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6053ee3b IM |
1 | /* |
2 | * Mutexes: blocking mutual exclusion locks | |
3 | * | |
4 | * started by Ingo Molnar: | |
5 | * | |
6 | * Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> | |
7 | * | |
8 | * This file contains the main data structure and API definitions. | |
9 | */ | |
10 | #ifndef __LINUX_MUTEX_H | |
11 | #define __LINUX_MUTEX_H | |
12 | ||
040a0a37 | 13 | #include <asm/current.h> |
6053ee3b IM |
14 | #include <linux/list.h> |
15 | #include <linux/spinlock_types.h> | |
a8b9ee73 | 16 | #include <linux/linkage.h> |
ef5d4707 | 17 | #include <linux/lockdep.h> |
6053ee3b | 18 | |
60063497 | 19 | #include <linux/atomic.h> |
6053ee3b IM |
20 | |
21 | /* | |
22 | * Simple, straightforward mutexes with strict semantics: | |
23 | * | |
24 | * - only one task can hold the mutex at a time | |
25 | * - only the owner can unlock the mutex | |
26 | * - multiple unlocks are not permitted | |
27 | * - recursive locking is not permitted | |
28 | * - a mutex object must be initialized via the API | |
29 | * - a mutex object must not be initialized via memset or copying | |
30 | * - task may not exit with mutex held | |
31 | * - memory areas where held locks reside must not be freed | |
32 | * - held mutexes must not be reinitialized | |
f20fda48 ML |
33 | * - mutexes may not be used in hardware or software interrupt |
34 | * contexts such as tasklets and timers | |
6053ee3b IM |
35 | * |
36 | * These semantics are fully enforced when DEBUG_MUTEXES is | |
37 | * enabled. Furthermore, besides enforcing the above rules, the mutex | |
38 | * debugging code also implements a number of additional features | |
39 | * that make lock debugging easier and faster: | |
40 | * | |
41 | * - uses symbolic names of mutexes, whenever they are printed in debug output | |
42 | * - point-of-acquire tracking, symbolic lookup of function names | |
43 | * - list of all locks held in the system, printout of them | |
44 | * - owner tracking | |
45 | * - detects self-recursing locks and prints out all relevant info | |
46 | * - detects multi-task circular deadlocks and prints out all affected | |
47 | * locks and tasks (and only those tasks) | |
48 | */ | |
49 | struct mutex { | |
50 | /* 1: unlocked, 0: locked, negative: locked, possible waiters */ | |
51 | atomic_t count; | |
52 | spinlock_t wait_lock; | |
53 | struct list_head wait_list; | |
0d66bf6d | 54 | #if defined(CONFIG_DEBUG_MUTEXES) || defined(CONFIG_SMP) |
c6eb3dda | 55 | struct task_struct *owner; |
0d66bf6d | 56 | #endif |
2bd2c92c WL |
57 | #ifdef CONFIG_MUTEX_SPIN_ON_OWNER |
58 | void *spin_mlock; /* Spinner MCS lock */ | |
59 | #endif | |
0d66bf6d | 60 | #ifdef CONFIG_DEBUG_MUTEXES |
6053ee3b IM |
61 | const char *name; |
62 | void *magic; | |
63 | #endif | |
ef5d4707 IM |
64 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
65 | struct lockdep_map dep_map; | |
66 | #endif | |
6053ee3b IM |
67 | }; |
68 | ||
69 | /* | |
70 | * This is the control structure for tasks blocked on mutex, | |
71 | * which resides on the blocked task's kernel stack: | |
72 | */ | |
73 | struct mutex_waiter { | |
74 | struct list_head list; | |
75 | struct task_struct *task; | |
76 | #ifdef CONFIG_DEBUG_MUTEXES | |
6053ee3b IM |
77 | void *magic; |
78 | #endif | |
79 | }; | |
80 | ||
040a0a37 ML |
81 | struct ww_class { |
82 | atomic_long_t stamp; | |
83 | struct lock_class_key acquire_key; | |
