Re: [PATCH RESEND] selftests/futex: Order calls in futex_requeue

[André Almeida]

Hi Edward,

Thanks for your patch!

Em 03/09/2024 17:39, Edward Liaw escreveu:
> Similar to fbf4dec70277 ("selftests/futex: Order calls to
> futex_lock_pi"), which fixed a flake in futex_lock_pi due to racing
> between the parent and child threads.
>
> The same issue can occur in the futex_requeue test, because it expects
> waiterfn to make progress to futex_wait before the parent starts to
> requeue. This is mitigated by the parent sleeping for WAKE_WAIT_US, but
> it still fails occasionally. This can be reproduced by adding a sleep in
> the waiterfn before futex_wait:
>
> TAP version 13
> 1..2
> not ok 1 futex_requeue simple returned: 0
> not ok 2 futex_requeue simple returned: 0
> not ok 3 futex_requeue many returned: 0
> not ok 4 futex_requeue many returned: 0
>
> Instead, replace the sleep with barriers to make the sequencing
> explicit.

Reviewed-by: André Almeida <andrealmeid@xxxxxxxxxx>