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

[Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>]

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@xxxxxxxxxx>
> > ---
> > 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;
        }

> >  	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,

-- 
heikki