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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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      Last update: 2016-10-25 23:39    [W:4.406 / U:0.012 seconds]
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