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-rw-r--r--drivers/cpufreq/cpufreq.c24
-rw-r--r--include/linux/cpufreq.h1
2 files changed, 25 insertions, 0 deletions
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index f8c2860..43cf608 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -49,6 +49,7 @@ static DEFINE_PER_CPU(struct cpufreq_policy *, cpufreq_cpu_data);
static DEFINE_PER_CPU(char[CPUFREQ_NAME_LEN], cpufreq_cpu_governor);
#endif
static DEFINE_RWLOCK(cpufreq_driver_lock);
+static DEFINE_MUTEX(cpufreq_governor_lock);
/*
* cpu_policy_rwsem is a per CPU reader-writer semaphore designed to cure
@@ -1635,6 +1636,21 @@ static int __cpufreq_governor(struct cpufreq_policy *policy,
pr_debug("__cpufreq_governor for CPU %u, event %u\n",
policy->cpu, event);
+
+ mutex_lock(&cpufreq_governor_lock);
+ if ((!policy->governor_enabled && (event == CPUFREQ_GOV_STOP)) ||
+ (policy->governor_enabled && (event == CPUFREQ_GOV_START))) {
+ mutex_unlock(&cpufreq_governor_lock);
+ return -EBUSY;
+ }
+
+ if (event == CPUFREQ_GOV_STOP)
+ policy->governor_enabled = false;
+ else if (event == CPUFREQ_GOV_START)
+ policy->governor_enabled = true;
+
+ mutex_unlock(&cpufreq_governor_lock);
+
ret = policy->governor->governor(policy, event);
if (!ret) {
@@ -1642,6 +1658,14 @@ static int __cpufreq_governor(struct cpufreq_policy *policy,
policy->governor->initialized++;
else if (event == CPUFREQ_GOV_POLICY_EXIT)
policy->governor->initialized--;
+ } else {
+ /* Restore original values */
+ mutex_lock(&cpufreq_governor_lock);
+ if (event == CPUFREQ_GOV_STOP)
+ policy->governor_enabled = true;
+ else if (event == CPUFREQ_GOV_START)
+ policy->governor_enabled = false;
+ mutex_unlock(&cpufreq_governor_lock);
}
/* we keep one module reference alive for
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index d939056..125719d 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -111,6 +111,7 @@ struct cpufreq_policy {
unsigned int policy; /* see above */
struct cpufreq_governor *governor; /* see below */
void *governor_data;
+ bool governor_enabled; /* governor start/stop flag */
struct work_struct update; /* if update_policy() needs to be
* called, but you're in IRQ context */