netdev - Re: "ADDRCONF(NETDEV_UP): eth0: link is not ready" with IPv6

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Date:	Fri, 29 Jun 2012 16:24:33 +0100
From:	Ben Hutchings <bhutchings@...arflare.com>
To:	Arvid Brodin <Arvid.Brodin@...n.com>
CC:	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	Alexey Kuznetsov <kuznet@....inr.ac.ru>,
	Stephen Hemminger <shemminger@...tta.com>
Subject: Re: "ADDRCONF(NETDEV_UP): eth0: link is not ready" with IPv6

On Fri, 2012-06-29 at 02:36 +0000, Arvid Brodin wrote:
> Hi,
> 
> After 'ip link set eth0 up' on an avr32 board (network driver macb), the device ends up in
> operational mode "UNKNOWN":
> 
> # ip link
> 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UNKNOWN qlen 1000
>     link/ether 00:24:74:00:17:9d brd ff:ff:ff:ff:ff:ff
> 
> Unplugging and plugging in the network cable gets the device to mode "UP".
> 
> This is a problem for me because I'm trying to use this device as a "slave" device (for a
> virtual HSR device*) and I need to be able to decide if the slave device is operational or
> not.
> 
> Following Stephen's advice here:
> http://kerneltrap.org/mailarchive/linux-netdev/2008/9/24/3398834 I checked the macb.c code
> and noticed they do not call netif_carrier_off() neither before register_netdev() nor in
> dev_open().

It should be called after register_netdev() and before the driver's
ndo_open implementation returns.

> I added the call before register_netdev(), which fixed the problem. However, if I then
> enable IPv6:
>
> # ip link set eth0 up
> ADDRCONF(NETDEV_UP): eth0: link is not ready
> eth0: link up (100/Full)
> ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready

This looks normal.

> Any idea what is happening / what I'm doing wrong? (This is not just cosmetic; is some
> situations this seems to kill the interface - e.g. ping does not work, down/up does not
> help...) Things work fine without IPv6 configured.

Perhaps some packets sent automatically by IPv6 are triggering a driver
bug?  Or there is a bug in multicast support, which IPv6 always uses.

Ben.

> *N.B. I'm writing a driver for a network protocol called "High-availability Seamless
> Redundancy".

-- 
Ben Hutchings, Staff Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.

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