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Subject: Re: [PATCH RFC net-next 2/2] drivers: net: virtio_net: Add tx_timeout
 function
To:     jcfaracco@gmail.com, netdev@vger.kernel.org
Cc:     mst@redhat.com, davem@davemloft.net,
        virtualization@lists.linux-foundation.org,
        linux-kernel@vger.kernel.org, dnmendes76@gmail.com
References: <20191006184515.23048-1-jcfaracco@gmail.com>
 <20191006184515.23048-3-jcfaracco@gmail.com>
From:   Jason Wang <jasowang@redhat.com>
Message-ID: <6c7a48ee-b900-c77d-8d12-35fd242f2e6f@redhat.com>
Date:   Sat, 12 Oct 2019 21:01:28 +0800
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On 2019/10/7 上午2:45, jcfaracco@gmail.com wrote:
> From: Julio Faracco <jcfaracco@gmail.com>
>
> To enable dev_watchdog, virtio_net should have a tx_timeout defined
> (.ndo_tx_timeout). This is only a skeleton to throw a warn message. It
> notifies the event in some specific queue of device. This function
> still counts tx_timeout statistic and consider this event as an error
> (one error per queue), reporting it.
>
> Signed-off-by: Julio Faracco <jcfaracco@gmail.com>
> Signed-off-by: Daiane Mendes <dnmendes76@gmail.com>
> Cc: Jason Wang <jasowang@redhat.com>
> ---
>   drivers/net/virtio_net.c | 27 +++++++++++++++++++++++++++
>   1 file changed, 27 insertions(+)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 27f9b212c9f5..4b703b4b9441 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -2585,6 +2585,29 @@ static int virtnet_set_features(struct net_device *dev,
>   	return 0;
>   }
>   
> +static void virtnet_tx_timeout(struct net_device *dev)
> +{
> +	struct virtnet_info *vi = netdev_priv(dev);
> +	u32 i;
> +
> +	/* find the stopped queue the same way dev_watchdog() does */
> +	for (i = 0; i < vi->curr_queue_pairs; i++) {
> +		struct send_queue *sq = &vi->sq[i];
> +
> +		if (!netif_xmit_stopped(netdev_get_tx_queue(dev, i)))
> +			continue;
> +
> +		u64_stats_update_begin(&sq->stats.syncp);
> +		sq->stats.tx_timeouts++;
> +		u64_stats_update_end(&sq->stats.syncp);
> +
> +		netdev_warn(dev, "TX timeout on send queue: %d, sq: %s, vq: %d, name: %s\n",
> +			    i, sq->name, sq->vq->index, sq->vq->name);


If this is just a warn for a specific queue, maybe it's better to do it 
in the dev_watchdog()?

Or we may want more information like avail,used idx etc.

And usually there will be a reset, any reason for not doing this?

Thanks


> +
> +		dev->stats.tx_errors++;
> +	}
> +}
> +
>   static const struct net_device_ops virtnet_netdev = {
>   	.ndo_open            = virtnet_open,
>   	.ndo_stop   	     = virtnet_close,
> @@ -2600,6 +2623,7 @@ static const struct net_device_ops virtnet_netdev = {
>   	.ndo_features_check	= passthru_features_check,
>   	.ndo_get_phys_port_name	= virtnet_get_phys_port_name,
>   	.ndo_set_features	= virtnet_set_features,
> +	.ndo_tx_timeout		= virtnet_tx_timeout,
>   };
>   
>   static void virtnet_config_changed_work(struct work_struct *work)
> @@ -3018,6 +3042,9 @@ static int virtnet_probe(struct virtio_device *vdev)
>   	dev->netdev_ops = &virtnet_netdev;
>   	dev->features = NETIF_F_HIGHDMA;
>   
> +	/* Set up dev_watchdog cycle. */
> +	dev->watchdog_timeo = 5 * HZ;
> +
>   	dev->ethtool_ops = &virtnet_ethtool_ops;
>   	SET_NETDEV_DEV(dev, &vdev->dev);
>