From owner-freebsd-hackers@FreeBSD.ORG Sun Nov 25 12:38:10 2012 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id A3272E3B; Sun, 25 Nov 2012 12:38:10 +0000 (UTC) (envelope-from pawel@dawidek.net) Received: from mail.dawidek.net (garage.dawidek.net [91.121.88.72]) by mx1.freebsd.org (Postfix) with ESMTP id 5CB6F8FC19; Sun, 25 Nov 2012 12:38:09 +0000 (UTC) Received: from localhost (89-73-195-149.dynamic.chello.pl [89.73.195.149]) by mail.dawidek.net (Postfix) with ESMTPSA id 19DBAC33; Sun, 25 Nov 2012 13:36:21 +0100 (CET) Date: Sun, 25 Nov 2012 13:39:21 +0100 From: Pawel Jakub Dawidek To: Attilio Rao Subject: Re: [RFQ] make witness panic an option Message-ID: <20121125123920.GI1460@garage.freebsd.pl> References: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="EdRE1UL8d3mMOE6m" Content-Disposition: inline In-Reply-To: X-OS: FreeBSD 10.0-CURRENT amd64 User-Agent: Mutt/1.5.21 (2010-09-15) Cc: "freebsd-hackers@freebsd.org" , Adrian Chadd , Giovanni Trematerra , freebsd-arch@freebsd.org X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 25 Nov 2012 12:38:10 -0000 --EdRE1UL8d3mMOE6m Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Nov 15, 2012 at 04:39:55PM +0000, Attilio Rao wrote: > On 11/15/12, Adrian Chadd wrote: > > On 15 November 2012 05:27, Giovanni Trematerra > > 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. >=20 > 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? --=20 Pawel Jakub Dawidek http://www.wheelsystems.com FreeBSD committer http://www.FreeBSD.org Am I Evil? Yes, I Am! http://tupytaj.pl --EdRE1UL8d3mMOE6m Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.19 (FreeBSD) iEYEARECAAYFAlCyEXgACgkQForvXbEpPzRdpwCbBmzAAu4KdDaHCcDdEr/xq5SE HDwAoMpyO7TPU8jPupmwrg1EgSJXLljn =gpTY -----END PGP SIGNATURE----- --EdRE1UL8d3mMOE6m--