Re: [PATCH 1/5] netlink: extended ACK reporting

[David Ahern <dsa@cumulusnetworks.com>]

On 4/8/17 2:40 PM, Jiri Pirko wrote:
> Sat, Apr 08, 2017 at 08:37:01PM CEST, johannes@sipsolutions.net wrote:
>> On Sat, 2017-04-08 at 20:34 +0200, Jiri Pirko wrote:
>>> nla_total_size(sizeof(u32));
>>>> +			if (extack &&
>>>> +			    (extack->missing_attr || extack-
>>>>> bad_attr))
>>>
>>> Attr could be 0, right? I know that on the most of the places 0 is
>>> UNSPEC, but I'm pretty sure not everywhere.

perhaps I misunderstand something, but nla_parse suggests attribute type
can not be 0:

int nla_parse(struct nlattr **tb, int maxtype, const struct nlattr *head,
              int len, const struct nla_policy *policy,
              struct netlink_ext_ack *extack)
{
	...

        nla_for_each_attr(nla, head, len, rem) {
                u16 type = nla_type(nla);

                if (type > 0 && type <= maxtype) {
			...
                        tb[type] = (struct nlattr *)nla;
                }
        }


> Also, could you please attach a patch to iproute2 for example which
> would make use of this. I just want to make sure it clicks.

I have follow on patches to Johannes' set that plumbs extack for
rtnetlink doit function and iproute2. will send later.