bridge: Export VLAN filtering state

It's useful for drivers supporting bridge offload to be able to query
the bridge's VLAN filtering state.

Currently, upon enslavement to a bridge master, the offloading driver
will only learn about the bridge's VLAN filtering state after the bridge
device was already linked with its slave.

Being able to query the bridge's VLAN filtering state allows such
drivers to forbid enslavement in case resource couldn't be allocated for
a VLAN-aware bridge and also choose the correct initialization routine
for the enslaved port, which is dependent on the bridge type.

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Reviewed-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/if_bridge.h

@@ -80,4 +80,13 @@ static inline bool br_multicast_has_querier_adjacent(struct net_device *dev,
 }
 #endif
 
+#if IS_ENABLED(CONFIG_BRIDGE) && IS_ENABLED(CONFIG_BRIDGE_VLAN_FILTERING)
+bool br_vlan_enabled(const struct net_device *dev);
+#else
+static inline bool br_vlan_enabled(const struct net_device *dev)
+{
+	return false;
+}
+#endif
+
 #endif

net/bridge/br_if.c

@@ -138,7 +138,7 @@ void br_manage_promisc(struct net_bridge *br)
 	/* If vlan filtering is disabled or bridge interface is placed
 	 * into promiscuous mode, place all ports in promiscuous mode.
 	 */
-	if ((br->dev->flags & IFF_PROMISC) || !br_vlan_enabled(br))
+	if ((br->dev->flags & IFF_PROMISC) || !br_vlan_enabled(br->dev))
 		set_all = true;
 
 	list_for_each_entry(p, &br->port_list, list) {

net/bridge/br_mdb.c

@@ -599,7 +599,7 @@ static int br_mdb_add(struct sk_buff *skb, struct nlmsghdr *nlh,
 		return -EINVAL;
 
 	vg = nbp_vlan_group(p);
-	if (br_vlan_enabled(br) && vg && entry->vid == 0) {
+	if (br_vlan_enabled(br->dev) && vg && entry->vid == 0) {
 		list_for_each_entry(v, &vg->vlan_list, vlist) {
 			entry->vid = v->vid;
 			err = __br_mdb_add(net, br, entry);
@@ -694,7 +694,7 @@ static int br_mdb_del(struct sk_buff *skb, struct nlmsghdr *nlh,
 		return -EINVAL;
 
 	vg = nbp_vlan_group(p);
-	if (br_vlan_enabled(br) && vg && entry->vid == 0) {
+	if (br_vlan_enabled(br->dev) && vg && entry->vid == 0) {
 		list_for_each_entry(v, &vg->vlan_list, vlist) {
 			entry->vid = v->vid;
 			err = __br_mdb_del(br, entry);

net/bridge/br_netlink.c

@@ -1251,7 +1251,7 @@ static int br_fill_info(struct sk_buff *skb, const struct net_device *brdev)
 	u32 ageing_time = jiffies_to_clock_t(br->ageing_time);
 	u32 stp_enabled = br->stp_enabled;
 	u16 priority = (br->bridge_id.prio[0] << 8) | br->bridge_id.prio[1];
-	u8 vlan_enabled = br_vlan_enabled(br);
+	u8 vlan_enabled = br_vlan_enabled(br->dev);
 	u64 clockval;
 
 	clockval = br_timer_value(&br->hello_timer);

net/bridge/br_private.h

@@ -854,10 +854,6 @@ static inline u16 br_get_pvid(const struct net_bridge_vlan_group *vg)
 	return vg->pvid;
 }
 
-static inline int br_vlan_enabled(struct net_bridge *br)
-{
-	return br->vlan_enabled;
-}
 #else
 static inline bool br_allowed_ingress(const struct net_bridge *br,
 				      struct net_bridge_vlan_group *vg,
@@ -945,11 +941,6 @@ static inline u16 br_get_pvid(const struct net_bridge_vlan_group *vg)
 	return 0;
 }
 
-static inline int br_vlan_enabled(struct net_bridge *br)
-{
-	return 0;
-}
-
 static inline int __br_vlan_filter_toggle(struct net_bridge *br,
 					  unsigned long val)
 {

net/bridge/br_vlan.c

@@ -706,6 +706,14 @@ int br_vlan_filter_toggle(struct net_bridge *br, unsigned long val)
 	return __br_vlan_filter_toggle(br, val);
 }
 
+bool br_vlan_enabled(const struct net_device *dev)
+{
+	struct net_bridge *br = netdev_priv(dev);
+
+	return !!br->vlan_enabled;
+}
+EXPORT_SYMBOL_GPL(br_vlan_enabled);
+
 int __br_vlan_set_proto(struct net_bridge *br, __be16 proto)
 {
 	int err = 0;