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

Hello Manush,

Were you able to test this on real HW?

I am currently on a different code base and device (X5H). I have tested it with your original 
patch and with v2 of the patch. 

Patch v1 works fine; patch v2 does not work.

Best regards,

Michael

> -----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;
>  	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) {
> +		if (of_property_read_u32(child, "reg", &index))
> +			break;
> +		if (index == rdev->etha->index) {
> +			port = of_node_get(child);
>  			break;
> +		}
>  	}
> 
> -out:
>  	of_node_put(ports);
> 
>  	return port;
> --
> 2.46.2.windows.1