linux-kernel - Re: [PATCH] drm/vmwgfx: Zero initialize handle in vmw_execbuf

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Date:   Mon, 11 Mar 2019 10:01:16 -0700
From:   Deepak Singh Rawat <drawat@...are.com>
To:     Nathan Chancellor <natechancellor@...il.com>,
        VMware Graphics <linux-graphics-maintainer@...are.com>,
        Thomas Hellstrom <thellstrom@...are.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>
CC:     <dri-devel@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>,
        <clang-built-linux@...glegroups.com>,
        Nick Desaulniers <ndesaulniers@...gle.com>
Subject: Re: [PATCH] drm/vmwgfx: Zero initialize handle in
 vmw_execbuf_process

Hi Nathan,

Thanks for doing this. I will include this in vmwgfx-next.

Reviewed-by: Deepak Rawat <drawat@...are.com>

On Thu, 2019-03-07 at 15:26 -0700, Nathan Chancellor wrote:
> When building with -Wsometimes-uninitialized, Clang warns:
> 
> drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c:3964:7: warning: variable
> 'handle' is used uninitialized whenever '?:' condition is false
> [-Wsometimes-uninitialized]
> 
> It's not wrong; however, in practice, this is never an issue because
> the value of handle isn't used when user_fence_rep is NULL because
> vmw_execbuf_copy_fence_user returns immediately when that is the
> case.
> Just zero initialize this variable so that Clang no longer warns.
> 
> Link: 
> https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2FClangBuiltLinux%2Flinux%2Fissues%2F397&amp;data=02%7C01%7Cdrawat%40vmware.com%7C6b9c429d16d844a5740c08d6a34bedb4%7Cb39138ca3cee4b4aa4d6cd83d9dd62f0%7C0%7C0%7C636875943916412703&amp;sdata=Yf7%2BzrbZS96yNJQewYQQ7YsHUDtJSvPaomyTJFZjsDk%3D&amp;reserved=0
> Signed-off-by: Nathan Chancellor <natechancellor@...il.com>
> ---
>  drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
> b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
> index 88b8178d4687..4ba06c2828a1 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
> @@ -3829,7 +3829,7 @@ int vmw_execbuf_process(struct drm_file
> *file_priv,
>  	struct vmw_sw_context *sw_context = &dev_priv->ctx;
>  	struct vmw_fence_obj *fence = NULL;
>  	struct vmw_cmdbuf_header *header;
> -	uint32_t handle;
> +	uint32_t handle = 0;
>  	int ret;
>  	int32_t out_fence_fd = -1;
>  	struct sync_file *sync_file = NULL;