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From: Byungchul Park <max.byungchul.park@gmail.com>
Date: Thu, 7 Sep 2017 20:37:08 +0900
Message-ID: <CANrsvROa_ppmezwL9Se+jUVy_Yie+TMjP-s85Y==a9Ku4mqDYA@mail.gmail.com>
Subject: Re: [PATCH] lockdep: Remove unnecessary acquisitions wrt workqueue flush
To: Peter Zijlstra <peterz@infradead.org>
Cc: Byungchul Park <byungchul.park@lge.com>, Tejun Heo <tj@kernel.org>,
        johannes.berg@intel.com, Ingo Molnar <mingo@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>, oleg@redhat.com,
        david@fromorbit.com,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        kernel-team@lge.com
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On Thu, Sep 7, 2017 at 6:41 PM, Peter Zijlstra <peterz@infradead.org> wrote:
> On Thu, Sep 07, 2017 at 09:33:16AM +0900, Byungchul Park wrote:
>> Workqueue added manual acquisitions to catch deadlock cases. Now
>> crossrelease was introduced, some of those are redundant because
>> crossrelease-enabled wait_for_completeion() also does it. Removed it.
>
> This does not explain how it doesn't become the regular timing dependent
> stuff cross-release normally is.

Yes, I will add more explanation for it at the next spin.

But, let me explain it a bit here to help you get it, since it's very
simple. This has nothing to do with 'might' thing I introduced
previously. For 'might' thing, I will start it after getting your response.

Here, I just removed acquire() because wait_for_completion()
already includes the acquire() by LOCKDEP_COMPLETIONS.
That's all.

-- 
Thanks,
Byungchul