[GitHub/mt8127/android_kernel_alcatel_ttab.git] / kernel / mutex.c

/*
 * kernel/mutex.c
 *
 * Mutexes: blocking mutual exclusion locks
 *
 * Started by Ingo Molnar:
 *
 *  Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
 *
 * Many thanks to Arjan van de Ven, Thomas Gleixner, Steven Rostedt and
 * David Howells for suggestions and improvements.
 *
 * Also see Documentation/mutex-design.txt.
 */
#include <linux/mutex.h>
#include <linux/sched.h>
#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <linux/debug_locks.h>

/*
 * In the DEBUG case we are using the "NULL fastpath" for mutexes,
 * which forces all calls into the slowpath:
 */
#ifdef CONFIG_DEBUG_MUTEXES
# include "mutex-debug.h"
# include <asm-generic/mutex-null.h>
#else
# include "mutex.h"
# include <asm/mutex.h>
#endif

/***
 * mutex_init - initialize the mutex
 * @lock: the mutex to be initialized
 *
 * Initialize the mutex to unlocked state.
 *
 * It is not allowed to initialize an already locked mutex.
 */
void
__mutex_init(struct mutex *lock, const char *name, struct lock_class_key *key)
{
	atomic_set(&lock->count, 1);
	spin_lock_init(&lock->wait_lock);
	INIT_LIST_HEAD(&lock->wait_list);

	debug_mutex_init(lock, name, key);
}

EXPORT_SYMBOL(__mutex_init);

#ifndef CONFIG_DEBUG_LOCK_ALLOC
/*
 * We split the mutex lock/unlock logic into separate fastpath and
 * slowpath functions, to reduce the register pressure on the fastpath.
 * We also put the fastpath first in the kernel image, to make sure the
 * branch is predicted by the CPU as default-untaken.
 */
static void fastcall noinline __sched
__mutex_lock_slowpath(atomic_t *lock_count);

/***
 * mutex_lock - acquire the mutex
 * @lock: the mutex to be acquired
 *
 * Lock the mutex exclusively for this task. If the mutex is not
 * available right now, it will sleep until it can get it.
 *
 * The mutex must later on be released by the same task that
 * acquired it. Recursive locking is not allowed. The task
 * may not exit without first unlocking the mutex. Also, kernel
 * memory where the mutex resides mutex must not be freed with
 * the mutex still locked. The mutex must first be initialized
 * (or statically defined) before it can be locked. memset()-ing
 * the mutex to 0 is not allowed.
 *
 * ( The CONFIG_DEBUG_MUTEXES .config option turns on debugging
 *   checks that will enforce the restrictions and will also do
 *   deadlock debugging. )
 *
 * This function is similar to (but not equivalent to) down().
 */
void inline fastcall __sched mutex_lock(struct mutex *lock)
{
	might_sleep();
	/*
	 * The locking fastpath is the 1->0 transition from
	 * 'unlocked' into 'locked' state.
	 */
	__mutex_fastpath_lock(&lock->count, __mutex_lock_slowpath);
}

EXPORT_SYMBOL(mutex_lock);
#endif

static void fastcall noinline __sched
__mutex_unlock_slowpath(atomic_t *lock_count);

/***
 * mutex_unlock - release the mutex
 * @lock: the mutex to be released
 *
 * Unlock a mutex that has been locked by this task previously.
 *
 * This function must not be used in interrupt context. Unlocking
 * of a not locked mutex is not allowed.
 *
 * This function is similar to (but not equivalent to) up().
 */
void fastcall __sched mutex_unlock(struct mutex *lock)
{
	/*
	 * The unlocking fastpath is the 0->1 transition from 'locked'
	 * into 'unlocked' state:
	 */
	__mutex_fastpath_unlock(&lock->count, __mutex_unlock_slowpath);
}

EXPORT_SYMBOL(mutex_unlock);

/*
 * Lock a mutex (possibly interruptible), slowpath:
 */
static inline int __sched
__mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
	       	unsigned long ip)
{
	struct task_struct *task = current;
	struct mutex_waiter waiter;
	unsigned int old_val;
	unsigned long flags;

	spin_lock_mutex(&lock->wait_lock, flags);

	debug_mutex_lock_common(lock, &waiter);
	mutex_acquire(&lock->dep_map, subclass, 0, ip);
	debug_mutex_add_waiter(lock, &waiter, task_thread_info(task));

