kernel/locking/rtmutex_api.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * rtmutex API
   4  */
   5 #include <linux/spinlock.h>
   6 #include <linux/export.h>
   7
   8 #define RT_MUTEX_BUILD_MUTEX
   9 #include "rtmutex.c"
  10
  11 /*
  12  * Max number of times we'll walk the boosting chain:
  13  */
  14 int max_lock_depth = 1024;
  15
  16 /*
  17  * Debug aware fast / slowpath lock,trylock,unlock
  18  *
  19  * The atomic acquire/release ops are compiled away, when either the
  20  * architecture does not support cmpxchg or when debugging is enabled.
  21  */
  22 static __always_inline int __rt_mutex_lock_common(struct rt_mutex *lock,
  23                                                   unsigned int state,
  24                                                   struct lockdep_map *nest_lock,
  25                                                   unsigned int subclass)
  26 {
  27         int ret;
  28
  29         might_sleep();
  30         mutex_acquire_nest(&lock->dep_map, subclass, 0, nest_lock, _RET_IP_);
  31         ret = __rt_mutex_lock(&lock->rtmutex, state);
  32         if (ret)
  33                 mutex_release(&lock->dep_map, _RET_IP_);
  34         return ret;
  35 }
  36
  37 void rt_mutex_base_init(struct rt_mutex_base *rtb)
  38 {
  39         __rt_mutex_base_init(rtb);
  40 }
  41 EXPORT_SYMBOL(rt_mutex_base_init);
  42
  43 #ifdef CONFIG_DEBUG_LOCK_ALLOC
  44 /**
  45  * rt_mutex_lock_nested - lock a rt_mutex
  46  *
  47  * @lock: the rt_mutex to be locked
  48  * @subclass: the lockdep subclass
  49  */
  50 void __sched rt_mutex_lock_nested(struct rt_mutex *lock, unsigned int subclass)
  51 {
  52         __rt_mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, NULL, subclass);
  53 }
  54 EXPORT_SYMBOL_GPL(rt_mutex_lock_nested);
  55
  56 void __sched _rt_mutex_lock_nest_lock(struct rt_mutex *lock, struct lockdep_map *nest_lock)
  57 {
  58         __rt_mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, nest_lock, 0);
  59 }
  60 EXPORT_SYMBOL_GPL(_rt_mutex_lock_nest_lock);
  61
  62 #else /* !CONFIG_DEBUG_LOCK_ALLOC */
  63
  64 /**
  65  * rt_mutex_lock - lock a rt_mutex
  66  *
  67  * @lock: the rt_mutex to be locked
  68  */
  69 void __sched rt_mutex_lock(struct rt_mutex *lock)
  70 {
  71         __rt_mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, NULL, 0);
  72 }
  73 EXPORT_SYMBOL_GPL(rt_mutex_lock);
  74 #endif
  75
  76 /**
  77  * rt_mutex_lock_interruptible - lock a rt_mutex interruptible
  78  *
  79  * @lock:               the rt_mutex to be locked
  80  *
  81  * Returns:
  82  *  0           on success
  83  * -EINTR       when interrupted by a signal
  84  */
  85 int __sched rt_mutex_lock_interruptible(struct rt_mutex *lock)
  86 {
  87         return __rt_mutex_lock_common(lock, TASK_INTERRUPTIBLE, NULL, 0);
  88 }
  89 EXPORT_SYMBOL_GPL(rt_mutex_lock_interruptible);
  90
  91 /**
  92  * rt_mutex_lock_killable - lock a rt_mutex killable
  93  *
  94  * @lock:               the rt_mutex to be locked
  95  *
  96  * Returns:
  97  *  0           on success
  98  * -EINTR       when interrupted by a signal
  99  */
 100 int __sched rt_mutex_lock_killable(struct rt_mutex *lock)
 101 {
 102         return __rt_mutex_lock_common(lock, TASK_KILLABLE, NULL, 0);
 103 }
 104 EXPORT_SYMBOL_GPL(rt_mutex_lock_killable);
 105
 106 /**
 107  * rt_mutex_trylock - try to lock a rt_mutex
 108  *
 109  * @lock:       the rt_mutex to be locked
 110  *
 111  * This function can only be called in thread context. It's safe to call it
 112  * from atomic regions, but not from hard or soft interrupt context.
