From owner-freebsd-current@FreeBSD.ORG  Thu Aug 22 00:30:06 2013
Return-Path: <owner-freebsd-current@FreeBSD.ORG>
Delivered-To: current@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org
 [IPv6:2001:1900:2254:206a::19:1])
 (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits))
 (No client certificate requested)
 by hub.freebsd.org (Postfix) with ESMTP id 85119F34;
 Thu, 22 Aug 2013 00:30:06 +0000 (UTC) (envelope-from yuri@rawbw.com)
Received: from shell0.rawbw.com (shell0.rawbw.com [198.144.192.45])
 by mx1.freebsd.org (Postfix) with ESMTP id 6AE36297C;
 Thu, 22 Aug 2013 00:30:06 +0000 (UTC)
Received: from eagle.yuri.org (stunnel@localhost [127.0.0.1])
 (authenticated bits=0)
 by shell0.rawbw.com (8.14.4/8.14.4) with ESMTP id r7M0U6VU088201;
 Wed, 21 Aug 2013 17:30:06 -0700 (PDT) (envelope-from yuri@rawbw.com)
Message-ID: <52155B8D.1020807@rawbw.com>
Date: Wed, 21 Aug 2013 17:30:05 -0700
From: Yuri <yuri@rawbw.com>
User-Agent: Mozilla/5.0 (X11; FreeBSD amd64;
 rv:17.0) Gecko/20130628 Thunderbird/17.0.7
MIME-Version: 1.0
To: Mateusz Guzik <mjguzik@gmail.com>
Subject: Re: How to best overload the fileops ?
References: <521508F4.6030502@rawbw.com> <20130821232113.GD94127@funkthat.com>
 <521552E2.2000008@rawbw.com> <20130822001022.GA18115@dft-labs.eu>
In-Reply-To: <20130822001022.GA18115@dft-labs.eu>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Cc: John-Mark Gurney <jmg@funkthat.com>, Roman Divacky <rdivacky@freebsd.org>,
 current@freebsd.org
X-BeenThere: freebsd-current@freebsd.org
X-Mailman-Version: 2.1.14
Precedence: list
List-Id: Discussions about the use of FreeBSD-current
 <freebsd-current.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/options/freebsd-current>, 
 <mailto:freebsd-current-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-current>
List-Post: <mailto:freebsd-current@freebsd.org>
List-Help: <mailto:freebsd-current-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-current>,
 <mailto:freebsd-current-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Thu, 22 Aug 2013 00:30:06 -0000

On 08/21/2013 17:10, Mateusz Guzik wrote:
> Short answer is provide epollops with your own fo_close and the rest as
> it is currently in kqueueops. All function are static, but this is not a
> real problem since you have to modify kern_event.c anyway.

This is exactly what this code I am asking about is doing.
kqueueops functions are all static. This modification allows to export 
fileops to child modules.
Since there is nothing similar in the kernel code, I am asking does this 
way look ugly or not.

>
> I don't know how your code looks like in general, so in case its not
> clear, simply wrapping sys_kqueue is inherently racy (some other thread
> may close the fd or even reuse it for something else by the time you try
> to do anything with it), thus modification of current code is
> unavoidable.

No, sys_kqueue calling code is all protected by the lock on this file 
object. So nobody can close or reuse it.

Yuri