From: Steven Rostedt 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 --- kernel/trace/ftrace.c | 6 ++++++ 1 files changed, 6 insertions(+), 0 deletions(-) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 7847806..c81a759 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -2643,6 +2643,12 @@ int register_ftrace_graph(trace_func_graph_ret_t retfunc, mutex_lock(&ftrace_lock); + /* we currently allow only one tracer registered at a time */ + if (atomic_read(&ftrace_graph_active)) { + ret = -EBUSY; + goto out; + } + ftrace_suspend_notifier.notifier_call = ftrace_suspend_notifier_call; register_pm_notifier(&ftrace_suspend_notifier); -- 1.6.2 -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/