On Thu, Oct 20, 2016 at 11:23:54PM +0300, Michael S. Tsirkin wrote:
> On Thu, Oct 20, 2016 at 01:55:21PM -0400, Jarod Wilson wrote:
...
> > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > index fad84f3..720809f 100644
> > --- a/drivers/net/virtio_net.c
> > +++ b/drivers/net/virtio_net.c
> > @@ -1419,17 +1419,6 @@ static const struct ethtool_ops virtnet_ethtool_ops
> > = {
> > .set_settings = virtnet_set_settings,
> > };
> >
> > -#define MIN_MTU 68
> > -#define MAX_MTU 65535
> > -
> > -static int virtnet_change_mtu(struct net_device *dev, int new_mtu)
> > -{
> > - if (new_mtu < MIN_MTU || new_mtu > MAX_MTU)
> > - return -EINVAL;
> > - dev->mtu = new_mtu;
> > - return 0;
> > -}
> > -
> > static const struct net_device_ops virtnet_netdev = {
> > .ndo_open = virtnet_open,
> > .ndo_stop = virtnet_close,
> > @@ -1437,7 +1426,6 @@ static const struct net_device_ops virtnet_netdev = {
> > .ndo_validate_addr = eth_validate_addr,
> > .ndo_set_mac_address = virtnet_set_mac_address,
> > .ndo_set_rx_mode = virtnet_set_rx_mode,
> > - .ndo_change_mtu = virtnet_change_mtu,
> > .ndo_get_stats64 = virtnet_stats,
> > .ndo_vlan_rx_add_vid = virtnet_vlan_rx_add_vid,
> > .ndo_vlan_rx_kill_vid = virtnet_vlan_rx_kill_vid,
> > @@ -1748,6 +1736,9 @@ static bool virtnet_validate_features(struct
> > virtio_device *vdev)
> > return true;
> > }
> >
> > +#define MIN_MTU ETH_MIN_MTU
> > +#define MAX_MTU ETH_MAX_MTU
> > +
>
> Can we drop these btw?
Bah. Yeah. Should have just used them directly. I didn't add ETH_MAX_MTU
until after doing the virtio_net changes, so I missed that.
> > static int virtnet_probe(struct virtio_device *vdev)
> > {
> > int i, err;
> > @@ -1821,6 +1812,10 @@ static int virtnet_probe(struct virtio_device *vdev)
> >
> > dev->vlan_features = dev->features;
> >
> > + /* MTU range: 68 - 65535 */
> > + dev->min_mtu = MIN_MTU;
> > + dev->max_mtu = MAX_MTU;
> > +
> > /* Configuration may specify what MAC to use. Otherwise random. */
> > if (virtio_has_feature(vdev, VIRTIO_NET_F_MAC))
> > virtio_cread_bytes(vdev,
> > @@ -1875,8 +1870,10 @@ static int virtnet_probe(struct virtio_device *vdev)
> > mtu = virtio_cread16(vdev,
> > offsetof(struct virtio_net_config,
> > mtu));
> > - if (virtnet_change_mtu(dev, mtu))
> > + if (mtu < dev->min_mtu || mtu > dev->max_mtu)
>
> In fact the > max_mtu branch does not make sense since a 16 bit
> value can't exceed MAX_MTU.
Hm. mtu is declared as an int, not sure if there's any sort of type
promotion to be worried about (not an area I know much/anything about).
Certainly something that could be looked into as a minor optimization,
though it's only in a probe path and shouldn't hurt anything, so ... meh?
--
Jarod Wilson
ja...@redhat.com
