On Fri, Feb 06, 2026 at 03:52:17AM +0100, Linus Lüssing wrote:
> @@ -1095,23 +1095,25 @@ static void br_ip6_multicast_update_active(struct
> net_bridge_mcast *brmctx,
> {
> #if IS_ENABLED(CONFIG_IPV6)
> if (force_inactive)
> - brmctx->ip6_active = false;
> + WRITE_ONCE(brmctx->ip6_active, false);
> else
> - brmctx->ip6_active = br_ip6_multicast_querier_exists(brmctx);
> + WRITE_ONCE(brmctx->ip6_active,
> br_ip6_multicast_querier_exists(brmctx));
> #endif
> }
>
> static void br_multicast_notify_active(struct net_bridge_mcast *brmctx,
> bool ip4_active_old, bool ip6_active_old)
> {
> - if (brmctx->ip4_active == ip4_active_old &&
> - brmctx->ip6_active == ip6_active_old)
> + int ip4_active = READ_ONCE(brmctx->ip4_active);
> + int ip6_active = READ_ONCE(brmctx->ip6_active);
I believe that this is unnecessary since we are holding the lock and it
will confuse people reading the code. We only need the READ_ONCE() later
on in the data path
> +
> + if (ip4_active == ip4_active_old &&
> + ip6_active == ip6_active_old)
> return;
>
> br_info(brmctx->br, "mc_active changed, vid: %i: v4: %i->%i, v6:
> %i->%i\n",
> brmctx->vlan ? brmctx->vlan->vid : -1,
> - ip4_active_old, brmctx->ip4_active,
> - ip6_active_old, brmctx->ip6_active);
> + ip4_active_old, ip4_active, ip6_active_old, ip6_active);
> }
>
> /**
> @@ -1136,7 +1138,8 @@ static void br_multicast_notify_active(struct
> net_bridge_mcast *brmctx,
> */
> static void br_multicast_update_active(struct net_bridge_mcast *brmctx)
> {
> - bool ip4_active_old = brmctx->ip4_active, ip6_active_old =
> brmctx->ip6_active;
> + bool ip4_active_old = READ_ONCE(brmctx->ip4_active);
> + bool ip6_active_old = READ_ONCE(brmctx->ip6_active);
Same
> bool force_inactive = false;
>
> lockdep_assert_held_once(&brmctx->br->multicast_lock);
> @@ -4266,13 +4269,13 @@ void br_multicast_ctx_init(struct net_bridge *br,
> brmctx->multicast_membership_interval = 260 * HZ;
>
> brmctx->ip4_querier.port_ifidx = 0;
> - brmctx->ip4_active = 0;
> + WRITE_ONCE(brmctx->ip4_active, 0);
> seqcount_spinlock_init(&brmctx->ip4_querier.seq, &br->multicast_lock);
> brmctx->multicast_igmp_version = 2;
> #if IS_ENABLED(CONFIG_IPV6)
> brmctx->multicast_mld_version = 1;
> brmctx->ip6_querier.port_ifidx = 0;
> - brmctx->ip6_active = 0;
> + WRITE_ONCE(brmctx->ip6_active, 0);
> seqcount_spinlock_init(&brmctx->ip6_querier.seq, &br->multicast_lock);
> #endif
>
> --
> 2.51.0
>
