Commit 16fdb3cc authored by Thomas Zimmermann's avatar Thomas Zimmermann
Browse files

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



This reverts commit 482c7e29.

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 5307dce8 ("drm/gem: Acquire references on
GEM handles for framebuffers") and commit f6bfc9af ("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: default avatarThomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: default avatarSimona Vetter <simona.vetter@ffwll.ch>
Link: https://lore.kernel.org/r/20250715084549.41473-1-tzimmermann@suse.de
parent e228e7d3

drivers/gpu/drm/tegra/gem.c

+1 −1
Original line number Diff line number Diff line
@@ -526,7 +526,7 @@ void tegra_bo_free_object(struct drm_gem_object *gem) 
		if (drm_gem_is_imported(gem)) {

			dma_buf_unmap_attachment_unlocked(gem->import_attach, bo->sgt,

							  DMA_TO_DEVICE);

			dma_buf_detach(gem->dma_buf, gem->import_attach);

			dma_buf_detach(gem->import_attach->dmabuf, gem->import_attach);

		}

	}