84 | struct lock_class_key mutex_key; | |
85 | const char *acquire_name; | |
86 | const char *mutex_name; | |
87 | }; | |
88 | ||
89 | struct ww_acquire_ctx { | |
90 | struct task_struct *task; | |
91 | unsigned long stamp; | |
92 | unsigned acquired; | |
93 | #ifdef CONFIG_DEBUG_MUTEXES | |
94 | unsigned done_acquire; | |
95 | struct ww_class *ww_class; | |
96 | struct ww_mutex *contending_lock; | |
97 | #endif | |
98 | #ifdef CONFIG_DEBUG_LOCK_ALLOC | |
99 | struct lockdep_map dep_map; | |
100 | #endif | |
23010027 DV |
101 | #ifdef CONFIG_DEBUG_WW_MUTEX_SLOWPATH |
102 | unsigned deadlock_inject_interval; | |
103 | unsigned deadlock_inject_countdown; | |
104 | #endif | |
040a0a37 ML |
105 | }; |
106 | ||
107 | struct ww_mutex { | |
108 | struct mutex base; | |
109 | struct ww_acquire_ctx *ctx; | |
110 | #ifdef CONFIG_DEBUG_MUTEXES | |
111 | struct ww_class *ww_class; | |
112 | #endif | |
113 | }; | |
114 | ||
6053ee3b IM |
115 | #ifdef CONFIG_DEBUG_MUTEXES |
116 | # include <linux/mutex-debug.h> | |
117 | #else | |
118 | # define __DEBUG_MUTEX_INITIALIZER(lockname) | |
ef5dc121 RD |
119 | /** |
120 | * mutex_init - initialize the mutex | |
121 | * @mutex: the mutex to be initialized | |
122 | * | |
123 | * Initialize the mutex to unlocked state. | |
124 | * | |
125 | * It is not allowed to initialize an already locked mutex. | |
126 | */ | |
ef5d4707 IM |
127 | # define mutex_init(mutex) \ |
128 | do { \ | |
129 | static struct lock_class_key __key; \ | |
130 | \ | |
131 | __mutex_init((mutex), #mutex, &__key); \ | |
132 | } while (0) | |
4582c0a4 | 133 | static inline void mutex_destroy(struct mutex *lock) {} |
6053ee3b IM |
134 | #endif |
135 | ||
ef5d4707 IM |
136 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
137 | # define __DEP_MAP_MUTEX_INITIALIZER(lockname) \ | |
138 | , .dep_map = { .name = #lockname } | |
040a0a37 ML |
139 | # define __WW_CLASS_MUTEX_INITIALIZER(lockname, ww_class) \ |
140 | , .ww_class = &ww_class | |
ef5d4707 IM |
141 | #else |
142 | # define __DEP_MAP_MUTEX_INITIALIZER(lockname) | |
040a0a37 | 143 | # define __WW_CLASS_MUTEX_INITIALIZER(lockname, ww_class) |
ef5d4707 IM |
144 | #endif |
145 | ||
6053ee3b IM |
146 | #define __MUTEX_INITIALIZER(lockname) \ |
147 | { .count = ATOMIC_INIT(1) \ | |
6cfd76a2 | 148 | , .wait_lock = __SPIN_LOCK_UNLOCKED(lockname.wait_lock) \ |
6053ee3b | 149 | , .wait_list = LIST_HEAD_INIT(lockname.wait_list) \ |
ef5d4707 IM |
150 | __DEBUG_MUTEX_INITIALIZER(lockname) \ |
151 | __DEP_MAP_MUTEX_INITIALIZER(lockname) } | |
6053ee3b | 152 | |
040a0a37 ML |
153 | #define __WW_CLASS_INITIALIZER(ww_class) \ |
154 | { .stamp = ATOMIC_LONG_INIT(0) \ | |
155 | , .acquire_name = #ww_class "_acquire" \ | |
156 | , .mutex_name = #ww_class "_mutex" } | |
157 | ||
158 | #define __WW_MUTEX_INITIALIZER(lockname, class) \ | |
159 | { .base = { \__MUTEX_INITIALIZER(lockname) } \ | |
160 | __WW_CLASS_MUTEX_INITIALIZER(lockname, class) } | |
161 | ||
6053ee3b IM |
162 | #define DEFINE_MUTEX(mutexname) \ |
163 | struct mutex mutexname = __MUTEX_INITIALIZER(mutexname) | |
164 | ||
040a0a37 ML |
165 | #define DEFINE_WW_CLASS(classname) \ |
166 | struct ww_class classname = __WW_CLASS_INITIALIZER(classname) | |
167 | ||
168 | #define DEFINE_WW_MUTEX(mutexname, ww_class) \ | |
169 | struct ww_mutex mutexname = __WW_MUTEX_INITIALIZER(mutexname, ww_class) | |
170 | ||
171 | ||
ef5d4707 IM |
