Merge branch 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

[safe/jmp/linux-2.6] / kernel / time / tick-common.c

diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c
index 63e05d4..83c4417 100644 (file)
--- a/kernel/time/tick-common.c
+++ b/kernel/time/tick-common.c
@@ -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);
        }
 }
@@ -274,6 +284,21 @@ out_bc:
 }
 
 /*
+ * Transfer the do_timer job away from a dying cpu.
+ *
+ * Called with interrupts disabled.
+ */
+static void tick_handover_do_timer(int *cpup)
+{
+       if (*cpup == tick_do_timer_cpu) {
+               int cpu = cpumask_first(cpu_online_mask);
+
+               tick_do_timer_cpu = (cpu < nr_cpu_ids) ? cpu :
+                       TICK_DO_TIMER_NONE;
+       }
+}
+
+/*
  * Shutdown an event device on a given cpu:
  *
  * This is called on a life CPU, when a CPU is dead. So we cannot
@@ -297,13 +322,6 @@ static void tick_shutdown(unsigned int *cpup)
                clockevents_exchange_device(dev, NULL);
                td->evtdev = NULL;
        }
-       /* Transfer the do_timer job away from this cpu */
-       if (*cpup == tick_do_timer_cpu) {
-               int cpu = cpumask_first(cpu_online_mask);
-
-               tick_do_timer_cpu = (cpu < nr_cpu_ids) ? cpu :
-                       TICK_DO_TIMER_NONE;
-       }
        spin_unlock_irqrestore(&tick_device_lock, flags);
 }
 
@@ -357,6 +375,10 @@ static int tick_notify(struct notifier_block *nb, unsigned long reason,
                tick_broadcast_oneshot_control(reason);
                break;
 
+       case CLOCK_EVT_NOTIFY_CPU_DYING:
+               tick_handover_do_timer(dev);
+               break;
+
        case CLOCK_EVT_NOTIFY_CPU_DEAD:
                tick_shutdown_broadcast_oneshot(dev);
                tick_shutdown_broadcast(dev);