linux-kernel - Re: [PATCH] drm/i915: Remove unneeded double drm_rect_visible call in check_overlay

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Date: Thu, 29 Feb 2024 14:30:29 +0200
From: Ville Syrjälä <ville.syrjala@...ux.intel.com>
To: Nikita Kiryushin <kiryushin@...ud.ru>
Cc: Jani Nikula <jani.nikula@...ux.intel.com>,
	Rodrigo Vivi <rodrigo.vivi@...el.com>,
	Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
	Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>,
	David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>,
	Manasi Navare <manasi.d.navare@...el.com>,
	intel-gfx@...ts.freedesktop.org, intel-xe@...ts.freedesktop.org,
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
	project@...uxtesting.org
Subject: Re: [PATCH] drm/i915: Remove unneeded double drm_rect_visible call
 in check_overlay_dst

On Wed, Feb 28, 2024 at 09:32:47PM +0300, Nikita Kiryushin wrote:
> 
> check_overlay_dst for clipped is called 2 times: in drm_rect_intersect 
> and than directly. Change second call for check of drm_rect_intersect 
> result to save some time (in locked code section).
> 
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
> 
> Fixes: 8d8b2dd3995f ("drm/i915: Make the PIPESRC rect relative to the 
> entire bigjoiner area")
> Signed-off-by: Nikita Kiryushin <kiryushin@...ud.ru>
> ---
>   drivers/gpu/drm/i915/display/intel_overlay.c | 3 +--
>   1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_overlay.c 
> b/drivers/gpu/drm/i915/display/intel_overlay.c
> index 2b1392d5a902..1cda1c163a92 100644
> --- a/drivers/gpu/drm/i915/display/intel_overlay.c
> +++ b/drivers/gpu/drm/i915/display/intel_overlay.c
> @@ -972,9 +972,8 @@ static int check_overlay_dst(struct intel_overlay 
> *overlay,
>   		      rec->dst_width, rec->dst_height);
>    	clipped = req;
> -	drm_rect_intersect(&clipped, &crtc_state->pipe_src);
>   -	if (!drm_rect_visible(&clipped) ||
> +	if (!drm_rect_intersect(&clipped, &crtc_state->pipe_src) ||

I prefer the current way where we have no side effects in
the if statement.

>   	    !drm_rect_equals(&clipped, &req))
>   		return -EINVAL;
>   -- 2.34.1

-- 
Ville Syrjälä
Intel