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/system.h> 26#include <asm/current.h> 27 28typedef struct __wait_queue wait_queue_t; 29typedef int (*wait_queue_func_t)(wait_queue_t *wait, unsigned mode, int flags, void *key); 30int default_wake_function(wait_queue_t *wait, unsigned mode, int flags, void *key); 31 32/* __wait_queue::flags */ 33#define WQ_FLAG_EXCLUSIVE 0x01 34#define WQ_FLAG_WOKEN 0x02 35 36struct __wait_queue { 37 unsigned int flags; 38 void *private; 39 wait_queue_func_t func; 40 struct list_head task_list; 41}; 42 43struct wait_bit_key { 44 void *flags; 45 int bit_nr; 46}; 47 48struct wait_bit_queue { 49 struct wait_bit_key key; 50 wait_queue_t wait; 51}; 52 53struct __wait_queue_head { 54 spinlock_t lock; 55 struct list_head task_list; 56}; 57typedef struct __wait_queue_head wait_queue_head_t; 58 59struct task_struct; 60 61/* 62 * Macros for declaration and initialisaton of the datatypes 63 */ 64 65#define __WAITQUEUE_INITIALIZER(name, tsk) { \ 66 .private = tsk, \ 67 .func = default_wake_function, \ 68 .task_list = { NULL, NULL } } 69 70#define DECLARE_WAITQUEUE(name, tsk) \ 71 wait_queue_t name = __WAITQUEUE_INITIALIZER(name, tsk) 72 73#define __WAIT_QUEUE_HEAD_INITIALIZER(name) { \ 74 .lock = __SPIN_LOCK_UNLOCKED(name.lock), \ 75 .task_list = { &(name).task_list, &(name).task_list } } 76 77#define DECLARE_WAIT_QUEUE_HEAD(name) \ 78 wait_queue_head_t name = __WAIT_QUEUE_HEAD_INITIALIZER(name) 79 80#define __WAIT_BIT_KEY_INITIALIZER(word, bit) \ 81 { .flags = word, .bit_nr = bit, } 82 83extern void __init_waitqueue_head(wait_queue_head_t *q, struct lock_class_key *); 84 85#define init_waitqueue_head(q) \ 86 do { \ 87 static struct lock_class_key __key; \ 88 \ 89 __init_waitqueue_head((q), &__key); \ 90 } while (0) 91 92#ifdef CONFIG_LOCKDEP 93# define __WAIT_QUEUE_HEAD_INIT_ONSTACK(name) \ 94 ({ init_waitqueue_head(&name); name; }) 95# define DECLARE_WAIT_QUEUE_HEAD_ONSTACK(name) \ 96 wait_queue_head_t name = __WAIT_QUEUE_HEAD_INIT_ONSTACK(name) 97#else 98# define DECLARE_WAIT_QUEUE_HEAD_ONSTACK(name) DECLARE_WAIT_QUEUE_HEAD(name) 99#endif 100 101static inline void init_waitqueue_entry(wait_queue_t *q, struct task_struct *p) 102{ 103 q->flags = 0; 104 q->private = p; 105 q->func = default_wake_function; 106} 107 108static inline void init_waitqueue_func_entry(wait_queue_t *q, 109 wait_queue_func_t func) 110{ 111 q->flags = 0; 112 q->private = NULL; 113 q->func = func; 114} 115 116static inline int waitqueue_active(wait_queue_head_t *q) 117{ 118 return !list_empty(&q->task_list); 119} 120 121extern void add_wait_queue(wait_queue_head_t *q, wait_queue_t *wait); 122extern void add_wait_queue_exclusive(wait_queue_head_t *q, wait_queue_t *wait); 123extern void remove_wait_queue(wait_queue_head_t *q, wait_queue_t *wait); 124 125static inline void __add_wait_queue(wait_queue_head_t *head, wait_queue_t *new) 126{ 127 list_add(&new->task_list, &head->task_list); 128} 129 130/* 131 * Used for wake-one threads: 132 */ 133static inline void __add_wait_queue_exclusive(wait_queue_head_t *q, 134 wait_queue_t *wait) 135{ 136 wait->flags |= WQ_FLAG_EXCLUSIVE; 137 __add_wait_queue(q, wait); 138} 139 140static inline void __add_wait_queue_tail(wait_queue_head_t *head, 141 wait_queue_t *new) 142{ 143 list_add_tail(&new->task_list, &head->task_list); 144} 145 146static inline void __add_wait_queue_tail_exclusive(wait_queue_head_t *q, 147 wait_queue_t *wait) 148{ 149 wait->flags |= WQ_FLAG_EXCLUSIVE; 150 __add_wait_queue_tail(q, wait); 151} 152 153static inline void __remove_wait_queue(wait_queue_head_t *head, 154 wait_queue_t *old) 155{ 156 list_del(&old->task_list); 157} 158 159void __wake_up(wait_queue_head_t *q, unsigned