net: mdio-mux: fix unbalanced put_device

commit 60f786525032432af1b7d9b8935cb12936244ccd upstream.

mdio_mux_uninit() call put_device (unconditionally) because of
of_mdio_find_bus() in mdio_mux_init.
But of_mdio_find_bus is only called if mux_bus is empty.
If mux_bus is set, mdio_mux_uninit will print a "refcount_t: underflow"
trace.

This patch add a get_device in the other branch of "if (mux_bus)".

Signed-off-by: Corentin Labbe <clabbe.montjoie@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/net/phy/mdio-mux.c b/drivers/net/phy/mdio-mux.c
index 599ce24c514f1b0eb1e8a6df1e3a0362f53bee26..456b64248e5daf6440ac0ef4d8697253215f4b72 100644 (file)
--- a/drivers/net/phy/mdio-mux.c
+++ b/drivers/net/phy/mdio-mux.c
@@ -117,6 +117,7 @@ int mdio_mux_init(struct device *dev,
        } else {
                parent_bus_node = NULL;
                parent_bus = mux_bus;
+               get_device(&parent_bus->dev);
        }
 
        pb = devm_kzalloc(dev, sizeof(*pb), GFP_KERNEL);
@@ -182,9 +183,7 @@ int mdio_mux_init(struct device *dev,
 
        devm_kfree(dev, pb);
 err_pb_kz:
-       /* balance the reference of_mdio_find_bus() took */
-       if (!mux_bus)
-               put_device(&parent_bus->dev);
+       put_device(&parent_bus->dev);
 err_parent_bus:
        of_node_put(parent_bus_node);
        return ret_val;
@@ -202,7 +201,6 @@ void mdio_mux_uninit(void *mux_handle)
                cb = cb->next;
        }
 
-       /* balance the reference of_mdio_find_bus() in mdio_mux_init() took */
        put_device(&pb->mii_bus->dev);
 }
 EXPORT_SYMBOL_GPL(mdio_mux_uninit);