Re: [PATCH V5] powercap/drivers/idle_injection: Add an idle injection framework

From: Peter Zijlstra
Date: Thu Jun 07 2018 - 04:32:50 EST

On Thu, Jun 07, 2018 at 10:18:27AM +0200, Daniel Lezcano wrote:
> So IIUC, neither atomic or WRITE|READ_ONCE are necessary in this code
> because of the wake_up_process() barrier is enough, right ?

I didn't look hard enough; if there ever is a time where the loads and
stores happen concurrently, you need READ/WRITE_ONCE(). If there is no
concurrency on the variables, you don't need anything.

Neither atomic_read/set() nor REAd/WRITE_ONCE() will help with ordering,
which is what the wake_up_process() would provide here, different things