linux-kernel - Re: [PATCH] drm/msm/disp/dpu1/dpu_encoder: Drop unnecessary NULL checks after container

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Message-ID: <73c997e5-79dc-f269-f649-d5bc54c2e86c@linaro.org>
Date:   Wed, 26 May 2021 04:00:50 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Guenter Roeck <linux@...ck-us.net>, Rob Clark <robdclark@...il.com>
Cc:     Sean Paul <sean@...rly.run>, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>, linux-arm-msm@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/msm/disp/dpu1/dpu_encoder: Drop unnecessary NULL
 checks after container_of

On 25/05/2021 14:29, Guenter Roeck wrote:
> The result of container_of() operations is never NULL unless the embedded
> element is the first element of the structure. This is not the case here.
> The NULL checks on the result of container_of() are therefore unnecessary
> and misleading. Remove them.
> 
> This change was made automatically with the following Coccinelle script.
> 
> @@
> type t;
> identifier v;
> statement s;
> @@
> 
> <+...
> (
>    t v = container_of(...);
> |
>    v = container_of(...);
> )
>    ...
>    when != v
> - if (\( !v \| v == NULL \) ) s
> ...+>
> 
> Signed-off-by: Guenter Roeck <linux@...ck-us.net>


Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>

> ---
>   drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 10 ----------
>   1 file changed, 10 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> index 8d942052db8a..a573fe211375 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> @@ -1453,11 +1453,6 @@ static void dpu_encoder_off_work(struct work_struct *work)
>   	struct dpu_encoder_virt *dpu_enc = container_of(work,
>   			struct dpu_encoder_virt, delayed_off_work.work);
>   
> -	if (!dpu_enc) {
> -		DPU_ERROR("invalid dpu encoder\n");
> -		return;
> -	}
> -
>   	dpu_encoder_resource_control(&dpu_enc->base,
>   						DPU_ENC_RC_EVENT_ENTER_IDLE);
>   
> @@ -1797,11 +1792,6 @@ static void dpu_encoder_vsync_event_work_handler(struct kthread_work *work)
>   			struct dpu_encoder_virt, vsync_event_work);
>   	ktime_t wakeup_time;
>   
> -	if (!dpu_enc) {
> -		DPU_ERROR("invalid dpu encoder\n");
> -		return;
> -	}
> -
>   	if (dpu_encoder_vsync_time(&dpu_enc->base, &wakeup_time))
>   		return;
>   
> 


-- 
With best wishes
Dmitry