linux-kernel - Re: [PATCH v7 1/6] iommu/mediatek: Add platform_device

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Message-ID: <8549c4b4-bc0a-ab6d-dceb-e694af2e8148@gmail.com>
Date:   Tue, 22 Nov 2022 17:24:59 +0100
From:   Matthias Brugger <matthias.bgg@...il.com>
To:     Yong Wu <yong.wu@...iatek.com>, Joerg Roedel <joro@...tes.org>,
        Will Deacon <will@...nel.org>
Cc:     Robin Murphy <robin.murphy@....com>, iommu@...ts.linux.dev,
        linux-mediatek@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        mingyuan.ma@...iatek.com, yf.wang@...iatek.com,
        libo.kang@...iatek.com, chengci.xu@...iatek.com,
        youlin.pei@...iatek.com, anan.sun@...iatek.com,
        xueqi.zhang@...iatek.com, Guenter Roeck <groeck@...omium.org>,
        Dan Carpenter <dan.carpenter@...cle.com>
Subject: Re: [PATCH v7 1/6] iommu/mediatek: Add platform_device_put for
 recovering the device refcnt



On 18/10/2022 04:42, Yong Wu wrote:
> Add platform_device_put to match with of_find_device_by_node.
> 
> Meanwhile, I add a new variable "pcommdev" which is for smi common device.
> Otherwise, "platform_device_put(plarbdev)" for smi-common dev may be not
> readable. And add a checking for whether pcommdev is NULL.
> 
> Fixes: d2e9a1102cfc ("iommu/mediatek: Contain MM IOMMU flow with the MM TYPE")
> Signed-off-by: Yong Wu <yong.wu@...iatek.com>
> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>

Reviewed-by: Matthias Brugger <matthias.bgg@...il.com>

> ---
>   drivers/iommu/mtk_iommu.c | 11 ++++++++---
>   1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
> index 5a4e00e4bbbc..3189b585725f 100644
> --- a/drivers/iommu/mtk_iommu.c
> +++ b/drivers/iommu/mtk_iommu.c
> @@ -1043,7 +1043,7 @@ static int mtk_iommu_mm_dts_parse(struct device *dev, struct component_match **m
>   				  struct mtk_iommu_data *data)
>   {
>   	struct device_node *larbnode, *smicomm_node, *smi_subcomm_node;
> -	struct platform_device *plarbdev;
> +	struct platform_device *plarbdev, *pcommdev;
>   	struct device_link *link;
>   	int i, larb_nr, ret;
>   
> @@ -1074,12 +1074,14 @@ static int mtk_iommu_mm_dts_parse(struct device *dev, struct component_match **m
>   		}
>   		if (!plarbdev->dev.driver) {
>   			of_node_put(larbnode);
> +			platform_device_put(plarbdev);
>   			return -EPROBE_DEFER;
>   		}
>   		data->larb_imu[id].dev = &plarbdev->dev;
>   
>   		component_match_add_release(dev, match, component_release_of,
>   					    component_compare_of, larbnode);
> +		platform_device_put(plarbdev);
>   	}
>   
>   	/* Get smi-(sub)-common dev from the last larb. */
> @@ -1097,12 +1099,15 @@ static int mtk_iommu_mm_dts_parse(struct device *dev, struct component_match **m
>   	else
>   		smicomm_node = smi_subcomm_node;
>   
> -	plarbdev = of_find_device_by_node(smicomm_node);
> +	pcommdev = of_find_device_by_node(smicomm_node);
>   	of_node_put(smicomm_node);
> -	data->smicomm_dev = &plarbdev->dev;
> +	if (!pcommdev)
> +		return -ENODEV;
> +	data->smicomm_dev = &pcommdev->dev;
>   
>   	link = device_link_add(data->smicomm_dev, dev,
>   			       DL_FLAG_STATELESS | DL_FLAG_PM_RUNTIME);
> +	platform_device_put(pcommdev);
>   	if (!link) {
>   		dev_err(dev, "Unable to link %s.\n", dev_name(data->smicomm_dev));
>   		return -EINVAL;