From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH v3 net-next RFC] Generic XDP Date: Wed, 12 Apr 2017 22:08:28 -0400 (EDT) Message-ID: <20170412.220828.661268690055956936.davem@davemloft.net> References: <20170412.145415.1441440342830198148.davem@davemloft.net> <0861d2c9-a5ec-f40e-b849-f6421938b357@cumulusnetworks.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, xdp-newbies@vger.kernel.org To: dsa@cumulusnetworks.com Return-path: Received: from shards.monkeyblade.net ([184.105.139.130]:53176 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755271AbdDMCIa (ORCPT ); Wed, 12 Apr 2017 22:08:30 -0400 In-Reply-To: <0861d2c9-a5ec-f40e-b849-f6421938b357@cumulusnetworks.com> Sender: netdev-owner@vger.kernel.org List-ID: From: David Ahern Date: Wed, 12 Apr 2017 13:54:20 -0600 > packet passed to xdp seems to be messed up Ok, the problem is that skb->mac_len isn't set properly at this point. That doesn't happen until __netif_receive_skb_core(). I'm also not setting xdp.data_hard_start properly. It should work better with this small diff: diff --git a/net/core/dev.c b/net/core/dev.c index 9ed4569..d36ae8f 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -4289,6 +4289,7 @@ static u32 netif_receive_generic_xdp(struct sk_buff *skb, u32 act = XDP_DROP; void *orig_data; int hlen, off; + u32 mac_len; if (skb_linearize(skb)) goto do_drop; @@ -4296,10 +4297,11 @@ static u32 netif_receive_generic_xdp(struct sk_buff *skb, /* The XDP program wants to see the packet starting at the MAC * header. */ - hlen = skb_headlen(skb) + skb->mac_len; - xdp.data = skb->data - skb->mac_len; + mac_len = skb->data - skb_mac_header(skb); + hlen = skb_headlen(skb) + mac_len; + xdp.data = skb->data - mac_len; xdp.data_end = xdp.data + hlen; - xdp.data_hard_start = xdp.data - skb_headroom(skb); + xdp.data_hard_start = skb->data - skb_headroom(skb); orig_data = xdp.data; act = bpf_prog_run_xdp(xdp_prog, &xdp);