	/* add waiting tasks to the end of the waitqueue (FIFO): */
	list_add_tail(&waiter.list, &lock->wait_list);
	waiter.task = task;

	old_val = atomic_xchg(&lock->count, -1);
	if (old_val == 1)
		goto done;

	lock_contended(&lock->dep_map, ip);

	for (;;) {
		/*
		 * Lets try to take the lock again - this is needed even if
		 * we get here for the first time (shortly after failing to
		 * acquire the lock), to make sure that we get a wakeup once
		 * it's unlocked. Later on, if we sleep, this is the
		 * operation that gives us the lock. We xchg it to -1, so
		 * that when we release the lock, we properly wake up the
		 * other waiters:
		 */
		old_val = atomic_xchg(&lock->count, -1);
		if (old_val == 1)
			break;

		/*
		 * got a signal? (This code gets eliminated in the
		 * TASK_UNINTERRUPTIBLE case.)
		 */
		if (unlikely((state == TASK_INTERRUPTIBLE &&
					signal_pending(task)) ||
			      (state == TASK_KILLABLE &&
					fatal_signal_pending(task)))) {
			mutex_remove_waiter(lock, &waiter,
					    task_thread_info(task));
			mutex_release(&lock->dep_map, 1, ip);
			spin_unlock_mutex(&lock->wait_lock, flags);

			debug_mutex_free_waiter(&waiter);
			return -EINTR;
		}
		__set_task_state(task, state);

		/* didnt get the lock, go to sleep: */
		spin_unlock_mutex(&lock->wait_lock, flags);
		schedule();
		spin_lock_mutex(&lock->wait_lock, flags);
	}

done:
	lock_acquired(&lock->dep_map);
	/* got the lock - rejoice! */
	mutex_remove_waiter(lock, &waiter, task_thread_info(task));
	debug_mutex_set_owner(lock, task_thread_info(task));

	/* set it to 0 if there are no waiters left: */
	if (likely(list_empty(&lock->wait_list)))
		atomic_set(&lock->count, 0);

	spin_unlock_mutex(&lock->wait_lock, flags);

	debug_mutex_free_waiter(&waiter);

	return 0;
}

#ifdef CONFIG_DEBUG_LOCK_ALLOC
void __sched
mutex_lock_nested(struct mutex *lock, unsigned int subclass)
{
	might_sleep();
	__mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, subclass, _RET_IP_);
}

EXPORT_SYMBOL_GPL(mutex_lock_nested);

int __sched
mutex_lock_killable_nested(struct mutex *lock, unsigned int subclass)
{
	might_sleep();
	return __mutex_lock_common(lock, TASK_KILLABLE, subclass, _RET_IP_);
}
EXPORT_SYMBOL_GPL(mutex_lock_killable_nested);

int __sched
mutex_lock_interruptible_nested(struct mutex *lock, unsigned int subclass)
{
	might_sleep();
	return __mutex_lock_common(lock, TASK_INTERRUPTIBLE, subclass, _RET_IP_);
}

EXPORT_SYMBOL_GPL(mutex_lock_interruptible_nested);
#endif

/*
 * Release the lock, slowpath:
 */
static fastcall inline void
__mutex_unlock_common_slowpath(atomic_t *lock_count, int nested)
{
	struct mutex *lock = container_of(lock_count, struct mutex, count);
	unsigned long flags;

	spin_lock_mutex(&lock->wait_lock, flags);
	mutex_release(&lock->dep_map, nested, _RET_IP_);
	debug_mutex_unlock(lock);

	/*
	 * some architectures leave the lock unlocked in the fastpath failure
	 * case, others need to leave it locked. In the later case we have to
	 * unlock it here
	 */
	if (__mutex_slowpath_needs_to_unlock())
		atomic_set(&lock->count, 1);

	if (!list_empty(&lock->wait_list)) {
		/* get the first entry from the wait-list: */
		struct mutex_waiter *waiter =
				list_entry(lock->wait_list.next,
					   struct mutex_waiter, list);

		debug_mutex_wake_waiter(lock, waiter);

		wake_up_process(waiter->task);
	}

	debug_mutex_clear_owner(lock);

	spin_unlock_mutex(&lock->wait_lock, flags);
}

/*
 * Release the lock, slowpath:
 */
static fastcall noinline void
__mutex_unlock_slowpath(atomic_t *lock_count)
{
	__mutex_unlock_common_slowpath(lock_count, 1);
}

