New warning in linus/master

[Thomas Weißschuh]

Hi Ricardo,

On Wed, Apr 22, 2026 at 11:51:45AM +0800, Ricardo Ribalda wrote:
> Media-CI has found a couple of new warnings in the latest kernel
> version for aarch64 and powerpc. They get fixed with this patch and
> before moving I wanted to know if this was under your radar.

Thanks for the report. I was not aware of these so far.

> diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile
> index 7dec05dd33b7..65914842fae0 100644
> --- a/arch/arm64/kernel/vdso/Makefile
> +++ b/arch/arm64/kernel/vdso/Makefile
> @@ -50,7 +50,7 @@ CFLAGS_vgettimeofday.o = $(CC_FLAGS_ADD_VDSO)
>  CFLAGS_vgetrandom.o = $(CC_FLAGS_ADD_VDSO)
> 
>  ifneq ($(c-gettimeofday-y),)
> -  CFLAGS_vgettimeofday.o += -include $(c-gettimeofday-y)
> +  CFLAGS_vgettimeofday.o += -include $(c-gettimeofday-y)
> -Wno-maybe-uninitialized
>  endif

(...)

I'd like to know exactly what is going on before suppressing the warning.
It is a non-standard warning, only enabled by *some* of the vDSO builds
for some reason.

> https://gitlab.freedesktop.org/linux-media/users/ribalda/-/pipelines/1649144/test_report?job_name=cross-gcc

While I was able to download a configuration from this job and also use the
same container image, I can not reproduce the issue. Is the configuration the
full one or only the template?

Could you provide full reproduction steps?

> CONFIG_CC_VERSION_TEXT="aarch64-linux-gnu-gcc (Debian 15.2.0-16) 15.2.0"

The linked test log shows GCC 14.2, not 15.2.
Not that I could reproduce it with either one...

>   SYNC    include/config/auto.conf
>   CC      arch/arm64/kernel/vdso/vgettimeofday.o
> In file included from <command-line>:
> In function ‘vdso_set_timespec’,
>     inlined from ‘do_aux’ at /workdir/lib/vdso/gettimeofday.c:266:2,
>     inlined from ‘__cvdso_clock_gettime_common’ at
> /workdir/lib/vdso/gettimeofday.c:293:10,
>     inlined from ‘__cvdso_clock_gettime_data.constprop’ at
> /workdir/lib/vdso/gettimeofday.c:306:7:
> /workdir/lib/vdso/gettimeofday.c:104:26: warning: ‘sec’ may be used
> uninitialized [-Wmaybe-uninitialized]
>   104 |         ts->tv_sec = sec + __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns);
>       |                      ~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> /workdir/lib/vdso/gettimeofday.c: In function
> ‘__cvdso_clock_gettime_data.constprop’:
> /workdir/lib/vdso/gettimeofday.c:242:13: note: ‘sec’ was declared here
>   242 |         u64 sec, ns;
>       |             ^~~

The same pattern is used in some other do_ handlers, which do not generate this
warning. I also can't immediately see what is wrong.

(...)


Thomas