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Date: Fri, 4 Oct 2013 21:41:26 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
        Mel Gorman <mgorman@suse.de>, Rik van Riel <riel@redhat.com>,
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        Ingo Molnar <mingo@kernel.org>, Andrea Arcangeli <aarcange@redhat.com>,
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        Steven Rostedt <rostedt@goodmis.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/3] rcu: Create rcu_sync infrastructure
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On Fri, Oct 04, 2013 at 09:06:53PM +0200, Oleg Nesterov wrote:
> However, yes-yes-yes, I do think that we need the non-exclusive mode
> too, at least for percpu_down_write_nonexclusive() which I think we
> need as well.

I just need to disagree with the write_nonexclusive() name; the
construct I quite understand and could even agree with.

How about something like:

State excluding 'writers', but not itself:
	percpu_read_lock()
	percpu_read_unlock()

State excluding readers, but not itself:
	percpu_non_read_lock();
	percpu_non_read_unlock();

Full exclusive state:
	percpu_write_lock();
	percpu_write_unlock();

At which point I start to have doubts about the percpu prefix.. ;-)