[TWSK]: Grab the module refcount for timewait sockets

This is required to avoid unloading a module that has active timewait
sockets, such as DCCP.

Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/inet_timewait_sock.c

@@ -111,6 +111,7 @@ struct inet_timewait_sock *inet_twsk_alloc(const struct sock *sk, const int stat
 		tw->tw_prot	    = sk->sk_prot_creator;
 		atomic_set(&tw->tw_refcnt, 1);
 		inet_twsk_dead_node_init(tw);
+		__module_get(tw->tw_prot->owner);
 	}
 
 	return tw;