From 05ce5818adee8f8efd0a5ca0d900a6789012516b Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Tue, 24 Mar 2009 00:18:31 -0400 Subject: [PATCH] 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 --- kernel/trace/ftrace.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 7847806eefe..c81a759fbf7 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); -- 2.41.1