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authorSteven Rostedt (Red Hat) <rostedt@goodmis.org>2016-11-28 13:17:25 -0500
committerSteven Rostedt <rostedt@goodmis.org>2016-12-09 09:14:00 -0500
commit1dd349ab74d278cee50fc24dc26c023f3b149642 (patch)
tree58adadd49877f222a88007c10dc35eb2e160a02f /kernel/trace/trace_benchmark.c
parent8cf868affdc459beee1a941df0cfaba1673740e3 (diff)
downloadlinux-1dd349ab74d278cee50fc24dc26c023f3b149642.tar.bz2
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>
Diffstat (limited to 'kernel/trace/trace_benchmark.c')
-rw-r--r--kernel/trace/trace_benchmark.c12
1 files changed, 11 insertions, 1 deletions
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;