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

From: Yong Wu
Date: Thu Jun 16 2022 - 06:08:34 EST


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@xxxxxxxxxxxx>
> > ---
> > 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)