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Commit a511e3f9 authored by Andrew Morton's avatar Andrew Morton Committed by Ingo Molnar
Browse files

mutex: add atomic_dec_and_mutex_lock(), fix 



include/linux/mutex.h:136: warning: 'mutex_lock' declared inline after being called
 include/linux/mutex.h:136: warning: previous declaration of 'mutex_lock' was here

uninline it.

[ Impact: clean up and uninline, address compiler warning ]

Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Eric Paris <eparis@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <200904292318.n3TNIsi6028340@imap1.linux-foundation.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 23b94b96

include/linux/mutex.h

+1 −23
Original line number Diff line number Diff line
@@ -150,28 +150,6 @@ extern int __must_check mutex_lock_killable(struct mutex *lock); 
 */

extern int mutex_trylock(struct mutex *lock);

extern void mutex_unlock(struct mutex *lock);



/**

 * atomic_dec_and_mutex_lock - return holding mutex if we dec to 0

 * @cnt: the atomic which we are to dec

 * @lock: the mutex to return holding if we dec to 0

 *

 * return true and hold lock if we dec to 0, return false otherwise

 */

static inline int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock)

{

	/* dec if we can't possibly hit 0 */

	if (atomic_add_unless(cnt, -1, 1))

		return 0;

	/* we might hit 0, so take the lock */

	mutex_lock(lock);

	if (!atomic_dec_and_test(cnt)) {

		/* when we actually did the dec, we didn't hit 0 */

		mutex_unlock(lock);

		return 0;

	}

	/* we hit 0, and we hold the lock */

	return 1;

}

extern int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock);



#endif

kernel/mutex.c

+24 −1
Original line number Diff line number Diff line
@@ -471,5 +471,28 @@ int __sched mutex_trylock(struct mutex *lock) 


	return ret;

}



EXPORT_SYMBOL(mutex_trylock);



/**

 * atomic_dec_and_mutex_lock - return holding mutex if we dec to 0

 * @cnt: the atomic which we are to dec

 * @lock: the mutex to return holding if we dec to 0

 *

 * return true and hold lock if we dec to 0, return false otherwise

 */

int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock)

{

	/* dec if we can't possibly hit 0 */

	if (atomic_add_unless(cnt, -1, 1))

		return 0;

	/* we might hit 0, so take the lock */

	mutex_lock(lock);

	if (!atomic_dec_and_test(cnt)) {

		/* when we actually did the dec, we didn't hit 0 */

		mutex_unlock(lock);

		return 0;

	}

	/* we hit 0, and we hold the lock */

	return 1;

}

EXPORT_SYMBOL(atomic_dec_and_mutex_lock);