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