# Re: \[PATCH v1 16/16\] dma-mapping: Disallow .map\_sg operations from returning zero on error

- From: Logan Gunthorpe \<logang@deltatee.com\>
- Date: 2021-07-16 16:18:16 
- List: linux-arm-kernel
- Page: https://ratatoskr.run/linux-arm-kernel/2021/07/1447698
- Thread: https://ratatoskr.run/linux-alpha/2021/07/1445836/t.md

```text


On 2021-07-16 12:33 a.m., Christoph Hellwig wrote:
> On Thu, Jul 15, 2021 at 10:45:44AM -0600, Logan Gunthorpe wrote:
>> @@ -194,6 +194,8 @@ static int __dma_map_sg_attrs(struct device *dev, struct scatterlist *sg,
>>  	else
>>  		ents = ops->map_sg(dev, sg, nents, dir, attrs);
>>  
>> +	WARN_ON_ONCE(ents == 0);
> 
> Turns this into a negative error code while we're at it, just to keep
> the callers sane?
> 

Sure thing. All the feedback makes sense, we'll fix it up and send a v2
in due course.

Thanks,

Logan

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