Resoves bz 642905

kernel.spec

@@ -825,6 +825,9 @@ Patch12590: sctp-do-not-reset-the-packet-during-sctp_packet_config.patch
 #Bonding sysfs WARN_ON (bz 604630)
 Patch12591: linux-2.6-bonding-sysfs-warning.patch
 
+#twsock rcu warning fix (bz 642905)
+Patch12592: linux-2.6-twsock-rcu-lockdep-warn.patch
+
 %endif
 
 BuildRoot: %{_tmppath}/kernel-%{KVERREL}-root
@@ -1559,6 +1562,9 @@ ApplyPatch sctp-do-not-reset-the-packet-during-sctp_packet_config.patch
 # BZ 604630
 ApplyPatch linux-2.6-bonding-sysfs-warning.patch
 
+# BZ 642905
+ApplyPatch linux-2.6-twsock-rcu-lockdep-warn.patch
+
 # END OF PATCH APPLICATIONS
 
 %endif
@@ -2180,6 +2186,9 @@ fi
 
 
 %changelog
+* Thu Oct 14 2010 Neil Horman <nhorman@redhat.com>
+- Fix rcu warning in twsock_net (bz 642905)
+
 * Wed Oct 06 2010 Neil Horman <nhorman@redhat.com>
 - Fix WARN_ON when you try to create an exiting bond in bond_masters
 

linux-2.6-twsock-rcu-lockdep-warn.patch

@@ -0,0 +1,36 @@
+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