1#ifndef _LINUX_WAIT_H 2#define _LINUX_WAIT_H 3 4#define WNOHANG 0x00000001 5#define WUNTRACED 0x00000002 6#define WSTOPPED WUNTRACED 7#define WEXITED 0x00000004 8#define WCONTINUED 0x00000008 9#define WNOWAIT 0x01000000 /* Don't reap, just poll status. */ 10 11#define __WNOTHREAD 0x20000000 /* Don't wait on children of other threads in this group */ 12#define __WALL 0x40000000 /* Wait on all children, regardless of type */ 13#define __WCLONE 0x80000000 /* Wait only on non-SIGCHLD children */ 14 15/* First argument to waitid: */ 16#define P_ALL 0 17#define P_PID 1 18#define P_PGID 2 19 20#ifdef __KERNEL__ 21 22#include <linux/list.h> 23#include <linux/stddef.h> 24#include <linux/spinlock.h> 25#include <asm/current.h> 26 27typedef struct __wait_queue wait_queue_t; 28typedef int (*wait_queue_func_t)(wait_queue_t *wait, unsigned mode, int flags, void *key); 29int default_wake_function(wait_queue_t *wait, unsigned mode, int flags, void *key); 30 31struct __wait_queue { 32 unsigned int flags; 33#define WQ_FLAG_EXCLUSIVE 0x01 34 void *private; 35 wait_queue_func_t func; 36 struct list_head task_list; 37}; 38 39struct wait_bit_key { 40 void *flags; 41 int bit_nr; 42}; 43 44struct wait_bit_queue { 45 struct wait_bit_key key; 46 wait_queue_t wait; 47}; 48 49struct __wait_queue_head { 50 spinlock_t lock; 51 struct list_head task_list; 52}; 53typedef struct __wait_queue_head wait_queue_head_t; 54 55struct task_struct; 56 57/* 58 * Macros for declaration and initialisaton of the datatypes 59 */ 60 61#define __WAITQUEUE_INITIALIZER(name, tsk) { \ 62 .private = tsk, \ 63 .func = default_wake_function, \ 64 .task_list = { NULL, NULL } } 65 66#define DECLARE_WAITQUEUE(name, tsk) \ 67 wait_queue_t name = __WAITQUEUE_INITIALIZER(name, tsk) 68 69#define __WAIT_QUEUE_HEAD_INITIALIZER(name) { \ 70 .lock = __SPIN_LOCK_UNLOCKED(name.lock), \ 71 .task_list = { &(name).task_list, &(name).task_list } } 72 73#define DECLARE_WAIT_QUEUE_HEAD(name) \ 74 wait_queue_head_t name = __WAIT_QUEUE_HEAD_INITIALIZER(name) 75 76#define __WAIT_BIT_KEY_INITIALIZER(word, bit) \ 77 { .flags = word, .bit_nr = bit, } 78 79extern void __init_waitqueue_head(wait_queue_head_t *q, const char *name, struct lock_class_key *); 80 81#define init_waitqueue_head(q) \ 82 do { \ 83 static struct lock_class_key __key; \ 84 \ 85 __init_waitqueue_head((q), #q, &__key); \ 86 } while (0) 87 88#ifdef CONFIG_LOCKDEP 89# define __WAIT_QUEUE_HEAD_INIT_ONSTACK(name) \ 90 ({ init_waitqueue_head(&name); name; }) 91# define DECLARE_WAIT_QUEUE_HEAD_ONSTACK(name) \ 92 wait_queue_head_t name = __WAIT_QUEUE_HEAD_INIT_ONSTACK(name) 93#else 94# define DECLARE_WAIT_QUEUE_HEAD_ONSTACK(name) DECLARE_WAIT_QUEUE_HEAD(name) 95#endif 96 97static inline void init_waitqueue_entry(wait_queue_t *q, struct task_struct *p) 98{ 99 q->flags = 0; 100 q->private = p; 101 q->func = default_wake_function; 102} 103 104static inline void init_waitqueue_func_entry(wait_queue_t *q, 105 wait_queue_func_t func) 106{ 107 q->flags = 0; 108 q->private = NULL; 109 q->func = func; 110} 111 112static inline int waitqueue_active(wait_queue_head_t *q) 113{ 114 return !list_empty(&q->task_list); 115} 116 117extern void add_wait_queue(wait_queue_head_t *q, wait_queue_t *wait); 118extern void add_wait_queue_exclusive(wait_queue_head_t *q, wait_queue_t *wait); 119extern void remove_wait_queue(wait_queue_head_t *q, wait_queue_t *wait); 120 121static inline void __add_wait_queue(wait_queue_head_t *head, wait_queue_t *new) 122{ 123 list_add(&new->task_list, &head->task_list); 124} 125 126/* 127 * Used for wake-one threads: 128 */ 129static inline void __add_wait_queue_exclusive(wait_queue_head_t *q, 130 wait_queue_t *wait) 131{ 132 wait->flags |= WQ_FLAG_EXCLUSIVE; 133 __add_wait_queue(q, wait); 