[lttng-dev] Assertion tgt_fc failed when trying to trace callstack-user

[Francis Deslauriers]

Hi Evan,

It turns out it's a Babeltrace 2 bug. Here the fix: 
https://review.lttng.org/c/babeltrace/+/6257.

It should be merged into the master and stable-2.0 branches soon.


Thank you for reporting the issue,

Francis


On 8/4/21 3:55 AM, Evan Galea wrote:
> Hi Francis, thanks for your reply. As it turns out, running babeltrace 
> on the file worked and I'm able to read the traces. I am running 
> babeltrace 1.5.8, lttng 2.12.4, lttng-tools 2.12.x stable, and lttng 
> modules 5.8.0-63. I attached the trace of the file.
>
>
> On Mon, Aug 2, 2021 at 8:56 AM Francis Deslauriers 
> <francis.deslauriers at efficios.com 
> <mailto:francis.deslauriers at efficios.com>> wrote:
>
>     Hi Evan,
>
>     On 8/1/21 5:11 AM, Evan Galea via lttng-dev wrote:
>>     Hi there
>>
>>     Thanks for help on my previous issue. I was able to get
>>     callstack-user to work and see it in my traces. However, in order
>>     to get it to run I needed to enable-event --kernel all. Is it
>>     necessary to have all kernel events enabled to run
>>     callstack-user? Or is it just one specific event?
>>
>>     When I try to run it without enabling all kernel events the
>>     command is accepted and it runs but I get the following error
>>     when trying to view my traces:
>>
>>      (╯°□°)╯︵ ┻━┻ ctf-meta-update-value-storing-indexes.c:65:
>>     update_field_class_stored_value_index(): Assertion `tgt_fc` failed.
>>     Aborted (core dumped)
>>
>>     What does this error mean? Should I just continue to enable all
>>     kernel events?
>
>     It's a Babeltrace 2 error. Now, we need to find out if the root
>     cause is the LTTng kernel tracer or Babeltrace2 itself.
>
>     What is the "one specific event" you're enabling that seems to
>     cause this issue?
>
>     Do you have access to a Babeltrace 1.5 build? if so, could you try
>     to read that same trace using it?
>
>     Could you please share a small trace reproducing this issue?
>
>     What version of LTTng-tools, LTTng-Modules, and Babeltrace2 are
>     you using?
>
>
>     Cheers,
>
>     Francis
>
>>
>>     My current command setup, not sure if relevant
>>
>>     lttng create &&
>>     lttng enable-channel mychannel --subbuf-size 100000000
>>     lttng enable-event --kernel --all &&
>>     lttng add-context -u -t vpid -t vtid -t procname &&
>>     lttng add-context --kernel --type callstack-user &&
>>     lttng add-context --kernel --type callstack-kernel &&
>>     lttng enable-event --jul jello
>>
>>     again thank you for your time
>>
>>     Evan Galea
>>
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>
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