#ifndef CONFIG_DEBUG_LOCK_ALLOC
/*
 * Here come the less common (and hence less performance-critical) APIs:
 * mutex_lock_interruptible() and mutex_trylock().
 */
static int fastcall noinline __sched
__mutex_lock_killable_slowpath(atomic_t *lock_count);

static noinline int fastcall __sched
__mutex_lock_interruptible_slowpath(atomic_t *lock_count);

/***
 * mutex_lock_interruptible - acquire the mutex, interruptable
 * @lock: the mutex to be acquired
 *
 * Lock the mutex like mutex_lock(), and return 0 if the mutex has
 * been acquired or sleep until the mutex becomes available. If a
 * signal arrives while waiting for the lock then this function
 * returns -EINTR.
 *
 * This function is similar to (but not equivalent to) down_interruptible().
 */
int fastcall __sched mutex_lock_interruptible(struct mutex *lock)
{
	might_sleep();
	return __mutex_fastpath_lock_retval
			(&lock->count, __mutex_lock_interruptible_slowpath);
}

EXPORT_SYMBOL(mutex_lock_interruptible);

int fastcall __sched mutex_lock_killable(struct mutex *lock)
{
	might_sleep();
	return __mutex_fastpath_lock_retval
			(&lock->count, __mutex_lock_killable_slowpath);
}
EXPORT_SYMBOL(mutex_lock_killable);

static void fastcall noinline __sched
__mutex_lock_slowpath(atomic_t *lock_count)
{
	struct mutex *lock = container_of(lock_count, struct mutex, count);

	__mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, 0, _RET_IP_);
}

static int fastcall noinline __sched
__mutex_lock_killable_slowpath(atomic_t *lock_count)
{
	struct mutex *lock = container_of(lock_count, struct mutex, count);

	return __mutex_lock_common(lock, TASK_KILLABLE, 0, _RET_IP_);
}

static noinline int fastcall __sched
__mutex_lock_interruptible_slowpath(atomic_t *lock_count)
{
	struct mutex *lock = container_of(lock_count, struct mutex, count);

	return __mutex_lock_common(lock, TASK_INTERRUPTIBLE, 0, _RET_IP_);
}
#endif

/*
 * Spinlock based trylock, we take the spinlock and check whether we
 * can get the lock:
 */
static inline int __mutex_trylock_slowpath(atomic_t *lock_count)
{
	struct mutex *lock = container_of(lock_count, struct mutex, count);
	unsigned long flags;
	int prev;

	spin_lock_mutex(&lock->wait_lock, flags);

	prev = atomic_xchg(&lock->count, -1);
	if (likely(prev == 1)) {
		debug_mutex_set_owner(lock, current_thread_info());
		mutex_acquire(&lock->dep_map, 0, 1, _RET_IP_);
	}
	/* Set it back to 0 if there are no waiters: */
	if (likely(list_empty(&lock->wait_list)))
		atomic_set(&lock->count, 0);

	spin_unlock_mutex(&lock->wait_lock, flags);

	return prev == 1;
}

/***
 * mutex_trylock - try acquire the mutex, without waiting
 * @lock: the mutex to be acquired
 *
 * Try to acquire the mutex atomically. Returns 1 if the mutex
 * has been acquired successfully, and 0 on contention.
 *
 * NOTE: this function follows the spin_trylock() convention, so
 * it is negated to the down_trylock() return values! Be careful
 * about this when converting semaphore users to mutexes.
 *
 * This function must not be used in interrupt context. The
 * mutex must be released by the same task that acquired it.
 */
int fastcall __sched mutex_trylock(struct mutex *lock)
{
	return __mutex_fastpath_trylock(&lock->count,
					__mutex_trylock_slowpath);
}

