But you still need locks! When you write data to a buffer you should lock the buffer (or if there are two of them, lock the variable that indicates which one is currently used). Also do so when reading from the buffer, or you'll get sooner or later hard to reproduce crashes...
well, you don't need locks to synchronize two threads ...
the lockfree fifos, that are used to place the idle callbacks in devels's main thread, are safe to be used from different threads ...
cheers ... tim