include/linux/wait.h

   1 #ifndef _LINUX_WAIT_H
   2 #define _LINUX_WAIT_H
   3 /*
   4  * Linux wait queue related types and methods
   5  */
   6 #include <linux/list.h>
   7 #include <linux/stddef.h>
   8 #include <linux/spinlock.h>
   9 #include <asm/current.h>
  10 #include <uapi/linux/wait.h>
  11
  12 typedef struct __wait_queue wait_queue_t;
  13 typedef int (*wait_queue_func_t)(wait_queue_t *wait, unsigned mode, int flags, void *key);
  14 int default_wake_function(wait_queue_t *wait, unsigned mode, int flags, void *key);
  15
  16 struct __wait_queue {
  17         unsigned int            flags;
  18 #define WQ_FLAG_EXCLUSIVE       0x01
  19         void                    *private;
  20         wait_queue_func_t       func;
  21         struct list_head        task_list;
  22 };
  23
  24 struct wait_bit_key {
  25         void                    *flags;
  26         int                     bit_nr;
  27 #define WAIT_ATOMIC_T_BIT_NR    -1
  28 };
  29
  30 struct wait_bit_queue {
  31         struct wait_bit_key     key;
  32         wait_queue_t            wait;
  33 };
  34
  35 struct __wait_queue_head {
  36         spinlock_t              lock;
  37         struct list_head        task_list;
  38 };
  39 typedef struct __wait_queue_head wait_queue_head_t;
  40
  41 struct task_struct;
  42
  43 /*
  44  * Macros for declaration and initialisaton of the datatypes
  45  */
  46
  47 #define __WAITQUEUE_INITIALIZER(name, tsk) {                            \
  48         .private        = tsk,                                          \
  49         .func           = default_wake_function,                        \
  50         .task_list      = { NULL, NULL } }
  51
  52 #define DECLARE_WAITQUEUE(name, tsk)                                    \
  53         wait_queue_t name = __WAITQUEUE_INITIALIZER(name, tsk)
  54
  55 #define __WAIT_QUEUE_HEAD_INITIALIZER(name) {                           \
  56         .lock           = __SPIN_LOCK_UNLOCKED(name.lock),              \
  57         .task_list      = { &(name).task_list, &(name).task_list } }
  58
  59 #define DECLARE_WAIT_QUEUE_HEAD(name) \
  60         wait_queue_head_t name = __WAIT_QUEUE_HEAD_INITIALIZER(name)
  61
  62 #define __WAIT_BIT_KEY_INITIALIZER(word, bit)                           \
  63         { .flags = word, .bit_nr = bit, }
  64
  65 #define __WAIT_ATOMIC_T_KEY_INITIALIZER(p)                              \
  66         { .flags = p, .bit_nr = WAIT_ATOMIC_T_BIT_NR, }
  67
  68 extern void __init_waitqueue_head(wait_queue_head_t *q, const char *name, struct lock_class_key *);
  69
  70 #define init_waitqueue_head(q)                          \
  71         do {                                            \
  72                 static struct lock_class_key __key;     \
  73                                                         \
  74                 __init_waitqueue_head((q), #q, &__key); \
  75         } while (0)
  76
  77 #ifdef CONFIG_LOCKDEP
  78 # define __WAIT_QUEUE_HEAD_INIT_ONSTACK(name) \
  79         ({ init_waitqueue_head(&name); name; })
  80 # define DECLARE_WAIT_QUEUE_HEAD_ONSTACK(name) \
  81         wait_queue_head_t name = __WAIT_QUEUE_HEAD_INIT_ONSTACK(name)
  82 #else
  83 # define DECLARE_WAIT_QUEUE_HEAD_ONSTACK(name) DECLARE_WAIT_QUEUE_HEAD(name)
  84 #endif
  85
  86 static inline void init_waitqueue_entry(wait_queue_t *q, struct task_struct *p)
  87 {
  88         q->flags        = 0;
  89         q->private      = p;
  90         q->func         = default_wake_function;
  91 }
  92
  93 static inline void
  94 init_waitqueue_func_entry(wait_queue_t *q, wait_queue_func_t func)
  95 {
  96         q->flags        = 0;
  97         q->private      = NULL;
  98         q->func         = func;
  99 }
 100
 101 static inline int waitqueue_active(wait_queue_head_t *q)
 102 {
 103         return !list_empty(&q->task_list);
 104 }
 105
 106 extern void add_wait_queue(wait_queue_head_t *q, wait_queue_t *wait);
 107 extern void add_wait_queue_exclusive(wait_queue_head_t *q, wait_queue_t *wait);
 108 extern void remove_wait_queue(wait_queue_head_t *q, wait_queue_t *wait);
 109
 110 static inline void __add_wait_queue(wait_queue_head_t *head, wait_queue_t *new)
 111 {
 112         list_add(&new->task_list, &head->task_list);
 113 }
 114
 115 /*
 116  * Used for wake-one threads:
 117  */
 118 static inline void
 119 __add_wait_queue_exclusive(wait_queue_head_t *q, wait_queue_t *wait)
 120 {
 121         wait->flags |= WQ_FLAG_EXCLUSIVE;
 122         __add_wait_queue(q, wait);
 123 }
 124
 125 static inline void __add_wait_queue_tail(wait_queue_head_t *head,
 126                                          wait_queue_t *new)
 127 {
 128         list_add_tail(&new->task_list, &head->task_list);
 129 }
 130
 131 static inline void
 132 __add_wait_queue_tail_exclusive(wait_queue_head_t *q, wait_queue_t *wait)
 133 {
 134         wait->flags |= WQ_FLAG_EXCLUSIVE;
 135         __add_wait_queue_tail(q, wait);
 136 }
 137
 138 static inline void
 139 __remove_wait_queue(wait_queue_head_t *head, wait_queue_t *old)
 140 {
 141         list_del(&old->task_list);
 142 }
 143
 144 void __wake_up(wait_queue_head_t *q, unsigned int mode, int nr, void *key);
 145 void __wake_up_locked_key(wait_queue_head_t *q, unsigned int mode, void *key);
 146 void __wake_up_sync_key(wait_queue_head_t *q, unsigned int mode, int nr, void *key);
 147 void __wake_up_locked(wait_queue_head_t *q, unsigned int mode, int nr);
 148 void __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr);
 149 void __wake_up_bit(wait_queue_head_t *, void *, int);
 150 int __wait_on_bit(wait_queue_head_t *, struct wait_bit_queue *, int (*)(void *), unsigned);
