From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH v2 net-next 1/2] bpf: make programs see skb->data == L2 for ingress and egress Date: Sun, 07 Jun 2015 02:01:53 -0700 (PDT) Message-ID: <20150607.020153.2078872410885973154.davem@davemloft.net> References: <1433437914-15808-1-git-send-email-ast@plumgrid.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: edumazet@google.com, jhs@mojatatu.com, daniel@iogearbox.net, netdev@vger.kernel.org To: ast@plumgrid.com Return-path: Received: from shards.monkeyblade.net ([149.20.54.216]:39904 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753206AbbFGJBy (ORCPT ); Sun, 7 Jun 2015 05:01:54 -0400 In-Reply-To: <1433437914-15808-1-git-send-email-ast@plumgrid.com> Sender: netdev-owner@vger.kernel.org List-ID: From: Alexei Starovoitov Date: Thu, 4 Jun 2015 10:11:53 -0700 > eBPF programs attached to ingress and egress qdiscs see inconsistent skb->data. > For ingress L2 header is already pulled, whereas for egress it's present. > This is known to program writers which are currently forced to use > BPF_LL_OFF workaround. > Since programs don't change skb internal pointers it is safe to do > pull/push right around invocation of the program and earlier taps and > later pt->func() will not be affected. > Multiple taps via packet_rcv(), tpacket_rcv() are doing the same trick > around run_filter/BPF_PROG_RUN even if skb_shared. > > This fix finally allows programs to use optimized LD_ABS/IND instructions > without BPF_LL_OFF for higher performance. > tc ingress + cls_bpf + samples/bpf/tcbpf1_kern.o > w/o JIT w/JIT > before 20.5 23.6 Mpps > after 21.8 26.6 Mpps > > Old programs with BPF_LL_OFF will still work as-is. > > We can now undo most of the earlier workaround commit: > a166151cbe33 ("bpf: fix bpf helpers to use skb->mac_header relative offsets") > > Signed-off-by: Alexei Starovoitov Applied.