Linux Ethernet Bridging - May 2021 - [Bridge] [PATCH net-next v3 00/11] net: bridge: split IPv4/v6 mc router state and export for batman-adv

Hi,

The following patches are splitting the so far combined multicast router
state in the Linux bridge into two ones, one for IPv4 and one for IPv6,
for a more fine-grained detection of multicast routers. This avoids
sending IPv4 multicast packets to an IPv6-only multicast router and 
avoids sending IPv6 multicast packets to an IPv4-only multicast router.
This also allows batman-adv to make use of the now split information in
the final patch.

The first eight patches prepare the bridge code to avoid duplicate
code or IPv6-#ifdef clutter for the multicast router state split. And 
contain no functional changes yet.

The ninth patch then implements the IPv4+IPv6 multicast router state
split.

Patch number ten adds IPv4+IPv6 specific timers to the mdb netlink
router port dump, so that the timers validity can be checked individually
from userspace.

The final, eleventh patch exports this now per protocol family multicast
router state so that batman-adv can then later make full use of the 
Multicast Router Discovery (MRD) support in the Linux bridge. The 
batman-adv protocol format currently expects separate multicast router
states for IPv4 and IPv6, therefore it depends on the first patch.
batman-adv will then make use of this newly exported functions like
this[0].

Regards, Linus

[0]:
https://git.open-mesh.org/batman-adv.git/shortlog/refs/heads/linus/multicast-routeable-mrd
     ->
https://git.open-mesh.org/batman-adv.git/commit/d4bed3a92427445708baeb1f2d1841c5fb816fd4

Changelog v3:

* Patch 01/11:
  * fixed/added missing rename of br->router_list to
    br->ip4_mc_router_list in br_multicast_flood()
* Patch 02/11:
  * moved inline functions from br_forward.c to br_private.h
* Patch 03/11:
  * removed inline attribute from functions added to br_mdb.c
* Patch 04/11:
  * unchanged
* Patch 05/11:
  * converted if()'s into switch-case in br_multicast_is_router()
* Patch 06/11:
  * removed inline attribute from function added to br_multicast.c
* Patch 07/11:
  * added missing static attribute to function
    br_ip4_multicast_get_rport_slot() added to br_multicast.c
* Patch 08/11:
  * removed inline attribute from function added to br_multicast.c
* Patch 09/11:
  * added missing static attribute to function
    br_ip6_multicast_get_rport_slot() added to br_multicast.c
  * removed inline attribute from function added to br_multicast.c
* Patch 10/11:
  * unchanged
* Patch 11/11:
  * simplified bridge check in br_multicast_has_router_adjacent()
    by using br_port_get_check_rcu()
  * added missing declaration for br_multicast_has_router_adjacent()
    in include/linux/if_bridge.h

Changelog v2:

* split into multiple patches as suggested by Nikolay
* added helper functions to br_multicast_flood(), avoiding
  IPv6 #ifdef clutter
* fixed reverse xmas tree ordering in br_rports_fill_info() and
  added helper functions to avoid IPv6 #ifdef clutter
* Added a common br_multicast_add_router() and a helper function
  to retrieve the correct slot to avoid duplicate code for an
  ip4 and ip6 variant
* replaced the "1" and "2" constants in
br_multicast_is_router()
  with the appropriate enums
* added br_{ip4,ip6}_multicast_rport_del() wrappers to reduce
  IPv6 #ifdef clutter
* added return values to br_*multicast_rport_del() to only notify
  if the port was actually removed and did not race with a readdition
  somewhere else
* added empty, void br_ip6_multicast_mark_router() if compiled
  without IPv6, to reduce IPv6 #ifdef clutter

In preparation for the upcoming split of multicast router state into
their IPv4 and IPv6 variants, rename the affected variable to the IPv4
version first to avoid some renames in later commits.

Signed-off-by: Linus L?ssing <linus.luessing at c0d3.blue>
---
 net/bridge/br_forward.c   |  4 ++--
 net/bridge/br_mdb.c       |  6 ++---
 net/bridge/br_multicast.c | 48 +++++++++++++++++++--------------------
 net/bridge/br_private.h   | 10 ++++----
 4 files changed, 34 insertions(+), 34 deletions(-)

diff --git a/net/bridge/br_forward.c b/net/bridge/br_forward.c
index 6e9b049..eb9847a 100644
--- a/net/bridge/br_forward.c
+++ b/net/bridge/br_forward.c
@@ -276,7 +276,7 @@ void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
 	bool allow_mode_include = true;
 	struct hlist_node *rp;
 
-	rp = rcu_dereference(hlist_first_rcu(&br->router_list));
+	rp = rcu_dereference(hlist_first_rcu(&br->ip4_mc_router_list));
 	if (mdst) {
 		p = rcu_dereference(mdst->ports);
 		if (br_multicast_should_handle_mode(br, mdst->addr.proto) &&
@@ -290,7 +290,7 @@ void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
 		struct net_bridge_port *port, *lport, *rport;
 
 		lport = p ? p->key.port : NULL;
-		rport = hlist_entry_safe(rp, struct net_bridge_port, rlist);
+		rport = hlist_entry_safe(rp, struct net_bridge_port, ip4_rlist);
 
 		if ((unsigned long)lport > (unsigned long)rport) {
 			port = lport;
diff --git a/net/bridge/br_mdb.c b/net/bridge/br_mdb.c
index 95fa4af..d61def8 100644
--- a/net/bridge/br_mdb.c
+++ b/net/bridge/br_mdb.c
@@ -23,14 +23,14 @@ static int br_rports_fill_info(struct sk_buff *skb, struct
netlink_callback *cb,
 	struct net_bridge_port *p;
 	struct nlattr *nest, *port_nest;
 
-	if (!br->multicast_router || hlist_empty(&br->router_list))
+	if (!br->multicast_router || hlist_empty(&br->ip4_mc_router_list))
 		return 0;
 
 	nest = nla_nest_start_noflag(skb, MDBA_ROUTER);
 	if (nest == NULL)
 		return -EMSGSIZE;
 
-	hlist_for_each_entry_rcu(p, &br->router_list, rlist) {
+	hlist_for_each_entry_rcu(p, &br->ip4_mc_router_list, ip4_rlist) {
 		if (!p)
 			continue;
 		port_nest = nla_nest_start_noflag(skb, MDBA_ROUTER_PORT);
@@ -38,7 +38,7 @@ static int br_rports_fill_info(struct sk_buff *skb, struct
netlink_callback *cb,
 			goto fail;
 		if (nla_put_nohdr(skb, sizeof(u32), &p->dev->ifindex) ||
 		    nla_put_u32(skb, MDBA_ROUTER_PATTR_TIMER,
-				br_timer_value(&p->multicast_router_timer)) ||
+				br_timer_value(&p->ip4_mc_router_timer)) ||
 		    nla_put_u8(skb, MDBA_ROUTER_PATTR_TYPE,
 			       p->multicast_router)) {
 			nla_nest_cancel(skb, port_nest);
diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index 226bb05..6fe93a3 100644
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -1357,13 +1357,13 @@ static int br_ip6_multicast_add_group(struct net_bridge
*br,
 static void br_multicast_router_expired(struct timer_list *t)
 {
 	struct net_bridge_port *port -			from_timer(port, t, multicast_router_timer);
+			from_timer(port, t, ip4_mc_router_timer);
 	struct net_bridge *br = port->br;
 
 	spin_lock(&br->multicast_lock);
 	if (port->multicast_router == MDB_RTR_TYPE_DISABLED ||
 	    port->multicast_router == MDB_RTR_TYPE_PERM ||
-	    timer_pending(&port->multicast_router_timer))
+	    timer_pending(&port->ip4_mc_router_timer))
 		goto out;
 
 	__del_port_router(port);
@@ -1386,12 +1386,12 @@ static void br_mc_router_state_change(struct net_bridge
*p,
 
 static void br_multicast_local_router_expired(struct timer_list *t)
 {
-	struct net_bridge *br = from_timer(br, t, multicast_router_timer);
+	struct net_bridge *br = from_timer(br, t, ip4_mc_router_timer);
 
 	spin_lock(&br->multicast_lock);
 	if (br->multicast_router == MDB_RTR_TYPE_DISABLED ||
 	    br->multicast_router == MDB_RTR_TYPE_PERM ||
-	    timer_pending(&br->multicast_router_timer))
+	    timer_pending(&br->ip4_mc_router_timer))
 		goto out;
 
 	br_mc_router_state_change(br, false);
@@ -1613,7 +1613,7 @@ int br_multicast_add_port(struct net_bridge_port *port)
 	port->multicast_router = MDB_RTR_TYPE_TEMP_QUERY;
 	port->multicast_eht_hosts_limit = BR_MCAST_DEFAULT_EHT_HOSTS_LIMIT;
 