134} 135 136static inline void __add_wait_queue_tail(wait_queue_head_t *head, 137 wait_queue_t *new) 138{ 139 list_add_tail(&new->task_list, &head->task_list); 140} 141 142static inline void __add_wait_queue_tail_exclusive(wait_queue_head_t *q, 143 wait_queue_t *wait) 144{ 145 wait->flags |= WQ_FLAG_EXCLUSIVE; 146 __add_wait_queue_tail(q, wait); 147} 148 149static inline void __remove_wait_queue(wait_queue_head_t *head, 150 wait_queue_t *old) 151{ 152 list_del(&old->task_list); 153} 154 155void __wake_up(wait_queue_head_t *q, unsigned int mode, int nr, void *key); 156void __wake_up_locked_key(wait_queue_head_t *q, unsigned int mode, void *key); 157void __wake_up_sync_key(wait_queue_head_t *q, unsigned int mode, int nr, 158 void *key); 159void __wake_up_locked(wait_queue_head_t *q, unsigned int mode, int nr); 160void __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr); 161void __wake_up_bit(wait_queue_head_t *, void *, int); 162int __wait_on_bit(wait_queue_head_t *, struct wait_bit_queue *, int (*)(void *), unsigned); 163int __wait_on_bit_lock(wait_queue_head_t *, struct wait_bit_queue *, int (*)(void *), unsigned); 164void wake_up_bit(void *, int); 165int out_of_line_wait_on_bit(void *, int, int (*)(void *), unsigned); 166int out_of_line_wait_on_bit_lock(void *, int, int (*)(void *), unsigned); 167wait_queue_head_t *bit_waitqueue(void *, int); 168 169#define wake_up(x) __wake_up(x, TASK_NORMAL, 1, NULL) 170#define wake_up_nr(x, nr) __wake_up(x, TASK_NORMAL, nr, NULL) 171#define wake_up_all(x) __wake_up(x, TASK_NORMAL, 0, NULL) 172#define wake_up_locked(x) __wake_up_locked((x), TASK_NORMAL, 1) 173#define wake_up_all_locked(x) __wake_up_locked((x), TASK_NORMAL, 0) 174 175#define wake_up_interruptible(x) __wake_up(x, TASK_INTERRUPTIBLE, 1, NULL) 176#define wake_up_interruptible_nr(x, nr) __wake_up(x, TASK_INTERRUPTIBLE, nr, NULL) 177#define wake_up_interruptible_all(x) __wake_up(x, TASK_INTERRUPTIBLE, 0, NULL) 178#define wake_up_interruptible_sync(x) __wake_up_sync((x), TASK_INTERRUPTIBLE, 1) 179 180/* 181 * Wakeup macros to be used to report events to the targets. 182 */ 183#define wake_up_poll(x, m) \ 184 __wake_up(x, TASK_NORMAL, 1, (void *) (m)) 185#define wake_up_locked_poll(x, m) \ 186 __wake_up_locked_key((x), TASK_NORMAL, (void *) (m)) 187#define wake_up_interruptible_poll(x, m) \ 188 __wake_up(x, TASK_INTERRUPTIBLE, 1, (void *) (m)) 189#define wake_up_interruptible_sync_poll(x, m) \ 190 __wake_up_sync_key((x), TASK_INTERRUPTIBLE, 1, (void *) (m)) 191 192#define __wait_event(wq, condition) \ 193do { \ 194 DEFINE_WAIT(__wait); \ 195 \ 196 for (;;) { \ 197 prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE); \ 198 if (condition) \ 199 break; \ 200 schedule(); \ 201 } \ 202 finish_wait(&wq, &__wait); \ 203} while (0) 204 205/** 206 * wait_event - sleep until a condition gets true 207 * @wq: the waitqueue to wait on 208 * @condition: a C expression for the event to wait for 209 * 210 * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the 211 * @condition evaluates to true. The @condition is checked each time 212 * the waitqueue @wq is woken up. 213 * 214 * wake_up() has to be called after changing any variable that could 215 * change the result of the wait condition. 216 */ 217#define wait_event(wq, condition) \ 218do { \ 219 if (condition) \ 220 break; \ 221 __wait_event(wq, condition); \ 222} while (0) 223 224#define __wait_event_timeout(wq, condition, ret) \ 225do { \ 226 DEFINE_WAIT(__wait); \ 227 \ 228 for (;;) { \ 229 prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE); \ 230 if (condition) \ 231 break; \ 232 ret = schedule_timeout(ret); \ 233 if (!ret) \ 234 break; \ 235 } \ 236 finish_wait(&wq, &__wait); \ 237} while (0) 238 239/** 240 * wait_event_timeout - sleep until a condition gets true or a timeout elapses 241 * @wq: the waitqueue to wait on 242 * @condition: a C expression for the event to wait for 243 * @timeout: timeout, in jiffies 244 * 245 * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the 246 * @condition evaluates to true. The @condition is checked each time 247 * the waitqueue @wq is woken up. 248 * 249 * wake_up() has to be called after changing any variable that could 250 * change the result of the wait condition. 