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To: Andrew Morton <akpm@digeo.com>
Cc: bzzz@tmi.comex.ru, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] remove BKL from ext2's readdir
From: Andi Kleen <ak@muc.de>
Date: Sat, 15 Mar 2003 22:55:11 +0100
In-Reply-To: <20030315023614.3e28e67b.akpm@digeo.com.suse.lists.linux.kernel> (Andrew
 Morton's message of "15 Mar 2003 11:38:42 +0100")
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Andrew Morton <akpm@digeo.com> writes:

> foo_readdir()
> {
> 	loff_t pos = file->f_pos;
>
> 	....
> 	<code which doesn't touch file->f_pos, but which modifies pos>
> 	...
>
> 	file->f_pos = pos;
> }

At least for alpha this will require an rmb_depends() between the read
and the write. Probably on x86 an rmb() wouldn't hurt neither.

Otherwise there is no guarantee other CPUs see that intended memory 
modification order

-Andi
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