 151 int __wait_on_bit_lock(wait_queue_head_t *, struct wait_bit_queue *, int (*)(void *), unsigned);
 152 void wake_up_bit(void *, int);
 153 void wake_up_atomic_t(atomic_t *);
 154 int out_of_line_wait_on_bit(void *, int, int (*)(void *), unsigned);
 155 int out_of_line_wait_on_bit_lock(void *, int, int (*)(void *), unsigned);
 156 int out_of_line_wait_on_atomic_t(atomic_t *, int (*)(atomic_t *), unsigned);
 157 wait_queue_head_t *bit_waitqueue(void *, int);
 158
 159 #define wake_up(x)                      __wake_up(x, TASK_NORMAL, 1, NULL)
 160 #define wake_up_nr(x, nr)               __wake_up(x, TASK_NORMAL, nr, NULL)
 161 #define wake_up_all(x)                  __wake_up(x, TASK_NORMAL, 0, NULL)
 162 #define wake_up_locked(x)               __wake_up_locked((x), TASK_NORMAL, 1)
 163 #define wake_up_all_locked(x)           __wake_up_locked((x), TASK_NORMAL, 0)
 164
 165 #define wake_up_interruptible(x)        __wake_up(x, TASK_INTERRUPTIBLE, 1, NULL)
 166 #define wake_up_interruptible_nr(x, nr) __wake_up(x, TASK_INTERRUPTIBLE, nr, NULL)
 167 #define wake_up_interruptible_all(x)    __wake_up(x, TASK_INTERRUPTIBLE, 0, NULL)
 168 #define wake_up_interruptible_sync(x)   __wake_up_sync((x), TASK_INTERRUPTIBLE, 1)
 169
 170 /*
 171  * Wakeup macros to be used to report events to the targets.
 172  */
 173 #define wake_up_poll(x, m)                                              \
 174         __wake_up(x, TASK_NORMAL, 1, (void *) (m))
 175 #define wake_up_locked_poll(x, m)                                       \
 176         __wake_up_locked_key((x), TASK_NORMAL, (void *) (m))
 177 #define wake_up_interruptible_poll(x, m)                                \
 178         __wake_up(x, TASK_INTERRUPTIBLE, 1, (void *) (m))
 179 #define wake_up_interruptible_sync_poll(x, m)                           \
 180         __wake_up_sync_key((x), TASK_INTERRUPTIBLE, 1, (void *) (m))
 181
 182 #define ___wait_cond_timeout(condition)                                 \
 183 ({                                                                      \
 184         bool __cond = (condition);                                      \
 185         if (__cond && !__ret)                                           \
 186                 __ret = 1;                                              \
 187         __cond || !__ret;                                               \
 188 })
 189
 190 #define ___wait_is_interruptible(state)                                 \
 191         (!__builtin_constant_p(state) ||                                \
 192                 state == TASK_INTERRUPTIBLE || state == TASK_KILLABLE)  \
 193
 194 #define ___wait_event(wq, condition, state, exclusive, ret, cmd)        \
 195 ({                                                                      \
 196         __label__ __out;                                                \
 197         wait_queue_t __wait;                                            \
 198         long __ret = ret;                                               \
 199                                                                         \
 200         INIT_LIST_HEAD(&__wait.task_list);                              \
 201         if (exclusive)                                                  \
 202                 __wait.flags = WQ_FLAG_EXCLUSIVE;                       \
 203         else                                                            \
 204                 __wait.flags = 0;                                       \
 205                                                                         \
 206         for (;;) {                                                      \
 207                 long __int = prepare_to_wait_event(&wq, &__wait, state);\
 208                                                                         \
 209                 if (condition)                                          \
 210                         break;                                          \
 211                                                                         \
 212                 if (___wait_is_interruptible(state) && __int) {         \
 213                         __ret = __int;                                  \
 214                         if (exclusive) {                                \
 215                                 abort_exclusive_wait(&wq, &__wait,      \
 216                                                      state, NULL);      \
 217                                 goto __out;                             \
 218                         }                                               \
 219                         break;                                          \
 220                 }                                                       \
 221                                                                         \
 222                 cmd;                                                    \
 223         }                                                               \
 224         finish_wait(&wq, &__wait);                                      \
 225 __out:  __ret;                                                          \
 226 })
 227
 228 #define __wait_event(wq, condition)                                     \
 229         (void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0, 0,  \
 230                             schedule())
 231
 232 /**
 233  * wait_event - sleep until a condition gets true
 234  * @wq: the waitqueue to wait on
 235  * @condition: a C expression for the event to wait for
 236  *
 237  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 238  * @condition evaluates to true. The @condition is checked each time
 239  * the waitqueue @wq is woken up.
