Re: [RFC v2] net/af_packet: make stats reset reliable

[Stephen Hemminger <stephen@networkplumber.org>]

On Thu, 2 May 2024 19:37:28 +0200
Mattias Rönnblom <hofors@lysator.liu.se> wrote:

> > 
> > Do we need to declare count as '_Atomic', I wasn't planning to make
> > variable _Atomic. This way assignment won't introduce any memory barrier.
> >   
> 
> To use atomics in DPDK, the current requirements seems to be to use 
> RTE_ATOMIC(). That macro expands to _Atomic in enable_stdatomic=true 
> builds, and nothing otherwise.
> 
> Carefully crafted code using atomics will achieved the same performance 
> and be more correct than the non-atomic variant. However, in practice, I 
> think the non-atomic variant is very likely to produce the desired results.

You are confusing atomic usage for thread safety, with the necessity
of compiler barriers. 

Stats should not be volatile.