Re: [PATCH v5 net-next 01/15] net: bridge: mst: Multiple Spanning Tree (MST) mode

[Vladimir Oltean]

On Mon, Jan 09, 2023 at 01:43:46PM +0200, Ido Schimmel wrote:
> OK, thanks for confirming. Will send a patch later this week if Tobias
> won't take care of it by then. First patch will probably be [1] to make
> sure we dump the correct MST state to user space. It will also make it
> easier to show the problem and validate the fix.
> 
> [1]
> diff --git a/net/bridge/br.c b/net/bridge/br.c
> index 4f5098d33a46..f02a1ad589de 100644
> --- a/net/bridge/br.c
> +++ b/net/bridge/br.c
> @@ -286,7 +286,7 @@ int br_boolopt_get(const struct net_bridge *br, enum br_boolopt_id opt)
>  	case BR_BOOLOPT_MCAST_VLAN_SNOOPING:
>  		return br_opt_get(br, BROPT_MCAST_VLAN_SNOOPING_ENABLED);
>  	case BR_BOOLOPT_MST_ENABLE:
> -		return br_opt_get(br, BROPT_MST_ENABLED);
> +		return br_mst_is_enabled(br);

Well, this did report the correct MST state despite the incorrect static
branch state, no? The users of br_mst_is_enabled(br) are broken, not
those of br_opt_get(br, BROPT_MST_ENABLED).

Anyway, I see there's a br_mst_is_enabled() and also a br_mst_enabled()?!
One is used in the fast path and the other in the slow path. They should
probably be merged, I guess. They both exist probably because somebody
thought that the "if (!netif_is_bridge_master(dev))" test is redundant
in the fast path.

>  	default:
>  		/* shouldn't be called with unsupported options */
>  		WARN_ON(1);
> diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
> index 75aff9bbf17e..7f0475f62d45 100644
> --- a/net/bridge/br_private.h
> +++ b/net/bridge/br_private.h
> @@ -1827,7 +1827,7 @@ static inline bool br_vlan_state_allowed(u8 state, bool learn_allow)
>  /* br_mst.c */
>  #ifdef CONFIG_BRIDGE_VLAN_FILTERING
>  DECLARE_STATIC_KEY_FALSE(br_mst_used);
> -static inline bool br_mst_is_enabled(struct net_bridge *br)
> +static inline bool br_mst_is_enabled(const struct net_bridge *br)
>  {
>  	return static_branch_unlikely(&br_mst_used) &&
>  		br_opt_get(br, BROPT_MST_ENABLED);
> @@ -1845,7 +1845,7 @@ int br_mst_fill_info(struct sk_buff *skb,
>  int br_mst_process(struct net_bridge_port *p, const struct nlattr *mst_attr,
>  		   struct netlink_ext_ack *extack);
>  #else
> -static inline bool br_mst_is_enabled(struct net_bridge *br)
> +static inline bool br_mst_is_enabled(const struct net_bridge *br)
>  {
>  	return false;
>  }