From: Zhang Rui <rui.zhang@intel.com>
Date: Tue, 23 Jun 2009 02:20:29 +0000 (+0800)
Subject: ACPI: fix a deadlock in hotplug case
X-Git-Tag: v2.6.31-rc1~12^2~9^8~1
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c02256be79a1a3557332ac51e653d574a2a7d2b5;p=pandora-kernel.git

ACPI: fix a deadlock in hotplug case

we used to run the hotplug code in keventd_wq.
But when hot removing the ACPI battery device,
power_supply_unregister invokes flush_scheduled_work.
This causes a deadlock. i.e
1. When dock is unplugged, all the hotplug code is run on kevent_wq.
2. the hotplug code removes all the child devices of dock device.
3. removing the child device may invoke flush_scheduled_work
4. flush_scheduled_work waits until all the work on kevent_wq to be
   finished, while this will never be true because the hotplug code
   is running on keventd_wq...

Introduce a new workqueue for hotplug in this patch.
http://bugzilla.kernel.org/show_bug.cgi?id=13533

Tested-by: Paul Martin <pm@debian.org>
Tested-by: Vojtech Gondzala <vojtech.gondzala@gmail.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Reviewed-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Len Brown <len.brown@intel.com>
---

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