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From: Arjan van de Ven <arjan@linux.intel.com>
To: Peter Osterlund <petero2@telia.com>
Cc: Laurent Riffard <laurent.riffard@free.fr>,
	Kernel development list <linux-kernel@vger.kernel.org>,
	axboe@suse.de
Subject: Re: 2.6.17-rc6-mm1/pktcdvd - BUG: possible circular locking
Date: Sat, 15 Jul 2006 00:29:13 +0200	[thread overview]
Message-ID: <1152916153.3159.51.camel@laptopd505.fenrus.org> (raw)
In-Reply-To: <m3odvrc2vo.fsf@telia.com>


> 
> In the first call chain, do_open -> pkt_open, the bd_mutex object that
> is being locked corresponds to a pktcdvd block device, because those
> are the only devices that have their open method set to pkt_open.
> 
> In the second call chain, pkt_ctl_ioctl -> pkt_new_dev -> do_open, the
> bd_mutex object that is being locked *does not* correspond to a
> pktcdvd block device, because pkt_new_dev will bail out with a "Can't
> chain pktcdvd devices" error if you call it with "dev" set to a
> pktcdvd device.
> 
> Therefore, there is no AB-BA deadlock possibility. The locking
> dependencies are A -> B and B -> A', where it is known that A, B and
> A' are all different.
> 
> So the claim from the lockdep code, "BUG: possible circular locking
> deadlock detected!", is a false alarm.

ok I'll try to find a annotation for that that works

  reply	other threads:[~2006-07-14 22:29 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-06-08 19:09 2.6.17-rc6-mm1/pktcdvd - BUG: possible circular locking Laurent Riffard
2006-06-12 15:14 ` Arjan van de Ven
2006-06-12 16:41   ` Jens Axboe
2006-06-21 10:21     ` Arjan van de Ven
2006-06-22 14:50   ` Peter Osterlund
2006-06-22 18:20     ` Arjan van de Ven
2006-07-14 11:22       ` Peter Osterlund
2006-07-14 13:46         ` Arjan van de Ven
2006-07-14 21:06           ` Peter Osterlund
2006-07-14 22:29             ` Arjan van de Ven [this message]
2006-07-15  7:04             ` [patch] lockdep: annotate pktcdvd natural device hierarchy Arjan van de Ven
2006-07-15 10:35               ` Laurent Riffard
2006-07-15 10:57                 ` Peter Osterlund
2006-07-16 10:33                   ` Laurent Riffard
2006-07-25  2:27                     ` Andrew Morton
2006-07-25  5:34                       ` Arjan van de Ven
2006-07-25  6:31                         ` Andrew Morton

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