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_cond_timeout(condition, ret)                            \
 183 ({                                                                      \
 184         bool __cond = (condition);                                      \
 185         if (__cond && !ret)                                             \
 186                 ret = 1;                                                \
 187         __cond || !ret;                                                 \
 188 })
 189
 190 #define ___wait_signal_pending(state)                                   \
 191         ((state == TASK_INTERRUPTIBLE && signal_pending(current)) ||    \
 192          (state == TASK_KILLABLE && fatal_signal_pending(current)))
 193
 194 #define ___wait_nop_ret         int ret __always_unused
 195
 196 #define ___wait_event(wq, condition, state, exclusive, ret, cmd)        \
 197 do {                                                                    \
 198         __label__ __out;                                                \
 199         DEFINE_WAIT(__wait);                                            \
 200                                                                         \
 201         for (;;) {                                                      \
 202                 if (exclusive)                                          \
 203                         prepare_to_wait_exclusive(&wq, &__wait, state); \
 204                 else                                                    \
 205                         prepare_to_wait(&wq, &__wait, state);           \
 206                                                                         \
 207                 if (condition)                                          \
 208                         break;                                          \
 209                                                                         \
 210                 if (___wait_signal_pending(state)) {                    \
 211                         ret = -ERESTARTSYS;                             \
 212                         if (exclusive) {                                \
 213                                 abort_exclusive_wait(&wq, &__wait,      \
 214                                                      state, NULL);      \
 215                                 goto __out;                             \
 216                         }                                               \
 217                         break;                                          \
 218                 }                                                       \
 219                                                                         \
 220                 cmd;                                                    \
 221         }                                                               \
 222         finish_wait(&wq, &__wait);                                      \
 223 __out:  ;                                                               \
 224 } while (0)
 225
 226 #define __wait_event(wq, condition)                                     \
 227         ___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0,           \
 228                       ___wait_nop_ret, schedule())
 229
 230 /**
 231  * wait_event - sleep until a condition gets true
 232  * @wq: the waitqueue to wait on
 233  * @condition: a C expression for the event to wait for
 234  *
 235  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 236  * @condition evaluates to true. The @condition is checked each time
 237  * the waitqueue @wq is woken up.
 238  *
 239  * wake_up() has to be called after changing any variable that could
 240  * change the result of the wait condition.
 241  */
 242 #define wait_event(wq, condition)                                       \
 243 do {                                                                    \
 244         if (condition)                                                  \
 245                 break;                                                  \
 246         __wait_event(wq, condition);                                    \
 247 } while (0)
 248
 249 #define __wait_event_timeout(wq, condition, ret)                        \
 250         ___wait_event(wq, ___wait_cond_timeout(condition, ret),         \
 251                       TASK_UNINTERRUPTIBLE, 0, ret,                     \
 252                       ret = schedule_timeout(ret))
 253
 254 /**
 255  * wait_event_timeout - sleep until a condition gets true or a timeout elapses
 256  * @wq: the waitqueue to wait on
 257  * @condition: a C expression for the event to wait for
 258  * @timeout: timeout, in jiffies
 259  *
 260  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 261  * @condition evaluates to true. The @condition is checked each time
 262  * the waitqueue @wq is woken up.
 263  *
 264  * wake_up() has to be called after changing any variable that could
 265  * change the result of the wait condition.
 266  *
 267  * The function returns 0 if the @timeout elapsed, or the remaining
 268  * jiffies (at least 1) if the @condition evaluated to %true before
 269  * the @timeout elapsed.
 270  */
 271 #define wait_event_timeout(wq, condition, timeout)                      \
 272 ({                                                                      \
 273         long __ret = timeout;                                           \
 274         if (!(condition))                                               \
 275                 __wait_event_timeout(wq, condition, __ret);             \
 276         __ret;                                                          \
 277 })
 278
 279 #define __wait_event_interruptible(wq, condition, ret)                  \
 280 do {                                                                    \
 281         DEFINE_WAIT(__wait);                                            \
 282                                                                         \
 283         for (;;) {                                                      \
 284                 prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE);      \
 285                 if (condition)                                          \
 286                         break;                                          \
 287                 if (signal_pending(current)) {                          \
 288                         ret = -ERESTARTSYS;                             \
 289                         break;                                          \
 290                 }                                                       \
 291                 schedule();                                             \
 292         }                                                               \
 293         finish_wait(&wq, &__wait);                                      \
 294 } while (0)
 295
 296 /**
 297  * wait_event_interruptible - sleep until a condition gets true
 298  * @wq: the waitqueue to wait on
 299  * @condition: a C expression for the event to wait for
 300  *
 301  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 302  * @condition evaluates to true or a signal is received.