int mode, int nr, void *key); 160void __wake_up_locked_key(wait_queue_head_t *q, unsigned int mode, void *key); 161void __wake_up_sync_key(wait_queue_head_t *q, unsigned int mode, int nr, 162 void *key); 163void __wake_up_locked(wait_queue_head_t *q, unsigned int mode); 164void __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr); 165void __wake_up_bit(wait_queue_head_t *, void *, int); 166int __wait_on_bit(wait_queue_head_t *, struct wait_bit_queue *, int (*)(void *), unsigned); 167int __wait_on_bit_lock(wait_queue_head_t *, struct wait_bit_queue *, int (*)(void *), unsigned); 168void wake_up_bit(void *, int); 169int out_of_line_wait_on_bit(void *, int, int (*)(void *), unsigned); 170int out_of_line_wait_on_bit_lock(void *, int, int (*)(void *), unsigned); 171wait_queue_head_t *bit_waitqueue(void *, int); 172 173#define wake_up(x) __wake_up(x, TASK_NORMAL, 1, NULL) 174#define wake_up_nr(x, nr) __wake_up(x, TASK_NORMAL, nr, NULL) 175#define wake_up_all(x) __wake_up(x, TASK_NORMAL, 0, NULL) 176#define wake_up_locked(x) __wake_up_locked((x), TASK_NORMAL) 177 178#define wake_up_interruptible(x) __wake_up(x, TASK_INTERRUPTIBLE, 1, NULL) 179#define wake_up_interruptible_nr(x, nr) __wake_up(x, TASK_INTERRUPTIBLE, nr, NULL) 180#define wake_up_interruptible_all(x) __wake_up(x, TASK_INTERRUPTIBLE, 0, NULL) 181#define wake_up_interruptible_sync(x) __wake_up_sync((x), TASK_INTERRUPTIBLE, 1) 182 183/* 184 * Wakeup macros to be used to report events to the targets. 185 */ 186#define wake_up_poll(x, m) \ 187 __wake_up(x, TASK_NORMAL, 1, (void *) (m)) 188#define wake_up_locked_poll(x, m) \ 189 __wake_up_locked_key((x), TASK_NORMAL, (void *) (m)) 190#define wake_up_interruptible_poll(x, m) \ 191 __wake_up(x, TASK_INTERRUPTIBLE, 1, (void *) (m)) 192#define wake_up_interruptible_sync_poll(x, m) \ 193 __wake_up_sync_key((x), TASK_INTERRUPTIBLE, 1, (void *) (m)) 194 195#define __wait_event(wq, condition) \ 196do { \ 197 DEFINE_WAIT(__wait); \ 198 \ 199 for (;;) { \ 200 prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE); \ 201 if (condition) \ 202 break; \ 203 schedule(); \ 204 } \ 205 finish_wait(&wq, &__wait); \ 206} while (0) 207 208/** 209 * wait_event - sleep until a condition gets true 210 * @wq: the waitqueue to wait on 211 * @condition: a C expression for the event to wait for 212 * 213 * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the 214 * @condition evaluates to true. The @condition is checked each time 215 * the waitqueue @wq is woken up. 216 * 217 * wake_up() has to be called after changing any variable that could 218 * change the result of the wait condition. 219 */ 220#define wait_event(wq, condition) \ 221do { \ 222 if (condition) \ 223 break; \ 224 __wait_event(wq, condition); \ 225} while (0) 226 227#define __wait_event_timeout(wq, condition, ret) \ 228do { \ 229 DEFINE_WAIT(__wait); \ 230 \ 231 for (;;) { \ 232 prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE); \ 233 if (condition) \ 234 break; \ 235 ret = schedule_timeout(ret); \ 236 if (!ret) \ 237 break; \ 238 } \ 239 finish_wait(&wq, &__wait); \ 240} while (0) 241 242/** 243 * wait_event_timeout - sleep until a condition gets true or a timeout elapses 244 * @wq: the waitqueue to wait on 245 * @condition: a C expression for the event to wait for 246 * @timeout: timeout, in jiffies 247 * 248 * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the 249 * @condition evaluates to true. The @condition is checked each time 250 * the waitqueue @wq is woken up. 251 * 252 * wake_up() has to be called after changing any variable that could 253 * change the result of the wait condition. 