1 files changed, 35 insertions, 4 deletions

diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
index f641e906f351..f992f9a216f0 100644
--- a/net/vmw_vsock/virtio_transport.c
+++ b/net/vmw_vsock/virtio_transport.c
@@ -208,6 +208,28 @@ out:
 		queue_work(virtio_vsock_workqueue, &vsock->rx_work);
 }
 
+/* Caller need to hold RCU for vsock.
+ * Returns 0 if the packet is successfully put on the vq.
+ */
+static int virtio_transport_send_skb_fast_path(struct virtio_vsock *vsock, struct sk_buff *skb)
+{
+	struct virtqueue *vq = vsock->vqs[VSOCK_VQ_TX];
+	int ret;
+
+	/* Inside RCU, can't sleep! */
+	ret = mutex_trylock(&vsock->tx_lock);
+	if (unlikely(ret == 0))
+		return -EBUSY;
+
+	ret = virtio_transport_send_skb(skb, vq, vsock);
+	if (ret == 0)
+		virtqueue_kick(vq);
+
+	mutex_unlock(&vsock->tx_lock);
+
+	return ret;
+}
+
 static int
 virtio_transport_send_pkt(struct sk_buff *skb)
 {
@@ -231,11 +253,20 @@ virtio_transport_send_pkt(struct sk_buff *skb)
 		goto out_rcu;
 	}
 
-	if (virtio_vsock_skb_reply(skb))
-		atomic_inc(&vsock->queued_replies);
+	/* If send_pkt_queue is empty, we can safely bypass this queue
+	 * because packet order is maintained and (try) to put the packet
+	 * on the virtqueue using virtio_transport_send_skb_fast_path.
+	 * If this fails we simply put the packet on the intermediate
+	 * queue and schedule the worker.
+	 */
+	if (!skb_queue_empty_lockless(&vsock->send_pkt_queue) ||
+	    virtio_transport_send_skb_fast_path(vsock, skb)) {
+		if (virtio_vsock_skb_reply(skb))
+			atomic_inc(&vsock->queued_replies);
 
-	virtio_vsock_skb_queue_tail(&vsock->send_pkt_queue, skb);
-	queue_work(virtio_vsock_workqueue, &vsock->send_pkt_work);
+		virtio_vsock_skb_queue_tail(&vsock->send_pkt_queue, skb);
+		queue_work(virtio_vsock_workqueue, &vsock->send_pkt_work);
+	}
 
 out_rcu:
 	rcu_read_unlock();