Re: [PATCH]Silancing a false positive: "may be used uninitialized"

From: Simon Horman
Date: Sun Dec 20 2009 - 04:56:53 EST


On Sun, Dec 20, 2009 at 09:03:27AM +0200, Marin Mitov wrote:
> Hello all,
>
> Silancing a false positive:
> warning: 'width' may be used uninitialized in this function
> drivers/gpu/drm/drm_edid.c

Is it guaranteed that the switch will always see a value covered by the
four cases it has? If not width would be used without having been initialised.

Perhaps adding

default:
BUG();

would be worthwhile?

>
> Signed-off-by: Marin Mitov <mitov@xxxxxxxxxxx>
> ==========================================================================
> --- a/drivers/gpu/drm/drm_edid.c 2009-12-20 07:43:57.000000000 +0200
> +++ b/drivers/gpu/drm/drm_edid.c 2009-12-20 07:45:49.000000000 +0200
> @@ -913,7 +913,7 @@
> const int rates[] = { 60, 85, 75, 60, 50 };
>
> for (i = 0; i < 4; i++) {
> - int width, height;
> + int uninitialized_var(width), height;
> cvt = &(timing->data.other_data.data.cvt[i]);
>
> height = (cvt->code[0] + ((cvt->code[1] & 0xf0) << 8) + 1) * 2;
> --
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