forked from luck/tmp_suning_uos_patched
function-graph: prevent more than one tracer registering
Impact: prevent crash due to multiple function graph tracers The function graph tracer can currently only handle a single tracer being registered. If another tracer registers with the function graph tracer it can crash the system. Signed-off-by: Steven Rostedt <srostedt@redhat.com>
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@ -2643,6 +2643,12 @@ int register_ftrace_graph(trace_func_graph_ret_t retfunc,
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mutex_lock(&ftrace_lock);
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/* we currently allow only one tracer registered at a time */
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if (atomic_read(&ftrace_graph_active)) {
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ret = -EBUSY;
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goto out;
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}
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ftrace_suspend_notifier.notifier_call = ftrace_suspend_notifier_call;
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register_pm_notifier(&ftrace_suspend_notifier);
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