \
 764 do {                                                                    \
 765         DEFINE_WAIT(__wait);                                            \
 766                                                                         \
 767         for (;;) {                                                      \
 768                 prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE);      \
 769                 if (condition)                                          \
 770                         break;                                          \
 771                 if (signal_pending(current)) {                          \
 772                         ret = -ERESTARTSYS;                             \
 773                         break;                                          \
 774                 }                                                       \
 775                 spin_unlock_irq(&lock);                                 \
 776                 cmd;                                                    \
 777                 schedule();                                             \
 778                 spin_lock_irq(&lock);                                   \
 779         }                                                               \
 780         finish_wait(&wq, &__wait);                                      \
 781 } while (0)
 782
 783 /**
 784  * wait_event_interruptible_lock_irq_cmd - sleep until a condition gets true.
 785  *              The condition is checked under the lock. This is expected to
 786  *              be called with the lock taken.
 787  * @wq: the waitqueue to wait on
 788  * @condition: a C expression for the event to wait for
 789  * @lock: a locked spinlock_t, which will be released before cmd and
 790  *        schedule() and reacquired afterwards.
 791  * @cmd: a command which is invoked outside the critical section before
 792  *       sleep
 793  *
 794  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 795  * @condition evaluates to true or a 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 invoking the cmd and going to sleep and is reacquired
 803  * afterwards.
 804  *
 805  * The macro will return -ERESTARTSYS if it was interrupted by a signal
 806  * and 0 if @condition evaluated to true.
 807  */
 808 #define wait_event_interruptible_lock_irq_cmd(wq, condition, lock, cmd) \
 809 ({                                                                      \
 810         int __ret = 0;                                                  \
 811                                                                         \
 812         if (!(condition))                                               \
 813                 __wait_event_interruptible_lock_irq(wq, condition,      \
 814                                                     lock, __ret, cmd);  \
 815         __ret;                                                          \
 816 })
 817
 818 /**
 819  * wait_event_interruptible_lock_irq - sleep until a condition gets true.
 820  *              The condition is checked under the lock. This is expected
 821  *              to be called with the lock taken.
 822  * @wq: the waitqueue to wait on
 823  * @condition: a C expression for the event to wait for
 824  * @lock: a locked spinlock_t, which will be released before schedule()
 825  *        and reacquired afterwards.
 826  *
 827  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 828  * @condition evaluates to true or signal is received. The @condition is
 829  * checked each time the waitqueue @wq is woken up.
 830  *
 831  * wake_up() has to be called after changing any variable that could
 832  * change the result of the wait condition.
 833  *
 834  * This is supposed to be called while holding the lock. The lock is
 835  * dropped before going to sleep and is reacquired afterwards.
 836  *
 837  * The macro will return -ERESTARTSYS if it was interrupted by a signal
 838  * and 0 if @condition evaluated to true.
 839  */
 840 #define wait_event_interruptible_lock_irq(wq, condition, lock)          \
 841 ({                                                                      \
 842         int __ret = 0;                                                  \
 843                                                                         \
 844         if (!(condition))                                               \
 845                 __wait_event_interruptible_lock_irq(wq, condition,      \
 846                                                     lock, __ret, );     \
 847         __ret;                                                          \
 848 })
 849
 850 #define __wait_event_interruptible_lock_irq_timeout(wq, condition,      \
 851                                                     lock, ret)          \
 852 do {                                                                    \
 853         DEFINE_WAIT(__wait);                                            \
 854                                                                         \
 855         for (;;) {                                                      \
 856                 prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE);      \
 857                 if (condition)                                          \
 858                         break;                                          \
 859                 if (signal_pending(current)) {                          \
 860                         ret = -ERESTARTSYS;                             \
 861                         break;                                          \
 862                 }                                                       \
 863                 spin_unlock_irq(&lock);                                 \
 864                 ret = schedule_timeout(ret);                            \
 865                 spin_lock_irq(&lock);                                   \
 866                 if (!ret)                                               \
 867                         break;                                          \
 868         }                                                               \
 869         finish_wait(&wq, &__wait);                                      \
 870 } while (0)
 871
 872 /**
 873  * wait_event_interruptible_lock_irq_timeout - sleep until a condition gets true or a timeout elapses.
 874  *              The condition is checked under the lock. This is expected
 875  *              to be called with the lock taken.
 876  * @wq: the waitqueue to wait on
 877  * @condition: a C expression for the event to wait for
 878  * @lock: a locked spinlock_t, which will be released before schedule()
 879  *        and reacquired afterwards.
 880  * @timeout: timeout, in jiffies
 881  *
 882  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 883  * @condition evaluates to true or signal is received. The @condition is
 884  * checked each time the waitqueue @wq is woken up.
 885  *
 886  * wake_up() has to be called after changing any variable that could
 887  * change the result of the wait condition.
 888  *
 889  * This is supposed to be called while holding the lock. The lock is
 890  * dropped before going to sleep and is reacquired afterwards.
 891  *
 892  * The function returns 0 if the @timeout elapsed, -ERESTARTSYS if it
 893  * was interrupted by a signal, and the remaining jiffies otherwise
 894  * if the condition evaluated to true before the timeout elapsed.
 895  */
 896 #define wait_event_interruptible_lock_irq_timeout(wq, condition, lock,  \
 897                                                   timeout)              \
 898 ({                                                                      \
 899         int __ret = timeout;                                            \
 900                                                                         \
 901         if (!(condition))                                               \
 902                 __wait_event_interruptible_lock_irq_timeout(            \
 903                                         wq, condition, lock, __ret);    \
 904         __ret;                                                          \
 905 })
 906
 907
 908 /*
 909  * These are the old interfaces to sleep waiting for an event.
