From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Davidlohr Bueso <dave@stgolabs.net>, George Spelvin <linux@horizon.com>
Cc: tglx@linutronix.de, akpm@linux-foundation.org,
linux-kernel@vger.kernel.org, manfred@colorfullife.com,
peterz@infradead.org
Subject: Re: [PATCH] ipc/msg: Implement lockless pipelined wakeups
Date: Tue, 3 Nov 2015 15:11:37 +0100 [thread overview]
Message-ID: <5638C099.3040706@linutronix.de> (raw)
In-Reply-To: <20151031185457.GC7947@linux-uzut.site>
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
next prev parent reply other threads:[~2015-11-03 14:11 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-30 11:26 [PATCH] ipc/msg: Implement lockless pipelined wakeups Sebastian Andrzej Siewior
2015-10-30 22:30 ` George Spelvin
2015-11-03 14:01 ` Sebastian Andrzej Siewior
2015-10-31 10:31 ` Thomas Gleixner
2015-10-31 13:02 ` George Spelvin
2015-10-31 15:17 ` Thomas Gleixner
2015-10-31 18:54 ` Davidlohr Bueso
2015-10-31 19:06 ` Davidlohr Bueso
2015-11-03 14:15 ` Sebastian Andrzej Siewior
2015-11-03 14:11 ` Sebastian Andrzej Siewior [this message]
2015-11-01 4:32 ` Manfred Spraul
2015-11-03 14:51 ` Sebastian Andrzej Siewior
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