[PATCH 6.0 064/124] net: mdiobus: fix unbalanced node reference count

Greg Kroah-Hartman
2022-12-05T19:26:50Z

From: Yang Yingliang <yangyingliang@huawei.com>

[ Upstream commit cdde1560118f82498fc9e9a7c1ef7f0ef7755891 ]

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@0/mdio@7107009c/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@huawei.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/20221124150130.609420-1-yangyingliang@huawei.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 1c1584fca632..40e745a1d185 100644
--- a/drivers/net/mdio/fwnode_mdio.c
+++ b/drivers/net/mdio/fwnode_mdio.c
@@ -120,7 +120,7 @@ int fwnode_mdiobus_register_phy(struct mii_bus *bus,
/* 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);
diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 70c4d48f32c6..3607077cf86f 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -216,6 +216,7 @@ static void phy_mdio_device_free(struct mdio_device *mdiodev)

static void phy_device_release(struct device *dev)
{
+ fwnode_handle_put(dev->fwnode);
kfree(to_phy_device(dev));
}

--
2.35.1