Subject: Re: [RFC 1/3] net: switchdev: do not propagate bridge updates across bridges

From: Ido Schimmel <[email-masked]>
Date: Tue, 24 Dec 2019 10:39:31 +0200

On Sun, Dec 22, 2019 at 07:24:03PM +0000, Russell King wrote:
> When configuring a tree of independent bridges, propagating changes
> from the upper bridge across a bridge master to the lower bridge
> ports brings surprises.
> 
> For example, a lower bridge may have vlan filtering enabled.  It
> may have a vlan interface attached to the bridge master, which may
> then be incorporated into another bridge.  As soon as the lower
> bridge vlan interface is attached to the upper bridge, the lower
> bridge has vlan filtering disabled.

Interesting topology :) The change looks OK to me. I'll add the patch to
our internal tree and let it go through regression to make sure I didn't
miss anything. Will report the results tomorrow.

> 
> This occurs because switchdev recursively applies its changes to
> all lower devices no matter what.
> 
> Signed-off-by: Russell King <[email-masked]>
> ---
>  net/switchdev/switchdev.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/net/switchdev/switchdev.c b/net/switchdev/switchdev.c
> index 3a1d428c1336..d881e5e4a889 100644
> --- a/net/switchdev/switchdev.c
> +++ b/net/switchdev/switchdev.c
> @@ -475,6 +475,9 @@ static int __switchdev_handle_port_obj_add(struct net_device *dev,
>  	 * necessary to go through this helper.
>  	 */
>  	netdev_for_each_lower_dev(dev, lower_dev, iter) {
> +		if (netif_is_bridge_master(lower_dev))
> +			continue;
> +
>  		err = __switchdev_handle_port_obj_add(lower_dev, port_obj_info,
>  						      check_cb, add_cb);
>  		if (err && err != -EOPNOTSUPP)
> @@ -526,6 +529,9 @@ static int __switchdev_handle_port_obj_del(struct net_device *dev,
>  	 * necessary to go through this helper.
>  	 */
>  	netdev_for_each_lower_dev(dev, lower_dev, iter) {
> +		if (netif_is_bridge_master(lower_dev))
> +			continue;
> +
>  		err = __switchdev_handle_port_obj_del(lower_dev, port_obj_info,
>  						      check_cb, del_cb);
>  		if (err && err != -EOPNOTSUPP)
> @@ -576,6 +582,9 @@ static int __switchdev_handle_port_attr_set(struct net_device *dev,
>  	 * necessary to go through this helper.
>  	 */
>  	netdev_for_each_lower_dev(dev, lower_dev, iter) {
> +		if (netif_is_bridge_master(lower_dev))
> +			continue;
> +
>  		err = __switchdev_handle_port_attr_set(lower_dev, port_attr_info,
>  						       check_cb, set_cb);
>  		if (err && err != -EOPNOTSUPP)
> -- 
> 2.20.1
>