1 files changed, 47 insertions, 9 deletions

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index bb63347f6af1..d8fc395af773 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -250,6 +250,51 @@ void cpufreq_cpu_put(struct cpufreq_policy *policy)
 }
 EXPORT_SYMBOL_GPL(cpufreq_cpu_put);
 
+/**
+ * cpufreq_cpu_release - Unlock a policy and decrement its usage counter.
+ * @policy: cpufreq policy returned by cpufreq_cpu_acquire().
+ */
+static void cpufreq_cpu_release(struct cpufreq_policy *policy)
+{
+        if (WARN_ON(!policy))
+                return;
+
+        lockdep_assert_held(&policy->rwsem);
+
+        up_write(&policy->rwsem);
+
+        cpufreq_cpu_put(policy);
+}
+
+/**
+ * cpufreq_cpu_acquire - Find policy for a CPU, mark it as busy and lock it.
+ * @cpu: CPU to find the policy for.
+ *
+ * Call cpufreq_cpu_get() to get a reference on the cpufreq policy for @cpu and
+ * if the policy returned by it is not NULL, acquire its rwsem for writing.
+ * Return the policy if it is active or release it and return NULL otherwise.
+ *
+ * The policy returned by this function has to be released with the help of
+ * cpufreq_cpu_release() in order to release its rwsem and balance its usage
+ * counter properly.
+ */
+static struct cpufreq_policy *cpufreq_cpu_acquire(unsigned int cpu)
+{
+        struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
+
+        if (!policy)
+                return NULL;
+
+        down_write(&policy->rwsem);
+
+        if (policy_is_inactive(policy)) {
+                cpufreq_cpu_release(policy);
+                return NULL;
+        }
+
+        return policy;
+}
+
 /*********************************************************************
  *            EXTERNALLY AFFECTING FREQUENCY CHANGES                 *
  *********************************************************************/
@@ -2337,17 +2382,12 @@ static int cpufreq_set_policy(struct cpufreq_policy *policy,
  */
 void cpufreq_update_policy(unsigned int cpu)
 {
-        struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
+        struct cpufreq_policy *policy = cpufreq_cpu_acquire(cpu);
         struct cpufreq_policy new_policy;
 
         if (!policy)
                 return;
 
-        down_write(&policy->rwsem);
-
-        if (policy_is_inactive(policy))
-                goto unlock;
-
         /*
          * BIOS might change freq behind our back
          * -> ask driver for current freq and notify governors about a change
@@ -2364,9 +2404,7 @@ void cpufreq_update_policy(unsigned int cpu)
         cpufreq_set_policy(policy, &new_policy);
 
 unlock:
-        up_write(&policy->rwsem);
-
-        cpufreq_cpu_put(policy);
+        cpufreq_cpu_release(policy);
 }
 EXPORT_SYMBOL(cpufreq_update_policy);