CC: Johannes

On 9/6/25 12:19 AM, Jacob Keller wrote:

On 9/4/2025 3:01 PM, Asbjørn Sloth Tønnesen wrote:

quoted

This patch adds support for NLA_POLICY_NESTED_ARRAY() policies.

Example spec (from future wireguard.yaml):
-
   name: wgpeer
   attributes:
     -
       name: allowedips
       type: indexed-array
       sub-type: nest
       nested-attributes: wgallowedip

yields NLA_POLICY_NESTED_ARRAY(wireguard_wgallowedip_nl_policy).

This doesn't change any currently generated code, as it isn't
used in any specs currently used for generating code.

Signed-off-by: Asbjørn Sloth Tønnesen <redacted>
---

Is this keyed of off the sub-type? Does you mean that all the existing
uses of 'sub-type: nest' don't generate code today? Or that this
_attr_policy implementation is not called yet?

Thanks for the reviews. Yeah, it is a careful wording, because we have
specs matching it, but there aren't any source files that triggers
ynl-gen to generate code based on those specs.

Therefore this patch, doesn't result in any code changes when running:
$ ./tools/net/ynl/ynl-regen.sh -f

Actually ynl-gen generates a fictive "{ .type = NLA_INDEXED_ARRAY, }"
policy, without this patch, leading to a build failure.

I checked and we have quite a number of uses:

quoted

$ rg 'sub-type: nest'
Documentation/netlink/specs/nlctrl.yaml

 >> [..]

quoted

Documentation/netlink/specs/tc.yaml
[..]
Documentation/netlink/specs/rt-link.yaml
[..]
Documentation/netlink/specs/nl80211.yaml
[..]

None of those currently have a generated netlink policy.

These are the netlink policies currently generated by ynl-gen:
$ git grep -h -B1 'YNL-GEN kernel source' | grep '^/\*[^ ]'
/*      Documentation/netlink/specs/dpll.yaml */
/*      Documentation/netlink/specs/ovpn.yaml */
/*      Documentation/netlink/specs/team.yaml */
/*      Documentation/netlink/specs/lockd.yaml */
/*      Documentation/netlink/specs/nfsd.yaml */
/*      Documentation/netlink/specs/netdev.yaml */
/*      Documentation/netlink/specs/devlink.yaml */
/*      Documentation/netlink/specs/handshake.yaml */
/*      Documentation/netlink/specs/fou.yaml */
/*      Documentation/netlink/specs/mptcp_pm.yaml */
/*      Documentation/netlink/specs/net_shaper.yaml */

Johannes introduced NLA_NESTED_ARRAY and the NLA_POLICY_NESTED_ARRAY()
macro in commit 1501d13596b9 for use in nl80211, and it's therefore
used in net/wireless/nl80211.c, but outside of that the macro is
only sparsely adopted (only by mac80211_hwsim.c and nf_tables_api.c).

Wireguard adopts the macro in this RFC patch:
https://lore.kernel.org/netdev/20250904220255.1006675-2-ast@fiberby.net/ (local)