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* RT-Mutex-tester: scriptable tester for rt mutexes
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* started by Thomas Gleixner:
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* Copyright (C) 2006, Timesys Corp., Thomas Gleixner <tglx@timesys.com>
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#include <linux/kthread.h>
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#include <linux/export.h>
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#include <linux/sched.h>
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#include <linux/spinlock.h>
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#include <linux/sysdev.h>
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#include <linux/timer.h>
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#include <linux/freezer.h>
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#define MAX_RT_TEST_THREADS 8
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#define MAX_RT_TEST_MUTEXES 8
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static spinlock_t rttest_lock;
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static atomic_t rttest_event;
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struct test_thread_data {
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int mutexes[MAX_RT_TEST_MUTEXES];
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struct sys_device sysdev;
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static struct test_thread_data thread_data[MAX_RT_TEST_THREADS];
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static struct task_struct *threads[MAX_RT_TEST_THREADS];
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static struct rt_mutex mutexes[MAX_RT_TEST_MUTEXES];
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RTTEST_SCHEDOT, /* 1 Sched other, data = nice */
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RTTEST_SCHEDRT, /* 2 Sched fifo, data = prio */
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RTTEST_LOCK, /* 3 Lock uninterruptible, data = lockindex */
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RTTEST_LOCKNOWAIT, /* 4 Lock uninterruptible no wait in wakeup, data = lockindex */
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RTTEST_LOCKINT, /* 5 Lock interruptible, data = lockindex */
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RTTEST_LOCKINTNOWAIT, /* 6 Lock interruptible no wait in wakeup, data = lockindex */
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RTTEST_LOCKCONT, /* 7 Continue locking after the wakeup delay */
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RTTEST_UNLOCK, /* 8 Unlock, data = lockindex */
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/* 9, 10 - reserved for BKL commemoration */
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RTTEST_SIGNAL = 11, /* 11 Signal other test thread, data = thread id */
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RTTEST_RESETEVENT = 98, /* 98 Reset event counter */
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RTTEST_RESET = 99, /* 99 Reset all pending operations */
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static int handle_op(struct test_thread_data *td, int lockwakeup)
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int i, id, ret = -EINVAL;
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td->mutexes[td->opdata] = 1;
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td->event = atomic_add_return(1, &rttest_event);
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for (i = 0; i < MAX_RT_TEST_MUTEXES; i++) {
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if (td->mutexes[i] == 4) {
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rt_mutex_unlock(&mutexes[i]);
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case RTTEST_RESETEVENT:
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atomic_set(&rttest_event, 0);
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case RTTEST_LOCKNOWAIT:
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if (id < 0 || id >= MAX_RT_TEST_MUTEXES)
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td->event = atomic_add_return(1, &rttest_event);
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rt_mutex_lock(&mutexes[id]);
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td->event = atomic_add_return(1, &rttest_event);
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case RTTEST_LOCKINTNOWAIT:
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if (id < 0 || id >= MAX_RT_TEST_MUTEXES)
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td->event = atomic_add_return(1, &rttest_event);
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ret = rt_mutex_lock_interruptible(&mutexes[id], 0);
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td->event = atomic_add_return(1, &rttest_event);
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td->mutexes[id] = ret ? 0 : 4;
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return ret ? -EINTR : 0;
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if (id < 0 || id >= MAX_RT_TEST_MUTEXES || td->mutexes[id] != 4)
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td->event = atomic_add_return(1, &rttest_event);
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rt_mutex_unlock(&mutexes[id]);
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td->event = atomic_add_return(1, &rttest_event);
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* Schedule replacement for rtsem_down(). Only called for threads with
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* PF_MUTEX_TESTER set.
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* This allows us to have finegrained control over the event flow.
