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SubjectRe: ftrace/perf_event leak
On Wed, Sep 01, 2010 at 01:02:57PM +0200, Peter Zijlstra wrote:
> On Wed, 2010-09-01 at 13:38 +0300, Avi Kivity wrote:
> > On 09/01/2010 12:38 PM, Li Zefan wrote:
> > >
> > > Then try this:
> >
> > Tested-by: Avi Kivity <avi@redhat.com>
> >
>
> Thanks, queued as:
>
> ---
> Subject: perf, trace: Fix module leak
> From: Li Zefan <lizf@cn.fujitsu.com>
> Date: Wed Sep 01 12:58:43 CEST 2010
>
> Commit 1c024eca (perf, trace: Optimize tracepoints by using
> per-tracepoint-per-cpu hlist to track events) caused a module refcount
> leak.
>
> Tested-by: Avi Kivity <avi@redhat.com>
> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
> LKML-Reference: <4C7E1F12.8030304@cn.fujitsu.com>
> ---
> kernel/trace/trace_event_perf.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> Index: linux-2.6/kernel/trace/trace_event_perf.c
> ===================================================================
> --- linux-2.6.orig/kernel/trace/trace_event_perf.c
> +++ linux-2.6/kernel/trace/trace_event_perf.c
> @@ -91,6 +91,8 @@ int perf_trace_init(struct perf_event *p
> tp_event->class && tp_event->class->reg &&
> try_module_get(tp_event->mod)) {
> ret = perf_trace_event_init(tp_event, p_event);
> + if (ret)
> + module_put(tp_event->mod);
> break;
> }
> }
> @@ -147,6 +149,7 @@ void perf_trace_destroy(struct perf_even
> }
> }
> out:
> + module_put(tp_event->mod);
> mutex_unlock(&event_mutex);
> }
>
>



Thanks for fixing this.

However, can we split this in two patches to ease the backport?

The lack of a module_put() after perf_trace_init() failure is there for a while
(the backport needs to start in 2.6.32).

But the lack of a module_put in the destroy path needs a .35 backport only.



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