Merge branch 'ip-stats' into next

Petr Machata  says:

====================

A new rtnetlink message, RTM_SETSTATS, has been added recently in kernel
commit ca0a53dcec94 ("Merge branch 'net-hw-counters-for-soft-devices'").

At the same time, RTM_GETSTATS has been around for a while. The users of
this API are spread in a couple different places: "ip link xstats" reads
stats from the IFLA_STATS_LINK_XSTATS and _XSTATS_SLAVE subgroups, "ip
link afstats" then reads IFLA_STATS_AF_SPEC.

Finally, to read IFLA_STATS_LINK_OFFLOAD_XSTATS, one would use ifstats.
This does not seem to be a good fit for IFLA_OFFLOAD_XSTATS_HW_S_INFO in
particular.

The obvious place to expose all these offload stats suites would be
under a new link subcommand "ip link offload_xstats", or similar, which
would then have syntax for both showing stats and setting them.

However, this looks like a good opportunity to introduce a new top-level
command, "ip stats", that would be the go-to place to access anything
backed by RTM_GETSTATS and RTM_SETSTATS.

This patchset therefore does the following:

- It adds the new "stats" infrastructure

- It adds specifically the ability to toggle and show the suites that
  were recently added to Linux, IFLA_OFFLOAD_XSTATS_HW_S_INFO and
  IFLA_OFFLOAD_XSTATS_L3_STATS.

- It adds support to dump IFLA_OFFLOAD_XSTATS_CPU_HIT, which was not
  available under "ip" at all.

- Does all this in a way that is easy to extend for new stats suites.

The patchset proceeds as follows:

- Patches #1 and #2 lay some groundwork and tweak existing code.

- Patch #3 adds the shell of the new "ip stats" command.

- Patch #4 adds "ip stats set" and the ability to toggle l3_stats in
  particular.

- Patch #5 adds "ip stats show", but no actual stats suites.

- Patches #6-#9 add support for showing individual stats suites:
  respectively, IFLA_STATS_LINK_64, IFLA_OFFLOAD_XSTATS_CPU_HIT,
  IFLA_OFFLOAD_XSTATS_HW_S_INFO and IFLA_OFFLOAD_XSTATS_L3_STATS.

- Patch #10 adds support for monitoring stats events to "ip monitor".

- Patch #11 adds man page verbiage for the above.

The plan is to contribute support for afstats and xstats in a follow-up
patch set.

====================

Signed-off-by: David Ahern <dsahern@kernel.org>