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

On Thu, 2022-06-16 at 11:31 +0100, Robin Murphy wrote:

On 2022-06-16 11:08, Yong Wu wrote:

quoted

On Thu, 2022-06-16 at 09:59 +0100, Robin Murphy wrote:

quoted

On 2022-06-16 06:42, Yong Wu wrote:

quoted

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(-)

[snip..]

quoted

quoted

quoted

+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.

quoted

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.

In fact, thinking about it some more we may as well do the
of_node_put() 
unconditionally immediately after the of_find_device_by_node() call, 

of_node_put is called in component_release_of in the normal case, thus
we shouldn't call of_node_put unconditionally. Right?

(Sorry for reply late)

so 
then it's *only* the device references we'd need to worry about
cleaning 
up in the failure path.

Robin.

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