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-rw-r--r--kernel/softlockup.c35
1 files changed, 29 insertions, 6 deletions
diff --git a/kernel/softlockup.c b/kernel/softlockup.c
index 81d43caa201..5ea631742db 100644
--- a/kernel/softlockup.c
+++ b/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;