Real Time Preemption changes being planned for 2.6

Paul McKenney with whom I had a good time interacting in Sequent, has written a great article on Real Time Preemption at A Real Time preemption Overview

These changes obsolete many things that have been said about Locking in Linux. As they say in the open source world

"If there is a book on it, the topic is obsolete"

I would highly recommend reading this article