Commit 1dd349ab authored Nov 28, 2016 by Steven Rostedt (Red Hat) Committed by Steven Rostedt Dec 09, 2016

tracing: Do not start benchmark on boot up



Trace events are enabled very early on boot up via the boot command line
parameter. The benchmark tool creates a new thread to perform the trace
event benchmarking. But at start up, it is called before scheduling is set
up and because it creates a new thread before the init thread is created,
this crashes the kernel.

Have the benchmark fail to register when started via the kernel command
line.

Also, since the registering of a tracepoint now can handle failure cases,
return -ENOMEM instead of warning if the thread cannot be created.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

parent 8cf868af

kernel/trace/trace_benchmark.c

+11 −1

Original line number	Diff line number	Diff line
		@@ -166,9 +166,18 @@ static int benchmark_event_kthread(void *arg)
		*/
		int trace_benchmark_reg(void)
		{
		if (system_state != SYSTEM_RUNNING) {
		pr_warning("trace benchmark cannot be started via kernel command line\n");
		return -EBUSY;
		}

		bm_event_thread = kthread_run(benchmark_event_kthread,
		NULL, "event_benchmark");
		WARN_ON(!bm_event_thread);
		if (!bm_event_thread) {
		pr_warning("trace benchmark failed to create kernel thread\n");
		return -ENOMEM;
		}

		return 0;
		}

		@@ -183,6 +192,7 @@ void trace_benchmark_unreg(void)
		return;

		kthread_stop(bm_event_thread);
		bm_event_thread = NULL;

		strcpy(bm_str, "START");
		bm_total = 0;