SWITCHDEV_ATTR_ID_PORT_PARENT_ID is used by the software bridge when determining which ports to flood a packet out. If the packet originated from a switch, it assumes the switch has already flooded the packet out the switches ports, so the bridge should not flood the packet itself out switch ports. Ports on the same switch are expected to return the same parent ID when SWITCHDEV_ATTR_ID_PORT_PARENT_ID is called.
DSA gets this wrong with clusters of switches. As far as the software bridge is concerned, the cluster is all one switch. A packet from any switch in the cluster can be assumed to of been flooded as needed out all ports of the cluster, not just the switch it originated from. Hence all ports of a cluster should return the same parent. The old implementation did not, each switch in the cluster had its own ID. Also wrong was that the ID was not unique if multiple DSA instances are in operation. Use the MAC address of the master interface as the parent ID. This is the same for all switches in a cluster, and should be unique if there are multiple clusters. Signed-off-by: Andrew Lunn <and...@lunn.ch> --- net/dsa/slave.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/net/dsa/slave.c b/net/dsa/slave.c index 2e07be149415..d2744b0dad6e 100644 --- a/net/dsa/slave.c +++ b/net/dsa/slave.c @@ -374,13 +374,15 @@ static int dsa_slave_port_attr_get(struct net_device *dev, struct switchdev_attr *attr) { struct dsa_slave_priv *p = netdev_priv(dev); - struct dsa_switch *ds = p->dp->ds; switch (attr->id) { - case SWITCHDEV_ATTR_ID_PORT_PARENT_ID: - attr->u.ppid.id_len = sizeof(ds->index); - memcpy(&attr->u.ppid.id, &ds->index, attr->u.ppid.id_len); + case SWITCHDEV_ATTR_ID_PORT_PARENT_ID: { + struct net_device *master = dsa_master_netdev(p); + + attr->u.ppid.id_len = ETH_ALEN; + ether_addr_copy(attr->u.ppid.id, master->dev_addr); break; + } case SWITCHDEV_ATTR_ID_PORT_BRIDGE_FLAGS_SUPPORT: attr->u.brport_flags_support = 0; break; -- 2.14.1