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mdio: mux: Correct mdio_mux_init error path issues

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There is a potential unnecessary refcount decrement on error path of
put_device(&pb->mii_bus->dev), as it is possible to avoid the
of_mdio_find_bus() call if mux_bus is specified by the calling function.

The same put_device() is not called in the error path if the
devm_kzalloc of pb fails.  This caused the variable used in the
put_device() to be changed, as the pb pointer was obviously not set up.

There is an unnecessary of_node_get() on child_bus_node if the
of_mdiobus_register() is successful, as the
for_each_available_child_of_node() automatically increments this.
Thus the refcount on this node will always be +1 more than it should be.

There is no of_node_put() on child_bus_node if the of_mdiobus_register()
call fails.

Finally, it is lacking devm_kfree() of pb in the error path.  While this
might not be technically necessary, it was present in other parts of the
function.  So, I am adding it where necessary to make it uniform.

Signed-off-by: Jon Mason <jon.mason@broadcom.com>
Fixes: f20e6657a8 ("mdio: mux: Enhanced MDIO mux framework for integrated multiplexers")
Fixes: 0ca2997d14 ("netdev/of/phy: Add MDIO bus multiplexer support.")
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jon Mason 2017-05-10 11:20:27 -04:00 committed by David S. Miller
parent 83eaddab43
commit b601616681
1 changed files with 7 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
drivers/net/phy/mdio-mux.c
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@ -122,10 +122,9 @@ int mdio_mux_init(struct device *dev,
pb = devm_kzalloc(dev, sizeof(*pb), GFP_KERNEL);
if (pb == NULL) {
ret_val = -ENOMEM;
goto err_parent_bus;
goto err_pb_kz;
}
pb->switch_data = data;
pb->switch_fn = switch_fn;
pb->current_child = -1;
@ -154,6 +153,7 @@ int mdio_mux_init(struct device *dev,
cb->mii_bus = mdiobus_alloc();
if (!cb->mii_bus) {
ret_val = -ENOMEM;
devm_kfree(dev, cb);
of_node_put(child_bus_node);
break;
}
@ -169,8 +169,8 @@ int mdio_mux_init(struct device *dev,
if (r) {
mdiobus_free(cb->mii_bus);
devm_kfree(dev, cb);
of_node_put(child_bus_node);
} else {
of_node_get(child_bus_node);
cb->next = pb->children;
pb->children = cb;
}
@ -181,9 +181,11 @@ int mdio_mux_init(struct device *dev,
return 0;
}
devm_kfree(dev, pb);
err_pb_kz:
/* balance the reference of_mdio_find_bus() took */
put_device(&pb->mii_bus->dev);
if (!mux_bus)
put_device(&parent_bus->dev);
err_parent_bus:
of_node_put(parent_bus_node);
return ret_val;