This patch mirrors the recent changes on x86 to call preempt_schedule
rather than schedule in the exception exit path, in the case where the
preempt_count is zero and the TIF_NEED_RESCHED bit is set.

I'm a little concerned that this means that we have a window where
interrupts are enabled and we are on our way into preempt_schedule,
but preempt_count is still zero.  Ingo's proposed preempt_schedule_irq
would fix this, and I think something like that should go in.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>