[PATCH] net: dsa: microchip: drop the parent MDIO bus reference

[PATCH] net: dsa: microchip: drop the parent MDIO bus reference

[Wentao Liang]

ksz_mdio_register() obtains the parent MDIO bus with of_mdio_find_bus(),
which takes a reference on the embedded struct device, and stores it in
dev->parent_mdio_bus for the side MDIO accessors.  Nothing ever drops
that reference, so it is leaked on the probe error paths and when the
switch device is torn down.

Register a devres action to put the device when the DSA switch device
is released.  The child MDIO bus is unregistered before the action
runs, so the parent bus stays valid for the whole lifetime of the
switch.

Fixes: 9afaf0eec2ab ("net: dsa: microchip: Refactor MDIO handling for side MDIO access")
Cc: stable@vger.kernel.org
Assisted-by: DeepSeek-V4.1-Flash and OpenAI Codex
Signed-off-by: Wentao Liang <vulab@iscas.ac.cn>
---
 drivers/net/dsa/microchip/ksz_common.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/drivers/net/dsa/microchip/ksz_common.c b/drivers/net/dsa/microchip/ksz_common.c
index 767c8fe8e819..ddd821fa0d3e 100644
--- a/drivers/net/dsa/microchip/ksz_common.c
+++ b/drivers/net/dsa/microchip/ksz_common.c
@@ -2392,6 +2392,17 @@ int ksz_parse_dt_phy_config(struct ksz_device *dev, struct mii_bus *bus,
 	return 0;
 }
 
+/**
+ * ksz_mdio_put_parent_bus - Drop the reference on a parent MDIO bus
+ * @data: mii_bus obtained from of_mdio_find_bus()
+ */
+static void ksz_mdio_put_parent_bus(void *data)
+{
+	struct mii_bus *bus = data;
+
+	put_device(&bus->dev);
+}
+
 /**
  * ksz_mdio_register - Register and configure the MDIO bus for the KSZ device.
  * @dev: Pointer to the KSZ device structure.
@@ -2431,6 +2442,12 @@ int ksz_mdio_register(struct ksz_device *dev)
 			goto put_mdio_node;
 		}
 
+		ret = devm_add_action_or_reset(ds->dev,
+					       ksz_mdio_put_parent_bus,
+					       parent_bus);
+		if (ret)
+			goto put_mdio_node;
+
 		dev->parent_mdio_bus = parent_bus;
 	}
 
-- 
2.34.1

Re: [PATCH] net: dsa: microchip: drop the parent MDIO bus reference

[netdev-bot+sinfo]

Hi!

This is an automated message. This series looks like a fix, but its
commit messages seem to be missing some information:

 - How the issue was discovered, e.g. hit in production, hit during
   development, syzbot report, manual code inspection, LLM or static
   analysis tool scan.

 - Whether the issue was actually triggered, or is only theoretical
   (e.g. found by code inspection). If it was triggered please include
   the symptoms, like the stack trace or error messages.

Please do not repost the series just to address the above. Instead,
reply to this email with the missing information, so that reviewers
can take it into account. If the series needs another revision for
other reasons, please include the information in the commit messages
then.

The evaluation is done by an LLM so it may be wrong, if you think
that is the case please reply and explain.

Re: [PATCH] net: dsa: microchip: drop the parent MDIO bus reference

[Krzysztof Kozlowski]

On Tue, 03 Nov 2026 10:05:31 +0000, Wentao Liang wrote:
> ksz_mdio_register() obtains the parent MDIO bus with of_mdio_find_bus(),
> which takes a reference on the embedded struct device, and stores it in
> dev->parent_mdio_bus for the side MDIO accessors.  Nothing ever drops
> that reference, so it is leaked on the probe error paths and when the
> switch device is torn down.
> 
> Register a devres action to put the device when the DSA switch device
> is released.  The child MDIO bus is unregistered before the action
> runs, so the parent bus stays valid for the whole lifetime of the
> switch.
> 
> Fixes: 9afaf0eec2ab ("net: dsa: microchip: Refactor MDIO handling for side MDIO access")
> Cc: stable@vger.kernel.org
> Assisted-by: DeepSeek-V4.1-Flash and OpenAI Codex
> Signed-off-by: Wentao Liang <vulab@iscas.ac.cn>
> ---
>  drivers/net/dsa/microchip/ksz_common.c | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
> 



Multiple things here:
1. Your team ignored completely previous feedback. Multiple times.

2. You use multiple identities with this email address, thus I doubt that we
   speak with an actual person.

3. Your bot does not even bother running checkpatch, right?

4. Nothing of this was reproduced nor tested.

5. Finally, the same feedback:
You sent multiple independent patches, to multiple independent
subsystems. The amount of these patches clearly suggest this was
AI generated and most likely not tested.

More importantly, you sent all this work without properly organizing
relevant patches into patchsets. This makes reviewing difficult
and might cause multiple reviewers to address the same issue.
Replying to the entire set is impossible and requires handling each
patch independently, instead of applying or discarding the set.
Maintainers also won't see the bigger picture of your work. Quite
worrying.

This is on the verge of hostile patch: bomb us with so many
contributions, we won't be able to handle them in efficient manner,
like responding ONCE to ask you to slow down.  Considering all this
is untested and LLM generated, I have even more doubts whether this
should be considered for review.

Please read kernel documentation BEFORE posting more work. It will
explain you how to identify subsystems, how to organize your work per
subsystem (so a patchset grouping multiple patches with a short cover
letter), how to document the issue discovery method and what was
or was not tested.

Best regards,
Krzysztof