254 * 255 * The function returns 0 if the @timeout elapsed, and the remaining 256 * jiffies if the condition evaluated to true before the timeout elapsed. 257 */ 258#define wait_event_timeout(wq, condition, timeout) \ 259({ \ 260 long __ret = timeout; \ 261 if (!(condition)) \ 262 __wait_event_timeout(wq, condition, __ret); \ 263 __ret; \ 264}) 265 266#define __wait_event_interruptible(wq, condition, ret) \ 267do { \ 268 DEFINE_WAIT(__wait); \ 269 \ 270 for (;;) { \ 271 prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE); \ 272 if (condition) \ 273 break; \ 274 if (!signal_pending(current)) { \ 275 schedule(); \ 276 continue; \ 277 } \ 278 ret = -ERESTARTSYS; \ 279 break; \ 280 } \ 281 finish_wait(&wq, &__wait); \ 282} while (0) 283 284/** 285 * wait_event_interruptible - sleep until a condition gets true 286 * @wq: the waitqueue to wait on 287 * @condition: a C expression for the event to wait for 288 * 289 * The process is put to sleep (TASK_INTERRUPTIBLE) until the 290 * @condition evaluates to true or a signal is received. 291 * The @condition is checked each time the waitqueue @wq is woken up. 292 * 293 * wake_up() has to be called after changing any variable that could 294 * change the result of the wait condition. 295 * 296 * The function will return -ERESTARTSYS if it was interrupted by a 297 * signal and 0 if @condition evaluated to true. 298 */ 299#define wait_event_interruptible(wq, condition) \ 300({ \ 301 int __ret = 0; \ 302 if (!(condition)) \ 303 __wait_event_interruptible(wq, condition, __ret); \ 304 __ret; \ 305}) 306 307#define __wait_event_interruptible_timeout(wq, condition, ret) \ 308do { \ 309 DEFINE_WAIT(__wait); \ 310 \ 311 for (;;) { \ 312 prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE); \ 313 if (condition) \ 314 break; \ 315 if (!signal_pending(current)) { \ 316 ret = schedule_timeout(ret); \ 317 if (!ret) \ 318 break; \ 319 continue; \ 320 } \ 321 ret = -ERESTARTSYS; \ 322 break; \ 323 } \ 324 finish_wait(&wq, &__wait); \ 325} while (0) 326 327/** 328 * wait_event_interruptible_timeout - sleep until a condition gets true or a timeout elapses 329 * @wq: the waitqueue to wait on 330 * @condition: a C expression for the event to wait for 331 * @timeout: timeout, in jiffies 332 * 333 * The process is put to sleep (TASK_INTERRUPTIBLE) until the 334 * @condition evaluates to true or a signal is received. 335 * The @condition is checked each time the waitqueue @wq is woken up. 336 * 337 * wake_up() has to be called after changing any variable that could 338 * change the result of the wait condition. 339 * 340 * The function returns 0 if the @timeout elapsed, -ERESTARTSYS if it 341 * was interrupted by a signal, and the remaining jiffies otherwise 342 * if the condition evaluated to true before the timeout elapsed. 343 */ 344#define wait_event_interruptible_timeout(wq, condition, timeout) \ 345({ \ 346 long __ret = timeout; \ 347 if (!(condition)) \ 348 __wait_event_interruptible_timeout(wq, condition, __ret); \ 349 __ret; \ 350}) 351 352#define __wait_event_interruptible_exclusive(wq, condition, ret) \ 353do { \ 354 DEFINE_WAIT(__wait); \ 355 \ 356 for (;;) { \ 357 prepare_to_wait_exclusive(&wq, &__wait, \ 358 TASK_INTERRUPTIBLE); \ 359 if (condition) { \ 360 finish_wait(&wq, &__wait); \ 361 break; \ 362 } \ 363 if (!signal_pending(current)) { \ 364 schedule(); \ 365 continue; \ 366 } \ 367 ret = -ERESTARTSYS; \ 368 abort_exclusive_wait(&wq, &__wait, \ 369 TASK_INTERRUPTIBLE, NULL); \ 370 break; \ 371 } \ 372} while (0) 373 374#define wait_event_interruptible_exclusive(wq, condition) \ 375({ \ 376 int __ret = 0; \ 377 if (!