linux-kernel - Re: [PATCH 1/2] CPUFREQ: Remove unneeded dbs_mutexes from ondemand and conservative governors

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Date:	Tue, 30 Jun 2009 08:33:39 +0200
From:	Pavel Machek <pavel@....cz>
To:	Thomas Renninger <trenn@...e.de>
Cc:	kernel@...ble.org, cpufreq@...r.kernel.org,
	linux-kernel@...r.kernel.org, mingo@...e.hu, rjw@...k.pl,
	hidave.darkstar@...il.com, penberg@...helsinki.fi,
	kernel-testers@...r.kernel.org, davej@...hat.com,
	mathieu.desnoyers@...ymtl.ca,
	Venkatesh Pallipadi <venkatesh.pallipadi@...el.com>
Subject: Re: [PATCH 1/2] CPUFREQ: Remove unneeded dbs_mutexes from ondemand
	and conservative governors

On Thu 2009-06-25 16:01:24, Thomas Renninger wrote:
> Comment from Venkatesh:
> ...
> This mutex is just serializing the changes to those variables. I could't
> think of any functionality issues of not having the lock as such.
> 
> -> rip it out.
> 
> CC: Venkatesh Pallipadi <venkatesh.pallipadi@...el.com>
> Signed-off-by: Thomas Renninger <trenn@...e.de>

>  static struct dbs_tuners {
> @@ -236,10 +222,7 @@ static ssize_t store_sampling_down_factor(struct cpufreq_policy *unused,
>  	if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
>  		return -EINVAL;
>  
> -	mutex_lock(&dbs_mutex);
>  	dbs_tuners_ins.sampling_down_factor = input;
> -	mutex_unlock(&dbs_mutex);
> -

You'd need to make s_down_factor atomic_t for this to work....
								Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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