On Fri, Mar 02, 2018 at 12:31:41PM +0800, Boqun Feng wrote: > On Thu, Mar 01, 2018 at 10:37:58AM -0800, Paul E. McKenney wrote: > > On Thu, Mar 01, 2018 at 09:49:06AM -0800, Paul E. McKenney wrote:
[ . . . ] > > And as Andrea pointed out off-list, I did indeed mess up Boqun's change. > > I forgot to change the "irreflexive" into "acyclic". Applying that change > > makes everything work. > > > > Please accept my apologies for my confusion! > > > > np, also I should have provided a proper patch for your testing. > > For this Alan's patch, feel free to add: > > Reviewed-by: Boqun Feng <[email protected]> Alan's last submission was still RFC, so I have not yet queued it. So this ball is still in Alan's court. Thanx, Paul > Regards, > Boqun > > > Thanx, Paul > > > > > > > I prefer this because we already treat "gp" as "strong-fence", which > > > > > already is a "rcu-link". > > > > > > > > That's a good point; it had not occurred to me. > > > > > > And if I remove the "gp" but leave the last line, it does properly > > > classify the two new litmus tests. > > > > > > Thanx, Paul > > > > > > > > Also, recurisively extending rcu-fence with > > > > > itself is exactly calculating the transitive closure, which we can > > > > > avoid > > > > > by using a "acycle" rule. Besides, it looks more consistent with hb > > > > > and > > > > > pb. > > > > > > > > That _had_ occurred to me. But I couldn't see any way to do it while > > > > still defining rcu-fence correctly. > > > > > > ------------------------------------------------------------------------ > > > > > > diff --git a/tools/memory-model/linux-kernel.cat > > > b/tools/memory-model/linux-kernel.cat > > > index 1e5c4653dd12..75d3c225146c 100644 > > > --- a/tools/memory-model/linux-kernel.cat > > > +++ b/tools/memory-model/linux-kernel.cat > > > @@ -106,12 +106,11 @@ let rcu-link = hb* ; pb* ; prop > > > * Any sequence containing at least as many grace periods as RCU > > > read-side > > > * critical sections (joined by rcu-link) acts as a generalized strong > > > fence. > > > *) > > > -let rec rcu-fence = gp | > > > +let rec rcu-fence = > > > (gp ; rcu-link ; rscs) | > > > (rscs ; rcu-link ; gp) | > > > (gp ; rcu-link ; rcu-fence ; rcu-link ; rscs) | > > > - (rscs ; rcu-link ; rcu-fence ; rcu-link ; gp) | > > > - (rcu-fence ; rcu-link ; rcu-fence) > > > + (rscs ; rcu-link ; rcu-fence ; rcu-link ; gp) > > > > > > (* rb orders instructions just as pb does *) > > > let rb = prop ; rcu-fence ; hb* ; pb* > >
