Commit-ID: 5141d7350d3d8a12f1f76b1015b937f14d2b97e2
Gitweb: http://git.kernel.org/tip/5141d7350d3d8a12f1f76b1015b937f14d2b97e2
Author: Wang Nan <wangnan0@xxxxxxxxxx>
AuthorDate: Fri, 5 Feb 2016 14:01:30 +0000
Committer: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Fri, 12 Feb 2016 17:27:48 -0300
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@xxxxxxxxxx>
Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
Cc: Brendan Gregg <brendan.d.gregg@xxxxxxxxx>
Cc: Cody P Schafer <dev@xxxxxxxxxx>
Cc: He Kuang <hekuang@xxxxxxxxxx>
Cc: Jeremie Galarneau <jeremie.galarneau@xxxxxxxxxxxx>
Cc: Kirill Smelkov <kirr@xxxxxxxxxx>
Cc: Li Zefan <lizefan@xxxxxxxxxx>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Zefan Li <lizefan@xxxxxxxxxx>
Cc: pi3orama@xxxxxxx
Link: http://lkml.kernel.org/r/1454680939-24963-6-git-send-email-wangnan0@xxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
tools/perf/util/data-convert-bt.c | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/tools/perf/util/data-convert-bt.c b/tools/perf/util/data-convert-bt.c
index 34cd1e4..b722e57 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);
--
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