net: rtnetlink: Add UAPI for obtaining L3 offload xstats

Add a new IFLA_STATS_LINK_OFFLOAD_XSTATS child attribute, IFLA_OFFLOAD_XSTATS_L3_STATS, to carry statistics for traffic that takes place in a HW router. The offloaded HW stats are designed to allow per-netdevice enablement and disablement. Additionally, as a netdevice is configured, it may become or cease being suitable for binding of a HW counter. Both of these aspects need to be communicated to the userspace. To that end, add another child attribute, IFLA_OFFLOAD_XSTATS_HW_S_INFO: - attr nest IFLA_OFFLOAD_XSTATS_HW_S_INFO - attr nest IFLA_OFFLOAD_XSTATS_L3_STATS - attr IFLA_OFFLOAD_XSTATS_HW_S_INFO_REQUEST - {0,1} as u8 - attr IFLA_OFFLOAD_XSTATS_HW_S_INFO_USED - {0,1} as u8 Thus this one attribute is a nest that can be used to carry information about various types of HW statistics, and indexing is very simply done by wrapping the information for a given statistics suite into the attribute that carries the suite is the RTM_GETSTATS query. At the same time, because _HW_S_INFO is nested directly below IFLA_STATS_LINK_OFFLOAD_XSTATS, it is possible through filtering to request only the metadata about individual statistics suites, without having to hit the HW to get the actual counters.

PMPetr Machata committed 4 years ago