172 | extern void __mutex_init(struct mutex *lock, const char *name, |
173 | struct lock_class_key *key); | |
6053ee3b | 174 | |
040a0a37 ML |
175 | /** |
176 | * ww_mutex_init - initialize the w/w mutex | |
177 | * @lock: the mutex to be initialized | |
178 | * @ww_class: the w/w class the mutex should belong to | |
179 | * | |
180 | * Initialize the w/w mutex to unlocked state and associate it with the given | |
181 | * class. | |
182 | * | |
183 | * It is not allowed to initialize an already locked mutex. | |
184 | */ | |
185 | static inline void ww_mutex_init(struct ww_mutex *lock, | |
186 | struct ww_class *ww_class) | |
187 | { | |
188 | __mutex_init(&lock->base, ww_class->mutex_name, &ww_class->mutex_key); | |
189 | lock->ctx = NULL; | |
190 | #ifdef CONFIG_DEBUG_MUTEXES | |
191 | lock->ww_class = ww_class; | |
192 | #endif | |
193 | } | |
194 | ||
45f8bde0 | 195 | /** |
6053ee3b IM |
196 | * mutex_is_locked - is the mutex locked |
197 | * @lock: the mutex to be queried | |
198 | * | |
199 | * Returns 1 if the mutex is locked, 0 if unlocked. | |
200 | */ | |
ec701584 | 201 | static inline int mutex_is_locked(struct mutex *lock) |
6053ee3b IM |
202 | { |
203 | return atomic_read(&lock->count) != 1; | |
204 | } | |
205 | ||
206 | /* | |
207 | * See kernel/mutex.c for detailed documentation of these APIs. | |
208 | * Also see Documentation/mutex-design.txt. | |
209 | */ | |
ef5d4707 IM |
210 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
211 | extern void mutex_lock_nested(struct mutex *lock, unsigned int subclass); | |
e4c70a66 | 212 | extern void _mutex_lock_nest_lock(struct mutex *lock, struct lockdep_map *nest_lock); |
040a0a37 | 213 | |
18d8362d AM |
214 | extern int __must_check mutex_lock_interruptible_nested(struct mutex *lock, |
215 | unsigned int subclass); | |
ad776537 LH |
216 | extern int __must_check mutex_lock_killable_nested(struct mutex *lock, |
217 | unsigned int subclass); | |
e4564f79 PZ |
218 | |
219 | #define mutex_lock(lock) mutex_lock_nested(lock, 0) | |
220 | #define mutex_lock_interruptible(lock) mutex_lock_interruptible_nested(lock, 0) | |
ad776537 | 221 | #define mutex_lock_killable(lock) mutex_lock_killable_nested(lock, 0) |
e4c70a66 PZ |
222 | |
223 | #define mutex_lock_nest_lock(lock, nest_lock) \ | |
224 | do { \ | |
040a0a37 | 225 | typecheck(struct lockdep_map *, &(nest_lock)->dep_map); \ |
e4c70a66 PZ |
226 | _mutex_lock_nest_lock(lock, &(nest_lock)->dep_map); \ |
227 | } while (0) | |
228 | ||
ef5d4707 | 229 | #else |
ec701584 HH |
230 | extern void mutex_lock(struct mutex *lock); |
231 | extern int __must_check mutex_lock_interruptible(struct mutex *lock); | |
232 | extern int __must_check mutex_lock_killable(struct mutex *lock); | |
e4564f79 | 233 | |
ef5d4707 | 234 | # define mutex_lock_nested(lock, subclass) mutex_lock(lock) |
d63a5a74 | 235 | # define mutex_lock_interruptible_nested(lock, subclass) mutex_lock_interruptible(lock) |
ad776537 | 236 | # define mutex_lock_killable_nested(lock, subclass) mutex_lock_killable(lock) |
e4c70a66 | 237 | # define mutex_lock_nest_lock(lock, nest_lock) mutex_lock(lock) |
ef5d4707 IM |
238 | #endif |
239 | ||
6053ee3b IM |
240 | /* |
241 | * NOTE: mutex_trylock() follows the spin_trylock() convention, | |
242 | * not the down_trylock() convention! | |
d98d38f2 AV |
243 | * |
244 | * Returns 1 if the mutex has been acquired successfully, and 0 on contention. | |
6053ee3b | 245 | */ |
ec701584 HH |
