From owner-freebsd-arch@FreeBSD.ORG Tue Jul 20 19:10:43 2004 Return-Path: Delivered-To: freebsd-arch@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 0EFBD16A4DF; Tue, 20 Jul 2004 19:10:43 +0000 (GMT) Received: from pooker.samsco.org (pooker.samsco.org [168.103.85.57]) by mx1.FreeBSD.org (Postfix) with ESMTP id A3AF543D46; Tue, 20 Jul 2004 19:10:42 +0000 (GMT) (envelope-from scottl@samsco.org) Received: from [192.168.0.200] ([192.168.0.200]) (authenticated bits=0) by pooker.samsco.org (8.12.11/8.12.10) with ESMTP id i6KJGmSg059791; Tue, 20 Jul 2004 13:16:48 -0600 (MDT) (envelope-from scottl@samsco.org) Message-ID: <40FD6E25.1080808@samsco.org> Date: Tue, 20 Jul 2004 13:10:29 -0600 From: Scott Long User-Agent: Mozilla/5.0 (X11; U; FreeBSD i386; en-US; rv:1.7) Gecko/20040702 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Brian Fundakowski Feldman References: <20040720183213.GC1009@green.homeunix.org> <75604.1090348797@critter.freebsd.dk> <20040720185236.GD1009@green.homeunix.org> In-Reply-To: <20040720185236.GD1009@green.homeunix.org> X-Enigmail-Version: 0.84.2.0 X-Enigmail-Supports: pgp-inline, pgp-mime Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Status: No, hits=0.0 required=3.8 tests=none autolearn=no version=2.63 X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on pooker.samsco.org cc: arch@freebsd.org cc: Poul-Henning Kamp Subject: Re: kldunload DIAGNOSTIC idea... X-BeenThere: freebsd-arch@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Discussion related to FreeBSD architecture List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 20 Jul 2004 19:10:43 -0000 Brian Fundakowski Feldman wrote: > On Tue, Jul 20, 2004 at 08:39:57PM +0200, Poul-Henning Kamp wrote: > >>In message <20040720183213.GC1009@green.homeunix.org>, Brian Fundakowski Feldma >>n writes: >> >>>On Tue, Jul 20, 2004 at 08:20:23PM +0200, Poul-Henning Kamp wrote: >>> >>>>I'm pulling hair out trying to make it guaranteed safe to unload device >>>>driver modules, and the major pain here is to make sure there is no >>>>thread stuck somewhere inside the code. >>>> >>>>That gave me the idea for a simple little DIAGNOSTIC check for kldunload: >>>>run through the proc/thread table and look for any thread with an >>>>instruction counter inside the range of pages we are going to unload. >>>> >>>>Any takers ? >>> >>>You mean any thread with a stack trace that includes an instruction >>>counter inside those pages, don't you? >> >>That would require us to unwind the stack which I think is overkill >>for the purpose. >> >>The most likely case is that the thread is sleeping on something >>inside the kld so just checking the instruction pointer would be >>fine. >> >>Looking for sleep addresses inside the module might make sense too. > > > It's probably not overkill -- at least in my experience most of the > time a driver is "doing something" it is sleeping, so the address > will be in mi_switch() or somewhere way out there. Sleep addresses > on dynamic data addresses are also a lot more common than sleep > addresses on static/code addresses. If someone is interested in > doign this, it would be very informative, especially if it could > catch sleeps, pending timeouts, pending callouts, etc. > busdma callbacks, cam callbacks, netisr callbacks, and on and on and on. Scott