Feedback-ID: i8771445c:Fastmail
Date:   Tue, 21 Feb 2023 12:38:34 +0100
From:   Maxime Ripard <maxime@cerno.tech>
To:     Hans Verkuil <hverkuil@xs4all.nl>
Cc:     Emma Anholt <emma@anholt.net>, David Airlie <airlied@gmail.com>,
        Daniel Vetter <daniel@ffwll.ch>,
        dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
        Dave Stevenson <dave.stevenson@raspberrypi.com>,
        Thomas Zimmermann <tzimmermann@suse.de>
Subject: Re: [PATCH v2 1/9] drm/vc4: Switch to container_of_const
Message-ID: <20230221113834.i3nitxp4soev6cks@houat>
References: <20221207-rpi-hdmi-improvements-v2-0-8ace2d8221ad@cerno.tech>
 <20221207-rpi-hdmi-improvements-v2-1-8ace2d8221ad@cerno.tech>
 <c70e40fe-6834-2382-ec89-28714a67fd1f@xs4all.nl>
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Hi Hans,

On Sat, Feb 18, 2023 at 11:45:04AM +0100, Hans Verkuil wrote:
> > diff --git a/drivers/gpu/drm/vc4/vc4_bo.c b/drivers/gpu/drm/vc4/vc4_bo.c
> > index 86d629e45307..d0a00ed42cb0 100644
> > --- a/drivers/gpu/drm/vc4/vc4_bo.c
> > +++ b/drivers/gpu/drm/vc4/vc4_bo.c
> > @@ -609,7 +609,7 @@ static void vc4_free_object(struct drm_gem_object *=
gem_bo)
> >  static void vc4_bo_cache_time_work(struct work_struct *work)
> >  {
> >  	struct vc4_dev *vc4 =3D
> > -		container_of(work, struct vc4_dev, bo_cache.time_work);
> > +		container_of_const(work, struct vc4_dev, bo_cache.time_work);
>=20
> ...I think this is misleading. It's definitely not const, so switching to
> container_of_const suggests that there is some 'constness' involved, which
> isn't the case. I'd leave this just as 'container_of'. This also reduces =
the
> size of the patch, since this is done in quite a few places.

The name threw me off too, but it's supposed to keep the argument
pointer constness, not always take and return a const pointer. I still
believe that it's beneficial since, if the work pointer was ever to
change constness, we would have that additional check.

Maxime