cpufreq: Keep a single path for adding managed CPUs

There are two cases when we may try to add CPUs we're already handling:
 - On boot, the first cpu has marked all policy->cpus managed and so we
   will find policy for all other policy->cpus later on.
 - When a managed cpu is hotplugged out and later brought back in.

Currently, separate paths and checks take care of the two.  While the
first one is detected by testing cpu against 'policy->cpus', the other
one is detected by testing cpu against 'policy->related_cpus'.

We can handle them both via a single path and there is no need to do
special checking for the first one.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Saravana Kannan <skannan@codeaurora.org>
[ rjw: Changelog, comments ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpufreq/cpufreq.c

@@ -992,6 +992,10 @@ static int cpufreq_add_policy_cpu(struct cpufreq_policy *policy,
 	int ret = 0;
 	unsigned long flags;
 
+	/* Has this CPU been taken care of already? */
+	if (cpumask_test_cpu(cpu, policy->cpus))
+		return 0;
+
 	if (has_target()) {
 		ret = __cpufreq_governor(policy, CPUFREQ_GOV_STOP);
 		if (ret) {
@@ -1147,16 +1151,10 @@ static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif)
 
 	pr_debug("adding CPU %u\n", cpu);
 
-	/* check whether a different CPU already registered this
-	 * CPU because it is in the same boat. */
-	policy = cpufreq_cpu_get_raw(cpu);
-	if (unlikely(policy))
-		return 0;
-
 	if (!down_read_trylock(&cpufreq_rwsem))
 		return 0;
 
-	/* Check if this cpu was hot-unplugged earlier and has siblings */
+	/* Check if this CPU already has a policy to manage it */
 	read_lock_irqsave(&cpufreq_driver_lock, flags);
 	for_each_policy(policy) {
 		if (cpumask_test_cpu(cpu, policy->related_cpus)) {