Queuing

Placing yourself in the waitqueue is fairly complex, because you must put yourself in the queue before checking the condition. There is a macro to do this: wait_event_interruptible() include/linux/sched.h The first argument is the wait queue head, and the second is an expression which is evaluated; the macro returns 0 when this expression is true, or -ERESTARTSYS if a signal is received. The wait_event() version ignores signals.