Re: [PATCH bpf-next v11 2/5] selftests/bpf: add bpf_icmp_send kfunc cgroup_skb tests

[Stanislav Fomichev <sdf.kernel@gmail.com>]

On 07/09, Mahe Tardy wrote:
> This test opens a server and client, enters a new cgroup, attach a
> cgroup_skb program on egress and calls the bpf_icmp_send function from
> the client egress so that an ICMP unreach control message is sent back
> to the client. It then fetches the message from the error queue to
> confirm the correct ICMP unreach code has been sent.
> 
> Note that, for the client, we have to connect in non-blocking mode to
> let the test execute faster. Otherwise, we need to wait for the TCP
> three-way handshake to timeout in the kernel before reading the errno.
> 
> Also note that we don't set IP_RECVERR on the socket in
> connect_to_fd_nonblock since the error will be transferred anyway in our
> test because the connection is rejected at the beginning of the TCP
> handshake. See in net/ipv4/tcp_ipv4.c:tcp_v4_err for more details.
> 
> Reviewed-by: Jordan Rife <jordan@jrife.io>
> Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
> Signed-off-by: Mahe Tardy <mahe.tardy@gmail.com>

Acked-by: Stanislav Fomichev <sdf@fomichev.me>