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

[jcfaracco@gmail.com]

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);
+
+		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);
 
-- 
2.21.0