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Subject[net-next PATCH 02/27] swiotlb-xen: Enforce return of DMA_ERROR_CODE in mapping function
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The mapping function should always return DMA_ERROR_CODE when a mapping has
failed as this is what the DMA API expects when a DMA error has occurred.
The current function for mapping a page in Xen was returning either
DMA_ERROR_CODE or 0 depending on where it failed.

On x86 DMA_ERROR_CODE is 0, but on other architectures such as ARM it is
~0. We need to make sure we return the same error value if either the
mapping failed or the device is not capable of accessing the mapping.

If we are returning DMA_ERROR_CODE as our error value we can drop the
function for checking the error code as the default is to compare the
return value against DMA_ERROR_CODE if no function is defined.

Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
---
arch/arm/xen/mm.c | 1 -
arch/x86/xen/pci-swiotlb-xen.c | 1 -
drivers/xen/swiotlb-xen.c | 18 ++++++------------
include/xen/swiotlb-xen.h | 3 ---
4 files changed, 6 insertions(+), 17 deletions(-)

diff --git a/arch/arm/xen/mm.c b/arch/arm/xen/mm.c
index d062f08..bd62d94 100644
--- a/arch/arm/xen/mm.c
+++ b/arch/arm/xen/mm.c
@@ -186,7 +186,6 @@ void xen_destroy_contiguous_region(phys_addr_t pstart, unsigned int order)
EXPORT_SYMBOL(xen_dma_ops);

static struct dma_map_ops xen_swiotlb_dma_ops = {
- .mapping_error = xen_swiotlb_dma_mapping_error,
.alloc = xen_swiotlb_alloc_coherent,
.free = xen_swiotlb_free_coherent,
.sync_single_for_cpu = xen_swiotlb_sync_single_for_cpu,
diff --git a/arch/x86/xen/pci-swiotlb-xen.c b/arch/x86/xen/pci-swiotlb-xen.c
index 0e98e5d..a9fafb5 100644
--- a/arch/x86/xen/pci-swiotlb-xen.c
+++ b/arch/x86/xen/pci-swiotlb-xen.c
@@ -19,7 +19,6 @@
int xen_swiotlb __read_mostly;

static struct dma_map_ops xen_swiotlb_dma_ops = {
- .mapping_error = xen_swiotlb_dma_mapping_error,
.alloc = xen_swiotlb_alloc_coherent,
.free = xen_swiotlb_free_coherent,
.sync_single_for_cpu = xen_swiotlb_sync_single_for_cpu,
diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index 87e6035..b8014bf 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -416,11 +416,12 @@ dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page,
/*
* Ensure that the address returned is DMA'ble
*/
- if (!dma_capable(dev, dev_addr, size)) {
- swiotlb_tbl_unmap_single(dev, map, size, dir);
- dev_addr = 0;
- }
- return dev_addr;
+ if (dma_capable(dev, dev_addr, size))
+ return dev_addr;
+
+ swiotlb_tbl_unmap_single(dev, map, size, dir);
+
+ return DMA_ERROR_CODE;
}
EXPORT_SYMBOL_GPL(xen_swiotlb_map_page);

@@ -648,13 +649,6 @@ void xen_swiotlb_unmap_page(struct device *hwdev, dma_addr_t dev_addr,
}
EXPORT_SYMBOL_GPL(xen_swiotlb_sync_sg_for_device);

-int
-xen_swiotlb_dma_mapping_error(struct device *hwdev, dma_addr_t dma_addr)
-{
- return !dma_addr;
-}
-EXPORT_SYMBOL_GPL(xen_swiotlb_dma_mapping_error);
-
/*
* Return whether the given device DMA address mask can be supported
* properly. For example, if your device can only drive the low 24-bits
diff --git a/include/xen/swiotlb-xen.h b/include/xen/swiotlb-xen.h
index 7c35e27..a0083be 100644
--- a/include/xen/swiotlb-xen.h
+++ b/include/xen/swiotlb-xen.h
@@ -51,9 +51,6 @@ extern void xen_swiotlb_unmap_page(struct device *hwdev, dma_addr_t dev_addr,
int nelems, enum dma_data_direction dir);

extern int
-xen_swiotlb_dma_mapping_error(struct device *hwdev, dma_addr_t dma_addr);
-
-extern int
xen_swiotlb_dma_supported(struct device *hwdev, u64 mask);

extern int
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