 240  *
 241  * wake_up() has to be called after changing any variable that could
 242  * change the result of the wait condition.
 243  */
 244 #define wait_event(wq, condition)                                       \
 245 do {                                                                    \
 246         if (condition)                                                  \
 247                 break;                                                  \
 248         __wait_event(wq, condition);                                    \
 249 } while (0)
 250
 251 #define __wait_event_timeout(wq, condition, timeout)                    \
 252         ___wait_event(wq, ___wait_cond_timeout(condition),              \
 253                       TASK_UNINTERRUPTIBLE, 0, timeout,                 \
 254                       __ret = schedule_timeout(__ret))
 255
 256 /**
 257  * wait_event_timeout - sleep until a condition gets true or a timeout elapses
 258  * @wq: the waitqueue to wait on
 259  * @condition: a C expression for the event to wait for
 260  * @timeout: timeout, in jiffies
 261  *
 262  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 263  * @condition evaluates to true. The @condition is checked each time
 264  * the waitqueue @wq is woken up.
 265  *
 266  * wake_up() has to be called after changing any variable that could
 267  * change the result of the wait condition.
 268  *
 269  * The function returns 0 if the @timeout elapsed, or the remaining
 270  * jiffies (at least 1) if the @condition evaluated to %true before
 271  * the @timeout elapsed.
 272  */
 273 #define wait_event_timeout(wq, condition, timeout)                      \
 274 ({                                                                      \
 275         long __ret = timeout;                                           \
 276         if (!___wait_cond_timeout(condition))                           \
 277                 __ret = __wait_event_timeout(wq, condition, timeout);   \
 278         __ret;                                                          \
 279 })
 280
 281 #define __wait_event_cmd(wq, condition, cmd1, cmd2)                     \
 282 do {                                                                    \
 283         DEFINE_WAIT(__wait);                                            \
 284                                                                         \
 285         for (;;) {                                                      \
 286                 prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE);    \
 287                 if (condition)                                          \
 288                         break;                                          \
 289                 cmd1;                                                   \
 290                 schedule();                                             \
 291                 cmd2;                                                   \
 292         }                                                               \
 293         finish_wait(&wq, &__wait);                                      \
 294 } while (0)
 295
 296 /**
 297  * wait_event_cmd - 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  * cmd1: the command will be executed before sleep
 301  * cmd2: the command will be executed after sleep
 302  *
 303  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 304  * @condition evaluates to true. The @condition is checked each time
 305  * the waitqueue @wq is woken up.
 306  *
 307  * wake_up() has to be called after changing any variable that could
 308  * change the result of the wait condition.
 309  */
 310 #define wait_event_cmd(wq, condition, cmd1, cmd2)                       \
 311 do {                                                                    \
 312         if (condition)                                                  \
 313                 break;                                                  \
 314         __wait_event_cmd(wq, condition, cmd1, cmd2);                    \
 315 } while (0)
 316
 317 #define __wait_event_interruptible(wq, condition)                       \
 318         ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 0, 0,          \
 319                       schedule())
 320
 321 /**
 322  * wait_event_interruptible - sleep until a condition gets true
 323  * @wq: the waitqueue to wait on
 324  * @condition: a C expression for the event to wait for
 325  *
 326  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 327  * @condition evaluates to true or a signal is received.
 328  * The @condition is checked each time the waitqueue @wq is woken up.
 329  *
 330  * wake_up() has to be called after changing any variable that could
 331  * change the result of the wait condition.
 332  *
 333  * The function will return -ERESTARTSYS if it was interrupted by a
 334  * signal and 0 if @condition evaluated to true.
 335  */
 336 #define wait_event_interruptible(wq, condition)                         \
 337 ({                                                                      \
 338         int __ret = 0;                                                  \
 339         if (!(condition))                                               \
 340                 __ret = __wait_event_interruptible(wq, condition);      \
 341         __ret;                                                          \
 342 })
 343
 344 #define __wait_event_interruptible_timeout(wq, condition, timeout)      \
 345         ___wait_event(wq, ___wait_cond_timeout(condition),              \
 346                       TASK_INTERRUPTIBLE, 0, timeout,                   \
 347                       __ret = schedule_timeout(__ret))
 348
 349 /**
 350  * wait_event_interruptible_timeout - sleep until a condition gets true or a timeout elapses
 351  * @wq: the waitqueue to wait on
 352  * @condition: a C expression for the event to wait for
 353  * @timeout: timeout, in jiffies
 354  *
 355  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 356  * @condition evaluates to true or a signal is received.
