SUNRPC: Refactor rpc_sleep_on()

rpc_sleep_on() does not need to set the task->tk_callback under the
queue lock, so move that out.
Also refactor the check for whether the task is active.
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

net/sunrpc/sched.c

@@ -362,7 +362,6 @@ static void rpc_make_runnable(struct workqueue_struct *wq,
  */
 static void __rpc_sleep_on_priority(struct rpc_wait_queue *q,
 		struct rpc_task *task,
-		rpc_action action,
 		unsigned char queue_priority)
 {
 	dprintk("RPC: %5u sleep_on(queue \"%s\" time %lu)\n",
@@ -372,27 +371,39 @@ static void __rpc_sleep_on_priority(struct rpc_wait_queue *q,
 
 	__rpc_add_wait_queue(q, task, queue_priority);
 
-	WARN_ON_ONCE(task->tk_callback != NULL);
-	task->tk_callback = action;
 	__rpc_add_timer(q, task);
 }
 
-void rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
-				rpc_action action)
+static void rpc_set_tk_callback(struct rpc_task *task, rpc_action action)
+{
+	if (action && !WARN_ON_ONCE(task->tk_callback != NULL))
+		task->tk_callback = action;
+}
+
+static bool rpc_sleep_check_activated(struct rpc_task *task)
 {
 	/* We shouldn't ever put an inactive task to sleep */
-	WARN_ON_ONCE(!RPC_IS_ACTIVATED(task));
-	if (!RPC_IS_ACTIVATED(task)) {
+	if (WARN_ON_ONCE(!RPC_IS_ACTIVATED(task))) {
 		task->tk_status = -EIO;
 		rpc_put_task_async(task);
-		return;
+		return false;
 	}
+	return true;
+}
+
+void rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
+				rpc_action action)
+{
+	if (!rpc_sleep_check_activated(task))
+		return;
+
+	rpc_set_tk_callback(task, action);
 
 	/*
 	 * Protect the queue operations.
 	 */
 	spin_lock_bh(&q->lock);
-	__rpc_sleep_on_priority(q, task, action, task->tk_priority);
+	__rpc_sleep_on_priority(q, task, task->tk_priority);
 	spin_unlock_bh(&q->lock);
 }
 EXPORT_SYMBOL_GPL(rpc_sleep_on);
@@ -400,19 +411,16 @@ EXPORT_SYMBOL_GPL(rpc_sleep_on);
 void rpc_sleep_on_priority(struct rpc_wait_queue *q, struct rpc_task *task,
 		rpc_action action, int priority)
 {
-	/* We shouldn't ever put an inactive task to sleep */
-	WARN_ON_ONCE(!RPC_IS_ACTIVATED(task));
-	if (!RPC_IS_ACTIVATED(task)) {
-		task->tk_status = -EIO;
-		rpc_put_task_async(task);
+	if (!rpc_sleep_check_activated(task))
 		return;
-	}
+
+	rpc_set_tk_callback(task, action);
 
 	/*
 	 * Protect the queue operations.
 	 */
 	spin_lock_bh(&q->lock);
-	__rpc_sleep_on_priority(q, task, action, priority - RPC_PRIORITY_LOW);
+	__rpc_sleep_on_priority(q, task, priority - RPC_PRIORITY_LOW);
 	spin_unlock_bh(&q->lock);
 }
 EXPORT_SYMBOL_GPL(rpc_sleep_on_priority);