How is this pattern any different from "keep interrupts disabled all the time except when the program is ready to yield()"? I'm not really seeing the inherent difference w/ the well-known pitfalls of multi-threaded programming. The defining characteristics of signals is that, like interrupts and multi-threaded execution, they can pre-empt your program at any time. (Synchronous signals as you describe them are indeed different, they look more like a "recoverable exceptions" system.)