Re: [PATCH 13/16] nvme-pci: Convert to using dma_map_sg_p2pdma for p2pdma pages

[Logan Gunthorpe]

On 2021-05-02 7:34 p.m., John Hubbard wrote:
>>   	if (iod->npages == 0)
>>   		dma_pool_free(dev->prp_small_pool, nvme_pci_iod_list(req)[0],
>>   			      iod->first_dma);
>> @@ -868,14 +857,13 @@ static blk_status_t nvme_map_data(struct nvme_dev *dev, struct request *req,
>>   	if (!iod->nents)
>>   		goto out_free_sg;
>>   
>> -	if (is_pci_p2pdma_page(sg_page(iod->sg)))
>> -		nr_mapped = pci_p2pdma_map_sg_attrs(dev->dev, iod->sg,
>> -				iod->nents, rq_dma_dir(req), DMA_ATTR_NO_WARN);
>> -	else
>> -		nr_mapped = dma_map_sg_attrs(dev->dev, iod->sg, iod->nents,
>> -					     rq_dma_dir(req), DMA_ATTR_NO_WARN);
>> -	if (!nr_mapped)
>> +	nr_mapped = dma_map_sg_p2pdma_attrs(dev->dev, iod->sg, iod->nents,
>> +				     rq_dma_dir(req), DMA_ATTR_NO_WARN);
>> +	if (nr_mapped < 0) {
>> +		if (nr_mapped != -ENOMEM)
>> +			ret = BLK_STS_TARGET;
>>   		goto out_free_sg;
>> +	}
> 
> But now the "nr_mapped == 0" case is no longer doing an early out_free_sg.
> Is that OK?

dma_map_sg_p2pdma_attrs() never returns zero. It will return -ENOMEM in
the same situation and results in the same goto out_free_sg.

Logan