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Subject[PATCH tracing/kprobes 3/6] ftrace: Fix trace_remove_event_call() to lock trace_event_mutex
Date
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@redhat.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Frank Ch. Eigler <fche@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Jason Baron <jbaron@redhat.com>
Cc: K.Prasad <prasad@linux.vnet.ibm.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tom Zanussi <tzanussi@gmail.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@redhat.com


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