Re: [PATCH v2 rcu 04/18] rcu: Weaken ->dynticks accesses and updates

[Linus Torvalds]

On Wed, Jul 28, 2021 at 11:12 AM Mathieu Desnoyers
<mathieu.desnoyers@xxxxxxxxxxxx> wrote:
>
> Are the percpu atomics you have in mind different from what is found in
> Documentation/core-api/this_cpu_ops.rst ?
>
> Namely this_cpu_add_return(pcp, val) in this case.

Nope.

Those are only "CPU-atomic", ie atomic wrt interrupts etc.

The RCU code wants SMP-atomic, and it's mainly that we *could* do the
addressing more efficiently.

        Linus