On Sat, Feb 03, 2018 at 05:10:06PM -0500, Alan Stern wrote: > On Sat, 3 Feb 2018, Paul E. McKenney wrote: > > > Please see below for an initial patch to this effect. This activity > > proved to be more productive than expected for these tests, which certainly > > supports our assertion that locking needs more testing... > > > > MP+polocks.litmus > > MP+porevlocks.litmus > > > > These are allowed by the current model, which surprised me a bit, > > given that even powerpc would forbid them. Is the rationale > > that a lock-savvy compiler could pull accesses into the lock's > > critical section and then reorder those accesses? Or does this > > constitute a bug in our model of locking? > > > > (And these were allowed when I wrote recipes.txt, embarrassingly > > enough...) > > > > Z6.0+pooncelock+poonceLock+pombonce.litmus > > > > This was forbidden when I wrote recipes.txt, but now is allowed. > > The header comment for smp_mb__after_spinlock() makes it pretty > > clear that it must be forbidden. So this one is a bug in our > > model of locking. > > I just tried testing these under the most recent version of herd, and > all three were forbidden. And they do for me as well once I upgraded to the most recent version of herd. Whew!!! Boy, we weren't kidding when we said that you need to us the latest and greatest herd7, now were we? ;-) Thanx, Paul
