linux-kernel - Re: [PATCH 05/12] drm/i915: Protect lockdep functions with #ifdef

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Date:   Wed, 9 Feb 2022 11:27:03 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Jani Nikula <jani.nikula@...ux.intel.com>
Cc:     Namhyung Kim <namhyung@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>, Will Deacon <will@...nel.org>,
        Waiman Long <longman@...hat.com>,
        Boqun Feng <boqun.feng@...il.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Byungchul Park <byungchul.park@....com>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Radoslaw Burny <rburny@...gle.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>,
        intel-gfx@...ts.freedesktop.org, paulmck@...nel.org
Subject: Re: [PATCH 05/12] drm/i915: Protect lockdep functions with #ifdef

On Wed, 09 Feb 2022 15:49:01 +0200
Jani Nikula <jani.nikula@...ux.intel.com> wrote:

> > Because I want to use the lockdep annotation for other purposes.
> > But the workqueue lockdep_map was defined under LOCKDEP
> > only.  Please see the description in the cover letter.
> >
> > https://lore.kernel.org/all/20220208184208.79303-1-namhyung@kernel.org/  
> 
> So lockdep_init_map() might still be there and build just fine for
> CONFIG_LOCKDEP=n, but now we're actually required to wrap all call sites
> in #ifdefs depending on the purpose? I'm not convinced yet.

I addressed this already. I suggested to add a "raw" variant that turns to
a nop when LOCKDEP is not enabled. That is, for those locations that are
only for working with LOCKDEP, the call will be:

	lockdep_init_map_raw()

This will differentiate the locations that are for just lockdep and those
that are for both lockdep and tracing.

-- Steve