This patch was my first attempt in kernel hacking. The “challenge” was to implement a function lwkt_token_is_stale that determines whether a serializing token got stale while a light weight kernel thread (LWKT) is sleeping. Serializing tokens in DragonFlyBSD are a very nice concept for synchronizing data access. It’s somewhat integrated with the LWKT scheduler so that I had to understand that code prior of being able to make any modifications.