This allows the argument to be a const.
The other option was to keep it an inline function and make the argument
a const:
static inline struct drm_gem_cma_object *
to_drm_gem_cma_obj(const struct drm_gem_object *gem_obj)
{
return container_of(gem_obj, struct drm_gem_cma_object, base);
}
This will happily return a non-const pointer to the drm_gem_cma_object
based on a const pointer to the contained drm_gem_object, thus creating
const-safety problems.
There was an attempt to fix the problem in the container_of() macro
itself (see https://lkml.org/lkml/2017/5/19/381) but the patch seems to
have fallen through the cracks. It would require turning this inline
function into a macro.
By making this a macro now, we will benefit from a possible future
enhancement of container_of(). We don't loose type checking by doing
this, container_of() takes care of that.
Suggested-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
Signed-off-by: Noralf Trønnes <noralf@xxxxxxxxxxx>
---
include/drm/drm_gem_cma_helper.h | 7 ++-----
1 file changed, 2 insertions(+), 5 deletions(-)
diff --git a/include/drm/drm_gem_cma_helper.h b/include/drm/drm_gem_cma_helper.h
index 58a739bf15f1..7a3dcf0cf289 100644
--- a/include/drm/drm_gem_cma_helper.h
+++ b/include/drm/drm_gem_cma_helper.h
@@ -20,11 +20,8 @@ struct drm_gem_cma_object {
void *vaddr;
};
-static inline struct drm_gem_cma_object *
-to_drm_gem_cma_obj(struct drm_gem_object *gem_obj)
-{
- return container_of(gem_obj, struct drm_gem_cma_object, base);
-}
+#define to_drm_gem_cma_obj(gem_obj) \
+ container_of(gem_obj, struct drm_gem_cma_object, base)
#ifndef CONFIG_MMU
#define DRM_GEM_CMA_UNMAPPED_AREA_FOPS \
--
2.14.2
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