Service core statistics MT safety

[Honnappa Nagarahalli]

<snip>
> >>
> >>> From: Mattias Rönnblom [mailto:mattias.ronnblom at ericsson.com]
> >>> Sent: Monday, 27 June 2022 13.06
> >>>
> >>> Hi.
> >>>
> >>> Is it safe to enable stats on MT safe services?
> >>>
> >>> https://github.com/DPDK/dpdk/blob/main/lib/eal/common/rte_service.c#
> >>> L3
> >>> 6
> >>> 6
> >>>
> >>> It seems to me this would have to be an __atomic_add for this code
> >>> to produce deterministic results.
> >>
> >> I agree. The same goes for the 'calls' field.
> > The calling function does the locking.
> > https://github.com/DPDK/dpdk/blob/main/lib/eal/common/rte_service.c#L3
> > 98
> >
> > For more information you can look at:
> > https://github.com/DPDK/dpdk/blob/main/lib/eal/include/rte_service.h#L
> > 120
> >
> 
> What about the
> https://github.com/DPDK/dpdk/blob/main/lib/eal/common/rte_service.c#L404
> call (for MT safe services)?
> 
> There's no lock held there.
Good point.
This is the case where the service running in service cores is MT safe. However, the stats are incremented outside of the MT Safety mechanism employed by the service. So, yes, this and other updates in the function 'service_runner_do_callback' need to be updated atomically.