tree d4247dfb6ac918beb7b515cac71c6f334635a486
parent f941a6d9a9e0612eb807af822b0d1ac004da8175
author Linus Lüssing <linus.luessing@web.de> 1404704477 +0200
committer David S. Miller <davem@davemloft.net> 1404861173 -0700

bridge: export knowledge about the presence of IGMP/MLD queriers

With this patch other modules are able to ask the bridge whether an
IGMP or MLD querier exists on the according, bridged link layer.

Multicast snooping can only be performed if a valid, selected querier
exists on a link.

Just like the bridge only enables its multicast snooping if a querier
exists, e.g. batman-adv too can only activate its multicast
snooping in bridged scenarios if a querier is present.

For instance this export avoids having to reimplement IGMP/MLD
querier message snooping and parsing in e.g. batman-adv, when
multicast optimizations for bridged scenarios are added in the
future.

Signed-off-by: Linus Lüssing <linus.luessing@web.de>
Signed-off-by: David S. Miller <davem@davemloft.net>