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authorWang Nan <wangnan0@huawei.com>2016-02-05 17:01:30 +0300
committerArnaldo Carvalho de Melo <acme@redhat.com>2016-02-12 23:27:48 +0300
commit5141d7350d3d8a12f1f76b1015b937f14d2b97e2 (patch)
tree49087b9f3b0428d509bb62fd821576cf12568196
parent2146afc6b45b3f1b967f5605d4e6d97dd9e31061 (diff)
downloadlinux-5141d7350d3d8a12f1f76b1015b937f14d2b97e2.tar.xz
perf data: Fix releasing event_class
A new patch in libbabeltrace [1] reveals a object leak problem in 'perf data' CTF support: perf code never releases the event_class which is allocated in add_event() and stored in evsel's private field. If libbabeltrace has the above patch applied, leaking event_class prevents the writer from being destroyed and flushing metadata. For example: $ perf record ls perf.data [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.012 MB perf.data (12 samples) ] $ perf data convert --to-ctf ./out.ctf [ perf data convert: Converted 'perf.data' into CTF data './out.ctf' ] [ perf data convert: Converted and wrote 0.000 MB (12 samples) ] $ cat ./out.ctf/metadata $ ls -l ./out.ctf/metadata -rw-r----- 1 w00229757 mm 0 Jan 27 10:49 ./out.ctf/metadata The correct result should be: ... $ cat ./out.ctf/metadata /* CTF 1.8 */ trace { [SNIP] $ ls -l ./out.ctf/metadata -rw-r----- 1 w00229757 mm 2446 Jan 27 10:52 ./out.ctf/metadata The full story is: Patch [1] of babeltrace redesigns its reference counting scheme. In that patch: * writer <- trace (bt_ctf_writer_create) * trace <- stream_class (bt_ctf_trace_add_stream_class) * stream_class <- event_class (bt_ctf_stream_class_add_event_class) ('<-' means 'is a parent of') Holding of event_class causes reference count of corresponding 'writer' to increase through parent chain. Perf expects that 'writer' is released (so metadata is flushed) through bt_ctf_writer_put() in ctf_writer__cleanup(). However, since it never releases event_class, the reference of 'writer' won't be dropped, so bt_ctf_writer_put() won't lead to the release of writer. Before this CTF patch, !(writer <- trace). Even with event_class leaking, the writer ends up being released. [1] https://github.com/efficios/babeltrace/commit/e6a8e8e4744633807083a077ff9f101eb97d9801 Signed-off-by: Wang Nan <wangnan0@huawei.com> Acked-by: Jiri Olsa <jolsa@kernel.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Brendan Gregg <brendan.d.gregg@gmail.com> Cc: Cody P Schafer <dev@codyps.com> Cc: He Kuang <hekuang@huawei.com> Cc: Jeremie Galarneau <jeremie.galarneau@efficios.com> Cc: Kirill Smelkov <kirr@nexedi.com> Cc: Li Zefan <lizefan@huawei.com> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Zefan Li <lizefan@huawei.com> Cc: pi3orama@163.com Link: http://lkml.kernel.org/r/1454680939-24963-6-git-send-email-wangnan0@huawei.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
-rw-r--r--tools/perf/util/data-convert-bt.c18
1 files changed, 18 insertions, 0 deletions
diff --git a/tools/perf/util/data-convert-bt.c b/tools/perf/util/data-convert-bt.c
index 34cd1e4039d3..b722e57d5a87 100644
--- a/tools/perf/util/data-convert-bt.c
+++ b/tools/perf/util/data-convert-bt.c
@@ -858,6 +858,23 @@ static int setup_events(struct ctf_writer *cw, struct perf_session *session)
return 0;
}
+static void cleanup_events(struct perf_session *session)
+{
+ struct perf_evlist *evlist = session->evlist;
+ struct perf_evsel *evsel;
+
+ evlist__for_each(evlist, evsel) {
+ struct evsel_priv *priv;
+
+ priv = evsel->priv;
+ bt_ctf_event_class_put(priv->event_class);
+ zfree(&evsel->priv);
+ }
+
+ perf_evlist__delete(evlist);
+ session->evlist = NULL;
+}
+
static int setup_streams(struct ctf_writer *cw, struct perf_session *session)
{
struct ctf_stream **stream;
@@ -1171,6 +1188,7 @@ int bt_convert__perf2ctf(const char *input, const char *path, bool force)
(double) c.events_size / 1024.0 / 1024.0,
c.events_count);
+ cleanup_events(session);
perf_session__delete(session);
ctf_writer__cleanup(cw);