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
  18#include "rtmutex.h"
  19
  20#define MAX_RT_TEST_THREADS     8
  21#define MAX_RT_TEST_MUTEXES     8
  22
  23static spinlock_t rttest_lock;
  24static atomic_t rttest_event;
  25
  26struct test_thread_data {
  27        int                     opcode;
  28        int                     opdata;
  29        int                     mutexes[MAX_RT_TEST_MUTEXES];
  30        int                     event;
  31        struct device           dev;
  32};
  33
  34static struct test_thread_data thread_data[MAX_RT_TEST_THREADS];
  35static struct task_struct *threads[MAX_RT_TEST_THREADS];
  36static struct rt_mutex mutexes[MAX_RT_TEST_MUTEXES];
  37
  38enum test_opcodes {
  39        RTTEST_NOP = 0,
  40        RTTEST_SCHEDOT,         /* 1 Sched other, data = nice */
  41        RTTEST_SCHEDRT,         /* 2 Sched fifo, data = prio */
  42        RTTEST_LOCK,            /* 3 Lock uninterruptible, data = lockindex */
  43        RTTEST_LOCKNOWAIT,      /* 4 Lock uninterruptible no wait in wakeup, data = lockindex */
  44        RTTEST_LOCKINT,         /* 5 Lock interruptible, data = lockindex */
  45        RTTEST_LOCKINTNOWAIT,   /* 6 Lock interruptible no wait in wakeup, data = lockindex */
  46        RTTEST_LOCKCONT,        /* 7 Continue locking after the wakeup delay */
  47        RTTEST_UNLOCK,          /* 8 Unlock, data = lockindex */
  48        /* 9, 10 - reserved for BKL commemoration */
  49        RTTEST_SIGNAL = 11,     /* 11 Signal other test thread, data = thread id */
  50        RTTEST_RESETEVENT = 98, /* 98 Reset event counter */
  51        RTTEST_RESET = 99,      /* 99 Reset all pending operations */
  52};
  53
  54static int handle_op(struct test_thread_data *td, int lockwakeup)
  55{
  56        int i, id, ret = -EINVAL;
  57
  58        switch(td->opcode) {
  59
  60        case RTTEST_NOP:
  61                return 0;
  62
  63        case RTTEST_LOCKCONT:
  64                td->mutexes[td->opdata] = 1;
  65                td->event = atomic_add_return(1, &rttest_event);
  66                return 0;
  67
  68        case RTTEST_RESET:
  69                for (i = 0; i < MAX_RT_TEST_MUTEXES; i++) {
  70                        if (td->mutexes[i] == 4) {
  71                                rt_mutex_unlock(&mutexes[i]);
  72                                td->mutexes[i] = 0;
  73                        }
  74                }
  75                return 0;
  76
  77        case RTTEST_RESETEVENT:
  78                atomic_set(&rttest_event, 0);
  79                return 0;
  80
  81        default:
  82                if (lockwakeup)
  83                        return ret;
  84        }
  85
  86        switch(td->opcode) {
  87
  88        case RTTEST_LOCK:
  89        case RTTEST_LOCKNOWAIT:
  90                id = td->opdata;
  91                if (id < 0 || id >= MAX_RT_TEST_MUTEXES)
  92                        return ret;
  93
  94                td->mutexes[id] = 1;
  95                td->event = atomic_add_return(1, &rttest_event);
  96                rt_mutex_lock(&mutexes[id]);
  97                td->event = atomic_add_return(1, &rttest_event);
  98                td->mutexes[id] = 4;
  99                return 0;
 100
 101        case RTTEST_LOCKINT:
 102        case RTTEST_LOCKINTNOWAIT:
 103                id = td->opdata;
 104                if (id < 0 || id >= MAX_RT_TEST_MUTEXES)
 105                        return ret;
 106
 107                td->mutexes[id] = 1;
 108                td->event = atomic_add_return(1, &rttest_event);
 109                ret = rt_mutex_lock_interruptible(&mutexes[id], 0);
 110                td->event = atomic_add_return(1, &rttest_event);
 111                td->mutexes[id] = ret ? 0 : 4;
 112                return ret ? -EINTR : 0;
 113
 114        case RTTEST_UNLOCK:
 115                id = td->opdata;
 116                if (id < 0 || id >= MAX_RT_TEST_MUTEXES || td->mutexes[id] != 4)
 117                        return ret;
 118
 119                td->event = atomic_add_return(1, &rttest_event);
 120                rt_mutex_unlock(&mutexes[id]);
 121                td->event = atomic_add_return(1, &rttest_event);
 122                td->mutexes[id] = 0;
 123                return 0;
 124
 125        default:
 126                break;
 127        }
 128        return ret;
 129}
 130
 131/*
 132 * Schedule replacement for rtsem_down(). Only called for threads with
 133 * PF_MUTEX_TESTER set.
 134 *
 135 * This allows us to have finegrained control over the event flow.
