Re: [PATCH v4 net-next 03/15] net: bridge: mst: Support setting and reporting MST port states

[Vladimir Oltean <olteanv@gmail.com>]

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;
> +}