LTTng » LTTng-tools

We have found a bug in LTTng regarding state of events after loading saved session configuration.

Steps to reproduce:
This requires a LTTng test application (hello-tp.h, hello-tp.c and hello.c) which can be found on LTTng web site: http://lttng.org/docs/#doc-tracing-your-own-user-application

1) Start test application
2) lttng create s1
3) lttng enable-event -u -s s1 hello_world:my_first_tracepoint -f '$ctx.procname "hello*"'
4) lttng enable-event -u -s s1 -c channel0 hello_world:my_first_tracepoint
5) lttng disable-event -u -s s1 -c channel0 -a
6) lttng enable-event -u -s s1 -c channel0 hello_world:my_first_tracepoint
7) lttng list s1
Tracing session s1: [inactive]
Trace path: /root/lttng-traces/s1-20000101-223220
Live timer interval (usec): 0

= Domain: UST global ===

Buffer type: per UID

Channels:
-------------
- channel0: [enabled]

Attributes:
overwrite mode: 0
subbufers size: 131072
number of subbufers: 4
switch timer interval: 0
read timer interval: 0
trace file count: 0
trace file size (bytes): 0
output: mmap()

Events:
hello_world:my_first_tracepoint (type: tracepoint) [enabled]
hello_world:my_first_tracepoint (type: tracepoint) [disabled] [with filter]

Note that first event is enabled which is correct.

8) lttng save
9) lttng destroy
10) lttng load
11) lttng list s1
Tracing session s1: [inactive]
Trace path: /root/lttng-traces/s1-20000101-223220
Live timer interval (usec): 0

=== Domain: UST global ===

Buffer type: per UID

Channels:
-------------
- channel0: [enabled]

Attributes:
overwrite mode: 0
subbufers size: 131072
number of subbufers: 4
switch timer interval: 0
read timer interval: 0
trace file count: 0
trace file size (bytes): 0
output: mmap()

Events:
hello_world:my_first_tracepoint (type: tracepoint) [disabled] [with filter]
hello_world:my_first_tracepoint (type: tracepoint) [disabled]

Bug! All events are disabled!