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From: Qian Cai <cai@lca.pw>
To: Will Deacon <will@kernel.org>
Cc: "Paul E. McKenney" <paulmck@kernel.org>,
	Elver Marco <elver@google.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Ingo Molnar <mingo@redhat.com>,
	"Peter Zijlstra (Intel)" <peterz@infradead.org>
Subject: Re: [PATCH -next v2] locking/osq_lock: annotate a data race in osq_lock
Date: Mon, 11 May 2020 13:10:27 -0400	[thread overview]
Message-ID: <D9C5B7E9-5927-4015-BC7C-202585C5649E@lca.pw> (raw)
In-Reply-To: <20200511165441.GB23081@willie-the-truck>



> On May 11, 2020, at 12:54 PM, Will Deacon <will@kernel.org> wrote:
> 
> Hmm, I don't see how it can remove the cmpxchg(). Do you have a link to that
> discussion, please?

lore.kernel.org/lkml/20200211124753.GP14914@hirez.programming.kicks-ass.net

Correction — if compilers could prove ”prev->next != node” is always true, that cmpxchg() would not run. cpu_relax() should be sufficient to keep that “if statement” been optimized away in any case.

      reply	other threads:[~2020-05-11 17:10 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-11 13:54 [PATCH -next v2] locking/osq_lock: annotate a data race in osq_lock Qian Cai
2020-05-08 20:59 ` Qian Cai
2020-05-09  4:33   ` Paul E. McKenney
2020-05-09 13:01     ` Qian Cai
2020-05-09 16:12       ` Paul E. McKenney
2020-05-09 16:53         ` Qian Cai
2020-05-09 21:36           ` Paul E. McKenney
2020-05-11 15:58             ` Will Deacon
2020-05-11 16:43               ` Paul E. McKenney
2020-05-11 16:52                 ` Will Deacon
2020-05-11 17:29                   ` Paul E. McKenney
2020-05-11 17:34                     ` Will Deacon
2020-05-11 18:07                       ` Paul E. McKenney
2020-05-11 16:44               ` Qian Cai
2020-05-11 16:54                 ` Will Deacon
2020-05-11 17:10                   ` Qian Cai [this message]

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