Linux RCU和双链表

I'm reading about Read-copy-update (RCU). I'm not sure if I understood it correctly in case of SMP. As far as I know RCU ensures that Update is executed atomically. In case for example single linked list it is obvious that exchanging old element with the new one can be done in one operation, because it is done by changing pointer. But how to ensure that RCU will still be atomically executed in case of doubly-linked list? There are two pointers points to given element (next and prev), so every change on this element needs to change those two pointers. How to ensure that changing those two pointers will be done as atomic operation? How it is done in Linux?. I'm n