net: Modify sk_alloc to not reference count the netns of kernel sockets.

Now that sk_alloc knows when a kernel socket is being allocated modify
it to not reference count the network namespace of kernel sockets.

Keep track of if a socket needs reference counting by adding a flag to
struct sock called sk_net_refcnt.

Update all of the callers of sock_create_kern to stop using
sk_change_net and sk_release_kernel as those hacks are no longer
needed, to avoid reference counting a kernel socket.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/ip6_udp_tunnel.c b/net/ipv6/ip6_udp_tunnel.c
index 478576b..e1a1136 100644
--- a/net/ipv6/ip6_udp_tunnel.c
+++ b/net/ipv6/ip6_udp_tunnel.c
@@ -19,12 +19,10 @@
 	int err;
 	struct socket *sock = NULL;
 
-	err = sock_create_kern(&init_net, AF_INET6, SOCK_DGRAM, 0, &sock);
+	err = sock_create_kern(net, AF_INET6, SOCK_DGRAM, 0, &sock);
 	if (err < 0)
 		goto error;
 
-	sk_change_net(sock->sk, net);
-
 	udp6_addr.sin6_family = AF_INET6;
 	memcpy(&udp6_addr.sin6_addr, &cfg->local_ip6,
 	       sizeof(udp6_addr.sin6_addr));
@@ -55,7 +53,7 @@
 error:
 	if (sock) {
 		kernel_sock_shutdown(sock, SHUT_RDWR);
-		sk_release_kernel(sock->sk);
+		sock_release(sock);
 	}
 	*sockp = NULL;
 	return err;