246 | extern int mutex_trylock(struct mutex *lock); |
247 | extern void mutex_unlock(struct mutex *lock); | |
040a0a37 ML |
248 | |
249 | /** | |
250 | * ww_acquire_init - initialize a w/w acquire context | |
251 | * @ctx: w/w acquire context to initialize | |
252 | * @ww_class: w/w class of the context | |
253 | * | |
254 | * Initializes an context to acquire multiple mutexes of the given w/w class. | |
255 | * | |
256 | * Context-based w/w mutex acquiring can be done in any order whatsoever within | |
257 | * a given lock class. Deadlocks will be detected and handled with the | |
258 | * wait/wound logic. | |
259 | * | |
260 | * Mixing of context-based w/w mutex acquiring and single w/w mutex locking can | |
261 | * result in undetected deadlocks and is so forbidden. Mixing different contexts | |
262 | * for the same w/w class when acquiring mutexes can also result in undetected | |
263 | * deadlocks, and is hence also forbidden. Both types of abuse will be caught by | |
264 | * enabling CONFIG_PROVE_LOCKING. | |
265 | * | |
266 | * Nesting of acquire contexts for _different_ w/w classes is possible, subject | |
267 | * to the usual locking rules between different lock classes. | |
268 | * | |
269 | * An acquire context must be released with ww_acquire_fini by the same task | |
270 | * before the memory is freed. It is recommended to allocate the context itself | |
271 | * on the stack. | |
272 | */ | |
273 | static inline void ww_acquire_init(struct ww_acquire_ctx *ctx, | |
274 | struct ww_class *ww_class) | |
275 | { | |
276 | ctx->task = current; | |
277 | ctx->stamp = atomic_long_inc_return(&ww_class->stamp); | |
278 | ctx->acquired = 0; | |
279 | #ifdef CONFIG_DEBUG_MUTEXES | |
280 | ctx->ww_class = ww_class; | |
281 | ctx->done_acquire = 0; | |
282 | ctx->contending_lock = NULL; | |
283 | #endif | |
284 | #ifdef CONFIG_DEBUG_LOCK_ALLOC | |
285 | debug_check_no_locks_freed((void *)ctx, sizeof(*ctx)); | |
286 | lockdep_init_map(&ctx->dep_map, ww_class->acquire_name, | |
287 | &ww_class->acquire_key, 0); | |
288 | mutex_acquire(&ctx->dep_map, 0, 0, _RET_IP_); | |
289 | #endif | |
23010027 DV |
290 | #ifdef CONFIG_DEBUG_WW_MUTEX_SLOWPATH |
291 | ctx->deadlock_inject_interval = 1; | |
292 | ctx->deadlock_inject_countdown = ctx->stamp & 0xf; | |
293 | #endif | |
040a0a37 ML |
294 | } |
295 | ||
296 | /** | |
297 | * ww_acquire_done - marks the end of the acquire phase | |
298 | * @ctx: the acquire context | |
299 | * | |
300 | * Marks the end of the acquire phase, any further w/w mutex lock calls using | |
301 | * this context are forbidden. | |
302 | * | |
303 | * Calling this function is optional, it is just useful to document w/w mutex | |
304 | * code and clearly designated the acquire phase from actually using the locked | |
305 | * data structures. | |
306 | */ | |
307 | static inline void ww_acquire_done(struct ww_acquire_ctx *ctx) | |
308 | { | |
309 | #ifdef CONFIG_DEBUG_MUTEXES | |
310 | lockdep_assert_held(ctx); | |
311 | ||
312 | DEBUG_LOCKS_WARN_ON(ctx->done_acquire); | |
313 | ctx->done_acquire = 1; | |
314 | #endif | |
315 | } | |
316 | ||
317 | /** | |
318 | * ww_acquire_fini - releases a w/w acquire context | |
319 | * @ctx: the acquire context to free | |
320 | * | |
321 | * Releases a w/w acquire context. This must be called _after_ all acquired w/w | |
322 | * mutexes have been released with ww_mutex_unlock. | |
323 | */ | |
