From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael Chan" Subject: RE: [PATCH v2 net 2/2] tg3: Fix data corruption on 5725 with TSO Date: Wed, 15 May 2013 08:12:34 -0700 Message-ID: <1368630754.3768.14.camel@LTIRV-MCHAN1.corp.ad.broadcom.com> References: <1368479056-11780-1-git-send-email-nsujir@broadcom.com> <1368479056-11780-3-git-send-email-nsujir@broadcom.com> <1368479644.13473.121.camel@edumazet-glaptop> <51915C7D.2000407@broadcom.com> <1368481224.13473.124.camel@edumazet-glaptop> <51915F77.5000405@broadcom.com> <1368543869.12268.49.camel@LTIRV-MCHAN1.corp.ad.broadcom.com> <1368548345.12268.76.camel@LTIRV-MCHAN1.corp.ad.broadcom.com> Mime-Version: 1.0 Content-Type: text/plain; charset=cp1252 Content-Transfer-Encoding: 7bit Cc: "Nithin Nayak Sujir" , "Eric Dumazet" , davem@davemloft.net, netdev@vger.kernel.org, stable@vger.kernel.org To: "David Laight" Return-path: Received: from mms2.broadcom.com ([216.31.210.18]:1659 "EHLO mms2.broadcom.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756602Ab3EOPMn (ORCPT ); Wed, 15 May 2013 11:12:43 -0400 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On Wed, 2013-05-15 at 09:56 +0100, David Laight wrote: > > > If the 'fix' is to relocate the skb you are doomed to lose regardless > > > of the check - unless you are willing to reallocate a lot of times, > > > and without freeing the old skb. > > > I'd assumed the 'fix' was to disable the relevant offload. > > > > We relocate once and then drop the packet if we encounter additional > > errors, including OOM, DMA mapping error, 4G boundary, etc. The new > > linear skb should not hit the 4G boundary again. The room between the > > end of this current buffer and 4G isn't big enough for the new linear > > skb. > > The first skb might be just below the 4G boundary and the > second just below the 8G one. > We will discard the packet if that happens. I think the probabilty is very small.