[PATCH v4 00/29] remove rte_smp_XX barriers

[Stephen Hemminger <stephen@networkplumber.org>]

This patch series completes the removal of rte_smp_XX barrier
functions that was announced over five years ago (20.05).

In the process several race conditions were found and fixed. See
patches 3, 4 and 17, marked with Fixes: and Cc: stable. Patch 2 is
also marked for stable because 3 and 4 do not build with clang
without it.

Most of this is mechanical with AI assistance, so strongly encourage
maintainers to take a good look.

Barriers ordering memory writes against a device doorbell now use
rte_io_wmb() rather than an SMP barrier; on arm64 that is dmb oshst
instead of dmb ishst. In some cases the C11 form gives marginal
performance gains.

The lock-free stack patch measured faster than the generic version it
replaces, up to 63% on a 32-core x86 box; the numbers are in that
patch's commit message.

Patch 19 keeps the Peterson lock test, converted to C11 atomics, with
the seq_cst fence and rte_mb() as its two cases. It comes before
patch 20, which holds the last rte_smp_mb() caller, so x86 builds
with tests enabled stay bisectable. Tested on x86, arm and riscv;
still untested on ppc and loongarch.

Patch 18 has no ack. Bruce, yours landed on 17; 18 changed since.

Left for follow-up: device read barriers in patches 6, 8 and 14 are
acquire fences where rte_io_rmb() would match the write side (same
generated code today, so no regression). And the net/thunderx mailbox
flags in patch 10 are plain bitfields that need to be atomic, which
is pre-existing.

v4 - rebase on main, which obsoleted the netvsc patch; address review
     comments from Konstantin, Marat, David and Wei Hu; collect tags

Stephen Hemminger (29):
  bpf: replace deprecated SMP barriers with C11 fences
  bus/vmbus: remove packed attribute from ring buffer
  bus/vmbus: fix ring buffer ordering on weakly ordered CPUs
  bus/vmbus: fix missing acquire on receive ring index
  bus/vmbus: replace SMP barriers with C11 memory fences
  drivers/baseband: convert rte_smp_rmb to fence
  net/hinic: replace rte_smp_rmb
  net/intel: replace rte_smp_rmb
  net/virtio: replace rte_smp_rmb
  net/thunderx: replace deprecated SMP barriers
  stack: always use C11 memory model implementation
  ring: replace SMP read barrier with C11 acquire fence
  crypto/virtio: update comment reference to rte_smp_rmb
  crypto/caam_jr: replace rte_smp_rmb
  crypto/caam_jr: use IO barrier before job ring doorbell
  crypto/octeontx: use IO barrier before doorbell
  event/sw: fix unlinks in progress counter races
  event/sw: replace SMP barriers with C11 atomics
  test/barrier: convert to C11 atomics
  eal/x86: move optimized fence out of SMP barrier
  common/octeontx: remove redundant barrier in mbox
  mempool/octeontx: use IO barrier in pool destroy
  event/octeontx: replace deprecated SMP barriers
  event/dpaa2: replace deprecated barrier in selftest
  event/dsw: replace SMP barriers with release fences
  event/opdl: replace SMP barriers with C11 atomics
  net/virtio: replace deprecated barrier in avail index update
  eal: remove stale SMP barrier in rte_service
  eal: remove rte_smp_XX

 app/test/test_barrier.c                       |  71 ++++----
 devtools/checkpatches.sh                      |   8 -
 doc/guides/rel_notes/deprecation.rst          |   8 -
 doc/guides/rel_notes/release_26_11.rst        |  11 ++
 .../fpga_5gnr_fec/rte_fpga_5gnr_fec.c         |   8 +-
 drivers/baseband/fpga_lte_fec/fpga_lte_fec.c  |  12 +-
 drivers/bus/vmbus/private.h                   |  12 +-
 drivers/bus/vmbus/rte_vmbus_reg.h             |   4 +-
 drivers/bus/vmbus/vmbus_bufring.c             |  22 +--
 drivers/bus/vmbus/vmbus_channel.c             |  13 +-
 drivers/common/octeontx/octeontx_mbox.c       |   6 +-
 drivers/crypto/caam_jr/caam_jr.c              |   5 +-
 .../crypto/octeontx/otx_cryptodev_hw_access.h |   4 +-
 drivers/crypto/virtio/virtqueue.h             |   8 +-
 drivers/event/dpaa2/dpaa2_eventdev_selftest.c |   4 +-
 drivers/event/dsw/dsw_event.c                 |   8 +-
 drivers/event/octeontx/ssovf_evdev_selftest.c |   6 +-
 drivers/event/octeontx/ssovf_worker.c         |   8 +-
 drivers/event/opdl/opdl_evdev.c               |   8 +-
 drivers/event/sw/sw_evdev.c                   |  37 +++--
 drivers/event/sw/sw_evdev.h                   |  11 +-
 drivers/event/sw/sw_evdev_scheduler.c         |  24 ++-
 drivers/mempool/octeontx/octeontx_fpavf.c     |   4 +-
 drivers/net/hinic/base/hinic_pmd_cmdq.c       |   3 +-
 drivers/net/hinic/base/hinic_pmd_mgmt.c       |   2 +-
 drivers/net/intel/ice/ice_rxtx.c              |   2 +-
 drivers/net/intel/ixgbe/ixgbe_rxtx.c          |   2 +-
 drivers/net/thunderx/base/nicvf_hw.c          |   3 +-
 drivers/net/thunderx/base/nicvf_plat.h        |   5 +-
 drivers/net/virtio/virtqueue.h                |  22 +--
 lib/bpf/bpf_pkt.c                             |  26 +--
 lib/eal/arm/include/rte_atomic_32.h           |   6 -
 lib/eal/arm/include/rte_atomic_64.h           |   6 -
 lib/eal/common/rte_service.c                  |   1 -
 lib/eal/include/generic/rte_atomic.h          |  61 -------
 lib/eal/loongarch/include/rte_atomic.h        |   6 -
 lib/eal/ppc/include/rte_atomic.h              |   6 -
 lib/eal/riscv/include/rte_atomic.h            |   6 -
 lib/eal/x86/include/rte_atomic.h              |  41 ++---
 lib/ring/rte_ring_gcc_pvt.h                   |   6 +-
 lib/stack/meson.build                         |   1 -
 lib/stack/rte_stack_lf.h                      |   4 -
 lib/stack/rte_stack_lf_generic.h              | 153 ------------------
 43 files changed, 226 insertions(+), 438 deletions(-)
 delete mode 100644 lib/stack/rte_stack_lf_generic.h

-- 
2.53.0