1. Use __atomic builtins instead of __sync builtins. __sync builtins may have unecessarily strict memory ordering which is not ideal for weakly ordered memory model e.g. Arm architecture.
2. Review use of atomics to ensure correct memory ordering on non-TSO machines.

 Files using __sync builtins:

~/vpp (master)$ ag -l __sync
src/vpp/stats/stats.c
src/plugins/lb/lb.c
src/plugins/nat/nat_det.h
src/plugins/kubeproxy/kp.c
src/plugins/ioam/analyse/ioam_summary_export.c
src/plugins/ioam/analyse/ip6/node.c
src/plugins/ioam/analyse/ioam_analyse.h
src/plugins/ioam/export-common/ioam_export.h
src/plugins/dpdk/device/device.c
src/vpp-api/java/jvpp-common/jvpp_common.h
src/vlib/buffer_funcs.h
src/vlib/threads.h
src/vlib/threads.c
src/vlib/unix/cj.c
src/svm/svm_fifo.c
src/svm/memfd.h
src/svm/svm_fifo.h
src/svm/ssvm.h
src/vppinfra/bihash_template.h
src/vppinfra/smp.h
src/vppinfra/elog.c
src/vppinfra/bihash_template.c
src/vppinfra/mheap.c
src/vppinfra/maplog.h
src/vppinfra/lock.h
src/vppinfra/clib.h
src/vnet/map/map.h
src/vnet/tcp/builtin_client.c
src/vnet/util/refcount.h
src/vnet/flow/flow_report_classify.c
src/vnet/mfib/mfib_forward.c
src/vnet/mfib/mfib_signal.c
src/vnet/dns/dns.h
src/vnet/classify/vnet_classify.c
src/vnet/devices/ssvm/node.c
src/vnet/devices/ssvm/ssvm_eth.c
src/vnet/devices/virtio/vhost-user.c
src/vnet/pg/output.c
src/vnet/interface.h
src/vnet/ip/ip4_mtrie.c
extras/libmemif/src/main.c