1 files changed, 6 insertions, 5 deletions

diff --git a/kernel/locking/rtmutex_common.h b/kernel/locking/rtmutex_common.h
index 68686b3ec3c1..d1d62f942be2 100644
--- a/kernel/locking/rtmutex_common.h
+++ b/kernel/locking/rtmutex_common.h
@@ -52,12 +52,13 @@ static inline int rt_mutex_has_waiters(struct rt_mutex *lock)
 static inline struct rt_mutex_waiter *
 rt_mutex_top_waiter(struct rt_mutex *lock)
 {
-        struct rt_mutex_waiter *w;
-
-        w = rb_entry(lock->waiters.rb_leftmost,
-                     struct rt_mutex_waiter, tree_entry);
-        BUG_ON(w->lock != lock);
+        struct rb_node *leftmost = rb_first_cached(&lock->waiters);
+        struct rt_mutex_waiter *w = NULL;
 
+        if (leftmost) {
+                w = rb_entry(leftmost, struct rt_mutex_waiter, tree_entry);
+                BUG_ON(w->lock != lock);
+        }
         return w;
 }