Re: [PATCH v2] usb: roles: fix of node refcount leak in usb_role_switch_is_parent()

[Yang Yingliang <yangyingliang@huawei.com>]

Hi,

On 2022/11/21 16:55, Heikki Krogerus wrote:
> Hi,
>
> On Mon, Nov 21, 2022 at 07:49:31AM +0000, Chunfeng Yun (云春峰) wrote:
>> On Sat, 2022-11-19 at 17:15 +0800, Yang Yingliang wrote:
>>> I got the following report while doing device(mt6370-tcpc) 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 /i2c/pmic@34
>>>
>>> The 'parent' returned by fwnode_get_parent() with refcount
>>> incremented.
>>> it needs be put after using.
>>>
>>> Fixes: 6fadd72943b8 ("usb: roles: get usb-role-switch from parent")
>>> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
>>> ---
>>> v1 -> v2:
>>>    Add description to how is the report generated.
>>> ---
>>>   drivers/usb/roles/class.c | 6 +++++-
>>>   1 file changed, 5 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/usb/roles/class.c b/drivers/usb/roles/class.c
>>> index dfaed7eee94f..289950e5fcfb 100644
>>> --- a/drivers/usb/roles/class.c
>>> +++ b/drivers/usb/roles/class.c
>>> @@ -106,10 +106,14 @@ usb_role_switch_is_parent(struct fwnode_handle
>>> *fwnode)
>>>   	struct fwnode_handle *parent = fwnode_get_parent(fwnode);
>>>   	struct device *dev;
>>>   
>>> -	if (!parent || !fwnode_property_present(parent, "usb-role-
>>> switch"))
>>> +	if (!parent || !fwnode_property_present(parent, "usb-role-
>>> switch")) {
>>> +		if (parent)
>>> +			fwnode_handle_put(parent);
>>>   		return NULL;
>>> +	}
> fwnode API should be NULL safe, so perhaps like this - clean also the
> old condition while at it:
>
>          if (!fwnode_property_present(parent, "usb-role-switch")) {
>                  fwnode_handle_put(parent);
>                  return NULL;
>          }
Thanks for your suggestion, I will send a v3 to change this.

Thanks,
Yang
>
>>>   	dev = class_find_device_by_fwnode(role_class, parent);
>>> +	fwnode_handle_put(parent);
>>>   	return dev ? to_role_switch(dev) : ERR_PTR(-EPROBE_DEFER);
>>>   }
>>>   
>> + Heikki
> Thanks Chunfeng!
>
> cheers,
>