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Date: Wed, 4 Jan 2012 10:20:41 -0800
From: Tejun Heo <tj@kernel.org>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Kernel development list <linux-kernel@vger.kernel.org>,
        Eric Biederman <ebiederm@xmission.com>,
        Greg Kroah-Hartman <gregkh@suse.de>,
        Kay Sievers <kay.sievers@vrfy.org>
Subject: Re: Sysfs attributes racing with unregistration
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 <Pine.LNX.4.44L0.1201041300130.1505-100000@iolanthe.rowland.org>
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Hello,

On Wed, Jan 04, 2012 at 01:13:41PM -0500, Alan Stern wrote:
> Now, looking through the code, I wonder why sysfs_{get,put}_active() 
> and sysfs_deactivate() don't use a real rwsem.  Why go to all the 
> effort of imitating one?  Is it just to save space?

Hmmm... maybe there was something which prevented that or maybe I was
just being stupid.  I don't really remember.  Space is a fairly
important consideration too.  Depending on configuration, there can be
a LOT of sysfs_dirents and memory consumption from sysfs has been a
real problem.

Thanks.

-- 
tejun