On Fri, May 5, 2017 at 1:17 PM, Vladislav Yasevich <vyasev...@gmail.com> wrote:
> Vlan devices, like all other software devices, enable
> NETIF_F_HW_CSUM feature. However, unlike all the othe other
> software devices, vlans will switch to using IP|IPV6_CSUM
> features, if the underlying devices uses them. In these situations,
> checksum offload features on the vlan device can't be controlled
> via ethtool.
>
> This patch makes vlans keep HW_CSUM feature if the underlying
> device supports checksum offloading. This makes vlan devices
> behave like other software devices, and restores control to the
> user.
>
> A side-effect is that some offload settings (typically UFO)
> may be enabled on the vlan device while being disabled on the HW.
> However, the GSO code will correctly process the packets. This
> actually results in slightly better raw throughput.
>
> Signed-off-by: Vladislav Yasevich <vyase...@redhat.com>
Acked-by: Alexander Duyck <alexander.h.du...@intel.com>
> ---
> V2: posted the right patch.
>
> net/8021q/vlan_dev.c | 13 ++++++++++---
> 1 file changed, 10 insertions(+), 3 deletions(-)
>
> diff --git a/net/8021q/vlan_dev.c b/net/8021q/vlan_dev.c
> index 9ee5787..ff12cf3 100644
> --- a/net/8021q/vlan_dev.c
> +++ b/net/8021q/vlan_dev.c
> @@ -626,11 +626,18 @@ static netdev_features_t vlan_dev_fix_features(struct
> net_device *dev,
> {
> struct net_device *real_dev = vlan_dev_priv(dev)->real_dev;
> netdev_features_t old_features = features;
> + netdev_features_t lower_features;
>
> - features = netdev_intersect_features(features,
> real_dev->vlan_features);
> - features |= NETIF_F_RXCSUM;
> - features = netdev_intersect_features(features, real_dev->features);
> + lower_features = netdev_intersect_features((real_dev->vlan_features |
> + NETIF_F_RXCSUM),
> + real_dev->features);
>
> + /* Add HW_CSUM setting to preserve user ability to control
> + * checksum offload on the vlan device.
> + */
> + if (lower_features & (NETIF_F_IP_CSUM|NETIF_F_IPV6_CSUM))
> + lower_features |= NETIF_F_HW_CSUM;
> + features = netdev_intersect_features(features, lower_features);
> features |= old_features & (NETIF_F_SOFT_FEATURES |
> NETIF_F_GSO_SOFTWARE);
> features |= NETIF_F_LLTX;
>
> --
> 2.7.4
>
