1 files changed, 45 insertions, 7 deletions

diff --git a/kernel/softlockup.c b/kernel/softlockup.c
index 50afeb813305..0131e296ffb4 100644
--- a/kernel/softlockup.c
+++ b/kernel/softlockup.c
@@ -34,12 +34,32 @@ static struct notifier_block panic_block = {
 	.notifier_call = softlock_panic,
 };
 
+/*
+ * Returns seconds, approximately.  We don't need nanosecond
+ * resolution, and we don't need to waste time with a big divide when
+ * 2^30ns == 1.074s.
+ */
+static unsigned long get_timestamp(void)
+{
+	return sched_clock() >> 30;  /* 2^30 ~= 10^9 */
+}
+
 void touch_softlockup_watchdog(void)
 {
-	__raw_get_cpu_var(touch_timestamp) = jiffies;
+	__raw_get_cpu_var(touch_timestamp) = get_timestamp();
 }
 EXPORT_SYMBOL(touch_softlockup_watchdog);
 
+void touch_all_softlockup_watchdogs(void)
+{
+	int cpu;
+
+	/* Cause each CPU to re-update its timestamp rather than complain */
+	for_each_online_cpu(cpu)
+		per_cpu(touch_timestamp, cpu) = 0;
+}
+EXPORT_SYMBOL(touch_all_softlockup_watchdogs);
+
 /*
  * This callback runs from the timer interrupt, and checks
  * whether the watchdog thread has hung or not:
@@ -48,9 +68,18 @@ void softlockup_tick(void)
 {
 	int this_cpu = smp_processor_id();
 	unsigned long touch_timestamp = per_cpu(touch_timestamp, this_cpu);
+	unsigned long print_timestamp;
+	unsigned long now;
+
+	if (touch_timestamp == 0) {
+		touch_softlockup_watchdog();
+		return;
+	}
+
+	print_timestamp = per_cpu(print_timestamp, this_cpu);
 
-	/* prevent double reports: */
-	if (per_cpu(print_timestamp, this_cpu) == touch_timestamp ||
+	/* report at most once a second */
+	if (print_timestamp < (touch_timestamp + 1) ||
 		did_panic ||
 			!per_cpu(watchdog_task, this_cpu))
 		return;
@@ -61,12 +90,14 @@ void softlockup_tick(void)
 		return;
 	}
 
+	now = get_timestamp();
+
 	/* Wake up the high-prio watchdog task every second: */
-	if (time_after(jiffies, touch_timestamp + HZ))
+	if (now > (touch_timestamp + 1))
 		wake_up_process(per_cpu(watchdog_task, this_cpu));
 
 	/* Warn about unreasonable 10+ seconds delays: */
-	if (time_after(jiffies, touch_timestamp + 10*HZ)) {
+	if (now > (touch_timestamp + 10)) {
 		per_cpu(print_timestamp, this_cpu) = touch_timestamp;
 
 		spin_lock(&print_lock);
@@ -82,11 +113,14 @@ void softlockup_tick(void)
  */
 static int watchdog(void * __bind_cpu)
 {
-	struct sched_param param = { .sched_priority = 99 };
+	struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
 
 	sched_setscheduler(current, SCHED_FIFO, &param);
 	current->flags |= PF_NOFREEZE;
 
+	/* initialize timestamp */
+	touch_softlockup_watchdog();
+
 	/*
 	 * Run briefly once per second to reset the softlockup timestamp.
 	 * If this gets delayed for more than 10 seconds then the
@@ -112,27 +146,31 @@ cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
 
 	switch (action) {
 	case CPU_UP_PREPARE:
+	case CPU_UP_PREPARE_FROZEN:
 		BUG_ON(per_cpu(watchdog_task, hotcpu));
 		p = kthread_create(watchdog, hcpu, "watchdog/%d", hotcpu);
 		if (IS_ERR(p)) {
 			printk("watchdog for %i failed\n", hotcpu);
 			return NOTIFY_BAD;
 		}
-  		per_cpu(touch_timestamp, hotcpu) = jiffies;
+  		per_cpu(touch_timestamp, hotcpu) = 0;
   		per_cpu(watchdog_task, hotcpu) = p;
 		kthread_bind(p, hotcpu);
  		break;
 	case CPU_ONLINE:
+	case CPU_ONLINE_FROZEN:
 		wake_up_process(per_cpu(watchdog_task, hotcpu));
 		break;
 #ifdef CONFIG_HOTPLUG_CPU
 	case CPU_UP_CANCELED:
+	case CPU_UP_CANCELED_FROZEN:
 		if (!per_cpu(watchdog_task, hotcpu))
 			break;
 		/* Unbind so it can run.  Fall thru. */
 		kthread_bind(per_cpu(watchdog_task, hotcpu),
 			     any_online_cpu(cpu_online_map));
 	case CPU_DEAD:
+	case CPU_DEAD_FROZEN:
 		p = per_cpu(watchdog_task, hotcpu);
 		per_cpu(watchdog_task, hotcpu) = NULL;
 		kthread_stop(p);