Re: [PATCH 09/16] dma-direct: Support PCI P2PDMA pages in dma-direct map_sg

John Hubbard
2021-05-02T23:32:55Z

On 5/2/21 4:28 PM, John Hubbard wrote:
> On 4/8/21 10:01 AM, Logan Gunthorpe wrote:
...
>> @@ -387,19 +388,37 @@ void dma_direct_unmap_sg(struct device *dev, struct scatterlist *sgl,
>
> This routine now deserves a little bit of commenting, now that it is
> doing less obvious things. How about something like this:
>
> /*
> * Unmaps pages, except for PCI_P2PDMA pages, which were never mapped in the
> * first place. Instead of unmapping PCI_P2PDMA entries, simply remove the
> * SG_PCI_P2PDMA mark
> */

I got that kind of wrong. They *were* mapped, but need to be left mostly
alone...maybe you can word it better. Here's my second draft:

/*
* Unmaps pages, except for PCI_P2PDMA pages, which should not be unmapped at
* this point. Instead of unmapping PCI_P2PDMA entries, simply remove the
* SG_PCI_P2PDMA mark.
*/

...am I getting close? :)

thanks,
--
John Hubbard
NVIDIA