From mboxrd@z Thu Jan  1 00:00:00 1970
From: Olaf Hering <olaf@aepfle.de>
Subject: Re: [PATCH 1 of 5] xentrace: fix t_info_pages
	calculation for the default case
Date: Wed, 23 Mar 2011 12:20:40 +0100
Message-ID: <20110323112040.GB28535@aepfle.de>
References: <4D89D5920200007800037DBE@vpn.id2.novell.com>
	<C9AF7A58.15475%keir.xen@gmail.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=utf-8
Return-path: <xen-devel-bounces@lists.xensource.com>
Content-Disposition: inline
In-Reply-To: <C9AF7A58.15475%keir.xen@gmail.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: Keir Fraser <keir.xen@gmail.com>
Cc: xen-devel@lists.xensource.com, George Dunlap <george.dunlap@citrix.com>, Jan Beulich <JBeulich@novell.com>
List-Id: xen-devel@lists.xenproject.org

On Wed, Mar 23, Keir Fraser wrote:

> 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).

I did not know about PFN_UP() until now, using it would work as well.

Olaf