[lttng-dev] Suspected Bug in lttng-tools

Shubham Kulkarni shubhambkul16 at gmail.com
Fri Dec 23 08:24:12 EST 2022


Hi,

I am entirely new to the lttng-tools and frankly not aware of anything.
But, one of our company's customer reported this issue, so I tried
reproducing. I was able to reproduce it with the version of lttng-tool
(2.12.4 - (Ta) Meilleure) installed on my Ubuntu 16.04 (
https://lttng.org/docs/v2.12/#doc-ubuntu-ppa).

Issue is, if I try to snapshot a session with an output filename containing
a ".", it fails. Steps I followed are given below :

*"*
root at MVIN00032:~# lttng create flightrecorder --snapshot
Snapshot session flightrecorder created.
Default snapshot output set to
/home/shubham/lttng-traces/flightrecorder-20221223-153147
Every channel enabled for this session will be set to mmap output and
default to overwrite mode.

root at MVIN00032:~# lttng enable-event -k -a
All Kernel events are enabled in channel channel0

root at MVIN00032:~# lttng start
Tracing started for session flightrecorder

root at MVIN00032:~# lttng -vvv snapshot record -s flightrecorder -n
*record.dump*
DEBUG1 - 15:32:15.173476719 [7159/7159]: LSM cmd type : 28 (in
send_session_msg() at lttng-ctl.c:128)
*Error: Create directory failed*
DEBUG1 - 15:32:15.197542565 [7159/7159]: Clean exit (in clean_exit() at
lttng.c:152)

root at MVIN00032:~# lttng -vvv snapshot record -s flightrecorder -n
*record_dump*
DEBUG1 - 15:32:24.013450964 [7442/7442]: LSM cmd type : 28 (in
send_session_msg() at lttng-ctl.c:128)
*Snapshot recorded successfully for session flightrecorder*

root at MVIN00032:~# lttng stop
Waiting for data availability
Tracing stopped for session flightrecorder

root at MVIN00032:~# lttng destroy
Session flightrecorder destroyed *"*
-----------------------------------------------------------------------------------------------------------------------------------------------------------

I tried the same with lttng-tools v2.9.5 (as one of my company's product
uses this version) under runqemu session, which worked fine for
'record.dump' & with lttng-tools v2.11.5 (another product uses this
version) failed with the same error. So, maybe in between these versions an
issue was introduced.

I am not sure whether this is the correct location to send this mail, but I
didn't find any solution on the Internet and I am not aware of lttng at
all. I was able to reproduce the issue with help from the internet, so
thought to report it via this mailing list.

Thanks,
Shubham
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