Re: [PATCH net-next 2/8] udp: skip fwd/list GRO for tunnel packets
flat view
From: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Date: 2021-03-22 13:26:12
On Sun, Mar 21, 2021 at 1:01 PM Paolo Abeni [off-list ref] wrote:
If UDP GRO forwarding (or list) is enabled,
Please explicitly mention the gso type SKB_GSO_FRAGLIST. I, at least,
didn't immediately grasp that gro forwarding is an alias for that.
and there are udp tunnel available in the system, we could end-up doing L4 aggregation for packets targeting the UDP tunnel.
Is this specific to UDP tunnels, or can this also occur with others,
such as GRE? (not implying that this patchset needs to address those
at the same time)
That could inner protocol corruption, as no overaly network parameters is taken in account at aggregation time.
nit: overaly .. is taken -> overlay .. are taken
You mean the packets on the frag list may have mtu exceeding the mtu
of the tunnel? Please make the constraint more explicit.
Just skip the fwd GRO if this packet could land in an UDP tunnel.
Could you make more clear that this does not skip UDP GRO, only
switches from fraglist-based to pure SKB_GSO_UDP_L4.
The current check is broader than what is strictly
needed, as the UDP tunnel could be e.g. on top of a different
device, but is simple and the performance downside looks not
relevant.
Fixes: 9fd1ff5d2ac7 ("udp: Support UDP fraglist GRO/GSO.")
Fixes: 36707061d6ba ("udp: allow forwarding of plain (non-fraglisted) UDP GRO packets")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>