-	timer_setup(&port->multicast_router_timer,
+	timer_setup(&port->ip4_mc_router_timer,
 		    br_multicast_router_expired, 0);
 	timer_setup(&port->ip4_own_query.timer,
 		    br_ip4_multicast_port_query_expired, 0);
@@ -1649,7 +1649,7 @@ void br_multicast_del_port(struct net_bridge_port *port)
 	hlist_move_list(&br->mcast_gc_list, &deleted_head);
 	spin_unlock_bh(&br->multicast_lock);
 	br_multicast_gc(&deleted_head);
-	del_timer_sync(&port->multicast_router_timer);
+	del_timer_sync(&port->ip4_mc_router_timer);
 	free_percpu(port->mcast_stats);
 }
 
@@ -1674,7 +1674,7 @@ static void __br_multicast_enable_port(struct
net_bridge_port *port)
 	br_multicast_enable(&port->ip6_own_query);
 #endif
 	if (port->multicast_router == MDB_RTR_TYPE_PERM &&
-	    hlist_unhashed(&port->rlist))
+	    hlist_unhashed(&port->ip4_rlist))
 		br_multicast_add_router(br, port);
 }
 
@@ -1700,7 +1700,7 @@ void br_multicast_disable_port(struct net_bridge_port
*port)
 
 	__del_port_router(port);
 
-	del_timer(&port->multicast_router_timer);
+	del_timer(&port->ip4_mc_router_timer);
 	del_timer(&port->ip4_own_query.timer);
 #if IS_ENABLED(CONFIG_IPV6)
 	del_timer(&port->ip6_own_query.timer);
@@ -2666,19 +2666,19 @@ static void br_multicast_add_router(struct net_bridge
*br,
 	struct net_bridge_port *p;
 	struct hlist_node *slot = NULL;
 
-	if (!hlist_unhashed(&port->rlist))
+	if (!hlist_unhashed(&port->ip4_rlist))
 		return;
 
-	hlist_for_each_entry(p, &br->router_list, rlist) {
+	hlist_for_each_entry(p, &br->ip4_mc_router_list, ip4_rlist) {
 		if ((unsigned long) port >= (unsigned long) p)
 			break;
-		slot = &p->rlist;
+		slot = &p->ip4_rlist;
 	}
 
 	if (slot)
-		hlist_add_behind_rcu(&port->rlist, slot);
+		hlist_add_behind_rcu(&port->ip4_rlist, slot);
 	else
-		hlist_add_head_rcu(&port->rlist, &br->router_list);
+		hlist_add_head_rcu(&port->ip4_rlist, &br->ip4_mc_router_list);
 	br_rtr_notify(br->dev, port, RTM_NEWMDB);
 	br_port_mc_router_state_change(port, true);
 }
@@ -2690,9 +2690,9 @@ static void br_multicast_mark_router(struct net_bridge
*br,
 
 	if (!port) {
 		if (br->multicast_router == MDB_RTR_TYPE_TEMP_QUERY) {
-			if (!timer_pending(&br->multicast_router_timer))
+			if (!timer_pending(&br->ip4_mc_router_timer))
 				br_mc_router_state_change(br, true);
-			mod_timer(&br->multicast_router_timer,
+			mod_timer(&br->ip4_mc_router_timer,
 				  now + br->multicast_querier_interval);
 		}
 		return;
@@ -2704,7 +2704,7 @@ static void br_multicast_mark_router(struct net_bridge
*br,
 
 	br_multicast_add_router(br, port);
 
-	mod_timer(&port->multicast_router_timer,
+	mod_timer(&port->ip4_mc_router_timer,
 		  now + br->multicast_querier_interval);
 }
 
@@ -3316,7 +3316,7 @@ void br_multicast_init(struct net_bridge *br)
 	br_opt_toggle(br, BROPT_HAS_IPV6_ADDR, true);
 
 	spin_lock_init(&br->multicast_lock);
-	timer_setup(&br->multicast_router_timer,
+	timer_setup(&br->ip4_mc_router_timer,
 		    br_multicast_local_router_expired, 0);
 	timer_setup(&br->ip4_other_query.timer,
 		    br_ip4_multicast_querier_expired, 0);
@@ -3416,7 +3416,7 @@ void br_multicast_open(struct net_bridge *br)
 
 void br_multicast_stop(struct net_bridge *br)
 {
-	del_timer_sync(&br->multicast_router_timer);
+	del_timer_sync(&br->ip4_mc_router_timer);
 	del_timer_sync(&br->ip4_other_query.timer);
 	del_timer_sync(&br->ip4_own_query.timer);
 #if IS_ENABLED(CONFIG_IPV6)
@@ -3453,7 +3453,7 @@ int br_multicast_set_router(struct net_bridge *br,
unsigned long val)
 	case MDB_RTR_TYPE_DISABLED:
 	case MDB_RTR_TYPE_PERM:
 		br_mc_router_state_change(br, val == MDB_RTR_TYPE_PERM);
-		del_timer(&br->multicast_router_timer);
+		del_timer(&br->ip4_mc_router_timer);
 		br->multicast_router = val;
 		err = 0;
 		break;
@@ -3472,9 +3472,9 @@ int br_multicast_set_router(struct net_bridge *br,
unsigned long val)
 
 static void __del_port_router(struct net_bridge_port *p)
 {
-	if (hlist_unhashed(&p->rlist))
+	if (hlist_unhashed(&p->ip4_rlist))
 		return;
-	hlist_del_init_rcu(&p->rlist);
+	hlist_del_init_rcu(&p->ip4_rlist);
 	br_rtr_notify(p->br->dev, p, RTM_DELMDB);
 	br_port_mc_router_state_change(p, false);
 
@@ -3493,7 +3493,7 @@ int br_multicast_set_port_router(struct net_bridge_port
*p, unsigned long val)
 	if (p->multicast_router == val) {
 		/* Refresh the temp router port timer */
 		if (p->multicast_router == MDB_RTR_TYPE_TEMP)
-			mod_timer(&p->multicast_router_timer,
+			mod_timer(&p->ip4_mc_router_timer,
 				  now + br->multicast_querier_interval);
 		err = 0;
 		goto unlock;
@@ -3502,7 +3502,7 @@ int br_multicast_set_port_router(struct net_bridge_port
*p, unsigned long val)
 	case MDB_RTR_TYPE_DISABLED:
 		p->multicast_router = MDB_RTR_TYPE_DISABLED;
 		__del_port_router(p);
-		del_timer(&p->multicast_router_timer);
+		del_timer(&p->ip4_mc_router_timer);
 		break;
 	case MDB_RTR_TYPE_TEMP_QUERY:
 		p->multicast_router = MDB_RTR_TYPE_TEMP_QUERY;
@@ -3510,7 +3510,7 @@ int br_multicast_set_port_router(struct net_bridge_port
*p, unsigned long val)
 		break;
 	case MDB_RTR_TYPE_PERM:
 		p->multicast_router = MDB_RTR_TYPE_PERM;
-		del_timer(&p->multicast_router_timer);
+		del_timer(&p->ip4_mc_router_timer);
 		br_multicast_add_router(br, p);
 		break;
 	case MDB_RTR_TYPE_TEMP:
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index 7ce8a77..26e91d2 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -307,6 +307,8 @@ struct net_bridge_port {
 
 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
 	struct bridge_mcast_own_query	ip4_own_query;
+	struct timer_list		ip4_mc_router_timer;
+	struct hlist_node		ip4_rlist;
 #if IS_ENABLED(CONFIG_IPV6)
 	struct bridge_mcast_own_query	ip6_own_query;
 #endif /* IS_ENABLED(CONFIG_IPV6) */
@@ -314,9 +316,7 @@ struct net_bridge_port {
 	u32				multicast_eht_hosts_cnt;
 	unsigned char			multicast_router;
 	struct bridge_mcast_stats	__percpu *mcast_stats;
-	struct timer_list		multicast_router_timer;
 	struct hlist_head		mglist;
-	struct hlist_node		rlist;
 #endif
 
 #ifdef CONFIG_SYSFS
@@ -449,9 +449,9 @@ struct net_bridge {
 
 	struct hlist_head		mcast_gc_list;
 	struct hlist_head		mdb_list;
-	struct hlist_head		router_list;
 
-	struct timer_list		multicast_router_timer;
+	struct hlist_head		ip4_mc_router_list;
+	struct timer_list		ip4_mc_router_timer;
 	struct bridge_mcast_other_query	ip4_other_query;
 	struct bridge_mcast_own_query	ip4_own_query;
 	struct bridge_mcast_querier	ip4_querier;
@@ -868,7 +868,7 @@ static inline bool br_multicast_is_router(struct net_bridge
*br)
 {
 	return br->multicast_router == 2 ||
 	       (br->multicast_router == 1 &&
-		timer_pending(&br->multicast_router_timer));
+		timer_pending(&br->ip4_mc_router_timer));
 }
 
 static inline bool
-- 
2.31.0

In preparation for the upcoming split of multicast router state into
their IPv4 and IPv6 variants and to avoid IPv6 #ifdef clutter later add
two wrapper functions for router node retrieval in the payload
forwarding code.

