RE: [Intel-gfx] [PATCH 2/2] drm: share address space for dma bufs

[Ruhl, Michael J]

>-----Original Message-----
>From: Intel-gfx <intel-gfx-bounces@xxxxxxxxxxxxxxxxxxxxx> On Behalf Of Gerd
>Hoffmann
>Sent: Thursday, November 21, 2019 5:38 AM
>To: dri-devel@xxxxxxxxxxxxxxxxxxxxx
>Cc: David Airlie <airlied@xxxxxxxx>; intel-gfx@xxxxxxxxxxxxxxxxxxxxx; open list
><linux-kernel@xxxxxxxxxxxxxxx>; Maxime Ripard <mripard@xxxxxxxxxx>; Gerd
>Hoffmann <kraxel@xxxxxxxxxx>
>Subject: [Intel-gfx] [PATCH 2/2] drm: share address space for dma bufs
>
>Use the shared address space of the drm device (see drm_open() in
>drm_file.c) for dma-bufs too.  That removes a difference betweem drm
>device mmap vmas and dma-buf mmap vmas and fixes corner cases like
>unmaps not working properly.

Hi Gerd,

Just want to make sure I understand this...

So unmaps will not work correctly for mappings when a driver does a
drm_vma_node_unamp()?

I.e. the dmabuf mappings will not get cleaned up correctly?

This is a day one bug?

Thanks,

Mike


>Signed-off-by: Gerd Hoffmann <kraxel@xxxxxxxxxx>
>---
> drivers/gpu/drm/drm_prime.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
>diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
>index a9633bd241bb..c3fc341453c0 100644
>--- a/drivers/gpu/drm/drm_prime.c
>+++ b/drivers/gpu/drm/drm_prime.c
>@@ -240,6 +240,7 @@ void drm_prime_destroy_file_private(struct
>drm_prime_file_private *prime_fpriv)
> struct dma_buf *drm_gem_dmabuf_export(struct drm_device *dev,
> 				      struct dma_buf_export_info *exp_info)
> {
>+	struct drm_gem_object *obj = exp_info->priv;
> 	struct dma_buf *dma_buf;
>
> 	dma_buf = dma_buf_export(exp_info);
>@@ -247,7 +248,8 @@ struct dma_buf *drm_gem_dmabuf_export(struct
>drm_device *dev,
> 		return dma_buf;
>
> 	drm_dev_get(dev);
>-	drm_gem_object_get(exp_info->priv);
>+	drm_gem_object_get(obj);
>+	dma_buf->file->f_mapping = obj->dev->anon_inode->i_mapping;
>
> 	return dma_buf;
> }
>--
>2.18.1
>
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