---

yaml
---
r: 54635
b: refs/heads/master
c: 966812d
h: refs/heads/master
i:
  54633: 587bf72
  54631: 8da34c2
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 8524070b7982d76258942275908b7434cfcab4b4
+refs/heads/master: 966812dc98e6a7fcdf759cbfa0efab77500a8868

trunk/kernel/softlockup.c

@@ -34,9 +34,19 @@ 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);
 
@@ -48,9 +58,17 @@ 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;
 
-	/* prevent double reports: */
-	if (per_cpu(print_timestamp, this_cpu) == touch_timestamp ||
+	/* watchdog task hasn't updated timestamp yet */
+	if (touch_timestamp == 0)
+		return;
+
+	print_timestamp = per_cpu(print_timestamp, this_cpu);
+
+	/* report at most once a second */
+	if (print_timestamp < (touch_timestamp + 1) ||
 		did_panic ||
 			!per_cpu(watchdog_task, this_cpu))
 		return;
@@ -61,12 +79,14 @@ 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);
@@ -87,6 +107,9 @@ static int watchdog(void * __bind_cpu)
 	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
@@ -118,7 +141,7 @@ cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
 			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;