Using yield() is generally wrong.  Warn on its use.
Signed-off-by: NJoe Perches <joe@perches.com>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>