If we are the only potential MLD querier but don't have an IPv6
link-local address configured on our bridge interface then we can't
create a valid MLD query and in turn can't reliably receive MLD reports
and can't build a complete MDB. Hence disable the new multicast active
state variable then. Or reenable it if an IPv6 link-local address
became available.

No functional change for the fast/data path yet.

Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>
---
 net/bridge/br_multicast.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index 2e5b5281e484..b689e62b9e74 100644
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -1112,6 +1112,7 @@ static void br_ip6_multicast_update_active(struct net_bridge_mcast *brmctx,
  * The multicast active state is set, per protocol family, if:
  *
  * - an IGMP/MLD querier is present
+ * - for own IPv6 MLD querier: an IPv6 address is configured on the bridge
  *
  * And is unset otherwise.
  *
@@ -1206,10 +1207,12 @@ static struct sk_buff *br_ip6_multicast_alloc_query(struct net_bridge_mcast *brm
 			       &ip6h->daddr, 0, &ip6h->saddr)) {
 		kfree_skb(skb);
 		br_opt_toggle(brmctx->br, BROPT_HAS_IPV6_ADDR, false);
+		br_multicast_update_active(brmctx);
 		return NULL;
 	}
 
 	br_opt_toggle(brmctx->br, BROPT_HAS_IPV6_ADDR, true);
+	br_multicast_update_active(brmctx);
 	ipv6_eth_mc_map(&ip6h->daddr, eth->h_dest);
 
 	hopopt = (u8 *)(ip6h + 1);
-- 
2.50.1