[PATCH v2 05/21] alpha: return error code from alpha_pci_map_sg()

[Logan Gunthorpe <logang-OTvnGxWRz7hWk0Htik3J/w@public.gmane.org>]

From: Martin Oliveira <martin.oliveira-N4T0u6BTIXMybS5Ee8rs3A@public.gmane.org>

The .map_sg() op now expects an error code instead of zero on failure.

pci_map_single_1() can fail for different reasons, but since the only
supported type of error return is DMA_MAPPING_ERROR, we coalesce those
errors into EIO.

ENOMEM is returned when no page tables can be allocated.

Signed-off-by: Martin Oliveira <martin.oliveira-N4T0u6BTIXMybS5Ee8rs3A@public.gmane.org>
Signed-off-by: Logan Gunthorpe <logang-OTvnGxWRz7hWk0Htik3J/w@public.gmane.org>
Cc: Richard Henderson <rth-hL46jP5Bxq7R7s880joybQ@public.gmane.org>
Cc: Ivan Kokshaysky <ink-biIs/Y0ymYJMZLIVYojuPNP0rXTJTi09@public.gmane.org>
Cc: Matt Turner <mattst88-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
 arch/alpha/kernel/pci_iommu.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/arch/alpha/kernel/pci_iommu.c b/arch/alpha/kernel/pci_iommu.c
index 35d7b3096d6e..21f9ac101324 100644
--- a/arch/alpha/kernel/pci_iommu.c
+++ b/arch/alpha/kernel/pci_iommu.c
@@ -649,7 +649,9 @@ static int alpha_pci_map_sg(struct device *dev, struct scatterlist *sg,
 		sg->dma_address
 		  = pci_map_single_1(pdev, SG_ENT_VIRT_ADDRESS(sg),
 				     sg->length, dac_allowed);
-		return sg->dma_address != DMA_MAPPING_ERROR;
+		if (sg->dma_address == DMA_MAPPING_ERROR)
+			return -EIO;
+		return 1;
 	}
 
 	start = sg;
@@ -685,8 +687,10 @@ static int alpha_pci_map_sg(struct device *dev, struct scatterlist *sg,
 	if (out < end)
 		out->dma_length = 0;
 
-	if (out - start == 0)
+	if (out - start == 0) {
 		printk(KERN_WARNING "pci_map_sg failed: no entries?\n");
+		return -ENOMEM;
+	}
 	DBGA("pci_map_sg: %ld entries\n", out - start);
 
 	return out - start;
@@ -699,7 +703,7 @@ static int alpha_pci_map_sg(struct device *dev, struct scatterlist *sg,
 	   entries.  Unmap them now.  */
 	if (out > start)
 		pci_unmap_sg(pdev, start, out - start, dir);
-	return 0;
+	return -ENOMEM;
 }
 
 /* Unmap a set of streaming mode DMA translations.  Again, cpu read
-- 
2.20.1