netdev - tcp_put_md5sig_pool() from tcp_twsk

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Message-ID: <20090912010401.GA28539@hq.alert.sk>
Date:	Sat, 12 Sep 2009 03:04:01 +0200
From:	Robert Varga <nite@...alert.sk>
To:	netdev@...r.kernel.org
Subject: tcp_put_md5sig_pool() from tcp_twsk_destructor()?

Hi,

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 that
calls tcp_put_md5sig_pool() -- which entails a put_cpu(), which does not
make sense to me -- and would explain the imbalance.

Shouldn't tcp_twsk_destructor() be calling tcp_free_md5sig_pool()
instead?

Please CC: me, as I am not subscribed to the list.

-- 
Bye,
Robert Varga

Reality continues to ruin my life. -- Calvin
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