From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jiri Pirko Subject: Re: [patch net-next-2.6] net: vlan: make non-hw-accel rx path similar to hw-accel Date: Mon, 4 Apr 2011 22:30:02 +0200 Message-ID: <20110404203002.GB3657@psychotron.redhat.com> References: <1301739966-7604-1-git-send-email-jpirko@redhat.com> <4D989100.1090207@gmail.com> <4D996B30.3080408@gmail.com> <20110404071453.GA2791@psychotron.redhat.com> <4D9A1530.1010102@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Jesse Gross , netdev@vger.kernel.org, davem@davemloft.net, shemminger@linux-foundation.org, kaber@trash.net, fubar@us.ibm.com, eric.dumazet@gmail.com, andy@greyhouse.net, xiaosuo@gmail.com, "Eric W. Biederman" To: Nicolas de =?iso-8859-1?Q?Peslo=FCan?= Return-path: Received: from mx1.redhat.com ([209.132.183.28]:1927 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755450Ab1DDUap (ORCPT ); Mon, 4 Apr 2011 16:30:45 -0400 Content-Disposition: inline In-Reply-To: <4D9A1530.1010102@gmail.com> Sender: netdev-owner@vger.kernel.org List-ID: Mon, Apr 04, 2011 at 09:00:00PM CEST, nicolas.2p.debian@gmail.com wrote= : >Le 04/04/2011 09:14, Jiri Pirko a =E9crit : >>Mon, Apr 04, 2011 at 08:54:40AM CEST, nicolas.2p.debian@gmail.com wro= te: >>>Le 03/04/2011 22:38, Jesse Gross a =E9crit : > >>>>It would be nice to merge all of this together. One complication i= s >>>>the interaction of bridging and vlan on the same device. Some peop= le >>>>want to have a bridge for each vlan and a bridge for untagged packe= ts. >>>> On older kernels with vlan accelerated hardware this was possible >>>>because vlan devices would get packets before bridging and on curre= nt >>>>kernels it is possible with ebtables rules. If we use rx_handler f= or >>>>both I believe we would need to extend it some to allow multiple >>>>handlers. >>> >>>I totally agree. >> >>I do not. The reason I do vlan_untag early is so actually emulates >>hw acceleration. The reason is to make rx path of hwaccel an >>nonhwaccel similar. If you move vlan untag to rx_handler, this goal >>wouldn't be achieved. > >Need to think more about that point. > >>>Remember that Jiri's original proposal (last summer) was to have >>>several rx_handlers per net_device. I still think we need several of >>>them, because the network stack need to be generic and allow for any >>>complex stacking setup. The rx_handler framework may need to be >>>enhanced for that, but I think it is the right tool to do all those >>>per net_device specific features. >>> >>>>>This would also cause protocol handlers to receive the untouched (= tagged) >>>>>frame, if no setup required the frame to be untagged, which I thin= k is the >>>>>right thing to do. >>>> >>>>At the very least we need to make sure that these packets are marke= d >>>>as PACKET_OTHERHOST because protocol handlers don't pay attention t= o >>>>the vlan field. >>> >>>Agreed. >>> >>>>>>@@ -3177,7 +3183,7 @@ ncls: >>>>>> ret =3D deliver_skb(skb, pt_prev, orig_dev= ); >>>>>> pt_prev =3D NULL; >>>>>> } >>>>>>- if (vlan_hwaccel_do_receive(&skb)) { >>>>>>+ if (vlan_do_receive(&skb)) { >>>>>> ret =3D __netif_receive_skb(skb); >>>>>> goto out; >>>>>> } else if (unlikely(!skb)) >>>>> >>>>>Why are you calling __netif_receive_skb here? Can't we simply goto >>>>>another_round? >>>> >>>>This code (other than the name change) predates the >>>>another_round/rx_handler changes. >>> >>>Yes, you are right. Let's keep this for a possible follow-up patch, >>>to avoid skb reinjection when it is not strictly necessary. >> >>To do another round here was my attention do do in follow up patch (I= 'm >>still figuring out how to move this effectively into rx_handlers) > >So you want to move vlan_do_receive into an rx_handler, but want >untagging to stay hard-coded at the beginning of __netif_receive_skb. >I don't think I understand the rational behind that. vlan_hwaccel_do_receive/vlan_do_receive could be converted to rx_handler, not untagging.