Re: [PATCH] arch : arm : add a criteria for pfn_valid

[Matthew Wilcox]

On Sat, Aug 17, 2019 at 11:00:13AM +0800, Zhaoyang Huang wrote:
>  #ifdef CONFIG_HAVE_ARCH_PFN_VALID
>  int pfn_valid(unsigned long pfn)
>  {
> -	return memblock_is_map_memory(__pfn_to_phys(pfn));
> +	return (pfn > max_pfn) ?
> +		false : memblock_is_map_memory(__pfn_to_phys(pfn));
>  }

This is a really awkward way to use the ternary operator.  It's easier to
read if you just:

+	if (pfn > max_pfn)
+		return 0;
 	return memblock_is_map_memory(__pfn_to_phys(pfn));

(if you really wanted to be clever ... er, obscure, you'd've written:

	return (pfn <= max_pfn) && memblock_is_map_memory(__pfn_to_phys(pfn));

... but don't do that)

Also, why is this diverged between arm and arm64?