Re: [PATCH RESEND] drm/msm/dpu: Fix variable dereferenced before check

From: Abhinav Kumar <quic_abhinavk@quicinc.com>
To: sunliming <sunliming@kylinos.cn>, <robdclark@gmail.com>,
	<dmitry.baryshkov@linaro.org>
Cc: <linux-kernel@vger.kernel.org>, <kelulanainsley@gmail.com>,
	<freedreno@lists.freedesktop.org>,
	kernel test robot <lkp@intel.com>,
	"Dan Carpenter" <dan.carpenter@oracle.com>
Subject: Re: [PATCH RESEND] drm/msm/dpu: Fix variable dereferenced before check
Date: Thu, 23 Jun 2022 10:32:51 -0700	[thread overview]
Message-ID: <5736c38e-b262-0697-be77-b5126fe4d65b@quicinc.com> (raw)
In-Reply-To: <20220623012707.453972-1-sunliming@kylinos.cn>


On 6/22/2022 6:27 PM, sunliming wrote:
> Fixes the following smatch warning:
> 
> drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_wb.c:261
> dpu_encoder_phys_wb_atomic_check() warn: variable dereferenced before check 'conn_state'
> 
> Signed-off-by: sunliming <sunliming@kylinos.cn>
> Reported-by: kernel test robot <lkp@intel.com>
> Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Fixes: d7d0e73f7de3 ("drm/msm/dpu: introduce the dpu_encoder_phys_* for 
writeback")
> ---
>   drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_wb.c | 10 +++++-----
>   1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_wb.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_wb.c
> index 59da348ff339..0ec809ab06e7 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_wb.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_wb.c
> @@ -252,11 +252,6 @@ static int dpu_encoder_phys_wb_atomic_check(
>   	DPU_DEBUG("[atomic_check:%d, \"%s\",%d,%d]\n",
>   			phys_enc->wb_idx, mode->name, mode->hdisplay, mode->vdisplay);
>   
> -	if (!conn_state->writeback_job || !conn_state->writeback_job->fb)
> -		return 0;
> -
> -	fb = conn_state->writeback_job->fb;
> -
>   	if (!conn_state || !conn_state->connector) {
>   		DPU_ERROR("invalid connector state\n");
>   		return -EINVAL;
> @@ -267,6 +262,11 @@ static int dpu_encoder_phys_wb_atomic_check(
>   		return -EINVAL;
>   	}
>   
> +	if (!conn_state->writeback_job || !conn_state->writeback_job->fb)
> +		return 0;
> +
> +	fb = conn_state->writeback_job->fb;
> +
>   	DPU_DEBUG("[fb_id:%u][fb:%u,%u]\n", fb->base.id,
>   			fb->width, fb->height);
>