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List:       linux-stable-commits
Subject:    patch tcp-fix-config_tcp_md5sig-config_preempt-timer-bug.patch added to 2.6.27-stable tree
From:       <gregkh () suse ! de>
Date:       2010-02-12 23:45:55
Message-ID: 12660183552638 () kroah ! org
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This is a note to let you know that we have just queued up the patch titled

    Subject: tcp: fix CONFIG_TCP_MD5SIG + CONFIG_PREEMPT timer BUG()

to the 2.6.27-stable tree.  Its filename is

    tcp-fix-config_tcp_md5sig-config_preempt-timer-bug.patch

A git repo of this tree can be found at 
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary


From 657e9649e745b06675aa5063c84430986cdc3afa Mon Sep 17 00:00:00 2001
From: Robert Varga <nite@hq.alert.sk>
Date: Tue, 15 Sep 2009 23:49:21 -0700
Subject: tcp: fix CONFIG_TCP_MD5SIG + CONFIG_PREEMPT timer BUG()

From: Robert Varga <nite@hq.alert.sk>

commit 657e9649e745b06675aa5063c84430986cdc3afa upstream.

I have recently came across a preemption imbalance detected by:

<4>huh, entered ffffffff80644630 with preempt_count 00000102, exited with 00000101?
<0>------------[ cut here ]------------
<2>kernel BUG at /usr/src/linux/kernel/timer.c:664!
<0>invalid opcode: 0000 [1] PREEMPT SMP

with ffffffff80644630 being inet_twdr_hangman().

This appeared after I enabled CONFIG_TCP_MD5SIG and played with it a
bit, so I looked at what might have caused it.

One thing that struck me as strange is tcp_twsk_destructor(), as it
calls tcp_put_md5sig_pool() -- which entails a put_cpu(), causing the
detected imbalance. Found on 2.6.23.9, but 2.6.31 is affected as well,
as far as I can tell.

Signed-off-by: Robert Varga <nite@hq.alert.sk>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 net/ipv4/tcp_minisocks.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -362,7 +362,7 @@ void tcp_twsk_destructor(struct sock *sk
 #ifdef CONFIG_TCP_MD5SIG
 	struct tcp_timewait_sock *twsk = tcp_twsk(sk);
 	if (twsk->tw_md5_keylen)
-		tcp_put_md5sig_pool();
+		tcp_free_md5sig_pool();
 #endif
 }
 


Patches currently in stable-queue which might be from nite@hq.alert.sk are

queue-2.6.27/tcp-fix-config_tcp_md5sig-config_preempt-timer-bug.patch
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