 357  * The @condition is checked each time the waitqueue @wq is woken up.
 358  *
 359  * wake_up() has to be called after changing any variable that could
 360  * change the result of the wait condition.
 361  *
 362  * Returns:
 363  * 0 if the @timeout elapsed, -%ERESTARTSYS if it was interrupted by
 364  * a signal, or the remaining jiffies (at least 1) if the @condition
 365  * evaluated to %true before the @timeout elapsed.
 366  */
 367 #define wait_event_interruptible_timeout(wq, condition, timeout)        \
 368 ({                                                                      \
 369         long __ret = timeout;                                           \
 370         if (!___wait_cond_timeout(condition))                           \
 371                 __ret = __wait_event_interruptible_timeout(wq,          \
 372                                                 condition, timeout);    \
 373         __ret;                                                          \
 374 })
 375
 376 #define __wait_event_hrtimeout(wq, condition, timeout, state)           \
 377 ({                                                                      \
 378         int __ret = 0;                                                  \
 379         struct hrtimer_sleeper __t;                                     \
 380                                                                         \
 381         hrtimer_init_on_stack(&__t.timer, CLOCK_MONOTONIC,              \
 382                               HRTIMER_MODE_REL);                        \
 383         hrtimer_init_sleeper(&__t, current);                            \
 384         if ((timeout).tv64 != KTIME_MAX)                                \
 385                 hrtimer_start_range_ns(&__t.timer, timeout,             \
 386                                        current->timer_slack_ns,         \
 387                                        HRTIMER_MODE_REL);               \
 388                                                                         \
 389         __ret = ___wait_event(wq, condition, state, 0, 0,               \
 390                 if (!__t.task) {                                        \
 391                         __ret = -ETIME;                                 \
 392                         break;                                          \
 393                 }                                                       \
 394                 schedule());                                            \
 395                                                                         \
 396         hrtimer_cancel(&__t.timer);                                     \
 397         destroy_hrtimer_on_stack(&__t.timer);                           \
 398         __ret;                                                          \
 399 })
 400
 401 /**
 402  * wait_event_hrtimeout - sleep until a condition gets true or a timeout elapses
 403  * @wq: the waitqueue to wait on
 404  * @condition: a C expression for the event to wait for
 405  * @timeout: timeout, as a ktime_t
 406  *
 407  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 408  * @condition evaluates to true or a signal is received.
 409  * The @condition is checked each time the waitqueue @wq is woken up.
 410  *
 411  * wake_up() has to be called after changing any variable that could
 412  * change the result of the wait condition.
 413  *
 414  * The function returns 0 if @condition became true, or -ETIME if the timeout
 415  * elapsed.
 416  */
 417 #define wait_event_hrtimeout(wq, condition, timeout)                    \
 418 ({                                                                      \
 419         int __ret = 0;                                                  \
 420         if (!(condition))                                               \
 421                 __ret = __wait_event_hrtimeout(wq, condition, timeout,  \
 422                                                TASK_UNINTERRUPTIBLE);   \
 423         __ret;                                                          \
 424 })
 425
 426 /**
 427  * wait_event_interruptible_hrtimeout - sleep until a condition gets true or a timeout elapses
 428  * @wq: the waitqueue to wait on
 429  * @condition: a C expression for the event to wait for
 430  * @timeout: timeout, as a ktime_t
 431  *
 432  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 433  * @condition evaluates to true or a signal is received.
 434  * The @condition is checked each time the waitqueue @wq is woken up.
 435  *
 436  * wake_up() has to be called after changing any variable that could
 437  * change the result of the wait condition.
 438  *
 439  * The function returns 0 if @condition became true, -ERESTARTSYS if it was
 440  * interrupted by a signal, or -ETIME if the timeout elapsed.
