linux-kernel - Re: [PATCH] x86/umwait: Fix error handling in umwait

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Date:   Sat, 10 Aug 2019 07:25:02 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Fenghua Yu <fenghua.yu@...el.com>
cc:     Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Valdis Kletnieks <valdis.kletnieks@...edu>,
        x86 <x86@...nel.org>, linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86/umwait: Fix error handling in umwait_init()

On Fri, 9 Aug 2019, Fenghua Yu wrote:
> +/*
> + * The CPU hotplug callback sets the control MSR to the original control
> + * value.
> + */
> +static int umwait_cpu_offline(unsigned int cpu)
> +{
> +	/*
> +	 * This code is protected by the CPU hotplug already and
> +	 * orig_umwait_control_cached is never changed after it caches
> +	 * the original control MSR value in umwait_init(). So there
> +	 * is no race condition here.
> +	 */
> +	wrmsr(MSR_IA32_UMWAIT_CONTROL, orig_umwait_control_cached, 0);

Even my brain compiler emits an error here.

Thanks,

	tglx