netdev - Re: [PATCH net-next v8] net: ipv4: Cache pmtu for all packet paths if multipath enabled

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Message-Id: <D5FURBXG9EC0.2MKP63RO0JXV2@verdict.gg>
Date: Thu, 07 Nov 2024 12:51:56 +0300
From: "Vladimir Vdovin" <deliran@...dict.gg>
To: "Ido Schimmel" <idosch@...sch.org>
Cc: <netdev@...r.kernel.org>, <dsahern@...nel.org>, <davem@...emloft.net>,
 <edumazet@...gle.com>, <linux-kselftest@...r.kernel.org>,
 <kuba@...nel.org>, <pabeni@...hat.com>, <shuah@...nel.org>,
 <horms@...nel.org>, <gnault@...hat.com>
Subject: Re: [PATCH net-next v8] net: ipv4: Cache pmtu for all packet paths
 if multipath enabled

On Thu Nov 7, 2024 at 12:14 PM MSK, Ido Schimmel wrote:
> On Wed, Nov 06, 2024 at 01:30:07PM +0000, Vladimir Vdovin wrote:
> > +test_pmtu_ipv4_mp_exceptions() {
> > +	setup namespaces routing multipath || return $ksft_skip
> > +
> > +	trace "${ns_a}"  veth_A-R1    "${ns_r1}" veth_R1-A \
> > +	      "${ns_r1}" veth_R1-B    "${ns_b}"  veth_B-R1 \
> > +	      "${ns_a}"  veth_A-R2    "${ns_r2}" veth_R2-A \
> > +	      "${ns_r2}" veth_R2-B    "${ns_b}"  veth_B-R2
> > +
> > +	# Set up initial MTU values
> > +	mtu "${ns_a}"  veth_A-R1 2000
> > +	mtu "${ns_r1}" veth_R1-A 2000
> > +	mtu "${ns_r1}" veth_R1-B 1500
> > +	mtu "${ns_b}"  veth_B-R1 1500
> > +
> > +	mtu "${ns_a}"  veth_A-R2 2000
> > +	mtu "${ns_r2}" veth_R2-A 2000
> > +	mtu "${ns_r2}" veth_R2-B 1500
> > +	mtu "${ns_b}"  veth_B-R2 1500
> > +
> > +	fail=0
> > +
> > +	# Ping and expect two nexthop exceptions for two routes in nh group
> > +	run_cmd ${ns_a} ping -q -M want -i 0.1 -c 1 -s 1800 "${host4_b_addr}"
> > +
> > +	# Do route lookup before checking cached exceptions.
> > +	# The following commands are needed for dst entries to be cached
> > +	# in both paths exceptions and therefore dumped to user space
> > +	# Check that exceptions have been created with the correct PMTU
> > +	pmtu="$(route_get_dst_pmtu_from_exception "${ns_a}" "${host4_b_addr}" oif veth_A-R1)"
> > +	pmtu="$(route_get_dst_pmtu_from_exception "${ns_a}" "${host4_b_addr}" oif veth_A-R2)"
>
> This overrides the first PMTU
>
> > +
> > +	check_pmtu_value "1500" "${pmtu}" "exceeding MTU (veth_A-R2)" || return 1
> > +	check_pmtu_value "1500" "${pmtu}" "exceeding MTU (veth_A-R1)" || return 1
> > +
> > +	return ${fail}
>
> And "fail" does not seem to be used anymore.
>
> Can you squash the following diff to v9?
Thanks again! Sent v9
And seems that v10 will come next day, cause I did not apply your diff and forgot to
remove fail=0 :/

>
> diff --git a/tools/testing/selftests/net/pmtu.sh b/tools/testing/selftests/net/pmtu.sh
> index 9e34b54d9c15..1b4d4c598d66 100755
> --- a/tools/testing/selftests/net/pmtu.sh
> +++ b/tools/testing/selftests/net/pmtu.sh
> @@ -2396,22 +2396,14 @@ test_pmtu_ipv4_mp_exceptions() {
>  	mtu "${ns_r2}" veth_R2-B 1500
>  	mtu "${ns_b}"  veth_B-R2 1500
>  
> -	fail=0
> -
>  	# Ping and expect two nexthop exceptions for two routes in nh group
>  	run_cmd ${ns_a} ping -q -M want -i 0.1 -c 1 -s 1800 "${host4_b_addr}"
>  
> -	# Do route lookup before checking cached exceptions.
> -	# The following commands are needed for dst entries to be cached
> -	# in both paths exceptions and therefore dumped to user space
>  	# Check that exceptions have been created with the correct PMTU
>  	pmtu="$(route_get_dst_pmtu_from_exception "${ns_a}" "${host4_b_addr}" oif veth_A-R1)"
> +	check_pmtu_value "1500" "${pmtu}" "exceeding MTU (veth_A-R1)" || return 1
>  	pmtu="$(route_get_dst_pmtu_from_exception "${ns_a}" "${host4_b_addr}" oif veth_A-R2)"
> -
>  	check_pmtu_value "1500" "${pmtu}" "exceeding MTU (veth_A-R2)" || return 1
> -	check_pmtu_value "1500" "${pmtu}" "exceeding MTU (veth_A-R1)" || return 1
> -
> -	return ${fail}
>  }
>  
>  usage() {