common: update comment

diff --git a/common.cc b/common.cc
index bbb30539a8bd36710d9837614c2823b4f1ed3894..f8df1335b00cbe57001d4efacea2191134a4653c 100644 (file)
--- a/common.cc
+++ b/common.cc
@@ -77,6 +77,8 @@ void model_assert(bool expr, const char *file, int line)
  * output much data, we will need to buffer it in user-space during execution.
  * This also means that if ModelChecker decides not to print an execution, it
  * should promptly clear the pipe.
+ *
+ * This function should only be called once.
  */
 void redirect_output()
 {