[PATCH net-next v4 10/14] net: bridge: mcast: track active state, bridge up/down

Linus Lüssing
2026-03-07T04:46:17Z

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