Compare this with SpinLock.

This is not very optimal, I think this a very simple solution that has no RaceCondition or DeadLock problem:

if ( lock.isLocked() )
 {
   CLI // Avoid ContextChange
   for ( int i = 0; i < 200 && lock.isLocked(); i++ )
     ;
   STI
 }
 lock.waitForLock(); // Either lock immediately or do a ContextChange until lock is taken
 doTask();
 lock.dropLock();
----
This won't work on a multi-cpu where context change does not take place through IRQs.