cpufreq:governor: Add serialization to the cpufreq_governor_dbs() function

It is necessary to serialize access to cpufreq_governor_dbs() function, since
it can be accessed from different, not protected by any mutex paths like
sysfs boost attribute or LAB governor internals.

Change-Id: Id7b62db6ca0b7c28f5e8c6286aec312d3d0c971e
Signed-off-by: Lukasz Majewski <l.majewski@samsung.com>

diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c
index 9b7352c..e62e94f 100644 (file)
--- a/drivers/cpufreq/cpufreq_governor.c
+++ b/drivers/cpufreq/cpufreq_governor.c
@@ -28,6 +28,7 @@
 #include <linux/workqueue.h>
 
 #include "cpufreq_governor.h"
+static DEFINE_MUTEX(cpufreq_governor_lock);
 
 static struct kobject *get_governor_parent_kobj(struct cpufreq_policy *policy)
 {
@@ -250,6 +251,7 @@ int cpufreq_governor_dbs(struct cpufreq_policy *policy,
        int rc;
        int governor = cdata->governor;
 
+       mutex_lock(&cpufreq_governor_lock);
        if (have_governor_per_policy())
                dbs_data = policy->governor_data;
        else
@@ -264,12 +266,14 @@ int cpufreq_governor_dbs(struct cpufreq_policy *policy,
                } else if (dbs_data) {
                        dbs_data->usage_count++;
                        policy->governor_data = dbs_data;
+                       mutex_unlock(&cpufreq_governor_lock);
                        return 0;
                }
 
                dbs_data = kzalloc(sizeof(*dbs_data), GFP_KERNEL);
                if (!dbs_data) {
                        pr_err("%s: POLICY_INIT: kzalloc failed\n", __func__);
+                       mutex_unlock(&cpufreq_governor_lock);
                        return -ENOMEM;
                }
 
@@ -279,6 +283,7 @@ int cpufreq_governor_dbs(struct cpufreq_policy *policy,
                if (rc) {
                        pr_err("%s: POLICY_INIT: init() failed\n", __func__);
                        kfree(dbs_data);
+                       mutex_unlock(&cpufreq_governor_lock);
                        return rc;
                }
 
@@ -290,6 +295,7 @@ int cpufreq_governor_dbs(struct cpufreq_policy *policy,
                if (rc) {
                        cdata->exit(dbs_data);
                        kfree(dbs_data);
+                       mutex_unlock(&cpufreq_governor_lock);
                        return rc;
                }
 
@@ -317,6 +323,7 @@ int cpufreq_governor_dbs(struct cpufreq_policy *policy,
                if (!have_governor_per_policy())
                        cdata->gdbs_data = dbs_data;
 
+               mutex_unlock(&cpufreq_governor_lock);
                return 0;
        case CPUFREQ_GOV_POLICY_EXIT:
                if (!--dbs_data->usage_count) {
@@ -340,6 +347,7 @@ int cpufreq_governor_dbs(struct cpufreq_policy *policy,
                }
 
                policy->governor_data = NULL;
+               mutex_unlock(&cpufreq_governor_lock);
                return 0;
        }
 
@@ -347,9 +355,10 @@ int cpufreq_governor_dbs(struct cpufreq_policy *policy,
 
        switch (event) {
        case CPUFREQ_GOV_START:
-               if (!policy->cur)
+               if (!policy->cur) {
+                       mutex_unlock(&cpufreq_governor_lock);
                        return -EINVAL;
-
+               }
                if (governor == GOV_CONSERVATIVE) {
                        cs_tuners = dbs_data->tuners;
                        cs_dbs_info = dbs_data->cdata->get_cpu_dbs_info_s(cpu);
@@ -423,6 +432,7 @@ int cpufreq_governor_dbs(struct cpufreq_policy *policy,
                mutex_unlock(&cpu_cdbs->timer_mutex);
                break;
        }
+       mutex_unlock(&cpufreq_governor_lock);
        return 0;
 }
 EXPORT_SYMBOL_GPL(cpufreq_governor_dbs);