From: Vladimir Vdovin <deliran@verdict.gg>
To: netdev@vger.kernel.org
Cc: dsahern@kernel.org, idosch@nvidia.com, davem@davemloft.net,
edumazet@kernel.org, kuba@kernel.org, pabeni@redhat.com,
horms@kernel.org, shuah@kernel.org,
linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org,
Vladimir Vdovin <deliran@verdict.gg>
Subject: [PATCH net-next 2/2] selftests: net: pmtu: Add IPv6 multipath exceptions test
Date: Sun, 18 Oct 2026 00:05:08 +0300 [thread overview]
Message-ID: <20261017210508.71849-3-deliran@verdict.gg> (raw)
In-Reply-To: <20261017210508.71849-1-deliran@verdict.gg>
Make pmtu_ipv4_mp_exceptions family agnostic and add
pmtu_ipv6_mp_exceptions: one oversized ping over a multipath route
must leave PMTU exceptions on both paths.
Without the preceding fix the IPv6 test fails with both legacy
nexthops and nexthop objects:
PMTU exception wasn't created after exceeding MTU (veth_A-R2)
Signed-off-by: Vladimir Vdovin <deliran@verdict.gg>
---
tools/testing/selftests/net/pmtu.sh | 162 +++++++++++++++++++++-------
1 file changed, 124 insertions(+), 38 deletions(-)
diff --git a/tools/testing/selftests/net/pmtu.sh b/tools/testing/selftests/net/pmtu.sh
index c7cd271714ef..9ff46708fa03 100755
--- a/tools/testing/selftests/net/pmtu.sh
+++ b/tools/testing/selftests/net/pmtu.sh
@@ -203,6 +203,9 @@
# on host A and B on lo reachable via both routers. Host A and B
# addresses have multipath routes to each other, b_r1 mtu = 1500.
# Check that PMTU exceptions are created for both paths.
+#
+# - pmtu_ipv6_mp_exceptions
+# Same as above but with IPv6
source lib.sh
@@ -272,7 +275,8 @@ tests="
list_flush_ipv6_exception ipv6: list and flush cached exceptions 1
pmtu_ipv4_route_change ipv4: PMTU exception w/route replace 1
pmtu_ipv6_route_change ipv6: PMTU exception w/route replace 1
- pmtu_ipv4_mp_exceptions ipv4: PMTU multipath nh exceptions 1"
+ pmtu_ipv4_mp_exceptions ipv4: PMTU multipath nh exceptions 1
+ pmtu_ipv6_mp_exceptions ipv6: PMTU multipath nh exceptions 1"
# Addressing and routing for tests with routers: four network segments, with
# index SEGMENT between 1 and 4, a common prefix (PREFIX4 or PREFIX6) and an
@@ -352,6 +356,9 @@ tunnel6_mask="64"
host4_a_addr="192.168.99.99"
host4_b_addr="192.168.88.88"
+host6_a_addr="fc00:1000::a"
+host6_b_addr="fc00:1001::b"
+
dummy6_0_prefix="fc00:1000::"
dummy6_1_prefix="fc00:1001::"
dummy6_mask="64"
@@ -994,49 +1001,112 @@ setup_ovs_bridge() {
}
setup_multipath_new() {
- # Set up host A with multipath routes to host B host4_b_addr
- run_cmd ${ns_a} ip addr add ${host4_a_addr} dev lo
- run_cmd ${ns_a} ip nexthop add id 401 via ${prefix4}.${a_r1}.2 dev veth_A-R1
- run_cmd ${ns_a} ip nexthop add id 402 via ${prefix4}.${a_r2}.2 dev veth_A-R2
- run_cmd ${ns_a} ip nexthop add id 403 group 401/402
- run_cmd ${ns_a} ip route add ${host4_b_addr} src ${host4_a_addr} nhid 403
+ family=${1}
- # Set up host B with multipath routes to host A host4_a_addr
- run_cmd ${ns_b} ip addr add ${host4_b_addr} dev lo
- run_cmd ${ns_b} ip nexthop add id 401 via ${prefix4}.${b_r1}.2 dev veth_B-R1
- run_cmd ${ns_b} ip nexthop add id 402 via ${prefix4}.${b_r2}.2 dev veth_B-R2
