driver core: create a private portion of struct device

This is to be used to move things out of struct device that no code
outside of the driver core should ever touch.

Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/base/base.h

@@ -63,6 +63,18 @@ struct class_private {
 #define to_class(obj)	\
 	container_of(obj, struct class_private, class_subsys.kobj)
 
+/**
+ * struct device_private - structure to hold the private to the driver core portions of the device structure.
+ *
+ * @device - pointer back to the struct class that this structure is
+ * associated with.
+ *
+ * Nothing outside of the driver core should ever touch these fields.
+ */
+struct device_private {
+	struct device *device;
+};
+
 /* initialisation functions */
 extern int devices_init(void);
 extern int buses_init(void);

drivers/base/core.c

@@ -109,6 +109,7 @@ static struct sysfs_ops dev_sysfs_ops = {
 static void device_release(struct kobject *kobj)
 {
 	struct device *dev = to_dev(kobj);
+	struct device_private *p = dev->p;
 
 	if (dev->release)
 		dev->release(dev);
@@ -120,6 +121,7 @@ static void device_release(struct kobject *kobj)
 		WARN(1, KERN_ERR "Device '%s' does not have a release() "
 			"function, it is broken and must be fixed.\n",
 			dev_name(dev));
+	kfree(p);
 }
 
 static struct kobj_type device_ktype = {
@@ -859,6 +861,13 @@ int device_add(struct device *dev)
 	if (!dev)
 		goto done;
 
+	dev->p = kzalloc(sizeof(*dev->p), GFP_KERNEL);
+	if (!dev->p) {
+		error = -ENOMEM;
+		goto done;
+	}
+	dev->p->device = dev;
+
 	/*
 	 * for statically allocated devices, which should all be converted
 	 * some day, we need to initialize the name. We prevent reading back

include/linux/device.h

@@ -28,6 +28,7 @@
 #define BUS_ID_SIZE		20
 
 struct device;
+struct device_private;
 struct device_driver;
 struct driver_private;
 struct class;
@@ -373,6 +374,8 @@ struct device {
 	struct klist_node	knode_bus;
 	struct device		*parent;
 
+	struct device_private	*p;
+
 	struct kobject kobj;
 	unsigned		uevent_suppress:1;
 	const char		*init_name; /* initial name of the device */