RE: [PATCH 1/2] mm: Fix struct page layout on 32-bit systems

[David Laight]

From: Matthew Wilcox <willy@xxxxxxxxxxxxx>
> Sent: 17 April 2021 03:45
> 
> Replacement patch to fix compiler warning.
...
>  static inline dma_addr_t page_pool_get_dma_addr(struct page *page)
>  {
> -	return page->dma_addr;
> +	dma_addr_t ret = page->dma_addr[0];
> +	if (sizeof(dma_addr_t) > sizeof(unsigned long))
> +		ret |= (dma_addr_t)page->dma_addr[1] << 16 << 16;

Ugly as well.

Why not just replace the (dma_addr_t) cast with a (u64) one?
Looks better than the double shift.

Same could be done for the '>> 32'.
Is there an upper_32_bits() that could be used??

	David

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