On Wed, 28 Aug 2013 13:22:51 +0800
Cong Wang [off-list ref] wrote:

+struct ipv6_stub {
+	int (*ipv6_sock_mc_join)(struct sock *sk, int ifindex,
+				 const struct in6_addr *addr);
+	int (*ipv6_sock_mc_drop)(struct sock *sk, int ifindex,
+				 const struct in6_addr *addr);
+	int (*ipv6_dst_lookup)(struct sock *sk, struct dst_entry **dst,
+				struct flowi6 *fl6);
+	void (*udpv6_encap_enable)(void);
+};
+extern const struct ipv6_stub *ipv6_stub __read_mostly;
+

Since IPv6 really can't ever be safely unloaded. why not:
 * admit that, and get rid of ipv6_module exit.
 * then this stub can be a static const table.

You see virtual function tables that are writeable are potential malware
targets, although eliminating all of them is impossible, I hate to
see adding new ones.