From mboxrd@z Thu Jan 1 00:00:00 1970 From: Frank Blaschka Subject: Re: [patch 2/2] [PATCH] qeth: l3 hw tx csum circumvent hw bug Date: Thu, 13 Jan 2011 09:23:59 +0100 Message-ID: <20110113082359.GA11455@tuxmaker.boeblingen.de.ibm.com> References: <20110113064223.429450048@de.ibm.com> <20110113064310.729751199@de.ibm.com> <20110112.234735.160088590.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: netdev@vger.kernel.org, linux-s390@vger.kernel.org To: David Miller Return-path: Received: from mtagate7.uk.ibm.com ([194.196.100.167]:33666 "EHLO mtagate7.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753171Ab1AMIYC (ORCPT ); Thu, 13 Jan 2011 03:24:02 -0500 Content-Disposition: inline In-Reply-To: <20110112.234735.160088590.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, Jan 12, 2011 at 11:47:35PM -0800, David Miller wrote: > From: frank.blaschka@de.ibm.com > Date: Thu, 13 Jan 2011 07:42:25 +0100 > > > --- a/drivers/s390/net/qeth_l3_main.c > > +++ b/drivers/s390/net/qeth_l3_main.c > > @@ -2998,7 +2998,9 @@ static inline void qeth_l3_hdr_csum(stru > > */ > > if (iph->protocol == IPPROTO_UDP) > > hdr->hdr.l3.ext_flags |= QETH_HDR_EXT_UDP; > > - hdr->hdr.l3.ext_flags |= QETH_HDR_EXT_CSUM_TRANSP_REQ; > > + hdr->hdr.l3.ext_flags |= QETH_HDR_EXT_CSUM_TRANSP_REQ | > > + QETH_HDR_EXT_CSUM_HDR_REQ; > > + iph->check = 0; > > if (card->options.performance_stats) > > card->perf_stats.tx_csum++; > > } > > You may not change the packet header contents blindly like this. > Otherwise unpredictable contents will be seen by tcpdump and any > other code path which has a clone of this packet. > > Thus, you'll need to guard this change with something like: > > if (skb_header_cloned(skb) && > pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) { > dev_kfree_skb(skb); > goto tx_fail; > } Yes I know. Because of the suboptimal l3 driver design :-) we already have a private copy of the skb at this place. Thx! > > Please fix this and resubmit your two patches. > -- > 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