 113  *
 114  * Returns:
 115  *  1 on success
 116  *  0 on contention
 117  */
 118 int __sched rt_mutex_trylock(struct rt_mutex *lock)
 119 {
 120         int ret;
 121
 122         if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES) && WARN_ON_ONCE(!in_task()))
 123                 return 0;
 124
 125         ret = __rt_mutex_trylock(&lock->rtmutex);
 126         if (ret)
 127                 mutex_acquire(&lock->dep_map, 0, 1, _RET_IP_);
 128
 129         return ret;
 130 }
 131 EXPORT_SYMBOL_GPL(rt_mutex_trylock);
 132
 133 /**
 134  * rt_mutex_unlock - unlock a rt_mutex
 135  *
 136  * @lock: the rt_mutex to be unlocked
 137  */
 138 void __sched rt_mutex_unlock(struct rt_mutex *lock)
 139 {
 140         mutex_release(&lock->dep_map, _RET_IP_);
 141         __rt_mutex_unlock(&lock->rtmutex);
 142 }
 143 EXPORT_SYMBOL_GPL(rt_mutex_unlock);
 144
 145 /*
 146  * Futex variants, must not use fastpath.
 147  */
 148 int __sched rt_mutex_futex_trylock(struct rt_mutex_base *lock)
 149 {
 150         return rt_mutex_slowtrylock(lock);
 151 }
 152
 153 int __sched __rt_mutex_futex_trylock(struct rt_mutex_base *lock)
 154 {
 155         return __rt_mutex_slowtrylock(lock);
 156 }
 157
 158 /**
 159  * __rt_mutex_futex_unlock - Futex variant, that since futex variants
 160  * do not use the fast-path, can be simple and will not need to retry.
 161  *
 162  * @lock:       The rt_mutex to be unlocked
 163  * @wqh:        The wake queue head from which to get the next lock waiter
 164  */
 165 bool __sched __rt_mutex_futex_unlock(struct rt_mutex_base *lock,
 166                                      struct rt_wake_q_head *wqh)
 167 {
 168         lockdep_assert_held(&lock->wait_lock);
 169
 170         debug_rt_mutex_unlock(lock);
 171
 172         if (!rt_mutex_has_waiters(lock)) {
 173                 lock->owner = NULL;
 174                 return false; /* done */
 175         }
 176
 177         /*
 178          * mark_wakeup_next_waiter() deboosts and retains preemption
 179          * disabled when dropping the wait_lock, to avoid inversion prior
 180          * to the wakeup.  preempt_disable() therein pairs with the
 181          * preempt_enable() in rt_mutex_postunlock().
 182          */
 183         mark_wakeup_next_waiter(wqh, lock);
 184
 185         return true; /* call postunlock() */
 186 }
 187
 188 void __sched rt_mutex_futex_unlock(struct rt_mutex_base *lock)
 189 {
 190         DEFINE_RT_WAKE_Q(wqh);
 191         unsigned long flags;
 192         bool postunlock;
 193
 194         raw_spin_lock_irqsave(&lock->wait_lock, flags);
 195         postunlock = __rt_mutex_futex_unlock(lock, &wqh);
 196         raw_spin_unlock_irqrestore(&lock->wait_lock, flags);
 197
 198         if (postunlock)
 199                 rt_mutex_postunlock(&wqh);
 200 }
 201
 202 /**
 203  * __rt_mutex_init - initialize the rt_mutex
 204  *
 205  * @lock:       The rt_mutex to be initialized
 206  * @name:       The lock name used for debugging
 207  * @key:        The lock class key used for debugging
 208  *
 209  * Initialize the rt_mutex to unlocked state.
