From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lance Richardson Subject: Re: [PATCH net v3] ipv4: allow local fragmentation in ip_finish_output_gso() Date: Fri, 4 Nov 2016 09:48:02 -0400 (EDT) Message-ID: <1292666010.97911366.1478267282598.JavaMail.zimbra@redhat.com> References: <1478118977-19608-1-git-send-email-lrichard@redhat.com> <20161103094239.13ac8ac2@pixies> <274982955.93728733.1478178387534.JavaMail.zimbra@redhat.com> <20161104112409.6277b7b0@halley> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, fw@strlen.de, jtluka@redhat.com, hannes@stressinduktion.org To: Shmulik Ladkani Return-path: Received: from mx3-phx2.redhat.com ([209.132.183.24]:36458 "EHLO mx3-phx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934360AbcKDNsP (ORCPT ); Fri, 4 Nov 2016 09:48:15 -0400 In-Reply-To: <20161104112409.6277b7b0@halley> Sender: netdev-owner@vger.kernel.org List-ID: > From: "Shmulik Ladkani" > To: "Lance Richardson" > Cc: netdev@vger.kernel.org, fw@strlen.de, jtluka@redhat.com, hannes@stressinduktion.org > Sent: Friday, November 4, 2016 5:24:09 AM > Subject: Re: [PATCH net v3] ipv4: allow local fragmentation in ip_finish_output_gso() > > Hi, > > On Thu, 3 Nov 2016 09:06:27 -0400 (EDT) Lance Richardson > wrote: > > I'm not sure what could be added that would help, was there something > > specific you had in mind? > > How about something like this (preliminary, feel free to massage): > > @@ -248,10 +248,16 @@ static int ip_finish_output_gso(struct net *net, struct > sock *sk, > > /* Slowpath - GSO segment length is exceeding the dst MTU. > * > - * This can happen in two cases: > - * 1) TCP GRO packet, DF bit not set > - * 2) skb arrived via virtio-net, we thus get TSO/GSO skbs directly > - * from host network stack. > + * This can happen in several cases: > + * - Forwarding of TCP GRO packet, DF bit not set > + * - Forwarding of skb arrived in a virtualization environment (from > + * virtio-net/vhost/tap) with TSO/GSO size set by other's network > + * stack > + * - Local GSO skb xmitted on an NETIF_F_TSO tunnel stacked over an > + * interface with a smaller mtu > + * - Arriving GRO skb (or GSO skb in a virtualized env) that gets L2 > + * bridged to a NETIF_F_TSO tunnel stacked over an interface with an > + * insufficent mtu > */ > features = netif_skb_features(skb); > BUILD_BUG_ON(sizeof(*IPCB(skb)) > SKB_SGO_CB_OFFSET); > Thanks, that looks good to me. I can send a follow-up patch with this change, if you like (there seems to be agreement that the original patch is OK). Lance