From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756169AbYG2SHM (ORCPT ); Tue, 29 Jul 2008 14:07:12 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752040AbYG2SG6 (ORCPT ); Tue, 29 Jul 2008 14:06:58 -0400 Received: from accolon.hansenpartnership.com ([76.243.235.52]:60364 "EHLO accolon.hansenpartnership.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750885AbYG2SG6 (ORCPT ); Tue, 29 Jul 2008 14:06:58 -0400 Subject: Re: Subtle but oops causing problem with class_device->device conversion From: James Bottomley To: Kay Sievers Cc: Hannes Reinecke , linux-scsi , linux-kernel In-Reply-To: <1217354388.31362.2.camel@linux.site> References: <1217353348.6103.20.camel@localhost.localdomain> <1217354388.31362.2.camel@linux.site> Content-Type: text/plain Date: Tue, 29 Jul 2008 13:06:30 -0500 Message-Id: <1217354790.6103.36.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.22.3.1 (2.22.3.1-1.fc9) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2008-07-29 at 19:59 +0200, Kay Sievers wrote: > On Tue, 2008-07-29 at 12:42 -0500, James Bottomley wrote: > > It's taken me a while to track this down. Basically there's an oops in > > scsi_transport_spi that's directly caused by this. > > > > What happened is that you made all class devices become real devices and > > be parented to devices they were formerly allied to through the class > > device dev pointer. This means that effectively you expanded the child > > list of every device to include not only its real children but also its > > class devices. > > > > This breaks in device_for_each_child *if* the routine in the iterator > > doesn't perform checks on the devices it gets back (scsi_transport_spi > > was assuming that every device it got was embedded in a struct > > scsi_device because they're the only logical children of a scsi_target). > > > > I can fix the SCSI breakage, but the whole tree will need auditing to > > check that nothing else is using this assumption. > > I guess it's caused by: > [SCSI] add scsi_host and scsi_target to scsi_bus > > This patch implements scsi_host and scsi_target device types > and adds both to the scsi_bus. > http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=b0ed43360fdca227048d88a08290365cb681c1a8 > > and not by the re-parenting, so it should be limited to SCSI, right? No .. read the email. It's caused by adding extra children to the device via the class_device conversion. device_for_each_child doesn't care what the type is (although that might be a potential generic fix for this). So, it's definitely not confined to SCSI. James