kref: Implement kref_put in terms of kref_sub

Less lines of code is better.

Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

include/linux/kref.h

@@ -43,33 +43,6 @@ static inline void kref_get(struct kref *kref)
 	smp_mb__after_atomic_inc();
 }
 
-/**
- * kref_put - decrement refcount for object.
- * @kref: object.
- * @release: pointer to the function that will clean up the object when the
- *	     last reference to the object is released.
- *	     This pointer is required, and it is not acceptable to pass kfree
- *	     in as this function.
- *
- * Decrement the refcount, and if 0, call release().
- * Return 1 if the object was removed, otherwise return 0.  Beware, if this
- * function returns 0, you still can not count on the kref from remaining in
- * memory.  Only use the return value if you want to see if the kref is now
- * gone, not present.
- */
-static inline int kref_put(struct kref *kref, void (*release)(struct kref *kref))
-{
-	WARN_ON(release == NULL);
-	WARN_ON(release == (void (*)(struct kref *))kfree);
-
-	if (atomic_dec_and_test(&kref->refcount)) {
-		release(kref);
-		return 1;
-	}
-	return 0;
-}
-
-
 /**
  * kref_sub - subtract a number of refcounts for object.
  * @kref: object.
@@ -97,4 +70,23 @@ static inline int kref_sub(struct kref *kref, unsigned int count,
 	}
 	return 0;
 }
+
+/**
+ * kref_put - decrement refcount for object.
+ * @kref: object.
+ * @release: pointer to the function that will clean up the object when the
+ *	     last reference to the object is released.
+ *	     This pointer is required, and it is not acceptable to pass kfree
+ *	     in as this function.
+ *
+ * Decrement the refcount, and if 0, call release().
+ * Return 1 if the object was removed, otherwise return 0.  Beware, if this
+ * function returns 0, you still can not count on the kref from remaining in
+ * memory.  Only use the return value if you want to see if the kref is now
+ * gone, not present.
+ */
+static inline int kref_put(struct kref *kref, void (*release)(struct kref *kref))
+{
+	return kref_sub(kref, 1, release);
+}
 #endif /* _KREF_H_ */