linux/kernel/rtmutex-tester.c
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   1/*
   2 * RT-Mutex-tester: scriptable tester for rt mutexes
   3 *
   4 * started by Thomas Gleixner:
   5 *
   6 *  Copyright (C) 2006, Timesys Corp., Thomas Gleixner <tglx@timesys.com>
   7 *
   8 */
   9#include <linux/device.h>
  10#include <linux/kthread.h>
  11#include <linux/export.h>
  12#include <linux/sched.h>
  13#include <linux/sched/rt.h>
  14#include <linux/spinlock.h>
  15#include <linux/timer.h>
  16#include <linux/freezer.h>
  17#include <linux/stat.h>
  18
  19#include "rtmutex.h"
  20
  21#define MAX_RT_TEST_THREADS     8
  22#define MAX_RT_TEST_MUTEXES     8
  23
  24static spinlock_t rttest_lock;
  25static atomic_t rttest_event;
  26
  27struct test_thread_data {
  28        int                     opcode;
  29        int                     opdata;
  30        int                     mutexes[MAX_RT_TEST_MUTEXES];
  31        int                     event;
  32        struct device           dev;
  33};
  34
  35static struct test_thread_data thread_data[MAX_RT_TEST_THREADS];
  36static struct task_struct *threads[MAX_RT_TEST_THREADS];
  37static struct rt_mutex mutexes[MAX_RT_TEST_MUTEXES];
  38
  39enum test_opcodes {
  40        RTTEST_NOP = 0,
  41        RTTEST_SCHEDOT,         /* 1 Sched other, data = nice */
  42        RTTEST_SCHEDRT,         /* 2 Sched fifo, data = prio */
  43        RTTEST_LOCK,            /* 3 Lock uninterruptible, data = lockindex */
  44        RTTEST_LOCKNOWAIT,      /* 4 Lock uninterruptible no wait in wakeup, data = lockindex */
  45        RTTEST_LOCKINT,         /* 5 Lock interruptible, data = lockindex */
  46        RTTEST_LOCKINTNOWAIT,   /* 6 Lock interruptible no wait in wakeup, data = lockindex */
  47        RTTEST_LOCKCONT,        /* 7 Continue locking after the wakeup delay */
  48        RTTEST_UNLOCK,          /* 8 Unlock, data = lockindex */
  49        /* 9, 10 - reserved for BKL commemoration */
  50        RTTEST_SIGNAL = 11,     /* 11 Signal other test thread, data = thread id */
  51        RTTEST_RESETEVENT = 98, /* 98 Reset event counter */
  52        RTTEST_RESET = 99,      /* 99 Reset all pending operations */
  53};
  54
  55static int handle_op(struct test_thread_data *td, int lockwakeup)
  56{
  57        int i, id, ret = -EINVAL;
  58
  59        switch(td->opcode) {
  60
  61        case RTTEST_NOP:
  62                return 0;
  63
  64        case RTTEST_LOCKCONT:
  65                td->mutexes[td->opdata] = 1;
  66                td->event = atomic_add_return(1, &rttest_event);
  67                return 0;
  68
  69        case RTTEST_RESET:
  70                for (i = 0; i < MAX_RT_TEST_MUTEXES; i++) {
  71                        if (td->mutexes[i] == 4) {
  72                                rt_mutex_unlock(&mutexes[i]);
  73                                td->mutexes[i] = 0;
  74                        }
  75                }
  76                return 0;
  77
  78        case RTTEST_RESETEVENT:
  79                atomic_set(&rttest_event, 0);
  80                return 0;
  81
  82        default:
  83                if (lockwakeup)
  84                        return ret;
  85        }
  86
  87        switch(td->opcode) {
  88
  89        case RTTEST_LOCK:
  90        case RTTEST_LOCKNOWAIT:
  91                id = td->opdata;
  92                if (id < 0 || id >= MAX_RT_TEST_MUTEXES)
  93                        return ret;
  94
  95                td->mutexes[id] = 1;
  96                td->event = atomic_add_return(1, &rttest_event);
  97                rt_mutex_lock(&mutexes[id]);
  98                td->event = atomic_add_return(1, &rttest_event);
  99                td->mutexes[id] = 4;
 100                return 0;
 101
 102        case RTTEST_LOCKINT:
 103        case RTTEST_LOCKINTNOWAIT:
 104                id = td->opdata;
 105                if (id < 0 || id >= MAX_RT_TEST_MUTEXES)
 106                        return ret;
 107
 108                td->mutexes[id] = 1;
 109                td->event = atomic_add_return(1, &rttest_event);
 110                ret = rt_mutex_lock_interruptible(&mutexes[id], 0);
 111                td->event = atomic_add_return(1, &rttest_event);
 112                td->mutexes[id] = ret ? 0 : 4;
 113                return ret ? -EINTR : 0;
 114
 115        case RTTEST_UNLOCK:
 116                id = td->opdata;
 117                if (id < 0 || id >= MAX_RT_TEST_MUTEXES || td->mutexes[id] != 4)
 118                        return ret;
 119
 120                td->event = atomic_add_return(1, &rttest_event);
 121                rt_mutex_unlock(&mutexes[id]);
 122                td->event = atomic_add_return(1, &rttest_event);
 123                td->mutexes[id] = 0;
 124                return 0;
 125
 126        default:
 127                break;
 128        }
 129        return ret;
 130}
 131
 132/*
 133 * Schedule replacement for rtsem_down(). Only called for threads with
 134 * PF_MUTEX_TESTER set.
