Re: getting VF link info seems to be broken in 3.9-rc8

[David Miller <davem@davemloft.net>]

From: Alexander Duyck <alexander.h.duyck@intel.com>
Date: Thu, 25 Apr 2013 13:20:24 -0700

> On 04/25/2013 12:24 PM, David Miller wrote:
>> From: Alexander Duyck <alexander.h.duyck@intel.com>
>> Date: Thu, 25 Apr 2013 11:29:04 -0700
>>
>> diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
>> index b65441d..23854b5 100644
>> --- a/net/core/rtnetlink.c
>> +++ b/net/core/rtnetlink.c
>> @@ -1072,7 +1072,7 @@ static int rtnl_dump_ifinfo(struct sk_buff *skb, struct netlink_callback *cb)
>>  	rcu_read_lock();
>>  	cb->seq = net->dev_base_seq;
>>  
>> -	if (nlmsg_parse(cb->nlh, sizeof(struct rtgenmsg), tb, IFLA_MAX,
>> +	if (nlmsg_parse(cb->nlh, sizeof(struct ifinfomsg), tb, IFLA_MAX,
>>  			ifla_policy) >= 0) {
>>  
>>  		if (tb[IFLA_EXT_MASK])
>> @@ -1922,7 +1922,7 @@ static u16 rtnl_calcit(struct sk_buff *skb, struct nlmsghdr *nlh)
>>  	u32 ext_filter_mask = 0;
>>  	u16 min_ifinfo_dump_size = 0;
>>  
>> -	if (nlmsg_parse(nlh, sizeof(struct rtgenmsg), tb, IFLA_MAX,
>> +	if (nlmsg_parse(nlh, sizeof(struct ifinfomsg), tb, IFLA_MAX,
>>  			ifla_policy) >= 0) {
>>  		if (tb[IFLA_EXT_MASK])
>>  			ext_filter_mask = nla_get_u32(tb[IFLA_EXT_MASK]);
> 
> I thought that as well.  I tried reverting it and the issue is still there.
> 
> However, I do think this may be part of the issue since I added a printk
> to dump nlmsg_attrlen before going into the nlmsg_parse and with
> ifinfomsg the attrlen is -12, with rtgenmsg it is 0.

I wonder if we are seeing two ways tools are making these calls, some are
passing rtgenmsg and some are passing ifinfomsg.  The latter, I am mostly
convinced, is what we must see here from properly written applications.

That would be really unfortunate, but seeing a nlmsg_attrlen() of -12 would
seem to confirm that a rtgenmsg was used.

I guess you're using iproute2?