Re: [Xen-devel] [PATCH 1 of 5] xentrace: fix t_info_pages calculation for the default case

[Olaf Hering <olaf@xxxxxxxxx>]

On Wed, Mar 23, Keir Fraser wrote:

> On 23/03/2011 11:20, "Olaf Hering" <olaf@xxxxxxxxx> 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.
> 
> As opposed to the existing code (even including your latest patch) which
> doesn't work properly. You need to respin at least your patch 1/5.

I will send the bugfix now.

Olaf

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