1 files changed, 16 insertions, 6 deletions

diff --git a/utils/unittest/googletest/include/gtest/internal/gtest-linked_ptr.h b/utils/unittest/googletest/include/gtest/internal/gtest-linked_ptr.h
index 57147b4e8bef..36029422174f 100644
--- a/utils/unittest/googletest/include/gtest/internal/gtest-linked_ptr.h
+++ b/utils/unittest/googletest/include/gtest/internal/gtest-linked_ptr.h
@@ -105,25 +105,35 @@ class linked_ptr_internal {
   // framework.
 
   // Join an existing circle.
-  // L < g_linked_ptr_mutex
-  void join(linked_ptr_internal const* ptr) {
+  void join(linked_ptr_internal const* ptr)
+      GTEST_LOCK_EXCLUDED_(g_linked_ptr_mutex) {
     MutexLock lock(&g_linked_ptr_mutex);
 
     linked_ptr_internal const* p = ptr;
-    while (p->next_ != ptr) p = p->next_;
+    while (p->next_ != ptr) {
+      assert(p->next_ != this &&
+             "Trying to join() a linked ring we are already in. "
+             "Is GMock thread safety enabled?");
+      p = p->next_;
+    }
     p->next_ = this;
     next_ = ptr;
   }
 
   // Leave whatever circle we're part of.  Returns true if we were the
   // last member of the circle.  Once this is done, you can join() another.
-  // L < g_linked_ptr_mutex
-  bool depart() {
+  bool depart()
+      GTEST_LOCK_EXCLUDED_(g_linked_ptr_mutex) {
     MutexLock lock(&g_linked_ptr_mutex);
 
     if (next_ == this) return true;
     linked_ptr_internal const* p = next_;
-    while (p->next_ != this) p = p->next_;
+    while (p->next_ != this) {
+      assert(p->next_ != next_ &&
+             "Trying to depart() a linked ring we are not in. "
+             "Is GMock thread safety enabled?");
+      p = p->next_;
+    }
     p->next_ = next_;
     return false;
   }