From: Frank Li <Frank.Li@freescale.com>
Date: Wed, 6 Feb 2013 14:59:59 +0000 (+0000)
Subject: net: fec: fix spin_lock dead lock
X-Git-Tag: v3.9-rc1~139^2~135
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=85bd1798b24a13462d7b064961e7a9da3bb12db1;p=pandora-kernel.git

net: fec: fix spin_lock dead lock

=========================================================
[ INFO: possible irq lock inversion dependency detected ]
3.8.0-rc5+ #82 Not tainted
---------------------------------------------------------
swapper/0/0 just changed the state of lock:
 (&(&fep->hw_lock)->rlock){..-...}, at: [<8034e2f8>] fec_enet_start_xmit+0x48/0x                      2cc
but this lock took another, SOFTIRQ-unsafe lock in the past:
(prepare_lock){+.+.+.}

and interrupts could create inverse lock ordering between them.
other info that might help us debug this:
Possible interrupt unsafe locking scenario:

CPU0				CPU1
----				----
lock(prepare_lock);
				local_irq_disable()
				lock(&(&fep->hw_lock)->rlock);
				lock(prepare_lock);
<Interrupt>
lock(&(&fep->hw_lock)->rlock);

*** DEADLOCK ***

Signed-off-by: Frank Li <Frank.Li@freescale.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

Reading git-diff-tree failed