cpufreq: Add cpufreq_cpu_acquire() and cpufreq_cpu_release()

}

EXPORT_SYMBOL_GPL(cpufreq_cpu_put);

/**

 * cpufreq_cpu_release - Unlock a policy and decrement its usage counter.

 * @policy: cpufreq policy returned by cpufreq_cpu_acquire().

 */

static void cpufreq_cpu_release(struct cpufreq_policy *policy)

{

	if (WARN_ON(!policy))

		return;

	lockdep_assert_held(&policy->rwsem);

	up_write(&policy->rwsem);

	cpufreq_cpu_put(policy);

}

/**

 * cpufreq_cpu_acquire - Find policy for a CPU, mark it as busy and lock it.

 * @cpu: CPU to find the policy for.

 *

 * Call cpufreq_cpu_get() to get a reference on the cpufreq policy for @cpu and

 * if the policy returned by it is not NULL, acquire its rwsem for writing.

 * Return the policy if it is active or release it and return NULL otherwise.

 *

 * The policy returned by this function has to be released with the help of

 * cpufreq_cpu_release() in order to release its rwsem and balance its usage

 * counter properly.

 */

static struct cpufreq_policy *cpufreq_cpu_acquire(unsigned int cpu)

{

	struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);

	if (!policy)

		return NULL;

	down_write(&policy->rwsem);

	if (policy_is_inactive(policy)) {

		cpufreq_cpu_release(policy);

		return NULL;

	}

	return policy;

}

/*********************************************************************

 *            EXTERNALLY AFFECTING FREQUENCY CHANGES                 *

 *********************************************************************/

 */

void cpufreq_update_policy(unsigned int cpu)

{

	struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);

	struct cpufreq_policy *policy = cpufreq_cpu_acquire(cpu);

	struct cpufreq_policy new_policy;

	if (!policy)

		return;

	down_write(&policy->rwsem);

	if (policy_is_inactive(policy))

		goto unlock;

	/*

	 * BIOS might change freq behind our back

	 * -> ask driver for current freq and notify governors about a change

	cpufreq_set_policy(policy, &new_policy);

unlock:

	up_write(&policy->rwsem);

	cpufreq_cpu_put(policy);

	cpufreq_cpu_release(policy);

}

EXPORT_SYMBOL(cpufreq_update_policy);