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Date: Thu, 28 Feb 2002 01:05:33 +0100
From: Erik Mouw <J.A.K.Mouw@its.tudelft.nl>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Val Henson <val@nmt.edu>, "Randy.Dunlap" <rddunlap@osdl.org>,
        Laurent <laurent@augias.org>, linux-kernel@vger.kernel.org
Subject: Re: read_proc issue
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On Wed, Feb 27, 2002 at 09:42:04PM +0000, Alan Cox wrote:
> > I've encountered this problem before, too.  What is the "One True Way"
> > to do this cleanly?  In other words, if you want to do a calculation
> > once every time someone runs "cat /proc/foo", what is the cleanest way
> > to do that?  The solution we came up with was to check the file offset
> > and only do the calculation if offset == 0, which seems pretty
> > hackish.
> 
> Another approach is to do the calculation open and remember it in per
> fd private data. You can recover that and free it on release. It could
> even be a buffer holding the actual "content"

It might also be an idea to export proc_calc_metrics() from
fs/proc/proc_misc.c because quite a lot of code actually tries to do
exactly the same.


Erik

-- 
J.A.K. (Erik) Mouw, Information and Communication Theory Group, Faculty
of Information Technology and Systems, Delft University of Technology,
PO BOX 5031, 2600 GA Delft, The Netherlands  Phone: +31-15-2783635
Fax: +31-15-2781843  Email: J.A.K.Mouw@its.tudelft.nl
WWW: http://www-ict.its.tudelft.nl/~erik/
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