--- x/net/bluetooth/hci_sync.c
+++ y/net/bluetooth/hci_sync.c
@@ -862,14 +862,17 @@ bool hci_cmd_sync_dequeue_once(struct hc
 			       void *data, hci_cmd_sync_work_destroy_t destroy)
 {
 	struct hci_cmd_sync_work_entry *entry;
+	bool ret = false;
 
-	entry = hci_cmd_sync_lookup_entry(hdev, func, data, destroy);
-	if (!entry)
-		return false;
+	mutex_lock(&hdev->cmd_sync_work_lock);
+	entry = _hci_cmd_sync_lookup_entry(hdev, func, data, destroy);
+	if (entry) {
+		_hci_cmd_sync_cancel_entry(hdev, entry, -ECANCELED);
+		ret = true;
+	}
+	mutex_unlock(&hdev->cmd_sync_work_lock);
 
-	hci_cmd_sync_cancel_entry(hdev, entry);
-
-	return true;
+	return ret;
 }
 EXPORT_SYMBOL(hci_cmd_sync_dequeue_once);