David S. Miller wrote:

From: Nick Piggin <redacted>
Subject: Re: [patch 2] mm: speculative get_page
Date: Tue, 28 Jun 2005 14:50:31 +1000

quoted

William Lee Irwin III wrote:

quoted

On Tue, Jun 28, 2005 at 11:42:16AM +1000, Nick Piggin wrote:

spin_unlock() does not imply a memory barrier.

Intriguing...

BTW, I disagree with this assertion.  spin_unlock() does imply a
memory barrier.

All memory operations before the release of the lock must execute
before the lock release memory operation is globally visible.

Yes, it appears that way from looking at a sample set of arch
code too (ie. those without strictly ordered stores put an
explicit barrier there).

I've always understood spin_unlock to imply a barrier.


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