Re: [PATCH tip/core/rcu 01/14] rcu: Protect rcu_boost() lockless accesses with ACCESS_ONCE()

[Paul E. McKenney]

On Thu, Jan 08, 2015 at 10:41:54PM -0800, Davidlohr Bueso wrote:
> On Thu, 2015-01-08 at 07:22 -0800, Paul E. McKenney wrote:
> > > Didn't we just obsolete ACCESS_ONCE with that {READ,WRITE}_ONCE stuff?
> > 
> > Indeed we did!  But that was after I did this commit back on October 29th.
> > 
> > I am planning a bulk change to READ_ONCE() and ASSIGN_ONCE() either as
> > the last patch for 3.20 or as the first one for 3.21.  Probably as the
> > first for 3.21 to minimize rebasing hassles with any needed 3.20 fixes.
> 
> That reminds me, I think the new conversion for stores will most likely
> introduce silly arg bugs:
> 
> -       ACCESS_ONCE(a) = b;
> +       ASSIGN_ONCE(b, a);

I was planning to do mine by hand for this sort of reason.

Or are you thinking of something more subtle than the case where
"b" is an unparenthesized comma-separated expression?

							Thanx, Paul

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