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Revert "drm/amdgpu: Use dma_buf from GEM object instance"

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This reverts commit 515986100d.

The dma_buf field in struct drm_gem_object is not stable over the
object instance's lifetime. The field becomes NULL when user space
releases the final GEM handle on the buffer object. This resulted
in a NULL-pointer deref.

Workarounds in commit 5307dce878 ("drm/gem: Acquire references on
GEM handles for framebuffers") and commit f6bfc9afc7 ("drm/framebuffer:
Acquire internal references on GEM handles") only solved the problem
partially. They especially don't work for buffer objects without a DRM
framebuffer associated.

Hence, this revert to going back to using .import_attach->dmabuf.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Simona Vetter <simona.vetter@ffwll.ch>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Link: https://lore.kernel.org/r/20250715082635.34974-1-tzimmermann@suse.de
This commit is contained in:
Thomas Zimmermann
2025-07-15 10:26:22 +02:00
parent 9af8f2b469
commit 3eb61d7cb7
3 changed files with 4 additions and 3 deletions
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2
drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
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@@ -514,7 +514,7 @@ bool amdgpu_dmabuf_is_xgmi_accessible(struct amdgpu_device *adev,
return false;
if (drm_gem_is_imported(obj)) {
struct dma_buf *dma_buf = obj->dma_buf;
struct dma_buf *dma_buf = obj->import_attach->dmabuf;
if (dma_buf->ops != &amdgpu_dmabuf_ops)
/* No XGMI with non AMD GPUs */