Signed-off-by: Linus L?ssing <linus.luessing at c0d3.blue>
---
 net/bridge/br_forward.c |  5 +++--
 net/bridge/br_private.h | 10 ++++++++++
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/net/bridge/br_forward.c b/net/bridge/br_forward.c
index eb9847a..4e591b1 100644
--- a/net/bridge/br_forward.c
+++ b/net/bridge/br_forward.c
@@ -276,7 +276,8 @@ void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
 	bool allow_mode_include = true;
 	struct hlist_node *rp;
 
-	rp = rcu_dereference(hlist_first_rcu(&br->ip4_mc_router_list));
+	rp = br_multicast_get_first_rport_node(br, skb);
+
 	if (mdst) {
 		p = rcu_dereference(mdst->ports);
 		if (br_multicast_should_handle_mode(br, mdst->addr.proto) &&
@@ -290,7 +291,7 @@ void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
 		struct net_bridge_port *port, *lport, *rport;
 
 		lport = p ? p->key.port : NULL;
-		rport = hlist_entry_safe(rp, struct net_bridge_port, ip4_rlist);
+		rport = br_multicast_rport_from_node(rp, skb);
 
 		if ((unsigned long)lport > (unsigned long)rport) {
 			port = lport;
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index 26e91d2..5b9a6b2 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -864,6 +864,16 @@ static inline bool br_group_is_l2(const struct br_ip
*group)
 #define mlock_dereference(X, br) \
 	rcu_dereference_protected(X, lockdep_is_held(&br->multicast_lock))
 
+static inline struct hlist_node *
+br_multicast_get_first_rport_node(struct net_bridge *b, struct sk_buff *skb) {
+	return rcu_dereference(hlist_first_rcu(&b->ip4_mc_router_list));
+}
+
+static inline struct net_bridge_port *
+br_multicast_rport_from_node(struct hlist_node *rp, struct sk_buff *skb) {
+	return hlist_entry_safe(rp, struct net_bridge_port, ip4_rlist);
+}
+
 static inline bool br_multicast_is_router(struct net_bridge *br)
 {
 	return br->multicast_router == 2 ||
-- 
2.31.0

In preparation for the upcoming split of multicast router state into
their IPv4 and IPv6 variants and to avoid IPv6 #ifdef clutter later add
some inline functions for the protocol specific parts in the mdb router
netlink code. Also the we need iterate over the port instead of router
list to be able put one router port entry with both the IPv4 and IPv6
multicast router info later.

Signed-off-by: Linus L?ssing <linus.luessing at c0d3.blue>
---
 net/bridge/br_mdb.c | 39 ++++++++++++++++++++++++++++++++++-----
 1 file changed, 34 insertions(+), 5 deletions(-)

diff --git a/net/bridge/br_mdb.c b/net/bridge/br_mdb.c
index d61def8..482edb9 100644
--- a/net/bridge/br_mdb.c
+++ b/net/bridge/br_mdb.c
@@ -16,29 +16,58 @@
 
 #include "br_private.h"
 
+static bool br_rports_have_mc_router(struct net_bridge *br)
+{
+	return !hlist_empty(&br->ip4_mc_router_list);
+}
+
+static bool
+br_ip4_rports_get_timer(struct net_bridge_port *port, unsigned long *timer)
+{
+	*timer = br_timer_value(&port->ip4_mc_router_timer);
+	return !hlist_unhashed(&port->ip4_rlist);
+}
+
+static bool
+br_ip6_rports_get_timer(struct net_bridge_port *port, unsigned long *timer)
+{
+	*timer = 0;
+	return false;
+}
+
 static int br_rports_fill_info(struct sk_buff *skb, struct netlink_callback
*cb,
 			       struct net_device *dev)
 {
 	struct net_bridge *br = netdev_priv(dev);
-	struct net_bridge_port *p;
+	bool have_ip4_mc_rtr, have_ip6_mc_rtr;
+	unsigned long ip4_timer, ip6_timer;
 	struct nlattr *nest, *port_nest;
+	struct net_bridge_port *p;
 
-	if (!br->multicast_router || hlist_empty(&br->ip4_mc_router_list))
+	if (!br->multicast_router)
+		return 0;
+
+	if (!br_rports_have_mc_router(br))
 		return 0;
 
 	nest = nla_nest_start_noflag(skb, MDBA_ROUTER);
 	if (nest == NULL)
 		return -EMSGSIZE;
 
-	hlist_for_each_entry_rcu(p, &br->ip4_mc_router_list, ip4_rlist) {
-		if (!p)
+	list_for_each_entry_rcu(p, &br->port_list, list) {
+		have_ip4_mc_rtr = br_ip4_rports_get_timer(p, &ip4_timer);
+		have_ip6_mc_rtr = br_ip6_rports_get_timer(p, &ip6_timer);
+
+		if (!have_ip4_mc_rtr && !have_ip6_mc_rtr)
 			continue;
+
 		port_nest = nla_nest_start_noflag(skb, MDBA_ROUTER_PORT);
 		if (!port_nest)
 			goto fail;
+
 		if (nla_put_nohdr(skb, sizeof(u32), &p->dev->ifindex) ||
 		    nla_put_u32(skb, MDBA_ROUTER_PATTR_TIMER,
-				br_timer_value(&p->ip4_mc_router_timer)) ||
+				max(ip4_timer, ip6_timer)) ||
 		    nla_put_u8(skb, MDBA_ROUTER_PATTR_TYPE,
 			       p->multicast_router)) {
 			nla_nest_cancel(skb, port_nest);
-- 
2.31.0

In preparation for the upcoming split of multicast router state into
their IPv4 and IPv6 variants and as the br_multicast_mark_router() will
be split for that remove the select querier wrapper and instead add
ip4 and ip6 variants for br_multicast_query_received().

Signed-off-by: Linus L?ssing <linus.luessing at c0d3.blue>
---
 net/bridge/br_multicast.c | 53 ++++++++++++++++++++-------------------
 1 file changed, 27 insertions(+), 26 deletions(-)

diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index 6fe93a3..7edbbc9 100644
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -2615,22 +2615,6 @@ update:
 }
 #endif
 
-static bool br_multicast_select_querier(struct net_bridge *br,
-					struct net_bridge_port *port,
-					struct br_ip *saddr)
-{
-	switch (saddr->proto) {
-	case htons(ETH_P_IP):
-		return br_ip4_multicast_select_querier(br, port, saddr->src.ip4);
-#if IS_ENABLED(CONFIG_IPV6)
-	case htons(ETH_P_IPV6):
-		return br_ip6_multicast_select_querier(br, port, &saddr->src.ip6);
-#endif
-	}
-
-	return false;
-}
-
 static void
 br_multicast_update_query_timer(struct net_bridge *br,
 				struct bridge_mcast_other_query *query,
@@ -2708,19 +2692,36 @@ static void br_multicast_mark_router(struct net_bridge
*br,
 		  now + br->multicast_querier_interval);
 }
 
-static void br_multicast_query_received(struct net_bridge *br,
-					struct net_bridge_port *port,
-					struct bridge_mcast_other_query *query,
-					struct br_ip *saddr,
-					unsigned long max_delay)
+static void
+br_ip4_multicast_query_received(struct net_bridge *br,
+				struct net_bridge_port *port,
+				struct bridge_mcast_other_query *query,
+				struct br_ip *saddr,
+				unsigned long max_delay)
 {
-	if (!br_multicast_select_querier(br, port, saddr))
+	if (!br_ip4_multicast_select_querier(br, port, saddr->src.ip4))
 		return;
 
 	br_multicast_update_query_timer(br, query, max_delay);
 	br_multicast_mark_router(br, port);
 }
 
+#if IS_ENABLED(CONFIG_IPV6)
+static void
+br_ip6_multicast_query_received(struct net_bridge *br,
+				struct net_bridge_port *port,
+				struct bridge_mcast_other_query *query,
+				struct br_ip *saddr,
+				unsigned long max_delay)
+{
+	if (!br_ip6_multicast_select_querier(br, port, &saddr->src.ip6))
+		return;
+
+	br_multicast_update_query_timer(br, query, max_delay);
+	br_multicast_mark_router(br, port);
+}
+#endif
+
 static void br_ip4_multicast_query(struct net_bridge *br,
 				   struct net_bridge_port *port,
 				   struct sk_buff *skb,
@@ -2768,8 +2769,8 @@ static void br_ip4_multicast_query(struct net_bridge *br,
 		saddr.proto = htons(ETH_P_IP);
 		saddr.src.ip4 = iph->saddr;
 
-		br_multicast_query_received(br, port, &br->ip4_other_query,
-					    &saddr, max_delay);
+		br_ip4_multicast_query_received(br, port, &br->ip4_other_query,
+						&saddr, max_delay);
 		goto out;
 	}
 
@@ -2856,8 +2857,8 @@ static int br_ip6_multicast_query(struct net_bridge *br,
 		saddr.proto = htons(ETH_P_IPV6);
 		saddr.src.ip6 = ipv6_hdr(skb)->saddr;
 
-		br_multicast_query_received(br, port, &br->ip6_other_query,
-					    &saddr, max_delay);
+		br_ip6_multicast_query_received(br, port, &br->ip6_other_query,
+						&saddr, max_delay);
 		goto out;
 	} else if (!group) {
 		goto out;
-- 
2.31.0

In preparation for the upcoming split of multicast router state into
their IPv4 and IPv6 variants make br_multicast_is_router() protocol
family aware.

