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_interruptible(wq, condition, ret)                  \
 257 do {                                                                    \
 258         DEFINE_WAIT(__wait);                                            \
 259                                                                         \
 260         for (;;) {                                                      \
 261                 prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE);      \
 262                 if (condition)                                          \
 263                         break;                                          \
 264                 if (signal_pending(current)) {                          \
 265                         ret = -ERESTARTSYS;                             \
 266                         break;                                          \
 267                 }                                                       \
 268                 schedule();                                             \
 269         }                                                               \
 270         finish_wait(&wq, &__wait);                                      \
 271 } while (0)
 272
 273 /**
 274  * wait_event_interruptible - sleep until a condition gets true
 275  * @wq: the waitqueue to wait on
 276  * @condition: a C expression for the event to wait for
 277  *
 278  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 279  * @condition evaluates to true or a signal is received.
 280  * The @condition is checked each time 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  * The function will return -ERESTARTSYS if it was interrupted by a
 286  * signal and 0 if @condition evaluated to true.
 287  */
 288 #define wait_event_interruptible(wq, condition)                         \
 289 ({                                                                      \
 290         int __ret = 0;                                                  \
 291         if (!(condition))                                               \
 292                 __wait_event_interruptible(wq, condition, __ret);       \
 293         __ret;                                                          \
 294 })
 295
 296 #define __wait_event_interruptible_timeout(wq, condition, ret)          \
 297 do {                                                                    \
 298         DEFINE_WAIT(__wait);                                            \
 299                                                                         \
 300         for (;;) {                                                      \
 301                 prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE);      \
 302                 if (condition)                                          \
 303                         break;                                          \
 304                 if (signal_pending(current)) {                          \
 305                         ret = -ERESTARTSYS;                             \
 306                         break;                                          \
 307                 }                                                       \
 308                 ret = schedule_timeout(ret);                            \
 309                 if (!ret)                                               \
 310                         break;                                          \
 311         }                                                               \
 312         if (!ret && (condition))                                        \
 313                 ret = 1;                                                \
 314         finish_wait(&wq, &__wait);                                      \
 315 } while (0)
 316
 317 /**
 318  * wait_event_interruptible_timeout - sleep until a condition gets true or a timeout elapses
 319  * @wq: the waitqueue to wait on
 320  * @condition: a C expression for the event to wait for
 321  * @timeout: timeout, in jiffies
 322  *
 323  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 324  * @condition evaluates to true or a signal is received.
 325  * The @condition is checked each time the waitqueue @wq is woken up.
 326  *
 327  * wake_up() has to be called after changing any variable that could
 328  * change the result of the wait condition.
 329  *
 330  * Returns:
 331  * 0 if the @timeout elapsed, -%ERESTARTSYS if it was interrupted by
 332  * a signal, or the remaining jiffies (at least 1) if the @condition
 333  * evaluated to %true before the @timeout elapsed.
 334  */
 335 #define wait_event_interruptible_timeout(wq, condition, timeout)        \
 336 ({                                                                      \
 337         long __ret = timeout;                                           \
 338         if (!(condition))                                               \
 339                 __wait_event_interruptible_timeout(wq, condition, __ret); \
 340         __ret;                                                          \
 341 })
 342
 343 #define __wait_event_hrtimeout(wq, condition, timeout, state)           \
 344 ({                                                                      \
 345         int __ret = 0;                                                  \
 346         DEFINE_WAIT(__wait);                                            \
 347         struct hrtimer_sleeper __t;                                     \
 348                                                                         \
 349         hrtimer_init_on_stack(&__t.timer, CLOCK_MONOTONIC,              \
 350                               HRTIMER_MODE_REL);                        \
 351         hrtimer_init_sleeper(&__t, current);                            \
 352         if ((timeout).tv64 != KTIME_MAX)                                \
 353                 hrtimer_start_range_ns(&__t.timer, timeout,             \
 354                                        current->timer_slack_ns,         \
 355                                        HRTIMER_MODE_REL);               \
 356                                                                         \
 357         for (;;) {                                                      \
 358                 prepare_to_wait(&wq, &__wait, state);                   \
 359                 if (condition)                                          \
 360                         break;                                          \
 361                 if (state == TASK_INTERRUPTIBLE &&                      \
 362                     signal_pending(current)) {                          \
 363                         __ret = -ERESTARTSYS;                           \
 364                         break;                                          \
 365                 }                                                       \
 366                 if (!__t.task) {                                        \
 367                         __ret = -ETIME;                                 \
 368                         break;                                          \
 369                 }                                                       \
 370                 schedule();                                             \
 371         }                                                               \
 372                                                                         \
 373         hrtimer_cancel(&__t.timer);                                     \
 374         destroy_hrtimer_on_stack(&__t.timer);                           \
 375         finish_wait(&wq, &__wait);                                      \
 376         __ret;                                                          \
 377 })
 378
 379 /**
 380  * wait_event_hrtimeout - sleep until a condition gets true or a timeout elapses
 381  * @wq: the waitqueue to wait on
 382  * @condition: a C expression for the event to wait for
 383  * @timeout: timeout, as a ktime_t
 384  *
 385  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 386  * @condition evaluates to true or a signal is received.
