diff options
| -rw-r--r-- | drivers/cpufreq/cpufreq.c | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 8ae655c364f4..5ff57b0c2f47 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -207,6 +207,23 @@ struct cpufreq_policy *cpufreq_cpu_get_raw(unsigned int cpu) return per_cpu(cpufreq_cpu_data, cpu); } +/** + * cpufreq_cpu_get: returns policy for a cpu and marks it busy. + * + * @cpu: cpu to find policy for. + * + * This returns policy for 'cpu', returns NULL if it doesn't exist. + * It also increments the kobject reference count to mark it busy and so would + * require a corresponding call to cpufreq_cpu_put() to decrement it back. + * If corresponding call cpufreq_cpu_put() isn't made, the policy wouldn't be + * freed as that depends on the kobj count. + * + * It also takes a read-lock of 'cpufreq_rwsem' and doesn't put it back if a + * valid policy is found. This is done to make sure the driver doesn't get + * unregistered while the policy is being used. + * + * Return: A valid policy on success, otherwise NULL on failure. + */ struct cpufreq_policy *cpufreq_cpu_get(unsigned int cpu) { struct cpufreq_policy *policy = NULL; @@ -237,6 +254,16 @@ struct cpufreq_policy *cpufreq_cpu_get(unsigned int cpu) } EXPORT_SYMBOL_GPL(cpufreq_cpu_get); +/** + * cpufreq_cpu_put: Decrements the usage count of a policy + * + * @policy: policy earlier returned by cpufreq_cpu_get(). + * + * This decrements the kobject reference count incremented earlier by calling + * cpufreq_cpu_get(). + * + * It also drops the read-lock of 'cpufreq_rwsem' taken at cpufreq_cpu_get(). + */ void cpufreq_cpu_put(struct cpufreq_policy *policy) { kobject_put(&policy->kobj); |