[PATCH v3 net-next 08/14] net: bridge: mst: Add helper to check if MST is enabled

[Tobias Waldekranz <tobias@xxxxxxxxxxxxxx>]

This is useful for switchdev drivers that might want to refuse to join
a bridge where MST is enabled, if the hardware can't support it.

Signed-off-by: Tobias Waldekranz <tobias@xxxxxxxxxxxxxx>
---
 include/linux/if_bridge.h | 5 +++++
 net/bridge/br_mst.c       | 9 +++++++++
 2 files changed, 14 insertions(+)

diff --git a/include/linux/if_bridge.h b/include/linux/if_bridge.h
index 46e6327fef06..5dbab0a280a6 100644
--- a/include/linux/if_bridge.h
+++ b/include/linux/if_bridge.h
@@ -119,6 +119,7 @@ int br_vlan_get_info(const struct net_device *dev, u16 vid,
 		     struct bridge_vlan_info *p_vinfo);
 int br_vlan_get_info_rcu(const struct net_device *dev, u16 vid,
 			 struct bridge_vlan_info *p_vinfo);
+bool br_mst_enabled(struct net_device *dev);
 int br_mst_get_info(struct net_device *dev, u16 msti, unsigned long *vids);
 #else
 static inline bool br_vlan_enabled(const struct net_device *dev)
@@ -152,6 +153,10 @@ static inline int br_vlan_get_info_rcu(const struct net_device *dev, u16 vid,
 {
 	return -EINVAL;
 }
+static inline bool br_mst_enabled(struct net_device *dev)
+{
+	return false;
+}
 static inline int br_mst_get_info(struct net_device *dev, u16 msti,
 				  unsigned long *vids)
 {
diff --git a/net/bridge/br_mst.c b/net/bridge/br_mst.c
index eb18dbd5838f..e5ab2ce451c2 100644
--- a/net/bridge/br_mst.c
+++ b/net/bridge/br_mst.c
@@ -13,6 +13,15 @@
 
 DEFINE_STATIC_KEY_FALSE(br_mst_used);
 
+bool br_mst_enabled(struct net_device *dev)
+{
+	if (!netif_is_bridge_master(dev))
+		return false;
+
+	return br_opt_get(netdev_priv(dev), BROPT_MST_ENABLED);
+}
+EXPORT_SYMBOL(br_mst_enabled);
+
 int br_mst_get_info(struct net_device *dev, u16 msti, unsigned long *vids)
 {
 	struct net_bridge_vlan_group *vg;
-- 
2.25.1