[ +Michael - FYI this is straight on top of 4.10-rc5 ]
On 25/01/17 18:31, Robin Murphy wrote:
> When bypassing SWIOTLB on small-memory systems, we need to avoid calling
> into swiotlb_dma_mapping_error() in exactly the same way as we avoid
> swiotlb_dma_supported(), because the former also relies on SWIOTLB state
> being initialised.
>
> Under the assumptions for which we skip SWIOTLB, dma_map_{single,page}()
> will only ever return the DMA-offset-adjusted physical address of the
> page passed in, thus we can report success unconditionally.
>
> Fixes: b67a8b29df7e ("arm64: mm: only initialize swiotlb when necessary")
> CC: stable@xxxxxxxxxxxxxxx
> CC: Jisheng Zhang <jszhang@xxxxxxxxxxx>
> Reported-by: Aaro Koskinen <aaro.koskinen@xxxxxx>
> Signed-off-by: Robin Murphy <robin.murphy@xxxxxxx>
> ---
>
> v2: Get the return value the right way round this time... After some
> careful reasoning it really is that simple.
>
> arch/arm64/mm/dma-mapping.c | 9 ++++++++-
> 1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
> index e04082700bb1..1ffb7d5d299a 100644
> --- a/arch/arm64/mm/dma-mapping.c
> +++ b/arch/arm64/mm/dma-mapping.c
> @@ -352,6 +352,13 @@ static int __swiotlb_dma_supported(struct device *hwdev, u64 mask)
> return 1;
> }
>
> +static int __swiotlb_dma_mapping_error(struct device *hwdev, dma_addr_t addr)
> +{
> + if (swiotlb)
> + return swiotlb_dma_mapping_error(hwdev, addr);
> + return 0;
> +}
> +
> static struct dma_map_ops swiotlb_dma_ops = {
> .alloc = __dma_alloc,
> .free = __dma_free,
> @@ -366,7 +373,7 @@ static struct dma_map_ops swiotlb_dma_ops = {
> .sync_sg_for_cpu = __swiotlb_sync_sg_for_cpu,
> .sync_sg_for_device = __swiotlb_sync_sg_for_device,
> .dma_supported = __swiotlb_dma_supported,
> - .mapping_error = swiotlb_dma_mapping_error,
> + .mapping_error = __swiotlb_dma_mapping_error,
> };
>
> static int __init atomic_pool_init(void)
>
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