Note: the ifnet iterators were created to hide struct ifnet from drivers. For the core parts of the network stack (and netlink is one of) it is alright to dereference struct ifnet. The provided KPI if_foreach_group() while hides struct ifnet it actually assumes that KPI user knows struct ifgroup, which is as also pretty internal to the stack. Other than that the patch is good as is. I won't request you to remove the new KPI and use CK_STAILQ_FOREACH(ifgl, &ifp->if_groups, ifgl_next) straight in the netlink code. Maybe makes sense to add an XXX comment above if_foreach_group() mentioning that KPI is questionable and may change later.