lttng enable-event misbehaves when multiple event types are specified
Inspection of the
enable_events.c code reveals that if the user specifies multiple event types as command options, all but the last one are ignored. A user could specify a list of event names followed by a list of event type options, expecting one-on-one correspondence between them. For example:
lttng enable-event eventone,eventtwo -k --probe probesymbol --function functionsymbol
is equivalent to:
lttng enable-event eventone -k --probe probesymbol lttng enable-event eventtwo -k --function functionsymbol
Currently the first command actually resolves to:
lttng enable-event eventone -k --function functionsymbol lttng enable-event eventtwo -k --function functionsymbol
Because allowing multiple event types as well as multiple event names is fraught with difficulties (e.g. what if the two lists are of different lengths?), it should probably be discouraged. Specification of multiple event types in a single enable-event command should be an error condition.
The same observation holds when multiple event types are combined with the
--all command option (i.e. '
lttng enable-event -k --all --syscall --tracepoint' is treated the same as '
lttng enable-event -k --all --tracepoint').