linux-kernel - [PATCH 3/4] cpufreq: dt: Try freeing static OPPs only if we have added them

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Date:   Thu,  4 Oct 2018 09:46:22 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:     Viresh Kumar <viresh.kumar@...aro.org>, linux-pm@...r.kernel.org,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Stephen Boyd <sboyd@...nel.org>, Nishanth Menon <nm@...com>,
        niklas.cassel@...aro.org, d-gerlach@...com,
        linux-kernel@...r.kernel.org
Subject: [PATCH 3/4] cpufreq: dt: Try freeing static OPPs only if we have added them

We can not call dev_pm_opp_of_cpumask_remove_table() freely anymore
since the latest OPP core updates as that uses reference counting to
free resources. There are cases where no static OPPs are added (using
DT) for a platform and trying to remove the OPP table may end up
decrementing refcount which is already zero and hence generating
warnings.

Lets track if we were able to add static OPPs or not and then only
remove the table based on that. Some reshuffling of code is also done to
do that.

Reported-by: Niklas Cassel <niklas.cassel@...aro.org>
Tested-by: Niklas Cassel <niklas.cassel@...aro.org>
Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
---
 drivers/cpufreq/cpufreq-dt.c | 34 +++++++++++++++++++---------------
 1 file changed, 19 insertions(+), 15 deletions(-)

diff --git a/drivers/cpufreq/cpufreq-dt.c b/drivers/cpufreq/cpufreq-dt.c
index 0a9ebf00be46..e58bfcb1169e 100644
--- a/drivers/cpufreq/cpufreq-dt.c
+++ b/drivers/cpufreq/cpufreq-dt.c
@@ -32,6 +32,7 @@ struct private_data {
 	struct device *cpu_dev;
 	struct thermal_cooling_device *cdev;
 	const char *reg_name;
+	bool have_static_opps;
 };
 
 static struct freq_attr *cpufreq_dt_attr[] = {
@@ -204,6 +205,15 @@ static int cpufreq_init(struct cpufreq_policy *policy)
 		}
 	}
 
+	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+	if (!priv) {
+		ret = -ENOMEM;
+		goto out_put_regulator;
+	}
+
+	priv->reg_name = name;
+	priv->opp_table = opp_table;
+
 	/*
 	 * Initialize OPP tables for all policy->cpus. They will be shared by
 	 * all CPUs which have marked their CPUs shared with OPP bindings.
@@ -214,7 +224,8 @@ static int cpufreq_init(struct cpufreq_policy *policy)
 	 *
 	 * OPPs might be populated at runtime, don't check for error here
 	 */
-	dev_pm_opp_of_cpumask_add_table(policy->cpus);
+	if (!dev_pm_opp_of_cpumask_add_table(policy->cpus))
+		priv->have_static_opps = true;
 
 	/*
 	 * But we need OPP table to function so if it is not there let's
@@ -240,19 +251,10 @@ static int cpufreq_init(struct cpufreq_policy *policy)
 				__func__, ret);
 	}
 
-	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
-	if (!priv) {
-		ret = -ENOMEM;
-		goto out_free_opp;
-	}
-
-	priv->reg_name = name;
-	priv->opp_table = opp_table;
-
 	ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table);
 	if (ret) {
 		dev_err(cpu_dev, "failed to init cpufreq table: %d\n", ret);
-		goto out_free_priv;
+		goto out_free_opp;
 	}
 
 	priv->cpu_dev = cpu_dev;
@@ -282,10 +284,11 @@ static int cpufreq_init(struct cpufreq_policy *policy)
 
 out_free_cpufreq_table:
 	dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table);
-out_free_priv:
-	kfree(priv);
 out_free_opp:
-	dev_pm_opp_of_cpumask_remove_table(policy->cpus);
+	if (priv->have_static_opps)
+		dev_pm_opp_of_cpumask_remove_table(policy->cpus);
+	kfree(priv);
+out_put_regulator:
 	if (name)
 		dev_pm_opp_put_regulators(opp_table);
 out_put_clk:
@@ -300,7 +303,8 @@ static int cpufreq_exit(struct cpufreq_policy *policy)
 
 	cpufreq_cooling_unregister(priv->cdev);
 	dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table);
-	dev_pm_opp_of_cpumask_remove_table(policy->related_cpus);
+	if (priv->have_static_opps)
+		dev_pm_opp_of_cpumask_remove_table(policy->related_cpus);
 	if (priv->reg_name)
 		dev_pm_opp_put_regulators(priv->opp_table);
 
-- 
2.18.0.rc1.242.g61856ae69a2c