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Date:   Thu, 12 Jul 2018 20:05:11 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc:     Alan Stern <stern@rowland.harvard.edu>,
        Andrea Parri <andrea.parri@amarulasolutions.com>,
        Will Deacon <will.deacon@arm.com>,
        LKMM Maintainers -- Akira Yokosawa <akiyks@gmail.com>,
        Boqun Feng <boqun.feng@gmail.com>,
        Daniel Lustig <dlustig@nvidia.com>,
        David Howells <dhowells@redhat.com>,
        Jade Alglave <j.alglave@ucl.ac.uk>,
        Luc Maranget <luc.maranget@inria.fr>,
        Nicholas Piggin <npiggin@gmail.com>,
        Kernel development list <linux-kernel@vger.kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH v2] tools/memory-model: Add extra ordering for locks and
 remove it for ordinary release/acquire
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On Thu, Jul 12, 2018 at 10:28:38AM -0700, Paul E. McKenney wrote:
> Look for the uses of raw_spin_lock_irq_rcu_node() and friends in
> kernel/rcu and include/linux/*rcu*, along with the explanation in
> Documentation/RCU/Design/Memory-Ordering/Tree-RCU-Memory-Ordering.html
> 
> I must confess that I am not following exactly what Peter is calling
> out as the failure.  My best guess is that he is leading up to his
> call for RCsc locks, but I might have missed a turn.

Yes, it is part of my call for RCsc locks.

The locking pattern is fairly simple and shows where RCpc comes apart
from expectation real nice.

Yes I helped clean up the barrier usage, but as always it'd be even
cleaner if we could just do away with the special barrier entirely.