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Re: [PATCH tip/core/rcu 07/13] rcu: Add smp_mb__after_atomic() to sync_exp_work_done()

From Peter Zijlstra <peterz@infradead.org>
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 11:20 +0200
Message-ID <tvJ50-Rx-15@gated-at.bofh.it> (permalink)
References <tvtMC-6Uu-3@gated-at.bofh.it> <tvtMC-6Uu-1@gated-at.bofh.it>
Organization linux.* mail to news gateway

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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.

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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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