Messages in this thread | | | Date | Thu, 13 Apr 2017 18:24:09 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH tip/core/rcu 07/13] rcu: Add smp_mb__after_atomic() to sync_exp_work_done() |
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On Thu, Apr 13, 2017 at 09:10:42AM -0700, Paul E. McKenney wrote: > On Thu, Apr 13, 2017 at 11:18:32AM +0200, Peter Zijlstra wrote: > > On Wed, Apr 12, 2017 at 09:55:43AM -0700, Paul E. McKenney wrote: > > > However, a little future-proofing is a good thing, > > > especially given that smp_mb__before_atomic() is only required to > > > provide acquire semantics rather than full ordering. This commit > > > therefore adds smp_mb__after_atomic() after the atomic_long_inc() > > > in sync_exp_work_done(). > > > > Oh!? As far as I'm away the smp_mb__{before,after}_atomic() really must > > provide full MB, no confusion about that. > > > > We have other primitives for acquire/release. > > Hmmm... Rechecking atomic_ops.txt, it does appear that you are quite > correct. Adding Will and Dmitry on CC, but dropping this patch for now.
I'm afraid that document is woefully out dated. I'm surprised it says anything on the subject.
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