If parse_events__scanner() collects no entry, perf_evlist__last(evlist) is invalid.
Although it shouldn't happen at this point, before calling perf_evlist__last(), we should ensure the list is not empty for safety reason. There are 3 places need this checking: 1. Before setting cmdline_group_boundary; 2. Before __perf_evlist__set_leader(); 3. In foreach_evsel_in_last_glob. Signed-off-by: Wang Nan <[email protected]> Reviewed-by: Masami Hiramatsu <[email protected]> Cc: Arnaldo Carvalho de Melo <[email protected]> Cc: Alexei Starovoitov <[email protected]> Cc: Jiri Olsa <[email protected]> Cc: Namhyung Kim <[email protected]> Cc: Zefan Li <[email protected]> Cc: [email protected] Link: https://lkml.kernel.org/n/[email protected] [wangnan: Enforce the assumption that parser never collect empty list] --- tools/perf/util/parse-events.c | 23 ++++++++++++++++++++--- 1 file changed, 20 insertions(+), 3 deletions(-) diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c index 3840176..07ce501 100644 --- a/tools/perf/util/parse-events.c +++ b/tools/perf/util/parse-events.c @@ -793,6 +793,11 @@ 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; @@ -1143,10 +1148,16 @@ int parse_events(struct perf_evlist *evlist, const char *str, int entries = data.idx - evlist->nr_entries; struct perf_evsel *last; + if (list_empty(&data.list)) { + WARN_ONCE(true, "WARNING: event parser found nothing"); + return -1; + } + + last = list_entry(data.list.prev, struct perf_evsel, node); + last->cmdline_group_boundary = true; + perf_evlist__splice_list_tail(evlist, &data.list, entries); evlist->nr_groups += data.nr_groups; - last = perf_evlist__last(evlist); - last->cmdline_group_boundary = true; return 0; } @@ -1252,7 +1263,13 @@ foreach_evsel_in_last_glob(struct perf_evlist *evlist, struct perf_evsel *last = NULL; int err; - if (evlist->nr_entries > 0) + /* + * 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 (!list_empty(&evlist->entries)) last = perf_evlist__last(evlist); do { -- 2.1.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
