From owner-freebsd-arch@FreeBSD.ORG  Mon Oct  3 16:44:55 2005
Return-Path: <owner-freebsd-arch@FreeBSD.ORG>
X-Original-To: arch@FreeBSD.org
Delivered-To: freebsd-arch@FreeBSD.ORG
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP id 919DE16A41F;
	Mon,  3 Oct 2005 16:44:55 +0000 (GMT) (envelope-from jhb@FreeBSD.org)
Received: from mv.twc.weather.com (mv.twc.weather.com [65.212.71.225])
	by mx1.FreeBSD.org (Postfix) with ESMTP id EA98743D46;
	Mon,  3 Oct 2005 16:44:54 +0000 (GMT) (envelope-from jhb@FreeBSD.org)
Received: from [10.50.41.233] (Not Verified[10.50.41.233]) by
	mv.twc.weather.com with NetIQ MailMarshal (v6, 0, 3, 8)
	id <B434163cc0000>; Mon, 03 Oct 2005 13:01:00 -0400
From: John Baldwin <jhb@FreeBSD.org>
To: arch@FreeBSD.org
Date: Mon, 3 Oct 2005 12:46:13 -0400
User-Agent: KMail/1.8
MIME-Version: 1.0
Content-Type: text/plain;
  charset="us-ascii"
Content-Transfer-Encoding: 7bit
Content-Disposition: inline
Message-Id: <200510031246.14835.jhb@FreeBSD.org>
Cc: ru@FreeBSD.org, M.@WarnerLosh
Subject: Ethernet driver teardown
X-BeenThere: freebsd-arch@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Discussion related to FreeBSD architecture <freebsd-arch.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-arch>,
	<mailto:freebsd-arch-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-arch>
List-Post: <mailto:freebsd-arch@freebsd.org>
List-Help: <mailto:freebsd-arch-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-arch>,
	<mailto:freebsd-arch-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Mon, 03 Oct 2005 16:44:55 -0000

So, I was thinking about the problem with ethernet driver detach races this 
morning and had an idea.  What if the sequence for detach() was altered such 
that we called ether_ifdetach() before the driver's stop() routine?  Thus, 
you would end up with something like this:

foo_detach()
{

	ether_ifdetach(sc->foo_ifp);
	FOO_LOCK(sc);
	foo_stop(sc);
	FOO_UNLOCK(sc);
	callout_drain(...);
	bus_teardown_intr(...);
	if_free(sc->foo_ifp);
	bus_release_resources(...);
	...
}

Would that solve the various races including letting BPF turn off promiscuous 
mode cleanly without requiring detaching flags in each driver to bail out of 
foo_ioctl()?

-- 
John Baldwin <jhb@FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve"  =  http://www.FreeBSD.org