linux-kernel - Re: [PATCH] perf data: Fix releasing event

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Message-ID: <20160128092639.GE2322@krava.brq.redhat.com>
Date:	Thu, 28 Jan 2016 10:26:39 +0100
From:	Jiri Olsa <jolsa@...hat.com>
To:	"Wangnan (F)" <wangnan0@...wei.com>
Cc:	Jiri Olsa <jolsa@...nel.org>, acme@...hat.com,
	linux-kernel@...r.kernel.org,
	Jérémie Galarneau 
	<jeremie.galarneau@...icios.com>, Zefan Li <lizefan@...wei.com>,
	pi3orama@....com
Subject: Re: [PATCH] perf data: Fix releasing event_class

On Thu, Jan 28, 2016 at 04:59:51PM +0800, Wangnan (F) wrote:
> Hi Jiri, What's your opinion on this patch?

> 
> Thank you.
> 
> On 2016/1/27 19:21, Wang Nan wrote:
> >A new patch of libbabeltrace [1] reveals a object leak problem in
> >perf data CTF support: perf code never release 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
> >prevent writer being destroied and flushing metadata. For example:

oops, missed this one.. sry.. nice feature ;-)

> >
> >  $ ./perf record ls
> >  Lowering default frequency rate to 500.
> >  Please consider tweaking /proc/sys/kernel/perf_event_max_sample_rate.
> >  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

SNIP

> >+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);

right, we missed that.. but we should also call free(priv) then

also I can't see also perf_evlist__delete being called..
not sure perf_session__delete will take care of that

thanks,
jirka