| Message ID | ZsZLFS1CsHkKjw+C@elsanto (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [next] drm/nouveau: Avoid -Wflex-array-member-not-at-end warning | expand |
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@kernel.org> > --- > 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); (Maybe a helper is needed for that?) #define STACK_FLEX_COUNT(name, member) \ ((sizeof(name##_u) = sizeof(*(name))) / sizeof(*(name)->member)) > @@ -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@kernel.org>
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@kernel.org> >> --- >> 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@kernel.org> > Thanks! -- Gustavo
Hi all, Friendly ping: who can take this, please?
Hi, On 9/13/24 10:09 AM, Gustavo A. R. Silva wrote: > Hi all, > > Friendly ping: who can take this, please?
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. */ u32 max_ac_packet; - struct { - struct nvif_outp_infoframe_v0 infoframe; - u8 data[17]; - } args = { 0 }; int ret, size; max_ac_packet = mode->htotal - mode->hdisplay; @@ -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; if (!drm_hdmi_avi_infoframe_from_display_mode(&infoframe.avi, &nv_connector->base, mode)) { drm_hdmi_avi_infoframe_quant_range(&infoframe.avi, &nv_connector->base, mode, HDMI_QUANTIZATION_RANGE_FULL); - size = hdmi_infoframe_pack(&infoframe, args.data, ARRAY_SIZE(args.data)); + size = hdmi_infoframe_pack(&infoframe, args->data, data_len); } else { size = 0; } - nvif_outp_infoframe(&nv_encoder->outp, NVIF_OUTP_INFOFRAME_V0_AVI, &args.infoframe, size); + nvif_outp_infoframe(&nv_encoder->outp, NVIF_OUTP_INFOFRAME_V0_AVI, args, size); /* Vendor InfoFrame. */ - memset(&args.data, 0, sizeof(args.data)); + memset(args->data, 0, data_len); if (!drm_hdmi_vendor_infoframe_from_display_mode(&infoframe.vendor.hdmi, &nv_connector->base, mode)) - size = hdmi_infoframe_pack(&infoframe, args.data, ARRAY_SIZE(args.data)); + size = hdmi_infoframe_pack(&infoframe, args->data, data_len); else size = 0; - nvif_outp_infoframe(&nv_encoder->outp, NVIF_OUTP_INFOFRAME_V0_VSI, &args.infoframe, size); + nvif_outp_infoframe(&nv_encoder->outp, NVIF_OUTP_INFOFRAME_V0_VSI, args, size); nv_encoder->hdmi.enabled = true; }
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@kernel.org> --- drivers/gpu/drm/nouveau/dispnv50/disp.c | 20 +++++++++----------- 1 file changed, 9 insertions(+), 11 deletions(-)