How the hierarchy works

There are two more kobject pointers
->kset (the kset containing this kobject)
->parent (the parent kobject)

The kset pointer
Locates the container for a kobject
Is used to find the ktype pointer
Is used for hotplug operations
Implication: kobjects belong to at most one kset

The parent pointer
Locates the kobject in sysfs

Usually:
kobject->parent == &kobject->kset->kobj