On Tue, Mar 15, 2022 at 01:25:31AM +0100, Tobias Waldekranz wrote:

Make it possible to change the port state in a given MSTI by extending
the bridge port netlink interface (RTM_SETLINK on PF_BRIDGE).The
proposed iproute2 interface would be:

    bridge mst set dev <PORT> msti <MSTI> state <STATE>

Current states in all applicable MSTIs can also be dumped via a
corresponding RTM_GETLINK. The proposed iproute interface looks like
this:

$ bridge mst
port              msti
vb1               0
		    state forwarding
		  100
		    state disabled
vb2               0
		    state forwarding
		  100
		    state forwarding

The preexisting per-VLAN states are still valid in the MST
mode (although they are read-only), and can be queried as usual if one
is interested in knowing a particular VLAN's state without having to
care about the VID to MSTI mapping (in this example VLAN 20 and 30 are
bound to MSTI 100):

$ bridge -d vlan
port              vlan-id
vb1               10
		    state forwarding mcast_router 1
		  20
		    state disabled mcast_router 1
		  30
		    state disabled mcast_router 1
		  40
		    state forwarding mcast_router 1
vb2               10
		    state forwarding mcast_router 1
		  20
		    state forwarding mcast_router 1
		  30
		    state forwarding mcast_router 1
		  40
		    state forwarding mcast_router 1

Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com>
---
+static int br_mst_process_one(struct net_bridge_port *p,
+			      const struct nlattr *attr,
+			      struct netlink_ext_ack *extack)
+{
+	struct nlattr *tb[IFLA_BRIDGE_MST_ENTRY_MAX + 1];
+	u16 msti;
+	u8 state;
+	int err;
+
+	err = nla_parse_nested(tb, IFLA_BRIDGE_MST_ENTRY_MAX, attr,
+			       br_mst_nl_policy, extack);
+	if (err)
+		return err;
+
+	if (!tb[IFLA_BRIDGE_MST_ENTRY_MSTI]) {
+		NL_SET_ERR_MSG_MOD(extack, "MSTI not specified");
+		return -EINVAL;
+	}
+
+	if (!tb[IFLA_BRIDGE_MST_ENTRY_STATE]) {
+		NL_SET_ERR_MSG_MOD(extack, "State not specified");
+		return -EINVAL;
+	}
+
+	msti = nla_get_u16(tb[IFLA_BRIDGE_MST_ENTRY_MSTI]);
+	state = nla_get_u8(tb[IFLA_BRIDGE_MST_ENTRY_STATE]);
+
+	br_mst_set_state(p, msti, state);

Is there any reason why this isn't propagating the error?

+	return 0;
+}