EXPORT_SYMBOL(mutex_trylock);
Commit	Line	Data
6053ee3b IM	1	/*
	2	* kernel/mutex.c
	3	*
	4	* Mutexes: blocking mutual exclusion locks
	5	*
	6	* Started by Ingo Molnar:
	7	*
	8	* Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
	9	*
	10	* Many thanks to Arjan van de Ven, Thomas Gleixner, Steven Rostedt and
	11	* David Howells for suggestions and improvements.
	12	*
	13	* Also see Documentation/mutex-design.txt.
	14	*/
	15	#include <linux/mutex.h>
	16	#include <linux/sched.h>
	17	#include <linux/module.h>
	18	#include <linux/spinlock.h>
	19	#include <linux/interrupt.h>
9a11b49a	20	#include <linux/debug_locks.h>
6053ee3b IM	21
	22	/*
	23	* In the DEBUG case we are using the "NULL fastpath" for mutexes,
	24	* which forces all calls into the slowpath:
	25	*/
	26	#ifdef CONFIG_DEBUG_MUTEXES
	27	# include "mutex-debug.h"
	28	# include <asm-generic/mutex-null.h>
	29	#else
	30	# include "mutex.h"
	31	# include <asm/mutex.h>
	32	#endif
	33
	34	/***
	35	* mutex_init - initialize the mutex
	36	* @lock: the mutex to be initialized
	37	*
	38	* Initialize the mutex to unlocked state.
	39	*
	40	* It is not allowed to initialize an already locked mutex.
	41	*/
ef5d4707 IM	42	void
ef5d4707 IM	43	__mutex_init(struct mutex lock, const char name, struct lock_class_key *key)
6053ee3b IM	44	{
	45	atomic_set(&lock->count, 1);
	46	spin_lock_init(&lock->wait_lock);
	47	INIT_LIST_HEAD(&lock->wait_list);
	48
ef5d4707	49	debug_mutex_init(lock, name, key);
6053ee3b IM	50	}
	51
	52	EXPORT_SYMBOL(__mutex_init);
	53
e4564f79	54	#ifndef CONFIG_DEBUG_LOCK_ALLOC
6053ee3b IM	55	/*
	56	* We split the mutex lock/unlock logic into separate fastpath and
	57	* slowpath functions, to reduce the register pressure on the fastpath.
	58	* We also put the fastpath first in the kernel image, to make sure the
	59	* branch is predicted by the CPU as default-untaken.
	60	*/
	61	static void fastcall noinline __sched
9a11b49a	62	__mutex_lock_slowpath(atomic_t *lock_count);
6053ee3b IM	63
	64	/***
	65	* mutex_lock - acquire the mutex
	66	* @lock: the mutex to be acquired
	67	*
	68	* Lock the mutex exclusively for this task. If the mutex is not
	69	* available right now, it will sleep until it can get it.
	70	*
	71	* The mutex must later on be released by the same task that
	72	* acquired it. Recursive locking is not allowed. The task
	73	* may not exit without first unlocking the mutex. Also, kernel
	74	* memory where the mutex resides mutex must not be freed with
	75	* the mutex still locked. The mutex must first be initialized
	76	* (or statically defined) before it can be locked. memset()-ing
	77	* the mutex to 0 is not allowed.
	78	*
	79	* ( The CONFIG_DEBUG_MUTEXES .config option turns on debugging
	80	* checks that will enforce the restrictions and will also do
	81	* deadlock debugging. )
	82	*
	83	* This function is similar to (but not equivalent to) down().
	84	*/
9a11b49a	85	void inline fastcall __sched mutex_lock(struct mutex *lock)
6053ee3b	86	{
c544bdb1	87	might_sleep();
6053ee3b IM	88	/*
	89	* The locking fastpath is the 1->0 transition from
	90	* 'unlocked' into 'locked' state.
6053ee3b IM	91	*/
	92	__mutex_fastpath_lock(&lock->count, __mutex_lock_slowpath);
	93	}
	94
	95	EXPORT_SYMBOL(mutex_lock);
e4564f79	96	#endif
6053ee3b IM	97
6053ee3b IM	98	static void fastcall noinline __sched
