The kobj_type structure

This structure looks like:

struct kobj_type {
        void (*release)(struct kobject *);
        struct sysfs_ops        *sysfs_ops;
        struct attribute        **default_attrs;
};

When designing your object type
Create one or more release functions
cdev has two, for static and dynamic structures
Create an associated kobj_type structure
Store the ktype pointer for every object created
In kobject->ktype
...or in the kset