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

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Date:   Wed, 22 Feb 2023 17:09:40 +0100
From:   Thomas Zimmermann <tzimmermann@...e.de>
To:     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,
        nathan@...nel.org, ndesaulniers@...gle.com, javierm@...hat.com
Cc:     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

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

Best regards
Thomas

> ---
>   drivers/gpu/drm/msm/msm_fbdev.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/msm/msm_fbdev.c b/drivers/gpu/drm/msm/msm_fbdev.c
> index c804e5ba682a..c1356aff87da 100644
> --- a/drivers/gpu/drm/msm/msm_fbdev.c
> +++ b/drivers/gpu/drm/msm/msm_fbdev.c
> @@ -142,7 +142,7 @@ struct drm_fb_helper *msm_fbdev_init(struct drm_device *dev)
>   
>   	fbdev = kzalloc(sizeof(*fbdev), GFP_KERNEL);
>   	if (!fbdev)
> -		goto fail;
> +		return NULL;
>   
>   	helper = &fbdev->base;
>   

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev

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