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introduce kref_put_mutex()

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

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2012-08-17 20:10:46 -04:00
parent 934ad4c235
commit 8ad5db8a8d
1 changed files with 18 additions and 0 deletions
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18
include/linux/kref.h
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@ -18,6 +18,7 @@
#include <linux/bug.h> #include <linux/bug.h>
#include <linux/atomic.h> #include <linux/atomic.h>
#include <linux/kernel.h> #include <linux/kernel.h>
#include <linux/mutex.h>
struct kref { struct kref {
atomic_t refcount; 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); 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_ */ #endif /* _KREF_H_ */