 303  * The @condition is checked each time the waitqueue @wq is woken up.
 304  *
 305  * wake_up() has to be called after changing any variable that could
 306  * change the result of the wait condition.
 307  *
 308  * The function will return -ERESTARTSYS if it was interrupted by a
 309  * signal and 0 if @condition evaluated to true.
 310  */
 311 #define wait_event_interruptible(wq, condition)                         \
 312 ({                                                                      \
 313         int __ret = 0;                                                  \
 314         if (!(condition))                                               \
 315                 __wait_event_interruptible(wq, condition, __ret);       \
 316         __ret;                                                          \
 317 })
 318
 319 #define __wait_event_interruptible_timeout(wq, condition, ret)          \
 320 do {                                                                    \
 321         DEFINE_WAIT(__wait);                                            \
 322                                                                         \
 323         for (;;) {                                                      \
 324                 prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE);      \
 325                 if (___wait_cond_timeout(condition, ret))               \
 326                         break;                                          \
 327                 if (signal_pending(current)) {                          \
 328                         ret = -ERESTARTSYS;                             \
 329                         break;                                          \
 330                 }                                                       \
 331                 ret = schedule_timeout(ret);                            \
 332         }                                                               \
 333         finish_wait(&wq, &__wait);                                      \
 334 } while (0)
 335
 336 /**
 337  * wait_event_interruptible_timeout - sleep until a condition gets true or a timeout elapses
 338  * @wq: the waitqueue to wait on
 339  * @condition: a C expression for the event to wait for
 340  * @timeout: timeout, in jiffies
 341  *
 342  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 343  * @condition evaluates to true or a signal is received.
 344  * The @condition is checked each time the waitqueue @wq is woken up.
 345  *
 346  * wake_up() has to be called after changing any variable that could
 347  * change the result of the wait condition.
 348  *
 349  * Returns:
 350  * 0 if the @timeout elapsed, -%ERESTARTSYS if it was interrupted by
 351  * a signal, or the remaining jiffies (at least 1) if the @condition
 352  * evaluated to %true before the @timeout elapsed.
 353  */
 354 #define wait_event_interruptible_timeout(wq, condition, timeout)        \
 355 ({                                                                      \
 356         long __ret = timeout;                                           \
 357         if (!(condition))                                               \
 358                 __wait_event_interruptible_timeout(wq, condition, __ret); \
 359         __ret;                                                          \
 360 })
 361
 362 #define __wait_event_hrtimeout(wq, condition, timeout, state)           \
 363 ({                                                                      \
 364         int __ret = 0;                                                  \
 365         DEFINE_WAIT(__wait);                                            \
 366         struct hrtimer_sleeper __t;                                     \
 367                                                                         \
 368         hrtimer_init_on_stack(&__t.timer, CLOCK_MONOTONIC,              \
 369                               HRTIMER_MODE_REL);                        \
 370         hrtimer_init_sleeper(&__t, current);                            \
 371         if ((timeout).tv64 != KTIME_MAX)                                \
 372                 hrtimer_start_range_ns(&__t.timer, timeout,             \
 373                                        current->timer_slack_ns,         \
 374                                        HRTIMER_MODE_REL);               \
 375                                                                         \
 376         for (;;) {                                                      \
 377                 prepare_to_wait(&wq, &__wait, state);                   \
 378                 if (condition)                                          \
 379                         break;                                          \
 380                 if (state == TASK_INTERRUPTIBLE &&                      \
 381                     signal_pending(current)) {                          \
 382                         __ret = -ERESTARTSYS;                           \
 383                         break;                                          \
 384                 }                                                       \
 385                 if (!__t.task) {                                        \
 386                         __ret = -ETIME;                                 \
 387                         break;                                          \
 388                 }                                                       \
 389                 schedule();                                             \
 390         }                                                               \
 391                                                                         \
 392         hrtimer_cancel(&__t.timer);                                     \
 393         destroy_hrtimer_on_stack(&__t.timer);                           \
 394         finish_wait(&wq, &__wait);                                      \
 395         __ret;                                                          \
 396 })
 397
 398 /**
 399  * wait_event_hrtimeout - sleep until a condition gets true or a timeout elapses
 400  * @wq: the waitqueue to wait on
 401  * @condition: a C expression for the event to wait for
 402  * @timeout: timeout, as a ktime_t
 403  *
 404  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 405  * @condition evaluates to true or a signal is received.
