[PATCH net v3] selftests: net: local_termination: Wait for interfaces to come up

[PATCH net v3] selftests: net: local_termination: Wait for interfaces to come up

[A. Sverdlin]

From: Alexander Sverdlin <alexander.sverdlin@siemens.com>

It seems that most of the tests prepare the interfaces once before the test
run (setup_prepare()), rely on setup_wait() to wait for link and only then
run the test(s).

local_termination brings the physical interfaces down and up during test
run but never wait for them to come up. If the auto-negotiation takes
some seconds, first test packets are being lost, which leads to
false-negative test results.

Use setup_wait() in run_test() to make sure auto-negotiation has been
completed after all simple_if_init() calls on physical interfaces and test
packets will not be lost because of the race against link establishment.

Fixes: 90b9566aa5cd3f ("selftests: forwarding: add a test for local_termination.sh")
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@siemens.com>
---
Changelog:
v3:
- moved setup_wait() from individual test groups into run_test()
v2:
- replaced "setup_wait_dev $h1; setup_wait_dev $h2" with setup_wait()
 tools/testing/selftests/net/forwarding/local_termination.sh | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tools/testing/selftests/net/forwarding/local_termination.sh b/tools/testing/selftests/net/forwarding/local_termination.sh
index ecd34f364125c..892895659c7e4 100755
--- a/tools/testing/selftests/net/forwarding/local_termination.sh
+++ b/tools/testing/selftests/net/forwarding/local_termination.sh
@@ -176,6 +176,8 @@ run_test()
 	local rcv_dmac=$(mac_get $rcv_if_name)
 	local should_receive
 
+	setup_wait
+
 	tcpdump_start $rcv_if_name
 
 	mc_route_prepare $send_if_name
-- 
2.51.1

Re: [PATCH net v3] selftests: net: local_termination: Wait for interfaces to come up

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Thu,  6 Nov 2025 17:12:09 +0100 you wrote:
> From: Alexander Sverdlin <alexander.sverdlin@siemens.com>
> 
> It seems that most of the tests prepare the interfaces once before the test
> run (setup_prepare()), rely on setup_wait() to wait for link and only then
> run the test(s).
> 
> local_termination brings the physical interfaces down and up during test
> run but never wait for them to come up. If the auto-negotiation takes
> some seconds, first test packets are being lost, which leads to
> false-negative test results.
> 
> [...]

Here is the summary with links:
  - [net,v3] selftests: net: local_termination: Wait for interfaces to come up
    https://git.kernel.org/netdev/net/c/57531b341644

You are awesome, thank you!
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