| Message ID | 20171107191348.17555-7-noralf@tronnes.org |
|---|---|
| State | Accepted |
| Commit | 8d25ccebef55b8fc47b674f24ccdccbef08e2f32 |
| Headers | show |
| Series |
"drm/framebuffer: Add framebuffer debugfs file"
( rev:
5
)
in
DRI devel |
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 \
Hi Noralf, Thank you for the patch. On Tuesday, 7 November 2017 21:13:42 EET Noralf Trønnes wrote: > 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@ideasonboard.com> > Signed-off-by: Noralf Trønnes <noralf@tronnes.org> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> > --- > 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 \
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@ideasonboard.com> Signed-off-by: Noralf Trønnes <noralf@tronnes.org> --- include/drm/drm_gem_cma_helper.h | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-)