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From:   Sedat Dilek <sedat.dilek@gmail.com>
Date:   Wed, 24 Feb 2021 18:40:09 +0100
Message-ID: <CA+icZUXGS_bbVRsMVJowVPTZpi8NYQ_18Ec9bXBTztWL6dA=hQ@mail.gmail.com>
Subject: Re: [PATCH] drm/amd/pm/swsmu: Avoid using structure_size
 uninitialized in smu_cmn_init_soft_gpu_metrics
To:     Nathan Chancellor <nathan@kernel.org>
Cc:     Alex Deucher <alexander.deucher@amd.com>,
        =?UTF-8?Q?Christian_K=C3=B6nig?= <christian.koenig@amd.com>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Kevin Wang <kevin1.wang@amd.com>,
        amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
        linux-kernel@vger.kernel.org,
        Clang-Built-Linux ML <clang-built-linux@googlegroups.com>
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On Thu, Feb 18, 2021 at 11:49 PM Nathan Chancellor <nathan@kernel.org> wrote:
>
> Clang warns:
>
> drivers/gpu/drm/amd/amdgpu/../pm/swsmu/smu_cmn.c:764:2: warning:
> variable 'structure_size' is used uninitialized whenever switch default
> is taken [-Wsometimes-uninitialized]
>         default:
>         ^~~~~~~
> drivers/gpu/drm/amd/amdgpu/../pm/swsmu/smu_cmn.c:770:23: note:
> uninitialized use occurs here
>         memset(header, 0xFF, structure_size);
>                              ^~~~~~~~~~~~~~
> drivers/gpu/drm/amd/amdgpu/../pm/swsmu/smu_cmn.c:753:25: note:
> initialize the variable 'structure_size' to silence this warning
>         uint16_t structure_size;
>                                ^
>                                 = 0
> 1 warning generated.
>
> Return in the default case, as the size of the header will not be known.
>
> Fixes: de4b7cd8cb87 ("drm/amd/pm/swsmu: unify the init soft gpu metrics function")
> Link: https://github.com/ClangBuiltLinux/linux/issues/1304
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>

I fell over this today with Linux v5.11-10201-gc03c21ba6f4e.

Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM/Clang v13-git

- Sedat -

> ---
>  drivers/gpu/drm/amd/pm/swsmu/smu_cmn.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/pm/swsmu/smu_cmn.c b/drivers/gpu/drm/amd/pm/swsmu/smu_cmn.c
> index bb620fdd4cd2..bcedd4d92e35 100644
> --- a/drivers/gpu/drm/amd/pm/swsmu/smu_cmn.c
> +++ b/drivers/gpu/drm/amd/pm/swsmu/smu_cmn.c
> @@ -762,7 +762,7 @@ void smu_cmn_init_soft_gpu_metrics(void *table, uint8_t frev, uint8_t crev)
>                 structure_size = sizeof(struct gpu_metrics_v2_0);
>                 break;
>         default:
> -               break;
> +               return;
>         }
>
>  #undef METRICS_VERSION
> --
> 2.30.1
>
> --
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