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phy: fix of_mdio_find_bus() device refcount leak

Browse Source 
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: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Russell King 2015-09-24 20:35:52 +01:00 committed by David S. Miller
parent 17a10c9215
commit a136442131
2 changed files with 16 additions and 7 deletions
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19
drivers/net/phy/mdio-mux.c
View File

@ -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);

4
drivers/net/phy/mdio_bus.c
View File

@ -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