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 @@
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