linux-kernel - Re: [PATCH] cpufreq: exynos5440: Protect opp search calls with rcu lock

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Date:	Mon, 22 Apr 2013 01:32:17 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Amit Daniel Kachhap <amit.daniel@...sung.com>
Cc:	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-samsung-soc@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	Kukjin Kim <kgene.kim@...sung.com>, cpufreq@...r.kernel.org,
	Nishanth Menon <nm@...com>
Subject: Re: [PATCH] cpufreq: exynos5440: Protect opp search calls with rcu lock

On Monday, April 15, 2013 11:54:47 AM Amit Daniel Kachhap wrote:
> As per the OPP library documentation(Documentation/power/opp.txt) all
> opp find/get calls should be protected by rcu locks.
> 
> Signed-off-by: Amit Daniel Kachhap <amit.daniel@...sung.com>
> ---
> 
> This patch is created against linux-next tree and is suggested by
> Nishanth Menon. (https://lkml.org/lkml/2013/4/12/119)

Applied.

Thanks,
Rafael


>  drivers/cpufreq/exynos5440-cpufreq.c |    3 +++
>  1 files changed, 3 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/cpufreq/exynos5440-cpufreq.c b/drivers/cpufreq/exynos5440-cpufreq.c
> index ead7ed4..0c74018 100644
> --- a/drivers/cpufreq/exynos5440-cpufreq.c
> +++ b/drivers/cpufreq/exynos5440-cpufreq.c
> @@ -120,11 +120,13 @@ static int init_div_table(void)
>  	int i = 0;
>  	struct opp *opp;
>  
> +	rcu_read_lock();
>  	for (i = 0; freq_tbl[i].frequency != CPUFREQ_TABLE_END; i++) {
>  
>  		opp = opp_find_freq_exact(dvfs_info->dev,
>  					freq_tbl[i].frequency * 1000, true);
>  		if (IS_ERR(opp)) {
> +			rcu_read_unlock();
>  			dev_err(dvfs_info->dev,
>  				"failed to find valid OPP for %u KHZ\n",
>  				freq_tbl[i].frequency);
> @@ -159,6 +161,7 @@ static int init_div_table(void)
>  		__raw_writel(tmp, dvfs_info->base + XMU_PMU_P0_7 + 4 * i);
>  	}
>  
> +	rcu_read_unlock();
>  	return 0;
>  }
>  
> 
-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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