On 2017/05/18 22:31, Vladislav Yasevich wrote:
> It appears that since commit 8cb65d000, Q-in-Q vlans have been
> broken. The series that commit is part of enabled TSO and checksum
> offloading on Q-in-Q vlans. However, most HW we support can't handle
> it. To work around the issue, the above commit added a function that
> turns off offloads on Q-in-Q devices, but it left the checksum offload.
> That will cause issues with most older devices that supprort very basic
> checksum offload capabilities as well as some newer devices (we've
> reproduced te problem with both be2net and bnx).
>
> To solve this for everyone, turn off checksum offloading feature
> by default when sending Q-in-Q traffic. Devices that are proven to
> work can provided a corrected ndo_features_check implemetation.
>
> Fixes: 8cb65d000 ("net: Move check for multiple vlans to drivers")
> CC: Toshiaki Makita <makita.toshi...@lab.ntt.co.jp>
> Signed-off-by: Vladislav Yasevich <vyase...@redhat.com>
> ---
> include/linux/if_vlan.h | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/include/linux/if_vlan.h b/include/linux/if_vlan.h
> index 8d5fcd6..ae537f0 100644
> --- a/include/linux/if_vlan.h
> +++ b/include/linux/if_vlan.h
> @@ -619,7 +619,6 @@ static inline netdev_features_t vlan_features_check(const
> struct sk_buff *skb,
> NETIF_F_SG |
> NETIF_F_HIGHDMA |
> NETIF_F_FRAGLIST |
> - NETIF_F_HW_CSUM |
> NETIF_F_HW_VLAN_CTAG_TX |
> NETIF_F_HW_VLAN_STAG_TX);
>
I guess HW_CSUM theoretically can handle Q-in-Q packets and the problem
is IP_CSUM and IPV6_CSUM.
So wouldn't it be better to leave HW_CSUM and drop IP_CSUM/IPV6_CSUM,
i.e. change intersection into bitwise AND?
The intersection was introduced in db115037bb57 ("net: fix checksum
features handling in netif_skb_features()"), but I guess for this
particular check the intersection was not needed.
--
Toshiaki Makita