 135 *
 136 * This allows us to have finegrained control over the event flow.
 137 *
 138 */
 139void schedule_rt_mutex_test(struct rt_mutex *mutex)
 140{
 141        int tid, op, dat;
 142        struct test_thread_data *td;
 143
 144        /* We have to lookup the task */
 145        for (tid = 0; tid < MAX_RT_TEST_THREADS; tid++) {
 146                if (threads[tid] == current)
 147                        break;
 148        }
 149
 150        BUG_ON(tid == MAX_RT_TEST_THREADS);
 151
 152        td = &thread_data[tid];
 153
 154        op = td->opcode;
 155        dat = td->opdata;
 156
 157        switch (op) {
 158        case RTTEST_LOCK:
 159        case RTTEST_LOCKINT:
 160        case RTTEST_LOCKNOWAIT:
 161        case RTTEST_LOCKINTNOWAIT:
 162                if (mutex != &mutexes[dat])
 163                        break;
 164
 165                if (td->mutexes[dat] != 1)
 166                        break;
 167
 168                td->mutexes[dat] = 2;
 169                td->event = atomic_add_return(1, &rttest_event);
 170                break;
 171
 172        default:
 173                break;
 174        }
 175
 176        schedule();
 177
 178
 179        switch (op) {
 180        case RTTEST_LOCK:
 181        case RTTEST_LOCKINT:
 182                if (mutex != &mutexes[dat])
 183                        return;
 184
 185                if (td->mutexes[dat] != 2)
 186                        return;
 187
 188                td->mutexes[dat] = 3;
 189                td->event = atomic_add_return(1, &rttest_event);
 190                break;
 191
 192        case RTTEST_LOCKNOWAIT:
 193        case RTTEST_LOCKINTNOWAIT:
 194                if (mutex != &mutexes[dat])
 195                        return;
 196
 197                if (td->mutexes[dat] != 2)
 198                        return;
 199
 200                td->mutexes[dat] = 1;
 201                td->event = atomic_add_return(1, &rttest_event);
 202                return;
 203
 204        default:
 205                return;
 206        }
 207
 208        td->opcode = 0;
 209
 210        for (;;) {
 211                set_current_state(TASK_INTERRUPTIBLE);
 212
 213                if (td->opcode > 0) {
 214                        int ret;
 215
 216                        set_current_state(TASK_RUNNING);
 217                        ret = handle_op(td, 1);
 218                        set_current_state(TASK_INTERRUPTIBLE);
 219                        if (td->opcode == RTTEST_LOCKCONT)
 220                                break;
 221                        td->opcode = ret;
 222                }
 223
 224                /* Wait for the next command to be executed */
 225                schedule();
 226        }
 227
 228        /* Restore previous command and data */
 229        td->opcode = op;
 230        td->opdata = dat;
 231}
 232
 233static int test_func(void *data)
 234{
 235        struct test_thread_data *td = data;
 236        int ret;
 237
 238        current->flags |= PF_MUTEX_TESTER;
 239        set_freezable();
 240        allow_signal(SIGHUP);
 241
 242        for(;;) {
 243
 244                set_current_state(TASK_INTERRUPTIBLE);
 245
 246                if (td->opcode > 0) {
 247                        set_current_state(TASK_RUNNING);
 248                        ret = handle_op(td, 0);
 249                        set_current_state(TASK_INTERRUPTIBLE);
 250                        td->opcode = ret;
 251                }
 252
 253                /* Wait for the next command to be executed */
 254                schedule();
 255                try_to_freeze();
 256
 257                if (signal_pending(current))
 258                        flush_signals(current);
 259
 260                if(kthread_should_stop())
 261                        break;
 262        }
 263        return 0;
 264}
 265
 266/**
 267 * sysfs_test_command - interface for test commands
 268 * @dev:        thread reference
 269 * @buf:        command for actual step
 270 * @count:      length of buffer
 271 *
 272 * command syntax:
 273 *
 274 * opcode:data
 275 */
 276static ssize_t sysfs_test_command(struct device *dev, struct device_attribute *attr,
 277                                  const char *buf, size_t count)
 278{
 279        struct sched_param schedpar;
 280        struct test_thread_data *td;
 281        char cmdbuf[32];
 282        int op, dat, tid, ret;
 283
 284        td = container_of(dev, struct test_thread_data, dev);
