From mboxrd@z Thu Jan  1 00:00:00 1970
From: Keir Fraser <keir.xen@gmail.com>
Subject: Re: [PATCH 1 of 5] xentrace: fix t_info_pages calculation
	for the default case
Date: Wed, 23 Mar 2011 10:22:16 +0000
Message-ID: <C9AF7A58.15475%keir.xen@gmail.com>
References: <4D89D5920200007800037DBE@vpn.id2.novell.com>
Mime-Version: 1.0
Content-Type: text/plain;
	charset="US-ASCII"
Content-Transfer-Encoding: 7bit
Return-path: <xen-devel-bounces@lists.xensource.com>
In-Reply-To: <4D89D5920200007800037DBE@vpn.id2.novell.com>
List-Unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>,
	<mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
List-Post: <mailto:xen-devel@lists.xensource.com>
List-Help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-Subscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>,
	<mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
Sender: xen-devel-bounces@lists.xensource.com
Errors-To: xen-devel-bounces@lists.xensource.com
To: Jan Beulich <JBeulich@novell.com>, Olaf Hering <olaf@aepfle.de>
Cc: xen-devel@lists.xensource.com, George Dunlap <george.dunlap@citrix.com>
List-Id: xen-devel@lists.xenproject.org

On 23/03/2011 10:12, "Jan Beulich" <JBeulich@novell.com> wrote:

>>      t_info_pages /= PAGE_SIZE;
>> -    if ( t_info_pages % PAGE_SIZE )
>> +    if ( t_info_pages % PAGE_SIZE || t_info_pages == 0 )
> 
> While certainly not having a significant effect, to the unsuspecting
> reader this looks like a bug - is it really meant to be a remainder
> operation on the *result* of a division (rather than on the original
> dividend)? Couldn't you just (ab)use PFN_UP() here?

By which you mean to replace the division and subsequent if statement with
t_info_pages = PFN_UP(t_info_pages).

That would make sense to me. The suggested change in the patch series looks
nonsensical.

 -- Keir