Sorry, forget to CC kernel mailing list... On 2015/9/2 14:49, Wang Nan wrote:
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 <wangn...@huawei.com> Cc: Arnaldo Carvalho de Melo <a...@redhat.com> Cc: Alexei Starovoitov <a...@plumgrid.com> Cc: Jiri Olsa <jo...@kernel.org> Cc: Masami Hiramatsu <masami.hiramatsu...@hitachi.com> Cc: Namhyung Kim <namhy...@kernel.org> Cc: Zefan Li <lize...@huawei.com> Cc: pi3or...@163.com --- Merge all 3 list_empty() test together into one patch. Add warning messages. Improve commit message. --- tools/perf/util/parse-events.c | 22 +++++++++++++++++++--- 1 file changed, 19 insertions(+), 3 deletions(-) diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c index d826e6f..069848d 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_printf("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 +1148,15 @@ 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)) {+ last = list_entry(data.list.prev, + struct perf_evsel, node); + last->cmdline_group_boundary = true; + } else + __WARN_printf("WARNING: event parser found nothing"); + 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 +1262,13 @@ 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 {
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