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Date:   Fri, 19 Aug 2022 09:26:14 +0200
From:   Maxime Ripard <maxime@cerno.tech>
To:     Danilo Krummrich <dakr@redhat.com>
Cc:     daniel@ffwll.ch, airlied@linux.ie, tzimmermann@suse.de,
        dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH drm-misc-next 2/3] drm/vc4: plane: protect device
 resources after removal
Message-ID: <20220819072614.dthfuugbkk65o3ps@houat>
References: <20220819002905.82095-1-dakr@redhat.com>
 <20220819002905.82095-3-dakr@redhat.com>
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Hi,

On Fri, Aug 19, 2022 at 02:29:04AM +0200, Danilo Krummrich wrote:
> (Hardware) resources which are bound to the driver and device lifecycle
> must not be accessed after the device and driver are unbound.
>=20
> However, the DRM device isn't freed as long as the last user closed it,
> hence userspace can still call into the driver.
>=20
> Therefore protect the critical sections which are accessing those
> resources with drm_dev_enter() and drm_dev_exit().

Ah good catch, thanks

> Fixes: 9872c7a31921 ("drm/vc4: plane: Switch to drmm_universal_plane_allo=
c()")
> Signed-off-by: Danilo Krummrich <dakr@redhat.com>
> ---
>  drivers/gpu/drm/vc4/vc4_drv.h   |  1 +
>  drivers/gpu/drm/vc4/vc4_plane.c | 25 +++++++++++++++++++++++++
>  2 files changed, 26 insertions(+)
>=20
> diff --git a/drivers/gpu/drm/vc4/vc4_drv.h b/drivers/gpu/drm/vc4/vc4_drv.h
> index 418a8242691f..80da9a9337cc 100644
> --- a/drivers/gpu/drm/vc4/vc4_drv.h
> +++ b/drivers/gpu/drm/vc4/vc4_drv.h
> @@ -341,6 +341,7 @@ struct vc4_hvs {
> =20
>  struct vc4_plane {
>  	struct drm_plane base;
> +	struct drm_device *dev;

That pointer already exists in struct drm_plane

Looks good otherwise

Maxime

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