linux-kernel - Re: [PATCH v1 14/16] x86/amd_gart: return error code from gart_map

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Date:   Fri, 16 Jul 2021 13:11:33 +0100
From:   Robin Murphy <robin.murphy@....com>
To:     Christoph Hellwig <hch@....de>,
        Logan Gunthorpe <logang@...tatee.com>
Cc:     linux-kernel@...r.kernel.org, linux-alpha@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-ia64@...r.kernel.org,
        linux-mips@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-s390@...r.kernel.org, sparclinux@...r.kernel.org,
        iommu@...ts.linux-foundation.org, linux-parisc@...r.kernel.org,
        xen-devel@...ts.xenproject.org,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Stephen Bates <sbates@...thlin.com>,
        Martin Oliveira <martin.oliveira@...eticom.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Niklas Schnelle <schnelle@...ux.ibm.com>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Michael Ellerman <mpe@...erman.id.au>
Subject: Re: [PATCH v1 14/16] x86/amd_gart: return error code from
 gart_map_sg()

On 2021-07-16 07:32, Christoph Hellwig wrote:
> On Thu, Jul 15, 2021 at 10:45:42AM -0600, Logan Gunthorpe wrote:
>> @@ -458,7 +460,7 @@ static int gart_map_sg(struct device *dev, struct scatterlist *sg, int nents,
>>   	iommu_full(dev, pages << PAGE_SHIFT, dir);
>>   	for_each_sg(sg, s, nents, i)
>>   		s->dma_address = DMA_MAPPING_ERROR;
>> -	return 0;
>> +	return ret;
> 
> While we're at it - setting the ->dma_address to DMA_MAPPING_ERROR is
> not part of the ->map_sg calling convention.  Might be worth to fix
> up while we're at it.

Especially since it's not even zeroing dma_length, which at least is a 
documented indicator of validity (even if it's not strictly defined for 
failure cases either).

Robin.