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

[Logan Gunthorpe]

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
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