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From: Miguel Ojeda <ojeda@kernel.org>
To: davidgow@google.com
Cc: brendan.higgins@linux.dev,
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	Miguel Ojeda <ojeda@kernel.org>
Subject: Re: [PATCH] kunit: Fix race condition in try-catch completion
Date: Sat, 13 Apr 2024 23:04:10 +0200
Message-ID: <20240413210411.441424-1-ojeda@kernel.org>
In-Reply-To: <20240412025903.489470-1-davidgow@google.com>
References: <20240412025903.489470-1-davidgow@google.com>
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On Thu, Apr 11, 2024 at 10:59 PM David Gow <davidgow@google.com> wrote:
>
> KUnit's try-catch infrastructure now uses vfork_done, which is always
> set to a valid completion when a kthread is created, but which is set to
> NULL once the thread terminates. This creates a race condition, where
> the kthread exits before we can wait on it.
>
> Keep a copy of vfork_done, which is taken before we wake_up_process()
> and so valid, and wait on that instead.
>
> Fixes: 4de2a8e4cca4 ("kunit: Handle test faults")
> Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
> Closes: https://lore.kernel.org/lkml/20240410102710.35911-1-naresh.kamboju@linaro.org/
> Tested-by: Linux Kernel Functional Testing <lkft@linaro.org>
> Acked-by: Mickaël Salaün <mic@digikod.net>
> Signed-off-by: David Gow <davidgow@google.com>

I noticed it with the Rust tests too, and indeed this fixed it:

Tested-by: Miguel Ojeda <ojeda@kernel.org>

Thanks!

Cheers,
Miguel