From owner-freebsd-net@FreeBSD.ORG  Thu Nov 28 20:35:50 2013
Return-Path: <owner-freebsd-net@FreeBSD.ORG>
Delivered-To: freebsd-net@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115])
 (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits))
 (No client certificate requested)
 by hub.freebsd.org (Postfix) with ESMTPS id F2578942
 for <freebsd-net@freebsd.org>; Thu, 28 Nov 2013 20:35:50 +0000 (UTC)
Received: from mail-n.franken.de (drew.ipv6.franken.de
 [IPv6:2001:638:a02:a001:20e:cff:fe4a:feaa])
 (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits))
 (No client certificate requested)
 by mx1.freebsd.org (Postfix) with ESMTPS id B38FA1371
 for <freebsd-net@freebsd.org>; Thu, 28 Nov 2013 20:35:50 +0000 (UTC)
Received: from [192.168.1.102] (p508F1261.dip0.t-ipconnect.de [80.143.18.97])
 (Authenticated sender: macmic)
 by mail-n.franken.de (Postfix) with ESMTP id 71B151C0C0692
 for <freebsd-net@freebsd.org>; Thu, 28 Nov 2013 21:35:47 +0100 (CET)
From: Michael Tuexen <Michael.Tuexen@lurchi.franken.de>
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Subject: ip_output()/if_output() behaviour
Message-Id: <BF7B04F7-0D45-4708-99A8-8BE030109CEC@lurchi.franken.de>
Date: Thu, 28 Nov 2013 21:35:46 +0100
To: "freebsd-net@freebsd.org list" <freebsd-net@freebsd.org>
Mime-Version: 1.0 (Mac OS X Mail 6.6 \(1510\))
X-Mailer: Apple Mail (2.1510)
X-BeenThere: freebsd-net@freebsd.org
X-Mailman-Version: 2.1.16
Precedence: list
List-Id: Networking and TCP/IP with FreeBSD <freebsd-net.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/options/freebsd-net>,
 <mailto:freebsd-net-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-net/>
List-Post: <mailto:freebsd-net@freebsd.org>
List-Help: <mailto:freebsd-net-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-net>,
 <mailto:freebsd-net-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Thu, 28 Nov 2013 20:35:51 -0000

Dear all,

I'm investigating a problem and need to understand the behaviour
of ip_output(). Is it correct that if ip_output() returns an
non-zero error, the corresponding packet was never sent?
In the SCTP stack we assume this, but it seems that at least
the em and the igb driver might return an error from
igb_mq_start_locked(), for example, but have accepted the packet.

Before digging further, I would like to know what the intended
behaviour of ip_output() is.

Thanks in advance
Michael