linux-kernel - Re: [PATCH 1/2] posix-cpu-timers: avoid do_sys_times() races with __exit

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Message-ID: <20090612134626.GA3784@redhat.com>
Date:	Fri, 12 Jun 2009 15:46:26 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Stanislaw Gruszka <sgruszka@...hat.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Ingo Molnar <mingo@...e.hu>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 1/2] posix-cpu-timers: avoid do_sys_times() races with
	__exit_signal()

On 06/12, Stanislaw Gruszka wrote:
>
> Protect thread_group_cputime() call by siglock, to avoid possible (but
> to be honest - very improbable) double times accounting of exiting task.
> This is revert of commit 2b5fe6de58276d0b5a7c884d5dbfc300ca47db78
> "thread_group_cputime: move a couple of callsites outside of ->siglock",
> but implementation of thread_group_cputime() was different then.

Yes, at that time thread_group_cputime() was reading per-cpu data, and
->siglock was unneeded.

I think the patch is correct.

Oleg.

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