linux-kernel - [PATCH V3 2/9] PM / OPP: Don't use OPP structure outside of rcu protected section

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Message-Id: <57dffa3dc126fed6690a79a8ca1f192ef1c2a79e.1477463128.git.viresh.kumar@linaro.org>
Date:   Wed, 26 Oct 2016 12:02:57 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Rafael Wysocki <rjw@...ysocki.net>, nm@...com,
        sboyd@...eaurora.org, Viresh Kumar <vireshk@...nel.org>
Cc:     linaro-kernel@...ts.linaro.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Vincent Guittot <vincent.guittot@...aro.org>, robh@...nel.org,
        d-gerlach@...com, broonie@...nel.org,
        Viresh Kumar <viresh.kumar@...aro.org>
Subject: [PATCH V3 2/9] PM / OPP: Don't use OPP structure outside of rcu protected section

The OPP structure must not be used out of the rcu protected section.
Cache the values to be used in separate variables instead.

Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
Tested-by: Dave Gerlach <d-gerlach@...com>
---
 drivers/base/power/opp/core.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/base/power/opp/core.c b/drivers/base/power/opp/core.c
index 4c7c6da7a989..056527a3fb4e 100644
--- a/drivers/base/power/opp/core.c
+++ b/drivers/base/power/opp/core.c
@@ -584,6 +584,7 @@ int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq)
 	struct clk *clk;
 	unsigned long freq, old_freq;
 	unsigned long u_volt, u_volt_min, u_volt_max;
+	unsigned long old_u_volt, old_u_volt_min, old_u_volt_max;
 	int ret;
 
 	if (unlikely(!target_freq)) {
@@ -633,6 +634,14 @@ int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq)
 		return ret;
 	}
 
+	if (IS_ERR(old_opp)) {
+		old_u_volt = 0;
+	} else {
+		old_u_volt = old_opp->u_volt;
+		old_u_volt_min = old_opp->u_volt_min;
+		old_u_volt_max = old_opp->u_volt_max;
+	}
+
 	u_volt = opp->u_volt;
 	u_volt_min = opp->u_volt_min;
 	u_volt_max = opp->u_volt_max;
@@ -677,9 +686,10 @@ int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq)
 			__func__, old_freq);
 restore_voltage:
 	/* This shouldn't harm even if the voltages weren't updated earlier */
-	if (!IS_ERR(old_opp))
-		_set_opp_voltage(dev, reg, old_opp->u_volt,
-				 old_opp->u_volt_min, old_opp->u_volt_max);
+	if (old_u_volt) {
+		_set_opp_voltage(dev, reg, old_u_volt, old_u_volt_min,
+				 old_u_volt_max);
+	}
 
 	return ret;
 }
-- 
2.7.1.410.g6faf27b