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

From: Jiri Olsa <[email-masked]>
Date: Mon, 28 Oct 2019 22:06:37 +0100

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