cpufreq: Mark policy->governor = NULL for inactive policies

Later commits would change the way policies are managed today. Policies
wouldn't be freed on cpu hotplug (currently they aren't freed on
suspend), and while the CPU is offline, the sysfs cpufreq files would
still be present.

Because we don't mark policy->governor as NULL, it still contains
pointer of the last used governor. And if the governor is removed, while
all the CPUs of a policy are hotplugged out, this pointer wouldn't be
valid anymore. And if we try to read the 'scaling_governor', etc.  from
sysfs, it will result in kernel OOPs.

To prevent this, mark policy->governor as NULL for all inactive policies
while the governor is removed from kernel.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 16275ba6428eb5cae94b1dee93d66dc7d432ad87..c08de5e985c778459e94606c01745121862db568 100644 (file)
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1083,7 +1083,6 @@ static struct cpufreq_policy *cpufreq_policy_restore(unsigned int cpu)
        if (likely(policy)) {
                /* Policy should be inactive here */
                WARN_ON(!policy_is_inactive(policy));
-               policy->governor = NULL;
        }
 
        return policy;
@@ -2145,8 +2144,10 @@ void cpufreq_unregister_governor(struct cpufreq_governor *governor)
        /* clear last_governor for all inactive policies */
        read_lock_irqsave(&cpufreq_driver_lock, flags);
        for_each_inactive_policy(policy) {
-               if (!strcmp(policy->last_governor, governor->name))
+               if (!strcmp(policy->last_governor, governor->name)) {
+                       policy->governor = NULL;
                        strcpy(policy->last_governor, "\0");
+               }
        }
        read_unlock_irqrestore(&cpufreq_driver_lock, flags);