linux-kernel - Re: [BUG] libtraceevent: perf script -g python segfaults

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Message-ID: <20191017153733.630cd5eb@gandalf.local.home>
Date:   Thu, 17 Oct 2019 15:37:33 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
Cc:     Tzvetomir Stoyanov <tstoyanov@...are.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [BUG] libtraceevent: perf script -g python segfaults

On Thu, 17 Oct 2019 16:28:32 -0300
Arnaldo Carvalho de Melo <arnaldo.melo@...il.com> wrote:

> Em Thu, Oct 17, 2019 at 02:41:14PM -0400, Steven Rostedt escreveu:
> > On Thu, 17 Oct 2019 14:38:41 -0400
> > Steven Rostedt <rostedt@...dmis.org> wrote:
> >   
> > >  struct tep_event *trace_find_next_event(struct tep_handle *pevent,
> > >  					struct tep_event *event)
> > >  {
> > > +	static struct tep_event **all_events;
> > >  	static int idx;
> > >  	int events_count;
> > > -	struct tep_event *all_events;  
> > 
> > If we are going to use static variables, let's make them all static and
> > optimize it a little more...  
> 
> I'll test it, but can't you have this somewhere else, i.e. at
> tep_handle perhaps?
> 
>

Or we can nuke the function entirely, it's a rather silly helper
anyway. Just do this:

-- Steve


diff --git a/tools/perf/util/scripting-engines/trace-event-perl.c b/tools/perf/util/scripting-engines/trace-event-perl.c
index b93f36b887b5..f1d5f564aa46 100644
--- a/tools/perf/util/scripting-engines/trace-event-perl.c
+++ b/tools/perf/util/scripting-engines/trace-event-perl.c
@@ -537,10 +537,11 @@ static int perl_stop_script(void)
 
 static int perl_generate_script(struct tep_handle *pevent, const char *outfile)
 {
+	int i, not_first, count, nr_events;
+	struct tep_event **all_events;
 	struct tep_event *event = NULL;
 	struct tep_format_field *f;
 	char fname[PATH_MAX];
-	int not_first, count;
 	FILE *ofp;
 
 	sprintf(fname, "%s.pl", outfile);
@@ -601,8 +602,11 @@ sub print_backtrace\n\
 }\n\n\
 ");
 
+	nr_events = tep_get_events_count(pevent);
+	all_events = tep_list_events(pevent, TEP_EVENT_SORT_ID);
 
-	while ((event = trace_find_next_event(pevent, event))) {
+	for (i = 0; all_events && i < nr_events; i++) {
+		event = all_events[i];
 		fprintf(ofp, "sub %s::%s\n{\n", event->system, event->name);
 		fprintf(ofp, "\tmy (");
 
diff --git a/tools/perf/util/scripting-engines/trace-event-python.c b/tools/perf/util/scripting-engines/trace-event-python.c
index 87ef16a1b17e..2a148a10d0de 100644
--- a/tools/perf/util/scripting-engines/trace-event-python.c
+++ b/tools/perf/util/scripting-engines/trace-event-python.c
@@ -1590,10 +1590,11 @@ static int python_stop_script(void)
 
 static int python_generate_script(struct tep_handle *pevent, const char *outfile)
 {
+	int i, not_first, count, nr_events;
+	struct tep_event **all_events;
 	struct tep_event *event = NULL;
 	struct tep_format_field *f;
 	char fname[PATH_MAX];
-	int not_first, count;
 	FILE *ofp;
 
 	sprintf(fname, "%s.py", outfile);
@@ -1638,7 +1639,11 @@ static int python_generate_script(struct tep_handle *pevent, const char *outfile
 	fprintf(ofp, "def trace_end():\n");
 	fprintf(ofp, "\tprint(\"in trace_end\")\n\n");
 
-	while ((event = trace_find_next_event(pevent, event))) {
+	nr_events = tep_get_events_count(pevent);
+	all_events = tep_list_events(pevent, TEP_EVENT_SORT_ID);
+
+	for (i = 0; all_events && i < nr_events; i++) {
+		event = all_events[i];
 		fprintf(ofp, "def %s__%s(", event->system, event->name);
 		fprintf(ofp, "event_name, ");
 		fprintf(ofp, "context, ");