Linux Kernel kobject and kset

Like IUnknown in com

kobject  has:Parent , Name , Reference count 

A ktype is the type of object that embeds a kobject

A kset is a group of kobjects.

struct uio_mem {
    struct kobject kobj;
    unsigned long addr;
    unsigned long size;
    int memtype;
    void __iomem *internal_addr;
};

struct uio_mem *u_mem = container_of(kp, struct uio_mem, kobj);
 
Init:
 
void kobject_init(struct kobject *kobj, struct kobj_type *ktype);

Associate with the parent  

 
int kobject_add(struct kobject *kobj, struct kobject *parent, const char *fmt, ...);
 
Get the name :
 
const char *kobject_name(const struct kobject * kobj);
 
Uevents:
 
Notify the word about the new kobject 
 
int kobject_uevent(struct kobject *kobj, enum kobject_action action);
 
KOBJ_ADD or 
KOBJ_REMOVE 
 
 
Reference count:
 
Dec ref count :
void kobject_put(struct kobject *kobj);
 
Inc ref count
struct kobject *kobject_get(struct kobject *kobj);
 
 
Wrap function for creating kobjects 
 
struct kobject *kobject_create_and_add(char *name, struct kobject *parent);
 
a structure protected by a kobject cannot be freed
before its reference count goes to zero
 
Releasing kobject 
 
 void learn_object_release(struct kobject *kobj)
 {
            struct learn_object * thelearnobject = container_of(kobj, struct learn_object kobj);

//Concrate cleaning procedurs 

        kfree(thelearnobject );
 }
 
 
  struct kobj_type {
	    void (*release)(struct kobject *);
	    struct sysfs_ops	*sysfs_ops;
	    struct attribute	**default_attrs;
    };
 
 
kset 
associated kobject sets.
 
subdirectory in sysfs
 
create and delete a kset
 
 struct kset *kset_create_and_add(const char *name,
				   struct kset_uevent_ops *u,
				   struct kobject *parent);

  void kset_unregister(struct kset *kset);
 
 
In order to assoiate the kobject with a kset 
set the kobject kset member before creating the kobject 
 
 sample source
 
static struct foo_obj *create_foo_obj(const char *name)
 {
     struct foo_obj *foo;
     int retval;
 
     /* allocate the memory for the whole object */
     foo = kzalloc(sizeof(*foo), GFP_KERNEL);
     if (!foo)
         return NULL;
 
     /*
      * As we have a kset for this kobject, we need to set it before calling
      * the kobject core.
      */
     foo->kobj.kset = example_kset;
 
     /*
      * Initialize and add the kobject to the kernel.  All the default files
      * will be created here.  As we have already specified a kset for this
      * kobject, we don't have to set a parent for the kobject, the kobject
      * will be placed beneath that kset automatically.
      */
     retval = kobject_init_and_add(&foo->kobj, &foo_ktype, NULL, "%s", name);
     if (retval) {
         kobject_put(&foo->kobj);
         return NULL;
     }
 
     /*
      * We are always responsible for sending the uevent that the kobject
      * was added to the system.
      */
     kobject_uevent(&foo->kobj, KOBJ_ADD);
 
     return foo;
 }