1 files changed, 70 insertions, 0 deletions
diff --git a/tools/testing/selftests/livepatch/test_modules/test_klp_callbacks_busy.c b/tools/testing/selftests/livepatch/test_modules/test_klp_callbacks_busy.c
new file mode 100644
index 000000000000..133929e0ce8f
--- /dev/null
+++ b/tools/testing/selftests/livepatch/test_modules/test_klp_callbacks_busy.c
@@ -0,0 +1,70 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2018 Joe Lawrence <joe.lawrence@redhat.com>
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/workqueue.h>
+#include <linux/delay.h>
+
+/* load/run-time control from sysfs writer  */
+static bool block_transition;
+module_param(block_transition, bool, 0644);
+MODULE_PARM_DESC(block_transition, "block_transition (default=false)");
+
+static void busymod_work_func(struct work_struct *work);
+static DECLARE_WORK(work, busymod_work_func);
+static DECLARE_COMPLETION(busymod_work_started);
+
+static void busymod_work_func(struct work_struct *work)
+{
+	pr_info("%s enter\n", __func__);
+	complete(&busymod_work_started);
+
+	while (READ_ONCE(block_transition)) {
+		/*
+		 * Busy-wait until the sysfs writer has acknowledged a
+		 * blocked transition and clears the flag.
+		 */
+		msleep(20);
+	}
+
+	pr_info("%s exit\n", __func__);
+}
+
+static int test_klp_callbacks_busy_init(void)
+{
+	pr_info("%s\n", __func__);
+	schedule_work(&work);
+
+	/*
+	 * To synchronize kernel messages, hold the init function from
+	 * exiting until the work function's entry message has printed.
+	 */
+	wait_for_completion(&busymod_work_started);
+
+	if (!block_transition) {
+		/*
+		 * Serialize output: print all messages from the work
+		 * function before returning from init().
+		 */
+		flush_work(&work);
+	}
+
+	return 0;
+}
+
+static void test_klp_callbacks_busy_exit(void)
+{
+	WRITE_ONCE(block_transition, false);
+	flush_work(&work);
+	pr_info("%s\n", __func__);
+}
+
+module_init(test_klp_callbacks_busy_init);
+module_exit(test_klp_callbacks_busy_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Joe Lawrence <joe.lawrence@redhat.com>");
+MODULE_DESCRIPTION("Livepatch test: busy target module");