Re: [PATCH 2/4] x86-64: Calgary IOMMU - move valid_dma_direction into the callers

Jeff Garzik
2006-05-25T04:35:19Z

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