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