Re: [patch 3/3] tick: Annotate tick_do_timer_cpu data races

[Peter Zijlstra]

On Wed, Dec 16, 2020 at 01:19:31PM -0800, Paul E. McKenney wrote:
> Given that there is no optimization potential, then the main reason to use
> data_race() instead of *_ONCE() is to prevent KCSAN from considering the
> accesses when looking for data races.  But that is mostly for debugging
> accesses, in cases when these accesses are not really part of the
> concurrent algorithm.
> 
> So if I understand the situation correctly, I would be using *ONCE().

Huh, what, why?

The code doesn't need READ_ONCE(), it merely wants to tell kasan that
the race it observes is fine and as to please shut up.

IOW data_race() is accurate and right.