Re: [PATCH v3 1/2] drm/gem: drm_gem_dumb_map_offset(): reject dma-buf

From: Brian Starkey <brian.starkey@arm.com>
To: Noralf Tr??nnes <noralf@tronnes.org>
Cc: narmstrong@baylibre.com, daniel.vetter@ffwll.ch,
	liviu.dudau@arm.com, dri-devel@lists.freedesktop.org,
	thierry.reding@gmail.com, laurent.pinchart@ideasonboard.com,
	daniel.vetter@intel.com, marex@denx.de,
	boris.brezillon@free-electrons.com, abrodkin@synopsys.com,
	linux@armlinux.org.uk, z.liuxinliang@hisilicon.com,
	kong.kongxinwei@hisilicon.com, tomi.valkeinen@ti.com,
	airlied@redhat.com, puck.chen@hisilicon.com, jsarha@ti.com,
	vincent.abriou@st.com, alison.wang@freescale.com,
	sw0312.kim@samsung.com, philippe.cornu@st.com,
	yannick.fertre@st.com, kyungmin.park@samsung.com,
	zourongrong@gmail.com, maxime.ripard@free-electrons.com,
	shawnguo@kernel.org, kraxel@redhat.com
Subject: Re: [PATCH v3 1/2] drm/gem: drm_gem_dumb_map_offset(): reject dma-buf
Date: Thu, 24 Aug 2017 11:04:01 +0100	[thread overview]
Message-ID: <20170824100400.GA25152@e107564-lin.cambridge.arm.com> (raw)
In-Reply-To: <1de97ff3-44d5-aeac-e03d-4976e455ab67@tronnes.org>

Hi,

Thanks for the CC.

On Fri, Aug 18, 2017 at 06:13:14PM +0200, Noralf Tr??nnes wrote:
>(cc affected parties)
>
>
>Den 18.08.2017 09.46, skrev Daniel Vetter:
>>On Thu, Aug 17, 2017 at 06:21:30PM +0200, Noralf Tr??nnes wrote:
>>>Reject mapping an imported dma-buf since is's an invalid use-case.
>>>
>>>Cc: Philipp Zabel <p.zabel@pengutronix.de>
>>>Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
>>>Cc: Sean Paul <seanpaul@chromium.org>
>>>Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
>>>Signed-off-by: Noralf Tr??nnes <noralf@tronnes.org>
>>I think acks from someone using mali would be good too. amdgpu already has
>>such checks, so I think on the desktop side we're ok.
>>

This looks like it would break anyone running the Mali-4xx series GPUs
with the Arm graphics stack (e.g. Hikey board).

I don't know where that sits in terms of policy.

Cheers,
-Brian

>>Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
>>
>>But I think this one here definitely needs a few more acks. I could break
>>uabi if we're unlucky, so let's not rush it.
>
>Ok, I've CC'ed the affected parties to increase the odds that they look
>at this. These are the drivers using drm_gem_dumb_map_offset()
>(hopefully I got the list right):
>
>arc
>atmel-hlcdc
>cirrus
>exynos
>fsl-dcu
>gma500
>hdlcd
>imx
>kirin
>mali-dp
>mediatek
>meson
>mxsfb
>pl111
>rcar-du
>rockchip
>shmobile
>sti
>stm
>sun4i
>tegra
>tilcd
>vc4
>zte
>
>
>Noralf.
>
>>-Daniel
>>
>>>---
>>>  drivers/gpu/drm/drm_gem.c | 6 ++++++
>>>  1 file changed, 6 insertions(+)
>>>
>>>diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
>>>index ad4e9cf..8da5801 100644
>>>--- a/drivers/gpu/drm/drm_gem.c
>>>+++ b/drivers/gpu/drm/drm_gem.c
>>>@@ -333,6 +333,12 @@ int drm_gem_dumb_map_offset(struct drm_file *file, struct drm_device *dev,
>>>  	if (!obj)
>>>  		return -ENOENT;
>>>+	/* Don't allow imported objects to be mapped */
>>>+	if (obj->import_attach) {
>>>+		ret = -EINVAL;
>>>+		goto out;
>>>+	}
>>>+
>>>  	ret = drm_gem_create_mmap_offset(obj);
>>>  	if (ret)
>>>  		goto out;
>>>-- 
>>>2.7.4
>>>
>
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