The following patch fixes the situation where the loop condition could
generate a next_dec of zero while exiting the loop.  This is suboptimal on
Classic PPC because it forces another interrupt to occur and reenter the
handler.  It is fatal on Book E cores, because their decrementer is stopped
when writing a zero (Classic interrupts on a 0->-1 transition, Book E
interrupts on a 1->0 transition).  Instead, stay in the loop on a
next_dec==0.
Signed-off-by: Matt Porter <mporter@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>