[PATCH] [PPC64] No prefetch for NULL pointers

[Anton Blanchard]

> I wonder if prefetch(0) is a common thing, or if only one or two callsites
> do it?
> 
> If the latter then perhaps this would be better fixed at the callsites, so
> well-behaved callsites don't bear the cost of the (unneeded) test?

NULL terminated lists were what seemed to be hurting us most, for
example d_lookup.

Prefetch (together with likely/unlikely) are the latest fad in Linux
programming and I dont trust everyone to get it right :)

Anton