251 * 252 * The function returns 0 if the @timeout elapsed, and the remaining 253 * jiffies if the condition evaluated to true before the timeout elapsed. 254 */ 255#define wait_event_timeout(wq, condition, timeout) \ 256({ \ 257 long __ret = timeout; \ 258 if (!(condition)) \ 259 __wait_event_timeout(wq, condition, __ret); \ 260 __ret; \ 261}) 262 263#define __wait_event_interruptible(wq, condition, ret) \ 264do { \ 265 DEFINE_WAIT(__wait); \ 266 \ 267 for (;;) { \ 268 prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE); \ 269 if (condition) \ 270 break; \ 271 if (!signal_pending(current)) { \ 272 schedule(); \ 273 continue; \ 274 } \ 275 ret = -ERESTARTSYS; \ 276 break; \ 277 } \ 278 finish_wait(&wq, &__wait); \ 279} while (0) 280 281/** 282 * wait_event_interruptible - sleep until a condition gets true 283 * @wq: the waitqueue to wait on 284 * @condition: a C expression for the event to wait for 285 * 286 * The process is put to sleep (TASK_INTERRUPTIBLE) until the 287 * @condition evaluates to true or a signal is received. 288 * The @condition is checked each time the waitqueue @wq is woken up. 289 * 290 * wake_up() has to be called after changing any variable that could 291 * change the result of the wait condition. 292 * 293 * The function will return -ERESTARTSYS if it was interrupted by a 294 * signal and 0 if @condition evaluated to true. 295 */ 296#define wait_event_interruptible(wq, condition) \ 297({ \ 298 int __ret = 0; \ 299 if (!(condition)) \ 300 __wait_event_interruptible(wq, condition, __ret); \ 301 __ret; \ 302}) 303 304#define __wait_event_interruptible_timeout(wq, condition, ret) \ 305do { \ 306 DEFINE_WAIT(__wait); \ 307 \ 308 for (;;) { \ 309 prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE); \ 310 if (condition) \ 311 break; \ 312 if (!signal_pending(current)) { \ 313 ret = schedule_timeout(ret); \ 314 if (!ret) \ 315 break; \ 316 continue; \ 317 } \ 318 ret = -ERESTARTSYS; \ 319 break; \ 320 } \ 321 finish_wait(&wq, &__wait); \ 322} while (0) 323 324/** 325 * wait_event_interruptible_timeout - sleep until a condition gets true or a timeout elapses 326 * @wq: the waitqueue to wait on 327 * @condition: a C expression for the event to wait for 328 * @timeout: timeout, in jiffies 329 * 330 * The process is put to sleep (TASK_INTERRUPTIBLE) until the 331 * @condition evaluates to true or a signal is received. 332 * The @condition is checked each time the waitqueue @wq is woken up. 333 * 334 * wake_up() has to be called after changing any variable that could 335 * change the result of the wait condition. 336 * 337 * The function returns 0 if the @timeout elapsed, -ERESTARTSYS if it 338 * was interrupted by a signal, and the remaining jiffies otherwise 339 * if the condition evaluated to true before the timeout elapsed. 340 */ 341#define wait_event_interruptible_timeout(wq, condition, timeout) \ 342({ \ 343 long __ret = timeout; \ 344 if (!