commit 7ec75c582e639d956ce3afd499f67febe6f902a4
Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Date:   Tue Apr 27 06:22:01 2010 +0000

    net: suppress RCU lockdep false positive in twsk_net()
    
    Calls to twsk_net() are in some cases protected by reference counting
    as an alternative to RCU protection.  Cases covered by reference counts
    include __inet_twsk_kill(), inet_twsk_free(), inet_twdr_do_twkill_work(),
    inet_twdr_twcal_tick(), and tcp_timewait_state_process().  RCU is used
    by inet_twsk_purge().  Locking is used by established_get_first()
    and established_get_next().  Finally, __inet_twsk_hashdance() is an
    initialization case.
    
    It appears to be non-trivial to locate the appropriate locks and
    reference counts from within twsk_net(), so used rcu_dereference_raw().
    
    Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
    Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/inet_timewait_sock.h b/include/net/inet_timewait_sock.h
index 79f67ea..a066fdd 100644
--- a/include/net/inet_timewait_sock.h
+++ b/include/net/inet_timewait_sock.h
@@ -224,7 +224,9 @@ static inline
 struct net *twsk_net(const struct inet_timewait_sock *twsk)
 {
 #ifdef CONFIG_NET_NS
-	return rcu_dereference(twsk->tw_net);
+	return rcu_dereference_raw(twsk->tw_net); /* protected by locking, */
+						  /* reference counting, */
+						  /* initialization, or RCU. */
 #else
 	return &init_net;
 #endif