 406  * The @condition is checked each time the waitqueue @wq is woken up.
 407  *
 408  * wake_up() has to be called after changing any variable that could
 409  * change the result of the wait condition.
 410  *
 411  * The function returns 0 if @condition became true, or -ETIME if the timeout
 412  * elapsed.
 413  */
 414 #define wait_event_hrtimeout(wq, condition, timeout)                    \
 415 ({                                                                      \
 416         int __ret = 0;                                                  \
 417         if (!(condition))                                               \
 418                 __ret = __wait_event_hrtimeout(wq, condition, timeout,  \
 419                                                TASK_UNINTERRUPTIBLE);   \
 420         __ret;                                                          \
 421 })
 422
 423 /**
 424  * wait_event_interruptible_hrtimeout - sleep until a condition gets true or a timeout elapses
 425  * @wq: the waitqueue to wait on
 426  * @condition: a C expression for the event to wait for
 427  * @timeout: timeout, as a ktime_t
 428  *
 429  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 430  * @condition evaluates to true or a signal is received.
 431  * The @condition is checked each time the waitqueue @wq is woken up.
 432  *
 433  * wake_up() has to be called after changing any variable that could
 434  * change the result of the wait condition.
 435  *
 436  * The function returns 0 if @condition became true, -ERESTARTSYS if it was
 437  * interrupted by a signal, or -ETIME if the timeout elapsed.
 438  */
 439 #define wait_event_interruptible_hrtimeout(wq, condition, timeout)      \
 440 ({                                                                      \
 441         long __ret = 0;                                                 \
 442         if (!(condition))                                               \
 443                 __ret = __wait_event_hrtimeout(wq, condition, timeout,  \
 444                                                TASK_INTERRUPTIBLE);     \
 445         __ret;                                                          \
 446 })
 447
 448 #define __wait_event_interruptible_exclusive(wq, condition, ret)        \
 449 do {                                                                    \
 450         __label__ __out;                                                \
 451         DEFINE_WAIT(__wait);                                            \
 452                                                                         \
 453         for (;;) {                                                      \
 454                 prepare_to_wait_exclusive(&wq, &__wait,                 \
 455                                         TASK_INTERRUPTIBLE);            \
 456                 if (condition)                                          \
 457                         break;                                          \
 458                 if (signal_pending(current)) {                          \
 459                         ret = -ERESTARTSYS;                             \
 460                         abort_exclusive_wait(&wq, &__wait,              \
 461                                 TASK_INTERRUPTIBLE, NULL);              \
 462                         goto __out;                                     \
 463                 }                                                       \
 464                 schedule();                                             \
 465         }                                                               \
 466         finish_wait(&wq, &__wait);                                      \
 467 __out:  ;                                                               \
 468 } while (0)
 469
 470 #define wait_event_interruptible_exclusive(wq, condition)               \
 471 ({                                                                      \
 472         int __ret = 0;                                                  \
 473         if (!(condition))                                               \
 474                 __wait_event_interruptible_exclusive(wq, condition, __ret);\
 475         __ret;                                                          \
 476 })
 477
 478
 479 #define __wait_event_interruptible_locked(wq, condition, exclusive, irq) \
 480 ({                                                                      \
 481         int __ret = 0;                                                  \
 482         DEFINE_WAIT(__wait);                                            \
 483         if (exclusive)                                                  \
 484                 __wait.flags |= WQ_FLAG_EXCLUSIVE;                      \
 485         do {                                                            \
 486                 if (likely(list_empty(&__wait.task_list)))              \
 487                         __add_wait_queue_tail(&(wq), &__wait);          \
 488                 set_current_state(TASK_INTERRUPTIBLE);                  \
 489                 if (signal_pending(current)) {                          \
 490                         __ret = -ERESTARTSYS;                           \
 491                         break;                                          \
 492                 }                                                       \
 493                 if (irq)                                                \
 494                         spin_unlock_irq(&(wq).lock);                    \
 495                 else                                                    \
 496                         spin_unlock(&(wq).lock);                        \
 497                 schedule();                                             \
 498                 if (irq)                                                \
 499                         spin_lock_irq(&(wq).lock);                      \
 500                 else                                                    \
 501                         spin_lock(&(wq).lock);                          \
 502         } while (!(condition));                                         \
 503         __remove_wait_queue(&(wq), &__wait);                            \
 504         __set_current_state(TASK_RUNNING);                              \
 505         __ret;                                                          \
 506 })
 507
 508
 509 /**
 510  * wait_event_interruptible_locked - sleep until a condition gets true
 511  * @wq: the waitqueue to wait on
 512  * @condition: a C expression for the event to wait for
 513  *
 514  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 515  * @condition evaluates to true or a signal is received.
