netdev - Re: [PATCH net] r8169: fix multicast tx issue with macvlan interface

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Date:   Thu, 30 Apr 2020 18:50:40 +0200
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Florent Fourcot <florent.fourcot@...irst.fr>,
        Eric Dumazet <edumazet@...gle.com>
Cc:     Charles DAYMAND <charles.daymand@...irst.fr>,
        netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH net] r8169: fix multicast tx issue with macvlan interface

On 27.04.2020 23:12, Florent Fourcot wrote:
> Hello Eric, Hello Heiner,
> 
> Just for a small follow-up on your questions and current status on our side for this strange topic:
> 
>  * As explained by Charles, the setup includes a mix of macvlan + vlan. So 802.1q frames are not a typo in the topic (in our real case, the second macvlan interface is sent to a network namespace, but it does not matter for the current issue).
> 
>  * We tested the same setup with other networking driver (bnx2, tg3) with tx-checksum enabled (exactly same configuration than the failing one on r8169 for checksum offloading), and it's perfectly working.
> 
>  * Packets are seen as valid by tcpdump on the sender (buggy) host.
> 
>  * Multicast *and* unicast packets are buggy. We detected it first on multicast (since the relevant hardware was sending RIP packets), but all tcp/udp packets are corrupted. ICMP packets are valid.
> 
>  * We expected as well a "simple" checksum failure, but it does not look so simple. Something, on our opinion probably the driver or hardware, is corrupting the packet.
> 
>  * Experimental patches from Heiner are not solving issue.
> 
>  * We have the same behavior on at least RTL8168d/8111d, RTL8169sc/8110sc and RTL8168h/8111h variants.
> 
> 
> As proposed by Heiner, we will try to debug step by step packet path inside the kernel to find where it's become corrupted. But it looks time consuming for people like us, not really experts in driver development. If you have any tips or ideas concerning this topic, it could help us a lot.
> 
> Best regards,
> 

Previously in this thread you sent an example of a corrupted packet, a LLC packet.
For my understanding, is LLC configured in your config? See net/llc/Kconfig.
If yes, then does the issue also occur with this option disabled?

Heiner