drm/nouveau: disp: Use __member_size() helper

Use __member_size() to get the size of the flex-array member at compile
time, instead of the convoluted expression `__struct_size(p) - sizeof(*p)`

Link: https://lore.kernel.org/r/aAe5eNDnRyGnxLMX@kspp
Reviewed-by: Kees Cook <kees@kernel.org>
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Danilo Krummrich <dakr@kernel.org>

diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c b/drivers/gpu/drm/nouveau/dispnv50/disp.c
index 725331638a15d95f73d94cc24a358db01510e077..9bed728cb00e4a588ccc3a9003531e3081ea3968 100644 (file)
--- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
+++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
@@ -776,7 +776,7 @@ nv50_hdmi_enable(struct drm_encoder *encoder, struct nouveau_crtc *nv_crtc,
        const u8 rekey = 56; /* binary driver, and tegra, constant */
        u32 max_ac_packet;
        DEFINE_RAW_FLEX(struct nvif_outp_infoframe_v0, args, data, 17);
-       const u8 data_len = __struct_size(args) - sizeof(*args);
+       const u8 data_len = __member_size(args->data);
        int ret, size;
 
        max_ac_packet  = mode->htotal - mode->hdisplay;