From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH 01/10] net: sctp: fix checksum marking for outgoing packets Date: Thu, 14 Jul 2011 14:37:10 -0700 (PDT) Message-ID: <20110714.143710.1285450081984113368.davem@davemloft.net> References: Mime-Version: 1.0 Content-Type: Text/Plain; charset=euc-kr Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: netdev@vger.kernel.org, vladislav.yasevich@hp.com, sri@us.ibm.com, linux-sctp@vger.kernel.org To: mirq-linux@rere.qmqm.pl Return-path: Received: from shards.monkeyblade.net ([198.137.202.13]:60319 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932232Ab1GNViR (ORCPT ); Thu, 14 Jul 2011 17:38:17 -0400 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: =46rom: Micha=A9=A9 Miros=A9=A9aw Date: Thu, 14 Jul 2011 02:10:29 +0200 (CEST) > Packets to devices without NETIF_F_SCTP_CSUM (including NETIF_F_NO_CS= UM) > should be properly checksummed because the packets can be diverted or > rerouted after construction. This still leaves packets diverted from > NETIF_F_SCTP_CSUM-enabled devices with broken checksums. Fixing this > needs implementing software offload fallback in networking core. >=20 > For users of sctp_checksum_disable, skb->ip_summed should be left as > CHECKSUM_NONE and not CHECKSUM_UNNECESSARY as per include/linux/skbuf= f.h. >=20 > Signed-off-by: Micha=A9=A9 Miros=A9=A9aw This is not the way to fix this. We need to add the proper software fallback when the SKB device changes to one with SCTP/NO_CSUM to one that does not.