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swiotlb-xen: Enforce return of DMA_ERROR_CODE in mapping function 

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>
Signed-off-by: Konrad Rzeszutek Wilk <konrad@kernel.org>
This commit is contained in:
Alexander Duyck 2016-11-02 07:12:47 -04:00 committed by Konrad Rzeszutek Wilk
parent ebcf6f979d
commit 7641842164
4 changed files with 6 additions and 17 deletions
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1
arch/arm/xen/mm.c
View File

@ -186,7 +186,6 @@ struct dma_map_ops *xen_dma_ops;
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,

1
arch/x86/xen/pci-swiotlb-xen.c
View File

@ -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,

18
drivers/xen/swiotlb-xen.c
View File

@ -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 @@ xen_swiotlb_sync_sg_for_device(struct device *hwdev, struct scatterlist *sg,
}
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

3
include/xen/swiotlb-xen.h
View File

@ -50,9 +50,6 @@ extern void
xen_swiotlb_sync_sg_for_device(struct device *hwdev, struct scatterlist *sg,
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);