Re: [PATCH rcu/dev 3/3] net: Use call_rcu_flush() for dst_destroy_rcu

[Eric Dumazet]

On Wed, Nov 16, 2022 at 7:16 PM Joel Fernandes (Google)
<joel@xxxxxxxxxxxxxxxxx> wrote:
>
> In a networking test on ChromeOS, we find that using the new CONFIG_RCU_LAZY
> causes a networking test to fail in the teardown phase.
>
> The failure happens during: ip netns del <name>

And ? What happens then next ?

>
> Using ftrace, I found the callbacks it was queuing which this series fixes. Use
> call_rcu_flush() to revert to the old behavior. With that, the test passes.

What is this test about ? What barrier was used to make it not flaky ?

Was it depending on some undocumented RCU behavior ?

Maybe adding a sysctl to force the flush would be better for functional tests ?

I would rather change the test(s), than adding call_rcu_flush(),
adding merge conflicts to future backports.