(condition)) \ 345 __wait_event_interruptible_timeout(wq, condition, __ret); \ 346 __ret; \ 347}) 348 349#define __wait_event_interruptible_exclusive(wq, condition, ret) \ 350do { \ 351 DEFINE_WAIT(__wait); \ 352 \ 353 for (;;) { \ 354 prepare_to_wait_exclusive(&wq, &__wait, \ 355 TASK_INTERRUPTIBLE); \ 356 if (condition) { \ 357 finish_wait(&wq, &__wait); \ 358 break; \ 359 } \ 360 if (!signal_pending(current)) { \ 361 schedule(); \ 362 continue; \ 363 } \ 364 ret = -ERESTARTSYS; \ 365 abort_exclusive_wait(&wq, &__wait, \ 366 TASK_INTERRUPTIBLE, NULL); \ 367 break; \ 368 } \ 369} while (0) 370 371#define wait_event_interruptible_exclusive(wq, condition) \ 372({ \ 373 int __ret = 0; \ 374 if (!(condition)) \ 375 __wait_event_interruptible_exclusive(wq, condition, __ret);\ 376 __ret; \ 377}) 378 379 380#define __wait_event_interruptible_locked(wq, condition, exclusive, irq) \ 381({ \ 382 int __ret = 0; \ 383 DEFINE_WAIT(__wait); \ 384 if (exclusive) \ 385 __wait.flags |= WQ_FLAG_EXCLUSIVE; \ 386 do { \ 387 if (likely(list_empty(&__wait.task_list))) \ 388 __add_wait_queue_tail(&(wq), &__wait); \ 389 set_current_state(TASK_INTERRUPTIBLE); \ 390 if (signal_pending(current)) { \ 391 __ret = -ERESTARTSYS; \ 392 break; \ 393 } \ 394 if (irq) \ 395 spin_unlock_irq(&(wq).lock); \ 396 else \ 397 spin_unlock(&(wq).lock); \ 398 schedule(); \ 399 if (irq) \ 400 spin_lock_irq(&(wq).lock); \ 401 else \ 402 spin_lock(&(wq).lock); \ 403 } while (!(condition)); \ 404 __remove_wait_queue(&(wq), &__wait); \ 405 __set_current_state(TASK_RUNNING); \ 406 __ret; \ 407}) 408 409 410/** 411 * wait_event_interruptible_locked - sleep until a condition gets true 412 * @wq: the waitqueue to wait on 413 * @condition: a C expression for the event to wait for 414 * 415 * The process is put to sleep (TASK_INTERRUPTIBLE) until the 416 * @condition evaluates to true or a signal is received. 417 * The @condition is checked each time the waitqueue @wq is woken up. 418 * 419 * It must be called with wq.lock being held. This spinlock is 420 * unlocked while sleeping but @condition testing is done while lock 421 * is held and when this macro exits the lock is held. 422 * 423 * The lock is locked/unlocked using spin_lock()/spin_unlock() 424 * functions which must match the way they are locked/unlocked outside 425 * of this macro. 426 * 427 * wake_up_locked() has to be called after changing any variable that could 428 * change the result of the wait condition. 429 * 430 * The function will return -ERESTARTSYS if it was interrupted by a 431 * signal and 0 if @condition evaluated to true. 432 */ 433#define wait_event_interruptible_locked(wq, condition) \ 434 ((condition) \ 435 ? 0 : __wait_event_interruptible_locked(wq, condition, 0, 0)) 436 437/** 438 * wait_event_interruptible_locked_irq - sleep until a condition gets true 439 * @wq: the waitqueue to wait on 440 * @condition: a C expression for the event to wait for 441 * 442 * The process is put to sleep (TASK_INTERRUPTIBLE) until the 443 * @condition evaluates to true or a signal is received. 444 * The @condition is checked each time the waitqueue @wq is woken up. 445 * 446 * It must be called with wq.lock being held. This spinlock is 447 * unlocked while sleeping but @condition testing is done while lock 448 * is held and when this macro exits the lock is held. 449 * 450 * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq() 451 * functions which must match the way they are locked/unlocked outside 452 * of this macro. 453 * 454 * wake_up_locked() has to be called after changing any variable that could 455 * change the result of the wait condition. 456 * 457 * The function will return -ERESTARTSYS if it was interrupted by a 458 * signal and 0 if @condition evaluated to true. 459 */ 460#define wait_event_interruptible_locked_irq(wq, condition) \ 461 ((condition) \ 462 ? 0 : __wait_event_interruptible_locked(wq, condition, 0, 1)) 463 464/** 465 * wait_event_interruptible_exclusive_locked - sleep exclusively until a condition gets true 466 * @wq: the waitqueue to wait on 467 * @condition: a C expression for the event to wait for 468 * 469 * The process is put to sleep (TASK_INTERRUPTIBLE) until the 470 * @condition evaluates to true or a signal is received. 