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

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Date:	Mon, 15 Apr 2013 11:54:47 +0530
From:	Amit Daniel Kachhap <amit.daniel@...sung.com>
To:	linux-pm@...r.kernel.org, "Rafael J. Wysocki" <rjw@...k.pl>
Cc:	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: [PATCH] cpufreq: exynos5440: Protect opp search calls with rcu lock

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)

 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;
 }
 
-- 
1.7.1

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