Re: [PATCH] perf tools: Don't set leader if parser doesn't collect an evsel

[Wangnan (F)]

On 2015/9/2 13:57, åæéå / HIRAMATUïMASAMI wrote:
> > From: Wang Nan [mailto:wangnan0@xxxxxxxxxx]
> >
> > Similar to patch 'perf tools: Don't set cmdline_group_boundary if no
> > evsel is collected', in case when parser collects no evsel (at this
> > point it shouldn't happen), parse_events__set_leader() is not safe.
> >
> > This patch checks list_empty becore calling __perf_evlist__set_leader()
> > for safty reason.
> >
> > Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
> > Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
> > Cc: Alexei Starovoitov <ast@xxxxxxxxxxxx>
> > Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
> > Cc: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
> > Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
> > Cc: Zefan Li <lizefan@xxxxxxxxxx>
> > Cc: pi3orama@xxxxxxx
> > ---
> >
> > I'd like to queue this patch into my next pull request. Since it is not
> > a real bug, it may be dropped.
> >
> > ---
> >   tools/perf/util/parse-events.c | 3 +++
> >   1 file changed, 3 insertions(+)
> >
> > diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
> > index f2c0317..836d226 100644
> > --- a/tools/perf/util/parse-events.c
> > +++ b/tools/perf/util/parse-events.c
> > @@ -793,6 +793,9 @@ void parse_events__set_leader(char *name, struct list_head *list)
> >   {
> >   	struct perf_evsel *leader;
> >
> > +	if (list_empty(list))
> Would we need to warn/debug something here?

OK, let's add a WARN message here and other 2 places.

Thank you.

> Thank you,
>
> > +		return;
> > +
> >   	__perf_evlist__set_leader(list);
> >   	leader = list_entry(list->next, struct perf_evsel, node);
> >   	leader->group_name = name ? strdup(name) : NULL;
> > --
> > 1.8.3.4


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