From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian Campbell Subject: Re: [PATCH] xen: netfront: Drop GSO SKBs which do not have csum_blank. Date: Sat, 22 Jan 2011 09:43:12 +0000 Message-ID: <1295689392.3693.153.camel@localhost.localdomain> References: <1294233811-28123-1-git-send-email-ian.campbell@citrix.com> <4D3A2BD2.5030802@goop.org> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Cc: "netdev@vger.kernel.org" , "xen-devel@lists.xensource.com" To: Jeremy Fitzhardinge Return-path: Received: from smtp02.citrix.com ([66.165.176.63]:62891 "EHLO SMTP02.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751883Ab1AVJnV (ORCPT ); Sat, 22 Jan 2011 04:43:21 -0500 In-Reply-To: <4D3A2BD2.5030802@goop.org> Sender: netdev-owner@vger.kernel.org List-ID: On Sat, 2011-01-22 at 00:58 +0000, Jeremy Fitzhardinge wrote: > On 01/05/2011 05:23 AM, Ian Campbell wrote: > > The Linux network stack expects all GSO SKBs to have ip_summed == > > CHECKSUM_PARTIAL (which implies that the frame contains a partial > > checksum) and the Xen network ring protocol similarly expects an SKB > > which has GSO set to also have NETRX_csum_blank (which also implies a > > partial checksum). Therefore drop such frames on receive otherwise > > they will trigger the warning in skb_gso_segment. > > > > Signed-off-by: Ian Campbell > > Cc: Jeremy Fitzhardinge > > Cc: xen-devel@lists.xensource.com > > Cc: netdev@vger.kernel.org > > --- > > drivers/net/xen-netfront.c | 5 +++++ > > 1 files changed, 5 insertions(+), 0 deletions(-) > > > > diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c > > index cdbeec9..8b8c480 100644 > > --- a/drivers/net/xen-netfront.c > > +++ b/drivers/net/xen-netfront.c > > @@ -836,6 +836,11 @@ static int handle_incoming_queue(struct net_device *dev, > > dev->stats.rx_errors++; > > continue; > > } > > + } else if (skb_is_gso(skb)) { > > + kfree_skb(skb); > > + packets_dropped++; > > + dev->stats.rx_errors++; > > + continue; > > This looks redundant; why not something like: > > diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c > index 47e6a71..c1b8f64 100644 > --- a/drivers/net/xen-netfront.c > +++ b/drivers/net/xen-netfront.c > @@ -852,13 +852,12 @@ static int handle_incoming_queue(struct net_device *dev, > /* Ethernet work: Delayed to here as it peeks the header. */ > skb->protocol = eth_type_trans(skb, dev); > > - if (skb->ip_summed == CHECKSUM_PARTIAL) { > - if (skb_checksum_setup(skb)) { > - kfree_skb(skb); > - packets_dropped++; > - dev->stats.rx_errors++; > - continue; > - } > + if (skb->ip_summed != CHECKSUM_PARTIAL || > + skb_checksum_setup(skb)) { That drops non-partial skbs. However they are fine unless they also claim to be gso. Perhaps you meant "skb->ip_summed == CHECKSUM_PARTIAL && ! skb_checksum_setup(skb)" which I think works but doesn't allow us to correctly chain the gso check onto the else. Ian. > + kfree_skb(skb); > + packets_dropped++; > + dev->stats.rx_errors++; > + continue; > } > > dev->stats.rx_packets++; > > Thanks, > J > >