linux-kernel - [PATCH tracing/kprobes 3/6] ftrace: Fix trace_remove_event_call() to lock trace_event

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Date:	Mon, 14 Sep 2009 16:49:12 -0400
From:	Masami Hiramatsu <mhiramat@...hat.com>
To:	Frederic Weisbecker <fweisbec@...il.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Ingo Molnar <mingo@...e.hu>,
	lkml <linux-kernel@...r.kernel.org>
Cc:	systemtap <systemtap@...rces.redhat.com>,
	DLE <dle-develop@...ts.sourceforge.net>,
	Masami Hiramatsu <mhiramat@...hat.com>,
	Jim Keniston <jkenisto@...ibm.com>,
	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Andi Kleen <ak@...ux.intel.com>,
	Christoph Hellwig <hch@...radead.org>,
	"Frank Ch. Eigler" <fche@...hat.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...e.hu>,
	Jason Baron <jbaron@...hat.com>,
	"K.Prasad" <prasad@...ux.vnet.ibm.com>,
	Lai Jiangshan <laijs@...fujitsu.com>,
	Li Zefan <lizf@...fujitsu.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Tom Zanussi <tzanussi@...il.com>
Subject: [PATCH tracing/kprobes 3/6] ftrace: Fix trace_remove_event_call() to
	lock trace_event_mutex

Lock not only event_mutex but also trace_event_mutex in
trace_remove_event_call() for protecting __unregister_ftrace_event().

Signed-off-by: Masami Hiramatsu <mhiramat@...hat.com>
Cc: Jim Keniston <jkenisto@...ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@...ibm.com>
Cc: Andi Kleen <ak@...ux.intel.com>
Cc: Christoph Hellwig <hch@...radead.org>
Cc: Frank Ch. Eigler <fche@...hat.com>
Cc: Frederic Weisbecker <fweisbec@...il.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Ingo Molnar <mingo@...e.hu>
Cc: Jason Baron <jbaron@...hat.com>
Cc: K.Prasad <prasad@...ux.vnet.ibm.com>
Cc: Lai Jiangshan <laijs@...fujitsu.com>
Cc: Li Zefan <lizf@...fujitsu.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Tom Zanussi <tzanussi@...il.com>
---

 kernel/trace/trace_events.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 38e82a5..a3d6bad 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -1055,6 +1055,9 @@ static void remove_subsystem_dir(const char *name)
 	}
 }
 
+/*
+ * Must be called under locking both of event_mutex and trace_event_mutex.
+ */
 static void __trace_remove_event_call(struct ftrace_event_call *call)
 {
 	ftrace_event_enable_disable(call, 0);
@@ -1071,7 +1074,9 @@ static void __trace_remove_event_call(struct ftrace_event_call *call)
 void trace_remove_event_call(struct ftrace_event_call *call)
 {
 	mutex_lock(&event_mutex);
+	down_write(&trace_event_mutex);
 	__trace_remove_event_call(call);
+	up_write(&trace_event_mutex);
 	mutex_unlock(&event_mutex);
 }
 


-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@...hat.com
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