Messages in this thread | | | Date | Sat, 3 Feb 2018 17:10:06 -0500 (EST) | From | Alan Stern <> | Subject | Re: [GIT PULL tools] Linux kernel memory model |
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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.
Alan
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