--- zzzz-none-000/linux-5.15.111/net/l2tp/l2tp_core.h	2023-05-11 14:00:40.000000000 +0000
+++ puma7-atom-6670-761/linux-5.15.111/net/l2tp/l2tp_core.h	2024-02-07 10:23:30.000000000 +0000
@@ -52,6 +52,7 @@
 	unsigned int		lns_mode:1;	/* behave as LNS?
 						 * LAC enables sequence numbers under LNS control.
 						 */
+	u16			offset;		/* offset to payload */
 	u16			l2specific_type; /* Layer 2 specific type */
 	u8			cookie[8];	/* optional cookie */
 	int			cookie_len;	/* 0, 4 or 8 bytes */
@@ -78,6 +79,8 @@
 	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_type;
 	u16			hdr_len;
 	u32			nr;		/* session NR state (receive) */
@@ -343,4 +346,10 @@
 #define MODULE_ALIAS_L2TP_PWTYPE(type) \
 	MODULE_ALIAS("net-l2tp-type-" __stringify(type))
 
+/* Notify users about changes backported from kernel 4.15 because the
+ * interface of l2tp_session_get changed by this and lt2p_session_find
+ * was removed.
+ */
+#define AVM_L2TP_BACKPORT_4_15
+
 #endif /* _L2TP_CORE_H_ */