[PATCH v5] eal: add seqlock

[Honnappa Nagarahalli]

<snip>

> > +__rte_experimental
> > +static inline bool
> > +rte_seqlock_read_retry(const rte_seqlock_t *seqlock, uint32_t
> > +begin_sn) {
> > +	uint32_t end_sn;
> > +
> > +	/* An odd sequence number means the protected data was being
> > +	 * modified already at the point of the rte_seqlock_read_begin()
> > +	 * call.
> > +	 */
> > +	if (unlikely(begin_sn & 1))
> > +		return true;
> > +
> > +	/* make sure the data loads happens before the sn load */
> > +	rte_atomic_thread_fence(__ATOMIC_ACQUIRE);
> 
> In ARMv8, the rte_atomic_thread_fence(__ATOMIC_ACQUIRE) and
> rte_smp_rmb() both output 'dma ishld'
> Suggest use rte_smp_rmb(), please see below comment.
rte_smp_xxx APIs are deprecated. Please check [1]

[1] https://www.dpdk.org/blog/2021/03/26/dpdk-adopts-the-c11-memory-model/

<snip>