Re: [PATCH v4 03/23] PCI/P2PDMA: Attempt to set map_type if it has not been set

[Chaitanya Kulkarni]

On 11/17/21 1:53 PM, Logan Gunthorpe wrote:
> Attempt to find the mapping type for P2PDMA pages on the first
> DMA map attempt if it has not been done ahead of time.
> 
> Previously, the mapping type was expected to be calculated ahead of
> time, but if pages are to come from userspace then there's no
> way to ensure the path was checked ahead of time.
> 
> This change will calculate the mapping type if it hasn't pre-calculated
> so it is no longer invalid to call pci_p2pdma_map_sg() before the mapping
> type is calculated, so drop the WARN_ON when that is he case.
> 
> Signed-off-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>
> Acked-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> ---

Perhaps a comment would be nice in the default case in
pci_p2pdma_map_sg_attrs() where you have removed the WARN_ON_ONCE().

Either way, looks good.

Reviewed-by: Chaitanya Kulkarni <kch@xxxxxxxxxx>