Daniel O'Connor wrote:
On Sun, 20 Feb 2005 16:12, Peter Jeremy wrote:
I have a hardware interrupt handler that has to forward a signal to
userland and that I'd like to mark INTR_FAST. AFAIK, the normal way
to forward a signal is:
if ((p = pfind(sc->pid_to_signal)) != NULL) {
psignal(p, SIGUSR2);
PROC_UNLOCK(p);
}
But pfind(9) does a PROC_LOCK() which implies it can sleep and therefore
can't be used by an INTR_FAST handler.
Firstly, am I correct? If so, is there an alternative approach I can use?
I think you are, and I think the only way to do it is to schedule another
kernel [heavy] thread to do the wakeup.
You can shift the operation off to a fast taskqueue. This assumes that
latency between the interrupt and the signal delivery is not critical.
Scott
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