Re: [XenPPC] [xenppc-unstable] [ppc] Handle 2 forms of NULL gues handle

[Hollis Blanchard <hollisb@xxxxxxxxxx>]

On Thu, 2006-07-27 at 18:10 -0400, Jimi Xenidis wrote:
> On Jul 27, 2006, at 5:13 PM, Hollis Blanchard wrote:
> >
> > diff -r 72c8bc5d88f4 drivers/xen/core/xencomm.c
> > --- a/drivers/xen/core/xencomm.c        Thu Jun 29 13:04:30 2006 -0400
> > +++ b/drivers/xen/core/xencomm.c        Thu Jul 27 15:58:58 2006 -0500
> > @@ -58,6 +58,10 @@ static int __xencomm_init(struct xencomm
> >  {
> >         unsigned long recorded = 0;
> >         int i = 0;
> > +
> > +       /* special-case NULL pointers for easy detection on the Xen  
> > side */
> > +       if (buffer == NULL)
> > +               desc->nr_addrs = 0;
> >
> >         /* record the physical pages used */
> >         while ((recorded < bytes) && (i < desc->nr_addrs)) {
> >
> 
> not so simple because 'bytes' is non-zero and we'll end up reporting  
> ENOSPC.

It is a caller error to pass a NULL pointer and claim it holds >0 bytes.
If this is a recurring problem we should add
        BUG_ON((buffer == NULL) && (bytes != 0));

-- 
Hollis Blanchard
IBM Linux Technology Center


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