Kernel Bug Tracker – Bug 28052
[BUG] 2.6.38-rc2: Circular Locking Dependency
Last modified: 2011-02-13 23:42:05 UTC
Subject : [BUG] 2.6.38-rc2: Circular Locking Dependency
Submitter : Knut Petersen <Knut_Petersen@t-online.de>
Date : 2011-01-24 9:25
Message-ID : 4D3D45A3.email@example.com
References : http://marc.info/?l=linux-kernel&m=129586118515443&w=2
This entry is being used for tracking a regression from 2.6.37. Please don't
close it until the problem is fixed in the mainline.
On Sunday, February 13, 2011, David Miller wrote:
> From: "Rafael J. Wysocki" <firstname.lastname@example.org>
> Date: Sun, 13 Feb 2011 00:05:18 +0100 (CET)
> > Bug-Entry : http://bugzilla.kernel.org/show_bug.cgi?id=28052
> > Subject : [BUG] 2.6.38-rc2: Circular Locking Dependency
> > Submitter : Knut Petersen <Knut_Petersen@t-online.de>
> > Date : 2011-01-24 9:25 (20 days old)
> > Message-ID : <4D3D45A3.email@example.com>
> > References : http://marc.info/?l=linux-kernel&m=129586118515443&w=2
> Fixed by:
> commit 8d3bdbd55a7e2a3f2c148a4830aa26dd682b21c4
> Author: David S. Miller <firstname.lastname@example.org>
> Date: Tue Feb 8 15:02:50 2011 -0800
> net: Fix lockdep regression caused by initializing netdev queues too early.
> In commit aa9421041128abb4d269ee1dc502ff65fb3b7d69 ("net: init ingress
> queue") we moved the allocation and lock initialization of the queues
> into alloc_netdev_mq() since register_netdevice() is way too late.
> The problem is that dev->type is not setup until the setup()
> callback is invoked by alloc_netdev_mq(), and the dev->type is
> what determines the lockdep class to use for the locks in the
> Fix this by doing the queue allocation after the setup() callback
> This is safe because the setup() callback is not allowed to make any
> state changes that need to be undone on error (memory allocations,
> etc.). It may, however, make state changes that are undone by
> free_netdev() (such as netif_napi_add(), which is done by the
> ipoib driver's setup routine).
> The previous code also leaked a reference to the &init_net namespace
> object on RX/TX queue allocation failures.
> Signed-off-by: David S. Miller <email@example.com>