--- zzzz-none-000/linux-4.9.231/net/l2tp/l2tp_core.h	2020-07-22 07:10:54.000000000 +0000
+++ falcon-5590-729/linux-4.9.231/net/l2tp/l2tp_core.h	2022-03-30 12:03:35.000000000 +0000
@@ -58,6 +58,7 @@
 	int			debug;		/* bitmask of debug message
 						 * categories */
 	u16			vlan_id;	/* VLAN pseudowire only */
+	u16			offset;		/* offset to payload */
 	u16			l2specific_len;	/* Layer 2 specific length */
 	u16			l2specific_type; /* Layer 2 specific type */
 	u8			cookie[8];	/* optional cookie */
@@ -84,6 +85,8 @@
 	int			cookie_len;
 	u8			peer_cookie[8];
 	int			peer_cookie_len;
+	u16			offset;		/* offset from end of L2TP header
+						   to beginning of data */
 	u16			l2specific_len;
 	u16			l2specific_type;
 	u16			hdr_len;