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 --- drivers/cpufreq/cpufreq.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 5e87679ec6d1..bd8a47b5054e 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -1095,7 +1095,6 @@ 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; @@ -2157,8 +2156,10 @@ 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, tpolicy) { - 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);