 516  * The @condition is checked each time the waitqueue @wq is woken up.
 517  *
 518  * It must be called with wq.lock being held.  This spinlock is
 519  * unlocked while sleeping but @condition testing is done while lock
 520  * is held and when this macro exits the lock is held.
 521  *
 522  * The lock is locked/unlocked using spin_lock()/spin_unlock()
 523  * functions which must match the way they are locked/unlocked outside
 524  * of this macro.
 525  *
 526  * wake_up_locked() has to be called after changing any variable that could
 527  * change the result of the wait condition.
 528  *
 529  * The function will return -ERESTARTSYS if it was interrupted by a
 530  * signal and 0 if @condition evaluated to true.
 531  */
 532 #define wait_event_interruptible_locked(wq, condition)                  \
 533         ((condition)                                                    \
 534          ? 0 : __wait_event_interruptible_locked(wq, condition, 0, 0))
 535
 536 /**
 537  * wait_event_interruptible_locked_irq - sleep until a condition gets true
 538  * @wq: the waitqueue to wait on
 539  * @condition: a C expression for the event to wait for
 540  *
 541  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 542  * @condition evaluates to true or a signal is received.
 543  * The @condition is checked each time the waitqueue @wq is woken up.
 544  *
 545  * It must be called with wq.lock being held.  This spinlock is
 546  * unlocked while sleeping but @condition testing is done while lock
 547  * is held and when this macro exits the lock is held.
 548  *
 549  * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq()
 550  * functions which must match the way they are locked/unlocked outside
 551  * of this macro.
 552  *
 553  * wake_up_locked() has to be called after changing any variable that could
 554  * change the result of the wait condition.
 555  *
 556  * The function will return -ERESTARTSYS if it was interrupted by a
 557  * signal and 0 if @condition evaluated to true.
 558  */
 559 #define wait_event_interruptible_locked_irq(wq, condition)              \
 560         ((condition)                                                    \
 561          ? 0 : __wait_event_interruptible_locked(wq, condition, 0, 1))
 562
 563 /**
 564  * wait_event_interruptible_exclusive_locked - sleep exclusively until a condition gets true
 565  * @wq: the waitqueue to wait on
 566  * @condition: a C expression for the event to wait for
 567  *
 568  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 569  * @condition evaluates to true or a signal is received.
 570  * The @condition is checked each time the waitqueue @wq is woken up.
 571  *
 572  * It must be called with wq.lock being held.  This spinlock is
 573  * unlocked while sleeping but @condition testing is done while lock
 574  * is held and when this macro exits the lock is held.
 575  *
 576  * The lock is locked/unlocked using spin_lock()/spin_unlock()
 577  * functions which must match the way they are locked/unlocked outside
 578  * of this macro.
 579  *
 580  * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
 581  * set thus when other process waits process on the list if this
 582  * process is awaken further processes are not considered.
 583  *
 584  * wake_up_locked() has to be called after changing any variable that could
 585  * change the result of the wait condition.
 586  *
 587  * The function will return -ERESTARTSYS if it was interrupted by a
 588  * signal and 0 if @condition evaluated to true.
 589  */
 590 #define wait_event_interruptible_exclusive_locked(wq, condition)        \
 591         ((condition)                                                    \
 592          ? 0 : __wait_event_interruptible_locked(wq, condition, 1, 0))
 593
 594 /**
 595  * wait_event_interruptible_exclusive_locked_irq - sleep until a condition gets true
 596  * @wq: the waitqueue to wait on
 597  * @condition: a C expression for the event to wait for
 598  *
 599  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 600  * @condition evaluates to true or a signal is received.