 387  * The @condition is checked each time the waitqueue @wq is woken up.
 388  *
 389  * wake_up() has to be called after changing any variable that could
 390  * change the result of the wait condition.
 391  *
 392  * The function returns 0 if @condition became true, or -ETIME if the timeout
 393  * elapsed.
 394  */
 395 #define wait_event_hrtimeout(wq, condition, timeout)                    \
 396 ({                                                                      \
 397         int __ret = 0;                                                  \
 398         if (!(condition))                                               \
 399                 __ret = __wait_event_hrtimeout(wq, condition, timeout,  \
 400                                                TASK_UNINTERRUPTIBLE);   \
 401         __ret;                                                          \
 402 })
 403
 404 /**
 405  * wait_event_interruptible_hrtimeout - sleep until a condition gets true or a timeout elapses
 406  * @wq: the waitqueue to wait on
 407  * @condition: a C expression for the event to wait for
 408  * @timeout: timeout, as a ktime_t
 409  *
 410  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 411  * @condition evaluates to true or a signal is received.
 412  * The @condition is checked each time the waitqueue @wq is woken up.
 413  *
 414  * wake_up() has to be called after changing any variable that could
 415  * change the result of the wait condition.
 416  *
 417  * The function returns 0 if @condition became true, -ERESTARTSYS if it was
 418  * interrupted by a signal, or -ETIME if the timeout elapsed.
 419  */
 420 #define wait_event_interruptible_hrtimeout(wq, condition, timeout)      \
 421 ({                                                                      \
 422         long __ret = 0;                                                 \
 423         if (!(condition))                                               \
 424                 __ret = __wait_event_hrtimeout(wq, condition, timeout,  \
 425                                                TASK_INTERRUPTIBLE);     \
 426         __ret;                                                          \
 427 })
 428
 429 #define __wait_event_interruptible_exclusive(wq, condition, ret)        \
 430 do {                                                                    \
 431         DEFINE_WAIT(__wait);                                            \
 432                                                                         \
 433         for (;;) {                                                      \
 434                 prepare_to_wait_exclusive(&wq, &__wait,                 \
 435                                         TASK_INTERRUPTIBLE);            \
 436                 if (condition) {                                        \
 437                         finish_wait(&wq, &__wait);                      \
 438                         break;                                          \
 439                 }                                                       \
 440                 if (signal_pending(current)) {                          \
 441                         ret = -ERESTARTSYS;                             \
 442                         abort_exclusive_wait(&wq, &__wait,              \
 443                                 TASK_INTERRUPTIBLE, NULL);              \
 444                         break;                                          \
 445                 }                                                       \
 446                 schedule();                                             \
 447         }                                                               \
 448 } while (0)
 449
 450 #define wait_event_interruptible_exclusive(wq, condition)               \
 451 ({                                                                      \
 452         int __ret = 0;                                                  \
 453         if (!(condition))                                               \
 454                 __wait_event_interruptible_exclusive(wq, condition, __ret);\
 455         __ret;                                                          \
 456 })
 457
 458
 459 #define __wait_event_interruptible_locked(wq, condition, exclusive, irq) \
 460 ({                                                                      \
 461         int __ret = 0;                                                  \
 462         DEFINE_WAIT(__wait);                                            \
 463         if (exclusive)                                                  \
 464                 __wait.flags |= WQ_FLAG_EXCLUSIVE;                      \
 465         do {                                                            \
 466                 if (likely(list_empty(&__wait.task_list)))              \
 467                         __add_wait_queue_tail(&(wq), &__wait);          \
 468                 set_current_state(TASK_INTERRUPTIBLE);                  \
 469                 if (signal_pending(current)) {                          \
 470                         __ret = -ERESTARTSYS;                           \
 471                         break;                                          \
 472                 }                                                       \
 473                 if (irq)                                                \
 474                         spin_unlock_irq(&(wq).lock);                    \
 475                 else                                                    \
 476                         spin_unlock(&(wq).lock);                        \
 477                 schedule();                                             \
 478                 if (irq)                                                \
 479                         spin_lock_irq(&(wq).lock);                      \
 480                 else                                                    \
 481                         spin_lock(&(wq).lock);                          \
 482         } while (!(condition));                                         \
 483         __remove_wait_queue(&(wq), &__wait);                            \
 484         __set_current_state(TASK_RUNNING);                              \
 485         __ret;                                                          \
 486 })
 487
 488
 489 /**
 490  * wait_event_interruptible_locked - sleep until a condition gets true
 491  * @wq: the waitqueue to wait on
 492  * @condition: a C expression for the event to wait for
 493  *
 494  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 495  * @condition evaluates to true or a signal is received.
