Re: [PATCH RFC net-next 2/2] drivers: net: virtio_net: Add tx_timeout function

[Jason Wang]

On 2019/10/7 äå3:51, Michael S. Tsirkin wrote:
> On Sun, Oct 06, 2019 at 03:45:15PM -0300, jcfaracco@xxxxxxxxx wrote:
> > From: Julio Faracco <jcfaracco@xxxxxxxxx>
> >
> > 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@xxxxxxxxx>
> > Signed-off-by: Daiane Mendes <dnmendes76@xxxxxxxxx>
> > Cc: Jason Wang <jasowang@xxxxxxxxxx>
> > ---
> >   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 */
> not really - the watchdog actually looks at trans_start.
>
> > +	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);
> this seems to assume any running queue is timed out.
> doesn't look right.
>
> also - there's already a warning in this case in the core. do we need another one?
>
> > +		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;
> > +
> Seems to be still broken with napi_tx = false.


With napi_tx = false, we still have tx interrupt after we stop the queue 
which looks fine I believe?

Thanks


> >   	dev->ethtool_ops = &virtnet_ethtool_ops;
> >   	SET_NETDEV_DEV(dev, &vdev->dev);
> >   
> > --
> > 2.21.0