This is mainly for switchdev and DSA later: To ensure that we switch
to inactive before destroying a bridge interface. A switchdev/DSA driver
might have allocated resources after we switched to an enabled multicast
active state. This gives switchdev/DSA drivers a chance to free these
resources again when we destroy the bridge (later).

Putting it into the ndo_stop / bridge interface down part instead of the
ndo_uninit / bridge destroy part though for a better semantic match. If
the bridge interface is down / stopped then it is also inactive.

No functional change for the fast/data path.

Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>
---
 include/uapi/linux/if_link.h |  8 ++++----
 net/bridge/br_multicast.c    | 10 ++++++++++
 2 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/include/uapi/linux/if_link.h b/include/uapi/linux/if_link.h
index d68eeff21b73..4ce9ddee94e8 100644
--- a/include/uapi/linux/if_link.h
+++ b/include/uapi/linux/if_link.h
@@ -748,14 +748,14 @@ enum in6_addr_gen_mode {
  * @IFLA_BR_MCAST_ACTIVE_V4
  *   Bridge IPv4 mcast active state, read only.
  *
- *   1 if *IFLA_BR_MCAST_SNOOPING* is enabled and an IGMP querier is present,
- *   0 otherwise.
+ *   1 if *IFLA_BR_MCAST_SNOOPING* is enabled, an IGMP querier is present
+ *   and the bridge interface is up, 0 otherwise.
  *
  * @IFLA_BR_MCAST_ACTIVE_V6
  *   Bridge IPv6 mcast active state, read only.
  *
- *   1 if *IFLA_BR_MCAST_SNOOPING* is enabled and an MLD querier is present,
- *   0 otherwise.
+ *   1 if *IFLA_BR_MCAST_SNOOPING* is enabled, an MLD querier is present
+ *   and the bridge interface is up, 0 otherwise.
  */
 enum {
 	IFLA_BR_UNSPEC,
diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index 2a2f54009e0f..7a32c6bed111 100644
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -1124,6 +1124,7 @@ static void br_multicast_notify_active(struct net_bridge_mcast *brmctx,
  *
  * The multicast active state is set, per protocol family, if:
  *
+ * - the bridge interface is up
  * - multicast snooping is enabled
  * - an IGMP/MLD querier is present
  * - for own IPv6 MLD querier: an IPv6 address is configured on the bridge
@@ -1140,6 +1141,9 @@ static void br_multicast_update_active(struct net_bridge_mcast *brmctx)
 
 	lockdep_assert_held_once(&brmctx->br->multicast_lock);
 
+	if (!netif_running(brmctx->br->dev))
+		force_inactive = true;
+
 	if (!br_opt_get(brmctx->br, BROPT_MULTICAST_ENABLED))
 		force_inactive = true;
 
@@ -4412,6 +4416,9 @@ static void __br_multicast_open(struct net_bridge_mcast *brmctx)
 #if IS_ENABLED(CONFIG_IPV6)
 	__br_multicast_open_query(brmctx->br, &brmctx->ip6_own_query);
 #endif
+
+	/* bridge interface is up, maybe set multicast state to active */
+	br_multicast_update_active(brmctx);
 }
 
 void br_multicast_open(struct net_bridge *br)
@@ -4452,6 +4459,9 @@ static void __br_multicast_stop(struct net_bridge_mcast *brmctx)
 	timer_shutdown(&brmctx->ip6_other_query.delay_timer);
 	timer_shutdown(&brmctx->ip6_own_query.timer);
 #endif
+
+	/* bridge interface is down, set multicast state to inactive */
+	br_multicast_update_active(brmctx);
 }
 
 void br_multicast_update_vlan_mcast_ctx(struct net_bridge_vlan *v, u8 state)
-- 
2.51.0