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-1@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>
Organization	linux.* mail to news gateway

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On 10/31/2015 07:54 PM, Davidlohr Bueso wrote:
>> However, a wake_q keeps a reference to a task, so exiting is
>> not a danger.  As long as wake_q_add precedes setting r_msg,
>> all is well.
> 
> 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.

Okay, I took the memory-barrier comment from your mqueue patch and
adjusted.

> 
> Thanks,
> Davidlohr

Sebastian
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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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