v4.19.13 snapshot.
diff --git a/kernel/trace/preemptirq_delay_test.c b/kernel/trace/preemptirq_delay_test.c
new file mode 100644
index 0000000..d8765c9
--- /dev/null
+++ b/kernel/trace/preemptirq_delay_test.c
@@ -0,0 +1,72 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Preempt / IRQ disable delay thread to test latency tracers
+ *
+ * Copyright (C) 2018 Joel Fernandes (Google) <joel@joelfernandes.org>
+ */
+
+#include <linux/trace_clock.h>
+#include <linux/delay.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/kernel.h>
+#include <linux/kthread.h>
+#include <linux/module.h>
+#include <linux/printk.h>
+#include <linux/string.h>
+
+static ulong delay = 100;
+static char test_mode[10] = "irq";
+
+module_param_named(delay, delay, ulong, S_IRUGO);
+module_param_string(test_mode, test_mode, 10, S_IRUGO);
+MODULE_PARM_DESC(delay, "Period in microseconds (100 uS default)");
+MODULE_PARM_DESC(test_mode, "Mode of the test such as preempt or irq (default irq)");
+
+static void busy_wait(ulong time)
+{
+ u64 start, end;
+ start = trace_clock_local();
+ do {
+ end = trace_clock_local();
+ if (kthread_should_stop())
+ break;
+ } while ((end - start) < (time * 1000));
+}
+
+static int preemptirq_delay_run(void *data)
+{
+ unsigned long flags;
+
+ if (!strcmp(test_mode, "irq")) {
+ local_irq_save(flags);
+ busy_wait(delay);
+ local_irq_restore(flags);
+ } else if (!strcmp(test_mode, "preempt")) {
+ preempt_disable();
+ busy_wait(delay);
+ preempt_enable();
+ }
+
+ return 0;
+}
+
+static int __init preemptirq_delay_init(void)
+{
+ char task_name[50];
+ struct task_struct *test_task;
+
+ snprintf(task_name, sizeof(task_name), "%s_test", test_mode);
+
+ test_task = kthread_run(preemptirq_delay_run, NULL, task_name);
+ return PTR_ERR_OR_ZERO(test_task);
+}
+
+static void __exit preemptirq_delay_exit(void)
+{
+ return;
+}
+
+module_init(preemptirq_delay_init)
+module_exit(preemptirq_delay_exit)
+MODULE_LICENSE("GPL v2");