netdev - [PATCH net] net: mdiobus: fix unbalanced node reference count

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Message-ID: <20221124150130.609420-1-yangyingliang@huawei.com>
Date:   Thu, 24 Nov 2022 23:01:30 +0800
From:   Yang Yingliang <yangyingliang@...wei.com>
To:     <netdev@...r.kernel.org>
CC:     <andrew@...n.ch>, <hkallweit1@...il.com>, <linux@...linux.org.uk>,
        <davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
        <pabeni@...hat.com>, <ioana.ciornei@....com>,
        <calvin.johnson@....nxp.com>, <grant.likely@....com>
Subject: [PATCH net] net: mdiobus: fix unbalanced node reference count

I got the following report while doing device(mscc-miim) load test
with CONFIG_OF_UNITTEST and CONFIG_OF_DYNAMIC enabled:

  OF: ERROR: memory leak, expected refcount 1 instead of 2,
  of_node_get()/of_node_put() unbalanced - destroy cset entry:
  attach overlay node /spi/soc@...dio@...7009c/ethernet-phy@0

If the 'fwnode' is not an acpi node, the refcount is get in
fwnode_mdiobus_phy_device_register(), but it has never been
put when the device is freed in the normal path. So call
fwnode_handle_put() in phy_device_release() to avoid leak.

If it's an acpi node, it has never been get, but it's put
in the error path, so call fwnode_handle_get() before
phy_device_register() to keep get/put operation balanced.

Fixes: bc1bee3b87ee ("net: mdiobus: Introduce fwnode_mdiobus_register_phy()")
Signed-off-by: Yang Yingliang <yangyingliang@...wei.com>
---
 drivers/net/mdio/fwnode_mdio.c | 2 +-
 drivers/net/phy/phy_device.c   | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/mdio/fwnode_mdio.c b/drivers/net/mdio/fwnode_mdio.c
index 689e728345ce..eb344f6d4a7b 100644
--- a/drivers/net/mdio/fwnode_mdio.c
+++ b/drivers/net/mdio/fwnode_mdio.c
@@ -146,11 +146,11 @@ int fwnode_mdiobus_register_phy(struct mii_bus *bus,
 		phy->irq = bus->irq[addr];
 
 		/* Associate the fwnode with the device structure so it
 		 * can be looked up later.
 		 */
-		phy->mdio.dev.fwnode = child;
+		phy->mdio.dev.fwnode = fwnode_handle_get(child);
 
 		/* All data is now stored in the phy struct, so register it */
 		rc = phy_device_register(phy);
 		if (rc) {
 			fwnode_handle_put(phy->mdio.dev.fwnode);
diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index a72adabfd2a7..8cff61dbc4b5 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -215,10 +215,11 @@ static void phy_mdio_device_free(struct mdio_device *mdiodev)
 	phy_device_free(phydev);
 }
 
 static void phy_device_release(struct device *dev)
 {
+	fwnode_handle_put(dev->fwnode);
 	kfree(to_phy_device(dev));
 }
 
 static void phy_mdio_device_remove(struct mdio_device *mdiodev)
 {
-- 
2.25.1