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Commit 450b1f6f authored by Andreas Gruenbacher's avatar Andreas Gruenbacher Committed by Bob Peterson
Browse files

lockref: Add lockref_put_not_zero 



Put a lockref unless the lockref is dead or its count would become zero.
This is the same as lockref_put_or_lock except that the lock is never
left held.

Signed-off-by: default avatarAndreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: default avatarBob Peterson <rpeterso@redhat.com>
parent e241e3f2

include/linux/lockref.h

+1 −0
Original line number Diff line number Diff line
@@ -37,6 +37,7 @@ struct lockref { 
extern void lockref_get(struct lockref *);

extern int lockref_put_return(struct lockref *);

extern int lockref_get_not_zero(struct lockref *);

extern int lockref_put_not_zero(struct lockref *);

extern int lockref_get_or_lock(struct lockref *);

extern int lockref_put_or_lock(struct lockref *);

lib/lockref.c

+28 −0
Original line number Diff line number Diff line
@@ -80,6 +80,34 @@ int lockref_get_not_zero(struct lockref *lockref) 
}

EXPORT_SYMBOL(lockref_get_not_zero);



/**

 * lockref_put_not_zero - Decrements count unless count <= 1 before decrement

 * @lockref: pointer to lockref structure

 * Return: 1 if count updated successfully or 0 if count would become zero

 */

int lockref_put_not_zero(struct lockref *lockref)

{

	int retval;



	CMPXCHG_LOOP(

		new.count--;

		if (old.count <= 1)

			return 0;

	,

		return 1;

	);



	spin_lock(&lockref->lock);

	retval = 0;

	if (lockref->count > 1) {

		lockref->count--;

		retval = 1;

	}

	spin_unlock(&lockref->lock);

	return retval;

}

EXPORT_SYMBOL(lockref_put_not_zero);



/**

 * lockref_get_or_lock - Increments count unless the count is 0 or dead

 * @lockref: pointer to lockref structure