netdev - [PATCH] net: Fix tentative IPv6 address due to DAD looping back

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Message-ID: <D6EA916C7149064CB4D5C686612478A3183E2D27D1@MX34A.corp.emc.com>
Date:	Thu, 21 Mar 2013 23:20:09 -0400
From:	"Meng, Jilin" <Jilin.Meng@....com>
To:	"davem@...emloft.net" <davem@...emloft.net>,
	"kuznet@....inr.ac.ru" <kuznet@....inr.ac.ru>,
	"jmorris@...ei.org" <jmorris@...ei.org>,
	"yoshfuji@...ux-ipv6.org" <yoshfuji@...ux-ipv6.org>,
	"kaber@...sh.net" <kaber@...sh.net>
CC:	"Sun, Yinglin" <yinglin.sun@....com>,
	"Prithviraj, Lakshmanan" <lakshmanan.prithviraj@....com>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: [PATCH] net: Fix tentative IPv6 address due to DAD looping back

we should ignore the looped-back IPv6 DAD packet to avoid configuration failure.
This occurs when a bonding interface with roundrobin mode is being configured an IPv6 address 
while the switch side isn't configured bonding/channel yet.

Signed-off-by: Jilin Meng <jilin.meng@....com>
Signed-off-by: Yinglin Sun <yinglin.sun@....com>
Signed-off-by: Lakshmanan Prithviraj <lakshmanan.prithviraj@....com>
---
--- linux/net/ipv6/ndisc.c.orig	2013-03-12 17:16:18.000000000 +0800
+++ linux/net/ipv6/ndisc.c	2013-03-21 10:37:06.000000000 +0800
@@ -757,6 +757,24 @@ static void ndisc_recv_ns(struct sk_buff
 
 		if (ifp->flags & (IFA_F_TENTATIVE|IFA_F_OPTIMISTIC)) {
 			if (dad) {
+				if (dev->type == ARPHRD_ETHER) {
+					const unsigned char *sadr;
+					sadr = skb_mac_header(skb);
+					if (sadr[6] == dev->dev_addr[0] &&
+					    sadr[7] == dev->dev_addr[1] &&
+					    sadr[8] == dev->dev_addr[2] &&
+					    sadr[9] == dev->dev_addr[3] &&
+					    sadr[10] == dev->dev_addr[4] &&
+					    sadr[11] == dev->dev_addr[5]) {
+					/*
+					 * looped-back to us. This occurs when
+					 * a bonding interface with roundrobin
+					 * mode is being configured while the
+					 * switch side isn't configured yet.
+					 */
+						goto out;
+				}
+
 				/*
 				 * We are colliding with another node
 				 * who is doing DAD
--
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