4.9-stable review patch. If anyone has any objections, please let me know.
------------------ From: Viresh Kumar <[email protected]> commit 289d72afddf83440117c35d864bf0c6309c1d011 upstream. 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. Fixes: 02373d7c69b4 ("thermal: cpu_cooling: fix lockdep problems in cpu_cooling") Signed-off-by: Viresh Kumar <[email protected]> Reviewed-by: Lukasz Luba <[email protected]> Tested-by: Lukasz Luba <[email protected]> Signed-off-by: Eduardo Valentin <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- drivers/thermal/cpu_cooling.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/drivers/thermal/cpu_cooling.c +++ b/drivers/thermal/cpu_cooling.c @@ -191,8 +191,10 @@ unsigned long cpufreq_cooling_get_level( 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);
