/*
   * RT-Mutex-tester: scriptable tester for rt mutexes
   *
   * started by Thomas Gleixner:
   *
   *  Copyright (C) 2006, Timesys Corp., Thomas Gleixner <tglx@timesys.com>
   *
   */

  #include <linux/device.h>

  #include <linux/kthread.h>

  #include <linux/export.h>

  #include <linux/sched.h>

  #include <linux/spinlock.h>

  #include <linux/timer.h>

  #include <linux/freezer.h>

  
  #include "rtmutex.h"
  
  #define MAX_RT_TEST_THREADS	8
  #define MAX_RT_TEST_MUTEXES	8
  
  static spinlock_t rttest_lock;
  static atomic_t rttest_event;
  
  struct test_thread_data {
  	int			opcode;
  	int			opdata;
  	int			mutexes[MAX_RT_TEST_MUTEXES];

  	int			event;

  	struct device		dev;

  };
  
  static struct test_thread_data thread_data[MAX_RT_TEST_THREADS];

  static struct task_struct *threads[MAX_RT_TEST_THREADS];

  static struct rt_mutex mutexes[MAX_RT_TEST_MUTEXES];
  
  enum test_opcodes {
  	RTTEST_NOP = 0,
  	RTTEST_SCHEDOT,		/* 1 Sched other, data = nice */
  	RTTEST_SCHEDRT,		/* 2 Sched fifo, data = prio */
  	RTTEST_LOCK,		/* 3 Lock uninterruptible, data = lockindex */
  	RTTEST_LOCKNOWAIT,	/* 4 Lock uninterruptible no wait in wakeup, data = lockindex */
  	RTTEST_LOCKINT,		/* 5 Lock interruptible, data = lockindex */
  	RTTEST_LOCKINTNOWAIT,	/* 6 Lock interruptible no wait in wakeup, data = lockindex */
  	RTTEST_LOCKCONT,	/* 7 Continue locking after the wakeup delay */
  	RTTEST_UNLOCK,		/* 8 Unlock, data = lockindex */

  	/* 9, 10 - reserved for BKL commemoration */
  	RTTEST_SIGNAL = 11,	/* 11 Signal other test thread, data = thread id */

  	RTTEST_RESETEVENT = 98,	/* 98 Reset event counter */
  	RTTEST_RESET = 99,	/* 99 Reset all pending operations */
  };
  
  static int handle_op(struct test_thread_data *td, int lockwakeup)
  {

  	int i, id, ret = -EINVAL;
  
  	switch(td->opcode) {
  
  	case RTTEST_NOP:
  		return 0;

  	case RTTEST_LOCKCONT:
  		td->mutexes[td->opdata] = 1;
  		td->event = atomic_add_return(1, &rttest_event);
  		return 0;
  
  	case RTTEST_RESET:
  		for (i = 0; i < MAX_RT_TEST_MUTEXES; i++) {
  			if (td->mutexes[i] == 4) {
  				rt_mutex_unlock(&mutexes[i]);
  				td->mutexes[i] = 0;
  			}
  		}

  		return 0;
  
  	case RTTEST_RESETEVENT:
  		atomic_set(&rttest_event, 0);
  		return 0;
  
  	default:
  		if (lockwakeup)
  			return ret;
  	}
  
  	switch(td->opcode) {
  
  	case RTTEST_LOCK:
  	case RTTEST_LOCKNOWAIT:
  		id = td->opdata;
  		if (id < 0 || id >= MAX_RT_TEST_MUTEXES)
  			return ret;
  
  		td->mutexes[id] = 1;
  		td->event = atomic_add_return(1, &rttest_event);
  		rt_mutex_lock(&mutexes[id]);
  		td->event = atomic_add_return(1, &rttest_event);
  		td->mutexes[id] = 4;
  		return 0;
  
  	case RTTEST_LOCKINT:
  	case RTTEST_LOCKINTNOWAIT:
  		id = td->opdata;
  		if (id < 0 || id >= MAX_RT_TEST_MUTEXES)
  			return ret;
  
  		td->mutexes[id] = 1;
  		td->event = atomic_add_return(1, &rttest_event);
  		ret = rt_mutex_lock_interruptible(&mutexes[id], 0);
  		td->event = atomic_add_return(1, &rttest_event);
  		td->mutexes[id] = ret ? 0 : 4;
  		return ret ? -EINTR : 0;
  
