From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [patch] eventfd - revised interface and cleanups (2nd rev)
Date: Tue, 23 Jun 2009 14:25:11 -0700
Message-ID: <20090623142511.c9068655.akpm@linux-foundation.org>
References: <alpine.DEB.1.10.0906230936280.17001@makko.or.mcafeemobile.com>
	<alpine.DEB.1.10.0906231219450.17001@makko.or.mcafeemobile.com>
	<20090623131239.711d9f83.akpm@linux-foundation.org>
	<alpine.DEB.1.10.0906231355130.17001@makko.or.mcafeemobile.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Cc: linux-kernel@vger.kernel.org, avi@redhat.com, kvm@vger.kernel.org,
	ghaskins@novell.com, rusty@rustcorp.com.au, bcrl@kvack.org
To: Davide Libenzi <davidel@xmailserver.org>
Return-path: <kvm-owner@vger.kernel.org>
Received: from smtp1.linux-foundation.org ([140.211.169.13]:57359 "EHLO
	smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK)
	by vger.kernel.org with ESMTP id S1754517AbZFWV0L (ORCPT
	<rfc822;kvm@vger.kernel.org>); Tue, 23 Jun 2009 17:26:11 -0400
In-Reply-To: <alpine.DEB.1.10.0906231355130.17001@makko.or.mcafeemobile.com>
Sender: kvm-owner@vger.kernel.org
List-ID: <kvm.vger.kernel.org>

On Tue, 23 Jun 2009 13:59:07 -0700 (PDT)
Davide Libenzi <davidel@xmailserver.org> wrote:

> On Tue, 23 Jun 2009, Andrew Morton wrote:
> 
> > On Tue, 23 Jun 2009 12:25:36 -0700 (PDT)
> > Davide Libenzi <davidel@xmailserver.org> wrote:
> > 
> > > Another cleanup this patch does, is making AIO select EVENTFD, instead of 
> > > adding a bunch of empty function stubs inside eventfd.h in order to 
> > > handle the (AIO && !EVENTFD) case.
> > 
> > Given that we're trying to squeak this patch into 2.6.31, it's quite
> > unfortunate to include unrelated changes.  Especially ones which
> > involve the always-problematic "select".  Although this one looks less
> > than usually deadly due to the simple dependencies of AIO and eventfd.
> > 
> > However...
> > 
> > Is this a good way of fixing the (AIO && !EVENTFD) case?  Surely if the
> > developer selected this combination, he doesn't want to carry the
> > overhead of including eventfd.  IOW, if AIO can work acceptably without
> > eventfd being compiled into the kernel then adding the stubs is a
> > superior solution.
> 
> IMO when someone says "AIO included in the kernel", should get the whole 
> AIO functionality and not part of it.
> People already started using KAIO+eventfd, and a (AIO && !EVENTFD) config 
> will make their code fail.

That isn't for us to decide. Entire syscalls can be disabled in config.