Re: [PATCH v2 2/5] iommu/mediatek: Add error path for loop of mm_dts_parse

[Robin Murphy <robin.murphy@arm.com>]

On 2022-06-16 06:42, Yong Wu wrote:
> The mtk_iommu_mm_dts_parse will parse the smi larbs nodes. if the i+1
> larb is parsed fail(return -EINVAL), we should of_node_put for the 0..i
> larbs. In the fail path, one of_node_put matches with of_parse_phandle in
> it.
> 
> Fixes: d2e9a1102cfc ("iommu/mediatek: Contain MM IOMMU flow with the MM TYPE")
> Signed-off-by: Yong Wu <yong.wu@mediatek.com>
> ---
>   drivers/iommu/mtk_iommu.c | 21 ++++++++++++++++-----
>   1 file changed, 16 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
> index 3b2489e8a6dd..ab24078938bf 100644
> --- a/drivers/iommu/mtk_iommu.c
> +++ b/drivers/iommu/mtk_iommu.c
> @@ -1071,12 +1071,12 @@ static int mtk_iommu_mm_dts_parse(struct device *dev, struct component_match **m
>   
>   		plarbdev = of_find_device_by_node(larbnode);
>   		if (!plarbdev) {
> -			of_node_put(larbnode);
> -			return -ENODEV;
> +			ret = -ENODEV;
> +			goto err_larbnode_put;
>   		}
>   		if (!plarbdev->dev.driver) {
> -			of_node_put(larbnode);
> -			return -EPROBE_DEFER;
> +			ret = -EPROBE_DEFER;
> +			goto err_larbnode_put;
>   		}
>   		data->larb_imu[id].dev = &plarbdev->dev;
>   
> @@ -1107,9 +1107,20 @@ static int mtk_iommu_mm_dts_parse(struct device *dev, struct component_match **m
>   			       DL_FLAG_STATELESS | DL_FLAG_PM_RUNTIME);
>   	if (!link) {
>   		dev_err(dev, "Unable to link %s.\n", dev_name(data->smicomm_dev));
> -		return -EINVAL;
> +		ret = -EINVAL;
> +		goto err_larbnode_put;
>   	}
>   	return 0;
> +
> +err_larbnode_put:
> +	while (i--) {
> +		larbnode = of_parse_phandle(dev->of_node, "mediatek,larbs", i);
> +		if (larbnode && of_device_is_available(larbnode)) {
> +			of_node_put(larbnode);
> +			of_node_put(larbnode);
> +		}

This looks a bit awkward - could we not just iterate through 
data->larb_imu and put dev->of_node for each valid dev?

Also, of_find_device_by_node() takes a reference on the struct device 
itself, so strictly we should be doing put_device() on those as well if 
we're bailing out.

Robin.

> +	}
> +	return ret;
>   }
>   
>   static int mtk_iommu_probe(struct platform_device *pdev)