Experimental ttwwakeup() panic patch

[Doug White]

On Tue, 3 May 2005, Doug White wrote:

> Hey folks,
>
> I've taken a crack at working around the ttwwakeup() panic thats been
> reported now and again.  My early analysis, based on debugging output from
> rwatson, is that a defunct struct tty gets reused without cleaning out the
> associated (stale) knote structures, and the ttwwakeup() at the end of
> sioopen() jumps off into space when it finds them.
>
> This patch is against RELENG_5 but the logic should apply to -CURRENT,
> although the patch likely won't as ttymalloc() is organized differently
> there.
>
> I did some basic testing on my UP box and didn't see any abberant behavior
> afterwards. However I can't reproduce the panic in question, so if you're
> good at triggering the panic give this a spin.
>
> http://people.freebsd.org/~dwhite/tty.c.20050503.patch

This patch has been committed and exists as rev 1.228.2.4 of
src/sys/kern/tty.c.  Please let me know if this fixes the panic for you,
or causes new problems :)

-- 
Doug White                    |  FreeBSD: The Power to Serve
dwhite at gumbysoft.com          |  www.FreeBSD.org