Re: [PATCH] ipc/msg: Implement lockless pipelined wakeups

From	Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Newsgroups	linux.kernel
Subject	Re: [PATCH] ipc/msg: Implement lockless pipelined wakeups
Date	2015-11-03 15:20 +0100
Message-ID	<qqKBj-3MG-3@gated-at.bofh.it> (permalink)
References	<qpBJM-1GA-5@gated-at.bofh.it> <qpE4W-3dY-1@gated-at.bofh.it> <qpJxE-6qG-11@gated-at.bofh.it> <qpJHj-6JK-1@gated-at.bofh.it>
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On 10/31/2015 08:06 PM, Davidlohr Bueso wrote:
> On Sat, 31 Oct 2015, Bueso wrote:
> 
>> Yes, and this confirms that we still rely on the implicit barrier
>> from the cmpxchg as tglx mentioned. As such, we also need to keep
>> the pairing when reading 'r_msg' in do_msgrcv(), instead of dropping
>> the comments.
> 
> Hmm having r_msg as volatile seems even less needed now, we should
> drop it. I imagine it was there initially for the busy-wait on the variable
> becoming non-nil, but we had cpu_relax _anyway_, so ...

Didn't noticed that. So that volatile part and the casts are gone, too.

Sebastian
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Thread

Re: [PATCH] ipc/msg: Implement lockless pipelined wakeups Davidlohr Bueso <dave@stgolabs.net> - 2015-10-31 20:00 +0100
  Re: [PATCH] ipc/msg: Implement lockless pipelined wakeups Davidlohr Bueso <dave@stgolabs.net> - 2015-10-31 20:10 +0100
    Re: [PATCH] ipc/msg: Implement lockless pipelined wakeups Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2015-11-03 15:20 +0100
  Re: [PATCH] ipc/msg: Implement lockless pipelined wakeups Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2015-11-03 15:20 +0100

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