ath (AR9460) no longer works after going to 11-STABLE r302483

[Wolfgang Zenker]

* Adrian Chadd <adrian at freebsd.org> [160716 17:52]:
> ...

> I'm confused as to what's going on..

smells like a race condition unmasked by changed timing to me.
But I admit I have no clue at all how that wlan stuff works and if
it is even possible for such a race condition to exist, much less
how to debug this.

> On 16 July 2016 at 02:30, Wolfgang Zenker <wolfgang at lyxys.ka.sub.org> wrote:
> > Hi,
> >
> > * Adrian Chadd <adrian at freebsd.org> [160715 22:40]:
> >> On 15 July 2016 at 13:28, Wolfgang Zenker <wolfgang at lyxys.ka.sub.org> wrote:
> >>> * Adrian Chadd <adrian at freebsd.org> [160715 00:00]:
> >>>> On 14 July 2016 at 14:37, Wolfgang Zenker <wolfgang at lyxys.ka.sub.org> wrote:
> >>>>> * Adrian Chadd <adrian at freebsd.org> [160710 21:47]:
> >>>>>> Since you've reverted the ath driver directories without success, I'm
> >>>>>> mostly out of simple ideas. I think you need to bisect the whole
> >>>>>> kernel version until you find the commit that broke things.
> >
> >>>>> done. The commit is 11-STABLE r302410. AFAICS the only change here
> >>>>> is the removal of debugging options from the GENERIC kernel config:
> >
> >>>>> https://svnweb.freebsd.org/base/stable/11/sys/amd64/conf/GENERIC?r1=302408&r2=302410
> >
> >>>> ... loool, okay. Let me see.
> >
> >>>> Try INVARIANTS and INVARIANT_SUPPORT. Maybe something in the ath
> >>>> driver needs it.. oops!
> >
> >>> Nope, wlan0 still works after disabling INVARIANTS and INVARIANT_SUPPORT.
> >>> Any suggestions for next try?
> >
> >> Just try disabling the others and see what happens.
> >
> > commenting out DEADLKRES and MALLOC_DEBUG_MAXZONES in addition to
> > INVARIANTS and INVARIANT_SUPPORT did not change the situation: ath
> > still worked. Re-enabling all of the above and disabling WITNESS
> > resulted in ath failing.
> >
> > Wolfgang