Subject: Re: [PATCH net-next v4] ipvlan: Initial check-in of the IPVLAN driver.

From: Toshiaki Makita <[email-masked]>
Date: Thu, 27 Nov 2014 10:59:58 +0900

On 2014/11/27 2:05, Mahesh Bandewar wrote:
> On Tue, Nov 25, 2014 at 10:41 PM, Toshiaki Makita
> <[email-masked]> wrote:
>> Hi Mahesh,
>>
>> I found that deleting the last ipvlan device triggers WARN_ON() in
>> rtmsg_ifinfo().
>> ipvlan_nl_fillinfo() seems to return -EINVAL in that case.
>>
>>> +static int ipvlan_nl_fillinfo(struct sk_buff *skb,
>>> +                           const struct net_device *dev)
>>> +{
>>> +     struct ipvl_dev *ipvlan = netdev_priv(dev);
>>> +     struct ipvl_port *port = ipvlan_port_get_rtnl(ipvlan->phy_dev);
>>> +     int ret = -EINVAL;
>>> +
>>> +     if (!port)
>>> +             goto err;
>>> +
>>> +     ret = -EMSGSIZE;
>>> +     if (nla_put_u16(skb, IFLA_IPVLAN_MODE, port->mode))
>>> +             goto err;
>>> +
>>> +     return 0;
>>> +
>>> +err:
>>> +     return ret;
>>> +}
>>
>> rollback_registered_many() calls rtmsg_ifinfo() after calling ndo_uninit().
>> ndo_uninit() (ipvlan_uninit() -> ipvlan_port_destroy() ->
>> netdev_rx_handler_unregister()) sets rx_handler_data into NULL.
>> So, we cannot dereference "port" in ipvlan_nl_fillinfo().
>>
> Calling fillinfo() after calling uninit() seems pointless on any
> device. 

bonding needs calling rtmsg_ifinfo() after calling ndo_uninit().
56bfa7ee7c88 ("unregister_netdevice : move RTM_DELLINK to until after
ndo_uninit")

> But how are you hitting this case? Can you share the command
> sequence with me?

# ip link add link eth0 name ipvl0 type ipvlan
# ip link del ipvl0

Thanks,
Toshiaki Makita

> 
> Thanks,
> --mahesh..
> 
>> Maybe "mode" should belong to struct ipvl_dev?
>>
>> Thanks,
>> Toshiaki Makita