Re: [PATCH v9 09/14] swiotlb: Refactor swiotlb_tbl_unmap_single

[Christoph Hellwig <hch@xxxxxx>]

On Fri, Jun 11, 2021 at 11:26:54PM +0800, Claire Chang wrote:
> Add a new function, release_slots, to make the code reusable for supporting
> different bounce buffer pools, e.g. restricted DMA pool.
> 
> Signed-off-by: Claire Chang <tientzu@xxxxxxxxxxxx>
> ---
>  kernel/dma/swiotlb.c | 35 ++++++++++++++++++++---------------
>  1 file changed, 20 insertions(+), 15 deletions(-)
> 
> diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
> index 364c6c822063..a6562573f090 100644
> --- a/kernel/dma/swiotlb.c
> +++ b/kernel/dma/swiotlb.c
> @@ -554,27 +554,15 @@ phys_addr_t swiotlb_tbl_map_single(struct device *dev, 
> phys_addr_t orig_addr,
>       return tlb_addr;
>  }
>  
> -/*
> - * tlb_addr is the physical address of the bounce buffer to unmap.
> - */
> -void swiotlb_tbl_unmap_single(struct device *hwdev, phys_addr_t tlb_addr,
> -                           size_t mapping_size, enum dma_data_direction dir,
> -                           unsigned long attrs)
> +static void release_slots(struct device *dev, phys_addr_t tlb_addr)
>  {
> -     struct io_tlb_mem *mem = hwdev->dma_io_tlb_mem;
> +     struct io_tlb_mem *mem = dev->dma_io_tlb_mem;
>       unsigned long flags;
> -     unsigned int offset = swiotlb_align_offset(hwdev, tlb_addr);
> +     unsigned int offset = swiotlb_align_offset(dev, tlb_addr);
>       int index = (tlb_addr - offset - mem->start) >> IO_TLB_SHIFT;
>       int nslots = nr_slots(mem->slots[index].alloc_size + offset);
>       int count, i;
>  
> -     /*
> -      * First, sync the memory before unmapping the entry
> -      */
> -     if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
> -         (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL))
> -             swiotlb_bounce(hwdev, tlb_addr, mapping_size, DMA_FROM_DEVICE);
> -
>       /*
>        * Return the buffer to the free list by setting the corresponding
>        * entries to indicate the number of contiguous entries available.
> @@ -609,6 +597,23 @@ void swiotlb_tbl_unmap_single(struct device *hwdev, 
> phys_addr_t tlb_addr,
>       spin_unlock_irqrestore(&mem->lock, flags);
>  }
>  
> +/*
> + * tlb_addr is the physical address of the bounce buffer to unmap.
> + */
> +void swiotlb_tbl_unmap_single(struct device *dev, phys_addr_t tlb_addr,
> +                           size_t mapping_size, enum dma_data_direction dir,
> +                           unsigned long attrs)
> +{
> +     /*
> +      * First, sync the memory before unmapping the entry
> +      */
> +     if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
> +         (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL))
> +             swiotlb_bounce(dev, tlb_addr, mapping_size, DMA_FROM_DEVICE);
> +
> +     release_slots(dev, tlb_addr);

Can you give this a swiotlb_ prefix?

Otherwise looks good:

Reviewed-by: Christoph Hellwig <hch@xxxxxx>