Drop structure which is only set but never read.  Drop variables which are
only set and never read.  Convert one long switch into two shorter ones.

Add cpu_relax() in busy waiting loop.
Signed-off-by: NKrzysztof Helt <krzysztof.h1@wp.pl>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>