9a11b49a	99	__mutex_unlock_slowpath(atomic_t *lock_count);
6053ee3b IM	100
	101	/***
	102	* mutex_unlock - release the mutex
	103	* @lock: the mutex to be released
	104	*
	105	* Unlock a mutex that has been locked by this task previously.
	106	*
	107	* This function must not be used in interrupt context. Unlocking
	108	* of a not locked mutex is not allowed.
	109	*
	110	* This function is similar to (but not equivalent to) up().
	111	*/
	112	void fastcall __sched mutex_unlock(struct mutex *lock)
	113	{
	114	/*
	115	* The unlocking fastpath is the 0->1 transition from 'locked'
	116	* into 'unlocked' state:
6053ee3b IM	117	*/
	118	__mutex_fastpath_unlock(&lock->count, __mutex_unlock_slowpath);
	119	}
	120
	121	EXPORT_SYMBOL(mutex_unlock);
	122
	123	/*
	124	* Lock a mutex (possibly interruptible), slowpath:
	125	*/
	126	static inline int __sched
e4564f79 PZ	127	__mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
e4564f79 PZ	128	unsigned long ip)
6053ee3b IM	129	{
	130	struct task_struct *task = current;
	131	struct mutex_waiter waiter;
	132	unsigned int old_val;
1fb00c6c	133	unsigned long flags;
6053ee3b	134
1fb00c6c	135	spin_lock_mutex(&lock->wait_lock, flags);
6053ee3b	136
9a11b49a	137	debug_mutex_lock_common(lock, &waiter);
e4564f79	138	mutex_acquire(&lock->dep_map, subclass, 0, ip);
c9f4f06d	139	debug_mutex_add_waiter(lock, &waiter, task_thread_info(task));
6053ee3b IM	140
	141	/* add waiting tasks to the end of the waitqueue (FIFO): */
	142	list_add_tail(&waiter.list, &lock->wait_list);
	143	waiter.task = task;
	144
4fe87745 PZ	145	old_val = atomic_xchg(&lock->count, -1);
	146	if (old_val == 1)
	147	goto done;
	148
e4564f79	149	lock_contended(&lock->dep_map, ip);
4fe87745	150
6053ee3b IM	151	for (;;) {
	152	/*
	153	* Lets try to take the lock again - this is needed even if
	154	* we get here for the first time (shortly after failing to
	155	* acquire the lock), to make sure that we get a wakeup once
	156	* it's unlocked. Later on, if we sleep, this is the
	157	* operation that gives us the lock. We xchg it to -1, so
	158	* that when we release the lock, we properly wake up the
	159	* other waiters:
	160	*/
	161	old_val = atomic_xchg(&lock->count, -1);
	162	if (old_val == 1)
	163	break;
	164
	165	/*
	166	* got a signal? (This code gets eliminated in the
	167	* TASK_UNINTERRUPTIBLE case.)
	168	*/
ad776537 LH	169	if (unlikely((state == TASK_INTERRUPTIBLE &&
	170	signal_pending(task)) \|\|
	171	(state == TASK_KILLABLE &&
	172	fatal_signal_pending(task)))) {
	173	mutex_remove_waiter(lock, &waiter,
	174	task_thread_info(task));
e4564f79	175	mutex_release(&lock->dep_map, 1, ip);
1fb00c6c	176	spin_unlock_mutex(&lock->wait_lock, flags);
6053ee3b IM	177
	178	debug_mutex_free_waiter(&waiter);
	179	return -EINTR;
	180	}
	181	__set_task_state(task, state);
	182
	183	/* didnt get the lock, go to sleep: */
1fb00c6c	184	spin_unlock_mutex(&lock->wait_lock, flags);
6053ee3b	185	schedule();
1fb00c6c	186	spin_lock_mutex(&lock->wait_lock, flags);
6053ee3b IM	187	}
6053ee3b IM	188
4fe87745	189	done:
96645678	190	lock_acquired(&lock->dep_map);
6053ee3b	191	/* got the lock - rejoice! */
c9f4f06d RZ	192	mutex_remove_waiter(lock, &waiter, task_thread_info(task));
c9f4f06d RZ	193	debug_mutex_set_owner(lock, task_thread_info(task));
6053ee3b IM	194
	195	/* set it to 0 if there are no waiters left: */
