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Date:   Tue, 5 Jul 2022 19:36:54 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Nicholas Piggin <npiggin@gmail.com>
Cc:     Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>,
        Waiman Long <longman@redhat.com>,
        Boqun Feng <boqun.feng@gmail.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 06/13] locking/qspinlock: merge qspinlock_paravirt.h into
 qspinlock.c
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On Tue, Jul 05, 2022 at 07:20:37PM +0200, Peter Zijlstra wrote:
> On Tue, Jul 05, 2022 at 12:38:13AM +1000, Nicholas Piggin wrote:
> > There isn't much reason to keep these separate.
> 
> The reason was so that other paravirt implementations could be added.
> 
> The CNA thing was also implemented this way...

Also, (TIL) s390 seems to have a copy of all this:

  b96f7d881ad9 ("s390/spinlock: introduce spinlock wait queueing")

it might be nice if it were possible to fold that back into this with a
different paravirt implementation; but I've not looked at it in any
great detail yet.