clocksource: Call clocksource_change_rating() outside of watchdog_lock

The changes to the watchdog logic introduced a lock inversion between
watchdog_lock and clocksource_mutex. Change the rating outside of
watchdog_lock to avoid it.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 9 insertions, 2 deletions

diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index a1657b5fdeb9..02dc22d888fe 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -307,16 +307,23 @@ static void clocksource_watchdog_work(struct work_struct *work)
 {
         struct clocksource *cs, *tmp;
         unsigned long flags;
+        LIST_HEAD(unstable);
 
         spin_lock_irqsave(&watchdog_lock, flags);
         list_for_each_entry_safe(cs, tmp, &watchdog_list, wd_list)
                 if (cs->flags & CLOCK_SOURCE_UNSTABLE) {
                         list_del_init(&cs->wd_list);
-                        clocksource_change_rating(cs, 0);
+                        list_add(&cs->wd_list, &unstable);
                 }
         /* Check if the watchdog timer needs to be stopped. */
         clocksource_stop_watchdog();
-        spin_unlock(&watchdog_lock);
+        spin_unlock_irqrestore(&watchdog_lock, flags);
+
+        /* Needs to be done outside of watchdog lock */
+        list_for_each_entry_safe(cs, tmp, &unstable, wd_list) {
+                list_del_init(&cs->wd_list);
+                clocksource_change_rating(cs, 0);
+        }
 }
 
 #else /* CONFIG_CLOCKSOURCE_WATCHDOG */