Power management fixes for v4.7-rc6

- Fix a recent intel_pstate regression that caused the number of
    wakeups to increase significantly on an idle system in some cases
    due to excessive synchronize_sched() invocations (Rafael Wysocki).
 
  - Fix unnecessary invocations of WARN_ON() in the cpufreq core
    after cpufreq has been suspended introduced during the 4.6 cycla
    (Rafael Wysocki).
 
  - Fix an error code path in the cpufreq-dt-platdev driver that
    forgets to drop a reference to a DT node (Masahiro Yamada).
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Merge tag 'pm-4.7-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

Pull power management fixes from Rafael Wysocki:
 "Three cpufreq fixes, one in the core (stable-candidate) and two in
  drivers (intel_pstate and cpufreq-dt).

  Specifics:

   - Fix a recent intel_pstate regression that caused the number of
     wakeups to increase significantly on an idle system in some cases
     due to excessive synchronize_sched() invocations (Rafael Wysocki).

   - Fix unnecessary invocations of WARN_ON() in the cpufreq core after
     cpufreq has been suspended introduced during the 4.6 cycla (Rafael
     Wysocki).

   - Fix an error code path in the cpufreq-dt-platdev driver that
     forgets to drop a reference to a DT node (Masahiro Yamada)"

* tag 'pm-4.7-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  cpufreq: Avoid false-positive WARN_ON()s in cpufreq_update_policy()
  cpufreq: dt: call of_node_put() before error out
  intel_pstate: Do not clear utilization update hooks on policy changes

drivers/cpufreq/cpufreq-dt-platdev.c

@@ -79,15 +79,16 @@ static const struct of_device_id machines[] __initconst = {
 static int __init cpufreq_dt_platdev_init(void)
 {
 	struct device_node *np = of_find_node_by_path("/");
+	const struct of_device_id *match;
 
 	if (!np)
 		return -ENODEV;
 
-	if (!of_match_node(machines, np))
+	match = of_match_node(machines, np);
+	of_node_put(np);
+	if (!match)
 		return -ENODEV;
 
-	of_node_put(of_root);
-
 	return PTR_ERR_OR_ZERO(platform_device_register_simple("cpufreq-dt", -1,
 							       NULL, 0));
 }

drivers/cpufreq/cpufreq.c

@@ -2261,6 +2261,10 @@ int cpufreq_update_policy(unsigned int cpu)
 	 * -> ask driver for current freq and notify governors about a change
 	 */
 	if (cpufreq_driver->get && !cpufreq_driver->setpolicy) {
+		if (cpufreq_suspended) {
+			ret = -EAGAIN;
+			goto unlock;
+		}
 		new_policy.cur = cpufreq_update_current_freq(policy);
 		if (WARN_ON(!new_policy.cur)) {
 			ret = -EIO;

drivers/cpufreq/intel_pstate.c

@@ -1400,6 +1400,9 @@ static void intel_pstate_set_update_util_hook(unsigned int cpu_num)
 {
 	struct cpudata *cpu = all_cpu_data[cpu_num];
 
+	if (cpu->update_util_set)
+		return;
+
 	/* Prevent intel_pstate_update_util() from using stale data. */
 	cpu->sample.time = 0;
 	cpufreq_add_update_util_hook(cpu_num, &cpu->update_util,
@@ -1440,8 +1443,6 @@ static int intel_pstate_set_policy(struct cpufreq_policy *policy)
 	if (!policy->cpuinfo.max_freq)
 		return -ENODEV;
 
-	intel_pstate_clear_update_util_hook(policy->cpu);
-
 	pr_debug("set_policy cpuinfo.max %u policy->max %u\n",
 		 policy->cpuinfo.max_freq, policy->max);