---

yaml
---
r: 163080
b: refs/heads/master
c: 7285dd7
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 90cba64a5f672a239f43ec5cb9a11b806887331e
+refs/heads/master: 7285dd7fd375763bfb8ab1ac9cf3f1206f503c16

trunk/arch/x86/kernel/tsc.c

@@ -767,12 +767,14 @@ void mark_tsc_unstable(char *reason)
 {
 	if (!tsc_unstable) {
 		tsc_unstable = 1;
-		printk("Marking TSC unstable due to %s\n", reason);
+		printk(KERN_INFO "Marking TSC unstable due to %s\n", reason);
 		/* Change only the rating, when not registered */
 		if (clocksource_tsc.mult)
-			clocksource_change_rating(&clocksource_tsc, 0);
-		else
+			clocksource_mark_unstable(&clocksource_tsc);
+		else {
+			clocksource_tsc.flags |= CLOCK_SOURCE_UNSTABLE;
 			clocksource_tsc.rating = 0;
+		}
 	}
 }
 

trunk/include/linux/clocksource.h

@@ -277,6 +277,7 @@ extern struct clocksource* clocksource_get_next(void);
 extern void clocksource_change_rating(struct clocksource *cs, int rating);
 extern void clocksource_resume(void);
 extern struct clocksource * __init __weak clocksource_default_clock(void);
+extern void clocksource_mark_unstable(struct clocksource *cs);
 
 #ifdef CONFIG_GENERIC_TIME_VSYSCALL
 extern void update_vsyscall(struct timespec *ts, struct clocksource *c);

trunk/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;