From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2718D3BE155 for ; Tue, 13 Oct 2026 08:41:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791880877; cv=none; b=fxKjTKBzyaV7LDlx93fTT0+/HTiHvWMs1E8+NBNaeZPqmtrsTpIVfI1HGkvs13lPzdRYxrI2PkYU3AiuPko+q7ziKa5B9T+oh9q998bsBIAuB1RNFDoCqLaZDvA2JZAZHXtK9ti2uKBMWOkKh5IpJeBDk/uSCxDa4dwBYQPf6iI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791880877; c=relaxed/simple; bh=HdV2lf1RSnZt4JJg5NsL/gxvZ4pNyy8xfT7j/N4E6uQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=nQHKai6pOovjNA2nJMfUMc0+qm65i2/a1Y9RHkIbxCl6ZR2MvoItkM5gB+/0HmrsZqRRJS//6BNvXOf3B1iGNLz7FYM6i1qZRMAbgBI8kH/vjMB73RAvo2oQZLPAInOAn8v/yklvgQ67BQGOGMjA7igKqgc/pdqt2Yihx8BXNCs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=DRIF1qvz; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="DRIF1qvz" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 368731F000FF; Tue, 13 Oct 2026 08:41:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791880874; bh=dauLebWjc4cMcvBim0l5yF31Aaj2J57N980UuMWrHyw=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=DRIF1qvzzLcHosNq2Sp5+M+MVe11MVnFPPNgcLKE2mc79D+GWs+9zOqU3QGCWO9Sz 7Gv9DOpD1QH7eY4VQPqHNDtVGDeEfBfDC6xEmNHGcS1j8YTm0ZvwwsWm4KvjtpHMzh 7hPg/py15cAAE9tojsEhSA3xPStZsRRdUmo4K28FtJ30TZC7dL3Nk6Pr7SxwGJ9fiq CON/Qew9vRN1ndrRqmupXCtxyT4id1fM4KJRg0FX8tHoqxsdehFdMnjxe1jV0hXc8x y7p01S8e0289UZfPTuav1wxk0Deo/5s9jxc3lYAzQuOsrFsUkKgxVxHZja+of9YoZk mkPfnU56Jb7Cg== Date: Tue, 13 Oct 2026 10:41:11 +0200 From: Antoine Tenart To: Prasenjit Mukherjee Cc: "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Shuah Khan , David Ahern , Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= , netdev@vger.kernel.org, Davide Caratti Subject: Re: [PATCH net] selftests: net: fix race condition in icmp.sh causing CKI sporadic failures Message-ID: References: Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Mon, Oct 12, 2026 at 06:23:32PM +0530, Prasenjit Mukherjee wrote: > CKI reports sporadic failures in icmp.sh, Davide suggests this might be > caused by a race condition where tcpdump starts capturing after the last of > expected ICMP unreachable packets have been sent. > Fix this replacing tcpdump with a tc flower filter that > matches ICMP Destination Unreachable (type 3, code 0), > and match on act_gact counters instead. > This will remove any race condition to appear. > > Fixes: 7e9838b7915e2 ("selftests/net: Add icmp.sh for testing ICMP dummy address responses") > CC: Toke Høiland-Jørgensen > Suggested-by: Davide Caratti > Reviewed-by: Davide Caratti > Reported-by: CKI Project > Closes: https://datawarehouse.cki-project.org/issue/3658 > Signed-off-by: Prasenjit Mukherjee Reviewed-by: Antoine Tenart > --- > tools/testing/selftests/net/icmp.sh | 32 ++++++++++++++--------------- > 1 file changed, 16 insertions(+), 16 deletions(-) > > diff --git a/tools/testing/selftests/net/icmp.sh b/tools/testing/selftests/net/icmp.sh > index 824cb0e35eff..0714e8b34d12 100755 > --- a/tools/testing/selftests/net/icmp.sh > +++ b/tools/testing/selftests/net/icmp.sh > @@ -27,11 +27,8 @@ PINGADDR=172.16.1.1 > RT2=172.16.0.0/24 > H2_IP6=2001:db8:1::2 > > -TMPFILE=$(mktemp) > - > cleanup() > { > - rm -f "$TMPFILE" > cleanup_ns $NS1 $NS2 > } > > @@ -52,21 +49,24 @@ ip -netns $NS2 route add $RT2 via inet6 $H1_IP6 > > # Make sure ns2 will respond with ICMP unreachable > ip netns exec $NS2 sysctl -qw net.ipv4.icmp_ratelimit=0 net.ipv4.ip_forward=1 > +# Install tc flower filter to count ICMP unreachable from 192.0.0.8 > +ip netns exec $NS1 tc qdisc add dev veth0 clsact > +ip netns exec $NS1 tc filter add dev veth0 ingress \ > + protocol ip pref 1 handle 1 flower \ > + src_ip 192.0.0.8 ip_proto icmp type 3 code 0 \ > + action pass > > -# Run the test - a ping runs in the background, and we capture ICMP responses > -# with tcpdump; -c 1 means it should exit on the first ping, but add a timeout > -# in case something goes wrong > -ip netns exec $NS1 ping -w 3 -i 0.5 $PINGADDR >/dev/null & > -ip netns exec $NS1 timeout 10 tcpdump -tpni veth0 -c 1 'icmp and icmp[icmptype] != icmp-echo' > $TMPFILE 2>/dev/null > +# Send ping to trigger ICMP unreachable from ns2 > +ip netns exec $NS1 ping -c 1 $PINGADDR >/dev/null 2>&1 > > -# Parse response and check for dummy address > -# tcpdump output looks like: > -# IP 192.0.0.8 > 172.16.0.1: ICMP net 172.16.1.1 unreachable, length 92 > -RESP_IP=$(awk '{print $2}' < $TMPFILE) > -if [[ "$RESP_IP" != "192.0.0.8" ]]; then > - echo "FAIL - got ICMP response from $RESP_IP, should be 192.0.0.8" > - exit 1 > -else > +# Verify ICMP unreachable was received from dummy address 192.0.0.8 per RFC7600 > +COUNT=$(ip netns exec $NS1 tc -j -s filter show dev veth0 ingress \ > + | jq '.[1].options.actions[].stats.packets') > + > +if [[ "$COUNT" -eq 1 ]]; then > echo "OK" > exit 0 > +else > + echo "FAIL - expected 1 ICMP unreachable from 192.0.0.8, got $COUNT" > + exit 1 > fi > -- > 2.55.0 >