tracing: Do a WARN_ON() if start_thread() in hwlat is called when thread exists

The start function of the hwlat tracer should never be called when the hwlat
thread already exists. If it is called, do a WARN_ON().

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

diff --git a/kernel/trace/trace_hwlat.c b/kernel/trace/trace_hwlat.c
index 2d9d36dd5fe7796791b7d616341caf20a0724758..688e48be7bb51e352d34f86c73ed40b45696dc11 100644 (file)
--- a/kernel/trace/trace_hwlat.c
+++ b/kernel/trace/trace_hwlat.c
@@ -354,7 +354,7 @@ static int start_kthread(struct trace_array *tr)
        struct task_struct *kthread;
        int next_cpu;
 
-       if (hwlat_kthread)
+       if (WARN_ON(hwlat_kthread))
                return 0;
 
        /* Just pick the first CPU on first iteration */