selftests: forwarding: vxlan_bridge_1q_mc_ul: Fix flakiness
Subsystems (4)
cover selftests: forwarding: vxlan_bridge_1q_mc_ul: Fix flakiness
The net/forwarding/vxlan_bridge_1q_mc_ul selftest runs an overlay traffic, forwarded over a multicast-routed VXLAN underlay. In order to determine whether packets reach their intended destination, it uses a TC match. For convenience, it uses a flower match, which however does not allow matching on the encapsulated packet. So various service traffic ends up being indistinguishable from the test packets, and ends up confusing the test. To alleviate the problem, the test uses sleep to allow the necessary service traffic to run and clear the channel, before running the test traffic. This worked for a while, but lately we have nevertheless seen flakiness of the test in the CI.
In this patchset, first generalize tc_rule_stats_get() to support u32 in patch #1, then in patch #2 convert the test to use u32 to allow parsing deeper into the packet, and in #3 drop the now-unnecessary sleep.
Petr Machata (3):
selftests: net: lib: tc_rule_stats_get(): Don't hard-code array index
selftests: forwarding: vxlan_bridge_1q_mc_ul: Fix flakiness
selftests: forwarding: vxlan_bridge_1q_mc_ul: Drop useless sleeping
tools/testing/selftests/net/forwarding/config | 1 + .../net/forwarding/vxlan_bridge_1q_mc_ul.sh | 76 ++++++++----------- tools/testing/selftests/net/lib.sh | 3 +- 3 files changed, 34 insertions(+), 46 deletions(-)
Signature · 1 line
2.51.1
PATCH 1/3 selftests: net: lib: tc_rule_stats_get(): Don't hard-code array index
Flower is commonly used to match on packets in many bash-based selftests. A dump of a flower filter including statistics looks something like this:
[
{
"protocol": "all",
"pref": 49152,
"kind": "flower",
"chain": 0
},
{
...
"options": {
...
"actions": [
{
...
"stats": {
"bytes": 0,
"packets": 0,
"drops": 0,
"overlimits": 0,
"requeues": 0,
"backlog": 0,
"qlen": 0
}
}
]
} }
]
The JQ query in the helper function tc_rule_stats_get() assumes this form and looks for the second element of the array.
However, a dump of a u32 filter looks like this:
[
{
"protocol": "all",
"pref": 49151,
"kind": "u32",
"chain": 0
},
{
"protocol": "all",
"pref": 49151,
"kind": "u32",
"chain": 0,
"options": {
"fh": "800:",
"ht_divisor": 1
}
},
{
...
"options": {
...
"actions": [
{
...
"stats": {
"bytes": 0,
"packets": 0,
"drops": 0,
"overlimits": 0,
"requeues": 0,
"backlog": 0,
"qlen": 0
}
}
]
} },
]
There's an extra element which the JQ query ends up choosing.
Instead of hard-coding a particular index, look for the entry on which a selector .options.actions yields anything.
--- tools/testing/selftests/net/lib.sh | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
tools/testing/selftests/net/lib.sh +2 -1
@@ -280,7 +280,8 @@ tc_rule_stats_get() local selector=${1:-.packets}; shift tc -j -s filter show dev $dev $dir pref $pref \ - | jq ".[1].options.actions[].stats$selector" + | jq ".[] | select(.options.actions) | + .options.actions[].stats$selector" } tc_rule_handle_stats_get()
Signature · 1 line
2.51.1
PATCH 2/3 selftests: forwarding: vxlan_bridge_1q_mc_ul: Fix flakiness
In reply to Petr MachataThis test runs an overlay traffic, forwarded over a multicast-routed VXLAN underlay. In order to determine whether packets reach their intended destination, it uses a TC match. For convenience, it uses a flower match, which however does not allow matching on the encapsulated packet. So various service traffic ends up being indistinguishable from the test packets, and ends up confusing the test. To alleviate the problem, the test uses sleep to allow the necessary service traffic to run and clear the channel, before running the test traffic. This worked for a while, but lately we have nevertheless seen flakiness of the test in the CI.
Fix the issue by using u32 to match the encapsulated packet as well. The confusing packets seem to always be IPv6 multicast listener reports. Realistically they could be ARP or other ICMP6 traffic as well. Therefore look for ethertype IPv4 in the IPv4 traffic test, and for IPv6 / UDP combination in the IPv6 traffic test.
