[tip:perf/probes] ftrace: Fix trace_remove_event_call() to lock trace_event_mutex

[tip-bot for Masami Hiramatsu]

Commit-ID:  4fead8e46fded93cc0d432ced774d9a3a8d21bad
Gitweb:     http://git.kernel.org/tip/4fead8e46fded93cc0d432ced774d9a3a8d21bad
Author:     Masami Hiramatsu <mhiramat@xxxxxxxxxx>
AuthorDate: Mon, 14 Sep 2009 16:49:12 -0400
Committer:  Frederic Weisbecker <fweisbec@xxxxxxxxx>
CommitDate: Thu, 17 Sep 2009 04:03:50 +0200

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() to protect __unregister_ftrace_event().

Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Acked-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Jim Keniston <jkenisto@xxxxxxxxxx>
Cc: Ananth N Mavinakayanahalli <ananth@xxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Cc: Frank Ch. Eigler <fche@xxxxxxxxxx>
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Jason Baron <jbaron@xxxxxxxxxx>
Cc: K.Prasad <prasad@xxxxxxxxxxxxxxxxxx>
Cc: Lai Jiangshan <laijs@xxxxxxxxxxxxxx>
Cc: Li Zefan <lizf@xxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx>
Cc: Tom Zanussi <tzanussi@xxxxxxxxx>
LKML-Reference: <20090914204912.18779.68734.stgit@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Frederic Weisbecker <fweisbec@xxxxxxxxx>
---
 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 83cc2c0..f85b0f1 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -1054,6 +1054,9 @@ 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);
@@ -1070,7 +1073,9 @@ 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);
 }
 
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