linux-kernel - Re: [PATCH v2 2/5] iommu/mediatek: Add error path for loop of mm_dts

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Date:   Thu, 16 Jun 2022 18:08:21 +0800
From:   Yong Wu <yong.wu@...iatek.com>
To:     Robin Murphy <robin.murphy@....com>
CC:     Joerg Roedel <joro@...tes.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Will Deacon <will@...nel.org>,
        <iommu@...ts.linux-foundation.org>,
        <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 v2 2/5] iommu/mediatek: Add error path for loop of
 mm_dts_parse

On Thu, 2022-06-16 at 09:59 +0100, Robin Murphy wrote:
> 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@...iatek.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?

It should work. Thanks very much.

> 
> 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.

Thanks for this hint. A new reference for me. I will add it.

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