[PATCH 6.12 626/626] drm/gem: Internally test import_attach for imported objects

[Greg Kroah-Hartman]

6.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Thomas Zimmermann <tzimmermann at suse.de>

commit 8260731ccad0451207b45844bb66eb161a209218 upstream.

Test struct drm_gem_object.import_attach to detect imported objects.

During object clenanup, the dma_buf field might be NULL. Testing it in
an object's free callback then incorrectly does a cleanup as for native
objects. Happens for calls to drm_mode_destroy_dumb_ioctl() that
clears the dma_buf field in drm_gem_object_exported_dma_buf_free().

v3:
- only test for import_attach (Boris)
v2:
- use import_attach.dmabuf instead of dma_buf (Christian)

Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
Fixes: b57aa47d39e9 ("drm/gem: Test for imported GEM buffers with helper")
Reported-by: Andy Yan <andyshrk at 163.com>
Closes: https://lore.kernel.org/dri-devel/38d09d34.4354.196379aa560.Coremail.andyshrk@163.com/
Tested-by: Andy Yan <andyshrk at 163.com>
Cc: Thomas Zimmermann <tzimmermann at suse.de>
Cc: Anusha Srivatsa <asrivats at redhat.com>
Cc: Christian König <christian.koenig at amd.com>
Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Cc: Maxime Ripard <mripard at kernel.org>
Cc: David Airlie <airlied at gmail.com>
Cc: Simona Vetter <simona at ffwll.ch>
Cc: Sumit Semwal <sumit.semwal at linaro.org>
Cc: "Christian König" <christian.koenig at amd.com>
Cc: dri-devel at lists.freedesktop.org
Cc: linux-media at vger.kernel.org
Cc: linaro-mm-sig at lists.linaro.org
Reviewed-by: Boris Brezillon <boris.brezillon at collabora.com>
Reviewed-by: Simona Vetter <simona.vetter at ffwll.ch>
Link: https://lore.kernel.org/r/20250416065820.26076-1-tzimmermann@suse.de
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
---
 include/drm/drm_gem.h |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/include/drm/drm_gem.h
+++ b/include/drm/drm_gem.h
@@ -580,8 +580,7 @@ static inline bool drm_gem_object_is_sha
  */
 static inline bool drm_gem_is_imported(const struct drm_gem_object *obj)
 {
-	/* The dma-buf's priv field points to the original GEM object. */
-	return obj->dma_buf && (obj->dma_buf->priv != obj);
+	return !!obj->import_attach;
 }
 
 #ifdef CONFIG_LOCKDEP