linux-kernel - Re: [PATCH] media: platform: mtk-mdp3: Fix return value check in mdp

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Date:   Wed, 30 Nov 2022 10:44:01 +0100
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     Qiheng Lin <linqiheng@...wei.com>, mchehab@...nel.org,
        matthias.bgg@...il.com
Cc:     linux-media@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] media: platform: mtk-mdp3: Fix return value check in
 mdp_probe()

Il 30/11/22 09:13, Qiheng Lin ha scritto:
> In case of error, the function mtk_mutex_get()
> returns ERR_PTR() and never returns NULL. The NULL test in the
> return value check should be replaced with IS_ERR().
> 
> Fixes: 61890ccaefaf ("media: platform: mtk-mdp3: add MediaTek MDP3 driver")
> Signed-off-by: Qiheng Lin <linqiheng@...wei.com>
> ---
>   drivers/media/platform/mediatek/mdp3/mtk-mdp3-core.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/media/platform/mediatek/mdp3/mtk-mdp3-core.c b/drivers/media/platform/mediatek/mdp3/mtk-mdp3-core.c
> index c413e59d4286..7a2d992dd842 100644
> --- a/drivers/media/platform/mediatek/mdp3/mtk-mdp3-core.c
> +++ b/drivers/media/platform/mediatek/mdp3/mtk-mdp3-core.c
> @@ -207,8 +207,8 @@ static int mdp_probe(struct platform_device *pdev)
>   	}
>   	for (i = 0; i < MDP_PIPE_MAX; i++) {
>   		mdp->mdp_mutex[i] = mtk_mutex_get(&mm_pdev->dev);
> -		if (!mdp->mdp_mutex[i]) {
> -			ret = -ENODEV;
> +		if (IS_ERR(mdp->mdp_mutex[i])) {
> +			ret = PTR_ERR(mdp->mdp_mutex[i]);
>   			goto err_return;
>   		}
>   	}
> 

That's true, and I fully agree.
While you're at it, can you also fix the err_return case?

if (mdp)
	for ...
		if (!IS_ERR_OR_NULL(mdp->mdp_mutex[i]))
			mtk_mutex_put(...)


Thanks,
Angelo