We can't take a big lock around __cpufreq_governor() as this causes recursive locking for some cases. But calls to this routine must be serialized for every policy.
Lets introduce another variable which would guarantee serialization here.
Signed-off-by: Viresh Kumar viresh.kumar@linaro.org --- drivers/cpufreq/cpufreq.c | 7 ++++++- include/linux/cpufreq.h | 1 + 2 files changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index f320a20..4d5723db 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -1692,13 +1692,15 @@ static int __cpufreq_governor(struct cpufreq_policy *policy, policy->cpu, event);
mutex_lock(&cpufreq_governor_lock); - if ((policy->governor_enabled && (event == CPUFREQ_GOV_START)) || + if (policy->governor_busy || + (policy->governor_enabled && (event == CPUFREQ_GOV_START)) || (!policy->governor_enabled && ((event == CPUFREQ_GOV_LIMITS) || (event == CPUFREQ_GOV_STOP)))) { mutex_unlock(&cpufreq_governor_lock); return -EBUSY; }
+ policy->governor_busy = true; if (event == CPUFREQ_GOV_STOP) policy->governor_enabled = false; else if (event == CPUFREQ_GOV_START) @@ -1727,6 +1729,9 @@ static int __cpufreq_governor(struct cpufreq_policy *policy, ((event == CPUFREQ_GOV_POLICY_EXIT) && !ret)) module_put(policy->governor->owner);
+ mutex_lock(&cpufreq_governor_lock); + policy->governor_busy = false; + mutex_unlock(&cpufreq_governor_lock); return ret; }
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h index d568f39..cca885d 100644 --- a/include/linux/cpufreq.h +++ b/include/linux/cpufreq.h @@ -76,6 +76,7 @@ struct cpufreq_policy { struct cpufreq_governor *governor; /* see below */ void *governor_data; bool governor_enabled; /* governor start/stop flag */ + bool governor_busy;
struct work_struct update; /* if update_policy() needs to be * called, but you're in IRQ context */