linux-kernel - Re: [PATCH] perf: Fix sys_perf_event

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Message-ID: <Y3YiCkjsa3NLIpq6@zn.tnic>
Date:   Thu, 17 Nov 2022 12:59:06 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Ravi Bangoria <ravi.bangoria@....com>
Cc:     Peter Zijlstra <peterz@...radead.org>, nslusarek@....net,
        Linus Torvalds <torvalds@...ux-foundation.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] perf: Fix sys_perf_event_open() race against self

On Thu, Nov 17, 2022 at 04:29:31PM +0530, Ravi Bangoria wrote:
> I do agree that more tests are always better. Though, this simple program
> was to test a _specific race condition_ which no longer exists in kernel.
> So even if we add it, what would it test?

It would make sure that race doesn't happen again. Or are you saying it
will never ever happen so no need? Because we never ever rewrite the
kernel?

Lemme save us some time: this test is dirt cheap. It is good to have so
that multithreaded sys_perf_event_open() is exercised. And once it is
there, someone else might have a look at it and improve it more or reuse
it for another test.

And there are no downsides.

If you're still not convinced, lemme know and I'll turn it into a proper
patch and submit it.

Thx.

-- 
Regards/Gruss,
    Boris.

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