From owner-freebsd-net@FreeBSD.ORG  Wed May 29 18:16:46 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])
 by hub.freebsd.org (Postfix) with ESMTP id CC04CAB6;
 Wed, 29 May 2013 18:16:46 +0000 (UTC) (envelope-from jhb@freebsd.org)
Received: from bigwig.baldwin.cx (bigwig.baldwin.cx [IPv6:2001:470:1f11:75::1])
 by mx1.freebsd.org (Postfix) with ESMTP id A96C8E5C;
 Wed, 29 May 2013 18:16:46 +0000 (UTC)
Received: from jhbbsd.localnet (unknown [209.249.190.124])
 by bigwig.baldwin.cx (Postfix) with ESMTPSA id 298E4B993;
 Wed, 29 May 2013 14:16:46 -0400 (EDT)
From: John Baldwin <jhb@freebsd.org>
To: freebsd-net@freebsd.org
Subject: Re: RFC: removing redundant checks in ether_input_internal()
Date: Wed, 29 May 2013 13:16:39 -0400
User-Agent: KMail/1.13.5 (FreeBSD/8.2-CBSD-20110714-p25; KDE/4.5.5; amd64; ; )
References: <20130522125828.GA93728@onelab2.iet.unipi.it>
 <519CDBE9.304@freebsd.org>
In-Reply-To: <519CDBE9.304@freebsd.org>
MIME-Version: 1.0
Content-Type: Text/Plain;
  charset="iso-8859-1"
Content-Transfer-Encoding: 7bit
Message-Id: <201305291316.39654.jhb@freebsd.org>
X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.2.7
 (bigwig.baldwin.cx); Wed, 29 May 2013 14:16:46 -0400 (EDT)
Cc: Luigi Rizzo <rizzo@iet.unipi.it>, Andre Oppermann <andre@freebsd.org>,
 net@freebsd.org
X-BeenThere: freebsd-net@freebsd.org
X-Mailman-Version: 2.1.14
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: Wed, 29 May 2013 18:16:46 -0000

On Wednesday, May 22, 2013 10:53:29 am Andre Oppermann wrote:
> On 22.05.2013 14:58, Luigi Rizzo wrote:
> > if_ethersubr.c :: ether_input_internal() is only called as follows:
> >
> >      static void
> >      ether_nh_input(struct mbuf *m)
> >      {
> >
> >          ether_input_internal(m->m_pkthdr.rcvif, m);
> >      }
> >
> > hence the following checks in the body are unnecessary:
> >
> >          if (m->m_pkthdr.rcvif == NULL) {
> >                  if_printf(ifp, "discard frame w/o interface pointer\n");
> >                  ifp->if_ierrors++;
> >                  m_freem(m);
> >                  return;
> >          }
> >      #ifdef DIAGNOSTIC
> >          if (m->m_pkthdr.rcvif != ifp) {
> >                  if_printf(ifp, "Warning, frame marked as received on 
%s\n",
> >                          m->m_pkthdr.rcvif->if_xname);
> >          }
> >      #endif
> >
> > Any objection if i remove them ?
> 
> No, but they should remain as KASSERTs.  None of these should trigger in
> production and all of them are an indication that something is very wrong
> with the packet or the caller.

Eh, but if the only caller is ether_nh_input() then by definition you know
that m->m_pkthdr.rcvif == ifp.

-- 
John Baldwin