Re: [PATCH] lockdep: Add a document describing crossrelease feature

From	Byungchul Park <byungchul.park@lge.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH] lockdep: Add a document describing crossrelease feature
Date	2016-07-06 07:40 +0200
Message-ID	<rRNIZ-563-1@gated-at.bofh.it> (permalink)
References	(1 earlier) <rPY5P-1V8-1@gated-at.bofh.it> <rQ4bf-5yT-3@gated-at.bofh.it> <rR5RE-2gx-9@gated-at.bofh.it> <rRJcl-1UL-5@gated-at.bofh.it> <rRKBr-38O-11@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Wed, Jul 06, 2016 at 11:17:10AM +0900, Byungchul Park wrote:
> 
> lock(A)
> wait_for(B)
> ~~~~~~~~~~~~~~~~~~~~~~~~ <- serialized by atomic operation
> 		lock(A)
> 		unlock(A)
> 		wake(B)
> unlock(A)

By the way, I have a question. Is there anyone who could answer it?

I want to serialize between two context's lock operations, for example,

	context A	context B
	--------------	--------------
	lock A
	lock B		...
	lock C
	atomic_inc_return
	~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ <- serialization
			atomic_read
			lock D
	...		lock E
			lock F

so that we can see these in the order like A -> B -> C -> D -> E -> F.

atomic_inc_return() is used after lock C in context A, and atomic_read()
is used before lock D in context B. And I want to make it serialized when
the atomic_read() can see the increased value.

Can I use smp_mb__after_atomic() just after atomic_read() or should I use
smp_mb()? I think anyway I have to choose one of them for that ordering.

Thank you,
Byungchul

Thread

[PATCH] lockdep: Add a document describing crossrelease feature Byungchul Park <byungchul.park@lge.com> - 2016-07-01 06:20 +0200
  Re: [PATCH] lockdep: Add a document describing crossrelease feature Peter Zijlstra <peterz@infradead.org> - 2016-07-01 12:50 +0200
    Re: [PATCH] lockdep: Add a document describing crossrelease feature Byungchul Park <byungchul.park@lge.com> - 2016-07-04 08:50 +0200
      Re: [PATCH] lockdep: Add a document describing crossrelease feature Boqun Feng <boqun.feng@gmail.com> - 2016-07-06 02:50 +0200
        Re: [PATCH] lockdep: Add a document describing crossrelease feature Byungchul Park <byungchul.park@lge.com> - 2016-07-06 04:20 +0200
          Re: [PATCH] lockdep: Add a document describing crossrelease feature Byungchul Park <byungchul.park@lge.com> - 2016-07-06 07:40 +0200
            Re: [PATCH] lockdep: Add a document describing crossrelease feature Peter Zijlstra <peterz@infradead.org> - 2016-07-06 10:00 +0200
              Re: [PATCH] lockdep: Add a document describing crossrelease feature Byungchul Park <byungchul.park@lge.com> - 2016-07-06 10:20 +0200

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