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/*
* RT-Mutex-tester: scriptable tester for rt mutexes
*
* started by Thomas Gleixner:
*
* Copyright (C) 2006, Timesys Corp., Thomas Gleixner <tglx@timesys.com>
*
*/
#include <linux/kthread.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/spinlock.h>
#include <linux/sysdev.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 sys_device sysdev;
};

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 sys_device *dev, struct sysdev_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, sysdev);
tid = td->sysdev.id;

/* strings from sysfs write are not 0 terminated! */
if (count >= sizeof(cmdbuf))
return -EINVAL;

/* strip of \n: */
if (buf[count-1] == '\n')
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 sys_device *dev, struct sysdev_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, sysdev);
tsk = threads[td->sysdev.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\n", tsk,
mutexes[td->sysdev.id].owner);

return curr - buf;
}

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

static struct sysdev_class rttest_sysclass = {
.name = "rttest",
};

static int init_test_thread(int id)
{
thread_data[id].sysdev.cls = &rttest_sysclass;
thread_data[id].sysdev.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 sysdev_register(&thread_data[id].sysdev);
}

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 = sysdev_class_register(&rttest_sysclass);
if (ret)
return ret;

for (i = 0; i < MAX_RT_TEST_THREADS; i++) {
ret = init_test_thread(i);
if (ret)
break;
ret = sysdev_create_file(&thread_data[i].sysdev, &attr_status);
if (ret)
break;
ret = sysdev_create_file(&thread_data[i].sysdev, &attr_command);
if (ret)
break;
}

printk("Initializing RT-Tester: %s\n", ret ? "Failed" : "OK" );

return ret;
}

device_initcall(init_rttest);
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