Re: [PATCH v1 04/16] dma-iommu: Return error code from iommu_dma_map_sg()

[Christoph Hellwig]

Careful here. What do all these errors from the low-level code mean
here?  I think we need to clearly standardize on what we actually
return from ->map_sg and possibly document what the callers expect and
can do, and enforce that only those error are reported.

[PATCH v1 04/16] dma-iommu: Return error code from iommu_dma_map_sg()

[Logan Gunthorpe]

Pass through appropriate error codes from iommu_dma_map_sg() now that
the error code will be passed through dma_map_sgtable().

Signed-off-by: Logan Gunthorpe 
Cc: Joerg Roedel 
Cc: Will Deacon 
---
 drivers/iommu/dma-iommu.c | 20 +---
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 98ba927aee1a..9d35e9994306 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -972,7 +972,7 @@ static int iommu_dma_map_sg_swiotlb(struct device *dev, 
struct scatterlist *sg,
 
 out_unmap:
iommu_dma_unmap_sg_swiotlb(dev, sg, i, dir, attrs | 
DMA_ATTR_SKIP_CPU_SYNC);
-   return 0;
+   return -EINVAL;
 }
 
 /*
@@ -993,11 +993,14 @@ static int iommu_dma_map_sg(struct device *dev, struct 
scatterlist *sg,
dma_addr_t iova;
size_t iova_len = 0;
unsigned long mask = dma_get_seg_boundary(dev);
+   ssize_t ret;
int i;
 
-   if (static_branch_unlikely(_deferred_attach_enabled) &&
-   iommu_deferred_attach(dev, domain))
-   return 0;
+   if (static_branch_unlikely(_deferred_attach_enabled)) {
+   ret = iommu_deferred_attach(dev, domain);
+   if (ret)
+   return ret;
+   }
 
if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
iommu_dma_sync_sg_for_device(dev, sg, nents, dir);
@@ -1045,14 +1048,17 @@ static int iommu_dma_map_sg(struct device *dev, struct 
scatterlist *sg,
}
 
iova = iommu_dma_alloc_iova(domain, iova_len, dma_get_mask(dev), dev);
-   if (!iova)
+   if (!iova) {
+   ret = -ENOMEM;
goto out_restore_sg;
+   }
 
/*
 * We'll leave any physical concatenation to the IOMMU driver's
 * implementation - it knows better than we do.
 */
-   if (iommu_map_sg_atomic(domain, iova, sg, nents, prot) < iova_len)
+   ret = iommu_map_sg_atomic(domain, iova, sg, nents, prot);
+   if (ret < iova_len)
goto out_free_iova;
 
return __finalise_sg(dev, sg, nents, iova);
@@ -1061,7 +1067,7 @@ static int iommu_dma_map_sg(struct device *dev, struct 
scatterlist *sg,
iommu_dma_free_iova(cookie, iova, iova_len, NULL);
 out_restore_sg:
__invalidate_sg(sg, nents);
-   return 0;
+   return ret;
 }
 
 static void iommu_dma_unmap_sg(struct device *dev, struct scatterlist *sg,
-- 
2.20.1