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From:   Alex Deucher <alexdeucher@gmail.com>
Date:   Tue, 29 Dec 2020 10:07:27 -0500
Message-ID: <CADnq5_N_2iYnh13p-z5vrvNK9rzKV-5TYtCC-FiEYjvi--_org@mail.gmail.com>
Subject: Re: [git pull] drm fixes for 5.11-rc1
To:     Linus Torvalds <torvalds@linux-foundation.org>,
        Harry Wentland <hwentlan@amd.com>,
        "Kazlauskas, Nicholas" <nicholas.kazlauskas@amd.com>,
        Hersen Wu <hersenxs.wu@amd.com>
Cc:     Dave Airlie <airlied@gmail.com>, Josip Pavic <Josip.Pavic@amd.com>,
        Bindu Ramamurthy <bindu.r@amd.com>,
        Alex Deucher <alexander.deucher@amd.com>,
        Daniel Vetter <daniel.vetter@ffwll.ch>,
        LKML <linux-kernel@vger.kernel.org>,
        dri-devel <dri-devel@lists.freedesktop.org>
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On Thu, Dec 24, 2020 at 5:28 PM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> On Wed, Dec 23, 2020 at 6:29 PM Dave Airlie <airlied@gmail.com> wrote:
> >
> > Xmas eve pull request present. Just some fixes that trickled in this
> > past week. Mostly amdgpu fixes, with a dma-buf/mips build fix and some
> > misc komeda fixes.
>
> Well, I already pulled and pushed out my merge, but only noticed
> afterwards that clang complains about this, and I think it's a real
> bug:
>
>   drivers/gpu/drm/amd/amdgpu/../display/dc/dcn10/dcn10_mpc.c:475:6: warning:
>      variable 'val' is used uninitialized whenever 'if' condition is
> false [-Wsometimes-uninitialized]
>
> and it sure is true: the code literally does
>
>         uint32_t val;
>
>         if (opp_id < MAX_OPP && REG(MUX[opp_id]))
>                 REG_GET(MUX[opp_id], MPC_OUT_MUX, &val);
>
>         return val;
>
> so clearly 'val' isn't initialized if that if-statement isn't true.
>
> I assume 'opp_id' is always presumed to be valid, but that code really
> is disgusting.
>
> Just make it return 0 (or whatever) for invalid, possibly together
> with a WARN_ON_ONCE(). Ok?

Harry, Nick, Hersen,

Can you take a look?

Thanks,

Alex

>
>              Linus
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