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Subject: Re: [PATCH 2/2] scsi: Use new __dma_buffer to align sense buffer
	in scsi_cmnd
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Reply-To: benh@kernel.crashing.org
To: Matthew Wilcox <matthew@wil.cx>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>, linux-kernel@vger.kernel.org,
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Date: Sat, 22 Dec 2007 08:29:07 +1100
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On Fri, 2007-12-21 at 06:16 -0700, Matthew Wilcox wrote:
> On Fri, Dec 21, 2007 at 10:33:26AM +0000, Alan Cox wrote:
> > On Fri, 21 Dec 2007 13:30:08 +1100
> > Benjamin Herrenschmidt <benh@kernel.crashing.org> wrote:
> > 
> > > The sense buffer ins scsi_cmnd can nowadays be DMA'ed into directly
> > > by some low level drivers (that typically happens with USB mass
> > > storage).
> > 
> > Should that not be fixed in USB storage by using pci_alloc_coherent on the
> > PCI device of the hub not peeing directly into kernel space ?
> 
> That's what I said, but Ben seems fixated on this particular fix.

That means more understanding of the SCSI code than I have right now
and a _lot_ more time than I have right now. It's not only USB storage,
it's anything that does DMA and uses the generic error handling.

Ben.