Re: [PATCH net-next v4 4/4] net: gro: move L3 flush checks to tcp_gro_receive

[Eric Dumazet]

On Tue, Mar 26, 2024 at 3:43 PM Richard Gobert <richardbgobert@xxxxxxxxx> wrote:
>
> Eric Dumazet wrote:
> > On Mon, Mar 25, 2024 at 7:27 PM Richard Gobert <richardbgobert@xxxxxxxxx> wrote:
> >>
> >> {inet,ipv6}_gro_receive functions perform flush checks (ttl, flags,
> >> iph->id, ...) against all packets in a loop. These flush checks are used
> >> currently only in tcp flows in GRO.
> >
> > I think this is a bug.
> >
> > GRO should not aggregate packets if their ttl/tos fields do not match.
>
> AFAIU, the only UDP flow where ttl/flush_id need to be checked is when
> udp_gro_receive_segment calls skb_gro_receive - could you confirm / point
> out if there are any other flows to which these flush checks may be
> relevant?
>
> As I've discussed with Willem in v3 I prefer to fix this bug in a separate
> series.

I do not understand this patch 4/4 then.

Why bother moving stuff in net/ipv4/tcp_offload.c if we plan to move
it back to where it belongs ?