Re: [PATCH iproute2] devlink: Ignore unknown attributes

On 1/19/18 3:40 PM, Stephen Hemminger wrote:

quoted

mnl_attr_type_valid calls mnl_attr_get_type which does attr->nla_type &
NLA_TYPE_MASK. Since you are no longer acknowledging the return code of
mnl_attr_type_valid, you don't care about its checks so you might as
well not call it. I don't see anything in libmnl that checks that
mnl_attr_type_valid is invoked on an attr, so hence my question -- given
the change above why call it all?

ok. I see the error in my thinking.

 The part that matters is:

static int attr_cb(const struct nlattr *attr, void *data)
{
	const struct nlattr **tb = data;
	int type;

	if (mnl_attr_type_valid(attr, DEVLINK_ATTR_MAX) < 0)         << makes sure that type < DEVLINK_ATTR_MAX
		return MNL_CB_OK;

	type = mnl_attr_get_type(attr);
	if (mnl_attr_validate(attr, devlink_policy[type]) < 0)        << this part doesn't matter really
		return MNL_CB_ERROR;

	tb[type] = attr;					<< necessary so that tb[] is filled in.
	return MNL_CB_OK;
}