powerpc: Max next_tb to prevent from replaying timer interrupt

With lazy interrupt, we always call __check_irq_replaysome with
decrementers_next_tb to check if we need to replay timer interrupt.
So in hotplug case we also need to set decrementers_next_tb as MAX
to make sure __check_irq_replay don't replay timer interrupt
when return as we expect, otherwise we'll trap here infinitely.

Signed-off-by: Tiejun Chen <tiejun.chen@windriver.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/kernel/time.c

@@ -494,10 +494,15 @@ void timer_interrupt(struct pt_regs * regs)
 	set_dec(DECREMENTER_MAX);
 
 	/* Some implementations of hotplug will get timer interrupts while
-	 * offline, just ignore these
+	 * offline, just ignore these and we also need to set
+	 * decrementers_next_tb as MAX to make sure __check_irq_replay
+	 * don't replay timer interrupt when return, otherwise we'll trap
+	 * here infinitely :(
 	 */
-	if (!cpu_online(smp_processor_id()))
+	if (!cpu_online(smp_processor_id())) {
+		*next_tb = ~(u64)0;
 		return;
+	}
 
 	/* Conditionally hard-enable interrupts now that the DEC has been
 	 * bumped to its maximum value