linux-kernel - Re: [PATCH 13/26] locking: Add non-fatal spin lock assert

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Date:	Thu, 4 Sep 2014 07:14:11 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Peter Hurley <peter@...leysoftware.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jslaby@...e.cz>,
	One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>,
	linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 13/26] locking: Add non-fatal spin lock assert


* Peter Zijlstra <peterz@...radead.org> wrote:

> On Wed, Sep 03, 2014 at 10:50:01AM -0400, Peter Hurley wrote:
> > So a lockdep-only assert is unlikely to draw attention to existing bugs,
> > especially in established drivers.
> 
> By the same logic lockdep will not find locking errors in established
> drivers.

Indeed, this patch is ill-advised in several ways:

  - it extends an API variant that we want to phase

  - emits a warning even if say lockdep has already emitted a
    warning and locking state is not guaranteed to be consistent. 

  - makes the kernel more expensive once fully debugged, in that
    non-fatal checks are unconditional.

Also please submit locking related patches as standalone series 
to the locking subsystem, not embedded in an unrelated series.

Thanks,

	Ingo
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