(condition)) \ 378 __wait_event_interruptible_exclusive(wq, condition, __ret);\ 379 __ret; \ 380}) 381 382 383#define __wait_event_interruptible_locked(wq, condition, exclusive, irq) \ 384({ \ 385 int __ret = 0; \ 386 DEFINE_WAIT(__wait); \ 387 if (exclusive) \ 388 __wait.flags |= WQ_FLAG_EXCLUSIVE; \ 389 do { \ 390 if (likely(list_empty(&__wait.task_list))) \ 391 __add_wait_queue_tail(&(wq), &__wait); \ 392 set_current_state(TASK_INTERRUPTIBLE); \ 393 if (signal_pending(current)) { \ 394 __ret = -ERESTARTSYS; \ 395 break; \ 396 } \ 397 if (irq) \ 398 spin_unlock_irq(&(wq).lock); \ 399 else \ 400 spin_unlock(&(wq).lock); \ 401 schedule(); \ 402 if (irq) \ 403 spin_lock_irq(&(wq).lock); \ 404 else \ 405 spin_lock(&(wq).lock); \ 406 } while (!(condition)); \ 407 __remove_wait_queue(&(wq), &__wait); \ 408 __set_current_state(TASK_RUNNING); \ 409 __ret; \ 410}) 411 412 413/** 414 * wait_event_interruptible_locked - sleep until a condition gets true 415 * @wq: the waitqueue to wait on 416 * @condition: a C expression for the event to wait for 417 * 418 * The process is put to sleep (TASK_INTERRUPTIBLE) until the 419 * @condition evaluates to true or a signal is received. 420 * The @condition is checked each time the waitqueue @wq is woken up. 421 * 422 * It must be called with wq.lock being held. This spinlock is 423 * unlocked while sleeping but @condition testing is done while lock 424 * is held and when this macro exits the lock is held. 425 * 426 * The lock is locked/unlocked using spin_lock()/spin_unlock() 427 * functions which must match the way they are locked/unlocked outside 428 * of this macro. 429 * 430 * wake_up_locked() has to be called after changing any variable that could 431 * change the result of the wait condition. 432 * 433 * The function will return -ERESTARTSYS if it was interrupted by a 434 * signal and 0 if @condition evaluated to true. 435 */ 436#define wait_event_interruptible_locked(wq, condition) \ 437 ((condition) \ 438 ? 0 : __wait_event_interruptible_locked(wq, condition, 0, 0)) 439 440/** 441 * wait_event_interruptible_locked_irq - sleep until a condition gets true 442 * @wq: the waitqueue to wait on 443 * @condition: a C expression for the event to wait for 444 * 445 * The process is put to sleep (TASK_INTERRUPTIBLE) until the 446 * @condition evaluates to true or a signal is received. 447 * The @condition is checked each time the waitqueue @wq is woken up. 448 * 449 * It must be called with wq.lock being held. This spinlock is 450 * unlocked while sleeping but @condition testing is done while lock 451 * is held and when this macro exits the lock is held. 452 * 453 * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq() 454 * functions which must match the way they are locked/unlocked outside 455 * of this macro. 456 * 457 * wake_up_locked() has to be called after changing any variable that could 458 * change the result of the wait condition. 459 * 460 * The function will return -ERESTARTSYS if it was interrupted by a 461 * signal and 0 if @condition evaluated to true. 462 */ 463#define wait_event_interruptible_locked_irq(wq, condition) \ 464 ((condition) \ 465 ? 0 : __wait_event_interruptible_locked(wq, condition, 0, 1)) 466 467/** 468 * wait_event_interruptible_exclusive_locked - sleep exclusively until a condition gets true 469 * @wq: the waitqueue to wait on 470 * @condition: a C expression for the event to wait for 471 * 472 * The process is put to sleep (TASK_INTERRUPTIBLE) until the 473 * @condition evaluates to true or a signal is received. 474 * The @condition is checked each time the waitqueue @wq is woken up. 475 * 476 * It must be called with wq.lock being held. This spinlock is 477 * unlocked while sleeping but @condition testing is done while lock 478 * is held and when this macro exits the lock is held. 479 * 480 * The lock is locked/unlocked using spin_lock()/spin_unlock() 481 * functions which must match the way they are locked/unlocked outside 482 * of this macro. 