l2tp: purge session reorder queue on delete

Add calls to l2tp_session_queue_purge as a part of l2tp_tunnel_closeall
and l2tp_session_delete.  Pseudowire implementations which are deleted only
via. l2tp_core l2tp_session_delete calls can dispense with their own code for
flushing the reorder queue.
Signed-off-by: NTom Parkin <tparkin@katalix.com>
Signed-off-by: NJames Chapman <jchapman@katalix.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/l2tp/l2tp_core.c

@@ -1373,6 +1373,8 @@ void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel)
 				synchronize_rcu();
 			}
 
+			l2tp_session_queue_purge(session);
+
 			if (session->session_close != NULL)
 				(*session->session_close)(session);
 
@@ -1813,6 +1815,8 @@ EXPORT_SYMBOL_GPL(l2tp_session_free);
  */
 int l2tp_session_delete(struct l2tp_session *session)
 {
+	l2tp_session_queue_purge(session);
+
 	if (session->session_close != NULL)
 		(*session->session_close)(session);