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Date:   Wed, 8 Sep 2021 20:34:40 +0200
From:   Daniel Vetter <daniel@ffwll.ch>
To:     "Alex Xu (Hello71)" <alex_y_xu@yahoo.ca>
Cc:     dri-devel@lists.freedesktop.org, ville.syrjala@linux.intel.com,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] drm/plane-helper: fix uninitialized variable reference
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Mail-Followup-To: "Alex Xu (Hello71)" <alex_y_xu@yahoo.ca>,
        dri-devel@lists.freedesktop.org, ville.syrjala@linux.intel.com,
        linux-kernel@vger.kernel.org
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 <20210907140836.323149-1-alex_y_xu@yahoo.ca>
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On Tue, Sep 07, 2021 at 10:08:36AM -0400, Alex Xu (Hello71) wrote:
> drivers/gpu/drm/drm_plane_helper.c: In function 'drm_primary_helper_update':
> drivers/gpu/drm/drm_plane_helper.c:113:32: error: 'visible' is used uninitialized [-Werror=uninitialized]
>   113 |         struct drm_plane_state plane_state = {
>       |                                ^~~~~~~~~~~
> drivers/gpu/drm/drm_plane_helper.c:178:14: note: 'visible' was declared here
>   178 |         bool visible;
>       |              ^~~~~~~
> cc1: all warnings being treated as errors
> 
> visible is an output, not an input. in practice this use might turn out
> OK but it's still UB.
> 
> Fixes: df86af9133 ("drm/plane-helper: Add drm_plane_helper_check_state()")

I need a signed-off-by from you before I can merge this. See

https://dri.freedesktop.org/docs/drm/process/submitting-patches.html#sign-your-work-the-developer-s-certificate-of-origin

Patch lgtm otherwise.
-Daniel

> ---
>  drivers/gpu/drm/drm_plane_helper.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/drm_plane_helper.c b/drivers/gpu/drm/drm_plane_helper.c
> index 5b2d0ca03705..838b32b70bce 100644
> --- a/drivers/gpu/drm/drm_plane_helper.c
> +++ b/drivers/gpu/drm/drm_plane_helper.c
> @@ -123,7 +123,6 @@ static int drm_plane_helper_check_update(struct drm_plane *plane,
>  		.crtc_w = drm_rect_width(dst),
>  		.crtc_h = drm_rect_height(dst),
>  		.rotation = rotation,
> -		.visible = *visible,
>  	};
>  	struct drm_crtc_state crtc_state = {
>  		.crtc = crtc,
> -- 
> 2.33.0
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch