From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Wong <normalperson@yhbt.net>
Subject: Re: [PATCH] epoll: prevent missed events on EPOLL_CTL_MOD
Date: Wed, 2 Jan 2013 21:16:32 +0000
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Eric Wong <normalperson@yhbt.net> wrote:
> Linus Torvalds <torvalds@linux-foundation.org> wrote:
> > Please document the barrier that this mb() pairs with, and then give
> > an explanation for the fix in the commit message, and I'll happily
> > take it. Even if it's just duplicating the comments above the
> > wq_has_sleeper() function, except modified for the ep_modify() case.
> 
> Hopefully my explanation is correct and makes sense below,
> I think both effects of the barrier are needed

I noticed Linus accepted this already.  This should probably go to
stable, right?

>>From ancient git history[1], it seems this bug exists for all
2.6 kernels:

	commit 424980a87e226d63af46579b2af16ec1b8d17e52
	Author: Davide Libenzi <davidel@xmailserver.org>
	Date:   Thu Nov 14 16:17:23 2002 -0800

	    [PATCH] epoll bits 0.46 ...

[1] - git://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git