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    Subject[PATCH 49/67] swiotlb: refactor coherent buffer freeing
    Date
    Factor out a new swiotlb_free_buffer helper that checks if an address
    is allocated from the swiotlb bounce buffer, and if yes frees it.

    This allows to simplify the swiotlb_free implemenation that uses
    dma_direct_free to free the non-bounce buffer allocations.

    Signed-off-by: Christoph Hellwig <hch@lst.de>
    ---
    lib/swiotlb.c | 35 +++++++++++++++++++++--------------
    1 file changed, 21 insertions(+), 14 deletions(-)

    diff --git a/lib/swiotlb.c b/lib/swiotlb.c
    index a14fff30ee9d..adb4dd0091fa 100644
    --- a/lib/swiotlb.c
    +++ b/lib/swiotlb.c
    @@ -773,22 +773,31 @@ swiotlb_alloc_coherent(struct device *hwdev, size_t size,
    }
    EXPORT_SYMBOL(swiotlb_alloc_coherent);

    +static bool swiotlb_free_buffer(struct device *dev, size_t size,
    + dma_addr_t dma_addr)
    +{
    + phys_addr_t phys_addr = dma_to_phys(dev, dma_addr);
    +
    + WARN_ON_ONCE(irqs_disabled());
    +
    + if (!is_swiotlb_buffer(phys_addr))
    + return false;
    +
    + /*
    + * DMA_TO_DEVICE to avoid memcpy in swiotlb_tbl_unmap_single.
    + * DMA_ATTR_SKIP_CPU_SYNC is optional.
    + */
    + swiotlb_tbl_unmap_single(dev, phys_addr, size, DMA_TO_DEVICE,
    + DMA_ATTR_SKIP_CPU_SYNC);
    + return true;
    +}
    +
    void
    swiotlb_free_coherent(struct device *hwdev, size_t size, void *vaddr,
    dma_addr_t dev_addr)
    {
    - phys_addr_t paddr = dma_to_phys(hwdev, dev_addr);
    -
    - WARN_ON(irqs_disabled());
    - if (!is_swiotlb_buffer(paddr))
    + if (!swiotlb_free_buffer(hwdev, size, dev_addr))
    free_pages((unsigned long)vaddr, get_order(size));
    - else
    - /*
    - * DMA_TO_DEVICE to avoid memcpy in swiotlb_tbl_unmap_single.
    - * DMA_ATTR_SKIP_CPU_SYNC is optional.
    - */
    - swiotlb_tbl_unmap_single(hwdev, paddr, size, DMA_TO_DEVICE,
    - DMA_ATTR_SKIP_CPU_SYNC);
    }
    EXPORT_SYMBOL(swiotlb_free_coherent);

    @@ -1103,9 +1112,7 @@ void *swiotlb_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
    void swiotlb_free(struct device *dev, size_t size, void *vaddr,
    dma_addr_t dma_addr, unsigned long attrs)
    {
    - if (is_swiotlb_buffer(dma_to_phys(dev, dma_addr)))
    - swiotlb_free_coherent(dev, size, vaddr, dma_addr);
    - else
    + if (!swiotlb_free_buffer(dev, size, dma_addr))
    dma_direct_free(dev, size, vaddr, dma_addr, attrs);
    }

    --
    2.14.2
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