 210  *
 211  * Initializing of a locked rt_mutex is not allowed
 212  */
 213 void __sched __rt_mutex_init(struct rt_mutex *lock, const char *name,
 214                              struct lock_class_key *key)
 215 {
 216         debug_check_no_locks_freed((void *)lock, sizeof(*lock));
 217         __rt_mutex_base_init(&lock->rtmutex);
 218         lockdep_init_map_wait(&lock->dep_map, name, key, 0, LD_WAIT_SLEEP);
 219 }
 220 EXPORT_SYMBOL_GPL(__rt_mutex_init);
 221
 222 /**
 223  * rt_mutex_init_proxy_locked - initialize and lock a rt_mutex on behalf of a
 224  *                              proxy owner
 225  *
 226  * @lock:       the rt_mutex to be locked
 227  * @proxy_owner:the task to set as owner
 228  *
 229  * No locking. Caller has to do serializing itself
 230  *
 231  * Special API call for PI-futex support. This initializes the rtmutex and
 232  * assigns it to @proxy_owner. Concurrent operations on the rtmutex are not
 233  * possible at this point because the pi_state which contains the rtmutex
 234  * is not yet visible to other tasks.
 235  */
 236 void __sched rt_mutex_init_proxy_locked(struct rt_mutex_base *lock,
 237                                         struct task_struct *proxy_owner)
 238 {
 239         static struct lock_class_key pi_futex_key;
 240
 241         __rt_mutex_base_init(lock);
 242         /*
 243          * On PREEMPT_RT the futex hashbucket spinlock becomes 'sleeping'
 244          * and rtmutex based. That causes a lockdep false positive, because
 245          * some of the futex functions invoke spin_unlock(&hb->lock) with
 246          * the wait_lock of the rtmutex associated to the pi_futex held.
 247          * spin_unlock() in turn takes wait_lock of the rtmutex on which
 248          * the spinlock is based, which makes lockdep notice a lock
 249          * recursion. Give the futex/rtmutex wait_lock a separate key.
 250          */
 251         lockdep_set_class(&lock->wait_lock, &pi_futex_key);
 252         rt_mutex_set_owner(lock, proxy_owner);
 253 }
 254
 255 /**
 256  * rt_mutex_proxy_unlock - release a lock on behalf of owner
 257  *
 258  * @lock:       the rt_mutex to be locked
 259  *
 260  * No locking. Caller has to do serializing itself
 261  *
 262  * Special API call for PI-futex support. This just cleans up the rtmutex
 263  * (debugging) state. Concurrent operations on this rt_mutex are not
 264  * possible because it belongs to the pi_state which is about to be freed
 265  * and it is not longer visible to other tasks.
 266  */
 267 void __sched rt_mutex_proxy_unlock(struct rt_mutex_base *lock)
 268 {
 269         debug_rt_mutex_proxy_unlock(lock);
 270         rt_mutex_clear_owner(lock);
 271 }
 272
 273 /**
 274  * __rt_mutex_start_proxy_lock() - Start lock acquisition for another task
 275  * @lock:               the rt_mutex to take
 276  * @waiter:             the pre-initialized rt_mutex_waiter
 277  * @task:               the task to prepare
 278  * @wake_q:             the wake_q to wake tasks after we release the wait_lock
 279  *
 280  * Starts the rt_mutex acquire; it enqueues the @waiter and does deadlock
 281  * detection. It does not wait, see rt_mutex_wait_proxy_lock() for that.
 282  *
 283  * NOTE: does _NOT_ remove the @waiter on failure; must either call
 284  * rt_mutex_wait_proxy_lock() or rt_mutex_cleanup_proxy_lock() after this.
 285  *
 286  * Returns:
 287  *  0 - task blocked on lock
 288  *  1 - acquired the lock for task, caller should wake it up
 289  * <0 - error
 290  *
 291  * Special API call for PI-futex support.
 292  */
 293 int __sched __rt_mutex_start_proxy_lock(struct rt_mutex_base *lock,
 294                                         struct rt_mutex_waiter *waiter,
 295                                         struct task_struct *task,
 296                                         struct wake_q_head *wake_q)
 297 {
 298         int ret;
 299
 300         lockdep_assert_held(&lock->wait_lock);
 301
 302         if (try_to_take_rt_mutex(lock, task, NULL))
 303                 return 1;
 304
 305         /* We enforce deadlock detection for futexes */
 306         ret = task_blocks_on_rt_mutex(lock, waiter, task, NULL,
 307                                       RT_MUTEX_FULL_CHAINWALK, wake_q);
 308
 309         if (ret && !rt_mutex_owner(lock)) {
 310                 /*
 311                  * Reset the return value. We might have
 312                  * returned with -EDEADLK and the owner
 313                  * released the lock while we were walking the
 314                  * pi chain.  Let the waiter sort it out.
