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

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Date:   Tue, 08 Feb 2022 20:51:38 +0200
From:   Jani Nikula <jani.nikula@...ux.intel.com>
To:     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>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Steven Rostedt <rostedt@...dmis.org>,
        Byungchul Park <byungchul.park@....com>,
        "Paul E. McKenney" <paul.mckenney@...aro.org>,
        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
Subject: Re: [PATCH 05/12] drm/i915: Protect lockdep functions with #ifdef

On Tue, 08 Feb 2022, Namhyung Kim <namhyung@...nel.org> wrote:
> With upcoming lock tracepoints config, it'd define some of lockdep
> functions without enabling CONFIG_LOCKDEP actually.  The existing code
> assumes those functions will be removed by the preprocessor but it's
> not the case anymore.  Let's protect the code with #ifdef's explicitly.

I don't understand why you can't keep the no-op stubs for
CONFIG_LOCKDEP=n.

BR,
Jani.

>
> Cc: Jani Nikula <jani.nikula@...ux.intel.com>
> Cc: Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>
> Cc: Rodrigo Vivi <rodrigo.vivi@...el.com>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>
> Cc: intel-gfx@...ts.freedesktop.org
> Signed-off-by: Namhyung Kim <namhyung@...nel.org>
> ---
>  drivers/gpu/drm/i915/intel_wakeref.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/intel_wakeref.c b/drivers/gpu/drm/i915/intel_wakeref.c
> index dfd87d082218..6e4b8d036283 100644
> --- a/drivers/gpu/drm/i915/intel_wakeref.c
> +++ b/drivers/gpu/drm/i915/intel_wakeref.c
> @@ -106,8 +106,11 @@ void __intel_wakeref_init(struct intel_wakeref *wf,
>  	wf->wakeref = 0;
>  
>  	INIT_DELAYED_WORK(&wf->work, __intel_wakeref_put_work);
> +
> +#ifdef CONFIG_LOCKDEP
>  	lockdep_init_map(&wf->work.work.lockdep_map,
>  			 "wakeref.work", &key->work, 0);
> +#endif
>  }
>  
>  int intel_wakeref_wait_for_idle(struct intel_wakeref *wf)

-- 
Jani Nikula, Intel Open Source Graphics Center