Re: [RFC] introduce synchronize_sched_{enter,exit}()

From: Oleg Nesterov
Date: Mon Sep 30 2013 - 13:05:18 EST


On 09/30, Peter Zijlstra wrote:
>
> On Mon, Sep 30, 2013 at 04:24:00PM +0200, Peter Zijlstra wrote:
> > For that we'd have to decrement xxx->gp_count from cb_rcu_func(),
> > wouldn't we?
> >
> > Without that there's no guarantee the fast path readers will have a MB
> > to observe the write critical section, unless I'm completely missing
> > something obviuos here.
>
> Duh.. we should be looking at gp_state like Paul said.

Yes, yes, that is why we have xxx_is_idle(). Its name is confusing
even ignoring "xxx".

OK, I'll try to invent the naming (but I'd like to hear suggestions ;)
and send the patch. I am going to add "exclusive" and "rcu_domain/ops"
later, currently percpu_rw_semaphore needs ->rw_sem anyway.

Oleg.

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