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void schedule_rt_mutex_test(struct rt_mutex *mutex)
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struct test_thread_data *td;
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/* We have to lookup the task */
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for (tid = 0; tid < MAX_RT_TEST_THREADS; tid++) {
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if (threads[tid] == current)
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BUG_ON(tid == MAX_RT_TEST_THREADS);
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td = &thread_data[tid];
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case RTTEST_LOCKNOWAIT:
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case RTTEST_LOCKINTNOWAIT:
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if (mutex != &mutexes[dat])
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if (td->mutexes[dat] != 1)
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td->mutexes[dat] = 2;
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td->event = atomic_add_return(1, &rttest_event);
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if (mutex != &mutexes[dat])
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if (td->mutexes[dat] != 2)
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td->mutexes[dat] = 3;
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td->event = atomic_add_return(1, &rttest_event);
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case RTTEST_LOCKNOWAIT:
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case RTTEST_LOCKINTNOWAIT:
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if (mutex != &mutexes[dat])
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if (td->mutexes[dat] != 2)
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td->mutexes[dat] = 1;
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td->event = atomic_add_return(1, &rttest_event);
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set_current_state(TASK_INTERRUPTIBLE);
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if (td->opcode > 0) {
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set_current_state(TASK_RUNNING);
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ret = handle_op(td, 1);
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set_current_state(TASK_INTERRUPTIBLE);
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if (td->opcode == RTTEST_LOCKCONT)
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/* Wait for the next command to be executed */
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/* Restore previous command and data */
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static int test_func(void *data)
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struct test_thread_data *td = data;
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current->flags |= PF_MUTEX_TESTER;
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allow_signal(SIGHUP);
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set_current_state(TASK_INTERRUPTIBLE);
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if (td->opcode > 0) {
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set_current_state(TASK_RUNNING);
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ret = handle_op(td, 0);
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set_current_state(TASK_INTERRUPTIBLE);
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/* Wait for the next command to be executed */
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if (signal_pending(current))
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flush_signals(current);
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if(kthread_should_stop())
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* sysfs_test_command - interface for test commands
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* @dev: thread reference
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* @buf: command for actual step
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* @count: length of buffer
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static ssize_t sysfs_test_command(struct sys_device *dev, struct sysdev_attribute *attr,
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const char *buf, size_t count)
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struct sched_param schedpar;
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struct test_thread_data *td;
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int op, dat, tid, ret;
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td = container_of(dev, struct test_thread_data, sysdev);
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/* strings from sysfs write are not 0 terminated! */
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if (count >= sizeof(cmdbuf))
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if (buf[count-1] == '\n')
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memcpy(cmdbuf, buf, count);
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if (sscanf(cmdbuf, "%d:%d", &op, &dat) != 2)
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schedpar.sched_priority = 0;
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ret = sched_setscheduler(threads[tid], SCHED_NORMAL, &schedpar);
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set_user_nice(current, 0);
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schedpar.sched_priority = dat;
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ret = sched_setscheduler(threads[tid], SCHED_FIFO, &schedpar);
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send_sig(SIGHUP, threads[tid], 0);
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wake_up_process(threads[tid]);
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* sysfs_test_status - sysfs interface for rt tester
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* @dev: thread to query
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* @buf: char buffer to be filled with thread status info
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static ssize_t sysfs_test_status(struct sys_device *dev, struct sysdev_attribute *attr,
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struct test_thread_data *td;
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struct task_struct *tsk;
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td = container_of(dev, struct test_thread_data, sysdev);
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tsk = threads[td->sysdev.id];
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spin_lock(&rttest_lock);
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curr += sprintf(curr,
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"O: %4d, E:%8d, S: 0x%08lx, P: %4d, N: %4d, B: %p, M:",
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td->opcode, td->event, tsk->state,
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(MAX_RT_PRIO - 1) - tsk->prio,
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(MAX_RT_PRIO - 1) - tsk->normal_prio,
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for (i = MAX_RT_TEST_MUTEXES - 1; i >=0 ; i--)
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curr += sprintf(curr, "%d", td->mutexes[i]);
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spin_unlock(&rttest_lock);
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curr += sprintf(curr, ", T: %p, R: %p\n", tsk,
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mutexes[td->sysdev.id].owner);
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static SYSDEV_ATTR(status, 0600, sysfs_test_status, NULL);
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static SYSDEV_ATTR(command, 0600, NULL, sysfs_test_command);
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static struct sysdev_class rttest_sysclass = {
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static int init_test_thread(int id)
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thread_data[id].sysdev.cls = &rttest_sysclass;
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thread_data[id].sysdev.id = id;
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threads[id] = kthread_run(test_func, &thread_data[id], "rt-test-%d", id);
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if (IS_ERR(threads[id]))
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return PTR_ERR(threads[id]);
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return sysdev_register(&thread_data[id].sysdev);
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static int init_rttest(void)
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spin_lock_init(&rttest_lock);
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for (i = 0; i < MAX_RT_TEST_MUTEXES; i++)
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rt_mutex_init(&mutexes[i]);
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ret = sysdev_class_register(&rttest_sysclass);
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for (i = 0; i < MAX_RT_TEST_THREADS; i++) {
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ret = init_test_thread(i);
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ret = sysdev_create_file(&thread_data[i].sysdev, &attr_status);
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ret = sysdev_create_file(&thread_data[i].sysdev, &attr_command);
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printk("Initializing RT-Tester: %s\n", ret ? "Failed" : "OK" );
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device_initcall(init_rttest);