Note that for now br_ip6_multicast_is_router() uses the currently still
common ip4_mc_router_timer for now. It will be renamed to
ip6_mc_router_timer later when the split is performed.

While at it also renames the "1" and "2" constants in
br_multicast_is_router() to the MDB_RTR_TYPE_TEMP_QUERY and
MDB_RTR_TYPE_PERM enums.

Signed-off-by: Linus L?ssing <linus.luessing at c0d3.blue>
---
 net/bridge/br_input.c     |  2 +-
 net/bridge/br_multicast.c |  5 +++--
 net/bridge/br_private.h   | 37 +++++++++++++++++++++++++++++++++----
 3 files changed, 37 insertions(+), 7 deletions(-)

diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
index 8875e95..1f50630 100644
--- a/net/bridge/br_input.c
+++ b/net/bridge/br_input.c
@@ -132,7 +132,7 @@ int br_handle_frame_finish(struct net *net, struct sock *sk,
struct sk_buff *skb
 		if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
 		    br_multicast_querier_exists(br, eth_hdr(skb), mdst)) {
 			if ((mdst && mdst->host_joined) ||
-			    br_multicast_is_router(br)) {
+			    br_multicast_is_router(br, skb)) {
 				local_rcv = true;
 				br->dev->stats.multicast++;
 			}
diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index 7edbbc9..048b5b9 100644
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -1391,7 +1391,8 @@ static void br_multicast_local_router_expired(struct
timer_list *t)
 	spin_lock(&br->multicast_lock);
 	if (br->multicast_router == MDB_RTR_TYPE_DISABLED ||
 	    br->multicast_router == MDB_RTR_TYPE_PERM ||
-	    timer_pending(&br->ip4_mc_router_timer))
+	    br_ip4_multicast_is_router(br) ||
+	    br_ip6_multicast_is_router(br))
 		goto out;
 
 	br_mc_router_state_change(br, false);
@@ -3622,7 +3623,7 @@ bool br_multicast_router(const struct net_device *dev)
 	bool is_router;
 
 	spin_lock_bh(&br->multicast_lock);
-	is_router = br_multicast_is_router(br);
+	is_router = br_multicast_is_router(br, NULL);
 	spin_unlock_bh(&br->multicast_lock);
 	return is_router;
 }
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index 5b9a6b2..41ed3fe 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -874,11 +874,40 @@ br_multicast_rport_from_node(struct hlist_node *rp, struct
sk_buff *skb) {
 	return hlist_entry_safe(rp, struct net_bridge_port, ip4_rlist);
 }
 
-static inline bool br_multicast_is_router(struct net_bridge *br)
+static inline bool br_ip4_multicast_is_router(struct net_bridge *br)
 {
-	return br->multicast_router == 2 ||
-	       (br->multicast_router == 1 &&
-		timer_pending(&br->ip4_mc_router_timer));
+	return timer_pending(&br->ip4_mc_router_timer);
+}
+
+static inline bool br_ip6_multicast_is_router(struct net_bridge *br)
+{
+#if IS_ENABLED(CONFIG_IPV6)
+	return timer_pending(&br->ip4_mc_router_timer);
+#else
+	return false;
+#endif
+}
+
+static inline bool
+br_multicast_is_router(struct net_bridge *br, struct sk_buff *skb)
+{
+	switch (br->multicast_router) {
+	case MDB_RTR_TYPE_PERM:
+		return true;
+	case MDB_RTR_TYPE_TEMP_QUERY:
+		if (skb) {
+			if (skb->protocol == htons(ETH_P_IP))
+				return br_ip4_multicast_is_router(br);
+			else if (skb->protocol == htons(ETH_P_IPV6))
+				return br_ip6_multicast_is_router(br);
+		} else {
+			return br_ip4_multicast_is_router(br) ||
+			       br_ip6_multicast_is_router(br);
+		}
+		fallthrough;
+	default:
+		return false;
+	}
 }
 
 static inline bool
-- 
2.31.0

In preparation for the upcoming split of multicast router state into
their IPv4 and IPv6 variants move the protocol specific timer access to
an ip4 wrapper function.

Signed-off-by: Linus L?ssing <linus.luessing at c0d3.blue>
---
 net/bridge/br_multicast.c | 31 ++++++++++++++++++++++---------
 1 file changed, 22 insertions(+), 9 deletions(-)

diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index 048b5b9..7815991 100644
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -1354,16 +1354,16 @@ static int br_ip6_multicast_add_group(struct net_bridge
*br,
 }
 #endif
 
-static void br_multicast_router_expired(struct timer_list *t)
+static void br_multicast_router_expired(struct net_bridge_port *port,
+					struct timer_list *t,
+					struct hlist_node *rlist)
 {
-	struct net_bridge_port *port -			from_timer(port, t, ip4_mc_router_timer);
 	struct net_bridge *br = port->br;
 
 	spin_lock(&br->multicast_lock);
 	if (port->multicast_router == MDB_RTR_TYPE_DISABLED ||
 	    port->multicast_router == MDB_RTR_TYPE_PERM ||
-	    timer_pending(&port->ip4_mc_router_timer))
+	    timer_pending(t))
 		goto out;
 
 	__del_port_router(port);
@@ -1371,6 +1371,13 @@ out:
 	spin_unlock(&br->multicast_lock);
 }
 
+static void br_ip4_multicast_router_expired(struct timer_list *t)
+{
+	struct net_bridge_port *port = from_timer(port, t, ip4_mc_router_timer);
+
+	br_multicast_router_expired(port, t, &port->ip4_rlist);
+}
+
 static void br_mc_router_state_change(struct net_bridge *p,
 				      bool is_mc_router)
 {
@@ -1384,10 +1391,9 @@ static void br_mc_router_state_change(struct net_bridge
*p,
 	switchdev_port_attr_set(p->dev, &attr, NULL);
 }
 
-static void br_multicast_local_router_expired(struct timer_list *t)
+static void br_multicast_local_router_expired(struct net_bridge *br,
+					      struct timer_list *timer)
 {
-	struct net_bridge *br = from_timer(br, t, ip4_mc_router_timer);
-
 	spin_lock(&br->multicast_lock);
 	if (br->multicast_router == MDB_RTR_TYPE_DISABLED ||
 	    br->multicast_router == MDB_RTR_TYPE_PERM ||
@@ -1400,6 +1406,13 @@ out:
 	spin_unlock(&br->multicast_lock);
 }
 
+static void br_ip4_multicast_local_router_expired(struct timer_list *t)
+{
+	struct net_bridge *br = from_timer(br, t, ip4_mc_router_timer);
+
+	br_multicast_local_router_expired(br, t);
+}
+
 static void br_multicast_querier_expired(struct net_bridge *br,
 					 struct bridge_mcast_own_query *query)
 {
@@ -1615,7 +1628,7 @@ int br_multicast_add_port(struct net_bridge_port *port)
 	port->multicast_eht_hosts_limit = BR_MCAST_DEFAULT_EHT_HOSTS_LIMIT;
 
 	timer_setup(&port->ip4_mc_router_timer,
-		    br_multicast_router_expired, 0);
+		    br_ip4_multicast_router_expired, 0);
 	timer_setup(&port->ip4_own_query.timer,
 		    br_ip4_multicast_port_query_expired, 0);
 #if IS_ENABLED(CONFIG_IPV6)
@@ -3319,7 +3332,7 @@ void br_multicast_init(struct net_bridge *br)
 
 	spin_lock_init(&br->multicast_lock);
 	timer_setup(&br->ip4_mc_router_timer,
-		    br_multicast_local_router_expired, 0);
+		    br_ip4_multicast_local_router_expired, 0);
 	timer_setup(&br->ip4_other_query.timer,
 		    br_ip4_multicast_querier_expired, 0);
 	timer_setup(&br->ip4_own_query.timer,
-- 
2.31.0

In preparation for the upcoming split of multicast router state into
their IPv4 and IPv6 variants move the protocol specific router list
access to an ip4 wrapper function.

