Re: mm: slab - __cache_alloc NULL prefetch fix

[Pekka Enberg]

Valdis.Kletnieks@xxxxxx wrote:
> On Thu, 20 Nov 2008 19:44:00 +0300, Cyrill Gorcunov said:
>
> > -	prefetchw(objp);
> >  
> > -	if (likely(objp))
> > +	if (likely(objp)) {
> > +		prefetchw(objp);
> >  		kmemcheck_slab_alloc(cachep, flags, objp, obj_size(cachep));
> > +	}
>
> Although it probably makes sense to not bother prefetching NULL, I also
> need to wonder how useful it is to prefetch something that we then
> turn around and dereference in the very next line of code.

Note that kmemcheck_slab_alloc() is going to be a no-op on anything but 
a special developer or tester debug config.
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