virtio: populate network rings in the probe routine, not open

Since we want to reset the device to remove them, this is simpler
(device is reset for us on driver remove).

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

drivers/net/virtio_net.c

@@ -282,35 +282,16 @@ static int virtnet_open(struct net_device *dev)
 {
 	struct virtnet_info *vi = netdev_priv(dev);
 
-	try_fill_recv(vi);
-
-	/* If we didn't even get one input buffer, we're useless. */
-	if (vi->num == 0)
-		return -ENOMEM;
-
 	napi_enable(&vi->napi);
 	return 0;
 }
 
 static int virtnet_close(struct net_device *dev)
 {
 	struct virtnet_info *vi = netdev_priv(dev);
-	struct sk_buff *skb;
 
 	napi_disable(&vi->napi);
 
-	/* networking core has neutered skb_xmit_done/skb_recv_done, so don't
-	 * worry about races vs. get(). */
-	vi->rvq->vq_ops->shutdown(vi->rvq);
-	while ((skb = __skb_dequeue(&vi->recv)) != NULL) {
-		kfree_skb(skb);
-		vi->num--;
-	}
-	vi->svq->vq_ops->shutdown(vi->svq);
-	while ((skb = __skb_dequeue(&vi->send)) != NULL)
-		kfree_skb(skb);
-
-	BUG_ON(vi->num != 0);
 	return 0;
 }
 
@@ -379,10 +360,22 @@ static int virtnet_probe(struct virtio_device *vdev)
 		pr_debug("virtio_net: registering device failed\n");
 		goto free_send;
 	}
+
+	/* Last of all, set up some receive buffers. */
+	try_fill_recv(vi);
+
+	/* If we didn't even get one input buffer, we're useless. */
+	if (vi->num == 0) {
+		err = -ENOMEM;
+		goto unregister;
+	}
+
 	pr_debug("virtnet: registered device %s\n", dev->name);
 	vdev->priv = vi;
 	return 0;
 
+unregister:
+	unregister_netdev(dev);
 free_send:
 	vdev->config->del_vq(vi->svq);
 free_recv:
@@ -395,6 +388,19 @@ static int virtnet_probe(struct virtio_device *vdev)
 static void virtnet_remove(struct virtio_device *vdev)
 {
 	struct virtnet_info *vi = vdev->priv;
+	struct sk_buff *skb;
+
+	/* Free our skbs in send and recv queues, if any. */
+	vi->rvq->vq_ops->shutdown(vi->rvq);
+	while ((skb = __skb_dequeue(&vi->recv)) != NULL) {
+		kfree_skb(skb);
+		vi->num--;
+	}
+	vi->svq->vq_ops->shutdown(vi->svq);
+	while ((skb = __skb_dequeue(&vi->send)) != NULL)
+		kfree_skb(skb);
+
+	BUG_ON(vi->num != 0);
 
 	vdev->config->del_vq(vi->svq);
 	vdev->config->del_vq(vi->rvq);