On 2025-08-22 18:32, Jakub Kicinski wrote:
Thanks for bisecting and fixing!
The broadcast_pmtu.sh selftest provided with the original patch still passes with this patch applied.
Hm, yes, AFACT we're losing PMTU discovery but perhaps original commit wasn't concerned with that. Hopefully Oscar can comment.
Indeed. This takes it back to the previous behaviour.
On Fri, 22 Aug 2025 16:50:51 +0000 Brett A C Sheffield wrote:
if (type == RTN_BROADCAST) {/* ensure MTU value for broadcast routes is retained */ip_dst_init_metrics(&rth->dst, res->fi->fib_metrics);You need to check if res->fi is actually set before using it
Ah, yes. Fixed.
Could you add a selftest / test case for the scenario we broke? selftests can be in C / bash / Python. If bash hopefully socat can be used to repro, cause it looks like wakeonlan is not very widely packaged.
Self-test added using socat as requested. If you want this wrapped in namespaces etc. let me know. I started doing that, but decided a simpler test without requiring root was better and cleaner.
Thanks for the review Jakub. v2 patches sent.
Cheers,
Brett