l2tp: remove unused tunnel magic field

Since l2tp no longer derives tunnel pointers directly via
sk_user_data, it is no longer useful for l2tp to check tunnel pointers
using a magic feather. Drop the tunnel's magic field.
Signed-off-by: James Chapman <jchapman@katalix.com>
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/l2tp/l2tp_core.c

@@ -1527,7 +1527,6 @@ int l2tp_tunnel_create(int fd, int version, u32 tunnel_id, u32 peer_tunnel_id,
 	tunnel->tunnel_id = tunnel_id;
 	tunnel->peer_tunnel_id = peer_tunnel_id;
 
-	tunnel->magic = L2TP_TUNNEL_MAGIC;
 	sprintf(&tunnel->name[0], "tunl %u", tunnel_id);
 	spin_lock_init(&tunnel->list_lock);
 	tunnel->acpt_newsess = true;

net/l2tp/l2tp_core.h

@@ -16,7 +16,6 @@
 #endif
 
 /* Random numbers used for internal consistency checks of tunnel and session structures */
-#define L2TP_TUNNEL_MAGIC	0x42114DDA
 #define L2TP_SESSION_MAGIC	0x0C04EB7D
 
 struct sk_buff;
@@ -155,8 +154,6 @@ struct l2tp_tunnel_cfg {
  */
 #define L2TP_TUNNEL_NAME_MAX 20
 struct l2tp_tunnel {
-	int			magic;		/* Should be L2TP_TUNNEL_MAGIC */
-
 	unsigned long		dead;
 
 	struct rcu_head rcu;