linux-kernel - Re: [tip:core/locking] lockdep, bug: Exclude TAINT_FIRMWARE

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Message-ID: <1323186215.7454.271.camel@deadeye>
Date:	Tue, 06 Dec 2011 15:43:35 +0000
From:	Ben Hutchings <ben@...adent.org.uk>
To:	Alan Cox <alan@...rguk.ukuu.org.uk>
Cc:	Nick Bowler <nbowler@...iptictech.com>, mingo@...hat.com,
	hpa@...or.com, linux-kernel@...r.kernel.org,
	a.p.zijlstra@...llo.nl, tglx@...utronix.de, mingo@...e.hu,
	linux-tip-commits@...r.kernel.org
Subject: Re: [tip:core/locking] lockdep, bug: Exclude
 TAINT_FIRMWARE_WORKAROUND from disabling lockdep

On Tue, 2011-12-06 at 15:42 +0000, Alan Cox wrote:
> On Tue, 6 Dec 2011 10:13:45 -0500
> Nick Bowler <nbowler@...iptictech.com> wrote:
> 
> > On 2011-12-06 01:38 -0800, tip-bot for Peter Zijlstra wrote:
> > > Commit-ID:  df754e6af2f237a6c020c0daff55a1a609338e31
> > > Gitweb:     http://git.kernel.org/tip/df754e6af2f237a6c020c0daff55a1a609338e31
> > > Author:     Peter Zijlstra <a.p.zijlstra@...llo.nl>
> > > AuthorDate: Mon, 14 Nov 2011 13:13:49 +0100
> > > Committer:  Ingo Molnar <mingo@...e.hu>
> > > CommitDate: Tue, 6 Dec 2011 08:16:47 +0100
> > > 
> > > lockdep, bug: Exclude TAINT_FIRMWARE_WORKAROUND from disabling lockdep
> > > 
> > > It's unlikely that TAINT_FIRMWARE_WORKAROUND causes false
> > > lockdep messages, so do not disable lockdep in that case.
> > > We still want to keep lockdep disabled in the
> > > TAINT_OOT_MODULE case:
> > > 
> > >   - bin-only modules can cause various instabilities in
> > >     their and in unrelated kernel code
> > > 
> > >   - they are impossible to debug for kernel developers
> > > 
> > >   - they also typically do not have the copyright license
> > >     permission to link to the GPL-ed lockdep code.
> > 
> > This is all bogus.  We have a proprietary module taint for the above.
> > Out of tree does not mean "bin-only", "non-GPL" or anything else like
> > that.  
> 
> It also stops people developing drivers of their own who are not
> building them in the kernel tree currently (eg when I'm building tests
> of the GMA500 graphics driver). This is a ludicrous patch and should be
> reverted

My change to set TAINT_OOT_MODULE had the (unintentional) effect of
disabling lockdep for OOT modules.  I subsequently proposed to change
that (while adding taint flags to lockdep output).  This patch doesn't
make any change either way.

Ben.

-- 
Ben Hutchings
Absolutum obsoletum. (If it works, it's out of date.) - Stafford Beer

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