Signed-off-by: Linus L?ssing <linus.luessing at c0d3.blue>
---
 net/bridge/br_multicast.c | 59 +++++++++++++++++++++++++++------------
 1 file changed, 41 insertions(+), 18 deletions(-)

diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index 7815991..1d55709 100644
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -51,8 +51,8 @@ static const struct rhashtable_params br_sg_port_rht_params =
{
 
 static void br_multicast_start_querier(struct net_bridge *br,
 				       struct bridge_mcast_own_query *query);
-static void br_multicast_add_router(struct net_bridge *br,
-				    struct net_bridge_port *port);
+static void br_ip4_multicast_add_router(struct net_bridge *br,
+					struct net_bridge_port *port);
 static void br_ip4_multicast_leave_group(struct net_bridge *br,
 					 struct net_bridge_port *port,
 					 __be32 group,
@@ -1689,7 +1689,7 @@ static void __br_multicast_enable_port(struct
net_bridge_port *port)
 #endif
 	if (port->multicast_router == MDB_RTR_TYPE_PERM &&
 	    hlist_unhashed(&port->ip4_rlist))
-		br_multicast_add_router(br, port);
+		br_ip4_multicast_add_router(br, port);
 }
 
 void br_multicast_enable_port(struct net_bridge_port *port)
@@ -2659,28 +2659,51 @@ static void br_port_mc_router_state_change(struct
net_bridge_port *p,
  *  and locked by br->multicast_lock and RCU
  */
 static void br_multicast_add_router(struct net_bridge *br,
-				    struct net_bridge_port *port)
+				    struct net_bridge_port *port,
+				    struct hlist_node *slot,
+				    struct hlist_node *rlist,
+				    struct hlist_head *mc_router_list)
 {
-	struct net_bridge_port *p;
-	struct hlist_node *slot = NULL;
-
-	if (!hlist_unhashed(&port->ip4_rlist))
+	if (!hlist_unhashed(rlist))
 		return;
 
-	hlist_for_each_entry(p, &br->ip4_mc_router_list, ip4_rlist) {
-		if ((unsigned long) port >= (unsigned long) p)
-			break;
-		slot = &p->ip4_rlist;
-	}
-
 	if (slot)
-		hlist_add_behind_rcu(&port->ip4_rlist, slot);
+		hlist_add_behind_rcu(rlist, slot);
 	else
-		hlist_add_head_rcu(&port->ip4_rlist, &br->ip4_mc_router_list);
+		hlist_add_head_rcu(rlist, mc_router_list);
+
 	br_rtr_notify(br->dev, port, RTM_NEWMDB);
 	br_port_mc_router_state_change(port, true);
 }
 
+static struct hlist_node *
+br_ip4_multicast_get_rport_slot(struct net_bridge *br, struct net_bridge_port
*port)
+{
+	struct hlist_node *slot = NULL;
+	struct net_bridge_port *p;
+
+	hlist_for_each_entry(p, &br->ip4_mc_router_list, ip4_rlist) {
+		if ((unsigned long)port >= (unsigned long)p)
+			break;
+		slot = &p->ip4_rlist;
+	}
+
+	return slot;
+}
+
+/* Add port to router_list
+ *  list is maintained ordered by pointer value
+ *  and locked by br->multicast_lock and RCU
+ */
+static void br_ip4_multicast_add_router(struct net_bridge *br,
+					struct net_bridge_port *port)
+{
+	struct hlist_node *slot = br_ip4_multicast_get_rport_slot(br, port);
+
+	br_multicast_add_router(br, port, slot, &port->ip4_rlist,
+				&br->ip4_mc_router_list);
+}
+
 static void br_multicast_mark_router(struct net_bridge *br,
 				     struct net_bridge_port *port)
 {
@@ -2700,7 +2723,7 @@ static void br_multicast_mark_router(struct net_bridge
*br,
 	    port->multicast_router == MDB_RTR_TYPE_PERM)
 		return;
 
-	br_multicast_add_router(br, port);
+	br_ip4_multicast_add_router(br, port);
 
 	mod_timer(&port->ip4_mc_router_timer,
 		  now + br->multicast_querier_interval);
@@ -3526,7 +3549,7 @@ int br_multicast_set_port_router(struct net_bridge_port
*p, unsigned long val)
 	case MDB_RTR_TYPE_PERM:
 		p->multicast_router = MDB_RTR_TYPE_PERM;
 		del_timer(&p->ip4_mc_router_timer);
-		br_multicast_add_router(br, p);
+		br_ip4_multicast_add_router(br, p);
 		break;
 	case MDB_RTR_TYPE_TEMP:
 		p->multicast_router = MDB_RTR_TYPE_TEMP;
-- 
2.31.0

In preparation for the upcoming split of multicast router state into
their IPv4 and IPv6 variants split router port deletion and notification
into two functions. When we disable a port for instance later we want to
only send one notification to switchdev and netlink for compatibility
and want to avoid sending one for IPv4 and one for IPv6. For that the
split is needed.

Signed-off-by: Linus L?ssing <linus.luessing at c0d3.blue>
---
 net/bridge/br_multicast.c | 40 ++++++++++++++++++++++++++++++---------
 1 file changed, 31 insertions(+), 9 deletions(-)

diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index 1d55709..01a1de4 100644
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -60,7 +60,8 @@ static void br_ip4_multicast_leave_group(struct net_bridge
*br,
 					 const unsigned char *src);
 static void br_multicast_port_group_rexmit(struct timer_list *t);
 
-static void __del_port_router(struct net_bridge_port *p);
+static void
+br_multicast_rport_del_notify(struct net_bridge_port *p, bool deleted);
 #if IS_ENABLED(CONFIG_IPV6)
 static void br_ip6_multicast_leave_group(struct net_bridge *br,
 					 struct net_bridge_port *port,
@@ -1354,11 +1355,26 @@ static int br_ip6_multicast_add_group(struct net_bridge
*br,
 }
 #endif
 
+static bool br_multicast_rport_del(struct hlist_node *rlist)
+{
+	if (hlist_unhashed(rlist))
+		return false;
+
+	hlist_del_init_rcu(rlist);
+	return true;
+}
+
+static bool br_ip4_multicast_rport_del(struct net_bridge_port *p)
+{
+	return br_multicast_rport_del(&p->ip4_rlist);
+}
+
 static void br_multicast_router_expired(struct net_bridge_port *port,
 					struct timer_list *t,
 					struct hlist_node *rlist)
 {
 	struct net_bridge *br = port->br;
+	bool del;
 
 	spin_lock(&br->multicast_lock);
 	if (port->multicast_router == MDB_RTR_TYPE_DISABLED ||
@@ -1366,7 +1382,8 @@ static void br_multicast_router_expired(struct
net_bridge_port *port,
 	    timer_pending(t))
 		goto out;
 
-	__del_port_router(port);
+	del = br_multicast_rport_del(rlist);
+	br_multicast_rport_del_notify(port, del);
 out:
 	spin_unlock(&br->multicast_lock);
 }
@@ -1706,19 +1723,20 @@ void br_multicast_disable_port(struct net_bridge_port
*port)
 	struct net_bridge *br = port->br;
 	struct net_bridge_port_group *pg;
 	struct hlist_node *n;
+	bool del = false;
 
 	spin_lock(&br->multicast_lock);
 	hlist_for_each_entry_safe(pg, n, &port->mglist, mglist)
 		if (!(pg->flags & MDB_PG_FLAGS_PERMANENT))
 			br_multicast_find_del_pg(br, pg);
 
-	__del_port_router(port);
-
+	del |= br_ip4_multicast_rport_del(port);
 	del_timer(&port->ip4_mc_router_timer);
 	del_timer(&port->ip4_own_query.timer);
 #if IS_ENABLED(CONFIG_IPV6)
 	del_timer(&port->ip6_own_query.timer);
 #endif
+	br_multicast_rport_del_notify(port, del);
 	spin_unlock(&br->multicast_lock);
 }
 
@@ -3508,11 +3526,12 @@ int br_multicast_set_router(struct net_bridge *br,
unsigned long val)
 	return err;
 }
 
-static void __del_port_router(struct net_bridge_port *p)
+static void
+br_multicast_rport_del_notify(struct net_bridge_port *p, bool deleted)
 {
-	if (hlist_unhashed(&p->ip4_rlist))
+	if (!deleted)
 		return;
-	hlist_del_init_rcu(&p->ip4_rlist);
+
 	br_rtr_notify(p->br->dev, p, RTM_DELMDB);
 	br_port_mc_router_state_change(p, false);
 
@@ -3526,6 +3545,7 @@ int br_multicast_set_port_router(struct net_bridge_port
*p, unsigned long val)
 	struct net_bridge *br = p->br;
 	unsigned long now = jiffies;
 	int err = -EINVAL;
+	bool del = false;
 
 	spin_lock(&br->multicast_lock);
 	if (p->multicast_router == val) {
@@ -3539,12 +3559,14 @@ int br_multicast_set_port_router(struct net_bridge_port
*p, unsigned long val)
 	switch (val) {
 	case MDB_RTR_TYPE_DISABLED:
 		p->multicast_router = MDB_RTR_TYPE_DISABLED;
-		__del_port_router(p);
+		del |= br_ip4_multicast_rport_del(p);
 		del_timer(&p->ip4_mc_router_timer);
+		br_multicast_rport_del_notify(p, del);
 		break;
 	case MDB_RTR_TYPE_TEMP_QUERY:
 		p->multicast_router = MDB_RTR_TYPE_TEMP_QUERY;
-		__del_port_router(p);
+		del |= br_ip4_multicast_rport_del(p);
+		br_multicast_rport_del_notify(p, del);
 		break;
 	case MDB_RTR_TYPE_PERM:
 		p->multicast_router = MDB_RTR_TYPE_PERM;
-- 
2.31.0

A multicast router for IPv4 does not imply that the same host also is a
multicast router for IPv6 and vice versa.