 496  * The @condition is checked each time the waitqueue @wq is woken up.
 497  *
 498  * It must be called with wq.lock being held.  This spinlock is
 499  * unlocked while sleeping but @condition testing is done while lock
 500  * is held and when this macro exits the lock is held.
 501  *
 502  * The lock is locked/unlocked using spin_lock()/spin_unlock()
 503  * functions which must match the way they are locked/unlocked outside
 504  * of this macro.
 505  *
 506  * wake_up_locked() has to be called after changing any variable that could
 507  * change the result of the wait condition.
 508  *
 509  * The function will return -ERESTARTSYS if it was interrupted by a
 510  * signal and 0 if @condition evaluated to true.
 511  */
 512 #define wait_event_interruptible_locked(wq, condition)                  \
 513         ((condition)                                                    \
 514          ? 0 : __wait_event_interruptible_locked(wq, condition, 0, 0))
 515
 516 /**
 517  * wait_event_interruptible_locked_irq - sleep until a condition gets true
 518  * @wq: the waitqueue to wait on
 519  * @condition: a C expression for the event to wait for
 520  *
 521  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 522  * @condition evaluates to true or a signal is received.
 523  * The @condition is checked each time the waitqueue @wq is woken up.
 524  *
 525  * It must be called with wq.lock being held.  This spinlock is
 526  * unlocked while sleeping but @condition testing is done while lock
 527  * is held and when this macro exits the lock is held.
 528  *
 529  * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq()
 530  * functions which must match the way they are locked/unlocked outside
 531  * of this macro.
 532  *
 533  * wake_up_locked() has to be called after changing any variable that could
 534  * change the result of the wait condition.
 535  *
 536  * The function will return -ERESTARTSYS if it was interrupted by a
 537  * signal and 0 if @condition evaluated to true.
 538  */
 539 #define wait_event_interruptible_locked_irq(wq, condition)              \
 540         ((condition)                                                    \
 541          ? 0 : __wait_event_interruptible_locked(wq, condition, 0, 1))
 542
 543 /**
 544  * wait_event_interruptible_exclusive_locked - sleep exclusively until a condition gets true
 545  * @wq: the waitqueue to wait on
 546  * @condition: a C expression for the event to wait for
 547  *
 548  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 549  * @condition evaluates to true or a signal is received.
 550  * The @condition is checked each time the waitqueue @wq is woken up.
 551  *
 552  * It must be called with wq.lock being held.  This spinlock is
 553  * unlocked while sleeping but @condition testing is done while lock
 554  * is held and when this macro exits the lock is held.
 555  *
 556  * The lock is locked/unlocked using spin_lock()/spin_unlock()
 557  * functions which must match the way they are locked/unlocked outside
 558  * of this macro.
 559  *
 560  * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
 561  * set thus when other process waits process on the list if this
 562  * process is awaken further processes are not considered.
 563  *
 564  * wake_up_locked() has to be called after changing any variable that could
 565  * change the result of the wait condition.
 566  *
 567  * The function will return -ERESTARTSYS if it was interrupted by a
 568  * signal and 0 if @condition evaluated to true.
