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Commit e4a683c8 authored by Jerome Marchand's avatar Jerome Marchand Committed by Jens Axboe
Browse files

kref: add kref_test_and_get 



Add kref_test_and_get() function, which atomically add a reference only if
refcount is not zero. This prevent to add a reference to an object that is
already being removed.

Signed-off-by: default avatarJerome Marchand <jmarchan@redhat.com>
Cc: stable@kernel.org
Signed-off-by: default avatarJens Axboe <jaxboe@fusionio.com>
parent a6e8dc46

include/linux/kref.h

+1 −0
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ struct kref { 


void kref_init(struct kref *kref);

void kref_get(struct kref *kref);

int kref_test_and_get(struct kref *kref);

int kref_put(struct kref *kref, void (*release) (struct kref *kref));



#endif /* _KREF_H_ */

lib/kref.c

+12 −0
Original line number Diff line number Diff line
@@ -36,6 +36,18 @@ void kref_get(struct kref *kref) 
	smp_mb__after_atomic_inc();

}



/**

 * kref_test_and_get - increment refcount for object only if refcount is not

 * zero.

 * @kref: object.

 *

 * Return non-zero if the refcount was incremented, 0 otherwise

 */

int kref_test_and_get(struct kref *kref)

{

	return atomic_inc_not_zero(&kref->refcount);

}



/**

 * kref_put - decrement refcount for object.

 * @kref: object.