Re: [PATCH v2 net-next 01/10] net: bridge: mst: Multiple Spanning Tree (MST) mode

[Vladimir Oltean]

On Tue, Mar 01, 2022 at 11:03:12AM +0100, Tobias Waldekranz wrote:
> Allow the user to switch from the current per-VLAN STP mode to an MST
> mode.
> 
> Up to this point, per-VLAN STP states where always isolated from each
> other. This is in contrast to the MSTP standard (802.1Q-2018, Clause
> 13.5), where VLANs are grouped into MST instances (MSTIs), and the
> state is managed on a per-MSTI level, rather that at the per-VLAN
> level.
> 
> Perhaps due to the prevalence of the standard, many switching ASICs
> are built after the same model. Therefore, add a corresponding MST
> mode to the bridge, which we can later add offloading support for in a
> straight-forward way.
> 
> For now, all VLANs are fixed to MSTI 0, also called the Common
> Spanning Tree (CST). That is, all VLANs will follow the port-global
> state.
> 
> Upcoming changes will make this actually useful by allowing VLANs to
> be mapped to arbitrary MSTIs and allow individual MSTI states to be
> changed.
> 
> Signed-off-by: Tobias Waldekranz <tobias@xxxxxxxxxxxxxx>
> ---
> +void br_mst_vlan_set_state(struct net_bridge_port *p, struct net_bridge_vlan *v,
> +			   u8 state)

Function can be static.

> +{
> +	struct net_bridge_vlan_group *vg = nbp_vlan_group(p);
> +
> +	if (v->state == state)
> +		return;
> +
> +	br_vlan_set_state(v, state);
> +
> +	if (v->vid == vg->pvid)
> +		br_vlan_set_pvid_state(vg, state);
> +}