A little extra device_list tracing

synapse/handlers/device.py

@@ -597,16 +597,25 @@ class DeviceListEduUpdater(object):
                     # eventually become consistent.
                     return
                 except FederationDeniedError as e:
+                    opentracing.set_tag("error", True)
+                    opentracing.log_kv({"reason": "FederationDeniedError"})
                     logger.info(e)
                     return
-                except Exception:
+                except Exception as e:
                     # TODO: Remember that we are now out of sync and try again
                     # later
+                    opentracing.set_tag("error", True)
+                    opentracing.log_kv(
+                        {
+                            "message": "Exception raised by federation request",
+                            "exception": e,
+                        }
+                    )
                     logger.exception(
                         "Failed to handle device list update for %s", user_id
                     )
                     return
-
+                opentracing.log_kv({"result": result})
                 stream_id = result["stream_id"]
                 devices = result["devices"]