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To: "Michael S. Tsirkin" <mst@mellanox.co.il>
Cc: akpm@osdl.org, linux-kernel@vger.kernel.org, openib-general@openib.org
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	<20050113094532.GA31298@mellanox.co.il>
From: Roland Dreier <roland@topspin.com>
Date: Thu, 13 Jan 2005 07:32:15 -0800
In-Reply-To: <20050113094532.GA31298@mellanox.co.il> (Michael S. Tsirkin's
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    Michael> Since we are using the eqe here, it seems that
    Michael> read_barrier_depends shall be sufficient (as well as in
    Michael> the cq case)?

    Michael> However, I see that read_barrier_depends is a nop on ppc,
    Michael> and the comment indicates that problems were seen on ppc
    Michael> 970.  What gives? do I misunderstand what a dependency
    Michael> is?

There is no dependency between the EQE ownership field and the rest of
the EQE, so read_barrier_depends() is not sufficient.  I think you are
misunderstanding what a dependency is.  The comments in
asm-i386/system.h or http://lse.sourceforge.net/locking/wmbdd.html may
help clear things up.

 - R.
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