471 * The @condition is checked each time the waitqueue @wq is woken up. 472 * 473 * It must be called with wq.lock being held. This spinlock is 474 * unlocked while sleeping but @condition testing is done while lock 475 * is held and when this macro exits the lock is held. 476 * 477 * The lock is locked/unlocked using spin_lock()/spin_unlock() 478 * functions which must match the way they are locked/unlocked outside 479 * of this macro. 480 * 481 * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag 482 * set thus when other process waits process on the list if this 483 * process is awaken further processes are not considered. 484 * 485 * wake_up_locked() has to be called after changing any variable that could 486 * change the result of the wait condition. 487 * 488 * The function will return -ERESTARTSYS if it was interrupted by a 489 * signal and 0 if @condition evaluated to true. 490 */ 491#define wait_event_interruptible_exclusive_locked(wq, condition) \ 492 ((condition) \ 493 ? 0 : __wait_event_interruptible_locked(wq, condition, 1, 0)) 494 495/** 496 * wait_event_interruptible_exclusive_locked_irq - sleep until a condition gets true 497 * @wq: the waitqueue to wait on 498 * @condition: a C expression for the event to wait for 499 * 500 * The process is put to sleep (TASK_INTERRUPTIBLE) until the 501 * @condition evaluates to true or a signal is received. 502 * The @condition is checked each time the waitqueue @wq is woken up. 503 * 504 * It must be called with wq.lock being held. This spinlock is 505 * unlocked while sleeping but @condition testing is done while lock 506 * is held and when this macro exits the lock is held. 507 * 508 * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq() 509 * functions which must match the way they are locked/unlocked outside 510 * of this macro. 511 * 512 * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag 513 * set thus when other process waits process on the list if this 514 * process is awaken further processes are not considered. 515 * 516 * wake_up_locked() has to be called after changing any variable that could 517 * change the result of the wait condition. 518 * 519 * The function will return -ERESTARTSYS if it was interrupted by a 520 * signal and 0 if @condition evaluated to true. 521 */ 522#define wait_event_interruptible_exclusive_locked_irq(wq, condition) \ 523 ((condition) \ 524 ? 0 : __wait_event_interruptible_locked(wq, condition, 1, 1)) 525 526 527 528#define __wait_event_killable(wq, condition, ret) \ 529do { \ 530 DEFINE_WAIT(__wait); \ 531 \ 532 for (;;) { \ 533 prepare_to_wait(&wq, &__wait, TASK_KILLABLE); \ 534 if (condition) \ 535 break; \ 536 if (!fatal_signal_pending(current)) { \ 537 schedule(); \ 538 continue; \ 539 } \ 540 ret = -ERESTARTSYS; \ 541 break; \ 542 } \ 543 finish_wait(&wq, &__wait); \ 544} while (0) 545 546/** 547 * wait_event_killable - sleep until a condition gets true 548 * @wq: the waitqueue to wait on 549 * @condition: a C expression for the event to wait for 550 * 551 * The process is put to sleep (TASK_KILLABLE) until the 552 * @condition evaluates to true or a signal is received. 553 * The @condition is checked each time the waitqueue @wq is woken up. 554 * 555 * wake_up() 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_killable(wq, condition) \ 562({ \ 563 int __ret = 0; \ 564 if (!(condition)) \ 565 __wait_event_killable(wq, condition, __ret); \ 566 __ret; \ 567}) 568 569/* 570 * These are the old interfaces to sleep waiting for an event. 571 * They are racy. DO NOT use them, use the wait_event* interfaces above. 