commit 3de9bdeb28638e164d1f0eb38dd68e3f5d2ac95c
author Viresh Kumar <viresh.kumar@linaro.org> Tue Aug 06 22:53:13 2013 +0530
committer Rafael J. Wysocki <rafael.j.wysocki@intel.com> Sat Aug 10 03:24:48 2013 +0200
tree efe5c314af79f28840a2a31eb2e2ca992c0258ae
parent adc97d6a735dbb1e94cb4f1bf0b55f258b349941

cpufreq: improve error checking on return values of __cpufreq_governor()

The __cpufreq_governor() function can fail in rare cases especially
if there are bugs in cpufreq drivers.  Thus we must stop processing
as soon as this routine fails, otherwise it may result in undefined
behavior.

This patch adds error checking code whenever this routine is called
from any place.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpufreq/cpufreq.c

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index c9bbfee..37a6874 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -874,8 +874,13 @@
 	int ret = 0, has_target = !!cpufreq_driver->target;
 	unsigned long flags;
 
-	if (has_target)
-		__cpufreq_governor(policy, CPUFREQ_GOV_STOP);
+	if (has_target) {
+		ret = __cpufreq_governor(policy, CPUFREQ_GOV_STOP);
+		if (ret) {
+			pr_err("%s: Failed to stop governor\n", __func__);
+			return ret;
+		}
+	}
 
 	lock_policy_rwsem_write(policy->cpu);
 
@@ -889,8 +894,11 @@
 	unlock_policy_rwsem_write(policy->cpu);
 
 	if (has_target) {
-		__cpufreq_governor(policy, CPUFREQ_GOV_START);
-		__cpufreq_governor(policy, CPUFREQ_GOV_LIMITS);
+		if ((ret = __cpufreq_governor(policy, CPUFREQ_GOV_START)) ||
+			(ret = __cpufreq_governor(policy, CPUFREQ_GOV_LIMITS))) {
+			pr_err("%s: Failed to start governor\n", __func__);
+			return ret;
+		}
 	}
 
 	/* Don't touch sysfs links during light-weight init */
@@ -1172,7 +1180,7 @@
 				struct subsys_interface *sif, bool frozen)
 {
 	unsigned int cpu = dev->id, cpus;
-	int new_cpu;
+	int new_cpu, ret;
 	unsigned long flags;
 	struct cpufreq_policy *policy;
 	struct kobject *kobj;
@@ -1196,8 +1204,13 @@
 		return -EINVAL;
 	}
 
-	if (cpufreq_driver->target)
-		__cpufreq_governor(policy, CPUFREQ_GOV_STOP);
+	if (cpufreq_driver->target) {
+		ret = __cpufreq_governor(policy, CPUFREQ_GOV_STOP);
+		if (ret) {
+			pr_err("%s: Failed to stop governor\n", __func__);
+			return ret;
+		}
+	}
 
 #ifdef CONFIG_HOTPLUG_CPU
 	if (!cpufreq_driver->setpolicy)
@@ -1231,8 +1244,15 @@
 
 	/* If cpu is last user of policy, free policy */
 	if (cpus == 1) {
-		if (cpufreq_driver->target)
-			__cpufreq_governor(policy, CPUFREQ_GOV_POLICY_EXIT);
+		if (cpufreq_driver->target) {
+			ret = __cpufreq_governor(policy,
+					CPUFREQ_GOV_POLICY_EXIT);
+			if (ret) {
+				pr_err("%s: Failed to exit governor\n",
+						__func__);
+				return ret;
+			}
+	}
 
 		if (!frozen) {
 			lock_policy_rwsem_read(cpu);
@@ -1263,8 +1283,12 @@
 			cpufreq_policy_free(policy);
 	} else {
 		if (cpufreq_driver->target) {
-			__cpufreq_governor(policy, CPUFREQ_GOV_START);
-			__cpufreq_governor(policy, CPUFREQ_GOV_LIMITS);
+			if ((ret = __cpufreq_governor(policy, CPUFREQ_GOV_START)) ||
+					(ret = __cpufreq_governor(policy, CPUFREQ_GOV_LIMITS))) {
+				pr_err("%s: Failed to start governor\n",
+						__func__);
+				return ret;
+			}
 		}
 	}
 
@@ -1912,7 +1936,7 @@
 			/* might be a policy change, too, so fall through */
 		}
 		pr_debug("governor: change or update limits\n");
-		__cpufreq_governor(policy, CPUFREQ_GOV_LIMITS);
+		ret = __cpufreq_governor(policy, CPUFREQ_GOV_LIMITS);
 	}
 
 error_out: