[Dle-develop] [PATCH tracing/kprobes 3/6] ftrace: Fix trace_remove_event_call() to lock trace_event_mutex

[Masami H. <mhi...@re...>]

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 <mhi...@re...>
Cc: Jim Keniston <jke...@us...>
Cc: Ananth N Mavinakayanahalli <an...@in...>
Cc: Andi Kleen <ak...@li...>
Cc: Christoph Hellwig <hc...@in...>
Cc: Frank Ch. Eigler <fc...@re...>
Cc: Frederic Weisbecker <fwe...@gm...>
Cc: H. Peter Anvin <hp...@zy...>
Cc: Ingo Molnar <mi...@el...>
Cc: Jason Baron <jb...@re...>
Cc: K.Prasad <pr...@li...>
Cc: Lai Jiangshan <la...@cn...>
Cc: Li Zefan <li...@cn...>
Cc: Peter Zijlstra <pe...@in...>
Cc: Srikar Dronamraju <sr...@li...>
Cc: Steven Rostedt <ro...@go...>
Cc: Tom Zanussi <tza...@gm...>
---

 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: mhi...@re...