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[PATCH V3 01/17] thermal: cpu_cooling: Avoid accessing potentially freed structures

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After the lock is dropped, it is possible that the cpufreq_dev gets
freed before we call get_level() and that can cause kernel to crash.

Drop the lock after we are done using the structure.

Cc: 4.2+ <stable@vger.kernel.org> # 4.2+
Fixes: 02373d7c69b4 ("thermal: cpu_cooling: fix lockdep problems in cpu_cooling")
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 drivers/thermal/cpu_cooling.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
index 69d0f430b2d1..be29489dd247 100644
--- a/drivers/thermal/cpu_cooling.c
+++ b/drivers/thermal/cpu_cooling.c
@@ -153,8 +153,10 @@ unsigned long cpufreq_cooling_get_level(unsigned int cpu, unsigned int freq)
 	mutex_lock(&cooling_list_lock);
 	list_for_each_entry(cpufreq_dev, &cpufreq_dev_list, node) {
 		if (cpumask_test_cpu(cpu, &cpufreq_dev->allowed_cpus)) {
+			unsigned long level = get_level(cpufreq_dev, freq);
+
 			mutex_unlock(&cooling_list_lock);
-			return get_level(cpufreq_dev, freq);
+			return level;
 		}
 	}
 	mutex_unlock(&cooling_list_lock);
-- 
2.12.0.432.g71c3a4f4ba37

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[PATCH V3 00/17] thermal: cpu_cooling: improve interaction with cpufreq core Viresh Kumar <viresh.kumar@linaro.org> - 2017-04-19 07:40 +0200
  [PATCH V3 01/17] thermal: cpu_cooling: Avoid accessing potentially freed structures Viresh Kumar <viresh.kumar@linaro.org> - 2017-04-19 07:40 +0200
  [PATCH V3 11/17] thermal: cpu_cooling: get rid of 'allowed_cpus' Viresh Kumar <viresh.kumar@linaro.org> - 2017-04-19 07:40 +0200
    Re: [PATCH V3 11/17] thermal: cpu_cooling: get rid of 'allowed_cpus' Lukasz Luba <lukasz.luba@arm.com> - 2017-04-24 19:00 +0200
  [PATCH V3 05/17] thermal: cpu_cooling: remove cpufreq_cooling_get_level() Viresh Kumar <viresh.kumar@linaro.org> - 2017-04-19 07:40 +0200
  [PATCH V3 15/17] thermal: cpu_cooling: don't store cpu_dev in cpufreq_cdev Viresh Kumar <viresh.kumar@linaro.org> - 2017-04-19 07:40 +0200

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