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DateThu, 25 May 2006 00:35:07 -0400
FromJeff Garzik <>
SubjectRe: [PATCH 2/4] x86-64: Calgary IOMMU - move valid_dma_direction into the callers
Jon Mason wrote:
>>From Andi Kleen's comments on the original Calgary patch, move
> valid_dma_direction into the calling functions.
> 
> Signed-off-by: Muli Ben-Yehuda <muli@il.ibm.com>
> Signed-off-by: Jon Mason <jdmason@us.ibm.com>

Even though BUG_ON() includes unlikely(), this introduces additional 
tests in very hot paths.

_Why_ do we need this at all?

I would prefer to NAK the patch, and fix the odd user that gets it 
wrong.  It becomes REALLY obvious that a driver has gotten this wrong, 
REALLY quickly.

I see no need to burden critical hot paths with dumb checks like this.

	Jeff



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