On 22/08/24 11:27, Kees Cook wrote:
On Wed, Aug 21, 2024 at 02:16:21PM -0600, Gustavo A. R. Silva wrote:
Use the `DEFINE_RAW_FLEX()` helper for an on-stack definition of
a flexible structure where the size of the flexible-array member
is known at compile-time, and refactor the rest of the code,
accordingly.
So, with this, fix the following warning:
drivers/gpu/drm/nouveau/dispnv50/disp.c:779:47: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
Signed-off-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx>
---
drivers/gpu/drm/nouveau/dispnv50/disp.c | 20 +++++++++-----------
1 file changed, 9 insertions(+), 11 deletions(-)
diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c b/drivers/gpu/drm/nouveau/dispnv50/disp.c
index eed579a6c858..ddddc69640be 100644
--- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
+++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
@@ -774,11 +774,9 @@ nv50_hdmi_enable(struct drm_encoder *encoder, struct nouveau_crtc *nv_crtc,
struct drm_hdmi_info *hdmi = &nv_connector->base.display_info.hdmi;
union hdmi_infoframe infoframe = { 0 };
const u8 rekey = 56; /* binary driver, and tegra, constant */
+ DEFINE_RAW_FLEX(struct nvif_outp_infoframe_v0, args, data, 17);
+ const u8 data_len = 17; /* same length as in DEFINE_RAW_FLEX above. */
To avoid repeating the open-coded "17", this could either be a define:
nv50_hdmi_enable(...)
{
...
#define data_len 17
DEFINE_RAW_FLEX(struct nvif_outp_infoframe_v0, args, data, data_len);
...rest of function...
#undef data_len
}
or an ungainly but compile-time calculated value that exposes some
DEFINE_FLEX internals:
const u8 data_len = (sizeof(args_u) - sizeof(*args)) / sizeof(*args->data);
Yeah, I actually thought of something more like just __struct_size(args) - sizeof(*args),
as the flex array member is `__u8 data[]`.
(Maybe a helper is needed for that?)
#define STACK_FLEX_COUNT(name, member) \
((sizeof(name##_u) = sizeof(*(name))) / sizeof(*(name)->member))
I don't like this `sizeof(name##_u)` part as it is detached from the DEFINE_RAW_FLEX()
internals. Probably use `__struct_size(args)` instead, as in the example above.
@@ -815,29 +813,29 @@ nv50_hdmi_enable(struct drm_encoder *encoder, struct nouveau_crtc *nv_crtc,
return;
/* AVI InfoFrame. */
- args.infoframe.version = 0;
- args.infoframe.head = nv_crtc->index;
+ args->version = 0;
+ args->head = nv_crtc->index;
The stack variable (was before and is again) already zero-initialized,
so the "= 0" line shouldn't be needed.
But neither of these comments are show-stoppers, IMO.
Reviewed-by: Kees Cook <kees@xxxxxxxxxx>
Thanks!
--
Gustavo