- run_cmd ${ns_b} ip nexthop add id 403 group 401/402
- run_cmd ${ns_b} ip route add ${host4_a_addr} src ${host4_b_addr} nhid 403
+ if [ ${family} -eq 4 ]; then
+ host_a_addr=${host4_a_addr}
+ host_b_addr=${host4_b_addr}
+ nh_a_r1=${prefix4}.${a_r1}.2
+ nh_a_r2=${prefix4}.${a_r2}.2
+ nh_b_r1=${prefix4}.${b_r1}.2
+ nh_b_r2=${prefix4}.${b_r2}.2
+ else
+ host_a_addr=${host6_a_addr}
+ host_b_addr=${host6_b_addr}
+ nh_a_r1=${prefix6}:${a_r1}::2
+ nh_a_r2=${prefix6}:${a_r2}::2
+ nh_b_r1=${prefix6}:${b_r1}::2
+ nh_b_r2=${prefix6}:${b_r2}::2
+ fi
+
+ # Set up host A with multipath routes to host B host_b_addr
+ run_cmd ${ns_a} ip addr add ${host_a_addr} dev lo
+ run_cmd ${ns_a} ip nexthop add id ${family}01 via ${nh_a_r1} dev veth_A-R1
+ run_cmd ${ns_a} ip nexthop add id ${family}02 via ${nh_a_r2} dev veth_A-R2
+ run_cmd ${ns_a} ip nexthop add id ${family}03 group ${family}01/${family}02
+ run_cmd ${ns_a} ip route add ${host_b_addr} src ${host_a_addr} nhid ${family}03
+
+ # Set up host B with multipath routes to host A host_a_addr
+ run_cmd ${ns_b} ip addr add ${host_b_addr} dev lo
+ run_cmd ${ns_b} ip nexthop add id ${family}01 via ${nh_b_r1} dev veth_B-R1
+ run_cmd ${ns_b} ip nexthop add id ${family}02 via ${nh_b_r2} dev veth_B-R2
+ run_cmd ${ns_b} ip nexthop add id ${family}03 group ${family}01/${family}02
+ run_cmd ${ns_b} ip route add ${host_a_addr} src ${host_b_addr} nhid ${family}03
}
setup_multipath_old() {
- # Set up host A with multipath routes to host B host4_b_addr
- run_cmd ${ns_a} ip addr add ${host4_a_addr} dev lo
- run_cmd ${ns_a} ip route add ${host4_b_addr} \
- src ${host4_a_addr} \
- nexthop via ${prefix4}.${a_r1}.2 weight 1 \
- nexthop via ${prefix4}.${a_r2}.2 weight 1
+ family=${1}
- # Set up host B with multipath routes to host A host4_a_addr
- run_cmd ${ns_b} ip addr add ${host4_b_addr} dev lo
- run_cmd ${ns_b} ip route add ${host4_a_addr} \
- src ${host4_b_addr} \
- nexthop via ${prefix4}.${b_r1}.2 weight 1 \
- nexthop via ${prefix4}.${b_r2}.2 weight 1
+ if [ ${family} -eq 4 ]; then
+ host_a_addr=${host4_a_addr}
+ host_b_addr=${host4_b_addr}
+ nh_a_r1=${prefix4}.${a_r1}.2
+ nh_a_r2=${prefix4}.${a_r2}.2
+ nh_b_r1=${prefix4}.${b_r1}.2
+ nh_b_r2=${prefix4}.${b_r2}.2
+ else
+ host_a_addr=${host6_a_addr}
+ host_b_addr=${host6_b_addr}
+ nh_a_r1=${prefix6}:${a_r1}::2
+ nh_a_r2=${prefix6}:${a_r2}::2
+ nh_b_r1=${prefix6}:${b_r1}::2
+ nh_b_r2=${prefix6}:${b_r2}::2
+ fi
+
+ # Set up host A with multipath routes to host B host_b_addr
+ run_cmd ${ns_a} ip addr add ${host_a_addr} dev lo
+ run_cmd ${ns_a} ip route add ${host_b_addr} \
+ src ${host_a_addr} \
+ nexthop via ${nh_a_r1} weight 1 \
+ nexthop via ${nh_a_r2} weight 1
+
+ # Set up host B with multipath routes to host A host_a_addr
+ run_cmd ${ns_b} ip addr add ${host_b_addr} dev lo
+ run_cmd ${ns_b} ip route add ${host_a_addr} \
+ src ${host_b_addr} \
+ nexthop via ${nh_b_r1} weight 1 \
+ nexthop via ${nh_b_r2} weight 1
}
+
setup_multipath() {
+ family="$1"
+
+ if [ ${family} -eq 4 ]; then
+ host_a_addr=${host4_a_addr}
+ host_b_addr=${host4_b_addr}
+ nh_r1_a=${prefix4}.${a_r1}.1
+ nh_r1_b=${prefix4}.${b_r1}.1
+ nh_r2_a=${prefix4}.${a_r2}.1
+ nh_r2_b=${prefix4}.${b_r2}.1
