From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Guo-Fu Tseng" Subject: Re: jme: UDP checksum error, and lots of them Date: Thu, 2 Dec 2010 12:33:01 +0800 Message-ID: <20101202042820.M98672@cooldavid.org> References: <20101201.200935.71110482.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Cc: netdev@vger.kernel.org To: David Miller , jengelh@medozas.de Return-path: Received: from cooldavid.org ([114.33.45.68]:48560 "EHLO cooldavid.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756804Ab0LBEdL (ORCPT ); Wed, 1 Dec 2010 23:33:11 -0500 In-Reply-To: <20101201.200935.71110482.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, 01 Dec 2010 20:09:35 -0800 (PST), David Miller wrote > From: Jan Engelhardt > Date: Thu, 2 Dec 2010 04:39:34 +0100 (CET) > > > Why does the JME driver care so much about this that it needs to print > > this for every packet? It does not look like it has any offloading > > features. > > Well I'm glad it let us know about the bad checksum which would otherwise > have been unnoticed. > > Please try to pinpoint why the checksum is bad, because it seems that > tcpdump agrees with the driver. Perhaps it's some side effect of how > vpnc uses TUN/TAP, or something like that. > > Seeing the bad checksum even in tcpdump, and then seeing proper replies > going back, that is very suspicious and should be looked into. > -- > To unsubscribe from this list: send the line "unsubscribe netdev" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html Indeed... It is suspicious to reply proper response against the packet with bad checksum. Jan: Would you try to turn off the rx-checksum offloading with ethtool and see how it goes? I suspect that there might be some the HW-Checksum behavior error. ex: Replaced the UDP checksum field while it's all zero(no need to checksum) Guo-Fu Tseng