# Re: \[PATCH net-next\] virtio\_net: set link state down when virtqueue is broken

- From: Jason Wang \<hidden\>
- Date: 2021-05-27 04:22:34 
- List: netdev
- Page: https://ratatoskr.run/netdev/2021/05/11203907
- Thread: https://ratatoskr.run/netdev/2021/05/11203818/t.md

```text

在 2021/5/26 下午7:39, wangyunjian 写道:
> From: Yunjian Wang <redacted>
>
> The NIC can't receive/send packets if a rx/tx virtqueue is broken.
> However, the link state of the NIC is still normal. As a result,
> the user cannot detect the NIC exception.


Doesn't we have:

       /* This should not happen! */
        if (unlikely(err)) {
                dev->stats.tx_fifo_errors++;
                if (net_ratelimit())
                        dev_warn(&dev->dev,
                                 "Unexpected TXQ (%d) queue failure: %d\n",
                                 qnum, err);
                dev->stats.tx_dropped++;
                dev_kfree_skb_any(skb);
                return NETDEV_TX_OK;
        }

Which should be sufficient?


>
> The driver can set the link state down when the virtqueue is broken.
> If the state is down, the user can switch over to another NIC.


Note that, we probably need the watchdog for virtio-net in order to be a complete solution.

Thanks


>
> Signed-off-by: Yunjian Wang <redacted>
> ---
>   drivers/net/virtio_net.c | 36 +++++++++++++++++++++++++++++++++++-
>   1 file changed, 35 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 073fec4c0df1..05a3cd1c589b 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -237,6 +237,10 @@ struct virtnet_info {
>   
>   	/* failover when STANDBY feature enabled */
>   	struct failover *failover;
> +
> +	/* Work struct for checking vq status, stop NIC if vq is broken. */
> +	struct delayed_work vq_check_work;
> +	bool broken;
>   };
>   
>   struct padded_vnet_hdr {
> @@ -1407,6 +1411,27 @@ static void refill_work(struct work_struct *work)
>   	}
>   }
>   
> +static void virnet_vq_check_work(struct work_struct *work)
> +{
> +	struct virtnet_info *vi =
> +		container_of(work, struct virtnet_info, vq_check_work.work);
> +	struct net_device *netdev = vi->dev;
> +	int i;
> +
> +	if (vi->broken)
> +		return;
> +
> +	/* If virtqueue is broken, set link down and stop all queues */
> +	for (i = 0; i < vi->max_queue_pairs; i++) {
> +		if (virtqueue_is_broken(vi->rq[i].vq) || virtqueue_is_broken(vi->sq[i].vq)) {
> +			netif_carrier_off(netdev);
> +			netif_tx_stop_all_queues(netdev);
> +			vi->broken = true;
> +			break;
> +		}
> +	}
> +}
> +
>   static int virtnet_receive(struct receive_queue *rq, int budget,
>   			   unsigned int *xdp_xmit)
>   {
> @@ -1432,6 +1457,9 @@ static int virtnet_receive(struct receive_queue *rq, int budget,
>   		}
>   	}
>   
> +	if (unlikely(!virtqueue_is_broken(rq->vq)))
> +		schedule_delayed_work(&vi->vq_check_work, HZ);
> +
>   	if (rq->vq->num_free > min((unsigned int)budget, virtqueue_get_vring_size(rq->vq)) / 2) {
>   		if (!try_fill_recv(vi, rq, GFP_ATOMIC))
>   			schedule_delayed_work(&vi->refill, 0);
> @@ -1681,6 +1709,7 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev)
>   				 qnum, err);
>   		dev->stats.tx_dropped++;
>   		dev_kfree_skb_any(skb);
> +		schedule_delayed_work(&vi->vq_check_work, HZ);
>   		return NETDEV_TX_OK;
>   	}
>   
> @@ -1905,6 +1934,7 @@ static int virtnet_close(struct net_device *dev)
>   
>   	/* Make sure refill_work doesn't re-enable napi! */
>   	cancel_delayed_work_sync(&vi->refill);
> +	cancel_delayed_work_sync(&vi->vq_check_work);
>   
>   	for (i = 0; i < vi->max_queue_pairs; i++) {
>   		xdp_rxq_info_unreg(&vi->rq[i].xdp_rxq);
> @@ -2381,6 +2411,7 @@ static void virtnet_freeze_down(struct virtio_device *vdev)
>   	netif_device_detach(vi->dev);
>   	netif_tx_unlock_bh(vi->dev);
>   	cancel_delayed_work_sync(&vi->refill);
> +	cancel_delayed_work_sync(&vi->vq_check_work);
>   
>   	if (netif_running(vi->dev)) {
>   		for (i = 0; i < vi->max_queue_pairs; i++) {
> @@ -2662,7 +2693,7 @@ static void virtnet_config_changed_work(struct work_struct *work)
>   
>   	vi->status = v;
>   
> -	if (vi->status & VIRTIO_NET_S_LINK_UP) {
> +	if ((vi->status & VIRTIO_NET_S_LINK_UP) && !vi->broken) {
>   		virtnet_update_settings(vi);
>   		netif_carrier_on(vi->dev);
>   		netif_tx_wake_all_queues(vi->dev);
> @@ -2889,6 +2920,8 @@ static int virtnet_alloc_queues(struct virtnet_info *vi)
>   		goto err_rq;
>   
>   	INIT_DELAYED_WORK(&vi->refill, refill_work);
> +	INIT_DELAYED_WORK(&vi->vq_check_work, virnet_vq_check_work);
> +
>   	for (i = 0; i < vi->max_queue_pairs; i++) {
>   		vi->rq[i].pages = NULL;
>   		netif_napi_add(vi->dev, &vi->rq[i].napi, virtnet_poll,
> @@ -3240,6 +3273,7 @@ static int virtnet_probe(struct virtio_device *vdev)
>   	net_failover_destroy(vi->failover);
>   free_vqs:
>   	cancel_delayed_work_sync(&vi->refill);
> +	cancel_delayed_work_sync(&vi->vq_check_work);
>   	free_receive_page_frags(vi);
>   	virtnet_del_vqs(vi);
>   free:

```