To reduce multicast traffic when a host is only a multicast router for
one of these two protocol families, keep router state for IPv4 and IPv6
separately. Similar to how querier state is kept separately.

For backwards compatibility for netlink and switchdev notifications
these two will still only notify if a port switched from either no
IPv4/IPv6 multicast router to any IPv4/IPv6 multicast router or the
other way round. However a full netlink MDB router dump will now also
include a multicast router timeout for both IPv4 and IPv6.

Signed-off-by: Linus L?ssing <linus.luessing at c0d3.blue>
---
 net/bridge/br_mdb.c       |  10 ++
 net/bridge/br_multicast.c | 197 ++++++++++++++++++++++++++++++++++----
 net/bridge/br_private.h   |  14 ++-
 3 files changed, 201 insertions(+), 20 deletions(-)

diff --git a/net/bridge/br_mdb.c b/net/bridge/br_mdb.c
index 482edb9..10c416c 100644
--- a/net/bridge/br_mdb.c
+++ b/net/bridge/br_mdb.c
@@ -18,7 +18,12 @@
 
 static bool br_rports_have_mc_router(struct net_bridge *br)
 {
+#if IS_ENABLED(CONFIG_IPV6)
+	return !hlist_empty(&br->ip4_mc_router_list) ||
+	       !hlist_empty(&br->ip6_mc_router_list);
+#else
 	return !hlist_empty(&br->ip4_mc_router_list);
+#endif
 }
 
 static bool
@@ -31,8 +36,13 @@ br_ip4_rports_get_timer(struct net_bridge_port *port,
unsigned long *timer)
 static bool
 br_ip6_rports_get_timer(struct net_bridge_port *port, unsigned long *timer)
 {
+#if IS_ENABLED(CONFIG_IPV6)
+	*timer = br_timer_value(&port->ip6_mc_router_timer);
+	return !hlist_unhashed(&port->ip6_rlist);
+#else
 	*timer = 0;
 	return false;
+#endif
 }
 
 static int br_rports_fill_info(struct sk_buff *skb, struct netlink_callback
*cb,
diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index 01a1de4..4448490 100644
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -63,6 +63,8 @@ static void br_multicast_port_group_rexmit(struct timer_list
*t);
 static void
 br_multicast_rport_del_notify(struct net_bridge_port *p, bool deleted);
 #if IS_ENABLED(CONFIG_IPV6)
+static void br_ip6_multicast_add_router(struct net_bridge *br,
+					struct net_bridge_port *port);
 static void br_ip6_multicast_leave_group(struct net_bridge *br,
 					 struct net_bridge_port *port,
 					 const struct in6_addr *group,
@@ -1369,6 +1371,15 @@ static bool br_ip4_multicast_rport_del(struct
net_bridge_port *p)
 	return br_multicast_rport_del(&p->ip4_rlist);
 }
 
+static bool br_ip6_multicast_rport_del(struct net_bridge_port *p)
+{
+#if IS_ENABLED(CONFIG_IPV6)
+	return br_multicast_rport_del(&p->ip6_rlist);
+#else
+	return false;
+#endif
+}
+
 static void br_multicast_router_expired(struct net_bridge_port *port,
 					struct timer_list *t,
 					struct hlist_node *rlist)
@@ -1395,6 +1406,15 @@ static void br_ip4_multicast_router_expired(struct
timer_list *t)
 	br_multicast_router_expired(port, t, &port->ip4_rlist);
 }
 
+#if IS_ENABLED(CONFIG_IPV6)
+static void br_ip6_multicast_router_expired(struct timer_list *t)
+{
+	struct net_bridge_port *port = from_timer(port, t, ip6_mc_router_timer);
+
+	br_multicast_router_expired(port, t, &port->ip6_rlist);
+}
+#endif
+
 static void br_mc_router_state_change(struct net_bridge *p,
 				      bool is_mc_router)
 {
@@ -1430,6 +1450,15 @@ static void br_ip4_multicast_local_router_expired(struct
timer_list *t)
 	br_multicast_local_router_expired(br, t);
 }
 
+#if IS_ENABLED(CONFIG_IPV6)
+static void br_ip6_multicast_local_router_expired(struct timer_list *t)
+{
+	struct net_bridge *br = from_timer(br, t, ip6_mc_router_timer);
+
+	br_multicast_local_router_expired(br, t);
+}
+#endif
+
 static void br_multicast_querier_expired(struct net_bridge *br,
 					 struct bridge_mcast_own_query *query)
 {
@@ -1649,6 +1678,8 @@ int br_multicast_add_port(struct net_bridge_port *port)
 	timer_setup(&port->ip4_own_query.timer,
 		    br_ip4_multicast_port_query_expired, 0);
 #if IS_ENABLED(CONFIG_IPV6)
+	timer_setup(&port->ip6_mc_router_timer,
+		    br_ip6_multicast_router_expired, 0);
 	timer_setup(&port->ip6_own_query.timer,
 		    br_ip6_multicast_port_query_expired, 0);
 #endif
@@ -1681,6 +1712,9 @@ void br_multicast_del_port(struct net_bridge_port *port)
 	spin_unlock_bh(&br->multicast_lock);
 	br_multicast_gc(&deleted_head);
 	del_timer_sync(&port->ip4_mc_router_timer);
+#if IS_ENABLED(CONFIG_IPV6)
+	del_timer_sync(&port->ip6_mc_router_timer);
+#endif
 	free_percpu(port->mcast_stats);
 }
 
@@ -1704,9 +1738,14 @@ static void __br_multicast_enable_port(struct
net_bridge_port *port)
 #if IS_ENABLED(CONFIG_IPV6)
 	br_multicast_enable(&port->ip6_own_query);
 #endif
-	if (port->multicast_router == MDB_RTR_TYPE_PERM &&
-	    hlist_unhashed(&port->ip4_rlist))
-		br_ip4_multicast_add_router(br, port);
+	if (port->multicast_router == MDB_RTR_TYPE_PERM) {
+		if (hlist_unhashed(&port->ip4_rlist))
+			br_ip4_multicast_add_router(br, port);
+#if IS_ENABLED(CONFIG_IPV6)
+		if (hlist_unhashed(&port->ip6_rlist))
+			br_ip6_multicast_add_router(br, port);
+#endif
+	}
 }
 
 void br_multicast_enable_port(struct net_bridge_port *port)
@@ -1733,7 +1772,9 @@ void br_multicast_disable_port(struct net_bridge_port
*port)
 	del |= br_ip4_multicast_rport_del(port);
 	del_timer(&port->ip4_mc_router_timer);
 	del_timer(&port->ip4_own_query.timer);
+	del |= br_ip6_multicast_rport_del(port);
 #if IS_ENABLED(CONFIG_IPV6)
+	del_timer(&port->ip6_mc_router_timer);
 	del_timer(&port->ip6_own_query.timer);
 #endif
 	br_multicast_rport_del_notify(port, del);
@@ -2671,11 +2712,19 @@ static void br_port_mc_router_state_change(struct
net_bridge_port *p,
 	switchdev_port_attr_set(p->dev, &attr, NULL);
 }
 
-/*
- * Add port to router_list
- *  list is maintained ordered by pointer value
- *  and locked by br->multicast_lock and RCU
- */
+static bool br_multicast_no_router_otherpf(struct net_bridge_port *port,
+					   struct hlist_node *rnode)
+{
+#if IS_ENABLED(CONFIG_IPV6)
+	if (rnode != &port->ip6_rlist)
+		return hlist_unhashed(&port->ip6_rlist);
+	else
+		return hlist_unhashed(&port->ip4_rlist);
+#else
+	return true;
+#endif
+}
+
 static void br_multicast_add_router(struct net_bridge *br,
 				    struct net_bridge_port *port,
 				    struct hlist_node *slot,
@@ -2690,8 +2739,14 @@ static void br_multicast_add_router(struct net_bridge
*br,
 	else
 		hlist_add_head_rcu(rlist, mc_router_list);
 
-	br_rtr_notify(br->dev, port, RTM_NEWMDB);
-	br_port_mc_router_state_change(port, true);
+	/* For backwards compatibility for now, only notify if we
+	 * switched from no IPv4/IPv6 multicast router to a new
+	 * IPv4 or IPv6 multicast router.
+	 */
+	if (br_multicast_no_router_otherpf(port, rlist)) {
+		br_rtr_notify(br->dev, port, RTM_NEWMDB);
+		br_port_mc_router_state_change(port, true);
+	}
 }
 
 static struct hlist_node *
@@ -2722,14 +2777,54 @@ static void br_ip4_multicast_add_router(struct
net_bridge *br,
 				&br->ip4_mc_router_list);
 }
 
