kobject: Introduce struct kobj_type.

This is the first step in morphing struct subsystem into something meaningful.

A subsystem is defined simply as a list of kobjects of a certain type, which
is far too generic. A subsystem should be representative of a large entity
of code (i.e. a subsystem of the kernel), not just a simple list. 

This changeset:

- Creates struct kobj_type, a descriptor of the type a kobject is embedded
  in.

- Extracts the fields that are specific to a particular object type from
  struct subsystem and puts them in struct kobj_type, which are
  - the object's release method.
  - the sysfs operations for the object type.
  - the default attributes of the object type.

- Adds ptr to struct kobject to point to its type descriptor. 

- Converts the existing subsystem definitions to define struct kobj_type. 


struct kobj_type's are not registered, as they do not have any explicit
representation in the object hierarchy, nor do they have any fields that
need runtime initialization. 

A kobject's ktype should be set when it is registered, like its subsystem.
Note this obviates the need for defining a struct subsystem when an object
type does not need to be kept in a global list. 

1 files changed, 7 insertions, 3 deletions

diff --git a/include/linux/kobject.h b/include/linux/kobject.h
index 8a44ef867b35..e7a3f29135ff 100644
--- a/include/linux/kobject.h
+++ b/include/linux/kobject.h
@@ -20,6 +20,7 @@ struct kobject {
 	struct list_head	entry;
 	struct kobject		* parent;
 	struct subsystem	* subsys;
+	struct kobj_type	* ktype;
 	struct dentry		* dentry;
 };
 
@@ -36,14 +37,17 @@ extern struct kobject * kobject_get(struct kobject *);
 extern void kobject_put(struct kobject *);
 
 
+struct kobj_type {
+	void (*release)(struct kobject *);
+	struct sysfs_ops	* sysfs_ops;
+	struct attribute	** default_attrs;
+};
+
 struct subsystem {
 	struct kobject		kobj;
 	struct list_head	list;
 	struct rw_semaphore	rwsem;
 	struct subsystem	* parent;
-	void (*release)(struct kobject *);
-	struct sysfs_ops	* sysfs_ops;
-	struct attribute	** default_attrs;
 };
 
 extern void subsystem_init(struct subsystem *);