2 files changed, 33 insertions, 2 deletions

diff --git a/drivers/cpuidle/driver.c b/drivers/cpuidle/driver.c
index 40cd3f3024df..58bf3b1ac9c4 100644
--- a/drivers/cpuidle/driver.c
+++ b/drivers/cpuidle/driver.c
@@ -16,6 +16,7 @@
 
 static struct cpuidle_driver *cpuidle_curr_driver;
 DEFINE_SPINLOCK(cpuidle_driver_lock);
+int cpuidle_driver_refcount;
 
 static void __cpuidle_register_driver(struct cpuidle_driver *drv)
 {
@@ -89,8 +90,34 @@ void cpuidle_unregister_driver(struct cpuidle_driver *drv)
         }
 
         spin_lock(&cpuidle_driver_lock);
-        cpuidle_curr_driver = NULL;
+
+        if (!WARN_ON(cpuidle_driver_refcount > 0))
+                cpuidle_curr_driver = NULL;
+
         spin_unlock(&cpuidle_driver_lock);
 }
 
 EXPORT_SYMBOL_GPL(cpuidle_unregister_driver);
+
+struct cpuidle_driver *cpuidle_driver_ref(void)
+{
+        struct cpuidle_driver *drv;
+
+        spin_lock(&cpuidle_driver_lock);
+
+        drv = cpuidle_curr_driver;
+        cpuidle_driver_refcount++;
+
+        spin_unlock(&cpuidle_driver_lock);
+        return drv;
+}
+
+void cpuidle_driver_unref(void)
+{
+        spin_lock(&cpuidle_driver_lock);
+
+        if (!WARN_ON(cpuidle_driver_refcount <= 0))
+                cpuidle_driver_refcount--;
+
+        spin_unlock(&cpuidle_driver_lock);
+}
diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
index 8570012a535a..27cfced7b57b 100644
--- a/include/linux/cpuidle.h
+++ b/include/linux/cpuidle.h
@@ -136,7 +136,9 @@ struct cpuidle_driver {
 extern void disable_cpuidle(void);
 extern int cpuidle_idle_call(void);
 extern int cpuidle_register_driver(struct cpuidle_driver *drv);
-struct cpuidle_driver *cpuidle_get_driver(void);
+extern struct cpuidle_driver *cpuidle_get_driver(void);
+extern struct cpuidle_driver *cpuidle_driver_ref(void);
+extern void cpuidle_driver_unref(void);
 extern void cpuidle_unregister_driver(struct cpuidle_driver *drv);
 extern int cpuidle_register_device(struct cpuidle_device *dev);
 extern void cpuidle_unregister_device(struct cpuidle_device *dev);
@@ -157,6 +159,8 @@ static inline int cpuidle_idle_call(void) { return -ENODEV; }
 static inline int cpuidle_register_driver(struct cpuidle_driver *drv)
 {return -ENODEV; }
 static inline struct cpuidle_driver *cpuidle_get_driver(void) {return NULL; }
+static inline struct cpuidle_driver *cpuidle_driver_ref(void) {return NULL; }
+static inline void cpuidle_driver_unref(void) {}
 static inline void cpuidle_unregister_driver(struct cpuidle_driver *drv) { }
 static inline int cpuidle_register_device(struct cpuidle_device *dev)
 {return -ENODEV; }