introduce kref_put_mutex()
equivalent of
mutex_lock(mutex);
if (!kref_put(kref, release))
mutex_unlock(mutex);
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/include/linux/kref.h b/include/linux/kref.h
index 9c07dce..65af688 100644
--- a/include/linux/kref.h
+++ b/include/linux/kref.h
@@ -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 @@
{
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_ */