linux-kernel - Re: [PATCH] selftests/seccomp: use 90s as timeout

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Message-ID: <202006011249.3E72ABDDE3@keescook>
Date:   Mon, 1 Jun 2020 12:49:42 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Thadeu Lima de Souza Cascardo <cascardo@...onical.com>
Cc:     linux-kselftest@...r.kernel.org, Shuah Khan <shuah@...nel.org>,
        linux-kernel@...r.kernel.org,
        Andy Lutomirski <luto@...capital.net>,
        Will Drewry <wad@...omium.org>
Subject: Re: [PATCH] selftests/seccomp: use 90s as timeout

On Mon, Jun 01, 2020 at 09:32:02AM -0300, Thadeu Lima de Souza Cascardo wrote:
> As seccomp_benchmark tries to calibrate how many samples will take more
> than 5 seconds to execute, it may end up picking up a number of samples
> that take 10 (but up to 12) seconds. As the calibration will take double
> that time, it takes around 20 seconds. Then, it executes the whole thing
> again, and then once more, with some added overhead. So, the thing might
> take more than 40 seconds, which is too close to the 45s timeout.
> 
> That is very dependent on the system where it's executed, so may not be
> observed always, but it has been observed on x86 VMs. Using a 90s timeout
> seems safe enough.
> 
> Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@...onical.com>

Excellent point! Thanks, I've applied this (well, actually, your v2)
to for-next/seccomp.

-- 
Kees Cook