Commit 2aad1b76 authored Mar 30, 2009 by Steven Rostedt Committed by Ingo Molnar Apr 01, 2009

function-graph: allow unregistering twice



Impact: fix to permanent disabling of function graph tracer

There should be nothing to prevent a tracer from unregistering a
function graph callback more than once. This can simplify error paths.

But currently, the counter does not account for mulitple unregistering
of the function graph callback. If it happens, the function graph
tracer will be permanently disabled.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

parent 8b54e45b

kernel/trace/ftrace.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -2719,6 +2719,9 @@ void unregister_ftrace_graph(void)
		{
		mutex_lock(&ftrace_lock);

		if (!unlikely(atomic_read(&ftrace_graph_active)))
		goto out;

		atomic_dec(&ftrace_graph_active);
		unregister_trace_sched_switch(ftrace_graph_probe_sched_switch);
		ftrace_graph_return = (trace_func_graph_ret_t)ftrace_stub;
		@@ -2726,6 +2729,7 @@ void unregister_ftrace_graph(void)
		ftrace_shutdown(FTRACE_STOP_FUNC_RET);
		unregister_pm_notifier(&ftrace_suspend_notifier);

		out:
		mutex_unlock(&ftrace_lock);
		}

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