[PATCH 34/57] perf scripting engines: Iterate on tep event arrays directly

Arnaldo Carvalho de Melo
2019-10-21T13:42:35Z

From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>

Instead of calling a useless (and broken) helper function to get the
next event of a tep event array, just get the array directly and iterate
over it.

Note, the broken part was from trace_find_next_event() which after this
will no longer be used, and can be removed.

Committer notes:

This fixes a segfault when generating python scripts from perf.data
files with multiple tracepoint events, i.e. the following use case is
fixed by this patch:

# perf record -e sched:* sleep 1
[ perf record: Woken up 31 times to write data ]
[ perf record: Captured and wrote 0.031 MB perf.data (9 samples) ]
# perf script -g python
Segmentation fault (core dumped)
#

Reported-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Tzvetomir Stoyanov <tstoyanov@vmware.com>
Cc: linux-trace-devel@vger.kernel.org
Link: http://lkml.kernel.org/r/20191017153733.630cd5eb@gandalf.local.home
Link: http://lore.kernel.org/lkml/20191017210636.061448713@goodmis.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/scripting-engines/trace-event-perl.c | 8 ++++++--
tools/perf/util/scripting-engines/trace-event-python.c | 9 +++++++--
2 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/tools/perf/util/scripting-engines/trace-event-perl.c b/tools/perf/util/scripting-engines/trace-event-perl.c
index 15961854ba67..741f040648b5 100644
--- a/tools/perf/util/scripting-engines/trace-event-perl.c
+++ b/tools/perf/util/scripting-engines/trace-event-perl.c
@@ -539,10 +539,11 @@ 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);
@@ -603,8 +604,11 @@ 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 5d341efc3237..93c03b39cd9c 100644
--- a/tools/perf/util/scripting-engines/trace-event-python.c
+++ b/tools/perf/util/scripting-engines/trace-event-python.c
@@ -1687,10 +1687,11 @@ 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);
@@ -1735,7 +1736,11 @@ 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, ");
--
2.21.0