 569  */
 570 #define wait_event_interruptible_exclusive_locked(wq, condition)        \
 571         ((condition)                                                    \
 572          ? 0 : __wait_event_interruptible_locked(wq, condition, 1, 0))
 573
 574 /**
 575  * wait_event_interruptible_exclusive_locked_irq - sleep until a condition gets true
 576  * @wq: the waitqueue to wait on
 577  * @condition: a C expression for the event to wait for
 578  *
 579  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 580  * @condition evaluates to true or a signal is received.
 581  * The @condition is checked each time the waitqueue @wq is woken up.
 582  *
 583  * It must be called with wq.lock being held.  This spinlock is
 584  * unlocked while sleeping but @condition testing is done while lock
 585  * is held and when this macro exits the lock is held.
 586  *
 587  * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq()
 588  * functions which must match the way they are locked/unlocked outside
 589  * of this macro.
 590  *
 591  * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
 592  * set thus when other process waits process on the list if this
 593  * process is awaken further processes are not considered.
 594  *
 595  * wake_up_locked() has to be called after changing any variable that could
 596  * change the result of the wait condition.
 597  *
 598  * The function will return -ERESTARTSYS if it was interrupted by a
 599  * signal and 0 if @condition evaluated to true.
 600  */
 601 #define wait_event_interruptible_exclusive_locked_irq(wq, condition)    \
 602         ((condition)                                                    \
 603          ? 0 : __wait_event_interruptible_locked(wq, condition, 1, 1))
 604
 605
 606
 607 #define __wait_event_killable(wq, condition, ret)                       \
 608 do {                                                                    \
 609         DEFINE_WAIT(__wait);                                            \
 610                                                                         \
 611         for (;;) {                                                      \
 612                 prepare_to_wait(&wq, &__wait, TASK_KILLABLE);           \
 613                 if (condition)                                          \
 614                         break;                                          \
 615                 if (!fatal_signal_pending(current)) {                   \
 616                         schedule();                                     \
 617                         continue;                                       \
 618                 }                                                       \
 619                 ret = -ERESTARTSYS;                                     \
 620                 break;                                                  \
 621         }                                                               \
 622         finish_wait(&wq, &__wait);                                      \
 623 } while (0)
 624
 625 /**
 626  * wait_event_killable - sleep until a condition gets true
 627  * @wq: the waitqueue to wait on
 628  * @condition: a C expression for the event to wait for
 629  *
 630  * The process is put to sleep (TASK_KILLABLE) until the
 631  * @condition evaluates to true or a signal is received.
 632  * The @condition is checked each time the waitqueue @wq is woken up.
 633  *
 634  * wake_up() 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_killable(wq, condition)                              \
 641 ({                                                                      \
 642         int __ret = 0;                                                  \
 643         if (!(condition))                                               \
 644                 __wait_event_killable(wq, condition, __ret);            \
 645         __ret;                                                          \
 646 })
 647
 648
 649 #define __wait_event_lock_irq(wq, condition, lock, cmd)                 \
 650 do {                                                                    \
 651         DEFINE_WAIT(__wait);                                            \
 652                                                                         \
 653         for (;;) {                                                      \
 654                 prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE);    \
 655                 if (condition)                                          \
 656                         break;                                          \
 657                 spin_unlock_irq(&lock);                                 \
 658                 cmd;                                                    \
 659                 schedule();                                             \
 660                 spin_lock_irq(&lock);                                   \
 661         }                                                               \
 662         finish_wait(&wq, &__wait);                                      \
 663 } while (0)
 664
 665 /**
 666  * wait_event_lock_irq_cmd - sleep until a condition gets true. The
 667  *                           condition is checked under the lock. This
 668  *                           is expected to be called with the lock
 669  *                           taken.
 670  * @wq: the waitqueue to wait on
 671  * @condition: a C expression for the event to wait for
 672  * @lock: a locked spinlock_t, which will be released before cmd
 673  *        and schedule() and reacquired afterwards.
 674  * @cmd: a command which is invoked outside the critical section before
 675  *       sleep
 676  *
 677  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 678  * @condition evaluates to true. The @condition is checked each time
 679  * the waitqueue @wq is woken up.
 680  *
 681  * wake_up() has to be called after changing any variable that could
 682  * change the result of the wait condition.
