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Date: Tue, 11 Jun 2013 10:35:53 -0700
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Subject: Re: [PATCH RFC ticketlock] v2 Auto-queued ticketlock
From: Linus Torvalds <torvalds@linux-foundation.org>
To: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
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Hmm. Something just struck me when reading this patch..

Our memory ordering semantics in our *current* locks are very very
subtle. We have just a "barrier()" between the

    inc.head = ACCESS_ONCE(lock->tickets.head);
    if (inc.head == inc.tail)
        break; /* success */

and the inside of the locked region.

I think it's safe because of the new memory ordering semantics (loads
are in-order, and stores only move *down*), but there's not even a
comment about it.

So let's at least comment the current locks before making them even
more complex and subtle..

              Linus
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