--- tools/testing/selftests/net/forwarding/config | 1 + .../net/forwarding/vxlan_bridge_1q_mc_ul.sh | 13 +++++++++---- 2 files changed, 10 insertions(+), 4 deletions(-)
tools/testing/selftests/net/forwarding/config +1 -0
@@ -29,6 +29,7 @@ CONFIG_NET_ACT_VLAN=m CONFIG_NET_CLS_BASIC=m CONFIG_NET_CLS_FLOWER=m CONFIG_NET_CLS_MATCHALL=m +CONFIG_NET_CLS_U32=m CONFIG_NET_EMATCH=y CONFIG_NET_EMATCH_META=m CONFIG_NETFILTER=y
tools/testing/selftests/net/forwarding/vxlan_bridge_1q_mc_ul.sh +9 -4
@@ -138,13 +138,18 @@ install_capture() defer tc qdisc del dev "$dev" clsact tc filter add dev "$dev" ingress proto ip pref 104 \ - flower skip_hw ip_proto udp dst_port "$VXPORT" \ - action pass + u32 match ip protocol 0x11 0xff \ + match u16 "$VXPORT" 0xffff at 0x16 \ + match u16 0x0800 0xffff at 0x30 \ + action pass defer tc filter del dev "$dev" ingress proto ip pref 104 tc filter add dev "$dev" ingress proto ipv6 pref 106 \ - flower skip_hw ip_proto udp dst_port "$VXPORT" \ - action pass + u32 match ip6 protocol 0x11 0xff \ + match u16 "$VXPORT" 0xffff at 0x2a \ + match u16 0x86dd 0xffff at 0x44 \ + match u8 0x11 0xff at 0x4c \ + action pass defer tc filter del dev "$dev" ingress proto ipv6 pref 106 }
Signature · 1 line
2.51.1
PATCH 3/3 selftests: forwarding: vxlan_bridge_1q_mc_ul: Drop useless sleeping
In reply to Petr MachataAfter fixing traffic matching in the previous patch, the test does not need to use the sleep anymore. So drop vx_wait() altogether, migrate all callers of vx{10,20}_create_wait() to the corresponding _create(), and drop the now unused _create_wait() helpers.
--- .../net/forwarding/vxlan_bridge_1q_mc_ul.sh | 63 +++++++------------ 1 file changed, 22 insertions(+), 41 deletions(-)
tools/testing/selftests/net/forwarding/vxlan_bridge_1q_mc_ul.sh +22 -41
@@ -253,13 +253,6 @@ vx_create() } export -f vx_create -vx_wait() -{ - # Wait for all the ARP, IGMP etc. noise to settle down so that the - # tunnel is clear for measurements. - sleep 10 -} - vx10_create() { vx_create vx10 10 id 1000 "$@"
@@ -272,18 +265,6 @@ vx20_create() } export -f vx20_create -vx10_create_wait() -{ - vx10_create "$@" - vx_wait -} - -vx20_create_wait() -{ - vx20_create "$@" - vx_wait -} - ns_init_common() { local ns=$1; shift
@@ -559,7 +540,7 @@ ipv4_nomcroute() # Install a misleading (S,G) rule to attempt to trick the system into # pushing the packets elsewhere. adf_install_broken_sg - vx10_create_wait local 192.0.2.100 group "$GROUP4" dev "$swp2" + vx10_create local 192.0.2.100 group "$GROUP4" dev "$swp2" do_test 4 10 0 "IPv4 nomcroute" }
@@ -567,7 +548,7 @@ ipv6_nomcroute() { # Like for IPv4, install a misleading (S,G). adf_install_broken_sg - vx20_create_wait local 2001:db8:4::1 group "$GROUP6" dev "$swp2" + vx20_create local 2001:db8:4::1 group "$GROUP6" dev "$swp2" do_test 6 10 0 "IPv6 nomcroute" }
@@ -586,35 +567,35 @@ ipv6_nomcroute_rx() ipv4_mcroute() { adf_install_sg - vx10_create_wait local 192.0.2.100 group "$GROUP4" dev "$IPMR" mcroute + vx10_create local 192.0.2.100 group "$GROUP4" dev "$IPMR" mcroute do_test 4 10 10 "IPv4 mcroute" } ipv6_mcroute() { adf_install_sg - vx20_create_wait local 2001:db8:4::1 group "$GROUP6" dev "$IPMR" mcroute + vx20_create local 2001:db8:4::1 group "$GROUP6" dev "$IPMR" mcroute do_test 6 10 10 "IPv6 mcroute" } ipv4_mcroute_rx() { adf_install_sg - vx10_create_wait local 192.0.2.100 