Re: [PATCH 3/4] kvm: powerpc: define a linux pte lookup function

[Paul Mackerras <paulus@samba.org>]

On Wed, Oct 09, 2013 at 12:47:31PM -0500, Scott Wood wrote:
> On Wed, 2013-10-09 at 03:48 -0500, Bhushan Bharat-R65777 wrote:
> > 
> > What lookup_linux_pte_and_update() does:-
> >  - find_linux_pte_or_hugepte()
> >  - does size and some other trivial checks
> >  - Then atomically update the pte:-
> >    => while()
> >    => wait till _PAGE_BUSY is clear
> >    => atomically update the pte
> >    => if not updated then go back to while() above else break
> > 
> > 
> > While what lookup_linux_pte() does:-
> >  - find_linux_pte_or_hugepte()
> >  - does size and some other trivial checks
> >  - wait till _PAGE_BUSY is clear
> >  - return pte
> > 
> > I am finding it difficult to call lookup_linux_pte() from lookup_linux_pte_and_update().
> 
> You could factor out a common lookup_linux_ptep().

I don't really think it's enough code to be worth wringing out the
last drop of duplication.  However, if he removed the checks for
_PAGE_BUSY and _PAGE_PRESENT as I suggested in another mail, and made
it return the pte pointer rather than the value, it would then
essentially be a lookup_linux_ptep() as you suggest.

Paul.