diff --git a/libwvdrmengine/cdm/core/src/cdm_engine.cpp b/libwvdrmengine/cdm/core/src/cdm_engine.cpp
index c7bc47d4..da3a1b71 100644
--- a/libwvdrmengine/cdm/core/src/cdm_engine.cpp
+++ b/libwvdrmengine/cdm/core/src/cdm_engine.cpp
@@ -1655,51 +1655,54 @@ void CdmEngine::OnTimerEvent() {
   bool is_initial_usage_update = false;
   bool is_usage_update_needed = false;
 
-  AutoLock lock(session_map_lock_);
-  CdmSessionList sessions;
-  session_map_.GetSessionList(sessions);
-
-  while (!sessions.empty()) {
-    is_initial_usage_update =
-        is_initial_usage_update || sessions.front()->is_initial_usage_update();
-    is_usage_update_needed =
-        is_usage_update_needed || sessions.front()->is_usage_update_needed();
-
-    sessions.front()->OnTimerEvent(usage_update_period_expired);
-    sessions.pop_front();
-  }
-
-  if (is_usage_update_needed &&
-      (usage_update_period_expired || is_initial_usage_update)) {
-    bool has_usage_been_updated = false;
-
-    // Session list may have changed. Rebuild.
+  {
+    AutoLock lock(session_map_lock_);
+    CdmSessionList sessions;
     session_map_.GetSessionList(sessions);
 
-    for (CdmSessionList::iterator iter = sessions.begin();
-         iter != sessions.end(); ++iter) {
-      (*iter)->reset_usage_flags();
-      switch ((*iter)->get_usage_support_type()) {
-        case kUsageEntrySupport:
-          if ((*iter)->has_provider_session_token()) {
-            (*iter)->UpdateUsageEntryInformation();
-          }
-          break;
-        case kUsageTableSupport:
-          if (!has_usage_been_updated) {
-            // usage is updated for all sessions so this needs to be
-            // called only once per update usage information period
-            CdmResponseType status = (*iter)->UpdateUsageTableInformation();
-            if (NO_ERROR != status) {
-              LOGW("Update usage information failed: %d", status);
-            } else {
-              has_usage_been_updated = true;
+    while (!sessions.empty()) {
+      is_initial_usage_update =
+          is_initial_usage_update ||
+          sessions.front()->is_initial_usage_update();
+      is_usage_update_needed =
+          is_usage_update_needed || sessions.front()->is_usage_update_needed();
+
+      sessions.front()->OnTimerEvent(usage_update_period_expired);
+      sessions.pop_front();
+    }
+
+    if (is_usage_update_needed &&
+        (usage_update_period_expired || is_initial_usage_update)) {
+      bool has_usage_been_updated = false;
+
+      // Session list may have changed. Rebuild.
+      session_map_.GetSessionList(sessions);
+
+      for (CdmSessionList::iterator iter = sessions.begin();
+           iter != sessions.end(); ++iter) {
+        (*iter)->reset_usage_flags();
+        switch ((*iter)->get_usage_support_type()) {
+          case kUsageEntrySupport:
+            if ((*iter)->has_provider_session_token()) {
+              (*iter)->UpdateUsageEntryInformation();
             }
-          }
-          break;
-        default:
-          // Ignore
-          break;
+            break;
+          case kUsageTableSupport:
+            if (!has_usage_been_updated) {
+              // usage is updated for all sessions so this needs to be
+              // called only once per update usage information period
+              CdmResponseType status = (*iter)->UpdateUsageTableInformation();
+              if (NO_ERROR != status) {
+                LOGW("Update usage information failed: %d", status);
+              } else {
+                has_usage_been_updated = true;
+              }
+            }
+            break;
+          default:
+            // Ignore
+            break;
+        }
       }
     }
   }