PM / cpuidle: Add driver reference counter

Add a reference counter for the cpuidle driver, so that it can't
be unregistered when it is in use.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

diff --git a/drivers/cpuidle/driver.c b/drivers/cpuidle/driver.c
index 40cd3f3024df4031f65a118a43e147e8e1b678bf..58bf3b1ac9c46035c2a3fae79271954f6d436442 100644 (file)
--- 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 8570012a535ad0364c1555b16932e8589049bcc6..27cfced7b57bac1c00e5e538d2f62dcbf4a50907 100644 (file)
--- 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; }