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

On 07/03/2012 05:47 PM, Arvid Brodin :

(Added MACB "patch" contact Nicolas Ferre to CC list.)

Hi,

(adding linux-arm-kernel)

On 2012-06-29 17:24, Ben Hutchings wrote:

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On Fri, 2012-06-29 at 02:36 +0000, Arvid Brodin wrote:

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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().

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

After having read several drivers, it seems that some are calling
netif_carrier_off() *before* register_netdev() and some *after*... What
is the proper way?

I'm guessing this allows linkwatch to do netif_carrier_on() some time after the dev_open()?

Besides not calling netif_carrier_off() in dev_open(), the Cadence/MACB driver calls
netif_carrier_off() in dev_close(). Is this correct?


How should I handle carrier state for a virtual device? The device should have "carrier"
as long as at least one of the underlying physical interfaces is operational (which I
guess means operational state UP). Would it be correct to watch NETDEV_CHANGE and DOWN/UP
events of the slaves and call netif_carrier_on()/off() on the virtual device depending on
the slaves' states? 

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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.

Good, that narrows it down a bit.

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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.

Sorry, I have no clue on this topic. But I am eager to know if you find
something. I can queue your patch for netif_carrier_off() at least...

Best regards,
-- 
Nicolas Ferre