 441  */
 442 #define wait_event_interruptible_hrtimeout(wq, condition, timeout)      \
 443 ({                                                                      \
 444         long __ret = 0;                                                 \
 445         if (!(condition))                                               \
 446                 __ret = __wait_event_hrtimeout(wq, condition, timeout,  \
 447                                                TASK_INTERRUPTIBLE);     \
 448         __ret;                                                          \
 449 })
 450
 451 #define __wait_event_interruptible_exclusive(wq, condition)             \
 452         ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 1, 0,          \
 453                       schedule())
 454
 455 #define wait_event_interruptible_exclusive(wq, condition)               \
 456 ({                                                                      \
 457         int __ret = 0;                                                  \
 458         if (!(condition))                                               \
 459                 __ret = __wait_event_interruptible_exclusive(wq, condition);\
 460         __ret;                                                          \
 461 })
 462
 463
 464 #define __wait_event_interruptible_locked(wq, condition, exclusive, irq) \
 465 ({                                                                      \
 466         int __ret = 0;                                                  \
 467         DEFINE_WAIT(__wait);                                            \
 468         if (exclusive)                                                  \
 469                 __wait.flags |= WQ_FLAG_EXCLUSIVE;                      \
 470         do {                                                            \
 471                 if (likely(list_empty(&__wait.task_list)))              \
 472                         __add_wait_queue_tail(&(wq), &__wait);          \
 473                 set_current_state(TASK_INTERRUPTIBLE);                  \
 474                 if (signal_pending(current)) {                          \
 475                         __ret = -ERESTARTSYS;                           \
 476                         break;                                          \
 477                 }                                                       \
 478                 if (irq)                                                \
 479                         spin_unlock_irq(&(wq).lock);                    \
 480                 else                                                    \
 481                         spin_unlock(&(wq).lock);                        \
 482                 schedule();                                             \
 483                 if (irq)                                                \
 484                         spin_lock_irq(&(wq).lock);                      \
 485                 else                                                    \
 486                         spin_lock(&(wq).lock);                          \
 487         } while (!(condition));                                         \
 488         __remove_wait_queue(&(wq), &__wait);                            \
 489         __set_current_state(TASK_RUNNING);                              \
 490         __ret;                                                          \
 491 })
 492
 493
 494 /**
 495  * wait_event_interruptible_locked - sleep until a condition gets true
 496  * @wq: the waitqueue to wait on
 497  * @condition: a C expression for the event to wait for
 498  *
 499  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 500  * @condition evaluates to true or a signal is received.
 501  * The @condition is checked each time the waitqueue @wq is woken up.
 502  *
 503  * It must be called with wq.lock being held.  This spinlock is
 504  * unlocked while sleeping but @condition testing is done while lock
 505  * is held and when this macro exits the lock is held.
 506  *
 507  * The lock is locked/unlocked using spin_lock()/spin_unlock()
 508  * functions which must match the way they are locked/unlocked outside
 509  * of this macro.
 510  *
 511  * wake_up_locked() has to be called after changing any variable that could
 512  * change the result of the wait condition.
 513  *
 514  * The function will return -ERESTARTSYS if it was interrupted by a
 515  * signal and 0 if @condition evaluated to true.
 516  */
 517 #define wait_event_interruptible_locked(wq, condition)                  \
 518         ((condition)                                                    \
 519          ? 0 : __wait_event_interruptible_locked(wq, condition, 0, 0))
 520
 521 /**
 522  * wait_event_interruptible_locked_irq - sleep until a condition gets true
 523  * @wq: the waitqueue to wait on
 524  * @condition: a C expression for the event to wait for
 525  *
 526  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 527  * @condition evaluates to true or a signal is received.
 528  * The @condition is checked each time the waitqueue @wq is woken up.
 529  *
 530  * It must be called with wq.lock being held.  This spinlock is
 531  * unlocked while sleeping but @condition testing is done while lock
 532  * is held and when this macro exits the lock is held.
 533  *
 534  * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq()
 535  * functions which must match the way they are locked/unlocked outside
 536  * of this macro.
 537  *
 538  * wake_up_locked() has to be called after changing any variable that could
 539  * change the result of the wait condition.
 540  *
 541  * The function will return -ERESTARTSYS if it was interrupted by a
 542  * signal and 0 if @condition evaluated to true.
 543  */
 544 #define wait_event_interruptible_locked_irq(wq, condition)              \
 545         ((condition)                                                    \
 546          ? 0 : __wait_event_interruptible_locked(wq, condition, 0, 1))
 547
 548 /**
 549  * wait_event_interruptible_exclusive_locked - sleep exclusively until a condition gets true
 550  * @wq: the waitqueue to wait on
 551  * @condition: a C expression for the event to wait for
 552  *
 553  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 554  * @condition evaluates to true or a signal is received.
 555  * The @condition is checked each time the waitqueue @wq is woken up.
 556  *
 557  * It must be called with wq.lock being held.  This spinlock is
 558  * unlocked while sleeping but @condition testing is done while lock
 559  * is held and when this macro exits the lock is held.
 560  *
 561  * The lock is locked/unlocked using spin_lock()/spin_unlock()
 562  * functions which must match the way they are locked/unlocked outside
 563  * of this macro.
 564  *
 565  * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
 566  * set thus when other process waits process on the list if this
 567  * process is awaken further processes are not considered.
 568  *
 569  * wake_up_locked() has to be called after changing any variable that could
 570  * change the result of the wait condition.
 571  *
 572  * The function will return -ERESTARTSYS if it was interrupted by a
 573  * signal and 0 if @condition evaluated to true.
 574  */
 575 #define wait_event_interruptible_exclusive_locked(wq, condition)        \
 576         ((condition)                                                    \
 577          ? 0 : __wait_event_interruptible_locked(wq, condition, 1, 0))
 578
 579 /**
 580  * wait_event_interruptible_exclusive_locked_irq - sleep until a condition gets true
 581  * @wq: the waitqueue to wait on
 582  * @condition: a C expression for the event to wait for
 583  *
 584  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 585  * @condition evaluates to true or a signal is received.
