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(-)

2.51.1