From mboxrd@z Thu Jan 1 00:00:00 1970 From: Cong Wang Subject: [Patch] openvswitch: fix the calculation of checksum for vlan header Date: Fri, 22 Feb 2013 13:25:22 +0800 Message-ID: <1361510722-27831-1-git-send-email-amwang@redhat.com> Cc: "David S. Miller" , Jesse Gross , Cong Wang To: netdev@vger.kernel.org Return-path: Received: from mx1.redhat.com ([209.132.183.28]:47040 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750790Ab3BVFZs (ORCPT ); Fri, 22 Feb 2013 00:25:48 -0500 Sender: netdev-owner@vger.kernel.org List-ID: From: Cong Wang In vlan_insert_tag(), we insert a 4-byte VLAN header _after_ mac header: memmove(skb->data, skb->data + VLAN_HLEN, 2 * ETH_ALEN); ... veth->h_vlan_proto = htons(ETH_P_8021Q); ... veth->h_vlan_TCI = htons(vlan_tci); so after it, we should recompute the checksum to include these 4 bytes. skb->data still points to the mac header, therefore VLAN header is at (2 * ETH_ALEN = 12) bytes after it, not (ETH_HLEN = 14) bytes. This can also be observed via tcpdump: 0x0000: ffff ffff ffff 5254 005d 6f6e 8100 000a 0x0010: 0806 0001 0800 0604 0001 5254 005d 6f6e 0x0020: c0a8 026e 0000 0000 0000 c0a8 0282 Cc: David S. Miller Cc: Jesse Gross Signed-off-by: Cong Wang --- diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c index ac2defe..a0e202c 100644 --- a/net/openvswitch/actions.c +++ b/net/openvswitch/actions.c @@ -115,7 +115,7 @@ static int push_vlan(struct sk_buff *skb, const struct ovs_action_push_vlan *vla if (skb->ip_summed == CHECKSUM_COMPLETE) skb->csum = csum_add(skb->csum, csum_partial(skb->data - + ETH_HLEN, VLAN_HLEN, 0)); + + (2 * ETH_ALEN), VLAN_HLEN, 0)); } __vlan_hwaccel_put_tag(skb, ntohs(vlan->vlan_tci) & ~VLAN_TAG_PRESENT);