 910  * They are racy.  DO NOT use them, use the wait_event* interfaces above.
 911  * We plan to remove these interfaces.
 912  */
 913 extern void sleep_on(wait_queue_head_t *q);
 914 extern long sleep_on_timeout(wait_queue_head_t *q,
 915                                       signed long timeout);
 916 extern void interruptible_sleep_on(wait_queue_head_t *q);
 917 extern long interruptible_sleep_on_timeout(wait_queue_head_t *q,
 918                                            signed long timeout);
 919
 920 /*
 921  * Waitqueues which are removed from the waitqueue_head at wakeup time
 922  */
 923 void prepare_to_wait(wait_queue_head_t *q, wait_queue_t *wait, int state);
 924 void prepare_to_wait_exclusive(wait_queue_head_t *q, wait_queue_t *wait, int state);
 925 void finish_wait(wait_queue_head_t *q, wait_queue_t *wait);
 926 void abort_exclusive_wait(wait_queue_head_t *q, wait_queue_t *wait,
 927                         unsigned int mode, void *key);
 928 int autoremove_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 929 int wake_bit_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 930
 931 #define DEFINE_WAIT_FUNC(name, function)                                \
 932         wait_queue_t name = {                                           \
 933                 .private        = current,                              \
 934                 .func           = function,                             \
 935                 .task_list      = LIST_HEAD_INIT((name).task_list),     \
 936         }
 937
 938 #define DEFINE_WAIT(name) DEFINE_WAIT_FUNC(name, autoremove_wake_function)
 939
 940 #define DEFINE_WAIT_BIT(name, word, bit)                                \
 941         struct wait_bit_queue name = {                                  \
 942                 .key = __WAIT_BIT_KEY_INITIALIZER(word, bit),           \
 943                 .wait   = {                                             \
 944                         .private        = current,                      \
 945                         .func           = wake_bit_function,            \
 946                         .task_list      =                               \
 947                                 LIST_HEAD_INIT((name).wait.task_list),  \
 948                 },                                                      \
 949         }
 950
 951 #define init_wait(wait)                                                 \
 952         do {                                                            \
 953                 (wait)->private = current;                              \
 954                 (wait)->func = autoremove_wake_function;                \
 955                 INIT_LIST_HEAD(&(wait)->task_list);                     \
 956                 (wait)->flags = 0;                                      \
 957         } while (0)
 958
 959 /**
 960  * wait_on_bit - wait for a bit to be cleared
 961  * @word: the word being waited on, a kernel virtual address
 962  * @bit: the bit of the word being waited on
 963  * @action: the function used to sleep, which may take special actions
 964  * @mode: the task state to sleep in
 965  *
 966  * There is a standard hashed waitqueue table for generic use. This
 967  * is the part of the hashtable's accessor API that waits on a bit.
 968  * For instance, if one were to have waiters on a bitflag, one would
 969  * call wait_on_bit() in threads waiting for the bit to clear.
 970  * One uses wait_on_bit() where one is waiting for the bit to clear,
 971  * but has no intention of setting it.
 972  */
 973 static inline int wait_on_bit(void *word, int bit,
 974                                 int (*action)(void *), unsigned mode)
 975 {
 976         if (!test_bit(bit, word))
 977                 return 0;
 978         return out_of_line_wait_on_bit(word, bit, action, mode);
 979 }
 980
 981 /**
 982  * wait_on_bit_lock - wait for a bit to be cleared, when wanting to set it
 983  * @word: the word being waited on, a kernel virtual address
 984  * @bit: the bit of the word being waited on
 985  * @action: the function used to sleep, which may take special actions
 986  * @mode: the task state to sleep in
 987  *
 988  * There is a standard hashed waitqueue table for generic use. This
 989  * is the part of the hashtable's accessor API that waits on a bit
 990  * when one intends to set it, for instance, trying to lock bitflags.
 991  * For instance, if one were to have waiters trying to set bitflag
 992  * and waiting for it to clear before setting it, one would call
 993  * wait_on_bit() in threads waiting to be able to set the bit.
 994  * One uses wait_on_bit_lock() where one is waiting for the bit to
 995  * clear with the intention of setting it, and when done, clearing it.
 996  */
 997 static inline int wait_on_bit_lock(void *word, int bit,
 998                                 int (*action)(void *), unsigned mode)
 999 {
1000         if (!test_and_set_bit(bit, word))
1001                 return 0;
1002         return out_of_line_wait_on_bit_lock(word, bit, action, mode);
1003 }
1004
1005 /**
1006  * wait_on_atomic_t - Wait for an atomic_t to become 0
1007  * @val: The atomic value being waited on, a kernel virtual address
1008  * @action: the function used to sleep, which may take special actions
1009  * @mode: the task state to sleep in
1010  *
1011  * Wait for an atomic_t to become 0.  We abuse the bit-wait waitqueue table for
1012  * the purpose of getting a waitqueue, but we set the key to a bit number
1013  * outside of the target 'word'.
1014  */
1015 static inline
1016 int wait_on_atomic_t(atomic_t *val, int (*action)(atomic_t *), unsigned mode)
1017 {
1018         if (atomic_read(val) == 0)
1019                 return 0;
1020         return out_of_line_wait_on_atomic_t(val, action, mode);
1021 }
1022
1023 #endif