Re: [PATCH] kernfs: skip lockdep annotation always if ignore_lockdepis set

From: Tejun Heo
Date: Fri Feb 07 2014 - 14:53:24 EST

On Fri, Feb 07, 2014 at 09:47:01PM +0200, Imre Deak wrote:
> We skip lockdep annotations for sysfs attributes with ignore_lockdep
> set. An exception is kernfs_deactivate where we annotate even in this
> case. Since the lockdep map key needed for the annotation is not
> initialized whenever ignore_lockdep is set, we'll get a warning for
> the uninitialized key.
> Note that this happens since,
> commit 517e64f57883bd63c5a4ab8b3d0d3ed68c55d0cf
> Author: Tejun Heo <tj@xxxxxxxxxx>
> Date: Thu Nov 28 14:54:29 2013 -0500
> Before this change we had a valid key even in case of ignore_lockdep, so
> the annotation in kernfs_deactivate worked, or at least didn't produce
> the above warning. Fix this by skipping the annotation whenever
> ignore_lockdep is set.
> The actual attribute triggering the bug was 'delete_device' in
> drivers/i2c/i2c-core.c, for the backtrace see the reference below.

I think Greg already has about the same patch queued.


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