+static bool tcp_rtx_queue_empty_or_single_skb(const struct sock *sk)
+{
+ const struct rb_node *node = sk->tcp_rtx_queue.rb_node;
+
+ /* No skb in the rtx queue. */
+ if (!node)
+ return true;
+
+ /* Only one skb in rtx queue. */
+ return !node->rb_left && !node->rb_right;
+}
+