 586  * The @condition is checked each time the waitqueue @wq is woken up.
 587  *
 588  * It must be called with wq.lock being held.  This spinlock is
 589  * unlocked while sleeping but @condition testing is done while lock
 590  * is held and when this macro exits the lock is held.
 591  *
 592  * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq()
 593  * functions which must match the way they are locked/unlocked outside
 594  * of this macro.
 595  *
 596  * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
 597  * set thus when other process waits process on the list if this
 598  * process is awaken further processes are not considered.
 599  *
 600  * wake_up_locked() has to be called after changing any variable that could
 601  * change the result of the wait condition.
 602  *
 603  * The function will return -ERESTARTSYS if it was interrupted by a
 604  * signal and 0 if @condition evaluated to true.
 605  */
 606 #define wait_event_interruptible_exclusive_locked_irq(wq, condition)    \
 607         ((condition)                                                    \
 608          ? 0 : __wait_event_interruptible_locked(wq, condition, 1, 1))
 609
 610
 611 #define __wait_event_killable(wq, condition)                            \
 612         ___wait_event(wq, condition, TASK_KILLABLE, 0, 0, schedule())
 613
 614 /**
 615  * wait_event_killable - sleep until a condition gets true
 616  * @wq: the waitqueue to wait on
 617  * @condition: a C expression for the event to wait for
 618  *
 619  * The process is put to sleep (TASK_KILLABLE) until the
 620  * @condition evaluates to true or a signal is received.
 621  * The @condition is checked each time the waitqueue @wq is woken up.
 622  *
 623  * wake_up() has to be called after changing any variable that could
 624  * change the result of the wait condition.
 625  *
 626  * The function will return -ERESTARTSYS if it was interrupted by a
 627  * signal and 0 if @condition evaluated to true.
 628  */
 629 #define wait_event_killable(wq, condition)                              \
 630 ({                                                                      \
 631         int __ret = 0;                                                  \
 632         if (!(condition))                                               \
 633                 __ret = __wait_event_killable(wq, condition);           \
 634         __ret;                                                          \
 635 })
 636
 637
 638 #define __wait_event_lock_irq(wq, condition, lock, cmd)                 \
 639         (void)___wait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0, 0,  \
 640                             spin_unlock_irq(&lock);                     \
 641                             cmd;                                        \
 642                             schedule();                                 \
 643                             spin_lock_irq(&lock))
 644
 645 /**
 646  * wait_event_lock_irq_cmd - sleep until a condition gets true. The
 647  *                           condition is checked under the lock. This
 648  *                           is expected to be called with the lock
 649  *                           taken.
 650  * @wq: the waitqueue to wait on
 651  * @condition: a C expression for the event to wait for
 652  * @lock: a locked spinlock_t, which will be released before cmd
 653  *        and schedule() and reacquired afterwards.
 654  * @cmd: a command which is invoked outside the critical section before
 655  *       sleep
 656  *
 657  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 658  * @condition evaluates to true. The @condition is checked each time
 659  * the waitqueue @wq is woken up.
 660  *
 661  * wake_up() has to be called after changing any variable that could
 662  * change the result of the wait condition.
 663  *
 664  * This is supposed to be called while holding the lock. The lock is
 665  * dropped before invoking the cmd and going to sleep and is reacquired
 666  * afterwards.
 667  */
 668 #define wait_event_lock_irq_cmd(wq, condition, lock, cmd)               \
 669 do {                                                                    \
 670         if (condition)                                                  \
 671                 break;                                                  \
 672         __wait_event_lock_irq(wq, condition, lock, cmd);                \
 673 } while (0)
 674
 675 /**
 676  * wait_event_lock_irq - sleep until a condition gets true. The
 677  *                       condition is checked under the lock. This
 678  *                       is expected to be called with the lock
 679  *                       taken.
 680  * @wq: the waitqueue to wait on
 681  * @condition: a C expression for the event to wait for
 682  * @lock: a locked spinlock_t, which will be released before schedule()
 683  *        and reacquired afterwards.
 684  *
 685  * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 686  * @condition evaluates to true. The @condition is checked each time
 687  * the waitqueue @wq is woken up.
 688  *
 689  * wake_up() has to be called after changing any variable that could
 690  * change the result of the wait condition.
 691  *
 692  * This is supposed to be called while holding the lock. The lock is
 693  * dropped before going to sleep and is reacquired afterwards.
 694  */
 695 #define wait_event_lock_irq(wq, condition, lock)                        \
 696 do {                                                                    \
 697         if (condition)                                                  \
 698                 break;                                                  \
 699         __wait_event_lock_irq(wq, condition, lock, );                   \
 700 } while (0)
 701
 702
 703 #define __wait_event_interruptible_lock_irq(wq, condition, lock, cmd)   \
 704         ___wait_event(wq, condition, TASK_INTERRUPTIBLE, 0, 0,          \
 705                       spin_unlock_irq(&lock);                           \
 706                       cmd;                                              \
 707                       schedule();                                       \
 708                       spin_lock_irq(&lock))
 709
 710 /**
 711  * wait_event_interruptible_lock_irq_cmd - sleep until a condition gets true.
