Re: [net-next v2 11/11] net: bridge: mcast: export multicast router presence adjacent to a port

On 09/05/2021 22:45, Linus Lüssing wrote:

To properly support routable multicast addresses in batman-adv in a group-aware way, a batman-adv node needs to know if it serves multicast routers.

This adds a function to the bridge to export this so that batman-adv can then make full use of the Multicast Router Discovery capability of the bridge.

Signed-off-by: Linus Lüssing linus.luessing@c0d3.blue

net/bridge/br_multicast.c | 58 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 58 insertions(+)

diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c index b625fd6..e963de5 100644 --- a/net/bridge/br_multicast.c +++ b/net/bridge/br_multicast.c @@ -4061,6 +4061,64 @@ unlock: } EXPORT_SYMBOL_GPL(br_multicast_has_querier_adjacent);

+/**

• • br_multicast_has_router_adjacent - Checks for a router behind a bridge port
• • @dev: The bridge port adjacent to which to check for a multicast router
• • @proto: The protocol family to check for: IGMP -> ETH_P_IP, MLD -> ETH_P_IPV6
• • Checks whether the given interface has a bridge on top and if so returns
• • true if a multicast router is behind one of the other ports of this
• • bridge. Otherwise returns false.
• */

+bool br_multicast_has_router_adjacent(struct net_device *dev, int proto) +{

• struct net_bridge_port *port, *p;
• bool ret = false;
• rcu_read_lock();
• if (!netif_is_bridge_port(dev))

• goto unlock;
  

• port = br_port_get_rcu(dev);

You can combine both of netif_is_bridge_port and br_port_get_rcu() checks and use br_port_get_check_rcu(). Then you can also drop the port->br check.

• if (!port || !port->br)

• goto unlock;
  

• switch (proto) {
• case ETH_P_IP:

• hlist_for_each_entry_rcu(p, &port->br->ip4_mc_router_list,
  

• 			 ip4_rlist) {
  

• 	if (p == port)
  

• 		continue;
  

• 	ret = true;
  

• 	goto unlock;
  

• }
  

• break;
  

+#if IS_ENABLED(CONFIG_IPV6)

• case ETH_P_IPV6:

• hlist_for_each_entry_rcu(p, &port->br->ip6_mc_router_list,
  

• 			 ip6_rlist) {
  

• 	if (p == port)
  

• 		continue;
  

• 	ret = true;
  

• 	goto unlock;
  

• }
  

• break;
  

+#endif

• default:

• /* when compiled without IPv6 support, be conservative and
  

•  * always assume presence of an IPv6 multicast router
  

•  */
  

• ret = true;
  

• }

+unlock:

• rcu_read_unlock();
• return ret;

+} +EXPORT_SYMBOL_GPL(br_multicast_has_router_adjacent);

static void br_mcast_stats_add(struct bridge_mcast_stats __percpu *stats, const struct sk_buff *skb, u8 type, u8 dir) {