 601  * The @condition is checked each time the waitqueue @wq is woken up.
 602  *
 603  * It must be called with wq.lock being held.  This spinlock is
 604  * unlocked while sleeping but @condition testing is done while lock
 605  * is held and when this macro exits the lock is held.
 606  *
 607  * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq()
 608  * functions which must match the way they are locked/unlocked outside
 609  * of this macro.
 610  *
 611  * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
 612  * set thus when other process waits process on the list if this
 613  * process is awaken further processes are not considered.
 614  *
 615  * wake_up_locked() has to be called after changing any variable that could
 616  * change the result of the wait condition.
 617  *
 618  * The function will return -ERESTARTSYS if it was interrupted by a
 619  * signal and 0 if @condition evaluated to true.
 620  */
 621 #define wait_event_interruptible_exclusive_locked_irq(wq, condition)    \
 622         ((condition)                                                    \
 623          ? 0 : __wait_event_interruptible_locked(wq, condition, 1, 1))
 624
 625
 626
 627 #define __wait_event_killable(wq, condition, ret)                       \
 628 do {                                                                    \
 629         DEFINE_WAIT(__wait);                                            \
 630                                                                         \
 631         for (;;) {                                                      \
 632                 prepare_to_wait(&wq, &__wait, TASK_KILLABLE);           \
 633                 if (condition)                                          \
 634                         break;                                          \
 635                 if (!fatal_signal_pending(current)) {                   \
 636                         schedule();                                     \
 637                         continue;                                       \
 638                 }                                                       \
 639                 ret = -ERESTARTSYS;                                     \
 640                 break;                                                  \
 641         }                                                               \
 642         finish_wait(&wq, &__wait);                                      \
 643 } while (0)
 644
 645 /**
 646  * wait_event_killable - sleep until a condition gets true
 647  * @wq: the waitqueue to wait on
 648  * @condition: a C expression for the event to wait for
 649  *
 650  * The process is put to sleep (TASK_KILLABLE) until the
 651  * @condition evaluates to true or a signal is received.
 652  * The @condition is checked each time the waitqueue @wq is woken up.
 653  *
 654  * wake_up() has to be called after changing any variable that could
 655  * change the result of the wait condition.
 656  *
 657  * The function will return -ERESTARTSYS if it was interrupted by a
 658  * signal and 0 if @condition evaluated to true.
 659  */
 660 #define wait_event_killable(wq, condition)                              \
 661 ({                                                                      \
 662         int __ret = 0;                                                  \
 663         if (!(condition))                                               \
 664                 __wait_event_killable(wq, condition, __ret);            \
 665         __ret;                                                          \
 666 })
 667
 668
 669 #define __wait_event_lock_irq(wq, condition, lock, cmd)                 \
 670 do {                                                                    \
 671         DEFINE_WAIT(__wait);                                            \
 672                                                                         \
 673         for (;;) {                                                      \
 674                 prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE);    \
 675                 if (condition)                                          \
 676                         break;                                          \
 677                 spin_unlock_irq(&lock);                                 \
 678                 cmd;                                                    \
 679                 schedule();                                             \
 680                 spin_lock_irq(&lock);                                   \
 681         }                                                               \
 682         finish_wait(&wq, &__wait);                                      \
 683 } while (0)
 684
 685 /**
 686  * wait_event_lock_irq_cmd - sleep until a condition gets true. The
 687  *                           condition is checked under the lock. This
 688  *                           is expected to be called with the lock
 689  *                           taken.
 690  * @wq: the waitqueue to wait on
 691  * @condition: a C expression for the event to wait for
 692  * @lock: a locked spinlock_t, which will be released before cmd
 693  *        and schedule() and reacquired afterwards.
 694  * @cmd: a command which is invoked outside the critical section before
 695  *       sleep
 696  *
 697  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 698  * @condition evaluates to true. The @condition is checked each time
 699  * the waitqueue @wq is woken up.
 700  *
 701  * wake_up() has to be called after changing any variable that could
 702  * change the result of the wait condition.
