drm: Warn about negative sizes when calculating scale factor

Passing negative width/hight to scale factor calculations is not
legal. Let's WARN if that happens.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: http://patchwork.freedesktop.org/patch/msgid/1469549224-1860-2-git-send-email-ville.syrjala@linux.intel.com

diff --git a/drivers/gpu/drm/drm_rect.c b/drivers/gpu/drm/drm_rect.c
index 4063f6e..73e53a8 100644 (file)
--- a/drivers/gpu/drm/drm_rect.c
+++ b/drivers/gpu/drm/drm_rect.c
@@ -100,7 +100,7 @@ static int drm_calc_scale(int src, int dst)
 {
        int scale = 0;
 
-       if (src < 0 || dst < 0)
+       if (WARN_ON(src < 0 || dst < 0))
                return -EINVAL;
 
        if (dst == 0)