Re: Freeing a dynamic struct cdev

["James C. Georgas" <jgeorgas@rogers.com>]

Ok, I really blew it with that last post:

> 
> cdev_add() calls:
> 	kobj_map()
> 	kobject_get() [indirectly]
> 

This is wrong. When I first looked at it, I saw:

cdev_add() -> kobj_map() -> exact_lock() -> cdev_get() -> kobject_get()

but exact_lock() isn't called here; it is only passed as a function
pointer to kobj_map(), and so calling cdev_add() does /not/ increment
the reference count of the struct cdev.

I guess what threw me for a loop here was that I was expecting separate
functions: one to undo cdev_add() and one to undo cdev_alloc(), but
cdev_del() accomplishes both tasks in one function, with the
kobj_unmap() part having no effect, if the cdev is not mapped at the
time of the call.

-- 
James C. Georgas <jgeorgas@rogers.com>