483 * 484 * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag 485 * set thus when other process waits process on the list if this 486 * process is awaken further processes are not considered. 487 * 488 * wake_up_locked() has to be called after changing any variable that could 489 * change the result of the wait condition. 490 * 491 * The function will return -ERESTARTSYS if it was interrupted by a 492 * signal and 0 if @condition evaluated to true. 493 */ 494#define wait_event_interruptible_exclusive_locked(wq, condition) \ 495 ((condition) \ 496 ? 0 : __wait_event_interruptible_locked(wq, condition, 1, 0)) 497 498/** 499 * wait_event_interruptible_exclusive_locked_irq - sleep until a condition gets true 500 * @wq: the waitqueue to wait on 501 * @condition: a C expression for the event to wait for 502 * 503 * The process is put to sleep (TASK_INTERRUPTIBLE) until the 504 * @condition evaluates to true or a signal is received. 505 * The @condition is checked each time the waitqueue @wq is woken up. 506 * 507 * It must be called with wq.lock being held. This spinlock is 508 * unlocked while sleeping but @condition testing is done while lock 509 * is held and when this macro exits the lock is held. 510 * 511 * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq() 512 * functions which must match the way they are locked/unlocked outside 513 * of this macro. 514 * 515 * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag 516 * set thus when other process waits process on the list if this 517 * process is awaken further processes are not considered. 518 * 519 * wake_up_locked() has to be called after changing any variable that could 520 * change the result of the wait condition. 521 * 522 * The function will return -ERESTARTSYS if it was interrupted by a 523 * signal and 0 if @condition evaluated to true. 524 */ 525#define wait_event_interruptible_exclusive_locked_irq(wq, condition) \ 526 ((condition) \ 527 ? 0 : __wait_event_interruptible_locked(wq, condition, 1, 1)) 528 529 530 531#define __wait_event_killable(wq, condition, ret) \ 532do { \ 533 DEFINE_WAIT(__wait); \ 534 \ 535 for (;;) { \ 536 prepare_to_wait(&wq, &__wait, TASK_KILLABLE); \ 537 if (condition) \ 538 break; \ 539 if (!fatal_signal_pending(current)) { \ 540 schedule(); \ 541 continue; \ 542 } \ 543 ret = -ERESTARTSYS; \ 544 break; \ 545 } \ 546 finish_wait(&wq, &__wait); \ 547} while (0) 548 549/** 550 * wait_event_killable - sleep until a condition gets true 551 * @wq: the waitqueue to wait on 552 * @condition: a C expression for the event to wait for 553 * 554 * The process is put to sleep (TASK_KILLABLE) until the 555 * @condition evaluates to true or a signal is received. 556 * The @condition is checked each time the waitqueue @wq is woken up. 557 * 558 * wake_up() has to be called after changing any variable that could 559 * change the result of the wait condition. 560 * 561 * The function will return -ERESTARTSYS if it was interrupted by a 562 * signal and 0 if @condition evaluated to true. 563 */ 564#define wait_event_killable(wq, condition) \ 565({ \ 566 int __ret = 0; \ 567 if (!(condition)) \ 568 __wait_event_killable(wq, condition, __ret); \ 569 __ret; \ 570}) 571 572/* 573 * These are the old interfaces to sleep waiting for an event. 574 * They are racy. DO NOT use them, use the wait_event* interfaces above. 575 * We plan to remove these interfaces. 