Oki doki, thanks. I was a little confused by the example at that section and couldn't find any other references to "audit_netlink_sem" (though it is/was probably just a common semaphore, I guess). Ok, quick searching of list_del_rcu() in the kernel code (via http://lxr.linux.no/linux) cleared things up.
You might also find this useful:
http://lwn.net/Articles/421425/
Andrew