driver core: Move driver_data back to struct device

Having to allocate memory as part of dev_set_drvdata() is a problem
because that memory may never get freed if the device itself is not
created. So move driver_data back to struct device.

This is a partial revert of commit b4028437.

Signed-off-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/base/base.h

@@ -63,8 +63,6 @@ struct driver_private {
  *	binding of drivers which were unable to get all the resources needed by
  *	the device; typically because it depends on another driver getting
  *	probed first.
- * @driver_data - private pointer for driver specific info.  Will turn into a
- * list soon.
  * @device - pointer back to the struct class that this structure is
  * associated with.
  *
@@ -76,7 +74,6 @@ struct device_private {
 	struct klist_node knode_driver;
 	struct klist_node knode_bus;
 	struct list_head deferred_probe;
-	void *driver_data;
 	struct device *device;
 };
 #define to_device_private_parent(obj)	\

drivers/base/dd.c

@@ -594,22 +594,15 @@ void driver_detach(struct device_driver *drv)
  */
 void *dev_get_drvdata(const struct device *dev)
 {
-	if (dev && dev->p)
-		return dev->p->driver_data;
+	if (dev)
+		return dev->driver_data;
 	return NULL;
 }
 EXPORT_SYMBOL(dev_get_drvdata);
 
 int dev_set_drvdata(struct device *dev, void *data)
 {
-	int error;
-
-	if (!dev->p) {
-		error = device_private_init(dev);
-		if (error)
-			return error;
-	}
-	dev->p->driver_data = data;
+	dev->driver_data = data;
 	return 0;
 }
 EXPORT_SYMBOL(dev_set_drvdata);