	196	if (likely(list_empty(&lock->wait_list)))
	197	atomic_set(&lock->count, 0);
	198
1fb00c6c	199	spin_unlock_mutex(&lock->wait_lock, flags);
6053ee3b IM	200
	201	debug_mutex_free_waiter(&waiter);
	202
6053ee3b IM	203	return 0;
	204	}
	205
ef5d4707 IM	206	#ifdef CONFIG_DEBUG_LOCK_ALLOC
	207	void __sched
	208	mutex_lock_nested(struct mutex *lock, unsigned int subclass)
	209	{
	210	might_sleep();
e4564f79	211	__mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, subclass, _RET_IP_);
ef5d4707 IM	212	}
	213
	214	EXPORT_SYMBOL_GPL(mutex_lock_nested);
d63a5a74	215
ad776537 LH	216	int __sched
	217	mutex_lock_killable_nested(struct mutex *lock, unsigned int subclass)
	218	{
	219	might_sleep();
	220	return __mutex_lock_common(lock, TASK_KILLABLE, subclass, _RET_IP_);
	221	}
	222	EXPORT_SYMBOL_GPL(mutex_lock_killable_nested);
	223
d63a5a74 N	224	int __sched
	225	mutex_lock_interruptible_nested(struct mutex *lock, unsigned int subclass)
	226	{
	227	might_sleep();
e4564f79	228	return __mutex_lock_common(lock, TASK_INTERRUPTIBLE, subclass, _RET_IP_);
d63a5a74 N	229	}
	230
	231	EXPORT_SYMBOL_GPL(mutex_lock_interruptible_nested);
ef5d4707 IM	232	#endif
ef5d4707 IM	233
6053ee3b IM	234	/*
	235	* Release the lock, slowpath:
	236	*/
9a11b49a	237	static fastcall inline void
ef5d4707	238	__mutex_unlock_common_slowpath(atomic_t *lock_count, int nested)
6053ee3b	239	{
02706647	240	struct mutex *lock = container_of(lock_count, struct mutex, count);
1fb00c6c	241	unsigned long flags;
6053ee3b	242
1fb00c6c	243	spin_lock_mutex(&lock->wait_lock, flags);
ef5d4707	244	mutex_release(&lock->dep_map, nested, _RET_IP_);
9a11b49a	245	debug_mutex_unlock(lock);
6053ee3b IM	246
	247	/*
	248	* some architectures leave the lock unlocked in the fastpath failure
	249	* case, others need to leave it locked. In the later case we have to
	250	* unlock it here
	251	*/
	252	if (__mutex_slowpath_needs_to_unlock())
	253	atomic_set(&lock->count, 1);
	254
6053ee3b IM	255	if (!list_empty(&lock->wait_list)) {
	256	/* get the first entry from the wait-list: */
	257	struct mutex_waiter *waiter =
	258	list_entry(lock->wait_list.next,
	259	struct mutex_waiter, list);
	260
	261	debug_mutex_wake_waiter(lock, waiter);
	262
	263	wake_up_process(waiter->task);
	264	}
	265
	266	debug_mutex_clear_owner(lock);
	267
1fb00c6c	268	spin_unlock_mutex(&lock->wait_lock, flags);
6053ee3b IM	269	}
6053ee3b IM	270
9a11b49a IM	271	/*
	272	* Release the lock, slowpath:
	273	*/
	274	static fastcall noinline void
	275	__mutex_unlock_slowpath(atomic_t *lock_count)
	276	{
ef5d4707	277	__mutex_unlock_common_slowpath(lock_count, 1);
9a11b49a IM	278	}
9a11b49a IM	279
e4564f79	280	#ifndef CONFIG_DEBUG_LOCK_ALLOC
6053ee3b IM	281	/*
	282	* Here come the less common (and hence less performance-critical) APIs:
	283	* mutex_lock_interruptible() and mutex_trylock().
	284	*/
	285	static int fastcall noinline __sched
ad776537 LH	286	__mutex_lock_killable_slowpath(atomic_t *lock_count);
	287
	288	static noinline int fastcall __sched
9a11b49a	289	__mutex_lock_interruptible_slowpath(atomic_t *lock_count);
6053ee3b IM	290
	291	/***
	292	* mutex_lock_interruptible - acquire the mutex, interruptable
	293	* @lock: the mutex to be acquired
	294	*
	295	* Lock the mutex like mutex_lock(), and return 0 if the mutex has
	296	* been acquired or sleep until the mutex becomes available. If a