 683  *
 684  * This is supposed to be called while holding the lock. The lock is
 685  * dropped before invoking the cmd and going to sleep and is reacquired
 686  * afterwards.
 687  */
 688 #define wait_event_lock_irq_cmd(wq, condition, lock, cmd)               \
 689 do {                                                                    \
 690         if (condition)                                                  \
 691                 break;                                                  \
 692         __wait_event_lock_irq(wq, condition, lock, cmd);                \
 693 } while (0)
 694
 695 /**
 696  * wait_event_lock_irq - sleep until a condition gets true. The
 697  *                       condition is checked under the lock. This
 698  *                       is expected to be called with the lock
 699  *                       taken.
 700  * @wq: the waitqueue to wait on
 701  * @condition: a C expression for the event to wait for
 702  * @lock: a locked spinlock_t, which will be released before schedule()
 703  *        and reacquired afterwards.
 704  *
 705  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 706  * @condition evaluates to true. The @condition is checked each time
 707  * the waitqueue @wq is woken up.
 708  *
 709  * wake_up() has to be called after changing any variable that could
 710  * change the result of the wait condition.
 711  *
 712  * This is supposed to be called while holding the lock. The lock is
 713  * dropped before going to sleep and is reacquired afterwards.
 714  */
 715 #define wait_event_lock_irq(wq, condition, lock)                        \
 716 do {                                                                    \
 717         if (condition)                                                  \
 718                 break;                                                  \
 719         __wait_event_lock_irq(wq, condition, lock, );                   \
 720 } while (0)
 721
 722
 723 #define __wait_event_interruptible_lock_irq(wq, condition,              \
 724                                             lock, ret, cmd)             \
 725 do {                                                                    \
 726         DEFINE_WAIT(__wait);                                            \
 727                                                                         \
 728         for (;;) {                                                      \
 729                 prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE);      \
 730                 if (condition)                                          \
 731                         break;                                          \
 732                 if (signal_pending(current)) {                          \
 733                         ret = -ERESTARTSYS;                             \
 734                         break;                                          \
 735                 }                                                       \
 736                 spin_unlock_irq(&lock);                                 \
 737                 cmd;                                                    \
 738                 schedule();                                             \
 739                 spin_lock_irq(&lock);                                   \
 740         }                                                               \
 741         finish_wait(&wq, &__wait);                                      \
 742 } while (0)
 743
 744 /**
 745  * wait_event_interruptible_lock_irq_cmd - sleep until a condition gets true.
 746  *              The condition is checked under the lock. This is expected to
 747  *              be called with the lock taken.
 748  * @wq: the waitqueue to wait on
 749  * @condition: a C expression for the event to wait for
 750  * @lock: a locked spinlock_t, which will be released before cmd and
 751  *        schedule() and reacquired afterwards.
 752  * @cmd: a command which is invoked outside the critical section before
 753  *       sleep
 754  *
 755  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 756  * @condition evaluates to true or a signal is received. The @condition is
 757  * checked each time the waitqueue @wq is woken up.
 758  *
 759  * wake_up() has to be called after changing any variable that could
 760  * change the result of the wait condition.
 761  *
 762  * This is supposed to be called while holding the lock. The lock is
 763  * dropped before invoking the cmd and going to sleep and is reacquired
 764  * afterwards.
 765  *
 766  * The macro will return -ERESTARTSYS if it was interrupted by a signal
 767  * and 0 if @condition evaluated to true.
 768  */
 769 #define wait_event_interruptible_lock_irq_cmd(wq, condition, lock, cmd) \
 770 ({                                                                      \
 771         int __ret = 0;                                                  \
 772                                                                         \
 773         if (!(condition))                                               \
 774                 __wait_event_interruptible_lock_irq(wq, condition,      \
 775                                                     lock, __ret, cmd);  \
 776         __ret;                                                          \
 777 })
 778
 779 /**
 780  * wait_event_interruptible_lock_irq - sleep until a condition gets true.
 781  *              The condition is checked under the lock. This is expected
 782  *              to be called with the lock taken.
 783  * @wq: the waitqueue to wait on
 784  * @condition: a C expression for the event to wait for
 785  * @lock: a locked spinlock_t, which will be released before schedule()
 786  *        and reacquired afterwards.
 787  *
 788  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 789  * @condition evaluates to true or signal is received. The @condition is
 790  * checked each time the waitqueue @wq is woken up.
