From: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Date: Fri, 8 May 2009 08:28:40 +0000 (+0900)
Subject: x86: MCE: make cmci_discover_lock irq-safe
X-Git-Tag: v2.6.30-rc5~2^2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e5299926d7459d9fa7c7f856983147817aedb10e;p=pandora-kernel.git

x86: MCE: make cmci_discover_lock irq-safe

Lockdep reports the warning below when Li tries to offline one cpu:

[  110.835487] =================================
[  110.835616] [ INFO: inconsistent lock state ]
[  110.835688] 2.6.30-rc4-00336-g8c9ed89 #52
[  110.835757] ---------------------------------
[  110.835828] inconsistent {HARDIRQ-ON-W} -> {IN-HARDIRQ-W} usage.
[  110.835908] swapper/0 [HC1[1]:SC0[0]:HE0:SE1] takes:
[  110.835982]  (cmci_discover_lock){?.+...}, at: [<ffffffff80236dc0>] cmci_clear+0x30/0x9b

cmci_clear() can be called via smp_call_function_single().

It is better to disable interrupt while holding cmci_discover_lock,
to turn it into an irq-safe lock - we can deadlock otherwise.

[ Impact: fix possible deadlock in the MCE code ]

Reported-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
LKML-Reference: <4A03ED38.8000700@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Reported-by: Shaohua Li<shaohua.li@intel.com>
---

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