net: vhost: replace magic number of lock annotation

Use the VHOST_NET_VQ_XXX as a subclass for mutex_lock_nested.
Signed-off-by: NTonghao Zhang <xiangxia.m.yue@gmail.com>
Acked-by: NJason Wang <jasowang@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/vhost/net.c

@@ -856,7 +856,7 @@ static void handle_tx(struct vhost_net *net)
 	struct vhost_virtqueue *vq = &nvq->vq;
 	struct socket *sock;
 
-	mutex_lock(&vq->mutex);
+	mutex_lock_nested(&vq->mutex, VHOST_NET_VQ_TX);
 	sock = vq->private_data;
 	if (!sock)
 		goto out;
@@ -921,7 +921,7 @@ static int vhost_net_rx_peek_head_len(struct vhost_net *net, struct sock *sk,
 		/* Flush batched heads first */
 		vhost_net_signal_used(rnvq);
 		/* Both tx vq and rx socket were polled here */
-		mutex_lock_nested(&tvq->mutex, 1);
+		mutex_lock_nested(&tvq->mutex, VHOST_NET_VQ_TX);
 		vhost_disable_notify(&net->dev, tvq);
 
 		preempt_disable();
@@ -1063,7 +1063,7 @@ static void handle_rx(struct vhost_net *net)
 	__virtio16 num_buffers;
 	int recv_pkts = 0;
 
-	mutex_lock_nested(&vq->mutex, 0);
+	mutex_lock_nested(&vq->mutex, VHOST_NET_VQ_RX);
 	sock = vq->private_data;
 	if (!sock)
 		goto out;