Re: [PATCH v3 2/9] perf tools: splice events onto evlist even on error

On Fri, Oct 25, 2019 at 08:47:12AM -0700, Ian Rogers wrote:

SNIP

event_pmu: PE_NAME opt_event_config
{
...
ALLOC_LIST(list);  // <--- where list gets allocated
...
https://github.com/torvalds/linux/blob/master/tools/perf/util/parse-events.y#L229

opt_event_config:
https://github.com/torvalds/linux/blob/master/tools/perf/util/parse-events.y#L510

So the parse_state is ending up with a list, however, parsing is
failing. If the list isn't adding to the evlist then it becomes a
leak. Splicing it onto the evlist allows the caller to clean this up
and avoids the leak. An alternate approach is to free the failed list
and not get the caller to clean up. A way to do this is to create an
evlist, splice the failed list onto it and then free it - which winds
up being fairly identical to this approach, and this approach is a
smaller change.

agreed, thanks for the all the details

jirka