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drm/prime: Take a ref on the drm_dev when exporting a dma_buf

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dma_buf may live a long time, longer than the last direct user of the
driver. We already hold a reference to the owner module (that prevents
the object code from disappearing), but there is no reference to the
drm_dev - so the pointers to the driver backend themselves may vanish.

v2: Resist temptation to fix the bug in armada_gem.c not setting the
correct flags on the exported dma-buf (it should pass the flags through
and not be arbitrarily setting O_RDWR).

Use a common wrapper for exporting the dmabuf and acquiring the
reference to the drm_device.

Testcase: igt/vgem_basic/unload
Suggested-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Petri Latvala <petri.latvala@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: stable@vger.kernel.org
Tested-by: Petri Latvala <petri.latvala@intel.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20161005122145.1507-2-chris@chris-wilson.co.uk
This commit is contained in:
Chris Wilson
2016-10-05 13:21:44 +01:00
committed by Daniel Vetter
parent 56a76c0123
commit a4fce9cb78
6 changed files with 37 additions and 5 deletions
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30
drivers/gpu/drm/drm_prime.c
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@@ -283,19 +283,47 @@ static void drm_gem_unmap_dma_buf(struct dma_buf_attachment *attach,
/* nothing to be done here */
}
/**
* drm_gem_dmabuf_export - dma_buf export implementation for GEM
* @dma_buf: buffer to be exported
*
* This wraps dma_buf_export() for use by generic GEM drivers that are using
* drm_gem_dmabuf_release(). In addition to calling dma_buf_export(), we take
* a reference to the drm_device which is released by drm_gem_dmabuf_release().
*
* Returns the new dmabuf.
*/
struct dma_buf *drm_gem_dmabuf_export(struct drm_device *dev,
struct dma_buf_export_info *exp_info)
{
struct dma_buf *dma_buf;
dma_buf = dma_buf_export(exp_info);
if (!IS_ERR(dma_buf))
drm_dev_ref(dev);
return dma_buf;
}
EXPORT_SYMBOL(drm_gem_dmabuf_export);
/**
* drm_gem_dmabuf_release - dma_buf release implementation for GEM
* @dma_buf: buffer to be released
*
* Generic release function for dma_bufs exported as PRIME buffers. GEM drivers
* must use this in their dma_buf ops structure as the release callback.
* drm_gem_dmabuf_release() should be used in conjunction with
* drm_gem_dmabuf_export().
*/
void drm_gem_dmabuf_release(struct dma_buf *dma_buf)
{
struct drm_gem_object *obj = dma_buf->priv;
struct drm_device *dev = obj->dev;
/* drop the reference on the export fd holds */
drm_gem_object_unreference_unlocked(obj);
drm_dev_unref(dev);
}
EXPORT_SYMBOL(drm_gem_dmabuf_release);
@@ -412,7 +440,7 @@ struct dma_buf *drm_gem_prime_export(struct drm_device *dev,
if (dev->driver->gem_prime_res_obj)
exp_info.resv = dev->driver->gem_prime_res_obj(obj);
return dma_buf_export(&exp_info);
return drm_gem_dmabuf_export(dev, &exp_info);
}
EXPORT_SYMBOL(drm_gem_prime_export);