LTTng » LTTng-tools

This bug was first identified by Avi Goren <avi@reduxio.com>.

# lttng create loop
Session loop-20130625-145624 created.
Traces will be written in /root/lttng-traces/loop-20130625-145624
# lttng enable-event -a -u --loglevel TRACE_ALERT
All UST events are enabled in channel channel0 for loglevel TRACE_ALERT
# lttng disable-event -a -u
All UST events are disabled in channel channel0
# lttng enable-event -a -u --loglevel TRACE_CRIT
All UST events are enabled in channel channel0 for loglevel TRACE_CRIT
# lttng list loop
(...)
    Events:
      * (loglevel: TRACE_CRIT (2)) (type: tracepoint) [enabled]
      * (loglevel: TRACE_ALERT (1)) (type: tracepoint) [disabled]
# lttng disable-event -a -u
(LTTng hangs here)

Remarkably, the session daemon remains very busy after the sudo kill command is issued, even though the trace has not even been started! It refuses to die (I sent Ctrl-C a few times from the shell that was running lttng-sessiond) and the system must be restarted.

Attached is the session daemon's log. Note the "Trace UST event * NOT found" that should not have occurred.