netdev - Re: [PATCH v3 net-next 1/2] udp_tunnel: create a fastpath GRO lookup.

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Message-ID: <7a4c78fa-1eeb-4fa9-9360-269821ff5fdb@redhat.com>
Date: Tue, 11 Mar 2025 17:38:27 +0100
From: Paolo Abeni <pabeni@...hat.com>
To: Willem de Bruijn <willemdebruijn.kernel@...il.com>, netdev@...r.kernel.org
Cc: "David S. Miller" <davem@...emloft.net>,
 Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
 Simon Horman <horms@...nel.org>, David Ahern <dsahern@...nel.org>,
 kuniyu@...zon.com
Subject: Re: [PATCH v3 net-next 1/2] udp_tunnel: create a fastpath GRO lookup.

On 3/11/25 3:32 AM, Willem de Bruijn wrote:
> Paolo Abeni wrote:
>> Most UDP tunnels bind a socket to a local port, with ANY address, no
>> peer and no interface index specified.
>> Additionally it's quite common to have a single tunnel device per
>> namespace.
>>
>> Track in each namespace the UDP tunnel socket respecting the above.
>> When only a single one is present, store a reference in the netns.
>>
>> When such reference is not NULL, UDP tunnel GRO lookup just need to
>> match the incoming packet destination port vs the socket local port.
>>
>> The tunnel socket never sets the reuse[port] flag[s]. When bound to no
>> address and interface, no other socket can exist in the same netns
>> matching the specified local port.
> 
> What about packets with a non-local daddr (e.g., forwarding)?

I'm unsure if I understand the question. Such incoming packets at the
GRO stage will match the given tunnel socket, either by full socket
lookup or by dport only selection.

If the GSO packet will be forwarded, it will segmented an xmit time.

Possibly you mean something entirely different?!?

Thanks!

Paolo