linux-kernel - [PATCH 01/12] perf: Use tracepoint_synchronize_unregister() to flush any pending tracepoint call

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Message-Id: <1280707993-6599-2-git-send-regression-fweisbec@gmail.com>
Date:	Mon,  2 Aug 2010 02:13:02 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>,
	Steven Rostedt <rostedt@...dmis.org>,
	Li Zefan <lizf@...fujitsu.com>
Subject: [PATCH 01/12] perf: Use tracepoint_synchronize_unregister() to flush any pending tracepoint call

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@...il.com>
Cc: Ingo Molnar <mingo@...e.hu>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Li Zefan <lizf@...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

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