Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759150AbYFISEe (ORCPT ); Mon, 9 Jun 2008 14:04:34 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755529AbYFISEQ (ORCPT ); Mon, 9 Jun 2008 14:04:16 -0400 Received: from mtagate7.de.ibm.com ([195.212.29.156]:2568 "EHLO mtagate7.de.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755073AbYFISEP (ORCPT ); Mon, 9 Jun 2008 14:04:15 -0400 Date: Mon, 9 Jun 2008 20:03:26 +0200 From: Cornelia Huck To: Linus Torvalds Cc: Ingo Molnar , Vegard Nossum , Adrian Bunk , Andrew Morton , Linux Kernel Mailing List , Jens Axboe , Greg Kroah-Hartman , "Rafael J. Wysocki" , Kay Sievers , Neil Brown , Mariusz Kozlowski , Dave Young Subject: Re: [bug, 2.6.26-rc4/rc5] sporadic bootup crashes in blk_lookup_devt()/prepare_namespace() Message-ID: <20080609200326.7530dd7a@gondolin.boeblingen.de.ibm.com> In-Reply-To: <20080609191521.1a56b6a6@gondolin.boeblingen.de.ibm.com> References: <20080609080312.GA32458@elte.hu> <20080609020623.b6727f2b.akpm@linux-foundation.org> <19f34abd0806090209l541d93c6jaba2704314b34418@mail.gmail.com> <20080609133426.GB20194@cs181133002.pp.htv.fi> <19f34abd0806090658v54f3a912n2ed30ad6cc20d00@mail.gmail.com> <19f34abd0806090728s3b3fdbeq7dd3d31d02c8f28e@mail.gmail.com> <20080609165757.184724ff@gondolin.boeblingen.de.ibm.com> <20080609153856.GA5149@elte.hu> <20080609191521.1a56b6a6@gondolin.boeblingen.de.ibm.com> Organization: IBM Deutschland Entwicklung GmbH Vorsitzender des Aufsichtsrats: Martin Jetter =?ISO-8859-15?Q?Gesch=E4ftsf=FChrung:?= Herbert Kircher Sitz der Gesellschaft: =?ISO-8859-15?Q?B=F6blingen?= Registergericht: Amtsgericht Stuttgart, HRB 243294 X-Mailer: Claws Mail 3.4.0 (GTK+ 2.12.10; i486-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1838 Lines: 47 On Mon, 9 Jun 2008 19:15:21 +0200, Cornelia Huck wrote: > On Mon, 9 Jun 2008 09:15:40 -0700 (PDT), > Linus Torvalds wrote: > > > And this is all still ignoring the locking issue, of course. It would be > > trivial to just remove the block_class_lock, and change > > > > mutex_[un]lock(&block_class_lock); > > > > into > > > > down|up(&block_class.sem); > > > > except for _one_ case, which is > > > > bdev_map = kobj_map_init(base_probe, &block_class_lock); > > > > which really wants a mutex, not a sempahore. > > > > So to fix that, we'd need to make the class->sem be a mutex, and pass that > > in. Which is probably a good change too, but makes the whole thing much > > bigger. > > The driver core changes in -next convert class->sem to > class->p->class_mutex, which makes it non-accessible to drivers. > Most of the locking is easily done through converting to the class > iterator functions, but there are some cases where this is not going to > work: > > - The {register,unregister}_blkdev() functions, which don't directly > involve the class. > - The iterators for /proc/partitions, which take the lock in > part_start() and give it up again in part_stop(). > > Maybe we need a possibilty for a driver to lock a class from outside? Argh. I was just trying to hack up a patch when I realized that we had to get a reference on the dynamic private structure when we take the lock - which made the patch so ugly that I dare not post it. I'll see if I have a better idea tomorrow (or someone beats me to it :) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/