Merge branch 'timers/urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/tip...
Linus Torvalds [Tue, 5 May 2009 19:09:38 +0000 (12:09 -0700)]
* 'timers/urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  clockevents: prevent endless loop in tick_handle_periodic()

kernel/time/tick-common.c

index 21a5ca8..83c4417 100644 (file)
@@ -93,7 +93,17 @@ void tick_handle_periodic(struct clock_event_device *dev)
        for (;;) {
                if (!clockevents_program_event(dev, next, ktime_get()))
                        return;
-               tick_periodic(cpu);
+               /*
+                * Have to be careful here. If we're in oneshot mode,
+                * before we call tick_periodic() in a loop, we need
+                * to be sure we're using a real hardware clocksource.
+                * Otherwise we could get trapped in an infinite
+                * loop, as the tick_periodic() increments jiffies,
+                * when then will increment time, posibly causing
+                * the loop to trigger again and again.
+                */
+               if (timekeeping_valid_for_hres())
+                       tick_periodic(cpu);
                next = ktime_add(next, tick_period);
        }
 }