 703  *
 704  * This is supposed to be called while holding the lock. The lock is
 705  * dropped before invoking the cmd and going to sleep and is reacquired
 706  * afterwards.
 707  */
 708 #define wait_event_lock_irq_cmd(wq, condition, lock, cmd)               \
 709 do {                                                                    \
 710         if (condition)                                                  \
 711                 break;                                                  \
 712         __wait_event_lock_irq(wq, condition, lock, cmd);                \
 713 } while (0)
 714
 715 /**
 716  * wait_event_lock_irq - sleep until a condition gets true. The
 717  *                       condition is checked under the lock. This
 718  *                       is expected to be called with the lock
 719  *                       taken.
 720  * @wq: the waitqueue to wait on
 721  * @condition: a C expression for the event to wait for
 722  * @lock: a locked spinlock_t, which will be released before schedule()
 723  *        and reacquired afterwards.
 724  *
 725  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 726  * @condition evaluates to true. The @condition is checked each time
 727  * the waitqueue @wq is woken up.
 728  *
 729  * wake_up() has to be called after changing any variable that could
 730  * change the result of the wait condition.
 731  *
 732  * This is supposed to be called while holding the lock. The lock is
 733  * dropped before going to sleep and is reacquired afterwards.
 734  */
 735 #define wait_event_lock_irq(wq, condition, lock)                        \
 736 do {                                                                    \
 737         if (condition)                                                  \
 738                 break;                                                  \
 739         __wait_event_lock_irq(wq, condition, lock, );                   \
 740 } while (0)
 741
 742
 743 #define __wait_event_interruptible_lock_irq(wq, condition,              \
 744                                             lock, ret, cmd)             \
 745 do {                                                                    \
 746         DEFINE_WAIT(__wait);                                            \
 747                                                                         \
 748         for (;;) {                                                      \
 749                 prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE);      \
 750                 if (condition)                                          \
 751                         break;                                          \
 752                 if (signal_pending(current)) {                          \
 753                         ret = -ERESTARTSYS;                             \
 754                         break;                                          \
 755                 }                                                       \
 756                 spin_unlock_irq(&lock);                                 \
 757                 cmd;                                                    \
 758                 schedule();                                             \
 759                 spin_lock_irq(&lock);                                   \
 760         }                                                               \
 761         finish_wait(&wq, &__wait);                                      \
 762 } while (0)
 763
 764 /**
 765  * wait_event_interruptible_lock_irq_cmd - sleep until a condition gets true.
 766  *              The condition is checked under the lock. This is expected to
 767  *              be called with the lock taken.
 768  * @wq: the waitqueue to wait on
 769  * @condition: a C expression for the event to wait for
 770  * @lock: a locked spinlock_t, which will be released before cmd and
 771  *        schedule() and reacquired afterwards.
 772  * @cmd: a command which is invoked outside the critical section before
 773  *       sleep
 774  *
 775  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 776  * @condition evaluates to true or a signal is received. The @condition is
 777  * checked each time the waitqueue @wq is woken up.
 778  *
 779  * wake_up() has to be called after changing any variable that could
 780  * change the result of the wait condition.
 781  *
 782  * This is supposed to be called while holding the lock. The lock is
 783  * dropped before invoking the cmd and going to sleep and is reacquired
 784  * afterwards.
 785  *
 786  * The macro will return -ERESTARTSYS if it was interrupted by a signal
 787  * and 0 if @condition evaluated to true.
 788  */
 789 #define wait_event_interruptible_lock_irq_cmd(wq, condition, lock, cmd) \
 790 ({                                                                      \
 791         int __ret = 0;                                                  \
 792                                                                         \
 793         if (!(condition))                                               \
 794                 __wait_event_interruptible_lock_irq(wq, condition,      \
 795                                                     lock, __ret, cmd);  \
 796         __ret;                                                          \
 797 })
 798
 799 /**
 800  * wait_event_interruptible_lock_irq - sleep until a condition gets true.
 801  *              The condition is checked under the lock. This is expected
 802  *              to be called with the lock taken.
 803  * @wq: the waitqueue to wait on
 804  * @condition: a C expression for the event to wait for
 805  * @lock: a locked spinlock_t, which will be released before schedule()
 806  *        and reacquired afterwards.
 807  *
 808  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 809  * @condition evaluates to true or signal is received. The @condition is
 810  * checked each time the waitqueue @wq is woken up.
