In a shared memory application, developers must ensure that shared resources are protected from concurrent access. The kernel is no exception. Shared resources require protection from concurrent access because if multiple threads of execution1 access and manipulate the data at the same time, the threads may overwrite each other’s changes or access data while it is in an inconsistent state. Concurrent access of shared data is a recipe for instability that often proves hard to track down and debug—getting it right at the start is important.