 315                  */
 316                 ret = 0;
 317         }
 318
 319         return ret;
 320 }
 321
 322 /**
 323  * rt_mutex_start_proxy_lock() - Start lock acquisition for another task
 324  * @lock:               the rt_mutex to take
 325  * @waiter:             the pre-initialized rt_mutex_waiter
 326  * @task:               the task to prepare
 327  *
 328  * Starts the rt_mutex acquire; it enqueues the @waiter and does deadlock
 329  * detection. It does not wait, see rt_mutex_wait_proxy_lock() for that.
 330  *
 331  * NOTE: unlike __rt_mutex_start_proxy_lock this _DOES_ remove the @waiter
 332  * on failure.
 333  *
 334  * Returns:
 335  *  0 - task blocked on lock
 336  *  1 - acquired the lock for task, caller should wake it up
 337  * <0 - error
 338  *
 339  * Special API call for PI-futex support.
 340  */
 341 int __sched rt_mutex_start_proxy_lock(struct rt_mutex_base *lock,
 342                                       struct rt_mutex_waiter *waiter,
 343                                       struct task_struct *task)
 344 {
 345         int ret;
 346         DEFINE_WAKE_Q(wake_q);
 347
 348         raw_spin_lock_irq(&lock->wait_lock);
 349         ret = __rt_mutex_start_proxy_lock(lock, waiter, task, &wake_q);
 350         if (unlikely(ret))
 351                 remove_waiter(lock, waiter);
 352         preempt_disable();
 353         raw_spin_unlock_irq(&lock->wait_lock);
 354         wake_up_q(&wake_q);
 355         preempt_enable();
 356
 357         return ret;
 358 }
 359
 360 /**
 361  * rt_mutex_wait_proxy_lock() - Wait for lock acquisition
 362  * @lock:               the rt_mutex we were woken on
 363  * @to:                 the timeout, null if none. hrtimer should already have
 364  *                      been started.
 365  * @waiter:             the pre-initialized rt_mutex_waiter
 366  *
 367  * Wait for the lock acquisition started on our behalf by
 368  * rt_mutex_start_proxy_lock(). Upon failure, the caller must call
 369  * rt_mutex_cleanup_proxy_lock().
 370  *
 371  * Returns:
 372  *  0 - success
 373  * <0 - error, one of -EINTR, -ETIMEDOUT
 374  *
 375  * Special API call for PI-futex support
 376  */
 377 int __sched rt_mutex_wait_proxy_lock(struct rt_mutex_base *lock,
 378                                      struct hrtimer_sleeper *to,
 379                                      struct rt_mutex_waiter *waiter)
 380 {
 381         int ret;
 382
 383         raw_spin_lock_irq(&lock->wait_lock);
 384         /* sleep on the mutex */
 385         set_current_state(TASK_INTERRUPTIBLE);
 386         ret = rt_mutex_slowlock_block(lock, NULL, TASK_INTERRUPTIBLE, to, waiter, NULL);
 387         /*
 388          * try_to_take_rt_mutex() sets the waiter bit unconditionally. We might
 389          * have to fix that up.
 390          */
 391         fixup_rt_mutex_waiters(lock, true);
 392         raw_spin_unlock_irq(&lock->wait_lock);
 393
 394         return ret;
 395 }
 396
 397 /**
 398  * rt_mutex_cleanup_proxy_lock() - Cleanup failed lock acquisition
 399  * @lock:               the rt_mutex we were woken on
 400  * @waiter:             the pre-initialized rt_mutex_waiter
 401  *
 402  * Attempt to clean up after a failed __rt_mutex_start_proxy_lock() or
 403  * rt_mutex_wait_proxy_lock().
 404  *
 405  * Unless we acquired the lock; we're still enqueued on the wait-list and can
 406  * in fact still be granted ownership until we're removed. Therefore we can
 407  * find we are in fact the owner and must disregard the
 408  * rt_mutex_wait_proxy_lock() failure.
 409  *
 410  * Returns:
 411  *  true  - did the cleanup, we done.
 412  *  false - we acquired the lock after rt_mutex_wait_proxy_lock() returned,
 413  *          caller should disregards its return value.