 811  *
 812  * wake_up() has to be called after changing any variable that could
 813  * change the result of the wait condition.
 814  *
 815  * This is supposed to be called while holding the lock. The lock is
 816  * dropped before going to sleep and is reacquired afterwards.
 817  *
 818  * The macro will return -ERESTARTSYS if it was interrupted by a signal
 819  * and 0 if @condition evaluated to true.
 820  */
 821 #define wait_event_interruptible_lock_irq(wq, condition, lock)          \
 822 ({                                                                      \
 823         int __ret = 0;                                                  \
 824                                                                         \
 825         if (!(condition))                                               \
 826                 __wait_event_interruptible_lock_irq(wq, condition,      \
 827                                                     lock, __ret, );     \
 828         __ret;                                                          \
 829 })
 830
 831 #define __wait_event_interruptible_lock_irq_timeout(wq, condition,      \
 832                                                     lock, ret)          \
 833 do {                                                                    \
 834         DEFINE_WAIT(__wait);                                            \
 835                                                                         \
 836         for (;;) {                                                      \
 837                 prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE);      \
 838                 if (___wait_cond_timeout(condition, ret))               \
 839                         break;                                          \
 840                 if (signal_pending(current)) {                          \
 841                         ret = -ERESTARTSYS;                             \
 842                         break;                                          \
 843                 }                                                       \
 844                 spin_unlock_irq(&lock);                                 \
 845                 ret = schedule_timeout(ret);                            \
 846                 spin_lock_irq(&lock);                                   \
 847         }                                                               \
 848         finish_wait(&wq, &__wait);                                      \
 849 } while (0)
 850
 851 /**
 852  * wait_event_interruptible_lock_irq_timeout - sleep until a condition gets true or a timeout elapses.
 853  *              The condition is checked under the lock. This is expected
 854  *              to be called with the lock taken.
 855  * @wq: the waitqueue to wait on
 856  * @condition: a C expression for the event to wait for
 857  * @lock: a locked spinlock_t, which will be released before schedule()
 858  *        and reacquired afterwards.
 859  * @timeout: timeout, in jiffies
 860  *
 861  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 862  * @condition evaluates to true or signal is received. The @condition is
 863  * checked each time the waitqueue @wq is woken up.
 864  *
 865  * wake_up() has to be called after changing any variable that could
 866  * change the result of the wait condition.
 867  *
 868  * This is supposed to be called while holding the lock. The lock is
 869  * dropped before going to sleep and is reacquired afterwards.
 870  *
 871  * The function returns 0 if the @timeout elapsed, -ERESTARTSYS if it
 872  * was interrupted by a signal, and the remaining jiffies otherwise
 873  * if the condition evaluated to true before the timeout elapsed.
 874  */
 875 #define wait_event_interruptible_lock_irq_timeout(wq, condition, lock,  \
 876                                                   timeout)              \
 877 ({                                                                      \
 878         int __ret = timeout;                                            \
 879                                                                         \
 880         if (!(condition))                                               \
 881                 __wait_event_interruptible_lock_irq_timeout(            \
 882                                         wq, condition, lock, __ret);    \
 883         __ret;                                                          \
 884 })
 885
 886
 887 /*
 888  * These are the old interfaces to sleep waiting for an event.
 889  * They are racy.  DO NOT use them, use the wait_event* interfaces above.
 890  * We plan to remove these interfaces.
