[PATCH] ppc32: optimize/fix timer_interrupt loop

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>

arch/ppc/kernel/time.c

@@ -161,7 +161,7 @@ void timer_interrupt(struct pt_regs * regs)
 
 	irq_enter();
 
-	while ((next_dec = tb_ticks_per_jiffy - tb_delta(&jiffy_stamp)) < 0) {
+	while ((next_dec = tb_ticks_per_jiffy - tb_delta(&jiffy_stamp)) <= 0) {
 		jiffy_stamp += tb_ticks_per_jiffy;
 		
 		ppc_do_profile(regs);