324 | static inline void ww_acquire_fini(struct ww_acquire_ctx *ctx) | |
325 | { | |
326 | #ifdef CONFIG_DEBUG_MUTEXES | |
327 | mutex_release(&ctx->dep_map, 0, _THIS_IP_); | |
328 | ||
329 | DEBUG_LOCKS_WARN_ON(ctx->acquired); | |
330 | if (!config_enabled(CONFIG_PROVE_LOCKING)) | |
331 | /* | |
332 | * lockdep will normally handle this, | |
333 | * but fail without anyway | |
334 | */ | |
335 | ctx->done_acquire = 1; | |
336 | ||
337 | if (!config_enabled(CONFIG_DEBUG_LOCK_ALLOC)) | |
338 | /* ensure ww_acquire_fini will still fail if called twice */ | |
339 | ctx->acquired = ~0U; | |
340 | #endif | |
341 | } | |
342 | ||
343 | extern int __must_check __ww_mutex_lock(struct ww_mutex *lock, | |
344 | struct ww_acquire_ctx *ctx); | |
345 | extern int __must_check __ww_mutex_lock_interruptible(struct ww_mutex *lock, | |
346 | struct ww_acquire_ctx *ctx); | |
347 | ||
348 | /** | |
349 | * ww_mutex_lock - acquire the w/w mutex | |
350 | * @lock: the mutex to be acquired | |
351 | * @ctx: w/w acquire context, or NULL to acquire only a single lock. | |
352 | * | |
353 | * Lock the w/w mutex exclusively for this task. | |
354 | * | |
355 | * Deadlocks within a given w/w class of locks are detected and handled with the | |
356 | * wait/wound algorithm. If the lock isn't immediately avaiable this function | |
357 | * will either sleep until it is (wait case). Or it selects the current context | |
358 | * for backing off by returning -EDEADLK (wound case). Trying to acquire the | |
359 | * same lock with the same context twice is also detected and signalled by | |
360 | * returning -EALREADY. Returns 0 if the mutex was successfully acquired. | |
361 | * | |
362 | * In the wound case the caller must release all currently held w/w mutexes for | |
363 | * the given context and then wait for this contending lock to be available by | |
364 | * calling ww_mutex_lock_slow. Alternatively callers can opt to not acquire this | |
365 | * lock and proceed with trying to acquire further w/w mutexes (e.g. when | |
366 | * scanning through lru lists trying to free resources). | |
367 | * | |
368 | * The mutex must later on be released by the same task that | |
369 | * acquired it. The task may not exit without first unlocking the mutex. Also, | |
370 | * kernel memory where the mutex resides must not be freed with the mutex still | |
371 | * locked. The mutex must first be initialized (or statically defined) before it | |
372 | * can be locked. memset()-ing the mutex to 0 is not allowed. The mutex must be | |
373 | * of the same w/w lock class as was used to initialize the acquire context. | |
374 | * | |
375 | * A mutex acquired with this function must be released with ww_mutex_unlock. | |
376 | */ | |
377 | static inline int ww_mutex_lock(struct ww_mutex *lock, struct ww_acquire_ctx *ctx) | |
378 | { | |
379 | if (ctx) | |
380 | return __ww_mutex_lock(lock, ctx); | |
381 | else { | |
382 | mutex_lock(&lock->base); | |
383 | return 0; | |
384 | } | |
385 | } | |
386 | ||
387 | /** | |
388 | * ww_mutex_lock_interruptible - acquire the w/w mutex, interruptible | |
389 | * @lock: the mutex to be acquired | |
390 | * @ctx: w/w acquire context | |
391 | * | |
392 | * Lock the w/w mutex exclusively for this task. | |
393 | * | |
394 | * Deadlocks within a given w/w class of locks are detected and handled with the | |
395 | * wait/wound algorithm. If the lock isn't immediately avaiable this function | |