576 */ 577extern void sleep_on(wait_queue_head_t *q); 578extern long sleep_on_timeout(wait_queue_head_t *q, 579 signed long timeout); 580extern void interruptible_sleep_on(wait_queue_head_t *q); 581extern long interruptible_sleep_on_timeout(wait_queue_head_t *q, 582 signed long timeout); 583 584/* 585 * Waitqueues which are removed from the waitqueue_head at wakeup time 586 */ 587void prepare_to_wait(wait_queue_head_t *q, wait_queue_t *wait, int state); 588void prepare_to_wait_exclusive(wait_queue_head_t *q, wait_queue_t *wait, int state); 589void finish_wait(wait_queue_head_t *q, wait_queue_t *wait); 590void abort_exclusive_wait(wait_queue_head_t *q, wait_queue_t *wait, 591 unsigned int mode, void *key); 592int autoremove_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key); 593long wait_woken(wait_queue_t *wait, unsigned mode, long timeout); 594int woken_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key); 595int wake_bit_function(wait_queue_t *wait, unsigned mode, int sync, void *key); 596 597#define DEFINE_WAIT_FUNC(name, function) \ 598 wait_queue_t name = { \ 599 .private = current, \ 600 .func = function, \ 601 .task_list = LIST_HEAD_INIT((name).task_list), \ 602 } 603 604#define DEFINE_WAIT(name) DEFINE_WAIT_FUNC(name, autoremove_wake_function) 605 606#define DEFINE_WAIT_BIT(name, word, bit) \ 607 struct wait_bit_queue name = { \ 608 .key = __WAIT_BIT_KEY_INITIALIZER(word, bit), \ 609 .wait = { \ 610 .private = current, \ 611 .func = wake_bit_function, \ 612 .task_list = \ 613 LIST_HEAD_INIT((name).wait.task_list), \ 614 }, \ 615 } 616 617#define init_wait(wait) \ 618 do { \ 619 (wait)->private = current; \ 620 (wait)->func = autoremove_wake_function; \ 621 INIT_LIST_HEAD(&(wait)->task_list); \ 622 (wait)->flags = 0; \ 623 } while (0) 624 625/** 626 * wait_on_bit - wait for a bit to be cleared 627 * @word: the word being waited on, a kernel virtual address 628 * @bit: the bit of the word being waited on 629 * @action: the function used to sleep, which may take special actions 630 * @mode: the task state to sleep in 631 * 632 * There is a standard hashed waitqueue table for generic use. This 633 * is the part of the hashtable's accessor API that waits on a bit. 634 * For instance, if one were to have waiters on a bitflag, one would 635 * call wait_on_bit() in threads waiting for the bit to clear. 636 * One uses wait_on_bit() where one is waiting for the bit to clear, 637 * but has no intention of setting it. 638 */ 639static inline int wait_on_bit(void *word, int bit, 640 int (*action)(void *), unsigned mode) 641{ 642 if (!test_bit(bit, word)) 643 return 0; 644 return out_of_line_wait_on_bit(word, bit, action, mode); 645} 646 647/** 648 * wait_on_bit_lock - wait for a bit to be cleared, when wanting to set it 649 * @word: the word being waited on, a kernel virtual address 650 * @bit: the bit of the word being waited on 651 * @action: the function used to sleep, which may take special actions 652 * @mode: the task state to sleep in 653 * 654 * There is a standard hashed waitqueue table for generic use. This 655 * is the part of the hashtable's accessor API that waits on a bit 656 * when one intends to set it, for instance, trying to lock bitflags. 657 * For instance, if one were to have waiters trying to set bitflag 658 * and waiting for it to clear before setting it, one would call 659 * wait_on_bit() in threads waiting to be able to set the bit. 660 * One uses wait_on_bit_lock() where one is waiting for the bit to 661 * clear with the intention of setting it, and when done, clearing it. 662 */ 663static inline int wait_on_bit_lock(void *word, int bit, 664 int (*action)(void *), unsigned mode) 665{ 666 if (!test_and_set_bit(bit, word)) 667 return 0; 668 return out_of_line_wait_on_bit_lock(word, bit, action, mode); 669} 670 671#endif /* __KERNEL__ */ 672 673#endif 674