From: Liu, Jinsong <jinsong.liu@intel.com>
Date: Tue, 12 Jun 2012 15:11:16 +0000 (+0800)
Subject: xen/mce: schedule a workqueue to avoid sleep in atomic context
X-Git-Tag: v3.6-rc1~123^2~13
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1b2a05516e42149a5e9f0f5aeba2c7fa9574b3f4;p=pandora-kernel.git

xen/mce: schedule a workqueue to avoid sleep in atomic context

copy_to_user might sleep and print a stack trace if it is executed
in an atomic spinlock context. Like this:

(XEN) CMCI: send CMCI to DOM0 through virq
BUG: sleeping function called from invalid context at /home/konradinux/kernel.h:199
in_atomic(): 1, irqs_disabled(): 0, pid: 4581, name: mcelog
Pid: 4581, comm: mcelog Tainted: G           O 3.5.0-rc1upstream-00003-g149000b-dirty #1
 [<ffffffff8109ad9a>] __might_sleep+0xda/0x100
 [<ffffffff81329b0b>] xen_mce_chrdev_read+0xab/0x140
 [<ffffffff81148945>] vfs_read+0xc5/0x190
 [<ffffffff81148b0c>] sys_read+0x4c/0x90
 [<ffffffff815bd039>] system_call_fastpath+0x16

This patch schedule a workqueue for IRQ handler to poll the data,
and use mutex instead of spinlock, so copy_to_user sleep in atomic
context would not occur.

Reported-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Suggested-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Liu, Jinsong <jinsong.liu@intel.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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