To make users (e.g. batman-adv soon) load- and runnable even if the bridge was compiled without snooping capabilities - or even if the kernel was compiled without any bridge code at all.

Signed-off-by: Linus Lüssing linus.luessing@web.de --- include/linux/if_bridge.h | 14 ++++++++++++++ 1 file changed, 14 insertions(+)

diff --git a/include/linux/if_bridge.h b/include/linux/if_bridge.h index fd22789..e0c575c 100644 --- a/include/linux/if_bridge.h +++ b/include/linux/if_bridge.h @@ -36,8 +36,22 @@ extern void brioctl_set(int (*ioctl_hook)(struct net *, unsigned int, void __use

typedef int br_should_route_hook_t(struct sk_buff *skb); extern br_should_route_hook_t __rcu *br_should_route_hook; + +#if IS_ENABLED(CONFIG_BRIDGE) && IS_ENABLED(CONFIG_BRIDGE_IGMP_SNOOPING) int br_multicast_list_adjacent(struct net_device *dev, struct list_head *br_ip_list); bool br_multicast_has_querier_adjacent(struct net_device *dev, int proto); +#else +static inline int br_multicast_list_adjacent(struct net_device *dev, + struct list_head *br_ip_list) +{ + return 0; +} +static inline bool br_multicast_has_querier_adjacent(struct net_device *dev, + int proto) +{ + return false; +} +#endif

#endif

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 --- include/linux/if_bridge.h | 6 ++++++ net/bridge/br_multicast.c | 37 +++++++++++++++++++++++++++++++++++++ 2 files changed, 43 insertions(+)

diff --git a/include/linux/if_bridge.h b/include/linux/if_bridge.h index e0c575c..808dcb8 100644 --- a/include/linux/if_bridge.h +++ b/include/linux/if_bridge.h @@ -40,6 +40,7 @@ extern br_should_route_hook_t __rcu *br_should_route_hook; #if IS_ENABLED(CONFIG_BRIDGE) && IS_ENABLED(CONFIG_BRIDGE_IGMP_SNOOPING) int br_multicast_list_adjacent(struct net_device *dev, struct list_head *br_ip_list); +bool br_multicast_has_querier_anywhere(struct net_device *dev, int proto); bool br_multicast_has_querier_adjacent(struct net_device *dev, int proto); #else static inline int br_multicast_list_adjacent(struct net_device *dev, @@ -47,6 +48,11 @@ static inline int br_multicast_list_adjacent(struct net_device *dev, { return 0; } +static inline bool br_multicast_has_querier_anywhere(struct net_device *dev, + int proto) +{ + return false; +} static inline bool br_multicast_has_querier_adjacent(struct net_device *dev, int proto) { diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c index abfa0b65..b4845f4 100644 --- a/net/bridge/br_multicast.c +++ b/net/bridge/br_multicast.c @@ -2216,6 +2216,43 @@ unlock: EXPORT_SYMBOL_GPL(br_multicast_list_adjacent);

/** + * br_multicast_has_querier_anywhere - Checks for a querier on a bridge + * @dev: The bridge port providing the bridge on which to check for a querier + * @proto: The protocol family to check for: IGMP -> ETH_P_IP, MLD -> ETH_P_IPV6 + * + * Checks whether the given interface has a bridge on top and if so returns + * true if a valid querier exists anywhere on the bridged link layer. + * Otherwise returns false. + */ +bool br_multicast_has_querier_anywhere(struct net_device *dev, int proto) +{ + struct net_bridge *br; + struct net_bridge_port *port; + struct ethhdr eth; + bool ret = false; + + rcu_read_lock(); + if (!br_port_exists(dev)) + goto unlock; + + port = br_port_get_rcu(dev); + if (!port || !port->br) + goto unlock; + + br = port->br; + + memset(&eth, 0, sizeof(eth)); + eth.h_proto = htons(proto); + + ret = br_multicast_querier_exists(br, &eth); + +unlock: + rcu_read_unlock(); + return ret; +} +EXPORT_SYMBOL_GPL(br_multicast_has_querier_anywhere); + +/** * br_multicast_has_querier_adjacent - Checks for a querier behind a bridge port * @dev: The bridge port adjacent to which to check for a querier * @proto: The protocol family to check for: IGMP -> ETH_P_IP, MLD -> ETH_P_IPV6