linux-kernel - Re: [tip:x86/tsc] x86: Check tsc available/disabled in the delayed init function

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Message-ID: <1292268162.2673.29.camel@work-vm>
Date:	Mon, 13 Dec 2010 11:22:42 -0800
From:	john stultz <johnstul@...ibm.com>
To:	linux-kernel@...r.kernel.org, mingo@...hat.com, hpa@...or.com,
	tglx@...utronix.de
Cc:	linux-tip-commits@...r.kernel.org
Subject: Re: [tip:x86/tsc] x86: Check tsc available/disabled in the delayed
 init function

On Mon, 2010-12-13 at 10:37 +0000, tip-bot for Thomas Gleixner wrote:
> Commit-ID:  a8760eca6cf60ed303ad494ef45901f63165d2c8
> Gitweb:     http://git.kernel.org/tip/a8760eca6cf60ed303ad494ef45901f63165d2c8
> Author:     Thomas Gleixner <tglx@...utronix.de>
> AuthorDate: Mon, 13 Dec 2010 11:28:02 +0100
> Committer:  Thomas Gleixner <tglx@...utronix.de>
> CommitDate: Mon, 13 Dec 2010 11:35:05 +0100
> 
> x86: Check tsc available/disabled in the delayed init function
> 
> The delayed TSC init function does not check whether the system has no
> TSC or TSC is disabled at the kernel command line, which results in a
> crash in the work queue based extended calibration due to division by
> zero because the basic calibration never happened.
> 
> Add the missing checks and do not touch TSC when not available or
> disabled.
> 
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> Cc: John Stultz <johnstul@...ibm.com>

Thanks for catching this!

Acked-by: John Stultz <johnstul@...ibm.com>


> ---
>  arch/x86/kernel/tsc.c |    3 +++
>  1 files changed, 3 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
> index dc1393e..356a0d4 100644
> --- a/arch/x86/kernel/tsc.c
> +++ b/arch/x86/kernel/tsc.c
> @@ -965,6 +965,9 @@ out:
> 
>  static int __init init_tsc_clocksource(void)
>  {
> +	if (!cpu_has_tsc || tsc_disabled > 0)
> +		return 0;
> +
>  	if (tsc_clocksource_reliable)
>  		clocksource_tsc.flags &= ~CLOCK_SOURCE_MUST_VERIFY;
>  	/* lower the rating if we already know its unstable: */


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