linux-kernel - Re: [PATCH] drm/msm: return early when allocating fbdev fails

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Message-ID: <Y/ZdJW3dxMVMGYlp@dev-arch.thelio-3990X>
Date:   Wed, 22 Feb 2023 11:21:25 -0700
From:   Nathan Chancellor <nathan@...nel.org>
To:     Thomas Zimmermann <tzimmermann@...e.de>
Cc:     Tom Rix <trix@...hat.com>, robdclark@...il.com,
        quic_abhinavk@...cinc.com, dmitry.baryshkov@...aro.org,
        sean@...rly.run, airlied@...il.com, daniel@...ll.ch,
        ndesaulniers@...gle.com, javierm@...hat.com,
        linux-arm-msm@...r.kernel.org, llvm@...ts.linux.dev,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org
Subject: Re: [PATCH] drm/msm: return early when allocating fbdev fails

On Wed, Feb 22, 2023 at 05:09:40PM +0100, Thomas Zimmermann wrote:
> Hi
> 
> Am 22.02.23 um 16:56 schrieb Tom Rix:
> > building with clang and W=1 reports
> > drivers/gpu/drm/msm/msm_fbdev.c:144:6: error: variable 'helper' is used
> >    uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
> >    if (!fbdev)
> >        ^~~~~~
> > 
> > helper is only initialized after fbdev succeeds, so is in a garbage state at
> > the fail: label.  There is nothing to unwinded if fbdev alloaction fails,
> > return NULL.
> > 
> > Fixes: 3fb1f62f80a1 ("drm/fb-helper: Remove drm_fb_helper_unprepare() from drm_fb_helper_fini()")
> > Signed-off-by: Tom Rix <trix@...hat.com>
> 
> Already fixed here: https://lore.kernel.org/dri-devel/08e3340e-b459-0e60-4bba-30716b675e05@suse.de/T/#t

There is also:

../drivers/gpu/drm/omapdrm/omap_fbdev.c:235:6: error: variable 'helper' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
        if (!fbdev)
            ^~~~~~
../drivers/gpu/drm/omapdrm/omap_fbdev.c:259:26: note: uninitialized use occurs here
        drm_fb_helper_unprepare(helper);
                                ^~~~~~
../drivers/gpu/drm/omapdrm/omap_fbdev.c:235:2: note: remove the 'if' if its condition is always false
        if (!fbdev)
        ^~~~~~~~~~~
../drivers/gpu/drm/omapdrm/omap_fbdev.c:228:30: note: initialize the variable 'helper' to silence this warning
        struct drm_fb_helper *helper;
                                    ^
                                     = NULL
1 error generated.

Is the fix the same as the one you have linked above?

Cheers,
Nathan