linux-kernel - Re: [PATCH 03/11] xen/arm: pass one less argument to dma_cache

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Date:   Fri, 16 Aug 2019 14:37:58 +0100
From:   Robin Murphy <robin.murphy@....com>
To:     Christoph Hellwig <hch@....de>,
        Stefano Stabellini <sstabellini@...nel.org>,
        Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Cc:     xen-devel@...ts.xenproject.org, iommu@...ts.linux-foundation.org,
        x86@...nel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 03/11] xen/arm: pass one less argument to dma_cache_maint

On 16/08/2019 14:00, Christoph Hellwig wrote:
> Instead of taking apart the dma address in both callers do it inside
> dma_cache_maint itself.
> 
> Signed-off-by: Christoph Hellwig <hch@....de>
> ---
>   arch/arm/xen/mm.c | 10 ++++++----
>   1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/arm/xen/mm.c b/arch/arm/xen/mm.c
> index 90574d89d0d4..d9da24fda2f7 100644
> --- a/arch/arm/xen/mm.c
> +++ b/arch/arm/xen/mm.c
> @@ -43,13 +43,15 @@ static bool hypercall_cflush = false;
>   
>   /* functions called by SWIOTLB */
>   
> -static void dma_cache_maint(dma_addr_t handle, unsigned long offset,
> -	size_t size, enum dma_data_direction dir, enum dma_cache_op op)
> +static void dma_cache_maint(dma_addr_t handle, size_t size,
> +		enum dma_data_direction dir, enum dma_cache_op op)
>   {
>   	struct gnttab_cache_flush cflush;
>   	unsigned long xen_pfn;
> +	unsigned long offset = handle & ~PAGE_MASK;
>   	size_t left = size;
>   
> +	offset &= PAGE_MASK;

Ahem... presumably that should be handle, not offset.

Robin.

>   	xen_pfn = (handle >> XEN_PAGE_SHIFT) + offset / XEN_PAGE_SIZE;
>   	offset %= XEN_PAGE_SIZE;
>   
> @@ -86,13 +88,13 @@ static void dma_cache_maint(dma_addr_t handle, unsigned long offset,
>   static void __xen_dma_page_dev_to_cpu(struct device *hwdev, dma_addr_t handle,
>   		size_t size, enum dma_data_direction dir)
>   {
> -	dma_cache_maint(handle & PAGE_MASK, handle & ~PAGE_MASK, size, dir, DMA_UNMAP);
> +	dma_cache_maint(handle, size, dir, DMA_UNMAP);
>   }
>   
>   static void __xen_dma_page_cpu_to_dev(struct device *hwdev, dma_addr_t handle,
>   		size_t size, enum dma_data_direction dir)
>   {
> -	dma_cache_maint(handle & PAGE_MASK, handle & ~PAGE_MASK, size, dir, DMA_MAP);
> +	dma_cache_maint(handle, size, dir, DMA_MAP);
>   }
>   
>   void __xen_dma_map_page(struct device *hwdev, struct page *page,
>