linux-kernel - Re: [PATCH] Cpufreq: Acquire read lock in the cpufreq_policy

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Message-ID: <2039668.8La2a0cgXT@vostro.rjw.lan>
Date:	Thu, 12 Sep 2013 00:56:03 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	tianyu.lan@...el.com
Cc:	viresh.kumar@...aro.org, srivatsa.bhat@...ux.vnet.ibm.com,
	cpufreq@...r.kernel.org, linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Cpufreq: Acquire read lock in the cpufreq_policy_restore() rather than write lock

On Wednesday, September 11, 2013 03:05:05 PM tianyu.lan@...el.com wrote:
> From: Lan Tianyu <tianyu.lan@...el.com>
> 
> In the cpufreq_policy_restore(), policy before system suspend is read from
> from percpu's cpufreq_cpu_data_fallback. It's read operation rather than
> write operation. So convert write lock to read lock
> 
> Signed-off-by: Lan Tianyu <tianyu.lan@...el.com>

Applied, thanks Tianyu!

> ---
>  drivers/cpufreq/cpufreq.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index 81ceea6..b762f9b 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -912,11 +912,11 @@ static struct cpufreq_policy *cpufreq_policy_restore(unsigned int cpu)
>  	struct cpufreq_policy *policy;
>  	unsigned long flags;
>  
> -	write_lock_irqsave(&cpufreq_driver_lock, flags);
> +	read_lock_irqsave(&cpufreq_driver_lock, flags);
>  
>  	policy = per_cpu(cpufreq_cpu_data_fallback, cpu);
>  
> -	write_unlock_irqrestore(&cpufreq_driver_lock, flags);
> +	read_unlock_irqrestore(&cpufreq_driver_lock, flags);
>  
>  	return policy;
>  }
> 
-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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