 891  */
 892 extern void sleep_on(wait_queue_head_t *q);
 893 extern long sleep_on_timeout(wait_queue_head_t *q,
 894                                       signed long timeout);
 895 extern void interruptible_sleep_on(wait_queue_head_t *q);
 896 extern long interruptible_sleep_on_timeout(wait_queue_head_t *q,
 897                                            signed long timeout);
 898
 899 /*
 900  * Waitqueues which are removed from the waitqueue_head at wakeup time
 901  */
 902 void prepare_to_wait(wait_queue_head_t *q, wait_queue_t *wait, int state);
 903 void prepare_to_wait_exclusive(wait_queue_head_t *q, wait_queue_t *wait, int state);
 904 void finish_wait(wait_queue_head_t *q, wait_queue_t *wait);
 905 void abort_exclusive_wait(wait_queue_head_t *q, wait_queue_t *wait,
 906                         unsigned int mode, void *key);
 907 int autoremove_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 908 int wake_bit_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 909
 910 #define DEFINE_WAIT_FUNC(name, function)                                \
 911         wait_queue_t name = {                                           \
 912                 .private        = current,                              \
 913                 .func           = function,                             \
 914                 .task_list      = LIST_HEAD_INIT((name).task_list),     \
 915         }
 916
 917 #define DEFINE_WAIT(name) DEFINE_WAIT_FUNC(name, autoremove_wake_function)
 918
 919 #define DEFINE_WAIT_BIT(name, word, bit)                                \
 920         struct wait_bit_queue name = {                                  \
 921                 .key = __WAIT_BIT_KEY_INITIALIZER(word, bit),           \
 922                 .wait   = {                                             \
 923                         .private        = current,                      \
 924                         .func           = wake_bit_function,            \
 925                         .task_list      =                               \
 926                                 LIST_HEAD_INIT((name).wait.task_list),  \
 927                 },                                                      \
 928         }
 929
 930 #define init_wait(wait)                                                 \
 931         do {                                                            \
 932                 (wait)->private = current;                              \
 933                 (wait)->func = autoremove_wake_function;                \
 934                 INIT_LIST_HEAD(&(wait)->task_list);                     \
 935                 (wait)->flags = 0;                                      \
 936         } while (0)
 937
 938 /**
 939  * wait_on_bit - wait for a bit to be cleared
 940  * @word: the word being waited on, a kernel virtual address
 941  * @bit: the bit of the word being waited on
 942  * @action: the function used to sleep, which may take special actions
 943  * @mode: the task state to sleep in
 944  *
 945  * There is a standard hashed waitqueue table for generic use. This
 946  * is the part of the hashtable's accessor API that waits on a bit.
 947  * For instance, if one were to have waiters on a bitflag, one would
 948  * call wait_on_bit() in threads waiting for the bit to clear.
 949  * One uses wait_on_bit() where one is waiting for the bit to clear,
 950  * but has no intention of setting it.
 951  */
 952 static inline int wait_on_bit(void *word, int bit,
 953                                 int (*action)(void *), unsigned mode)
 954 {
 955         if (!test_bit(bit, word))
 956                 return 0;
 957         return out_of_line_wait_on_bit(word, bit, action, mode);
 958 }
 959
 960 /**
 961  * wait_on_bit_lock - wait for a bit to be cleared, when wanting to set it
 962  * @word: the word being waited on, a kernel virtual address
 963  * @bit: the bit of the word being waited on
 964  * @action: the function used to sleep, which may take special actions
 965  * @mode: the task state to sleep in
 966  *
 967  * There is a standard hashed waitqueue table for generic use. This
 968  * is the part of the hashtable's accessor API that waits on a bit
 969  * when one intends to set it, for instance, trying to lock bitflags.
 970  * For instance, if one were to have waiters trying to set bitflag
 971  * and waiting for it to clear before setting it, one would call
 972  * wait_on_bit() in threads waiting to be able to set the bit.
 973  * One uses wait_on_bit_lock() where one is waiting for the bit to
 974  * clear with the intention of setting it, and when done, clearing it.
 975  */
 976 static inline int wait_on_bit_lock(void *word, int bit,
 977                                 int (*action)(void *), unsigned mode)
 978 {
 979         if (!test_and_set_bit(bit, word))
 980                 return 0;
 981         return out_of_line_wait_on_bit_lock(word, bit, action, mode);
 982 }
 983
 984 /**
 985  * wait_on_atomic_t - Wait for an atomic_t to become 0
 986  * @val: The atomic value being waited on, a kernel virtual address
 987  * @action: the function used to sleep, which may take special actions
 988  * @mode: the task state to sleep in
 989  *
 990  * Wait for an atomic_t to become 0.  We abuse the bit-wait waitqueue table for
 991  * the purpose of getting a waitqueue, but we set the key to a bit number
 992  * outside of the target 'word'.
 993  */
 994 static inline
 995 int wait_on_atomic_t(atomic_t *val, int (*action)(atomic_t *), unsigned mode)
 996 {
 997         if (atomic_read(val) == 0)
 998                 return 0;
 999         return out_of_line_wait_on_atomic_t(val, action, mode);
1000 }
1001
1002 #endif