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

@@ -44,57 +44,49 @@ static inline void kref_get(struct kref *kref)
 }
 
 /**
- * kref_put - decrement refcount for object.
+ * kref_sub - subtract a number of refcounts for object.
  * @kref: object.
+ * @count: Number of recounts to subtract.
  * @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().
+ * Subtract @count from 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))
+static inline int kref_sub(struct kref *kref, unsigned int count,
+	     void (*release)(struct kref *kref))
 {
 	WARN_ON(release == NULL);
 	WARN_ON(release == (void (*)(struct kref *))kfree);
 
-	if (atomic_dec_and_test(&kref->refcount)) {
+	if (atomic_sub_and_test((int) count, &kref->refcount)) {
 		release(kref);
 		return 1;
 	}
 	return 0;
 }
 
-
 /**
- * kref_sub - subtract a number of refcounts for object.
+ * kref_put - decrement refcount for object.
  * @kref: object.
- * @count: Number of recounts to subtract.
  * @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.
  *
- * Subtract @count from the refcount, and if 0, call release().
+ * 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_sub(struct kref *kref, unsigned int count,
-	     void (*release)(struct kref *kref))
+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_sub_and_test((int) count, &kref->refcount)) {
-		release(kref);
-		return 1;
-	}
-	return 0;
+	return kref_sub(kref, 1, release);
 }
 #endif /* _KREF_H_ */