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net: bridge: Flush multicast groups when snooping is disabled 

When forwarding multicast packets, the bridge takes MDB into account when
IGMP / MLD snooping is enabled. Currently, when snooping is disabled, the
MDB is retained, even though it is not used anymore.

At the same time, during the time that snooping is disabled, the IGMP / MLD
control packets are obviously ignored, and after the snooping is reenabled,
the administrator has to assume it is out of sync. In particular, missed
join and leave messages would lead to traffic being forwarded to wrong
interfaces.

Keeping the MDB entries around thus serves no purpose, and just takes
memory. Note also that disabling per-VLAN snooping does actually flush the
relevant MDB entries.

This patch flushes non-permanent MDB entries as global snooping is
disabled.

Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Acked-by: Nikolay Aleksandrov <razor@blackwall.org>
Link: https://patch.msgid.link/5e992df1bb93b88e19c0ea5819e23b669e3dde5d.1761228273.git.petrm@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
pull/1354/merge
Petr Machata 2025-10-23 16:45:37 +02:00 committed by Jakub Kicinski
parent 5f30bc4706
commit 68800bbf58
1 changed files with 9 additions and 0 deletions
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9
net/bridge/br_multicast.c
View File

@ -4649,6 +4649,14 @@ static void br_multicast_start_querier(struct net_bridge_mcast *brmctx,
rcu_read_unlock();
}
static void br_multicast_del_grps(struct net_bridge *br)
{
struct net_bridge_port *port;
list_for_each_entry(port, &br->port_list, list)
__br_multicast_disable_port_ctx(&port->multicast_ctx);
}
int br_multicast_toggle(struct net_bridge *br, unsigned long val,
struct netlink_ext_ack *extack)
{
@ -4669,6 +4677,7 @@ int br_multicast_toggle(struct net_bridge *br, unsigned long val,
br_opt_toggle(br, BROPT_MULTICAST_ENABLED, !!val);
if (!br_opt_get(br, BROPT_MULTICAST_ENABLED)) {
change_snoopers = true;
br_multicast_del_grps(br);
goto unlock;
}