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-rw-r--r--kernel/time/clocksource.c33
1 files changed, 30 insertions, 3 deletions
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index e0c86ad6e9fb..a0af4ffcb6e5 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -149,15 +149,42 @@ static void clocksource_watchdog_work(struct work_struct *work)
kthread_run(clocksource_watchdog_kthread, NULL, "kwatchdog");
}
-static void clocksource_unstable(struct clocksource *cs, int64_t delta)
+static void __clocksource_unstable(struct clocksource *cs)
{
- printk(KERN_WARNING "Clocksource %s unstable (delta = %Ld ns)\n",
- cs->name, delta);
cs->flags &= ~(CLOCK_SOURCE_VALID_FOR_HRES | CLOCK_SOURCE_WATCHDOG);
cs->flags |= CLOCK_SOURCE_UNSTABLE;
schedule_work(&watchdog_work);
}
+static void clocksource_unstable(struct clocksource *cs, int64_t delta)
+{
+ printk(KERN_WARNING "Clocksource %s unstable (delta = %Ld ns)\n",
+ cs->name, delta);
+ __clocksource_unstable(cs);
+}
+
+/**
+ * clocksource_mark_unstable - mark clocksource unstable via watchdog
+ * @cs: clocksource to be marked unstable
+ *
+ * This function is called instead of clocksource_change_rating from
+ * cpu hotplug code to avoid a deadlock between the clocksource mutex
+ * and the cpu hotplug mutex. It defers the update of the clocksource
+ * to the watchdog thread.
+ */
+void clocksource_mark_unstable(struct clocksource *cs)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&watchdog_lock, flags);
+ if (!(cs->flags & CLOCK_SOURCE_UNSTABLE)) {
+ if (list_empty(&cs->wd_list))
+ list_add(&cs->wd_list, &watchdog_list);
+ __clocksource_unstable(cs);
+ }
+ spin_unlock_irqrestore(&watchdog_lock, flags);
+}
+
static void clocksource_watchdog(unsigned long data)
{
struct clocksource *cs;