 791  *
 792  * wake_up() has to be called after changing any variable that could
 793  * change the result of the wait condition.
 794  *
 795  * This is supposed to be called while holding the lock. The lock is
 796  * dropped before going to sleep and is reacquired afterwards.
 797  *
 798  * The macro will return -ERESTARTSYS if it was interrupted by a signal
 799  * and 0 if @condition evaluated to true.
 800  */
 801 #define wait_event_interruptible_lock_irq(wq, condition, lock)          \
 802 ({                                                                      \
 803         int __ret = 0;                                                  \
 804                                                                         \
 805         if (!(condition))                                               \
 806                 __wait_event_interruptible_lock_irq(wq, condition,      \
 807                                                     lock, __ret, );     \
 808         __ret;                                                          \
 809 })
 810
 811 #define __wait_event_interruptible_lock_irq_timeout(wq, condition,      \
 812                                                     lock, ret)          \
 813 do {                                                                    \
 814         DEFINE_WAIT(__wait);                                            \
 815                                                                         \
 816         for (;;) {                                                      \
 817                 prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE);      \
 818                 if (condition)                                          \
 819                         break;                                          \
 820                 if (signal_pending(current)) {                          \
 821                         ret = -ERESTARTSYS;                             \
 822                         break;                                          \
 823                 }                                                       \
 824                 spin_unlock_irq(&lock);                                 \
 825                 ret = schedule_timeout(ret);                            \
 826                 spin_lock_irq(&lock);                                   \
 827                 if (!ret)                                               \
 828                         break;                                          \
 829         }                                                               \
 830         finish_wait(&wq, &__wait);                                      \
 831 } while (0)
 832
 833 /**
 834  * wait_event_interruptible_lock_irq_timeout - sleep until a condition gets true or a timeout elapses.
 835  *              The condition is checked under the lock. This is expected
 836  *              to be called with the lock taken.
 837  * @wq: the waitqueue to wait on
 838  * @condition: a C expression for the event to wait for
 839  * @lock: a locked spinlock_t, which will be released before schedule()
 840  *        and reacquired afterwards.
 841  * @timeout: timeout, in jiffies
 842  *
 843  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 844  * @condition evaluates to true or signal is received. The @condition is
 845  * checked each time the waitqueue @wq is woken up.
 846  *
 847  * wake_up() has to be called after changing any variable that could
 848  * change the result of the wait condition.
 849  *
 850  * This is supposed to be called while holding the lock. The lock is
 851  * dropped before going to sleep and is reacquired afterwards.
 852  *
 853  * The function returns 0 if the @timeout elapsed, -ERESTARTSYS if it
 854  * was interrupted by a signal, and the remaining jiffies otherwise
 855  * if the condition evaluated to true before the timeout elapsed.
 856  */
 857 #define wait_event_interruptible_lock_irq_timeout(wq, condition, lock,  \
 858                                                   timeout)              \
 859 ({                                                                      \
 860         int __ret = timeout;                                            \
 861                                                                         \
 862         if (!(condition))                                               \
 863                 __wait_event_interruptible_lock_irq_timeout(            \
 864                                         wq, condition, lock, __ret);    \
 865         __ret;                                                          \
 866 })
 867
 868
 869 /*
 870  * These are the old interfaces to sleep waiting for an event.
 871  * They are racy.  DO NOT use them, use the wait_event* interfaces above.
 872  * We plan to remove these interfaces.
