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

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Message-ID: <027526AF93736D4380632CD4F3B42B8002FEAD@MX101CL02.corp.emc.com>
Date:	Thu, 11 Apr 2013 03:11:28 +0000
From:	"Meng, Jilin" <Jilin.Meng@....com>
To:	YOSHIFUJI Hideaki <yoshfuji@...ux-ipv6.org>
CC:	"davem@...emloft.net" <davem@...emloft.net>,
	"kuznet@....inr.ac.ru" <kuznet@....inr.ac.ru>,
	"jmorris@...ei.org" <jmorris@...ei.org>,
	"kaber@...sh.net" <kaber@...sh.net>,
	"Sun, Yinglin" <yinglin.sun@....com>,
	"Prithviraj, Lakshmanan" <lakshmanan.prithviraj@....com>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: RE: [PATCH] net: Fix tentative IPv6 address due to DAD looping back

Yoshfuji,

Partially you are correct. 
But at least this fix removes the limitation that we must configure the switch for bonding first then host in this case.

-Jilin

-----Original Message-----
From: YOSHIFUJI Hideaki [mailto:yoshfuji@...ux-ipv6.org] 
Sent: Friday, March 22, 2013 11:40 AM
To: Meng, Jilin
Cc: davem@...emloft.net; kuznet@....inr.ac.ru; jmorris@...ei.org; kaber@...sh.net; Sun, Yinglin; Prithviraj, Lakshmanan; netdev@...r.kernel.org
Subject: Re: [PATCH] net: Fix tentative IPv6 address due to DAD looping back

Meng, Jilin wrote:
> 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

I would say that it is a configuration error.

--yoshfuji


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