Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932416Ab1EJIOK (ORCPT ); Tue, 10 May 2011 04:14:10 -0400 Received: from mx1.redhat.com ([209.132.183.28]:12525 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753047Ab1EJIOH (ORCPT ); Tue, 10 May 2011 04:14:07 -0400 Date: Tue, 10 May 2011 13:43:53 +0530 From: Amit Shah To: Jens Axboe Cc: Tejun Heo , David Zeuthen , Martin Pitt , Kay Sievers , linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] cdrom: always check_disk_change() on open Message-ID: <20110510081353.GB22655@amit-x200.redhat.com> References: <20110406121920.GC4142@mtj.dyndns.org> <20110429060200.GA5107@amit-x200.redhat.com> <4DBA73B6.6040603@kernel.dk> <20110510064247.GA16436@amit-x200.redhat.com> <4DC8ECDC.5080106@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4DC8ECDC.5080106@kernel.dk> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1997 Lines: 48 On (Tue) 10 May 2011 [09:44:28], Jens Axboe wrote: > On 2011-05-10 08:42, Amit Shah wrote: > > On (Fri) 29 Apr 2011 [10:15:50], Jens Axboe wrote: > >> On 2011-04-29 08:57, Amit Shah wrote: > >>> On (Wed) 06 Apr 2011 [05:20:09], Tejun Heo wrote: > >>>> cdrom_open() called check_disk_change() after the rest of open path > >>>> succeeded which leads to the following bizarre behavior. > >>>> > >>>> * After media change, if the device opened without O_NONBLOCK, > >>>> open_for_data() naturally fails with -ENOMEDIA and > >>>> check_disk_change() is never called. The media is known to be gone > >>>> and the open failure makes it obvious to the userland but device > >>>> invalidation never happens. > >>>> > >>>> * But if the device is opened with O_NONBLOCK, all the checks are > >>>> bypassed and cdrom_open() doesn't notice that the media is not there > >>>> and check_disk_change() is called and invalidation happens. > >>>> > >>>> There's nothing to be gained by avoiding calling check_disk_change() > >>>> on open failure. Common cases end up calling check_disk_change() > >>>> anyway. All we get is inconsistent behavior. > >>>> > >>>> Fix it by moving check_disk_change() invocation to the top of > >>>> cdrom_open() so that it always gets called regardless of how the rest > >>>> of open proceeds. > >>>> > >>>> Signed-off-by: Tejun Heo > >>>> Reported-by: Amit Shah > >>>> Tested-by: Amit Shah > >>> > >>> Ping? > >>> > >>> Also, please mark this for stable-2.6.38. > >> > >> Done, added for 2.6.39 and marked stable for 2.6.38. > > > > Ping again. Don't see this yet in Linus's git tree. > > It was added for 2.6.40 and marked for stable. OK, Thanks. Amit -- 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/