On Thu, 2016-03-10 at 09:28 -0500, Aaron Conole wrote:
> This patch checks the feature bit for the VIRTIO_NET_F_MTU feature. If it
> exists, read the advised MTU and use it.
>
> No proper error handling is provided for the case where a user changes the
> negotiated MTU. A future commit will add proper error handling. Instead, a
> warning is emitted if the guest changes the device MTU after previously being
> given advice.
>
> Signed-off-by: Aaron Conole <aconole@xxxxxxxxxx>
> ---
> drivers/net/virtio_net.c | 15 ++++++++++++++-
> 1 file changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 767ab11..7175563 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -146,6 +146,7 @@ struct virtnet_info {
> virtio_net_ctrl_ack ctrl_status;
> u8 ctrl_promisc;
> u8 ctrl_allmulti;
> + bool negotiated_mtu;
> };
>
> struct padded_vnet_hdr {
> @@ -1390,8 +1391,12 @@ static const struct ethtool_ops virtnet_ethtool_ops = {
>
> static int virtnet_change_mtu(struct net_device *dev, int new_mtu)
> {
> + struct virtnet_info *vi = netdev_priv(dev);
> if (new_mtu < MIN_MTU || new_mtu > MAX_MTU)
> return -EINVAL;
> + if (vi->negotiated_mtu == true) {
why don't:
if ((vi->negotiated_mtu == true) && (dev->mtu != new_mtu))
?
> + pr_warn("changing mtu from negotiated mtu.");
> + }
> dev->mtu = new_mtu;
> return 0;
> }
> @@ -1836,6 +1841,13 @@ static int virtnet_probe(struct virtio_device *vdev)
> if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ))
> vi->has_cvq = true;
>
> + if (virtio_has_feature(vdev, VIRTIO_NET_F_MTU)) {
> + vi->negotiated_mtu = true;
> + dev->mtu = virtio_cread16(vdev,
> + offsetof(struct virtio_net_config,
> + mtu));
> + }
> +
> if (vi->any_header_sg)
> dev->needed_headroom = vi->hdr_len;
>
> @@ -2017,8 +2029,9 @@ static unsigned int features[] = {
> VIRTIO_NET_F_MRG_RXBUF, VIRTIO_NET_F_STATUS, VIRTIO_NET_F_CTRL_VQ,
> VIRTIO_NET_F_CTRL_RX, VIRTIO_NET_F_CTRL_VLAN,
> VIRTIO_NET_F_GUEST_ANNOUNCE, VIRTIO_NET_F_MQ,
> - VIRTIO_NET_F_CTRL_MAC_ADDR,
> + VIRTIO_NET_F_CTRL_MAC_ADDR,
Here a trailing white space slipped-in.
Otherwise LGTM.
Paolo
> VIRTIO_F_ANY_LAYOUT,
> + VIRTIO_NET_F_MTU,
> };
>
> static struct virtio_driver virtio_net_driver = {
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