Upgrade to 4.4.50-rt62

[kvmfornfv.git] / kernel / kernel / time / clocksource.c

diff --git a/kernel/kernel/time/clocksource.c b/kernel/kernel/time/clocksource.c
index 1347882..b98810d 100644 (file)
--- a/kernel/kernel/time/clocksource.c
+++ b/kernel/kernel/time/clocksource.c
@@ -323,13 +323,42 @@ static void clocksource_enqueue_watchdog(struct clocksource *cs)
                /* cs is a watchdog. */
                if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS)
                        cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES;
+       }
+       spin_unlock_irqrestore(&watchdog_lock, flags);
+}
+
+static void clocksource_select_watchdog(bool fallback)
+{
+       struct clocksource *cs, *old_wd;
+       unsigned long flags;
+
+       spin_lock_irqsave(&watchdog_lock, flags);
+       /* save current watchdog */
+       old_wd = watchdog;
+       if (fallback)
+               watchdog = NULL;
+
+       list_for_each_entry(cs, &clocksource_list, list) {
+               /* cs is a clocksource to be watched. */
+               if (cs->flags & CLOCK_SOURCE_MUST_VERIFY)
+                       continue;
+
+               /* Skip current if we were requested for a fallback. */
+               if (fallback && cs == old_wd)
+                       continue;
+
                /* Pick the best watchdog. */
-               if (!watchdog || cs->rating > watchdog->rating) {
+               if (!watchdog || cs->rating > watchdog->rating)
                        watchdog = cs;
-                       /* Reset watchdog cycles */
-                       clocksource_reset_watchdog();
-               }
        }
+       /* If we failed to find a fallback restore the old one. */
+       if (!watchdog)
+               watchdog = old_wd;
+
+       /* If we changed the watchdog we need to reset cycles. */
+       if (watchdog != old_wd)
+               clocksource_reset_watchdog();
+
        /* Check if the watchdog timer needs to be started. */
        clocksource_start_watchdog();
        spin_unlock_irqrestore(&watchdog_lock, flags);
@@ -404,6 +433,7 @@ static void clocksource_enqueue_watchdog(struct clocksource *cs)
                cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES;
 }
 
+static void clocksource_select_watchdog(bool fallback) { }
 static inline void clocksource_dequeue_watchdog(struct clocksource *cs) { }
 static inline void clocksource_resume_watchdog(void) { }
 static inline int __clocksource_watchdog_kthread(void) { return 0; }
@@ -736,6 +766,7 @@ int __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq)
        clocksource_enqueue(cs);
        clocksource_enqueue_watchdog(cs);
        clocksource_select();
+       clocksource_select_watchdog(false);
        mutex_unlock(&clocksource_mutex);
        return 0;
 }
@@ -758,6 +789,7 @@ void clocksource_change_rating(struct clocksource *cs, int rating)
        mutex_lock(&clocksource_mutex);
        __clocksource_change_rating(cs, rating);
        clocksource_select();
+       clocksource_select_watchdog(false);
        mutex_unlock(&clocksource_mutex);
 }
 EXPORT_SYMBOL(clocksource_change_rating);
@@ -767,12 +799,12 @@ EXPORT_SYMBOL(clocksource_change_rating);
  */
 static int clocksource_unbind(struct clocksource *cs)
 {
-       /*
-        * I really can't convince myself to support this on hardware
-        * designed by lobotomized monkeys.
-        */
-       if (clocksource_is_watchdog(cs))
-               return -EBUSY;
+       if (clocksource_is_watchdog(cs)) {
+               /* Select and try to install a replacement watchdog. */
+               clocksource_select_watchdog(true);
+               if (clocksource_is_watchdog(cs))
+                       return -EBUSY;
+       }
 
        if (cs == curr_clocksource) {
                /* Select and try to install a replacement clock source */