RE: [PATCH v2] net: ethernet: renesas: rswitch: fix device_node refcount leak in rswitch_get_port_node()

Hello Manush,

Here is an update on v2. I tested it on S4 hardware and it is working fine.

Best regards,

Michael

> -----Original Message-----
> From: Michael Dege <[email protected]>
> Sent: Monday, August 17, 2026 3:12 PM
> To: manushprajwal <[email protected]>; Yoshihiro Shimoda <[email protected]>
> Cc: Andrew Lunn <[email protected]>; [email protected]; Eric Dumazet <[email protected]>;
> Jakub Kicinski <[email protected]>; Paolo Abeni <[email protected]>; [email protected]; linux-
> [email protected]
> Subject: RE: [PATCH v2] net: ethernet: renesas: rswitch: fix device_node refcount leak in
> rswitch_get_port_node()
> 
> Hello Manush,
> 
> Besides the problem mentioned previously. The links on the interfaces do not come up.
> 
> > -----Original Message-----
> > From: manushprajwal <[email protected]>
> > Sent: Friday, August 14, 2026 9:04 PM
> > To: Yoshihiro Shimoda <[email protected]>
> > Cc: Andrew Lunn <[email protected]>; [email protected]; Eric
> > Dumazet <[email protected]>; Jakub Kicinski <[email protected]>; Paolo
> > Abeni <[email protected]>; [email protected]; linux-
> > [email protected]; Manush Prajwal
> > <[email protected]>
> > Subject: [PATCH v2] net: ethernet: renesas: rswitch: fix device_node
> > refcount leak in
> > rswitch_get_port_node()
> >
> > From: Manush Prajwal <[email protected]>
> >
> > On an of_property_read_u32() failure, rswitch_get_port_node() set port
> > to NULL and jumped to the out label before releasing the reference the
> > for_each_available_child_of_node() iterator was holding on it. Once
> > port was overwritten with NULL, that reference could never be released since out: only put "ports",
> the parent node.
> >
> > Rework the function around for_each_available_child_of_node_scoped()
> > instead of adding a manual of_node_put(), so the iterator's reference
> > is dropped automatically on every exit path. Since port is the
> > function's return value, take an explicit reference with
> > of_node_get() on the match before breaking out of the loop.
> >
> > Signed-off-by: Manush Prajwal <[email protected]>
> > ---
> > v2: Rework using for_each_available_child_of_node_scoped() instead of
> >     a manual of_node_put(), per Andrew Lunn's review.
> >
> >  drivers/net/ethernet/renesas/rswitch_main.c | 20 +++++++++-----------
> >  1 file changed, 9 insertions(+), 11 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/renesas/rswitch_main.c
> > b/drivers/net/ethernet/renesas/rswitch_main.c
> > index 6fe9648163..ffdc42f430 100644
> > --- a/drivers/net/ethernet/renesas/rswitch_main.c
> > +++ b/drivers/net/ethernet/renesas/rswitch_main.c
> > @@ -1303,8 +1303,8 @@
> >  /* Call of_node_put(port) after done */  static struct device_node
> > *rswitch_get_port_node(struct rswitch_device *rdev)  {
> > -	struct device_node *ports, *port;
> > -	int err = 0;
> > +	struct device_node *ports;
> > +	struct device_node *port = NULL;
> 
> Here you declare "port"
> >  	u32 index;
> >
> >  	ports = of_get_child_by_name(rdev->ndev->dev.parent->of_node,
> > @@ -1312,17 +1312,15 @@ static struct device_node *rswitch_get_port_node(struct rswitch_device
> *rdev)
> >  	if (!ports)
> >  		return NULL;
> >
> > -	for_each_available_child_of_node(ports, port) {
> > -		err = of_property_read_u32(port, "reg", &index);
> > -		if (err < 0) {
> > -			port = NULL;
> > -			goto out;
> > -		}
> > -		if (index == rdev->etha->index)
> > +	for_each_available_child_of_node_scoped(ports, child) {
> But here you  use child.
> 
> > +		if (of_property_read_u32(child, "reg", &index))
> 
> Same as above
> 
> > +			break;
> > +		if (index == rdev->etha->index) {
> > +			port = of_node_get(child);
> 
> Here too.
> 
> Best regards,
> 
> Michael
> 
> >  			break;
> > +		}
> >  	}
> >
> > -out:
> >  	of_node_put(ports);
> >
> >  	return port;
> > --
> > 2.46.2.windows.1
>