From 1dd349ab74d278cee50fc24dc26c023f3b149642 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" Date: Mon, 28 Nov 2016 13:17:25 -0500 Subject: [PATCH] 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 --- kernel/trace/trace_benchmark.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/kernel/trace/trace_benchmark.c b/kernel/trace/trace_benchmark.c index f76d0416dd83..2bc7dc3e8ff8 100644 --- a/kernel/trace/trace_benchmark.c +++ b/kernel/trace/trace_benchmark.c @@ -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; -- 2.39.5