 873  */
 874 extern void sleep_on(wait_queue_head_t *q);
 875 extern long sleep_on_timeout(wait_queue_head_t *q,
 876                                       signed long timeout);
 877 extern void interruptible_sleep_on(wait_queue_head_t *q);
 878 extern long interruptible_sleep_on_timeout(wait_queue_head_t *q,
 879                                            signed long timeout);
 880
 881 /*
 882  * Waitqueues which are removed from the waitqueue_head at wakeup time
 883  */
 884 void prepare_to_wait(wait_queue_head_t *q, wait_queue_t *wait, int state);
 885 void prepare_to_wait_exclusive(wait_queue_head_t *q, wait_queue_t *wait, int state);
 886 void finish_wait(wait_queue_head_t *q, wait_queue_t *wait);
 887 void abort_exclusive_wait(wait_queue_head_t *q, wait_queue_t *wait,
 888                         unsigned int mode, void *key);
 889 int autoremove_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 890 int wake_bit_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 891
 892 #define DEFINE_WAIT_FUNC(name, function)                                \
 893         wait_queue_t name = {                                           \
 894                 .private        = current,                              \
 895                 .func           = function,                             \
 896                 .task_list      = LIST_HEAD_INIT((name).task_list),     \
 897         }
 898
 899 #define DEFINE_WAIT(name) DEFINE_WAIT_FUNC(name, autoremove_wake_function)
 900
 901 #define DEFINE_WAIT_BIT(name, word, bit)                                \
 902         struct wait_bit_queue name = {                                  \
 903                 .key = __WAIT_BIT_KEY_INITIALIZER(word, bit),           \
 904                 .wait   = {                                             \
 905                         .private        = current,                      \
 906                         .func           = wake_bit_function,            \
 907                         .task_list      =                               \
 908                                 LIST_HEAD_INIT((name).wait.task_list),  \
 909                 },                                                      \
 910         }
 911
 912 #define init_wait(wait)                                                 \
 913         do {                                                            \
 914                 (wait)->private = current;                              \
 915                 (wait)->func = autoremove_wake_function;                \
 916                 INIT_LIST_HEAD(&(wait)->task_list);                     \
 917                 (wait)->flags = 0;                                      \
 918         } while (0)
 919
 920 /**
 921  * wait_on_bit - wait for a bit to be cleared
 922  * @word: the word being waited on, a kernel virtual address
 923  * @bit: the bit of the word being waited on
 924  * @action: the function used to sleep, which may take special actions
 925  * @mode: the task state to sleep in
 926  *
 927  * There is a standard hashed waitqueue table for generic use. This
 928  * is the part of the hashtable's accessor API that waits on a bit.
 929  * For instance, if one were to have waiters on a bitflag, one would
 930  * call wait_on_bit() in threads waiting for the bit to clear.
 931  * One uses wait_on_bit() where one is waiting for the bit to clear,
 932  * but has no intention of setting it.
 933  */
 934 static inline int wait_on_bit(void *word, int bit,
 935                                 int (*action)(void *), unsigned mode)
 936 {
 937         if (!test_bit(bit, word))
 938                 return 0;
 939         return out_of_line_wait_on_bit(word, bit, action, mode);
 940 }
 941
 942 /**
 943  * wait_on_bit_lock - wait for a bit to be cleared, when wanting to set it
 944  * @word: the word being waited on, a kernel virtual address
 945  * @bit: the bit of the word being waited on
 946  * @action: the function used to sleep, which may take special actions
 947  * @mode: the task state to sleep in
 948  *
 949  * There is a standard hashed waitqueue table for generic use. This
 950  * is the part of the hashtable's accessor API that waits on a bit
 951  * when one intends to set it, for instance, trying to lock bitflags.
 952  * For instance, if one were to have waiters trying to set bitflag
 953  * and waiting for it to clear before setting it, one would call
 954  * wait_on_bit() in threads waiting to be able to set the bit.
 955  * One uses wait_on_bit_lock() where one is waiting for the bit to
 956  * clear with the intention of setting it, and when done, clearing it.
 957  */
 958 static inline int wait_on_bit_lock(void *word, int bit,
 959                                 int (*action)(void *), unsigned mode)
 960 {
 961         if (!test_and_set_bit(bit, word))
 962                 return 0;
 963         return out_of_line_wait_on_bit_lock(word, bit, action, mode);
 964 }
 965
 966 /**
 967  * wait_on_atomic_t - Wait for an atomic_t to become 0
 968  * @val: The atomic value being waited on, a kernel virtual address
 969  * @action: the function used to sleep, which may take special actions
 970  * @mode: the task state to sleep in
 971  *
 972  * Wait for an atomic_t to become 0.  We abuse the bit-wait waitqueue table for
 973  * the purpose of getting a waitqueue, but we set the key to a bit number
 974  * outside of the target 'word'.
 975  */
 976 static inline
 977 int wait_on_atomic_t(atomic_t *val, int (*action)(atomic_t *), unsigned mode)
 978 {
 979         if (atomic_read(val) == 0)
 980                 return 0;
 981         return out_of_line_wait_on_atomic_t(val, action, mode);
 982 }
 983
 984 #endif