 414  *
 415  * Special API call for PI-futex support
 416  */
 417 bool __sched rt_mutex_cleanup_proxy_lock(struct rt_mutex_base *lock,
 418                                          struct rt_mutex_waiter *waiter)
 419 {
 420         bool cleanup = false;
 421
 422         raw_spin_lock_irq(&lock->wait_lock);
 423         /*
 424          * Do an unconditional try-lock, this deals with the lock stealing
 425          * state where __rt_mutex_futex_unlock() -> mark_wakeup_next_waiter()
 426          * sets a NULL owner.
 427          *
 428          * We're not interested in the return value, because the subsequent
 429          * test on rt_mutex_owner() will infer that. If the trylock succeeded,
 430          * we will own the lock and it will have removed the waiter. If we
 431          * failed the trylock, we're still not owner and we need to remove
 432          * ourselves.
 433          */
 434         try_to_take_rt_mutex(lock, current, waiter);
 435         /*
 436          * Unless we're the owner; we're still enqueued on the wait_list.
 437          * So check if we became owner, if not, take us off the wait_list.
 438          */
 439         if (rt_mutex_owner(lock) != current) {
 440                 remove_waiter(lock, waiter);
 441                 cleanup = true;
 442         }
 443         /*
 444          * try_to_take_rt_mutex() sets the waiter bit unconditionally. We might
 445          * have to fix that up.
 446          */
 447         fixup_rt_mutex_waiters(lock, false);
 448
 449         raw_spin_unlock_irq(&lock->wait_lock);
 450
 451         return cleanup;
 452 }
 453
 454 /*
 455  * Recheck the pi chain, in case we got a priority setting
 456  *
 457  * Called from sched_setscheduler
 458  */
 459 void __sched rt_mutex_adjust_pi(struct task_struct *task)
 460 {
 461         struct rt_mutex_waiter *waiter;
 462         struct rt_mutex_base *next_lock;
 463         unsigned long flags;
 464
 465         raw_spin_lock_irqsave(&task->pi_lock, flags);
 466
 467         waiter = task->pi_blocked_on;
 468         if (!waiter || rt_waiter_node_equal(&waiter->tree, task_to_waiter_node(task))) {
 469                 raw_spin_unlock_irqrestore(&task->pi_lock, flags);
 470                 return;
 471         }
 472         next_lock = waiter->lock;
 473         raw_spin_unlock_irqrestore(&task->pi_lock, flags);
 474
 475         /* gets dropped in rt_mutex_adjust_prio_chain()! */
 476         get_task_struct(task);
 477
 478         rt_mutex_adjust_prio_chain(task, RT_MUTEX_MIN_CHAINWALK, NULL,
 479                                    next_lock, NULL, task);
 480 }
 481
 482 /*
 483  * Performs the wakeup of the top-waiter and re-enables preemption.
 484  */
 485 void __sched rt_mutex_postunlock(struct rt_wake_q_head *wqh)
 486 {
 487         rt_mutex_wake_up_q(wqh);
 488 }
 489
 490 #ifdef CONFIG_DEBUG_RT_MUTEXES
 491 void rt_mutex_debug_task_free(struct task_struct *task)
 492 {
 493         DEBUG_LOCKS_WARN_ON(!RB_EMPTY_ROOT(&task->pi_waiters.rb_root));
 494         DEBUG_LOCKS_WARN_ON(task->pi_blocked_on);
 495 }
 496 #endif
 497
 498 #ifdef CONFIG_PREEMPT_RT
 499 /* Mutexes */
 500 void __mutex_rt_init(struct mutex *mutex, const char *name,
 501                      struct lock_class_key *key)
 502 {
 503         debug_check_no_locks_freed((void *)mutex, sizeof(*mutex));
 504         lockdep_init_map_wait(&mutex->dep_map, name, key, 0, LD_WAIT_SLEEP);
 505 }
 506 EXPORT_SYMBOL(__mutex_rt_init);
 507
 508 static __always_inline int __mutex_lock_common(struct mutex *lock,
 509                                                unsigned int state,
 510                                                unsigned int subclass,
