Re: [Devel] [PATCH hci-8.1 1/2] selftests: net: veth: check UDP GRO forwarding on forwarded traffic

[Konstantin Khorenko <khorenko@virtuozzo.com>]

On 10/26/26 13:06, Eva Kurchatova wrote:
> pass on a host where nothing does. Since commit 36707061d6ba ("udp:
> allow forwarding of plain (non-fraglisted) UDP GRO packets") the
> feature aggregates only datagrams GRO finds no socket for, and GRO
> looks the socket up only once a tunnel socket exists on the host; the

The lookup behind the static key comes from f2e9de210d50 ("udp: gro
behind static key"), not from 36707061d6ba. And not only tunnels turn
it on: setsockopt(UDP_GRO) does too, in any netns.

> while nothing looks it up.
> This tree made them pass by changing the kernel instead, in commit
> 8ce3afeec4ca ("udp: let rx-udp-gro-forwarding aggregate under

Blank line missing before this paragraph. checkpatch also wants
"commit 8ce3afeec4ca" on one line.

> +# The receiver of the GRO checks, behind the destination
> +readonly RCV=3
[...]
> +# Network between the destination and the receiver
> +readonly RCV_NET_V4=192.168.2.

Both comments restate the names, dropped.

> +     # Forwarded, the datagrams find no local socket, whatever tunnel the host has

"whatever the host runs": not only tunnels, see above.

> +     ip link add name fwd$DST type veth peer name fwd$RCV
> +     ip link set dev fwd$DST netns $NS_DST up
> +     ip link set dev fwd$RCV netns $NS_RCV up

Better create the pair right in the namespaces, so no fwd1/fwd3 ever
appears in init_net:

        ip -n $NS_DST link add name fwd$DST type veth peer name fwd$RCV netns $NS_RCV
        ip -n $NS_DST link set dev fwd$DST up
        ip -n $NS_RCV link set dev fwd$RCV up

All fixed in v2.

--
Best regards,

Konstantin Khorenko,
Virtuozzo Linux Kernel Team


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