include/linux/wait.h

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