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Bug #567
closedlttng-tools 2.2.0-rc2: enable-channel failure leaves session in suspicious state
Start date:
06/25/2013
Due date:
% Done:
100%
Estimated time:
Description
The session:
$ sudo -H lttng list pid
Tracing session pid: [active]
Trace path: net://131.132.32.77:5342/pid-20130620-161857 [data: 5343]
=== Domain: UST global ===
Buffer type: per PID
Channels:
-------------
- canalpid: [enabled]
Attributes:
overwrite mode: 0
subbufers size: 4096
number of subbufers: 4
switch timer interval: 0
read timer interval: 0
output: mmap()
Events:
* (type: tracepoint) [enabled]
$ sudo -H lttng enable-channel k1 -k --discard --subbuf-size 1024 --num-subbuf 8
PERROR [20531/20631]: ioctl kernel create channel: Invalid argument (in kernel_create_channel() at kernel.c:144)
Error: Channel k1: Kernel create channel failed (session pid)
Warning: Some command(s) went wrong
$ sudo -H lttng list pid
Tracing session pid: [active]
Trace path: net://131.132.32.77:5342/pid-20130620-161857 [data: 5343]
=== Domain: Kernel ===
Warning: No kernel channel
=== Domain: UST global ===
Buffer type: per PID
Channels:
-------------
- canalpid: [enabled]
Attributes:
overwrite mode: 0
subbufers size: 4096
number of subbufers: 4
switch timer interval: 0
read timer interval: 0
output: mmap()
Events:
* (type: tracepoint) [enabled]
It is highly suspicious that the session's listing should gain this after a failed enable-channel command:
=== Domain: Kernel === Warning: No kernel channel
The enable-channel error is the same for an inactive session. I also note that the failed enable-channel caused the kernel lttng-consumerd daemon to start. Also, the next command ends with an error:
$ sudo -H lttng stop Error: Stopping kernel trace failed
Despite the "error", the trace was nevertheless stopped. However, the user does not get the expected "Tracing stopped for session pid" message. Maybe the error should be downgraded to a warning?
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