572 * We plan to remove these interfaces. 573 */ 574extern void sleep_on(wait_queue_head_t *q); 575extern long sleep_on_timeout(wait_queue_head_t *q, 576 signed long timeout); 577extern void interruptible_sleep_on(wait_queue_head_t *q); 578extern long interruptible_sleep_on_timeout(wait_queue_head_t *q, 579 signed long timeout); 580 581/* 582 * Waitqueues which are removed from the waitqueue_head at wakeup time 583 */ 584void prepare_to_wait(wait_queue_head_t *q, wait_queue_t *wait, int state); 585void prepare_to_wait_exclusive(wait_queue_head_t *q, wait_queue_t *wait, int state); 586void finish_wait(wait_queue_head_t *q, wait_queue_t *wait); 587void abort_exclusive_wait(wait_queue_head_t *q, wait_queue_t *wait, 588 unsigned int mode, void *key); 589int autoremove_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key); 590int wake_bit_function(wait_queue_t *wait, unsigned mode, int sync, void *key); 591 592#define DEFINE_WAIT_FUNC(name, function) \ 593 wait_queue_t name = { \ 594 .private = current, \ 595 .func = function, \ 596 .task_list = LIST_HEAD_INIT((name).task_list), \ 597 } 598 599#define DEFINE_WAIT(name) DEFINE_WAIT_FUNC(name, autoremove_wake_function) 600 601#define DEFINE_WAIT_BIT(name, word, bit) \ 602 struct wait_bit_queue name = { \ 603 .key = __WAIT_BIT_KEY_INITIALIZER(word, bit), \ 604 .wait = { \ 605 .private = current, \ 606 .func = wake_bit_function, \ 607 .task_list = \ 608 LIST_HEAD_INIT((name).wait.task_list), \ 609 }, \ 610 } 611 612#define init_wait(wait) \ 613 do { \ 614 (wait)->private = current; \ 615 (wait)->func = autoremove_wake_function; \ 616 INIT_LIST_HEAD(&(wait)->task_list); \ 617 (wait)->flags = 0; \ 618 } while (0) 619 620/** 621 * wait_on_bit - wait for a bit to be cleared 622 * @word: the word being waited on, a kernel virtual address 623 * @bit: the bit of the word being waited on 624 * @action: the function used to sleep, which may take special actions 625 * @mode: the task state to sleep in 626 * 627 * There is a standard hashed waitqueue table for generic use. This 628 * is the part of the hashtable's accessor API that waits on a bit. 629 * For instance, if one were to have waiters on a bitflag, one would 630 * call wait_on_bit() in threads waiting for the bit to clear. 631 * One uses wait_on_bit() where one is waiting for the bit to clear, 632 * but has no intention of setting it. 633 */ 634static inline int wait_on_bit(void *word, int bit, 635 int (*action)(void *), unsigned mode) 636{ 637 if (!test_bit(bit, word)) 638 return 0; 639 return out_of_line_wait_on_bit(word, bit, action, mode); 640} 641 642/** 643 * wait_on_bit_lock - wait for a bit to be cleared, when wanting to set it 644 * @word: the word being waited on, a kernel virtual address 645 * @bit: the bit of the word being waited on 646 * @action: the function used to sleep, which may take special actions 647 * @mode: the task state to sleep in 648 * 649 * There is a standard hashed waitqueue table for generic use. This 650 * is the part of the hashtable's accessor API that waits on a bit 651 * when one intends to set it, for instance, trying to lock bitflags. 652 * For instance, if one were to have waiters trying to set bitflag 653 * and waiting for it to clear before setting it, one would call 654 * wait_on_bit() in threads waiting to be able to set the bit. 655 * One uses wait_on_bit_lock() where one is waiting for the bit to 656 * clear with the intention of setting it, and when done, clearing it. 657 */ 658static inline int wait_on_bit_lock(void *word, int bit, 659 int (*action)(void *), unsigned mode) 660{ 661 if (!test_and_set_bit(bit, word)) 662 return 0; 663 return out_of_line_wait_on_bit_lock(word, bit, action, mode); 664} 665 666#endif /* __KERNEL__ */ 667 668#endif 669