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Date:   Wed, 17 Apr 2019 12:19:03 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Waiman Long <longman@redhat.com>
Cc:     Ingo Molnar <mingo@redhat.com>, Will Deacon <will.deacon@arm.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        linux-kernel@vger.kernel.org, x86@kernel.org,
        Davidlohr Bueso <dave@stgolabs.net>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Tim Chen <tim.c.chen@linux.intel.com>,
        huang ying <huang.ying.caritas@gmail.com>
Subject: Re: [PATCH v4 08/16] locking/rwsem: Make rwsem_spin_on_owner()
 return owner state
Message-ID: <20190417101903.GD4038@hirez.programming.kicks-ass.net>
References: <20190413172259.2740-1-longman@redhat.com>
 <20190413172259.2740-9-longman@redhat.com>
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On Sat, Apr 13, 2019 at 01:22:51PM -0400, Waiman Long wrote:
> In the special case that there is no active lock and the handoff bit
> is set, optimistic spinning has to be stopped.

This makes me think this should've been _before_ you added the handoff
bit. So that when you introduce the handoff, everything is solid.