linux-kernel - Re: [PATCH] perf/x86/intel: Use rdmsrl

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Message-ID: <20140423153544.GD25378@pd.tnic>
Date:	Wed, 23 Apr 2014 17:35:44 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Stephane Eranian <eranian@...gle.com>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	Venkatesh Srinivas <venkateshs@...gle.com>,
	LKML <linux-kernel@...r.kernel.org>,
	"mingo@...e.hu" <mingo@...e.hu>,
	"ak@...ux.intel.com" <ak@...ux.intel.com>,
	"Yan, Zheng" <zheng.z.yan@...el.com>
Subject: Re: [PATCH] perf/x86/intel: Use rdmsrl_safe when initializing RAPL
 PMU.

On Wed, Apr 23, 2014 at 05:18:29PM +0200, Stephane Eranian wrote:
> On Wed, Apr 23, 2014 at 5:16 PM, Borislav Petkov <bp@...en8.de> wrote:
> > On Wed, Apr 23, 2014 at 05:14:33PM +0200, Stephane Eranian wrote:
> >> Wouldn't rdmsrl_safe() return 0 on success?
> >
> > Yes.
> >
> then the if() test is wrong:
> if (!rdmsrl_safe())
>    return -1;
> 
> Should be:
> if (rdmsrl_safe())
>   return -1;
> 
> Or am I missing something?

Yeah, that is wrong:

        if (!rdmsrl_safe(MSR_RAPL_POWER_UNIT, &msr_rapl_power_unit_bits))
                return -1;

On error we return -EIO, on success 0. Just remove the "!".


-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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