linux-kernel - Re: [PATCH RESEND] drm/msm/dpu: Delete a variable initialisation before a null pointer check in two functions

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Message-ID: <k7un3bjavyt4ogscgc7jn7thfobegaguqqiy7gtypmq6vq7zox@l4bsevbsjrud>
Date: Mon, 3 Mar 2025 01:01:40 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Markus Elfring <Markus.Elfring@....de>
Cc: kernel-janitors@...r.kernel.org, freedreno@...ts.freedesktop.org, 
	dri-devel@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org, 
	Abhinav Kumar <quic_abhinavk@...cinc.com>, Archit Taneja <architt@...eaurora.org>, 
	Daniel Vetter <daniel@...ll.ch>, David Airlie <airlied@...il.com>, 
	Jeykumar Sankaran <jsanka@...eaurora.org>, Jordan Crouse <jordan@...micpenguin.net>, 
	Marijn Suijten <marijn.suijten@...ainline.org>, Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>, 
	Simona Vetter <simona@...ll.ch>, Vinod Koul <vkoul@...nel.org>, cocci@...ia.fr, 
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH RESEND] drm/msm/dpu: Delete a variable initialisation
 before a null pointer check in two functions

On Sun, Mar 02, 2025 at 09:56:00PM +0100, Markus Elfring wrote:
> From: Markus Elfring <elfring@...rs.sourceforge.net>
> Date: Tue, 11 Apr 2023 18:24:24 +0200
> 
> The address of a data structure member was determined before
> a corresponding null pointer check in the implementation of
> the functions “dpu_hw_pp_enable_te” and “dpu_hw_pp_get_vsync_info”.
> 
> Thus avoid the risk for undefined behaviour by removing extra
> initialisations for the variable “c” (also because it was already
> reassigned with the same value behind this pointer check).
> 
> This issue was detected by using the Coccinelle software.

Please don't send resends and/or new iterations in response to your
previous patchsets. Otherwise they have a pretty high chance to be
ignored by the maintainers. Use a fresh git-send-email command to send
new patchset.

> 
> Fixes: 25fdd5933e4c ("drm/msm: Add SDM845 DPU support")
> Signed-off-by: Markus Elfring <elfring@...rs.sourceforge.net>
> ---
>  drivers/gpu/drm/msm/disp/dpu1/dpu_hw_pingpong.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_pingpong.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_pingpong.c
> index 0fcad9760b6f..870ab3ebbc94 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_pingpong.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_pingpong.c
> @@ -176,7 +176,7 @@ static int dpu_hw_pp_enable_te(struct dpu_hw_pingpong *pp, bool enable)
>  static int dpu_hw_pp_connect_external_te(struct dpu_hw_pingpong *pp,
>  		bool enable_external_te)
>  {
> -	struct dpu_hw_blk_reg_map *c = &pp->hw;
> +	struct dpu_hw_blk_reg_map *c;
>  	u32 cfg;
>  	int orig;
> 
> @@ -221,7 +221,7 @@ static int dpu_hw_pp_get_vsync_info(struct dpu_hw_pingpong *pp,
> 
>  static u32 dpu_hw_pp_get_line_count(struct dpu_hw_pingpong *pp)
>  {
> -	struct dpu_hw_blk_reg_map *c = &pp->hw;
> +	struct dpu_hw_blk_reg_map *c;
>  	u32 height, init;
>  	u32 line = 0xFFFF;
> 
> --
> 2.40.0
> 

-- 
With best wishes
Dmitry