linux-kernel - [PATCH V5 1/6] cpufreq: Merge cpufreq_offline

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Message-Id: <4266bafe3c9baad4996352e3f7780344e854b002.1455191663.git.viresh.kumar@linaro.org>
Date:	Thu, 11 Feb 2016 17:31:11 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	Rafael Wysocki <rjw@...ysocki.net>, juri.lelli@....com
Cc:	linaro-kernel@...ts.linaro.org, linux-pm@...r.kernel.org,
	shilpa.bhat@...ux.vnet.ibm.com, linux-kernel@...r.kernel.org,
	Viresh Kumar <viresh.kumar@...aro.org>
Subject: [PATCH V5 1/6] cpufreq: Merge cpufreq_offline_prepare/finish routines

Governor sysfs attributes are still removed in
__cpufreq_governor(_EXIT), though, so had store() been used for them,
the deadlock described in the changelog of commit 1aee40ac9c86 would
have been possible.

Fortunately, we don't use store() (which still does get_online_cpus())
for those attributes now.  We use governor_store() for them and that
doesn't call get_online_cpus().

And so we don't need to split cpufreq-offline functionality into
DOWN_PREPARE and POST_DEAD hotplug notifiers anymore.

Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
[ rjw: Changelog ]
Tested-by: Juri Lelli <juri.lelli@....com>
Tested-by: Shilpasri G Bhat <shilpa.bhat@...ux.vnet.ibm.com>
---
 drivers/cpufreq/cpufreq.c | 36 ++++++++++--------------------------
 1 file changed, 10 insertions(+), 26 deletions(-)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 9c62bf35b9dc..863ac26c4ecf 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1361,9 +1361,10 @@ static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif)
 	return ret;
 }
 
-static void cpufreq_offline_prepare(unsigned int cpu)
+static void cpufreq_offline(unsigned int cpu)
 {
 	struct cpufreq_policy *policy;
+	int ret;
 
 	pr_debug("%s: unregistering CPU %u\n", __func__, cpu);
 
@@ -1374,7 +1375,7 @@ static void cpufreq_offline_prepare(unsigned int cpu)
 	}
 
 	if (has_target()) {
-		int ret = __cpufreq_governor(policy, CPUFREQ_GOV_STOP);
+		ret = __cpufreq_governor(policy, CPUFREQ_GOV_STOP);
 		if (ret)
 			pr_err("%s: Failed to stop governor\n", __func__);
 	}
@@ -1397,34 +1398,23 @@ static void cpufreq_offline_prepare(unsigned int cpu)
 	/* Start governor again for active policy */
 	if (!policy_is_inactive(policy)) {
 		if (has_target()) {
-			int ret = __cpufreq_governor(policy, CPUFREQ_GOV_START);
+			ret = __cpufreq_governor(policy, CPUFREQ_GOV_START);
 			if (!ret)
 				ret = __cpufreq_governor(policy, CPUFREQ_GOV_LIMITS);
 
 			if (ret)
 				pr_err("%s: Failed to start governor\n", __func__);
 		}
-	} else if (cpufreq_driver->stop_cpu) {
-		cpufreq_driver->stop_cpu(policy);
-	}
-}
 
-static void cpufreq_offline_finish(unsigned int cpu)
-{
-	struct cpufreq_policy *policy = per_cpu(cpufreq_cpu_data, cpu);
-
-	if (!policy) {
-		pr_debug("%s: No cpu_data found\n", __func__);
 		return;
 	}
 
-	/* Only proceed for inactive policies */
-	if (!policy_is_inactive(policy))
-		return;
+	if (cpufreq_driver->stop_cpu)
+		cpufreq_driver->stop_cpu(policy);
 
 	/* If cpu is last user of policy, free policy */
 	if (has_target()) {
-		int ret = __cpufreq_governor(policy, CPUFREQ_GOV_POLICY_EXIT);
+		ret = __cpufreq_governor(policy, CPUFREQ_GOV_POLICY_EXIT);
 		if (ret)
 			pr_err("%s: Failed to exit governor\n", __func__);
 	}
@@ -1453,10 +1443,8 @@ static void cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif)
 	if (!policy)
 		return;
 
-	if (cpu_online(cpu)) {
-		cpufreq_offline_prepare(cpu);
-		cpufreq_offline_finish(cpu);
-	}
+	if (cpu_online(cpu))
+		cpufreq_offline(cpu);
 
 	cpumask_clear_cpu(cpu, policy->real_cpus);
 	remove_cpu_dev_symlink(policy, cpu);
@@ -2304,11 +2292,7 @@ static int cpufreq_cpu_callback(struct notifier_block *nfb,
 		break;
 
 	case CPU_DOWN_PREPARE:
-		cpufreq_offline_prepare(cpu);
-		break;
-
-	case CPU_POST_DEAD:
-		cpufreq_offline_finish(cpu);
+		cpufreq_offline(cpu);
 		break;
 
 	case CPU_DOWN_FAILED:
-- 
2.7.1.370.gb2aa7f8