396 | * will either sleep until it is (wait case). Or it selects the current context | |
397 | * for backing off by returning -EDEADLK (wound case). Trying to acquire the | |
398 | * same lock with the same context twice is also detected and signalled by | |
399 | * returning -EALREADY. Returns 0 if the mutex was successfully acquired. If a | |
400 | * signal arrives while waiting for the lock then this function returns -EINTR. | |
401 | * | |
402 | * In the wound case the caller must release all currently held w/w mutexes for | |
403 | * the given context and then wait for this contending lock to be available by | |
404 | * calling ww_mutex_lock_slow_interruptible. Alternatively callers can opt to | |
405 | * not acquire this lock and proceed with trying to acquire further w/w mutexes | |
406 | * (e.g. when scanning through lru lists trying to free resources). | |
407 | * | |
408 | * The mutex must later on be released by the same task that | |
409 | * acquired it. The task may not exit without first unlocking the mutex. Also, | |
410 | * kernel memory where the mutex resides must not be freed with the mutex still | |
411 | * locked. The mutex must first be initialized (or statically defined) before it | |
412 | * can be locked. memset()-ing the mutex to 0 is not allowed. The mutex must be | |
413 | * of the same w/w lock class as was used to initialize the acquire context. | |
414 | * | |
415 | * A mutex acquired with this function must be released with ww_mutex_unlock. | |
416 | */ | |
417 | static inline int __must_check ww_mutex_lock_interruptible(struct ww_mutex *lock, | |
418 | struct ww_acquire_ctx *ctx) | |
419 | { | |
420 | if (ctx) | |
421 | return __ww_mutex_lock_interruptible(lock, ctx); | |
422 | else | |
423 | return mutex_lock_interruptible(&lock->base); | |
424 | } | |
425 | ||
426 | /** | |
427 | * ww_mutex_lock_slow - slowpath acquiring of the w/w mutex | |
428 | * @lock: the mutex to be acquired | |
429 | * @ctx: w/w acquire context | |
430 | * | |
431 | * Acquires a w/w mutex with the given context after a wound case. This function | |
432 | * will sleep until the lock becomes available. | |
433 | * | |
434 | * The caller must have released all w/w mutexes already acquired with the | |
435 | * context and then call this function on the contended lock. | |
436 | * | |
437 | * Afterwards the caller may continue to (re)acquire the other w/w mutexes it | |
438 | * needs with ww_mutex_lock. Note that the -EALREADY return code from | |
439 | * ww_mutex_lock can be used to avoid locking this contended mutex twice. | |
440 | * | |
441 | * It is forbidden to call this function with any other w/w mutexes associated | |
442 | * with the context held. It is forbidden to call this on anything else than the | |
443 | * contending mutex. | |
444 | * | |
445 | * Note that the slowpath lock acquiring can also be done by calling | |
446 | * ww_mutex_lock directly. This function here is simply to help w/w mutex | |
447 | * locking code readability by clearly denoting the slowpath. | |
448 | */ | |
449 | static inline void | |
450 | ww_mutex_lock_slow(struct ww_mutex *lock, struct ww_acquire_ctx *ctx) | |
451 | { | |
452 | int ret; | |
453 | #ifdef CONFIG_DEBUG_MUTEXES | |
454 | DEBUG_LOCKS_WARN_ON(!ctx->contending_lock); | |
455 | #endif | |
456 | ret = ww_mutex_lock(lock, ctx); | |
457 | (void)ret; | |
458 | } | |
459 | ||
460 | /** | |
