[PATCH 15/46] perf tools: Only validate is_pos for tracking evsels

Wang Nan
2016-02-26T09:33:17Z

is_pos only useful for tracking events (fork, mmap, exit, ...).
Perf collects those events through evsel with 'tracking' set.
Therefore, there's no need to validate every is_pos against
evlist->is_pos.

With this commit, kernel can safely put something at the end of
a record. For example, PERF_SAMPLE_TAILSIZE [1]. However, since
we have dropped TAILSIZE, this commit is not mandatory, just
making code robust if someone implements similar things in their
private kernel.

[1] http://lkml.kernel.org/g/1449063499-236703-1-git-send-email-wangnan0@huawei.com

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Signed-off-by: He Kuang <hekuang@huawei.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
---
tools/perf/util/evlist.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 86a0383..227950b 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -1277,8 +1277,15 @@ bool perf_evlist__valid_sample_type(struct perf_evlist *evlist)
return false;

evlist__for_each(evlist, pos) {
- if (pos->id_pos != evlist->id_pos ||
- pos->is_pos != evlist->is_pos)
+ if (pos->id_pos != evlist->id_pos)
+ return false;
+ /*
+ * Only tracking events needs is_pos. Those events are
+ * collected if evsel->tracking is selected.
+ * For other evsel, is_pos is useless, so skip
+ * validating them.
+ */
+ if (pos->tracking && pos->is_pos != evlist->is_pos)
return false;
}

--
1.8.3.4