Re: [RFC PATCH v2 07/11] dma-mapping: Add flags to dma_map_ops to indicate PCI P2PDMA support

Logan Gunthorpe
2021-03-15T16:33:27Z

On 2021-03-12 7:36 p.m., Ira Weiny wrote:
> On Thu, Mar 11, 2021 at 04:31:37PM -0700, Logan Gunthorpe wrote:
>
>> +int dma_pci_p2pdma_supported(struct device *dev)
> ^^^
> bool?

Sure.

>
>> +{
>> + const struct dma_map_ops *ops = get_dma_ops(dev);
>> +
>> + return !ops || ops->flags & DMA_F_PCI_P2PDMA_SUPPORTED;
>
> Is this logic correct? I would have expected.
>
> return (ops && ops->flags & DMA_F_PCI_P2PDMA_SUPPORTED);

If ops is NULL then the operations in kernel/dma/direct.c are used and
support is added to those in patch 6. So it is correct as written.

Logan