461 | * ww_mutex_lock_slow_interruptible - slowpath acquiring of the w/w mutex, | |
462 | * interruptible | |
463 | * @lock: the mutex to be acquired | |
464 | * @ctx: w/w acquire context | |
465 | * | |
466 | * Acquires a w/w mutex with the given context after a wound case. This function | |
467 | * will sleep until the lock becomes available and returns 0 when the lock has | |
468 | * been acquired. If a signal arrives while waiting for the lock then this | |
469 | * function returns -EINTR. | |
470 | * | |
471 | * The caller must have released all w/w mutexes already acquired with the | |
472 | * context and then call this function on the contended lock. | |
473 | * | |
474 | * Afterwards the caller may continue to (re)acquire the other w/w mutexes it | |
475 | * needs with ww_mutex_lock. Note that the -EALREADY return code from | |
476 | * ww_mutex_lock can be used to avoid locking this contended mutex twice. | |
477 | * | |
478 | * It is forbidden to call this function with any other w/w mutexes associated | |
479 | * with the given context held. It is forbidden to call this on anything else | |
480 | * than the contending mutex. | |
481 | * | |
482 | * Note that the slowpath lock acquiring can also be done by calling | |
483 | * ww_mutex_lock_interruptible directly. This function here is simply to help | |
484 | * w/w mutex locking code readability by clearly denoting the slowpath. | |
485 | */ | |
486 | static inline int __must_check | |
487 | ww_mutex_lock_slow_interruptible(struct ww_mutex *lock, | |
488 | struct ww_acquire_ctx *ctx) | |
489 | { | |
490 | #ifdef CONFIG_DEBUG_MUTEXES | |
491 | DEBUG_LOCKS_WARN_ON(!ctx->contending_lock); | |
492 | #endif | |
493 | return ww_mutex_lock_interruptible(lock, ctx); | |
494 | } | |
495 | ||
496 | extern void ww_mutex_unlock(struct ww_mutex *lock); | |
497 | ||
498 | /** | |
499 | * ww_mutex_trylock - tries to acquire the w/w mutex without acquire context | |
500 | * @lock: mutex to lock | |
501 | * | |
502 | * Trylocks a mutex without acquire context, so no deadlock detection is | |
503 | * possible. Returns 1 if the mutex has been acquired successfully, 0 otherwise. | |
504 | */ | |
505 | static inline int __must_check ww_mutex_trylock(struct ww_mutex *lock) | |
506 | { | |
507 | return mutex_trylock(&lock->base); | |
508 | } | |
509 | ||
510 | /*** | |
511 | * ww_mutex_destroy - mark a w/w mutex unusable | |
512 | * @lock: the mutex to be destroyed | |
513 | * | |
514 | * This function marks the mutex uninitialized, and any subsequent | |
515 | * use of the mutex is forbidden. The mutex must not be locked when | |
516 | * this function is called. | |
517 | */ | |
518 | static inline void ww_mutex_destroy(struct ww_mutex *lock) | |
519 | { | |
520 | mutex_destroy(&lock->base); | |
521 | } | |
522 | ||
523 | /** | |
524 | * ww_mutex_is_locked - is the w/w mutex locked | |
525 | * @lock: the mutex to be queried | |
526 | * | |
527 | * Returns 1 if the mutex is locked, 0 if unlocked. | |
528 | */ | |
529 | static inline bool ww_mutex_is_locked(struct ww_mutex *lock) | |
530 | { | |
531 | return mutex_is_locked(&lock->base); | |
532 | } | |
533 | ||
a511e3f9 | 534 | extern int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock); |
b1fca266 | 535 | |
335d7afb GS |
536 | #ifndef CONFIG_HAVE_ARCH_MUTEX_CPU_RELAX |
537 | #define arch_mutex_cpu_relax() cpu_relax() | |
538 | #endif | |
539 | ||
6053ee3b | 540 | #endif |