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Date: Wed, 23 Sep 2009 09:11:27 +0100
From: Jonathan Cameron <jic23@cam.ac.uk>
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To: Zhang Rui <rui.zhang@intel.com>
CC: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       linux-acpi <linux-acpi@vger.kernel.org>,
       Jean Delvare <khali@linux-fr.org>,
       "alan@linux.intel.com" <alan@linux.intel.com>,
       "Cory T. Tusar" <ctusar@videon-central.com>,
       "Trisal, Kalhan" <kalhan.trisal@intel.com>, Len Brown <lenb@kernel.org>,
       Pavel Machek <pavel@ucw.cz>
Subject: Re: [RFC] [PATCH 2/2] ACPI: introduce ACPI ALS device driver
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>> Are there any plausible race conditions associated with doing the allocation this way?
> 
> well, theoretically, yes.
> simultaneous add calls may happen in hotplug case, but I don't think an
> ACPI ALS device supports hotplug.
That would make that point irrelevant!

Thinking further on this. What happens on a box that for some reason repeatedly inserts and
removes this module?

This is the sort of problem idr's are meant to overcome.  They will cost you a bit
in terms of complexity though.