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Date: Sat, 31 Oct 2015 12:06:33 -0700
From: Davidlohr Bueso <dave@stgolabs.net>
To: George Spelvin <linux@horizon.com>
Cc: bigeasy@linutronix.de, 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
Message-ID: <20151031190633.GA1707@linux-uzut.site>
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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 ...