Messages in this thread Patch in this message | | | From | Wang Nan <> | Subject | [PATCH 01/27] perf tools: Don't write to evsel if parser doesn't collect evsel | Date | Sun, 6 Sep 2015 07:13:17 +0000 |
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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 <wangnan0@huawei.com> Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Alexei Starovoitov <ast@plumgrid.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Zefan Li <lizefan@huawei.com> Cc: pi3orama@163.com Link: https://lkml.kernel.org/n/1441176553-116129-1-git-send-email-wangnan0@huawei.com [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
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