	297	* signal arrives while waiting for the lock then this function
	298	* returns -EINTR.
	299	*
	300	* This function is similar to (but not equivalent to) down_interruptible().
	301	*/
	302	int fastcall __sched mutex_lock_interruptible(struct mutex *lock)
	303	{
c544bdb1	304	might_sleep();
6053ee3b IM	305	return __mutex_fastpath_lock_retval
	306	(&lock->count, __mutex_lock_interruptible_slowpath);
	307	}
	308
	309	EXPORT_SYMBOL(mutex_lock_interruptible);
	310
ad776537 LH	311	int fastcall __sched mutex_lock_killable(struct mutex *lock)
	312	{
	313	might_sleep();
	314	return __mutex_fastpath_lock_retval
	315	(&lock->count, __mutex_lock_killable_slowpath);
	316	}
	317	EXPORT_SYMBOL(mutex_lock_killable);
	318
e4564f79 PZ	319	static void fastcall noinline __sched
	320	__mutex_lock_slowpath(atomic_t *lock_count)
	321	{
	322	struct mutex *lock = container_of(lock_count, struct mutex, count);
	323
	324	__mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, 0, _RET_IP_);
	325	}
	326
6053ee3b	327	static int fastcall noinline __sched
ad776537 LH	328	__mutex_lock_killable_slowpath(atomic_t *lock_count)
	329	{
	330	struct mutex *lock = container_of(lock_count, struct mutex, count);
	331
	332	return __mutex_lock_common(lock, TASK_KILLABLE, 0, _RET_IP_);
	333	}
	334
	335	static noinline int fastcall __sched
9a11b49a	336	__mutex_lock_interruptible_slowpath(atomic_t *lock_count)
6053ee3b IM	337	{
	338	struct mutex *lock = container_of(lock_count, struct mutex, count);
	339
e4564f79	340	return __mutex_lock_common(lock, TASK_INTERRUPTIBLE, 0, _RET_IP_);
6053ee3b	341	}
e4564f79	342	#endif
6053ee3b IM	343
	344	/*
	345	* Spinlock based trylock, we take the spinlock and check whether we
	346	* can get the lock:
	347	*/
	348	static inline int __mutex_trylock_slowpath(atomic_t *lock_count)
	349	{
	350	struct mutex *lock = container_of(lock_count, struct mutex, count);
1fb00c6c	351	unsigned long flags;
6053ee3b IM	352	int prev;
6053ee3b IM	353
1fb00c6c	354	spin_lock_mutex(&lock->wait_lock, flags);
6053ee3b IM	355
6053ee3b IM	356	prev = atomic_xchg(&lock->count, -1);
ef5d4707	357	if (likely(prev == 1)) {
9a11b49a	358	debug_mutex_set_owner(lock, current_thread_info());
ef5d4707 IM	359	mutex_acquire(&lock->dep_map, 0, 1, _RET_IP_);
ef5d4707 IM	360	}
6053ee3b IM	361	/* Set it back to 0 if there are no waiters: */
	362	if (likely(list_empty(&lock->wait_list)))
	363	atomic_set(&lock->count, 0);
	364
1fb00c6c	365	spin_unlock_mutex(&lock->wait_lock, flags);
6053ee3b IM	366
	367	return prev == 1;
	368	}
	369
	370	/***
	371	* mutex_trylock - try acquire the mutex, without waiting
	372	* @lock: the mutex to be acquired
	373	*
	374	* Try to acquire the mutex atomically. Returns 1 if the mutex
	375	* has been acquired successfully, and 0 on contention.
	376	*
	377	* NOTE: this function follows the spin_trylock() convention, so
	378	* it is negated to the down_trylock() return values! Be careful
	379	* about this when converting semaphore users to mutexes.
	380	*
	381	* This function must not be used in interrupt context. The
	382	* mutex must be released by the same task that acquired it.
	383	*/
9cebb552	384	int fastcall __sched mutex_trylock(struct mutex *lock)
6053ee3b IM	385	{
	386	return __mutex_fastpath_trylock(&lock->count,
	387	__mutex_trylock_slowpath);
	388	}
	389
	390	EXPORT_SYMBOL(mutex_trylock);