commit 
b099ce2602d806 (net: Batch inet_twsk_purge) added rcu protection
on tw_net for no obvious reason.
struct net are refcounted anyway since timewait sockets escape from rcu
protected sections. tw_net stay valid for the whole timwait lifetime.
This also removes a lot of sparse errors.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
CC: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
 
 static inline
 struct net *twsk_net(const struct inet_timewait_sock *twsk)
 {
-#ifdef CONFIG_NET_NS
-       return rcu_dereference_raw(twsk->tw_net); /* protected by locking, */
-                                                 /* reference counting, */
-                                                 /* initialization, or RCU. */
-#else
-       return &init_net;
-#endif
+       return read_pnet(&twsk->tw_net);
 }
 
 static inline
 void twsk_net_set(struct inet_timewait_sock *twsk, struct net *net)
 {
-#ifdef CONFIG_NET_NS
-       rcu_assign_pointer(twsk->tw_net, net);
-#endif
+       write_pnet(&twsk->tw_net, net);
 }
 #endif /* _INET_TIMEWAIT_SOCK_ */