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

Message ID 20210509194509.10849-12-linus.luessing@c0d3.blue (mailing list archive)
State Superseded
Delegated to: Netdev Maintainers
Headers show
Series net: bridge: split IPv4/v6 mc router state and export for batman-adv | expand

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Commit Message

Linus Lüssing May 9, 2021, 7:45 p.m. UTC
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(+)

Comments

Nikolay Aleksandrov May 11, 2021, 9:23 a.m. UTC | #1
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)
>  {
>
diff mbox series

Patch

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);
+	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)
 {