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Groups > linux.kernel > #1623157
| From | "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH tip/core/rcu 07/13] rcu: Add smp_mb__after_atomic() to sync_exp_work_done() |
| Date | 2017-04-13 18:20 +0200 |
| Message-ID | <tvPDs-5oA-13@gated-at.bofh.it> (permalink) |
| References | <tvtMC-6Uu-3@gated-at.bofh.it> <tvtMC-6Uu-1@gated-at.bofh.it> <tvJ50-Rx-15@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
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.
Thanx, Paul
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[PATCH tip/core/rcu 07/13] rcu: Add smp_mb__after_atomic() to sync_exp_work_done() "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-04-12 19:00 +0200
Re: [PATCH tip/core/rcu 07/13] rcu: Add smp_mb__after_atomic() to sync_exp_work_done() Peter Zijlstra <peterz@infradead.org> - 2017-04-13 11:20 +0200
Re: [PATCH tip/core/rcu 07/13] rcu: Add smp_mb__after_atomic() to sync_exp_work_done() Peter Zijlstra <peterz@infradead.org> - 2017-04-13 11:40 +0200
Re: [PATCH tip/core/rcu 07/13] rcu: Add smp_mb__after_atomic() to sync_exp_work_done() "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-04-13 18:20 +0200
Re: [PATCH tip/core/rcu 07/13] rcu: Add smp_mb__after_atomic() to sync_exp_work_done() Peter Zijlstra <peterz@infradead.org> - 2017-04-13 18:30 +0200
Re: [PATCH tip/core/rcu 07/13] rcu: Add smp_mb__after_atomic() to sync_exp_work_done() "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-04-13 19:00 +0200
Re: [PATCH tip/core/rcu 07/13] rcu: Add smp_mb__after_atomic() to sync_exp_work_done() Peter Zijlstra <peterz@infradead.org> - 2017-04-13 19:20 +0200
Re: [PATCH tip/core/rcu 07/13] rcu: Add smp_mb__after_atomic() to sync_exp_work_done() "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-04-13 19:50 +0200
Re: [PATCH tip/core/rcu 07/13] rcu: Add smp_mb__after_atomic() to sync_exp_work_done() Peter Zijlstra <peterz@infradead.org> - 2017-04-13 20:00 +0200
Re: [PATCH tip/core/rcu 07/13] rcu: Add smp_mb__after_atomic() to sync_exp_work_done() Peter Zijlstra <peterz@infradead.org> - 2017-04-13 20:10 +0200
Re: [PATCH tip/core/rcu 07/13] rcu: Add smp_mb__after_atomic() to sync_exp_work_done() "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-04-20 01:30 +0200
Re: [PATCH tip/core/rcu 07/13] rcu: Add smp_mb__after_atomic() to sync_exp_work_done() "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-04-20 01:30 +0200
Re: [PATCH tip/core/rcu 07/13] rcu: Add smp_mb__after_atomic() to sync_exp_work_done() Peter Zijlstra <peterz@infradead.org> - 2017-04-20 13:20 +0200
Re: [PATCH tip/core/rcu 07/13] rcu: Add smp_mb__after_atomic() to sync_exp_work_done() "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-04-20 17:10 +0200
Re: [PATCH tip/core/rcu 07/13] rcu: Add smp_mb__after_atomic() to sync_exp_work_done() Peter Zijlstra <peterz@infradead.org> - 2017-04-20 17:10 +0200
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