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 E1179CA6F; Wed, 2 Sep 2026 20:29:58 +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=1788381000; cv=none; b=MKVCDwZqBMZi3S6FjWg0I14ZG/W1cJXcirsTbATTG/2oPMPbJnu6jfRyGtjDDDFEBr8mpmYaLHXP0A3hrl74X1N/h8RdDTx9owqpyCnSRZESsfDTNWeAhRUTirlY/b04PHKKmhIhmTtdvNA3v6U9O7yxLmqomns1oHRhXeTgXEM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788381000; c=relaxed/simple; bh=5GZBvCsMOFsFK+rU7KztXj9UD8tznxkCHHiAEsivmks=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=PZu/Zy3O4eBjQbR/SOK4zIrz9ClfMz2H57gOnRkRzaZACNR55/IGndVACi7RakmO4scgyyUqH1uj2a97iSORJT6zKzRdPtyZpgk7D2lBppQWO8q959w7FAgPp6ixZyi8WXgZ1rOhPYI0eXuIe4MLSZ1z7kRK1efp8caOxDa8IoY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=EjMU7p5Q; 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="EjMU7p5Q" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 17ADC1F000E9; Wed, 2 Sep 2026 20:29:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788380998; bh=cGdkDE7sit6AxArVGexqh3DzsX9Gs9/f7klByuNA0IA=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=EjMU7p5Q1RdK3l4wX8IbzKHsEaVHCiB4xywxTYeHXUYGqG7quVvPk2uchitIv64yD j8blse4qdSB9ggwcNwTHDvi3MU78BmVG3Z/yyc+SOfHjMXisWhp+yfpjQPOCtqEilG NwVQLJI6aohDk686p1OD5RaUDk6a9m4ZjqG03sMpIIgVxFzhKmIulOQOKTRFCXDPyn gUSVKMBgRkk6lkqRjDH2i6Lr9PQpZAJEQYUWnfbD8dRuM1iHVdVSgpaJPP1sg42UQg q3vdKLHNiQyt4bQPoV+V/LAHR7aDCGq/jA/ZdLuQNLp4juvvzb8f1apCMfcM8pTc8r b+zpI5zg+fzxw== Message-ID: Date: Wed, 2 Sep 2026 14:29:57 -0600 Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net] selftests/net: Fix icmp.sh race between ping and tcpdump startup Content-Language: en-US To: =?UTF-8?B?UmljYXJkbyBCLiBNYXJsacOocmUgKFNVU0Up?= , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Shuah Khan , =?UTF-8?Q?Toke_H=C3=B8iland-J=C3=B8rgensen?= Cc: netdev@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org References: <20260901-selftests-net-icmp_race-v1-1-0b2a27e91a0c@marliere.net> From: David Ahern In-Reply-To: <20260901-selftests-net-icmp_race-v1-1-0b2a27e91a0c@marliere.net> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 9/1/26 8:09 AM, Ricardo B. Marlière (SUSE) wrote: > @@ -53,11 +54,21 @@ 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 > > -# 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 > +# Run the test - start tcpdump and wait for it to be capturing before > +# sending any traffic. -c 1 means it should exit on the first ping, but add > +# a timeout in case something goes wrong > +ip netns exec $NS1 timeout 10 tcpdump -tpni veth0 -c 1 \ > + 'icmp and icmp[icmptype] != icmp-echo' > $TMPFILE 2>$TCPDUMP_ERR & Why keep the 'timeout 10'? > +TCPDUMP_PID=$! You have the pid. You can always kill it after the ping command if it does not terminate on its own after the 1 packet is received. > +if ! slowwait 3 grep -qs "listening" "$TCPDUMP_ERR"; then > + echo "FAIL - tcpdump did not start listening" > + cat "$TCPDUMP_ERR" > + exit 1 > +fi > + > 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 > + > +wait $TCPDUMP_PID >