-static void br_multicast_mark_router(struct net_bridge *br,
-				     struct net_bridge_port *port)
+#if IS_ENABLED(CONFIG_IPV6)
+static struct hlist_node *
+br_ip6_multicast_get_rport_slot(struct net_bridge *br, struct net_bridge_port
*port)
+{
+	struct hlist_node *slot = NULL;
+	struct net_bridge_port *p;
+
+	hlist_for_each_entry(p, &br->ip6_mc_router_list, ip6_rlist) {
+		if ((unsigned long)port >= (unsigned long)p)
+			break;
+		slot = &p->ip6_rlist;
+	}
+
+	return slot;
+}
+
+/* Add port to router_list
+ *  list is maintained ordered by pointer value
+ *  and locked by br->multicast_lock and RCU
+ */
+static void br_ip6_multicast_add_router(struct net_bridge *br,
+					struct net_bridge_port *port)
+{
+	struct hlist_node *slot = br_ip6_multicast_get_rport_slot(br, port);
+
+	br_multicast_add_router(br, port, slot, &port->ip6_rlist,
+				&br->ip6_mc_router_list);
+}
+#else
+static inline void br_ip6_multicast_add_router(struct net_bridge *br,
+					       struct net_bridge_port *port)
+{
+}
+#endif
+
+static void br_ip4_multicast_mark_router(struct net_bridge *br,
+					 struct net_bridge_port *port)
 {
 	unsigned long now = jiffies;
 
 	if (!port) {
 		if (br->multicast_router == MDB_RTR_TYPE_TEMP_QUERY) {
+#if IS_ENABLED(CONFIG_IPV6)
+			if (!timer_pending(&br->ip4_mc_router_timer) &&
+			    !timer_pending(&br->ip6_mc_router_timer))
+#else
 			if (!timer_pending(&br->ip4_mc_router_timer))
+#endif
 				br_mc_router_state_change(br, true);
 			mod_timer(&br->ip4_mc_router_timer,
 				  now + br->multicast_querier_interval);
@@ -2747,6 +2842,39 @@ static void br_multicast_mark_router(struct net_bridge
*br,
 		  now + br->multicast_querier_interval);
 }
 
+#if IS_ENABLED(CONFIG_IPV6)
+static void br_ip6_multicast_mark_router(struct net_bridge *br,
+					 struct net_bridge_port *port)
+{
+	unsigned long now = jiffies;
+
+	if (!port) {
+		if (br->multicast_router == MDB_RTR_TYPE_TEMP_QUERY) {
+			if (!timer_pending(&br->ip4_mc_router_timer) &&
+			    !timer_pending(&br->ip6_mc_router_timer))
+				br_mc_router_state_change(br, true);
+			mod_timer(&br->ip6_mc_router_timer,
+				  now + br->multicast_querier_interval);
+		}
+		return;
+	}
+
+	if (port->multicast_router == MDB_RTR_TYPE_DISABLED ||
+	    port->multicast_router == MDB_RTR_TYPE_PERM)
+		return;
+
+	br_ip6_multicast_add_router(br, port);
+
+	mod_timer(&port->ip6_mc_router_timer,
+		  now + br->multicast_querier_interval);
+}
+#else
+static inline void br_ip6_multicast_mark_router(struct net_bridge *br,
+						struct net_bridge_port *port)
+{
+}
+#endif
+
 static void
 br_ip4_multicast_query_received(struct net_bridge *br,
 				struct net_bridge_port *port,
@@ -2758,7 +2886,7 @@ br_ip4_multicast_query_received(struct net_bridge *br,
 		return;
 
 	br_multicast_update_query_timer(br, query, max_delay);
-	br_multicast_mark_router(br, port);
+	br_ip4_multicast_mark_router(br, port);
 }
 
 #if IS_ENABLED(CONFIG_IPV6)
@@ -2773,7 +2901,7 @@ br_ip6_multicast_query_received(struct net_bridge *br,
 		return;
 
 	br_multicast_update_query_timer(br, query, max_delay);
-	br_multicast_mark_router(br, port);
+	br_ip6_multicast_mark_router(br, port);
 }
 #endif
 
@@ -3143,7 +3271,7 @@ static void br_multicast_pim(struct net_bridge *br,
 	    pim_hdr_type(pimhdr) != PIM_TYPE_HELLO)
 		return;
 
-	br_multicast_mark_router(br, port);
+	br_ip4_multicast_mark_router(br, port);
 }
 
 static int br_ip4_multicast_mrd_rcv(struct net_bridge *br,
@@ -3154,7 +3282,7 @@ static int br_ip4_multicast_mrd_rcv(struct net_bridge *br,
 	    igmp_hdr(skb)->type != IGMP_MRDISC_ADV)
 		return -ENOMSG;
 
-	br_multicast_mark_router(br, port);
+	br_ip4_multicast_mark_router(br, port);
 
 	return 0;
 }
@@ -3222,7 +3350,7 @@ static void br_ip6_multicast_mrd_rcv(struct net_bridge
*br,
 	if (icmp6_hdr(skb)->icmp6_type != ICMPV6_MRDISC_ADV)
 		return;
 
-	br_multicast_mark_router(br, port);
+	br_ip6_multicast_mark_router(br, port);
 }
 
 static int br_multicast_ipv6_rcv(struct net_bridge *br,
@@ -3379,6 +3507,8 @@ void br_multicast_init(struct net_bridge *br)
 	timer_setup(&br->ip4_own_query.timer,
 		    br_ip4_multicast_query_expired, 0);
 #if IS_ENABLED(CONFIG_IPV6)
+	timer_setup(&br->ip6_mc_router_timer,
+		    br_ip6_multicast_local_router_expired, 0);
 	timer_setup(&br->ip6_other_query.timer,
 		    br_ip6_multicast_querier_expired, 0);
 	timer_setup(&br->ip6_own_query.timer,
@@ -3476,6 +3606,7 @@ void br_multicast_stop(struct net_bridge *br)
 	del_timer_sync(&br->ip4_other_query.timer);
 	del_timer_sync(&br->ip4_own_query.timer);
 #if IS_ENABLED(CONFIG_IPV6)
+	del_timer_sync(&br->ip6_mc_router_timer);
 	del_timer_sync(&br->ip6_other_query.timer);
 	del_timer_sync(&br->ip6_own_query.timer);
 #endif
@@ -3510,6 +3641,9 @@ int br_multicast_set_router(struct net_bridge *br,
unsigned long val)
 	case MDB_RTR_TYPE_PERM:
 		br_mc_router_state_change(br, val == MDB_RTR_TYPE_PERM);
 		del_timer(&br->ip4_mc_router_timer);
+#if IS_ENABLED(CONFIG_IPV6)
+		del_timer(&br->ip6_mc_router_timer);
+#endif
 		br->multicast_router = val;
 		err = 0;
 		break;
@@ -3532,6 +3666,16 @@ br_multicast_rport_del_notify(struct net_bridge_port *p,
bool deleted)
 	if (!deleted)
 		return;
 
+	/* For backwards compatibility for now, only notify if there is
+	 * no multicast router anymore for both IPv4 and IPv6.
+	 */
+	if (!hlist_unhashed(&p->ip4_rlist))
+		return;
+#if IS_ENABLED(CONFIG_IPV6)
+	if (!hlist_unhashed(&p->ip6_rlist))
+		return;
+#endif
+
 	br_rtr_notify(p->br->dev, p, RTM_DELMDB);
 	br_port_mc_router_state_change(p, false);
 
