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From: Mathieu Desnoyers on 2 Aug 2010 11:30
* Frederic Weisbecker (fweisbec(a)gmail.com) wrote:
> We use synchronize_sched() to ensure a tracepoint won't be called
> while/after we release the perf buffers it references.
>
> But the tracepoint API has its own API for that:
> tracepoint_synchronize_unregister(). Use it instead as it's
> self-explanatory and eases maintainance.
>
> Signed-off-by: Frederic Weisbecker <fweisbec(a)gmail.com>

Acked-by: Mathieu Desnoyers <mathieu.desnoyers(a)efficios.com>

Thanks!

Mathieu

> Cc: Ingo Molnar <mingo(a)elte.hu>
> Cc: Peter Zijlstra <a.p.zijlstra(a)chello.nl>
> Cc: Arnaldo Carvalho de Melo <acme(a)redhat.com>
> Cc: Mathieu Desnoyers <mathieu.desnoyers(a)polymtl.ca>
> Cc: Steven Rostedt <rostedt(a)goodmis.org>
> Cc: Li Zefan <lizf(a)cn.fujitsu.com>
> ---
> kernel/trace/trace_event_perf.c | 6 +++---
> 1 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
> index 2375165..000e6e8 100644
> --- a/kernel/trace/trace_event_perf.c
> +++ b/kernel/trace/trace_event_perf.c
> @@ -131,10 +131,10 @@ void perf_trace_destroy(struct perf_event *p_event)
> tp_event->class->reg(tp_event, TRACE_REG_PERF_UNREGISTER);
>
> /*
> - * Ensure our callback won't be called anymore. See
> - * tracepoint_probe_unregister() and __DO_TRACE().
> + * Ensure our callback won't be called anymore. The buffers
> + * will be freed after that.
> */
> - synchronize_sched();
> + tracepoint_synchronize_unregister();
>
> free_percpu(tp_event->perf_events);
> tp_event->perf_events = NULL;
> --
> 1.6.2.3
>

--
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com
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