 712  *              The condition is checked under the lock. This is expected to
 713  *              be called with the lock taken.
 714  * @wq: the waitqueue to wait on
 715  * @condition: a C expression for the event to wait for
 716  * @lock: a locked spinlock_t, which will be released before cmd and
 717  *        schedule() and reacquired afterwards.
 718  * @cmd: a command which is invoked outside the critical section before
 719  *       sleep
 720  *
 721  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 722  * @condition evaluates to true or a signal is received. The @condition is
 723  * checked each time the waitqueue @wq is woken up.
 724  *
 725  * wake_up() has to be called after changing any variable that could
 726  * change the result of the wait condition.
 727  *
 728  * This is supposed to be called while holding the lock. The lock is
 729  * dropped before invoking the cmd and going to sleep and is reacquired
 730  * afterwards.
 731  *
 732  * The macro will return -ERESTARTSYS if it was interrupted by a signal
 733  * and 0 if @condition evaluated to true.
 734  */
 735 #define wait_event_interruptible_lock_irq_cmd(wq, condition, lock, cmd) \
 736 ({                                                                      \
 737         int __ret = 0;                                                  \
 738         if (!(condition))                                               \
 739                 __ret = __wait_event_interruptible_lock_irq(wq,         \
 740                                                 condition, lock, cmd);  \
 741         __ret;                                                          \
 742 })
 743
 744 /**
 745  * wait_event_interruptible_lock_irq - sleep until a condition gets true.
 746  *              The condition is checked under the lock. This is expected
 747  *              to be called with the lock taken.
 748  * @wq: the waitqueue to wait on
 749  * @condition: a C expression for the event to wait for
 750  * @lock: a locked spinlock_t, which will be released before schedule()
 751  *        and reacquired afterwards.
 752  *
 753  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 754  * @condition evaluates to true or signal is received. The @condition is
 755  * checked each time the waitqueue @wq is woken up.
 756  *
 757  * wake_up() has to be called after changing any variable that could
 758  * change the result of the wait condition.
 759  *
 760  * This is supposed to be called while holding the lock. The lock is
 761  * dropped before going to sleep and is reacquired afterwards.
 762  *
 763  * The macro will return -ERESTARTSYS if it was interrupted by a signal
 764  * and 0 if @condition evaluated to true.
 765  */
 766 #define wait_event_interruptible_lock_irq(wq, condition, lock)          \
 767 ({                                                                      \
 768         int __ret = 0;                                                  \
 769         if (!(condition))                                               \
 770                 __ret = __wait_event_interruptible_lock_irq(wq,         \
 771                                                 condition, lock,)       \
 772         __ret;                                                          \
 773 })
 774
 775 #define __wait_event_interruptible_lock_irq_timeout(wq, condition,      \
 776                                                     lock, timeout)      \
 777         ___wait_event(wq, ___wait_cond_timeout(condition),              \
 778                       TASK_INTERRUPTIBLE, 0, ret,                       \
 779                       spin_unlock_irq(&lock);                           \
 780                       __ret = schedule_timeout(__ret);                  \
 781                       spin_lock_irq(&lock));
 782
 783 /**
 784  * wait_event_interruptible_lock_irq_timeout - sleep until a condition gets
 785  *              true or a timeout elapses. The condition is checked under
 786  *              the lock. This is expected to be called with the lock taken.
 787  * @wq: the waitqueue to wait on
 788  * @condition: a C expression for the event to wait for
 789  * @lock: a locked spinlock_t, which will be released before schedule()
 790  *        and reacquired afterwards.
 791  * @timeout: timeout, in jiffies
 792  *
 793  * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 794  * @condition evaluates to true or signal is received. The @condition is
 795  * checked each time the waitqueue @wq is woken up.
 796  *
 797  * wake_up() has to be called after changing any variable that could
 798  * change the result of the wait condition.
 799  *
 800  * This is supposed to be called while holding the lock. The lock is
 801  * dropped before going to sleep and is reacquired afterwards.
 802  *
 803  * The function returns 0 if the @timeout elapsed, -ERESTARTSYS if it
 804  * was interrupted by a signal, and the remaining jiffies otherwise
 805  * if the condition evaluated to true before the timeout elapsed.
 806  */
 807 #define wait_event_interruptible_lock_irq_timeout(wq, condition, lock,  \
 808                                                   timeout)              \
 809 ({                                                                      \
 810         long __ret = timeout;                                           \
 811         if (!___wait_cond_timeout(condition))                           \
 812                 __ret = __wait_event_interruptible_lock_irq_timeout(    \
 813                                         wq, condition, lock, timeout);  \
 814         __ret;                                                          \
 815 })
 816
 817
 818 /*
 819  * These are the old interfaces to sleep waiting for an event.
 820  * They are racy.  DO NOT use them, use the wait_event* interfaces above.
 821  * We plan to remove these interfaces.
