| Message ID | Z-a2DAQmcsHHlyci@kspp (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [next] drm/nouveau/outp: Avoid -Wflex-array-member-not-at-end warning | expand |
On Fri, Mar 28, 2025 at 08:45:32AM -0600, Gustavo A. R. Silva wrote: > -Wflex-array-member-not-at-end was introduced in GCC-14, and we are > getting ready to enable it, globally. > > 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 these changes, fix the following warning: > > drivers/gpu/drm/nouveau/nvif/outp.c:199:45: 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/nvif/outp.c | 16 +++++++--------- > 1 file changed, 7 insertions(+), 9 deletions(-) > > diff --git a/drivers/gpu/drm/nouveau/nvif/outp.c b/drivers/gpu/drm/nouveau/nvif/outp.c > index 6daeb7f0b09b..403cf16d5e84 100644 > --- a/drivers/gpu/drm/nouveau/nvif/outp.c > +++ b/drivers/gpu/drm/nouveau/nvif/outp.c > @@ -195,20 +195,18 @@ nvif_outp_dp_aux_pwr(struct nvif_outp *outp, bool enable) > int > nvif_outp_hda_eld(struct nvif_outp *outp, int head, void *data, u32 size) > { > - struct { > - struct nvif_outp_hda_eld_v0 mthd; > - u8 data[128]; > - } args; > + DEFINE_RAW_FLEX(struct nvif_outp_hda_eld_v0, mthd, data, 128); > int ret; > > - if (WARN_ON(size > ARRAY_SIZE(args.data))) > + if (WARN_ON(size > 128)) Seems a bit unfortunate that the size is duplicated here. Can we have an accessor macro to derive the size for us? union { u8 bytes[struct_size_t(type, member, count)]; type obj; } name##_u initializer; Maybe a macro that returns the size difference between bytes and obj? > return -EINVAL; > > - args.mthd.version = 0; > - args.mthd.head = head; > + mthd->version = 0; > + mthd->head = head; > > - memcpy(args.data, data, size); > - ret = nvif_mthd(&outp->object, NVIF_OUTP_V0_HDA_ELD, &args, sizeof(args.mthd) + size); > + memcpy(mthd->data, data, size); > + ret = nvif_mthd(&outp->object, NVIF_OUTP_V0_HDA_ELD, mthd, > + __struct_size(mthd) + size); > NVIF_ERRON(ret, &outp->object, "[HDA_ELD head:%d size:%d]", head, size); > return ret; > } > -- > 2.43.0 >
On 28/03/25 09:05, Danilo Krummrich wrote: > On Fri, Mar 28, 2025 at 08:45:32AM -0600, Gustavo A. R. Silva wrote: >> -Wflex-array-member-not-at-end was introduced in GCC-14, and we are >> getting ready to enable it, globally. >> >> 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 these changes, fix the following warning: >> >> drivers/gpu/drm/nouveau/nvif/outp.c:199:45: 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/nvif/outp.c | 16 +++++++--------- >> 1 file changed, 7 insertions(+), 9 deletions(-) >> >> diff --git a/drivers/gpu/drm/nouveau/nvif/outp.c b/drivers/gpu/drm/nouveau/nvif/outp.c >> index 6daeb7f0b09b..403cf16d5e84 100644 >> --- a/drivers/gpu/drm/nouveau/nvif/outp.c >> +++ b/drivers/gpu/drm/nouveau/nvif/outp.c >> @@ -195,20 +195,18 @@ nvif_outp_dp_aux_pwr(struct nvif_outp *outp, bool enable) >> int >> nvif_outp_hda_eld(struct nvif_outp *outp, int head, void *data, u32 size) >> { >> - struct { >> - struct nvif_outp_hda_eld_v0 mthd; >> - u8 data[128]; >> - } args; >> + DEFINE_RAW_FLEX(struct nvif_outp_hda_eld_v0, mthd, data, 128); >> int ret; >> >> - if (WARN_ON(size > ARRAY_SIZE(args.data))) >> + if (WARN_ON(size > 128)) > > Seems a bit unfortunate that the size is duplicated here. For now, I think we can do something like this instead: - if (WARN_ON(size > ARRAY_SIZE(args.data))) + if (WARN_ON(size > (__struct_size(mthd) - sizeof(*mthd)))) Thanks -Gustavo > > Can we have an accessor macro to derive the size for us? > > union { > u8 bytes[struct_size_t(type, member, count)]; > type obj; > } name##_u initializer; > > Maybe a macro that returns the size difference between bytes and obj? > >> return -EINVAL; >> >> - args.mthd.version = 0; >> - args.mthd.head = head; >> + mthd->version = 0; >> + mthd->head = head; >> >> - memcpy(args.data, data, size); >> - ret = nvif_mthd(&outp->object, NVIF_OUTP_V0_HDA_ELD, &args, sizeof(args.mthd) + size); >> + memcpy(mthd->data, data, size); >> + ret = nvif_mthd(&outp->object, NVIF_OUTP_V0_HDA_ELD, mthd, >> + __struct_size(mthd) + size); >> NVIF_ERRON(ret, &outp->object, "[HDA_ELD head:%d size:%d]", head, size); >> return ret; >> } >> -- >> 2.43.0 >> >
diff --git a/drivers/gpu/drm/nouveau/nvif/outp.c b/drivers/gpu/drm/nouveau/nvif/outp.c index 6daeb7f0b09b..403cf16d5e84 100644 --- a/drivers/gpu/drm/nouveau/nvif/outp.c +++ b/drivers/gpu/drm/nouveau/nvif/outp.c @@ -195,20 +195,18 @@ nvif_outp_dp_aux_pwr(struct nvif_outp *outp, bool enable) int nvif_outp_hda_eld(struct nvif_outp *outp, int head, void *data, u32 size) { - struct { - struct nvif_outp_hda_eld_v0 mthd; - u8 data[128]; - } args; + DEFINE_RAW_FLEX(struct nvif_outp_hda_eld_v0, mthd, data, 128); int ret; - if (WARN_ON(size > ARRAY_SIZE(args.data))) + if (WARN_ON(size > 128)) return -EINVAL; - args.mthd.version = 0; - args.mthd.head = head; + mthd->version = 0; + mthd->head = head; - memcpy(args.data, data, size); - ret = nvif_mthd(&outp->object, NVIF_OUTP_V0_HDA_ELD, &args, sizeof(args.mthd) + size); + memcpy(mthd->data, data, size); + ret = nvif_mthd(&outp->object, NVIF_OUTP_V0_HDA_ELD, mthd, + __struct_size(mthd) + size); NVIF_ERRON(ret, &outp->object, "[HDA_ELD head:%d size:%d]", head, size); return ret; }
-Wflex-array-member-not-at-end was introduced in GCC-14, and we are getting ready to enable it, globally. 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 these changes, fix the following warning: drivers/gpu/drm/nouveau/nvif/outp.c:199:45: 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/nvif/outp.c | 16 +++++++--------- 1 file changed, 7 insertions(+), 9 deletions(-)