Re: [Xen-devel] Ping: [PATCH] use clear_domain_page() instead of open coding it

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

On Mon, 2015-10-26 at 07:06 -0600, Jan Beulich wrote:
> > > > On 19.10.15 at 16:51, <JBeulich@xxxxxxxx> wrote:
> 
> "REST" maintainers, could I please get an ack or otherwise on this
> common code change?
> 
> Thanks, Jan
> 
> > --- a/xen/common/page_alloc.c
> > +++ b/xen/common/page_alloc.c
> > @@ -1959,22 +1959,16 @@ __initcall(pagealloc_keyhandler_init);
> >  
> >  void scrub_one_page(struct page_info *pg)
> >  {
> > -    void *p;
> > -
> >      if ( unlikely(pg->count_info & PGC_broken) )
> >          return;
> >  
> > -    p = __map_domain_page(pg);
> > -
> >  #ifndef NDEBUG
> >      /* Avoid callers relying on allocations returning zeroed pages. */
> > -    memset(p, 0xc2, PAGE_SIZE);
> > +    unmap_domain_page(memset(__map_domain_page(pg), 0xc2, PAGE_SIZE));

I'm not madly keep on this clever nesting of the map/memset/unmap and would
have preferred a more localised void *p (or a memset_domain_page helper
maybe), but I don't mind enough to block this over:

Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>

> >  #else
> >      /* For a production build, clear_page() is the fastest way to
> > scrub. */
> > -    clear_page(p);
> > +    clear_domain_page(_mfn(page_to_mfn(pg)));
> >  #endif
> > -
> > -    unmap_domain_page(p);
> >  }
> >  
> >  static void dump_heap(unsigned char key)
> 
> 
> 

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