To: Christoph Hellwig <hch@infradead.org>
Cc: akepner@sgi.com, Tony Luck <tony.luck@intel.com>,
       Grant Grundler <grundler@parisc-linux.org>,
       Jesse Barnes <jbarnes@virtuousgeek.org>, Jes Sorensen <jes@sgi.com>,
       Randy Dunlap <randy.dunlap@oracle.com>,
       James Bottomley <James.Bottomley@steeleye.com>,
       David Miller <davem@davemloft.net>, Muli Ben-Yehuda <muli@il.ibm.com>,
       linux-kernel@vger.kernel.org
Subject: Re: [RFC/PARTIAL PATCH 0/3] dma: passing "attributes" to dma_map_* routines
References: <20080108023222.GP23661@sgi.com>
	<20080108175054.GA25168@infradead.org>
From: Roland Dreier <rdreier@cisco.com>
Date: Tue, 08 Jan 2008 09:55:24 -0800
In-Reply-To: <20080108175054.GA25168@infradead.org> (Christoph Hellwig's message of "Tue, 8 Jan 2008 17:50:54 +0000")
Message-ID: <ada1w8skxrn.fsf@cisco.com>
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 > Onething I've missed with these patches is drivers actually using
 > it.  What driver actually needs it and why don't you send patches
 > for them?

In previous patch series, Arthur sent fixes for the mthca IB driver.
Other IB drivers like mlx4 also need this on Altix systems.  Basically
anything where the device DMAs some data into userspace and then DMAs
a "completed" status to another buffer in userspace leads to a problem
where the "completed" DMA might pass the actual data in the Altix
fabric, which leads to the userspace process working with bogus data.

 - R.

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