  	case RTTEST_UNLOCK:
  		id = td->opdata;
  		if (id < 0 || id >= MAX_RT_TEST_MUTEXES || td->mutexes[id] != 4)
  			return ret;
  
  		td->event = atomic_add_return(1, &rttest_event);
  		rt_mutex_unlock(&mutexes[id]);
  		td->event = atomic_add_return(1, &rttest_event);
  		td->mutexes[id] = 0;
  		return 0;

  	default:
  		break;
  	}
  	return ret;
  }
  
  /*
   * Schedule replacement for rtsem_down(). Only called for threads with
   * PF_MUTEX_TESTER set.
   *
   * This allows us to have finegrained control over the event flow.
   *
   */
  void schedule_rt_mutex_test(struct rt_mutex *mutex)
  {
  	int tid, op, dat;
  	struct test_thread_data *td;
  
  	/* We have to lookup the task */
  	for (tid = 0; tid < MAX_RT_TEST_THREADS; tid++) {
  		if (threads[tid] == current)
  			break;
  	}
  
  	BUG_ON(tid == MAX_RT_TEST_THREADS);
  
  	td = &thread_data[tid];
  
  	op = td->opcode;
  	dat = td->opdata;
  
  	switch (op) {
  	case RTTEST_LOCK:
  	case RTTEST_LOCKINT:
  	case RTTEST_LOCKNOWAIT:
  	case RTTEST_LOCKINTNOWAIT:
  		if (mutex != &mutexes[dat])
  			break;
  
  		if (td->mutexes[dat] != 1)
  			break;
  
  		td->mutexes[dat] = 2;
  		td->event = atomic_add_return(1, &rttest_event);
  		break;

  	default:
  		break;
  	}
  
  	schedule();
  
  
  	switch (op) {
  	case RTTEST_LOCK:
  	case RTTEST_LOCKINT:
  		if (mutex != &mutexes[dat])
  			return;
  
  		if (td->mutexes[dat] != 2)
  			return;
  
  		td->mutexes[dat] = 3;
  		td->event = atomic_add_return(1, &rttest_event);
  		break;
  
  	case RTTEST_LOCKNOWAIT:
  	case RTTEST_LOCKINTNOWAIT:
  		if (mutex != &mutexes[dat])
  			return;
  
  		if (td->mutexes[dat] != 2)
  			return;
  
  		td->mutexes[dat] = 1;
  		td->event = atomic_add_return(1, &rttest_event);
  		return;

  	default:
  		return;
  	}
  
  	td->opcode = 0;
  
  	for (;;) {
  		set_current_state(TASK_INTERRUPTIBLE);
  
  		if (td->opcode > 0) {
  			int ret;
  
  			set_current_state(TASK_RUNNING);
  			ret = handle_op(td, 1);
  			set_current_state(TASK_INTERRUPTIBLE);
  			if (td->opcode == RTTEST_LOCKCONT)
  				break;
  			td->opcode = ret;
  		}
  
  		/* Wait for the next command to be executed */
  		schedule();
  	}
  
  	/* Restore previous command and data */
  	td->opcode = op;
  	td->opdata = dat;
  }
  
  static int test_func(void *data)
  {
  	struct test_thread_data *td = data;
  	int ret;
  
  	current->flags |= PF_MUTEX_TESTER;

  	set_freezable();

  	allow_signal(SIGHUP);
  
  	for(;;) {
  
  		set_current_state(TASK_INTERRUPTIBLE);
  
  		if (td->opcode > 0) {
  			set_current_state(TASK_RUNNING);
  			ret = handle_op(td, 0);
  			set_current_state(TASK_INTERRUPTIBLE);
  			td->opcode = ret;
  		}
  
  		/* Wait for the next command to be executed */
  		schedule();

  		try_to_freeze();

  
  		if (signal_pending(current))
  			flush_signals(current);
  
  		if(kthread_should_stop())
  			break;
  	}
  	return 0;
  }
  
  /**
   * sysfs_test_command - interface for test commands
   * @dev:	thread reference
   * @buf:	command for actual step
   * @count:	length of buffer
   *
   * command syntax:
   *
   * opcode:data
   */

  static ssize_t sysfs_test_command(struct device *dev, struct device_attribute *attr,

  				  const char *buf, size_t count)

  {

  	struct sched_param schedpar;

  	struct test_thread_data *td;
  	char cmdbuf[32];

  	int op, dat, tid, ret;

  	td = container_of(dev, struct test_thread_data, dev);
  	tid = td->dev.id;