@@ -3550,9 +3694,14 @@ int br_multicast_set_port_router(struct net_bridge_port
*p, unsigned long val)
 	spin_lock(&br->multicast_lock);
 	if (p->multicast_router == val) {
 		/* Refresh the temp router port timer */
-		if (p->multicast_router == MDB_RTR_TYPE_TEMP)
+		if (p->multicast_router == MDB_RTR_TYPE_TEMP) {
 			mod_timer(&p->ip4_mc_router_timer,
 				  now + br->multicast_querier_interval);
+#if IS_ENABLED(CONFIG_IPV6)
+			mod_timer(&p->ip6_mc_router_timer,
+				  now + br->multicast_querier_interval);
+#endif
+		}
 		err = 0;
 		goto unlock;
 	}
@@ -3561,21 +3710,31 @@ int br_multicast_set_port_router(struct net_bridge_port
*p, unsigned long val)
 		p->multicast_router = MDB_RTR_TYPE_DISABLED;
 		del |= br_ip4_multicast_rport_del(p);
 		del_timer(&p->ip4_mc_router_timer);
+		del |= br_ip6_multicast_rport_del(p);
+#if IS_ENABLED(CONFIG_IPV6)
+		del_timer(&p->ip6_mc_router_timer);
+#endif
 		br_multicast_rport_del_notify(p, del);
 		break;
 	case MDB_RTR_TYPE_TEMP_QUERY:
 		p->multicast_router = MDB_RTR_TYPE_TEMP_QUERY;
 		del |= br_ip4_multicast_rport_del(p);
+		del |= br_ip6_multicast_rport_del(p);
 		br_multicast_rport_del_notify(p, del);
 		break;
 	case MDB_RTR_TYPE_PERM:
 		p->multicast_router = MDB_RTR_TYPE_PERM;
 		del_timer(&p->ip4_mc_router_timer);
 		br_ip4_multicast_add_router(br, p);
+#if IS_ENABLED(CONFIG_IPV6)
+		del_timer(&p->ip6_mc_router_timer);
+#endif
+		br_ip6_multicast_add_router(br, p);
 		break;
 	case MDB_RTR_TYPE_TEMP:
 		p->multicast_router = MDB_RTR_TYPE_TEMP;
-		br_multicast_mark_router(br, p);
+		br_ip4_multicast_mark_router(br, p);
+		br_ip6_multicast_mark_router(br, p);
 		break;
 	default:
 		goto unlock;
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index 41ed3fe..a2e7b9e 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -311,6 +311,8 @@ struct net_bridge_port {
 	struct hlist_node		ip4_rlist;
 #if IS_ENABLED(CONFIG_IPV6)
 	struct bridge_mcast_own_query	ip6_own_query;
+	struct timer_list		ip6_mc_router_timer;
+	struct hlist_node		ip6_rlist;
 #endif /* IS_ENABLED(CONFIG_IPV6) */
 	u32				multicast_eht_hosts_limit;
 	u32				multicast_eht_hosts_cnt;
@@ -457,6 +459,8 @@ struct net_bridge {
 	struct bridge_mcast_querier	ip4_querier;
 	struct bridge_mcast_stats	__percpu *mcast_stats;
 #if IS_ENABLED(CONFIG_IPV6)
+	struct hlist_head		ip6_mc_router_list;
+	struct timer_list		ip6_mc_router_timer;
 	struct bridge_mcast_other_query	ip6_other_query;
 	struct bridge_mcast_own_query	ip6_own_query;
 	struct bridge_mcast_querier	ip6_querier;
@@ -866,11 +870,19 @@ static inline bool br_group_is_l2(const struct br_ip
*group)
 
 static inline struct hlist_node *
 br_multicast_get_first_rport_node(struct net_bridge *b, struct sk_buff *skb) {
+#if IS_ENABLED(CONFIG_IPV6)
+	if (skb->protocol == htons(ETH_P_IPV6))
+		return rcu_dereference(hlist_first_rcu(&b->ip6_mc_router_list));
+#endif
 	return rcu_dereference(hlist_first_rcu(&b->ip4_mc_router_list));
 }
 
 static inline struct net_bridge_port *
 br_multicast_rport_from_node(struct hlist_node *rp, struct sk_buff *skb) {
+#if IS_ENABLED(CONFIG_IPV6)
+	if (skb->protocol == htons(ETH_P_IPV6))
+		return hlist_entry_safe(rp, struct net_bridge_port, ip6_rlist);
+#endif
 	return hlist_entry_safe(rp, struct net_bridge_port, ip4_rlist);
 }
 
@@ -882,7 +894,7 @@ static inline bool br_ip4_multicast_is_router(struct
net_bridge *br)
 static inline bool br_ip6_multicast_is_router(struct net_bridge *br)
 {
 #if IS_ENABLED(CONFIG_IPV6)
-	return timer_pending(&br->ip4_mc_router_timer);
+	return timer_pending(&br->ip6_mc_router_timer);
 #else
 	return false;
 #endif
-- 
2.31.0

Now that we have split the multicast router state into two, one for IPv4
and one for IPv6, also add individual timers to the mdb netlink router
port dump. Leaving the old timer attribute for backwards compatibility.

Signed-off-by: Linus L?ssing <linus.luessing at c0d3.blue>
---
 include/uapi/linux/if_bridge.h | 2 ++
 net/bridge/br_mdb.c            | 8 +++++++-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/include/uapi/linux/if_bridge.h b/include/uapi/linux/if_bridge.h
index 13d59c5..6b56a75 100644
--- a/include/uapi/linux/if_bridge.h
+++ b/include/uapi/linux/if_bridge.h
@@ -627,6 +627,8 @@ enum {
 	MDBA_ROUTER_PATTR_UNSPEC,
 	MDBA_ROUTER_PATTR_TIMER,
 	MDBA_ROUTER_PATTR_TYPE,
+	MDBA_ROUTER_PATTR_INET_TIMER,
+	MDBA_ROUTER_PATTR_INET6_TIMER,
 	__MDBA_ROUTER_PATTR_MAX
 };
 #define MDBA_ROUTER_PATTR_MAX (__MDBA_ROUTER_PATTR_MAX - 1)
diff --git a/net/bridge/br_mdb.c b/net/bridge/br_mdb.c
index 10c416c..3f839a8 100644
--- a/net/bridge/br_mdb.c
+++ b/net/bridge/br_mdb.c
@@ -79,7 +79,13 @@ static int br_rports_fill_info(struct sk_buff *skb, struct
netlink_callback *cb,
 		    nla_put_u32(skb, MDBA_ROUTER_PATTR_TIMER,
 				max(ip4_timer, ip6_timer)) ||
 		    nla_put_u8(skb, MDBA_ROUTER_PATTR_TYPE,
-			       p->multicast_router)) {
+			       p->multicast_router) ||
+		    (have_ip4_mc_rtr &&
+		     nla_put_u32(skb, MDBA_ROUTER_PATTR_INET_TIMER,
+				 ip4_timer)) ||
+		    (have_ip6_mc_rtr &&
+		     nla_put_u32(skb, MDBA_ROUTER_PATTR_INET6_TIMER,
+				 ip6_timer))) {
 			nla_nest_cancel(skb, port_nest);
 			goto fail;
 		}
-- 
2.31.0

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 L?ssing <linus.luessing at c0d3.blue>
---
 include/linux/if_bridge.h |  8 ++++++
 net/bridge/br_multicast.c | 55 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 63 insertions(+)

diff --git a/include/linux/if_bridge.h b/include/linux/if_bridge.h
index 2cc3503..12e9a32 100644
--- a/include/linux/if_bridge.h
+++ b/include/linux/if_bridge.h
@@ -67,6 +67,7 @@ int br_multicast_list_adjacent(struct net_device *dev,
 			       struct list_head *br_ip_list);
 bool br_multicast_has_querier_anywhere(struct net_device *dev, int proto);
 bool br_multicast_has_querier_adjacent(struct net_device *dev, int proto);
+bool br_multicast_has_router_adjacent(struct net_device *dev, int proto);
 bool br_multicast_enabled(const struct net_device *dev);
 bool br_multicast_router(const struct net_device *dev);
 int br_mdb_replay(struct net_device *br_dev, struct net_device *dev,
@@ -87,6 +88,13 @@ static inline bool br_multicast_has_querier_adjacent(struct
net_device *dev,
 {
 	return false;
 }
+
+static inline bool br_multicast_has_router_adjacent(struct net_device *dev,
+						    int proto)
+{
+	return true;
+}
+
 static inline bool br_multicast_enabled(const struct net_device *dev)
 {
 	return false;
diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index 4448490..fe21f52 100644
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -4061,6 +4061,61 @@ 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();
+	port = br_port_get_check_rcu(dev);
+	if (!port)
+		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)
 {
-- 
2.31.0

On 13/05/2021 02:19, Linus L?ssing wrote:
> Hi,
> 
> The following patches are splitting the so far combined multicast router
> state in the Linux bridge into two ones, one for IPv4 and one for IPv6,
> for a more fine-grained detection of multicast routers. This avoids
> sending IPv4 multicast packets to an IPv6-only multicast router and 
> avoids sending IPv6 multicast packets to an IPv4-only multicast router.
> This also allows batman-adv to make use of the now split information in
> the final patch.
> 
> The first eight patches prepare the bridge code to avoid duplicate
> code or IPv6-#ifdef clutter for the multicast router state split. And 
> contain no functional changes yet.
> 
> The ninth patch then implements the IPv4+IPv6 multicast router state
> split.
> 
> Patch number ten adds IPv4+IPv6 specific timers to the mdb netlink
> router port dump, so that the timers validity can be checked individually
> from userspace.
> 
> The final, eleventh patch exports this now per protocol family multicast
> router state so that batman-adv can then later make full use of the 
> Multicast Router Discovery (MRD) support in the Linux bridge. The 
> batman-adv protocol format currently expects separate multicast router
> states for IPv4 and IPv6, therefore it depends on the first patch.
> batman-adv will then make use of this newly exported functions like
> this[0].
> 
> Regards, Linus
> 
> [0]:
https://git.open-mesh.org/batman-adv.git/shortlog/refs/heads/linus/multicast-routeable-mrd
>      ->
https://git.open-mesh.org/batman-adv.git/commit/d4bed3a92427445708baeb1f2d1841c5fb816fd4
> 
Nice work overall, thank you. I hope it was tested well. :)
It'd be great if later you could add some selftests.

Cheers,
 Nik