From 91035f0b7d89291af728b6f3e370c3be58fcbe1b Mon Sep 17 00:00:00 2001
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Fri, 18 Feb 2011 22:35:56 +0000
Subject: [PATCH] tcp: fix inet_twsk_deschedule()

Eric W. Biederman reported a lockdep splat in inet_twsk_deschedule()

This is caused by inet_twsk_purge(), run from process context,
and commit 575f4cd5a5b6394577 (net: Use rcu lookups in inet_twsk_purge.)
removed the BH disabling that was necessary.

Add the BH disabling but fine grained, right before calling
inet_twsk_deschedule(), instead of whole function.

With help from Linus Torvalds and Eric W. Biederman

Reported-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
CC: Daniel Lezcano <daniel.lezcano@free.fr>
CC: Pavel Emelyanov <xemul@openvz.org>
CC: Arnaldo Carvalho de Melo <acme@redhat.com>
CC: stable <stable@kernel.org> (# 2.6.33+)
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 net/ipv4/inet_timewait_sock.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/ipv4/inet_timewait_sock.c b/net/ipv4/inet_timewait_sock.c
index c5af909cf701..3c8dfa16614d 100644
--- a/net/ipv4/inet_timewait_sock.c
+++ b/net/ipv4/inet_timewait_sock.c
@@ -505,7 +505,9 @@ void inet_twsk_purge(struct inet_hashinfo *hashinfo,
 			}
 
 			rcu_read_unlock();
+			local_bh_disable();
 			inet_twsk_deschedule(tw, twdr);
+			local_bh_enable();
 			inet_twsk_put(tw);
 			goto restart_rcu;
 		}