signal handler priority issue

[Sean McNeil]

> No, the problem is because SIGUSR2 is _not_ blocked.  I read
> "masked off" as "blocked" (the desired behavior).  If the
> signal handler runs, that means that the signal is not blocked.
> Your goal is to prevent the signal handler (for SIGUSR2) from
> running until sigsuspend() is hit.  Once sigsuspend() is hit,
> then SIGUSR2 becomes unblocked, the signal handler is run,
> and sigsuspend() returns.

This is exactly what boehm-gc is doing.  There must be something else
lurking in here that I've missed.  I have to keep looking at it.