From 854f736364c659046f066a98fed2fdb10a39577a Mon Sep 17 00:00:00 2001 From: Wang Nan 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 Cc: Alexei Starovoitov Cc: Brendan Gregg Cc: Daniel Borkmann Cc: David Ahern Cc: He Kuang Cc: Jiri Olsa Cc: Kaixu Xia Cc: Masami Hiramatsu Cc: Namhyung Kim Cc: Paul Mackerras Cc: Peter Zijlstra Cc: Zefan Li 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 --- 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); -- 2.39.5