linux-kernel - Re: [Xen-devel] [PATCH] x86/xen: Use DIV_ROUND

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Date:	Wed, 29 Jun 2016 09:34:04 -0600
From:	"Jan Beulich" <JBeulich@...e.com>
To:	"Amitoj Kaur Chawla" <amitoj1606@...il.com>
Cc:	<david.vrabel@...rix.com>, <x86@...nel.org>, <tglx@...utronix.de>,
	<julia.lawall@...6.fr>, <xen-devel@...ts.xenproject.org>,
	<boris.ostrovsky@...cle.com>, <mingo@...hat.com>,
	"Juergen Gross" <JGross@...e.com>, <linux-kernel@...r.kernel.org>,
	<hpa@...or.com>
Subject: Re: [Xen-devel] [PATCH] x86/xen: Use DIV_ROUND_UP

>>> On 29.06.16 at 17:00, <amitoj1606@...il.com> wrote:
> --- a/arch/x86/xen/enlighten.c
> +++ b/arch/x86/xen/enlighten.c
> @@ -591,7 +591,7 @@ static void xen_load_gdt(const struct desc_ptr *dtr)
>  {
>  	unsigned long va = dtr->address;
>  	unsigned int size = dtr->size + 1;
> -	unsigned pages = (size + PAGE_SIZE - 1) / PAGE_SIZE;
> +	unsigned pages = DIV_ROUND_UP(size, PAGE_SIZE);
>  	unsigned long frames[pages];
>  	int f;
>  
> @@ -640,7 +640,7 @@ static void __init xen_load_gdt_boot(const struct desc_ptr *dtr)
>  {
>  	unsigned long va = dtr->address;
>  	unsigned int size = dtr->size + 1;
> -	unsigned pages = (size + PAGE_SIZE - 1) / PAGE_SIZE;
> +	unsigned pages = DIV_ROUND_UP(size, PAGE_SIZE);
>  	unsigned long frames[pages];
>  	int f;
>  

Perhaps even more readable would be PFN_DOWN()?

Jan