MTX_DEF versus MTX_SPIN

[Andriy Gapon]

on 03/11/2010 18:27 mdf at FreeBSD.org said the following:
> It's not clear to me from the man pages (perhaps I didn't look at the
> right one?) in which environments I need a spinlock.  For example, I
> wouldn't think it's safe to use a MTX_DEF in a hard interrupt handler
> (i.e one that was registered with BUS_SETUP_INTR), but I see some code
> lying around here that does it and nothing I'm aware of has broken.

Such a handler runs in an interrupt thread.
The "harder" interrupt handler is called interrupt filter in FreeBSD terminology.
 I think that it was formerly known as fast interrupt.

-- 
Andriy Gapon