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Commit a1364421 authored by Russell King's avatar Russell King Committed by David S. Miller
Browse files

phy: fix of_mdio_find_bus() device refcount leak 



of_mdio_find_bus() leaks a struct device refcount, caused by using
class_find_device() and not realising that the device reference has
its refcount incremented:

 * Note, you will need to drop the reference with put_device() after use.
...
        while ((dev = class_dev_iter_next(&iter))) {
                if (match(dev, data)) {
                        get_device(dev);
                        break;
                }

Update the comment, and arrange for the phy code to drop this refcount
when disposing of a reference to it.

Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 17a10c92

drivers/net/phy/mdio-mux.c

+13 −6
Original line number Diff line number Diff line
@@ -113,18 +113,18 @@ int mdio_mux_init(struct device *dev, 
	if (!parent_bus_node)

		return -ENODEV;



	parent_bus = of_mdio_find_bus(parent_bus_node);

	if (parent_bus == NULL) {

		ret_val = -EPROBE_DEFER;

		goto err_parent_bus;

	}



	pb = devm_kzalloc(dev, sizeof(*pb), GFP_KERNEL);

	if (pb == NULL) {

		ret_val = -ENOMEM;

		goto err_parent_bus;

	}



	parent_bus = of_mdio_find_bus(parent_bus_node);

	if (parent_bus == NULL) {

		ret_val = -EPROBE_DEFER;

		goto err_parent_bus;

	}



	pb->switch_data = data;

	pb->switch_fn = switch_fn;

	pb->current_child = -1;
@@ -173,6 +173,10 @@ int mdio_mux_init(struct device *dev, 
		dev_info(dev, "Version " DRV_VERSION "\n");

		return 0;

	}



	/* balance the reference of_mdio_find_bus() took */

	put_device(&pb->mii_bus->dev);



err_parent_bus:

	of_node_put(parent_bus_node);

	return ret_val;
@@ -189,6 +193,9 @@ void mdio_mux_uninit(void *mux_handle) 
		mdiobus_free(cb->mii_bus);

		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);

drivers/net/phy/mdio_bus.c

+3 −1
Original line number Diff line number Diff line
@@ -167,7 +167,9 @@ static int of_mdio_bus_match(struct device *dev, const void *mdio_bus_np) 
 * of_mdio_find_bus - Given an mii_bus node, find the mii_bus.

 * @mdio_bus_np: Pointer to the mii_bus.

 *

 * Returns a pointer to the mii_bus, or NULL if none found.

 * Returns a reference to the mii_bus, or NULL if none found.  The

 * embedded struct device will have its reference count incremented,

 * and this must be put once the bus is finished with.

 *

 * Because the association of a device_node and mii_bus is made via

 * of_mdiobus_register(), the mii_bus cannot be found before it is