  
  	/* strings from sysfs write are not 0 terminated! */
  	if (count >= sizeof(cmdbuf))
  		return -EINVAL;
  
  	/* strip of 
  : */
  	if (buf[count-1] == '
  ')
  		count--;
  	if (count < 1)
  		return -EINVAL;
  
  	memcpy(cmdbuf, buf, count);
  	cmdbuf[count] = 0;
  
  	if (sscanf(cmdbuf, "%d:%d", &op, &dat) != 2)
  		return -EINVAL;
  
  	switch (op) {

  	case RTTEST_SCHEDOT:
  		schedpar.sched_priority = 0;
  		ret = sched_setscheduler(threads[tid], SCHED_NORMAL, &schedpar);
  		if (ret)
  			return ret;
  		set_user_nice(current, 0);
  		break;
  
  	case RTTEST_SCHEDRT:
  		schedpar.sched_priority = dat;
  		ret = sched_setscheduler(threads[tid], SCHED_FIFO, &schedpar);
  		if (ret)
  			return ret;
  		break;

  	case RTTEST_SIGNAL:
  		send_sig(SIGHUP, threads[tid], 0);
  		break;
  
  	default:
  		if (td->opcode > 0)
  			return -EBUSY;
  		td->opdata = dat;
  		td->opcode = op;
  		wake_up_process(threads[tid]);
  	}
  
  	return count;
  }
  
  /**
   * sysfs_test_status - sysfs interface for rt tester
   * @dev:	thread to query
   * @buf:	char buffer to be filled with thread status info
   */

  static ssize_t sysfs_test_status(struct device *dev, struct device_attribute *attr,

  				 char *buf)

  {
  	struct test_thread_data *td;

  	struct task_struct *tsk;

  	char *curr = buf;

  	int i;

  	td = container_of(dev, struct test_thread_data, dev);
  	tsk = threads[td->dev.id];

  
  	spin_lock(&rttest_lock);
  
  	curr += sprintf(curr,

  		"O: %4d, E:%8d, S: 0x%08lx, P: %4d, N: %4d, B: %p, M:",

  		td->opcode, td->event, tsk->state,
  			(MAX_RT_PRIO - 1) - tsk->prio,
  			(MAX_RT_PRIO - 1) - tsk->normal_prio,

  		tsk->pi_blocked_on);

  
  	for (i = MAX_RT_TEST_MUTEXES - 1; i >=0 ; i--)
  		curr += sprintf(curr, "%d", td->mutexes[i]);
  
  	spin_unlock(&rttest_lock);
  
  	curr += sprintf(curr, ", T: %p, R: %p
  ", tsk,

  			mutexes[td->dev.id].owner);

  
  	return curr - buf;
  }

  static DEVICE_ATTR(status, 0600, sysfs_test_status, NULL);
  static DEVICE_ATTR(command, 0600, NULL, sysfs_test_command);

  static struct bus_type rttest_subsys = {

  	.name = "rttest",

  	.dev_name = "rttest",

  };
  
  static int init_test_thread(int id)
  {

  	thread_data[id].dev.bus = &rttest_subsys;
  	thread_data[id].dev.id = id;

  
  	threads[id] = kthread_run(test_func, &thread_data[id], "rt-test-%d", id);
  	if (IS_ERR(threads[id]))
  		return PTR_ERR(threads[id]);

  	return device_register(&thread_data[id].dev);

  }
  
  static int init_rttest(void)
  {
  	int ret, i;
  
  	spin_lock_init(&rttest_lock);
  
  	for (i = 0; i < MAX_RT_TEST_MUTEXES; i++)
  		rt_mutex_init(&mutexes[i]);

  	ret = subsys_system_register(&rttest_subsys, NULL);

  	if (ret)
  		return ret;
  
  	for (i = 0; i < MAX_RT_TEST_THREADS; i++) {
  		ret = init_test_thread(i);
  		if (ret)
  			break;

  		ret = device_create_file(&thread_data[i].dev, &dev_attr_status);

  		if (ret)
  			break;

  		ret = device_create_file(&thread_data[i].dev, &dev_attr_command);

  		if (ret)
  			break;
  	}
  
  	printk("Initializing RT-Tester: %s
  ", ret ? "Failed" : "OK" );
  
  	return ret;
  }
  
  device_initcall(init_rttest);