linux-kernel - [PATCH v2 0/2] signalfd/epoll fixes

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Date:	Fri, 24 Feb 2012 20:06:51 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Davide Libenzi <davidel@...ilserver.org>,
	Eric Dumazet <eric.dumazet@...il.com>,
	Greg KH <greg@...ah.com>, Jason Baron <jbaron@...hat.com>,
	Roland McGrath <roland@...k.frob.com>,
	Eugene Teo <eugeneteo@...nel.sg>,
	Maxime Bizon <mbizon@...ebox.fr>,
	Denys Vlasenko <dvlasenk@...hat.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2 0/2] signalfd/epoll fixes

On 02/23, Linus Torvalds wrote:
>
> On Thu, Feb 23, 2012 at 7:44 AM, Oleg Nesterov <oleg@...hat.com> wrote:
> >
> > Or we can rely on the fact that sighand_cachep is SLAB_DESTROY_BY_RCU,
> > and assume that ->whead is always rcu-protected if it can go away.
> >
> > In this case we don't need 3/4 (although it makes sense to add the
> > fat comment), and 4/4 can be simplified, see below.
>
> Ok.
>
> Can you also get rid of 1/4, because quite frankly, adding that
> BUG_ON() is just annoying. Either the thing gets fixed or not, but at
> no point is it ok to say "ok, I'm going to fix it, but before I do
> I'll just make it much worse".

OK. Please see v2.

Other changes:

	- some comments

	- now that we rely on rcu, ep_poll_callback() can do
	  remove_wait_queue() outsife of ep->lock



Davide, I see the new email, but it is too late for me to reply
today. Anyway, I think it makes sense to make the "simple" fix
before anything else. IOW, I'd suggest these changes for now in
any case (unless, of course, you see some problems).

Oleg.

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