Re: [PATCH tip/core/rcu 08/10] rcu: Add a TINY_PREEMPT_RCU

[Steven Rostedt]

On Tue, 2010-08-17 at 12:04 -0400, Steven Rostedt wrote:

> > Then we could go for the simpler:
> > 
> >   	--t->rcu_read_lock_nesting;
> >  	barrier();
> >         if (t->rcu_read_lock_nesting == 0 &&
> >              unlikely((t->rcu_read_unlock_special))
> 
> Yeah, that's what I meant, I was too lazy to remove the ACCESS_ONCE()
> from the cut and paste I did.
> 
> > 
> > Which puts a constraint across all memory accesses. I'd be fine with
> > that if you are afraid of too much micro-optimization (e.g. my
> > barrier2(a, b) proposal).
> 
> Not afraid, but just too much code for a simple solution.

IOW,

I think just pulling out the '--' and adding the barrier() is the proper
solution here. Compiler barriers are rather cheap.

Can we all agree on this solution?

-- Steve


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