[PATCH v2] ring: convert to C11 atomics where practical

[Stephen Hemminger <stephen@networkplumber.org>]

This is split out from the atomic deprecation series. It converts lib/ring
off rte_atomic32 and onto the C11 memory model, except where the C11 version
has a noticeable performance drop on x86 with GCC.

The pre-existing C11 and GCC-builtin paths lived in separate headers with
substantial duplication. After this series, only the MP head CAS
(__rte_ring_headtail_move_head_mt) retains separate implementations;
everything else is shared. Patch 2 documents the reason for keeping the GCC
builtin on the MP head CAS.

The default RTE_USE_C11_MEM_MODEL selection per architecture is unchanged.

v2 - consolidate cleanup patches
   - fix the memory order on first load in _st case.
     it was going back/forth across the patches

Stephen Hemminger (3):
  ring: split single thread vs multi-thread cases
  ring: use GCC builtin as alternative to rte_atomic32
  ring: cleanup the C11 code

 lib/ring/meson.build                          |   2 +-
 lib/ring/rte_ring_c11_pvt.h                   |  62 +++-------
 lib/ring/rte_ring_elem_pvt.h                  | 116 ++++++++++++++++--
 ..._ring_generic_pvt.h => rte_ring_gcc_pvt.h} |  58 +++------
 lib/ring/rte_ring_hts_elem_pvt.h              |   8 +-
 lib/ring/soring.c                             |  34 ++---
 6 files changed, 159 insertions(+), 121 deletions(-)
 rename lib/ring/{rte_ring_generic_pvt.h => rte_ring_gcc_pvt.h} (65%)

-- 
2.53.0