Re: [PATCH v1 10/16] s390/pci: return error code from s390_dma_map_sg()

Niklas Schnelle
2021-07-16T08:24:08Z

On Thu, 2021-07-15 at 10:45 -0600, Logan Gunthorpe wrote:
> From: Martin Oliveira <martin.oliveira@eideticom.com>
>
> The .map_sg() op now expects an error code instead of zero on failure.
>
> So propagate the error from __s390_dma_map_sg() up.
>
> Signed-off-by: Martin Oliveira <martin.oliveira@eideticom.com>
> Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
> Cc: Niklas Schnelle <schnelle@linux.ibm.com>
> Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
> Cc: Heiko Carstens <hca@linux.ibm.com>
> Cc: Vasily Gorbik <gor@linux.ibm.com>
> Cc: Christian Borntraeger <borntraeger@de.ibm.com>
> ---
> arch/s390/pci/pci_dma.c | 12 +++++++-----
> 1 file changed, 7 insertions(+), 5 deletions(-)
>
> diff --git a/arch/s390/pci/pci_dma.c b/arch/s390/pci/pci_dma.c
> index ebc9a49523aa..c78b02012764 100644
> --- a/arch/s390/pci/pci_dma.c
> +++ b/arch/s390/pci/pci_dma.c
> @@ -487,7 +487,7 @@ static int s390_dma_map_sg(struct device *dev, struct scatterlist *sg,
> unsigned int max = dma_get_max_seg_size(dev);
> unsigned int size = s->offset + s->length;
> unsigned int offset = s->offset;
> - int count = 0, i;
> + int count = 0, i, ret;
>
> for (i = 1; i < nr_elements; i++) {
> s = sg_next(s);
> @@ -497,8 +497,9 @@ static int s390_dma_map_sg(struct device *dev, struct scatterlist *sg,
>
> if (s->offset || (size & ~PAGE_MASK) ||
> size + s->length > max) {
> - if (__s390_dma_map_sg(dev, start, size,
> - &dma->dma_address, dir))
> + ret = __s390_dma_map_sg(dev, start, size,
> + &dma->dma_address, dir);
> + if (ret)
> goto unmap;
>
> dma->dma_address += offset;
> @@ -511,7 +512,8 @@ static int s390_dma_map_sg(struct device *dev, struct scatterlist *sg,
> }
> size += s->length;
> }
> - if (__s390_dma_map_sg(dev, start, size, &dma->dma_address, dir))
> + ret = __s390_dma_map_sg(dev, start, size, &dma->dma_address, dir);
> + if (ret)
> goto unmap;
>
> dma->dma_address += offset;
> @@ -523,7 +525,7 @@ static int s390_dma_map_sg(struct device *dev, struct scatterlist *sg,
> s390_dma_unmap_pages(dev, sg_dma_address(s), sg_dma_len(s),
> dir, attrs);
>
> - return 0;
> + return ret;
> }
>
> static void s390_dma_unmap_sg(struct device *dev, struct scatterlist *sg,

So the error codes we return are -ENOMEM if allocating a DMA
translation entry fails and -EINVAL if the DMA translation table hasn't
been initialized or the caller tries to map 0 sized memory. Are these
error codes that you would expect? If yes then this change looks good
to me.

Acked-by: Niklas Schnelle <schnelle@linux.ibm.com>