Subject: [PATCH net-next 1/1] veth: Support bonding events

From: Alexandra Winter <[email-masked]>
Date: Mon, 28 Mar 2022 10:14:17 +0200

Bonding drivers generate specific events during failover that trigger
switch updates.  When a veth device is attached to a bridge with a
bond interface, we want external switches to learn about the veth
devices as well.

Signed-off-by: Alexandra Winter <[email-masked]>
---
 drivers/net/veth.c | 53 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 53 insertions(+)

diff --git a/drivers/net/veth.c b/drivers/net/veth.c
index d29fb9759cc9..9019c9852daf 100644
--- a/drivers/net/veth.c
+++ b/drivers/net/veth.c
@@ -1579,6 +1579,57 @@ static void veth_setup(struct net_device *dev)
 	dev->mpls_features = NETIF_F_HW_CSUM | NETIF_F_GSO_SOFTWARE;
 }
 
+static bool _is_veth(const struct net_device *dev)
+{
+	return (dev->netdev_ops->ndo_open == veth_open);
+}
+
+static void veth_notify_peer(unsigned long event, const struct net_device *dev)
+{
+	struct net_device *peer;
+	struct veth_priv *priv;
+
+	priv = netdev_priv(dev);
+	peer = rtnl_dereference(priv->peer);
+	/* avoid re-bounce between 2 bridges */
+	if (!netif_is_bridge_port(peer))
+		call_netdevice_notifiers(event, peer);
+}
+
+/* Called under rtnl_lock */
+static int veth_device_event(struct notifier_block *unused,
+			     unsigned long event, void *ptr)
+{
+	struct net_device *dev, *lower;
+	struct list_head *iter;
+
+	dev = netdev_notifier_info_to_dev(ptr);
+
+	switch (event) {
+	case NETDEV_NOTIFY_PEERS:
+	case NETDEV_BONDING_FAILOVER:
+	case NETDEV_RESEND_IGMP:
+		/* propagate to peer of a bridge attached veth */
+		if (netif_is_bridge_master(dev)) {
+			iter = &dev->adj_list.lower;
+			lower = netdev_next_lower_dev_rcu(dev, &iter);
+			while (lower) {
+				if (_is_veth(lower))
+					veth_notify_peer(event, lower);
+				lower = netdev_next_lower_dev_rcu(dev, &iter);
+			}
+		}
+		break;
+	default:
+		break;
+	}
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block veth_notifier_block __read_mostly = {
+		.notifier_call  = veth_device_event,
+};
+
 /*
  * netlink interface
  */
@@ -1824,12 +1875,14 @@ static struct rtnl_link_ops veth_link_ops = {
 
 static __init int veth_init(void)
 {
+	register_netdevice_notifier(&veth_notifier_block);
 	return rtnl_link_register(&veth_link_ops);
 }
 
 static __exit void veth_exit(void)
 {
 	rtnl_link_unregister(&veth_link_ops);
+	unregister_netdevice_notifier(&veth_notifier_block);
 }
 
 module_init(veth_init);
-- 
2.32.0