Commit 8ad5db8a authored by Al Viro's avatar Al Viro
Browse files

introduce kref_put_mutex() 



equivalent of
	mutex_lock(mutex);
	if (!kref_put(kref, release))
		mutex_unlock(mutex);

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 934ad4c2

include/linux/kref.h

+18 −0
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ 
#include <linux/bug.h>

#include <linux/atomic.h>

#include <linux/kernel.h>

#include <linux/mutex.h>



struct kref {

	atomic_t refcount;
@@ -93,4 +94,21 @@ static inline int kref_put(struct kref *kref, void (*release)(struct kref *kref) 
{

	return kref_sub(kref, 1, release);

}



static inline int kref_put_mutex(struct kref *kref,

				 void (*release)(struct kref *kref),

				 struct mutex *lock)

{

	WARN_ON(release == NULL);

        if (unlikely(!atomic_add_unless(&kref->refcount, -1, 1))) {

		mutex_lock(lock);

		if (unlikely(!atomic_dec_and_test(&kref->refcount))) {

			mutex_unlock(lock);

			return 0;

		}

		release(kref);

		return 1;

	}

	return 0;

}

#endif /* _KREF_H_ */