Re: [PATCH] selftests: net: fou_mcast_encap: conditionally load fou module and skip IPv4 case

[Jakub Kicinski <kuba@kernel.org>]

On Thu, 17 Sep 2026 11:33:09 +0800 Qingshuang Fu wrote:
> >> +if modprobe -q fou; then
> >> +	setup_ipv4
> >> +	run_ping_test -4 eoudp4 "$TUN4_R" "FOU/GRETAP IPv4 multicast encap resubmit"
> >> +else
> >> +	log_test_skip "FOU/GRETAP IPv4 multicast encap resubmit"
> >> +fi  
> > 
> > Two very important questions you must answer before posting v2 or any
> > other similar fix:
> > 
> > Have you actually run into this or it's a result of an LLM scan?
> > 
> > How many of such fixes would we need to make all the net/ tests
> > clean from similar issues?  
> 
> I noticed it reading the script, then reproduced it on 6.8.0-138-generic.
> This Ubuntu kernel ships with CONFIG_NET_FOU=m by default. Without the fou
> module loaded, tunnel creation fails with "RTNETLINK answers: Invalid 
> argument"
> and the test reports a false failure at 0/100 packets. After applying 
> the patch
> the subtest skips cleanly.
> 
> For FOU this was the only gap. The two other net/ tests that use it
> (pmtu.sh, rtnetlink.sh) already load the module.

I did not ask about FOU

> v2 sent: drop Fixes tag and the in‑script comment as requested. Thanks 
> for the review.

I guess I wasn't clear enough. When I say "before posting v2" 
I was hoping you'd give me a chance to respond too :/

Whatever.