From owner-freebsd-current@FreeBSD.ORG Thu Sep 15 18:56:32 2005 Return-Path: X-Original-To: current@freebsd.org Delivered-To: freebsd-current@FreeBSD.ORG Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 05AE416A41F; Thu, 15 Sep 2005 18:56:32 +0000 (GMT) (envelope-from jhb@FreeBSD.org) Received: from mv.twc.weather.com (mv.twc.weather.com [65.212.71.225]) by mx1.FreeBSD.org (Postfix) with ESMTP id 6941243D45; Thu, 15 Sep 2005 18:56:31 +0000 (GMT) (envelope-from jhb@FreeBSD.org) Received: from [10.50.41.233] (Not Verified[10.50.41.233]) by mv.twc.weather.com with NetIQ MailMarshal (v6, 0, 3, 8) id ; Thu, 15 Sep 2005 15:12:11 -0400 From: John Baldwin To: freebsd-current@freebsd.org Date: Thu, 15 Sep 2005 14:56:49 -0400 User-Agent: KMail/1.8 References: <200509022137.j82LbUj2024170@gw.catspoiler.org> In-Reply-To: <200509022137.j82LbUj2024170@gw.catspoiler.org> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200509151456.50584.jhb@FreeBSD.org> Cc: Don Lewis , rwatson@freebsd.org, current@freebsd.org Subject: Re: Witness patch X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 15 Sep 2005 18:56:32 -0000 On Friday 02 September 2005 05:37 pm, Don Lewis wrote: > On 2 Sep, John Baldwin wrote: > > On Thursday 01 September 2005 11:52 pm, Don Lewis wrote: > >> On 1 Sep, John Baldwin wrote: > >> > This patch forces witness to complain if any mutex is held when Giant > >> > is locked to enforce Giant being the first mutex in the lock order. > >> > This might help track down some of the network LORs being reported > >> > recently. > >> > > >> > http://www.FreeBSD.org/~jhb/patches/witness.patch > >> > >> I think it would make sense to print different messages for the > >> different trigger conditions. > > > > Hmm, I guess I view them as all just being reversals, and that we have > > some implicit orders that go something like this: > > > > sleepable locks --> Giant --> non-sleepable locks --> spin locks > > Attempting to lock one one of the other lock types while holding a spin > lock already prints a unique message and results in a panic. Identifying > the other cases of incorrect lock type ordering with a unique warning > message eliminates the need to grovel through the source code just to > find the types of the locks, and it indicates that looking at the output > of "show witness" is not needed. Ok. I'll still list the reversal (so you know which locks are involved) but will tailor the first line to include the implicit rule in parens if the reversal is the result of an implicit rule. -- John Baldwin <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve" = http://www.FreeBSD.org