group "$GROUP4" dev "$IPMR" mcroute + vx10_create local 192.0.2.100 group "$GROUP4" dev "$IPMR" mcroute ipv4_do_test_rx 0 "IPv4 mcroute ping" } ipv6_mcroute_rx() { adf_install_sg - vx20_create_wait local 2001:db8:4::1 group "$GROUP6" dev "$IPMR" mcroute + vx20_create local 2001:db8:4::1 group "$GROUP6" dev "$IPMR" mcroute ipv6_do_test_rx 0 "IPv6 mcroute ping" } ipv4_mcroute_changelink() { adf_install_sg - vx10_create_wait local 192.0.2.100 group "$GROUP4" dev "$IPMR" + vx10_create local 192.0.2.100 group "$GROUP4" dev "$IPMR" ip link set dev vx10 type vxlan mcroute sleep 1 do_test 4 10 10 "IPv4 mcroute changelink"
@@ -623,7 +604,7 @@ ipv4_mcroute_changelink() ipv6_mcroute_changelink() { adf_install_sg - vx20_create_wait local 2001:db8:4::1 group "$GROUP6" dev "$IPMR" mcroute + vx20_create local 2001:db8:4::1 group "$GROUP6" dev "$IPMR" mcroute ip link set dev vx20 type vxlan mcroute sleep 1 do_test 6 10 10 "IPv6 mcroute changelink"
@@ -632,47 +613,47 @@ ipv6_mcroute_changelink() ipv4_mcroute_starg() { adf_install_starg - vx10_create_wait local 192.0.2.100 group "$GROUP4" dev "$IPMR" mcroute + vx10_create local 192.0.2.100 group "$GROUP4" dev "$IPMR" mcroute do_test 4 10 10 "IPv4 mcroute (*,G)" } ipv6_mcroute_starg() { adf_install_starg - vx20_create_wait local 2001:db8:4::1 group "$GROUP6" dev "$IPMR" mcroute + vx20_create local 2001:db8:4::1 group "$GROUP6" dev "$IPMR" mcroute do_test 6 10 10 "IPv6 mcroute (*,G)" } ipv4_mcroute_starg_rx() { adf_install_starg - vx10_create_wait local 192.0.2.100 group "$GROUP4" dev "$IPMR" mcroute + vx10_create local 192.0.2.100 group "$GROUP4" dev "$IPMR" mcroute ipv4_do_test_rx 0 "IPv4 mcroute (*,G) ping" } ipv6_mcroute_starg_rx() { adf_install_starg - vx20_create_wait local 2001:db8:4::1 group "$GROUP6" dev "$IPMR" mcroute + vx20_create local 2001:db8:4::1 group "$GROUP6" dev "$IPMR" mcroute ipv6_do_test_rx 0 "IPv6 mcroute (*,G) ping" } ipv4_mcroute_noroute() { - vx10_create_wait local 192.0.2.100 group "$GROUP4" dev "$IPMR" mcroute + vx10_create local 192.0.2.100 group "$GROUP4" dev "$IPMR" mcroute do_test 4 0 0 "IPv4 mcroute, no route" } ipv6_mcroute_noroute() { - vx20_create_wait local 2001:db8:4::1 group "$GROUP6" dev "$IPMR" mcroute + vx20_create local 2001:db8:4::1 group "$GROUP6" dev "$IPMR" mcroute do_test 6 0 0 "IPv6 mcroute, no route" } ipv4_mcroute_fdb() { adf_install_sg - vx10_create_wait local 192.0.2.100 dev "$IPMR" mcroute + vx10_create local 192.0.2.100 dev "$IPMR" mcroute bridge fdb add dev vx10 \ 00:00:00:00:00:00 self static dst "$GROUP4" via "$IPMR" do_test 4 10 10 "IPv4 mcroute FDB"
@@ -681,7 +662,7 @@ ipv4_mcroute_fdb() ipv6_mcroute_fdb() { adf_install_sg - vx20_create_wait local 2001:db8:4::1 dev "$IPMR" mcroute + vx20_create local 2001:db8:4::1 dev "$IPMR" mcroute bridge -6 fdb add dev vx20 \ 00:00:00:00:00:00 self static dst "$GROUP6" via "$IPMR" do_test 6 10 10 "IPv6 mcroute FDB"
@@ -691,7 +672,7 @@ ipv6_mcroute_fdb() ipv4_mcroute_fdb_oif0() { adf_install_sg - vx10_create_wait local 192.0.2.100 group "$GROUP4" dev "$IPMR" mcroute + vx10_create local 192.0.2.100 group "$GROUP4" dev "$IPMR" mcroute bridge fdb del dev vx10 00:00:00:00:00:00 bridge fdb add dev vx10 00:00:00:00:00:00 self static dst "$GROUP4" do_test 4 10 10 "IPv4 mcroute oif=0"