+ else
+ host_a_addr=${host6_a_addr}
+ host_b_addr=${host6_b_addr}
+ nh_r1_a=${prefix6}:${a_r1}::1
+ nh_r1_b=${prefix6}:${b_r1}::1
+ nh_r2_a=${prefix6}:${a_r2}::1
+ nh_r2_b=${prefix6}:${b_r2}::1
+ fi
+
if [ "$USE_NH" = "yes" ]; then
- setup_multipath_new
+ setup_multipath_new ${family}
else
- setup_multipath_old
+ setup_multipath_old ${family}
fi
# Set up routers with routes to dummies
- run_cmd ${ns_r1} ip route add ${host4_a_addr} via ${prefix4}.${a_r1}.1
- run_cmd ${ns_r2} ip route add ${host4_a_addr} via ${prefix4}.${a_r2}.1
- run_cmd ${ns_r1} ip route add ${host4_b_addr} via ${prefix4}.${b_r1}.1
- run_cmd ${ns_r2} ip route add ${host4_b_addr} via ${prefix4}.${b_r2}.1
+ run_cmd ${ns_r1} ip route add ${host_a_addr} via ${nh_r1_a}
+ run_cmd ${ns_r2} ip route add ${host_a_addr} via ${nh_r2_a}
+ run_cmd ${ns_r1} ip route add ${host_b_addr} via ${nh_r1_b}
+ run_cmd ${ns_r2} ip route add ${host_b_addr} via ${nh_r2_b}
+}
+
+setup_multipath4() {
+ setup_multipath 4
+}
+
+setup_multipath6() {
+ setup_multipath 6
}
setup() {
@@ -2377,8 +2447,18 @@ test_pmtu_ipv6_route_change() {
test_pmtu_ipvX_route_change 6
}
-test_pmtu_ipv4_mp_exceptions() {
- setup namespaces routing multipath || return $ksft_skip
+test_pmtu_ipvX_mp_exceptions() {
+ family=${1}
+
+ if [ ${family} -eq 4 ]; then
+ ping=ping
+ dst="${host4_b_addr}"
+ else
+ ping=${ping6}
+ dst="${host6_b_addr}"
+ fi
+
+ setup namespaces routing multipath${family} || return $ksft_skip
trace "${ns_a}" veth_A-R1 "${ns_r1}" veth_R1-A \
"${ns_r1}" veth_R1-B "${ns_b}" veth_B-R1 \
@@ -2395,18 +2475,24 @@ test_pmtu_ipv4_mp_exceptions() {
mtu "${ns_r2}" veth_R2-A 2000
mtu "${ns_r2}" veth_R2-B 1500
mtu "${ns_b}" veth_B-R2 1500
-
# Ping and expect two nexthop exceptions for two routes
- run_cmd ${ns_a} ping -q -M want -i 0.1 -c 1 -s 1800 "${host4_b_addr}"
+ run_cmd ${ns_a} ${ping} -q -M want -i 0.1 -c 1 -s 1800 "${dst}"
# Check that exceptions have been created with the correct PMTU
- pmtu_a_R1="$(route_get_dst_pmtu_from_exception "${ns_a}" "${host4_b_addr}" oif veth_A-R1)"
- pmtu_a_R2="$(route_get_dst_pmtu_from_exception "${ns_a}" "${host4_b_addr}" oif veth_A-R2)"
-
+ pmtu_a_R1="$(route_get_dst_pmtu_from_exception "${ns_a}" "${dst}" oif veth_A-R1)"
+ pmtu_a_R2="$(route_get_dst_pmtu_from_exception "${ns_a}" "${dst}" oif veth_A-R2)"
check_pmtu_value "1500" "${pmtu_a_R1}" "exceeding MTU (veth_A-R1)" || return 1
check_pmtu_value "1500" "${pmtu_a_R2}" "exceeding MTU (veth_A-R2)" || return 1
}
+test_pmtu_ipv4_mp_exceptions() {
+ test_pmtu_ipvX_mp_exceptions 4
+}
+
+test_pmtu_ipv6_mp_exceptions() {
+ test_pmtu_ipvX_mp_exceptions 6
+}
+
usage() {
echo
echo "$0 [OPTIONS] [TEST]..."
--
2.56.0
next prev parent reply other threads:[~2026-10-17 21:05 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-17 21:05 [PATCH net-next 0/2] ipv6: Cache pmtu on all paths of a multipath route Vladimir Vdovin
2026-10-17 21:05 ` [PATCH net-next 1/2] ipv6: Cache pmtu for " Vladimir Vdovin
2026-10-18 22:06 ` netdev-bot+sashiko
2026-10-17 21:05 ` Vladimir Vdovin [this message]
2026-10-18 13:47 ` [PATCH net-next 0/2] ipv6: Cache pmtu on " Ido Schimmel
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