Re: [PATCH] lockdep: Remove unnecessary acquisitions wrt workqueue flush

From	Peter Zijlstra <peterz@infradead.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH] lockdep: Remove unnecessary acquisitions wrt workqueue flush
Date	2017-09-07 17:30 +0200
Message-ID	<un6UH-1Tf-31@gated-at.bofh.it> (permalink)
References	<umT1n-KQ-9@gated-at.bofh.it> <un1BE-6At-17@gated-at.bofh.it> <un3k5-7L9-7@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Thu, Sep 07, 2017 at 08:37:08PM +0900, Byungchul Park wrote:
> 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.

Ah I see, but it does so using some fairly nasty completion init stuff.
The old code was far easier to read.

Thread

[PATCH] lockdep: Remove unnecessary acquisitions wrt workqueue flush Byungchul Park <byungchul.park@lge.com> - 2017-09-07 02:40 +0200
  Re: [PATCH] lockdep: Remove unnecessary acquisitions wrt workqueue  flush Peter Zijlstra <peterz@infradead.org> - 2017-09-07 11:50 +0200
    Re: [PATCH] lockdep: Remove unnecessary acquisitions wrt workqueue flush Byungchul Park <max.byungchul.park@gmail.com> - 2017-09-07 13:40 +0200
      Re: [PATCH] lockdep: Remove unnecessary acquisitions wrt workqueue  flush Peter Zijlstra <peterz@infradead.org> - 2017-09-07 17:30 +0200
        Re: [PATCH] lockdep: Remove unnecessary acquisitions wrt workqueue flush Byungchul Park <max.byungchul.park@gmail.com> - 2017-09-07 23:30 +0200

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