 822  */
 823 extern void sleep_on(wait_queue_head_t *q);
 824 extern long sleep_on_timeout(wait_queue_head_t *q, signed long timeout);
 825 extern void interruptible_sleep_on(wait_queue_head_t *q);
 826 extern long interruptible_sleep_on_timeout(wait_queue_head_t *q, signed long timeout);
 827
 828 /*
 829  * Waitqueues which are removed from the waitqueue_head at wakeup time
 830  */
 831 void prepare_to_wait(wait_queue_head_t *q, wait_queue_t *wait, int state);
 832 void prepare_to_wait_exclusive(wait_queue_head_t *q, wait_queue_t *wait, int state);
 833 long prepare_to_wait_event(wait_queue_head_t *q, wait_queue_t *wait, int state);
 834 void finish_wait(wait_queue_head_t *q, wait_queue_t *wait);
 835 void abort_exclusive_wait(wait_queue_head_t *q, wait_queue_t *wait, unsigned int mode, void *key);
 836 int autoremove_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 837 int wake_bit_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
 838
 839 #define DEFINE_WAIT_FUNC(name, function)                                \
 840         wait_queue_t name = {                                           \
 841                 .private        = current,                              \
 842                 .func           = function,                             \
 843                 .task_list      = LIST_HEAD_INIT((name).task_list),     \
 844         }
 845
 846 #define DEFINE_WAIT(name) DEFINE_WAIT_FUNC(name, autoremove_wake_function)
 847
 848 #define DEFINE_WAIT_BIT(name, word, bit)                                \
 849         struct wait_bit_queue name = {                                  \
 850                 .key = __WAIT_BIT_KEY_INITIALIZER(word, bit),           \
 851                 .wait   = {                                             \
 852                         .private        = current,                      \
 853                         .func           = wake_bit_function,            \
 854                         .task_list      =                               \
 855                                 LIST_HEAD_INIT((name).wait.task_list),  \
 856                 },                                                      \
 857         }
 858
 859 #define init_wait(wait)                                                 \
 860         do {                                                            \
 861                 (wait)->private = current;                              \
 862                 (wait)->func = autoremove_wake_function;                \
 863                 INIT_LIST_HEAD(&(wait)->task_list);                     \
 864                 (wait)->flags = 0;                                      \
 865         } while (0)
 866
 867 /**
 868  * wait_on_bit - wait for a bit to be cleared
 869  * @word: the word being waited on, a kernel virtual address
 870  * @bit: the bit of the word being waited on
 871  * @action: the function used to sleep, which may take special actions
 872  * @mode: the task state to sleep in
 873  *
 874  * There is a standard hashed waitqueue table for generic use. This
 875  * is the part of the hashtable's accessor API that waits on a bit.
 876  * For instance, if one were to have waiters on a bitflag, one would
 877  * call wait_on_bit() in threads waiting for the bit to clear.
 878  * One uses wait_on_bit() where one is waiting for the bit to clear,
 879  * but has no intention of setting it.
 880  */
 881 static inline int
 882 wait_on_bit(void *word, int bit, int (*action)(void *), unsigned mode)
 883 {
 884         if (!test_bit(bit, word))
 885                 return 0;
 886         return out_of_line_wait_on_bit(word, bit, action, mode);
 887 }
 888
 889 /**
 890  * wait_on_bit_lock - wait for a bit to be cleared, when wanting to set it
 891  * @word: the word being waited on, a kernel virtual address
 892  * @bit: the bit of the word being waited on
 893  * @action: the function used to sleep, which may take special actions
 894  * @mode: the task state to sleep in
 895  *
 896  * There is a standard hashed waitqueue table for generic use. This
 897  * is the part of the hashtable's accessor API that waits on a bit
 898  * when one intends to set it, for instance, trying to lock bitflags.
 899  * For instance, if one were to have waiters trying to set bitflag
 900  * and waiting for it to clear before setting it, one would call
 901  * wait_on_bit() in threads waiting to be able to set the bit.
 902  * One uses wait_on_bit_lock() where one is waiting for the bit to
 903  * clear with the intention of setting it, and when done, clearing it.
 904  */
 905 static inline int
 906 wait_on_bit_lock(void *word, int bit, int (*action)(void *), unsigned mode)
 907 {
 908         if (!test_and_set_bit(bit, word))
 909                 return 0;
 910         return out_of_line_wait_on_bit_lock(word, bit, action, mode);
 911 }
 912
 913 /**
 914  * wait_on_atomic_t - Wait for an atomic_t to become 0
 915  * @val: The atomic value being waited on, a kernel virtual address
 916  * @action: the function used to sleep, which may take special actions
 917  * @mode: the task state to sleep in
 918  *
 919  * Wait for an atomic_t to become 0.  We abuse the bit-wait waitqueue table for
 920  * the purpose of getting a waitqueue, but we set the key to a bit number
 921  * outside of the target 'word'.
 922  */
 923 static inline
 924 int wait_on_atomic_t(atomic_t *val, int (*action)(atomic_t *), unsigned mode)
 925 {
 926         if (atomic_read(val) == 0)
 927                 return 0;
 928         return out_of_line_wait_on_atomic_t(val, action, mode);
 929 }
 930
 931 #endif /* _LINUX_WAIT_H */