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

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