 285        tid = td->dev.id;
 286
 287        /* strings from sysfs write are not 0 terminated! */
 288        if (count >= sizeof(cmdbuf))
 289                return -EINVAL;
 290
 291        /* strip of \n: */
 292        if (buf[count-1] == '\n')
 293                count--;
 294        if (count < 1)
 295                return -EINVAL;
 296
 297        memcpy(cmdbuf, buf, count);
 298        cmdbuf[count] = 0;
 299
 300        if (sscanf(cmdbuf, "%d:%d", &op, &dat) != 2)
 301                return -EINVAL;
 302
 303        switch (op) {
 304        case RTTEST_SCHEDOT:
 305                schedpar.sched_priority = 0;
 306                ret = sched_setscheduler(threads[tid], SCHED_NORMAL, &schedpar);
 307                if (ret)
 308                        return ret;
 309                set_user_nice(current, 0);
 310                break;
 311
 312        case RTTEST_SCHEDRT:
 313                schedpar.sched_priority = dat;
 314                ret = sched_setscheduler(threads[tid], SCHED_FIFO, &schedpar);
 315                if (ret)
 316                        return ret;
 317                break;
 318
 319        case RTTEST_SIGNAL:
 320                send_sig(SIGHUP, threads[tid], 0);
 321                break;
 322
 323        default:
 324                if (td->opcode > 0)
 325                        return -EBUSY;
 326                td->opdata = dat;
 327                td->opcode = op;
 328                wake_up_process(threads[tid]);
 329        }
 330
 331        return count;
 332}
 333
 334/**
 335 * sysfs_test_status - sysfs interface for rt tester
 336 * @dev:        thread to query
 337 * @buf:        char buffer to be filled with thread status info
 338 */
 339static ssize_t sysfs_test_status(struct device *dev, struct device_attribute *attr,
 340                                 char *buf)
 341{
 342        struct test_thread_data *td;
 343        struct task_struct *tsk;
 344        char *curr = buf;
 345        int i;
 346
 347        td = container_of(dev, struct test_thread_data, dev);
 348        tsk = threads[td->dev.id];
 349
 350        spin_lock(&rttest_lock);
 351
 352        curr += sprintf(curr,
 353                "O: %4d, E:%8d, S: 0x%08lx, P: %4d, N: %4d, B: %p, M:",
 354                td->opcode, td->event, tsk->state,
 355                        (MAX_RT_PRIO - 1) - tsk->prio,
 356                        (MAX_RT_PRIO - 1) - tsk->normal_prio,
 357                tsk->pi_blocked_on);
 358
 359        for (i = MAX_RT_TEST_MUTEXES - 1; i >=0 ; i--)
 360                curr += sprintf(curr, "%d", td->mutexes[i]);
 361
 362        spin_unlock(&rttest_lock);
 363
 364        curr += sprintf(curr, ", T: %p, R: %p\n", tsk,
 365                        mutexes[td->dev.id].owner);
 366
 367        return curr - buf;
 368}
 369
 370static DEVICE_ATTR(status, S_IRUSR, sysfs_test_status, NULL);
 371static DEVICE_ATTR(command, S_IWUSR, NULL, sysfs_test_command);
 372
 373static struct bus_type rttest_subsys = {
 374        .name = "rttest",
 375        .dev_name = "rttest",
 376};
 377
 378static int init_test_thread(int id)
 379{
 380        thread_data[id].dev.bus = &rttest_subsys;
 381        thread_data[id].dev.id = id;
 382
 383        threads[id] = kthread_run(test_func, &thread_data[id], "rt-test-%d", id);
 384        if (IS_ERR(threads[id]))
 385                return PTR_ERR(threads[id]);
 386
 387        return device_register(&thread_data[id].dev);
 388}
 389
 390static int init_rttest(void)
 391{
 392        int ret, i;
 393
 394        spin_lock_init(&rttest_lock);
 395
 396        for (i = 0; i < MAX_RT_TEST_MUTEXES; i++)
 397                rt_mutex_init(&mutexes[i]);
 398
 399        ret = subsys_system_register(&rttest_subsys, NULL);
 400        if (ret)
 401                return ret;
 402
 403        for (i = 0; i < MAX_RT_TEST_THREADS; i++) {
 404                ret = init_test_thread(i);
 405                if (ret)
 406                        break;
 407                ret = device_create_file(&thread_data[i].dev, &dev_attr_status);
 408                if (ret)
 409                        break;
 410                ret = device_create_file(&thread_data[i].dev, &dev_attr_command);
 411                if (ret)
 412                        break;
 413        }
 414
 415        printk("Initializing RT-Tester: %s\n", ret ? "Failed" : "OK" );
 416
 417        return ret;
 418}
 419
 420device_initcall(init_rttest);
 421
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