audit_tree,rcu: Convert call_rcu(__put_tree) to kfree_rcu()

The rcu callback __put_tree() just calls a kfree(),
so we use kfree_rcu() instead of the call_rcu(__put_tree).
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Eric Paris <eparis@redhat.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>

kernel/audit_tree.c

@@ -93,16 +93,10 @@ static inline void get_tree(struct audit_tree *tree)
 	atomic_inc(&tree->count);
 }
 
-static void __put_tree(struct rcu_head *rcu)
-{
-	struct audit_tree *tree = container_of(rcu, struct audit_tree, head);
-	kfree(tree);
-}
-
 static inline void put_tree(struct audit_tree *tree)
 {
 	if (atomic_dec_and_test(&tree->count))
-		call_rcu(&tree->head, __put_tree);
+		kfree_rcu(tree, head);
 }
 
 /* to avoid bringing the entire thing in audit.h */