@@ -708,7 +689,7 @@ ipv6_mcroute_fdb_oif0() defer ip -6 route del table local multicast "$GROUP6/128" dev "$IPMR" adf_install_sg - vx20_create_wait local 2001:db8:4::1 group "$GROUP6" dev "$IPMR" mcroute + vx20_create local 2001:db8:4::1 group "$GROUP6" dev "$IPMR" mcroute bridge -6 fdb del dev vx20 00:00:00:00:00:00 bridge -6 fdb add dev vx20 00:00:00:00:00:00 self static dst "$GROUP6" do_test 6 10 10 "IPv6 mcroute oif=0"
@@ -721,7 +702,7 @@ ipv4_mcroute_fdb_oif0_sep() adf_install_sg_sep adf_ip_addr_add lo 192.0.2.120/28 - vx10_create_wait local 192.0.2.120 group "$GROUP4" dev "$IPMR" mcroute + vx10_create local 192.0.2.120 group "$GROUP4" dev "$IPMR" mcroute bridge fdb del dev vx10 00:00:00:00:00:00 bridge fdb add dev vx10 00:00:00:00:00:00 self static dst "$GROUP4" do_test 4 10 10 "IPv4 mcroute TX!=RX oif=0"
@@ -732,7 +713,7 @@ ipv4_mcroute_fdb_oif0_sep_rx() adf_install_sg_sep_rx lo adf_ip_addr_add lo 192.0.2.120/28 - vx10_create_wait local 192.0.2.120 group "$GROUP4" dev "$IPMR" mcroute + vx10_create local 192.0.2.120 group "$GROUP4" dev "$IPMR" mcroute bridge fdb del dev vx10 00:00:00:00:00:00 bridge fdb add dev vx10 00:00:00:00:00:00 self static dst "$GROUP4" ipv4_do_test_rx 0 "IPv4 mcroute TX!=RX oif=0 ping"
@@ -743,7 +724,7 @@ ipv4_mcroute_fdb_sep_rx() adf_install_sg_sep_rx lo adf_ip_addr_add lo 192.0.2.120/28 - vx10_create_wait local 192.0.2.120 group "$GROUP4" dev "$IPMR" mcroute + vx10_create local 192.0.2.120 group "$GROUP4" dev "$IPMR" mcroute bridge fdb del dev vx10 00:00:00:00:00:00 bridge fdb add \ dev vx10 00:00:00:00:00:00 self static dst "$GROUP4" via lo
@@ -755,7 +736,7 @@ ipv6_mcroute_fdb_sep_rx() adf_install_sg_sep_rx "X$IPMR" adf_ip_addr_add "X$IPMR" 2001:db8:5::1/64 - vx20_create_wait local 2001:db8:5::1 group "$GROUP6" dev "$IPMR" mcroute + vx20_create local 2001:db8:5::1 group "$GROUP6" dev "$IPMR" mcroute bridge -6 fdb del dev vx20 00:00:00:00:00:00 bridge -6 fdb add dev vx20 00:00:00:00:00:00 \ self static dst "$GROUP6" via "X$IPMR"
Signature · 1 line
2.51.1
This series was applied to netdev/net.git (main) by Jakub Kicinski <[email protected]>:
Hello:
This series was applied to netdev/net.git (main)
by Jakub Kicinski <[email protected]>:
Quoted 11 lines · On Tue, 9 Dec 2025 16:29:00 +0100 you wrote:
The
net/forwarding/vxlan_bridge_1q_mc_ulselftest runs an overlay traffic, forwarded over a multicast-routed VXLAN underlay. In order to determine whether packets reach their intended destination, it uses a TC match. For convenience, it uses a flower match, which however does not allow matching on the encapsulated packet. So various service traffic ends up being indistinguishable from the test packets, and ends up confusing the test. To alleviate the problem, the test uses sleep to allow the necessary service traffic to run and clear the channel, before running the test traffic. This worked for a while, but lately we have nevertheless seen flakiness of the test in the CI.
Quoted 1 line
[...]
Here is the summary with links:
- [net,1/3] selftests: net: lib: tc_rule_stats_get(): Don't hard-code array index
https://git.kernel.org/netdev/net/c/0842e34849f6 - [net,2/3] selftests: forwarding: vxlan_bridge_1q_mc_ul: Fix flakiness https://git.kernel.org/netdev/net/c/0c8b9a68b344 - [net,3/3] selftests: forwarding: vxlan_bridge_1q_mc_ul: Drop useless sleeping https://git.kernel.org/netdev/net/c/514520b34ba7
You are awesome, thank you!
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