linux-kernel - Re: [PATCH v4 3/6] iommu/mediatek: Add error path for loop of mm_dts

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Message-ID: <c5eca9b0154adf5a201ab89f3a9fa120b4519d25.camel@mediatek.com>
Date:   Wed, 7 Sep 2022 11:08:05 +0800
From:   Yong Wu <yong.wu@...iatek.com>
To:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        Joerg Roedel <joro@...tes.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Will Deacon <will@...nel.org>
CC:     Robin Murphy <robin.murphy@....com>, <iommu@...ts.linux.dev>,
        <iommu@...ts.linux-foundation.org>,
        <linux-mediatek@...ts.infradead.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <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 v4 3/6] iommu/mediatek: Add error path for loop of
 mm_dts_parse

On Tue, 2022-08-30 at 10:14 +0200, AngeloGioacchino Del Regno wrote:
> Il 24/08/22 08:43, Yong Wu ha scritto:
> > The mtk_iommu_mm_dts_parse will parse the smi larbs nodes. if the
> > i+1
> > larb is parsed fail, we should put_device for the 0..i larbs.
> > 
> > There are two places need to comment:
> > 1) The larbid may be not linear mapping, we should loop whole
> >     the array in the error path.
> > 2) I move this line position: "data->larb_imu[id].dev = &plarbdev-
> > >dev;"
> >     That means set data->larb_imu[id].dev before the error path.
> >     then we don't need "platform_device_put(plarbdev)" again while
> >     probe_defer case. All depend on "put_device" in the error path
> > in error
> >     cases.
> > 
> > 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 | 42 ++++++++++++++++++++++++++++----
> > -------
> >   1 file changed, 30 insertions(+), 12 deletions(-)

[...]

> > +
> > +err_larbdev_put:
> > +	/* id may be not linear mapping, loop whole the array */
> > +	for (i = 0; i < MTK_LARB_NR_MAX; i++) {
> 
> Since there may be a case in which the mapping is linear and we're
> doing teardown,
> I think it would be sensible to loop the other way around instead,
> from
> MTK_LARB_NR_MAX to 0.

Thanks very much. I will change from MTK_LARB_NR_MAX to 0.

> 
> Everything else looks good to me.
> 
> Cheers,
> Angelo
> 
> > +		if (!data->larb_imu[i].dev)
> > +			continue;
> > +		put_device(data->larb_imu[i].dev);
> > +	}
> > +	return ret;
> >   }
> >   
> >   static int mtk_iommu_probe(struct platform_device *pdev)
> 
>