linux-kernel - Re: [PATCH v3 1/5] x86: initialize secondary CPU only if master CPU will wait for it

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Message-ID: <20140414091600.GA19771@gmail.com>
Date:	Mon, 14 Apr 2014 11:16:00 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	Igor Mammedov <imammedo@...hat.com>
Cc:	linux-kernel@...r.kernel.org, tglx@...utronix.de, mingo@...hat.com,
	hpa@...or.com, x86@...nel.org, bp@...e.de,
	paul.gortmaker@...driver.com, JBeulich@...e.com, prarit@...hat.com,
	drjones@...hat.com, toshi.kani@...com, riel@...hat.com,
	gong.chen@...ux.intel.com, andi@...stfloor.org, lenb@...nel.org,
	rjw@...ysocki.net, linux-acpi@...r.kernel.org
Subject: Re: [PATCH v3 1/5] x86: initialize secondary CPU only if master CPU
 will wait for it


* Igor Mammedov <imammedo@...hat.com> wrote:

>  	/*
> +	 * wait for ACK from master CPU before continuing
> +	 * with AP initialization
> +	 */
> +	cpumask_set_cpu(cpu, cpu_initialized_mask);
> +	while (!cpumask_test_cpu(cpu, cpu_callout_mask))
> +		cpu_relax();

> +	/*
> +	 * wait for ACK from master CPU before continuing
> +	 * with AP initialization
> +	 */
> +	cpumask_set_cpu(cpu, cpu_initialized_mask);
> +	while (!cpumask_test_cpu(cpu, cpu_callout_mask))
> +		cpu_relax();

That repetitive pattern could be stuck into a properly named helper 
inline function.

(Also, before the cpumask_set_cpu() we should probably do a WARN_ON() 
if the bit is already set.)

Thanks,

	Ingo
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