 511                                                struct lockdep_map *nest_lock,
 512                                                unsigned long ip)
 513 {
 514         int ret;
 515
 516         might_sleep();
 517         mutex_acquire_nest(&lock->dep_map, subclass, 0, nest_lock, ip);
 518         ret = __rt_mutex_lock(&lock->rtmutex, state);
 519         if (ret)
 520                 mutex_release(&lock->dep_map, ip);
 521         else
 522                 lock_acquired(&lock->dep_map, ip);
 523         return ret;
 524 }
 525
 526 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 527 void __sched mutex_lock_nested(struct mutex *lock, unsigned int subclass)
 528 {
 529         __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, subclass, NULL, _RET_IP_);
 530 }
 531 EXPORT_SYMBOL_GPL(mutex_lock_nested);
 532
 533 void __sched _mutex_lock_nest_lock(struct mutex *lock,
 534                                    struct lockdep_map *nest_lock)
 535 {
 536         __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, 0, nest_lock, _RET_IP_);
 537 }
 538 EXPORT_SYMBOL_GPL(_mutex_lock_nest_lock);
 539
 540 int __sched mutex_lock_interruptible_nested(struct mutex *lock,
 541                                             unsigned int subclass)
 542 {
 543         return __mutex_lock_common(lock, TASK_INTERRUPTIBLE, subclass, NULL, _RET_IP_);
 544 }
 545 EXPORT_SYMBOL_GPL(mutex_lock_interruptible_nested);
 546
 547 int __sched mutex_lock_killable_nested(struct mutex *lock,
 548                                             unsigned int subclass)
 549 {
 550         return __mutex_lock_common(lock, TASK_KILLABLE, subclass, NULL, _RET_IP_);
 551 }
 552 EXPORT_SYMBOL_GPL(mutex_lock_killable_nested);
 553
 554 void __sched mutex_lock_io_nested(struct mutex *lock, unsigned int subclass)
 555 {
 556         int token;
 557
 558         might_sleep();
 559
 560         token = io_schedule_prepare();
 561         __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, subclass, NULL, _RET_IP_);
 562         io_schedule_finish(token);
 563 }
 564 EXPORT_SYMBOL_GPL(mutex_lock_io_nested);
 565
 566 #else /* CONFIG_DEBUG_LOCK_ALLOC */
 567
 568 void __sched mutex_lock(struct mutex *lock)
 569 {
 570         __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, 0, NULL, _RET_IP_);
 571 }
 572 EXPORT_SYMBOL(mutex_lock);
 573
 574 int __sched mutex_lock_interruptible(struct mutex *lock)
 575 {
 576         return __mutex_lock_common(lock, TASK_INTERRUPTIBLE, 0, NULL, _RET_IP_);
 577 }
 578 EXPORT_SYMBOL(mutex_lock_interruptible);
 579
 580 int __sched mutex_lock_killable(struct mutex *lock)
 581 {
 582         return __mutex_lock_common(lock, TASK_KILLABLE, 0, NULL, _RET_IP_);
 583 }
 584 EXPORT_SYMBOL(mutex_lock_killable);
 585
 586 void __sched mutex_lock_io(struct mutex *lock)
 587 {
 588         int token = io_schedule_prepare();
 589
 590         __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, 0, NULL, _RET_IP_);
 591         io_schedule_finish(token);
 592 }
 593 EXPORT_SYMBOL(mutex_lock_io);
 594 #endif /* !CONFIG_DEBUG_LOCK_ALLOC */
 595
 596 int __sched mutex_trylock(struct mutex *lock)
 597 {
 598         int ret;
 599
 600         if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES) && WARN_ON_ONCE(!in_task()))
 601                 return 0;
 602
 603         ret = __rt_mutex_trylock(&lock->rtmutex);
 604         if (ret)
 605                 mutex_acquire(&lock->dep_map, 0, 1, _RET_IP_);
 606
 607         return ret;
 608 }
 609 EXPORT_SYMBOL(mutex_trylock);
 610
 611 void __sched mutex_unlock(struct mutex *lock)
 612 {
 613         mutex_release(&lock->dep_map, _RET_IP_);
 614         __rt_mutex_unlock(&lock->rtmutex);
 615 }
 616 EXPORT_SYMBOL(mutex_unlock);
 617
 618 #endif /* CONFIG_PREEMPT_RT */