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

[PATCH] 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_dev() after corresponding simple_if_init() on physical
interfaces to make sure auto-negotiation has been completed and test
packets will not be lost because of the race against link establishment.

The wait has to be done in each individual test because the interfaces
have to be brough up first and only then we can wait for link (not
individually, because they are expected to be looped in pairs).

Fixes: 90b9566aa5cd3f ("selftests: forwarding: add a test for local_termination.sh")
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@siemens.com>
---
 .../selftests/net/forwarding/local_termination.sh      | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/tools/testing/selftests/net/forwarding/local_termination.sh b/tools/testing/selftests/net/forwarding/local_termination.sh
index ecd34f364125c..369c8b2c1f4a2 100755
--- a/tools/testing/selftests/net/forwarding/local_termination.sh
+++ b/tools/testing/selftests/net/forwarding/local_termination.sh
@@ -430,6 +430,8 @@ standalone()
 	h1_create
 	h2_create
 	macvlan_create $h2
+	setup_wait_dev $h1
+	setup_wait_dev $h2
 
 	run_test $h1 $h2 $skip_ptp $no_unicast_flt "$h2"
 
@@ -448,6 +450,8 @@ test_bridge()
 	bridge_create $vlan_filtering
 	simple_if_init br0 $H2_IPV4/24 $H2_IPV6/64
 	macvlan_create br0
+	setup_wait_dev $h1
+	setup_wait_dev $h2
 
 	run_test $h1 br0 $skip_ptp $no_unicast_flt \
 		"vlan_filtering=$vlan_filtering bridge"
@@ -480,6 +484,8 @@ test_vlan()
 	h1_vlan_create
 	h2_vlan_create
 	macvlan_create $h2.100
+	setup_wait_dev $h1
+	setup_wait_dev $h2
 
 	run_test $h1.100 $h2.100 $skip_ptp $no_unicast_flt "VLAN upper"
 
@@ -505,6 +511,8 @@ vlan_over_bridged_port()
 	h2_vlan_create
 	bridge_create $vlan_filtering
 	macvlan_create $h2.100
+	setup_wait_dev $h1
+	setup_wait_dev $h2
 
 	run_test $h1.100 $h2.100 $skip_ptp $no_unicast_flt \
 		"VLAN over vlan_filtering=$vlan_filtering bridged port"
@@ -536,6 +544,8 @@ vlan_over_bridge()
 	simple_if_init br0
 	vlan_create br0 100 vbr0 $H2_IPV4/24 $H2_IPV6/64
 	macvlan_create br0.100
+	setup_wait_dev $h1
+	setup_wait_dev $h2
 
 	if [ $vlan_filtering = 1 ]; then
 		bridge vlan add dev $h2 vid 100 master
-- 
2.51.1

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

[Vladimir Oltean]

On Tue, Nov 04, 2025 at 07:17:21AM +0100, A. Sverdlin 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.

Yes, sorry, dropping the link is an unfortunate, undesirable and
unaccounted for side effect of simple_if_init and simple_if_fini,
mainly used for moving the IP addresses from the physical to the various
virtual upper interfaces.

> 
> Use setup_wait_dev() after corresponding simple_if_init() on physical
> interfaces to make sure auto-negotiation has been completed and test
> packets will not be lost because of the race against link establishment.
> 
> The wait has to be done in each individual test because the interfaces
> have to be brough up first and only then we can wait for link (not
> individually, because they are expected to be looped in pairs).
> 
> Fixes: 90b9566aa5cd3f ("selftests: forwarding: add a test for local_termination.sh")
> Signed-off-by: Alexander Sverdlin <alexander.sverdlin@siemens.com>
> ---
>  .../selftests/net/forwarding/local_termination.sh      | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/tools/testing/selftests/net/forwarding/local_termination.sh b/tools/testing/selftests/net/forwarding/local_termination.sh
> index ecd34f364125c..369c8b2c1f4a2 100755
> --- a/tools/testing/selftests/net/forwarding/local_termination.sh
> +++ b/tools/testing/selftests/net/forwarding/local_termination.sh
> @@ -430,6 +430,8 @@ standalone()
>  	h1_create
>  	h2_create
>  	macvlan_create $h2
> +	setup_wait_dev $h1
> +	setup_wait_dev $h2
>  
>  	run_test $h1 $h2 $skip_ptp $no_unicast_flt "$h2"
>  
> @@ -448,6 +450,8 @@ test_bridge()
>  	bridge_create $vlan_filtering
>  	simple_if_init br0 $H2_IPV4/24 $H2_IPV6/64
>  	macvlan_create br0
> +	setup_wait_dev $h1
> +	setup_wait_dev $h2
>  
>  	run_test $h1 br0 $skip_ptp $no_unicast_flt \
>  		"vlan_filtering=$vlan_filtering bridge"
> @@ -480,6 +484,8 @@ test_vlan()
>  	h1_vlan_create
>  	h2_vlan_create
>  	macvlan_create $h2.100
> +	setup_wait_dev $h1
> +	setup_wait_dev $h2
>  
>  	run_test $h1.100 $h2.100 $skip_ptp $no_unicast_flt "VLAN upper"
>  
> @@ -505,6 +511,8 @@ vlan_over_bridged_port()
>  	h2_vlan_create
>  	bridge_create $vlan_filtering
>  	macvlan_create $h2.100
> +	setup_wait_dev $h1
> +	setup_wait_dev $h2
>  
>  	run_test $h1.100 $h2.100 $skip_ptp $no_unicast_flt \
>  		"VLAN over vlan_filtering=$vlan_filtering bridged port"
> @@ -536,6 +544,8 @@ vlan_over_bridge()
>  	simple_if_init br0
>  	vlan_create br0 100 vbr0 $H2_IPV4/24 $H2_IPV6/64
>  	macvlan_create br0.100
> +	setup_wait_dev $h1
> +	setup_wait_dev $h2
>  
>  	if [ $vlan_filtering = 1 ]; then
>  		bridge vlan add dev $h2 vid 100 master
> -- 
> 2.51.1
>

Functionally I have nothing against this change.

Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>

Two ideas to minimize the delta in a more obviously correct way.
They can perhaps be implemented together, independently of one another,
or not at all:

- setup_wait() could be used directly, as it waits for $NUM_NETIFS, aka
  $h1 and $h2.
- There is no case where run_test() does not need a prior setup_wait()
  call, so it can just as well be placed as the first thing of that
  function.

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

[Paolo Abeni]

On 11/5/25 10:31 PM, Vladimir Oltean wrote:
> Functionally I have nothing against this change.
> 
> Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
> 
> Two ideas to minimize the delta in a more obviously correct way.
> They can perhaps be implemented together, independently of one another,
> or not at all:
> 
> - setup_wait() could be used directly, as it waits for $NUM_NETIFS, aka
>   $h1 and $h2.
> - There is no case where run_test() does not need a prior setup_wait()
>   call, so it can just as well be placed as the first thing of that
>   function.

I think both suggestions make a lot of sense, @Alexander: please send
and updated version including them. You can retain Vladimir's RB tag.

Thanks,

Paolo