tools/trace: Fix TypeError when format string contains %K or %U

Author: xingfeng2510

tools/trace.py

@@ -630,8 +630,8 @@ def print_event(self, bpf, cpu, data, size):
                 event = ct.cast(data, ct.POINTER(self.python_struct)).contents
                 if self.name not in event.comm:
                     return
-                values = map(lambda i: getattr(event, "v%d" % i),
-                             range(0, len(self.values)))
+                values = list(map(lambda i: getattr(event, "v%d" % i),
+                             range(0, len(self.values))))
                 msg = self._format_message(bpf, event.tgid, values)
                 if self.msg_filter and self.msg_filter not in msg:
                     return