Re: [PATCH net-next v3 4/4] net: gro: move L3 flush checks to tcp_gro_receive

[Eric Dumazet]

On Sat, Mar 9, 2024 at 4:35 PM Richard Gobert <richardbgobert@gmailcom> wrote:
>
> {inet,ipv6}_gro_receive functions perform flush checks (ttl, flags,
> iph->id, ...) against all packets in a loop. These flush checks are
> relevant only to tcp flows, and as such they're used to determine whether
> the packets can be merged later in tcp_gro_receive.
>
> These checks are not relevant to UDP packets.

I do not think this claim is true.

Incoming packets  ->  GRO -> GSO -> forwarded packets

The {GRO,GSO} step must be transparent, GRO is not LRO.