l2tp: export l2tp_tunnel_closeall

l2tp_core internally uses l2tp_tunnel_closeall to close all sessions in a
tunnel when a UDP-encapsulation socket is destroyed.  We need to do something
similar for IP-encapsulation sockets.

Export l2tp_tunnel_closeall as a GPL symbol to enable l2tp_ip and l2tp_ip6 to
call it from their .destroy handlers.

Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: James Chapman <jchapman@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
index ee726a7..287e327 100644
--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -114,7 +114,6 @@
 
 static void l2tp_session_set_header_len(struct l2tp_session *session, int version);
 static void l2tp_tunnel_free(struct l2tp_tunnel *tunnel);
-static void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel);
 
 static inline struct l2tp_net *l2tp_pernet(struct net *net)
 {
@@ -1312,7 +1311,7 @@
 
 /* When the tunnel is closed, all the attached sessions need to go too.
  */
-static void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel)
+void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel)
 {
 	int hash;
 	struct hlist_node *walk;
@@ -1375,6 +1374,7 @@
 	}
 	write_unlock_bh(&tunnel->hlist_lock);
 }
+EXPORT_SYMBOL_GPL(l2tp_tunnel_closeall);
 
 /* Tunnel socket destroy hook for UDP encapsulation */
 static void l2tp_udp_encap_destroy(struct sock *sk)