Re: next-20250725 i386 x86_64 virtio_ring.c error variable 'id' is uninitialized when used here [-Werror,-Wuninitialized]

[Jason Wang]

On Fri, Jul 25, 2025 at 3:43 PM Naresh Kamboju
<naresh.kamboju@xxxxxxxxxx> wrote:
>
> Regressions noticed while building x86_64 and i386 builds with clang-nightly
> and clang-20 toolchains on the Linux next-20250725 tag.
>
> First seen on the Linux next-20250725
> Good: next-20250724
> Bad:  next-20250725
>
> Regression Analysis:
> - New regression? Yes
> - Reproducibility? Yes
>
> ## Build regressions
> * i386, build
>   - clang-20-defconfig
>   - clang-nightly-defconfig
>
> * x86_64, build
>   - clang-20-allyesconfig
>   - clang-20-lkftconfig
>   - clang-20-lkftconfig-compat
>   - clang-20-lkftconfig-kcsan
>   - clang-20-lkftconfig-no-kselftest-frag
>   - clang-20-x86_64_defconfig
>   - clang-nightly-lkftconfig
>   - clang-nightly-lkftconfig-hardening
>   - clang-nightly-lkftconfig-kselftest
>   - clang-nightly-lkftconfig-lto-full
>   - clang-nightly-lkftconfig-lto-thing
>   - clang-nightly-x86_64_defconfig
>   - gcc-13-allyesconfig
>   - korg-clang-20-lkftconfig-hardening
>   - korg-clang-20-lkftconfig-lto-full
>   - korg-clang-20-lkftconfig-lto-thing
>   - rustclang-nightly-lkftconfig-kselftest
>
> Build regression: next-20250725 i386 x86_64 virtio_ring.c error
> variable 'id' is uninitialized when used here
> [-Werror,-Wuninitialized]
>
> Reported-by: Linux Kernel Functional Testing <lkft@xxxxxxxxxx>
>
> ## Build log
> drivers/virtio/virtio_ring.c:2113:40: error: variable 'id' is
> uninitialized when used here [-Werror,-Wuninitialized]
>  2113 |                 BAD_RING(vq, "id %u out of range\n", id);
>       |                                                      ^~
> drivers/virtio/virtio_ring.c:2077:19: note: initialize the variable
> 'id' to silence this warning
>  2077 |         u16 last_used, id, last_used_idx;
>       |                          ^
>       |                           = 0
> 1 error generated.
>

A fix has been posted here:

https://lore.kernel.org/virtualization/20250725083635.73355-1-jasowang@xxxxxxxxxx/T/#u

Thanks