[RFQ] make witness panic an option

[Pawel Jakub Dawidek]

On Thu, Nov 15, 2012 at 04:39:55PM +0000, Attilio Rao wrote:
> On 11/15/12, Adrian Chadd <adrian at freebsd.org> wrote:
> > On 15 November 2012 05:27, Giovanni Trematerra
> > <giovanni.trematerra at gmail.com> wrote:
> >
> >> I really do think that is a very bad idea.
> >> When a locking assertion fails you have just to stop your mind and
> >> think what's wrong,
> >> no way to postpone on this.
> >
> > Not all witness panics are actually fatal. For a developer who is
> > sufficiently cluey in their area, they are quite likely able to just
> > stare at the code paths for a while to figure out why the
> > incorrectness occured.
> 
> The problem is that such mechanism can be abused, just like the
> BLESSING one and that's why this is disabled by default.

WITNESS is a development tool. We don't ship production kernels with
WITNESS even compiled in. What is more efficient use of developer time:
going through full reboot cycle every time or reading the warning from
console, unloading a module, fixing the bug and loading it again?

And if this option is turned off by default what is the problem?

-- 
Pawel Jakub Dawidek                       http://www.wheelsystems.com
FreeBSD committer                         http://www.FreeBSD.org
Am I Evil? Yes, I Am!                     http://tupytaj.pl
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