linux-kernel - Re: [PATCH] dma-debug: fix physical address calculation for struct dma_debug

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Message-ID: <20241128-caa8ebcbb224ba75d406a450-pchelkin@ispras.ru>
Date: Thu, 28 Nov 2024 11:50:30 +0300
From: Fedor Pchelkin <pchelkin@...ras.ru>
To: Christoph Hellwig <hch@....de>
Cc: Marek Szyprowski <m.szyprowski@...sung.com>,
	Robin Murphy <robin.murphy@....com>, iommu@...ts.linux.dev,
	linux-kernel@...r.kernel.org, lvc-project@...uxtesting.org
Subject: Re: [PATCH] dma-debug: fix physical address calculation for struct
 dma_debug_entry

On Thu, 28. Nov 04:50, Christoph Hellwig wrote:
> Is it ok for you if I fold in the following cleanup to have a helper
> instead of the duplicate very dense expression?
> 
> diff --git a/kernel/dma/debug.c b/kernel/dma/debug.c
> index 27ade2bab531..e43c6de2bce4 100644
> --- a/kernel/dma/debug.c
> +++ b/kernel/dma/debug.c
> @@ -1377,6 +1377,18 @@ void debug_dma_unmap_sg(struct device *dev, struct scatterlist *sglist,
>  	}
>  }
>  
> +static phys_addr_t virt_to_paddr(void *virt)
> +{
> +	struct page *page;
> +
> +	if (is_vmalloc_addr(virt))
> +		page = vmalloc_to_page(virt);
> +	else
> +		page = virt_to_page(virt);
> +
> +	return page_to_phys(page) + offset_in_page(virt);
> +}
> +
>  void debug_dma_alloc_coherent(struct device *dev, size_t size,
>  			      dma_addr_t dma_addr, void *virt,
>  			      unsigned long attrs)
> @@ -1399,9 +1411,7 @@ void debug_dma_alloc_coherent(struct device *dev, size_t size,
>  
>  	entry->type      = dma_debug_coherent;
>  	entry->dev       = dev;
> -	entry->paddr	 = page_to_phys((is_vmalloc_addr(virt) ?
> -				vmalloc_to_page(virt) : virt_to_page(virt))) +
> -				offset_in_page(virt);
> +	entry->paddr	 = virt_to_paddr(virt);
>  	entry->size      = size;
>  	entry->dev_addr  = dma_addr;
>  	entry->direction = DMA_BIDIRECTIONAL;
> @@ -1424,9 +1434,7 @@ void debug_dma_free_coherent(struct device *dev, size_t size,
>  	if (!is_vmalloc_addr(virt) && !virt_addr_valid(virt))
>  		return;
>  
> -	ref.paddr = page_to_phys((is_vmalloc_addr(virt) ?
> -			vmalloc_to_page(virt) : virt_to_page(virt))) +
> -			offset_in_page(virt);
> +	ref.paddr = virt_to_paddr(virt);
>  
>  	if (unlikely(dma_debug_disabled()))
>  		return;

No problem. It actually looks more readable.

--
Thanks,
Fedor