On Fri, 11 Sep 2026 15:41:33 -0300 Ricardo B. Marlière (SUSE) wrote: > icmp.sh backgrounds ping and then starts tcpdump, with no synchronization > between the two. If tcpdump is not capturing yet by the time the ICMP > unreachable replies come back, the test fails even though the kernel > behaved correctly: > > FAIL - got ICMP response from , should be 192.0.0.8 > > The empty address is misleading: it means the capture matched nothing > before its 10s timeout, not that the reply had a wrong source address. > NS1's Icmp InDestUnreachs counter still increments across such a failure, > so the replies were generated and did reach NS1. Ping sends several probes > over its 3s deadline, so losing every one of them takes a multi-second > stall in tcpdump startup, which does happen on loaded CI hosts [1]. > > Fix it by starting tcpdump first and waiting for its "listening" banner > via slowwait() before sending traffic. Run ping synchronously, then kill > and reap tcpdump if it did not already exit on -c 1.
It used to pass in NIPA CI and now it fails: https://netdev-ctrl.bots.linux.dev/logs/vmksft/net-dbg/results/819341/86-icmp-sh/stdout > Fixes: 7e9838b7915e ("selftests/net: Add icmp.sh for testing ICMP dummy > address responses") Please don't add Fixes tags to selftest improvements. > Link: > https://openqa.opensuse.org/tests/5907626/logfile?filename=icmp_sh.tap.txt#line-2 > [1] > Signed-off-by: Ricardo B. Marlière (SUSE) <[email protected]>
