From 854f736364c659046f066a98fed2fdb10a39577a Mon Sep 17 00:00:00 2001
From: Wang Nan <wangnan0@huawei.com>
Date: Sun, 6 Sep 2015 07:13:17 +0000
Subject: [PATCH] perf tools: Don't assume that the parser returns non empty
evsel list
Don't blindly retrieve and use a last element in the lists returned by
parse_events__scanner(), as it may have collected no entries, i.e.
return an empty list.
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: David Ahern <dsahern@gmail.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kaixu Xia <xiakaixu@huawei.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1441523623-152703-2-git-send-email-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/parse-events.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index 0fde5293a38e..61c2bc20926d 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -827,6 +827,11 @@ void parse_events__set_leader(char *name, struct list_head *list)
{
struct perf_evsel *leader;
+ if (list_empty(list)) {
+ WARN_ONCE(true, "WARNING: failed to set leader: empty list");
+ return;
+ }
+
__perf_evlist__set_leader(list);
leader = list_entry(list->next, struct perf_evsel, node);
leader->group_name = name ? strdup(name) : NULL;
@@ -1176,6 +1181,11 @@ int parse_events(struct perf_evlist *evlist, const char *str,
if (!ret) {
struct perf_evsel *last;
+ if (list_empty(&data.list)) {
+ WARN_ONCE(true, "WARNING: event parser found nothing");
+ return -1;
+ }
+
perf_evlist__splice_list_tail(evlist, &data.list);
evlist->nr_groups += data.nr_groups;
last = perf_evlist__last(evlist);
@@ -1285,6 +1295,12 @@ foreach_evsel_in_last_glob(struct perf_evlist *evlist,
struct perf_evsel *last = NULL;
int err;
+ /*
+ * Don't return when list_empty, give func a chance to report
+ * error when it found last == NULL.
+ *
+ * So no need to WARN here, let *func do this.
+ */
if (evlist->nr_entries > 0)
last = perf_evlist__last(evlist);
--
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