[PATCH] drm: Take ownership of the dmabuf->obj when exporting

[PATCH] drm: Take ownership of the dmabuf->obj when exporting

[Chris Wilson]

Currently the reference for the dmabuf->obj is incremented for the
dmabuf in drm_gem_prime_handle_to_fd() (at the high level userspace
interface), but is released in drm_gem_dmabuf_release() (the lowlevel
handler). Improve the symmetry of the dmabuf->obj ownership by acquiring
the reference in drm_gem_dmabuf_export(). This makes it easier to use
the prime functions directly.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 drivers/gpu/drm/drm_prime.c       | 9 +++++----
 drivers/gpu/drm/vgem/vgem_fence.c | 1 -
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
index b22a94dd7b53..5ef946d5a32d 100644
--- a/drivers/gpu/drm/drm_prime.c
+++ b/drivers/gpu/drm/drm_prime.c
@@ -300,8 +300,11 @@ struct dma_buf *drm_gem_dmabuf_export(struct drm_device *dev,
 	struct dma_buf *dma_buf;
 
 	dma_buf = dma_buf_export(exp_info);
-	if (!IS_ERR(dma_buf))
-		drm_dev_ref(dev);
+	if (IS_ERR(dma_buf))
+		return dma_buf;
+
+	drm_dev_ref(dev);
+	drm_gem_object_reference(exp_info->priv);
 
 	return dma_buf;
 }
@@ -472,8 +475,6 @@ static struct dma_buf *export_and_register_object(struct drm_device *dev,
 	 */
 	obj->dma_buf = dmabuf;
 	get_dma_buf(obj->dma_buf);
-	/* Grab a new ref since the callers is now used by the dma-buf */
-	drm_gem_object_reference(obj);
 
 	return dmabuf;
 }
diff --git a/drivers/gpu/drm/vgem/vgem_fence.c b/drivers/gpu/drm/vgem/vgem_fence.c
index 9cb00a5d5d08..da25dfe7b80e 100644
--- a/drivers/gpu/drm/vgem/vgem_fence.c
+++ b/drivers/gpu/drm/vgem/vgem_fence.c
@@ -126,7 +126,6 @@ static int attach_dmabuf(struct drm_device *dev,
 		return PTR_ERR(dmabuf);
 
 	obj->dma_buf = dmabuf;
-	drm_gem_object_reference(obj);
 	return 0;
 }
 
-- 
2.11.0

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Re: [Intel-gfx] [PATCH] drm: Take ownership of the dmabuf->obj when exporting

[Joonas Lahtinen]

On ke, 2016-12-07 at 21:45 +0000, Chris Wilson wrote:
> Currently the reference for the dmabuf->obj is incremented for the
> dmabuf in drm_gem_prime_handle_to_fd() (at the high level userspace
> interface), but is released in drm_gem_dmabuf_release() (the lowlevel
> handler). Improve the symmetry of the dmabuf->obj ownership by acquiring
> the reference in drm_gem_dmabuf_export(). This makes it easier to use
> the prime functions directly.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>

Regards, Joonas
-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation
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Re: [PATCH] drm: Take ownership of the dmabuf->obj when exporting

[Daniel Vetter]

On Thu, Dec 08, 2016 at 03:03:29PM +0200, Joonas Lahtinen wrote:
> On ke, 2016-12-07 at 21:45 +0000, Chris Wilson wrote:
> > Currently the reference for the dmabuf->obj is incremented for the
> > dmabuf in drm_gem_prime_handle_to_fd() (at the high level userspace
> > interface), but is released in drm_gem_dmabuf_release() (the lowlevel
> > handler). Improve the symmetry of the dmabuf->obj ownership by acquiring
> > the reference in drm_gem_dmabuf_export(). This makes it easier to use
> > the prime functions directly.
> > 
> > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> 
> Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>

Sorry forgot to reply here that I merged this, after some discussion with
Chris on irc to make sure the kerneldoc is updated.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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