From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from [140.186.70.92] (port=37423 helo=eggs.gnu.org)
	by lists.gnu.org with esmtp (Exim 4.43) id 1OnV9i-0006mQ-Eo
	for qemu-devel@nongnu.org; Mon, 23 Aug 2010 07:25:35 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69)
	(envelope-from <paolo.bonzini@gmail.com>) id 1OnV9f-0005a6-FK
	for qemu-devel@nongnu.org; Mon, 23 Aug 2010 07:25:32 -0400
Received: from mail-vw0-f45.google.com ([209.85.212.45]:41507)
	by eggs.gnu.org with esmtp (Exim 4.69)
	(envelope-from <paolo.bonzini@gmail.com>) id 1OnV9f-0005Zy-Bi
	for qemu-devel@nongnu.org; Mon, 23 Aug 2010 07:25:31 -0400
Received: by vws19 with SMTP id 19so5276348vws.4
	for <qemu-devel@nongnu.org>; Mon, 23 Aug 2010 04:25:30 -0700 (PDT)
Sender: Paolo Bonzini <paolo.bonzini@gmail.com>
Message-ID: <4C725AA4.2020905@redhat.com>
Date: Mon, 23 Aug 2010 13:25:24 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
MIME-Version: 1.0
References: <20100803161914.15514.59304.stgit@localhost6.localdomain6>	<m38w41psje.fsf@blackfin.pond.sub.org>	<1282308092.3860.0.camel@x201>	<m3tymp9tgp.fsf@blackfin.pond.sub.org>	<4C6EA5C9.8080700@codemonkey.ws>	<m3vd756z38.fsf@blackfin.pond.sub.org>
	<4C6EC5AA.6050502@codemonkey.ws>
In-Reply-To: <4C6EC5AA.6050502@codemonkey.ws>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Subject: [Qemu-devel] Re: [PATCH] qdev: Reset hotplugged devices
List-Id: qemu-devel.nongnu.org
List-Unsubscribe: <http://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <http://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Anthony Liguori <anthony@codemonkey.ws>
Cc: Alex Williamson <alex.williamson@redhat.com>, glommer@redhat.com, Markus Armbruster <armbru@redhat.com>, qemu-devel@nongnu.org

On 08/20/2010 08:12 PM, Anthony Liguori wrote:
> +/* Returns false to terminate walk; true to continue */
> +typedef int (qdev_walkerfn)(DeviceState *dev, void *opaque);
> +

Since you're introducing qbus_walk_children, I suggest a different 
interface: qdev_walkerfn should return 0 to walk children, -1 to skip 
walking children, and anything else to terminate walk.  If anything ever 
returns x > 0, qbus_walk_children returns that x, else 
qbus_walk_children returns 0.  This interface is inspired by a similar 
one in GCC and it works well.

If you don't want to introduce the full complication, removing the "-1 
to skip walking children" part would still give the same flexibility WRT 
to the return values, which is the important part.

Paolo