Date: Fri, 22 Jun 2012 18:36:43 +0200
From: Robert Richter <robert.richter@amd.com>
To: Peter Zijlstra <peterz@infradead.org>
CC: Ingo Molnar <mingo@kernel.org>, Stephane Eranian <eranian@google.com>,
        LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 4/4] perf, x86: Improve debug output in check_hw_exists()
Message-ID: <20120622163643.GK24632@erda.amd.com>
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On 22.06.12 17:53:47, Peter Zijlstra wrote:
> My gcc wants me to add the below to avoid used uninitialized warns:
> 
> ---
> --- a/arch/x86/kernel/cpu/perf_event.c
> +++ b/arch/x86/kernel/cpu/perf_event.c
> @@ -211,8 +211,9 @@ static bool check_hw_exists(void)
>  	 * that don't trap on the MSR access and always return 0s.
>  	 */
>  	val = 0xabcdUL;
> -	ret = wrmsrl_safe(x86_pmu_event_addr(0), val);
> -	ret |= rdmsrl_safe(x86_pmu_event_addr(0), &val_new);
> +	reg = x86_pmu_event_addr(0);
> +	ret = wrmsrl_safe(reg, val);
> +	ret |= rdmsrl_safe(reg, &val_new);

Yes, this is correct. It fixes also correct reporting of reg if it
fails here.

I wonder why my gcc this didn't report, its 4.4.5.

Thanks,

-Robert

-- 
Advanced Micro Devices, Inc.
Operating System Research Center

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