// SPDX-License-Identifier: GPL-2.0-only

  #include <linux/module.h>
  #include <linux/kthread.h>
  
  /*
   * Any file that uses trace points, must include the header.
   * But only one file, must include the header by defining
   * CREATE_TRACE_POINTS first.  This will make the C code that
   * creates the handles for the trace points.
   */
  #define CREATE_TRACE_POINTS
  #include "trace-events-sample.h"

  static const char *random_strings[] = {
  	"Mother Goose",
  	"Snoopy",
  	"Gandalf",
  	"Frodo",
  	"One ring to rule them all"
  };

  
  static void simple_thread_func(int cnt)
  {

  	int array[6];
  	int len = cnt % 5;
  	int i;

  	set_current_state(TASK_INTERRUPTIBLE);
  	schedule_timeout(HZ);

  
  	for (i = 0; i < len; i++)
  		array[i] = i + 1;
  	array[i] = 0;

  	/* Silly tracepoints */

  	trace_foo_bar("hello", cnt, array, random_strings[len],

  		      current->cpus_ptr);

  	trace_foo_with_template_simple("HELLO", cnt);

  	trace_foo_bar_with_cond("Some times print", cnt);

  
  	trace_foo_with_template_cond("prints other times", cnt);
  
  	trace_foo_with_template_print("I have to be different", cnt);

  }
  
  static int simple_thread(void *arg)
  {
  	int cnt = 0;
  
  	while (!kthread_should_stop())
  		simple_thread_func(cnt++);
  
  	return 0;
  }
  
  static struct task_struct *simple_tsk;

  static struct task_struct *simple_tsk_fn;
  
  static void simple_thread_func_fn(int cnt)
  {
  	set_current_state(TASK_INTERRUPTIBLE);
  	schedule_timeout(HZ);
  
  	/* More silly tracepoints */
  	trace_foo_bar_with_fn("Look at me", cnt);

  	trace_foo_with_template_fn("Look at me too", cnt);

  }
  
  static int simple_thread_fn(void *arg)
  {
  	int cnt = 0;
  
  	while (!kthread_should_stop())
  		simple_thread_func_fn(cnt++);
  
  	return 0;
  }
  
  static DEFINE_MUTEX(thread_mutex);

  static int simple_thread_cnt;

  int foo_bar_reg(void)

  {

  	mutex_lock(&thread_mutex);
  	if (simple_thread_cnt++)
  		goto out;

  	pr_info("Starting thread for foo_bar_fn
  ");
  	/*
  	 * We shouldn't be able to start a trace when the module is
  	 * unloading (there's other locks to prevent that). But
  	 * for consistency sake, we still take the thread_mutex.
  	 */

  	simple_tsk_fn = kthread_run(simple_thread_fn, NULL, "event-sample-fn");

   out:

  	mutex_unlock(&thread_mutex);

  	return 0;

  }
  
  void foo_bar_unreg(void)
  {

  	mutex_lock(&thread_mutex);

  	if (--simple_thread_cnt)
  		goto out;
  
  	pr_info("Killing thread for foo_bar_fn
  ");

  	if (simple_tsk_fn)
  		kthread_stop(simple_tsk_fn);
  	simple_tsk_fn = NULL;

   out:

  	mutex_unlock(&thread_mutex);
  }

  
  static int __init trace_event_init(void)
  {
  	simple_tsk = kthread_run(simple_thread, NULL, "event-sample");
  	if (IS_ERR(simple_tsk))
  		return -1;
  
  	return 0;
  }
  
  static void __exit trace_event_exit(void)
  {
  	kthread_stop(simple_tsk);

  	mutex_lock(&thread_mutex);
  	if (simple_tsk_fn)
  		kthread_stop(simple_tsk_fn);
  	simple_tsk_fn = NULL;
  	mutex_unlock(&thread_mutex);

  }
  
  module_init(trace_event_init);
  module_exit(trace_event_exit);
  
  MODULE_AUTHOR("Steven Rostedt");
  MODULE_DESCRIPTION("trace-events-sample");
  MODULE_LICENSE("GPL");