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

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Message-ID: <CACGkMEtWyJKqQr2yRyhU5=5qg+EH06FXsHRabk3da5iwfCA4FQ@mail.gmail.com>
Date: Fri, 25 Jul 2025 16:38:25 +0800
From: Jason Wang <jasowang@...hat.com>
To: Naresh Kamboju <naresh.kamboju@...aro.org>
Cc: open list <linux-kernel@...r.kernel.org>, virtualization@...ts.linux.dev, 
	clang-built-linux <llvm@...ts.linux.dev>, lkft-triage@...ts.linaro.org, 
	Linux Regressions <regressions@...ts.linux.dev>, "Michael S. Tsirkin" <mst@...hat.com>, 
	Xuan Zhuo <xuanzhuo@...ux.alibaba.com>, Nathan Chancellor <nathan@...nel.org>, 
	Arnd Bergmann <arnd@...db.de>, Dan Carpenter <dan.carpenter@...aro.org>, 
	Anders Roxell <anders.roxell@...aro.org>, Ben Copeland <benjamin.copeland@...aro.org>
Subject: Re: next-20250725 i386 x86_64 virtio_ring.c error variable 'id' is
 uninitialized when used here [-Werror,-Wuninitialized]

On Fri, Jul 25, 2025 at 3:43 PM Naresh Kamboju
<naresh.kamboju@...aro.org> 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@...aro.org>
>
> ## 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@redhat.com/T/#u

Thanks