bridge: vlan: use synchronize_net() when holding RTNL

br_vlan_flush() and nbp_vlan_flush() should use synchronize_net()
instead of syncronize_rcu() to release RTNL sooner.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Nikolay Aleksandrov <razor@blackwall.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/bridge/br_vlan.c

@@ -841,7 +841,7 @@ void br_vlan_flush(struct net_bridge *br)
 	vg = br_vlan_group(br);
 	__vlan_flush(br, NULL, vg);
 	RCU_INIT_POINTER(br->vlgrp, NULL);
-	synchronize_rcu();
+	synchronize_net();
 	__vlan_group_free(vg);
 }
 
@@ -1372,7 +1372,7 @@ void nbp_vlan_flush(struct net_bridge_port *port)
 	vg = nbp_vlan_group(port);
 	__vlan_flush(port->br, port, vg);
 	RCU_INIT_POINTER(port->vlgrp, NULL);
-	synchronize_rcu();
+	synchronize_net();
 	__vlan_group_free(vg);
 }