LTTng » LTTng-tools

--probe and --function instrumentation options allow for custom event names.
This has the effect of making it possible to successfully enabling multiple events with the same name but of different types.
For example:

lttng enable-event -k --function=sys_open sched_switch
lttng enable-event -k --probe=sys_read sched_switch
lttng enable-event -k sched_switch

I am not quite sure what approach we should take on this issue. The event name duplication seems problematic. The most straightforward solution is comparing the new event's name to already enabled names but it's incomplete because that would open the possibility of preventing the enabling of kernel tracepoints(e.g. sched_switch) by the prior enabling --probe/--function events.

An approach would be to prepend a string to the --probe/--function event names to make them unique.
We could also simply document this behaviour as it's probably impacting very few users

Any thoughts?