rpc: add rpc_queue_empty function

Signed-off-by: NAlexandros Batsakis <batsakis@netapp.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

include/linux/sunrpc/sched.h

@@ -229,6 +229,7 @@ void		rpc_wake_up_queued_task(struct rpc_wait_queue *,
 void		rpc_wake_up(struct rpc_wait_queue *);
 struct rpc_task *rpc_wake_up_next(struct rpc_wait_queue *);
 void		rpc_wake_up_status(struct rpc_wait_queue *, int);
+int		rpc_queue_empty(struct rpc_wait_queue *);
 void		rpc_delay(struct rpc_task *, unsigned long);
 void *		rpc_malloc(struct rpc_task *, size_t);
 void		rpc_free(void *);

net/sunrpc/sched.c

@@ -384,6 +384,20 @@ static void rpc_wake_up_task_queue_locked(struct rpc_wait_queue *queue, struct r
 		__rpc_do_wake_up_task(queue, task);
 }
 
+/*
+ * Tests whether rpc queue is empty
+ */
+int rpc_queue_empty(struct rpc_wait_queue *queue)
+{
+	int res;
+
+	spin_lock_bh(&queue->lock);
+	res = queue->qlen;
+	spin_unlock_bh(&queue->lock);
+	return (res == 0);
+}
+EXPORT_SYMBOL_GPL(rpc_queue_empty);
+
 /*
  * Wake up a task on a specific queue
  */