Re: [PATCH v3] usb: roles: fix of node refcount leak in usb_role_switch_is_parent()

[Yang Yingliang <yangyingliang@huawei.com>]

On 2022/11/22 16:33, Heikki Krogerus wrote:
> Hi,
>
> On Mon, Nov 21, 2022 at 10:46:20PM +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")
>> Suggested-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> That's not the appropriate tag in this case. I have not suggested
> this patch.
>
>> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
>> ---
>> v2 -> v3:
>>    Remove not needed null pointer check.
>>
>> v1 -> v2:
>>    Add description to how is the report generated.
>> ---
>>   drivers/usb/roles/class.c | 5 ++++-
>>   1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/usb/roles/class.c b/drivers/usb/roles/class.c
>> index dfaed7eee94f..0650295f261c 100644
>> --- a/drivers/usb/roles/class.c
>> +++ b/drivers/usb/roles/class.c
>> @@ -106,10 +106,13 @@ 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")) {
> Please change that as well like I proposed earlier:
>
> 	if (!fwnode_property_present(parent, "usb-role-switch")) {
>
> You don't need to check the parent separately.
Yes, fwnode_property_present() has already checked the parent, the 
parent check can be removed.
Need I add your suggest tag when I send v4 to change it as above.

Thanks,
Yang
>
>> +		fwnode_handle_put(parent);
>>   		return NULL;
>> +	}
>>   
>>   	dev = class_find_device_by_fwnode(role_class, parent);
>> +	fwnode_handle_put(parent);
>>   	return dev ? to_role_switch(dev) : ERR_PTR(-EPROBE_DEFER);
>>   }
>>   
> thanks,
>