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    | 12 ++++++++++++
 2 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/include/uapi/linux/if_link.h b/include/uapi/linux/if_link.h
index d963be8679b5..679368784643 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 1059984d8147..cb78f9555db6 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 link-local address is configured on the
@@ -1142,6 +1143,11 @@ 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;
+		goto update;
+	}
+
 	if (!br_opt_get(brmctx->br, BROPT_MULTICAST_ENABLED)) {
 		force_inactive = true;
 		goto update;
@@ -4431,6 +4437,9 @@ 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);
 }
 
 static void br_multicast_open_locked(struct net_bridge *br)
@@ -4478,6 +4487,9 @@ 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)
-- 
2.53.0

On Sat, Mar 07, 2026 at 05:45:44AM +0100, Linus Lüssing wrote:
> @@ -4431,6 +4437,9 @@ 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);
>  }
>  
>  static void br_multicast_open_locked(struct net_bridge *br)
> @@ -4478,6 +4487,9 @@ 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 */

Noticed this while reviewing patch #14: The comments about the interface
being up / down are inaccurate when __br_multicast_{open,stop}() are
called for a per-VLAN multicast context

On Sat, Mar 07, 2026 at 05:45:44AM +0100, Linus Lüssing wrote:
> @@ -4478,6 +4487,9 @@ 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);
>  }

This suffers from the same problem that I already mentioned.
__br_multicast_stop() is only called for VLANs that were added on the
bridge. For the rest it does not update the active state. You can
reproduce with [1].

[1]
#!/bin/bash

for ns in ns0 ns1; do
	ip netns del $ns &> /dev/null
	ip netns add $ns
	ip -n $ns link set dev lo up
done

ip -n ns0 link add name veth0 type veth peer name veth1 netns ns1

ip -n ns0 link add name br0 up type bridge vlan_filtering 1 mcast_snooping 1 mcast_vlan_snooping 1
ip -n ns1 link add name br1 up type bridge vlan_filtering 1 mcast_snooping 1 mcast_vlan_snooping 1

ip -n ns0 link set dev veth0 up master br0
ip -n ns1 link set dev veth1 up master br1

bridge -n ns0 vlan add vid 10 dev veth0 master
bridge -n ns1 vlan add vid 10 dev veth1 master

sleep 5

bridge -n ns0 vlan global set vid 10 dev br0 mcast_snooping 1 mcast_query_response_interval 100 mcast_querier 1
bridge -n ns1 vlan global set vid 10 dev br1 mcast_snooping 1 mcast_query_response_interval 100 mcast_querier 0

sleep 5

bridge -n ns1 -j -p vlan global show dev br1 vid 10 | jq '.[]["vlans"][]["mcast_active_v4"]'

ip -n ns1 link set dev br1 down
sleep 5
bridge -n ns1 -j -p vlan global show dev br1 vid 10 | jq '.[]["vlans"][]["mcast_active_v4"]'