netdev - Re: [PATCH net-next v3] net: pppoe: implement GRO/GSO support

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Message-ID: <38c4355b-4570-401e-b520-7ec698b62dd8@redhat.com>
Date: Mon, 18 Aug 2025 15:32:15 +0200
From: Paolo Abeni <pabeni@...hat.com>
To: Richard Gobert <richardbgobert@...il.com>, Felix Fietkau <nbd@....name>,
 netdev@...r.kernel.org, Michal Ostrowski <mostrows@...thlink.net>,
 Andrew Lunn <andrew+netdev@...n.ch>, "David S. Miller"
 <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>, David Ahern <dsahern@...nel.org>,
 Simon Horman <horms@...nel.org>
Cc: linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next v3] net: pppoe: implement GRO/GSO support

On 8/18/25 1:22 PM, Richard Gobert wrote:
> Felix Fietkau wrote:
>> On 14.08.25 16:30, Richard Gobert wrote:
>>> I don't think this will be called for PPPoE over GRE packets,
>>> since gre_gso_segment skips everything up to the network header.
>>
>> What's a good solution to this issue? Use the outer network header instead of the inner one when the protocol is PPPoE?
>>
>> - Felix
> 
> I don't really have a good solution for this. You could explicitly check
> if the protocol is PPPoE in gre_gso_segment, but that wouldn't be very
> elegant or future-proof.
>  
> I think setting skb->inner_network_header in pppoe_gro_complete
> (while not resetting it in inet_gro_complete) wouldn't work since other
> functions assume that skb->inner_network_header is an IP header.

Is PPPoE over GRE really a thing? IOW do we need to care at the GRO
level? FTR, my biased answers are "no" and "no" ;)

/P