Re: [PATCH net-next v2 0/3] switchdev: support stp updates on stacked netdevices

On Fri, Mar 13, 2015 at 9:31 AM, David Miller [off-list ref] wrote:

From: roopa <redacted>
Date: Fri, 13 Mar 2015 06:25:24 -0700

quoted

David, if you mean not touch bond and team but have the switchdev
api do it transparently, yes, i had it that way initially.  And i do
liked it that way as well. But the feedback i received (during the
initial introduction of this for setlink/dellink) was to make it
explicit for each master.

I think the concern is that we only want to do this for devices
for which it is safe to "traverse" down like this.

But frankly I cannot think of any layered device where we would
not want to do this.

Let's go back to the simple scheme where we unconditionally traverse
and if we hit a problem case we'll figure out how to deal with it
then, ok?

Here's a way to do it without touching team/bonding/vlan drivers, but
also giving us flexibility to down the road to intercept the call in
the team/bonding/vlan driver and change the behavior by implementing
swdev_port_stp_update in the middle driver.

I would prefer this approach not only for STP updates but also for
port attr set/get calls.


/**
 *      netdev_switch_port_stp_update - Notify switch device port of STP
 *                                      state change
 *      @dev: bridge port device
 *      @state: bridge port STP state
 *
 *      Notify switch device port of bridge port STP state change.
 */
int netdev_switch_port_stp_update(struct net_device *dev, u8 state)
{
        const struct swdev_ops *ops = dev->swdev_ops;
        struct net_device *lower_dev;
        struct list_head *iter;
        int err = -EOPNOTSUPP;

        if (ops && ops->swdev_port_stp_update)
                return ops->swdev_port_stp_update(dev, state);

        /* Bridged switch device port(s) may be stacked under
         * bond/team/vlan dev, so recurse down to stp-update
         * them one at a time.
         */

        netdev_for_each_lower_dev(dev, lower_dev, iter) {
                err = netdev_switch_port_stp_update(lower_dev, state);
                if (err && err != -EOPNOTSUPP)
                        return err;
        }

        return err;
}
EXPORT_SYMBOL_GPL(netdev_switch_port_stp_update);