Message-Id: <200603281853.k2SIrGg28290@unix-os.sc.intel.com>
From: "Chen, Kenneth W" <kenneth.w.chen@intel.com>
To: "'Nick Piggin'" <nickpiggin@yahoo.com.au>,
       "Christoph Lameter" <clameter@sgi.com>
Cc: <akpm@osdl.org>, <Zoltan.Menyhart@free.fr>, <linux-kernel@vger.kernel.org>,
       <linux-ia64@vger.kernel.org>
Subject: RE: Fix unlock_buffer() to work the same way as bit_unlock()
Date: Tue, 28 Mar 2006 10:53:52 -0800
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Nick Piggin wrote on Tuesday, March 28, 2006 12:11 AM
> Also, I think there is still the issue of ia64 not having the
> correct memory consistency semantics. To start with, all the bitops
> and atomic ops which both modify their operand and return a value
> should be full memory barriers before and after the operation,
> according to Documentation/atomic_ops.txt.


I suppose the usage of atomic ops is abused, it is used in both lock
and unlock path.  And it naturally suck because it now requires full
memory barrier.  A better way is to define 3 variants: one for lock
path, one for unlock path, and one with full memory fence.

- Ken
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