Re: [PATCH bpf-next] tools/testing/selftests/bpf/test_tc_tunnel.sh: Fix wait for server bind

[Marco Leogrande]

On Mon, Dec 2, 2024 at 4:15 PM Stanislav Fomichev <stfomichev@xxxxxxxxx> wrote:
> Do you see this failing in your CI or in the BPF CI?

I see this failing in our internal CI, in around 1% to 2% of the CI runs.

> It seems ok
> to add wait_for_port here, but the likelihood of the issue seems
> minuscule. There is a bunch of ip/tc/etc calls between this
> server_listen and the next client_connect (and I'd be surprised to hear
> that netcat is still not listening by the time we reach next
> client_connect).

I'm surprised as well, and I've not found a good correlation with the
root cause of the delayed server start, besides generic "slowness".

You also make a good point - by calling wait_for_port this early we
"waste" the opportunity to run the other ip commands in parallel in
the meantime.
I had considered moving this wait down, just before the next
client_connect, but I concluded it might be less readable since it
would be so distant from the server_listen it pairs with. But I can
make that change if it seems better.