 136 *
 137 */
 138void schedule_rt_mutex_test(struct rt_mutex *mutex)
 139{
 140        int tid, op, dat;
 141        struct test_thread_data *td;
 142
 143        /* We have to lookup the task */
 144        for (tid = 0; tid < MAX_RT_TEST_THREADS; tid++) {
 145                if (threads[tid] == current)
 146                        break;
 147        }
 148
 149        BUG_ON(tid == MAX_RT_TEST_THREADS);
 150
 151        td = &thread_data[tid];
 152
 153        op = td->opcode;
 154        dat = td->opdata;
 155
 156        switch (op) {
 157        case RTTEST_LOCK:
 158        case RTTEST_LOCKINT:
 159        case RTTEST_LOCKNOWAIT:
 160        case RTTEST_LOCKINTNOWAIT:
 161                if (mutex != &mutexes[dat])
 162                        break;
 163
 164                if (td->mutexes[dat] != 1)
 165                        break;
 166
 167                td->mutexes[dat] = 2;
 168                td->event = atomic_add_return(1, &rttest_event);
 169                break;
 170
 171        default:
 172                break;
 173        }
 174
 175        schedule();
 176
 177
 178        switch (op) {
 179        case RTTEST_LOCK:
 180        case RTTEST_LOCKINT:
 181                if (mutex != &mutexes[dat])
 182                        return;
 183
 184                if (td->mutexes[dat] != 2)
 185                        return;
 186
 187                td->mutexes[dat] = 3;
 188                td->event = atomic_add_return(1, &rttest_event);
 189                break;
 190
 191        case RTTEST_LOCKNOWAIT:
 192        case RTTEST_LOCKINTNOWAIT:
 193                if (mutex != &mutexes[dat])
 194                        return;
 195
 196                if (td->mutexes[dat] != 2)
 197                        return;
 198
 199                td->mutexes[dat] = 1;
 200                td->event = atomic_add_return(1, &rttest_event);
 201                return;
 202
 203        default:
 204                return;
 205        }
 206
 207        td->opcode = 0;
 208
 209        for (;;) {
 210                set_current_state(TASK_INTERRUPTIBLE);
 211
 212                if (td->opcode > 0) {
 213                        int ret;
 214
 215                        set_current_state(TASK_RUNNING);
 216                        ret = handle_op(td, 1);
 217                        set_current_state(TASK_INTERRUPTIBLE);
 218                        if (td->opcode == RTTEST_LOCKCONT)
 219                                break;
 220                        td->opcode = ret;
 221                }
 222
 223                /* Wait for the next command to be executed */
 224                schedule();
 225        }
 226
 227        /* Restore previous command and data */
 228        td->opcode = op;
 229        td->opdata = dat;
 230}
 231
 232static int test_func(void *data)
 233{
 234        struct test_thread_data *td = data;
 235        int ret;
 236
 237        current->flags |= PF_MUTEX_TESTER;
 238        set_freezable();
 239        allow_signal(SIGHUP);
 240
 241        for(;;) {
 242
 243                set_current_state(TASK_INTERRUPTIBLE);
 244
 245                if (td->opcode > 0) {
 246                        set_current_state(TASK_RUNNING);
 247                        ret = handle_op(td, 0);
 248                        set_current_state(TASK_INTERRUPTIBLE);
 249                        td->opcode = ret;
 250                }
 251
 252                /* Wait for the next command to be executed */
 253                schedule();
 254                try_to_freeze();
 255
 256                if (signal_pending(current))
 257                        flush_signals(current);
 258
 259                if(kthread_should_stop())
 260                        break;
 261        }
 262        return 0;
 263}
 264
 265/**
 266 * sysfs_test_command - interface for test commands
 267 * @dev:        thread reference
 268 * @buf:        command for actual step
 269 * @count:      length of buffer
 270 *
 271 * command syntax:
 272 *
 273 * opcode:data
 274 */
 275static ssize_t sysfs_test_command(struct device *dev, struct device_attribute *attr,
 276                                  const char *buf, size_t count)
 277{
 278        struct sched_param schedpar;
 279        struct test_thread_data *td;
 280        char cmdbuf[32];
 281        int op, dat, tid, ret;
 282
 283        td = container_of(dev, struct test_thread_data, dev);
 284        tid = td->dev.id;
 285
 286        /* strings from sysfs write are not 0 terminated! */
 287        if (count >= sizeof(cmdbuf))
 288                return -EINVAL;
 289
 290        /* strip of \n: */
 291        if (buf[count-1] == '\n')
 292                count--;
 293        if (count < 1)
 294                return -EINVAL;
 295
 296        memcpy(cmdbuf, buf, count);
 297        cmdbuf[count] = 0;
 298
 299        if (sscanf(cmdbuf, "%d:%d", &op, &dat) != 2)
 300                return -EINVAL;
 301
 302        switch (op) {
 303        case RTTEST_SCHEDOT:
 304                schedpar.sched_priority = 0;
 305                ret = sched_setscheduler(threads[tid], SCHED_NORMAL, &schedpar);
 306                if (ret)
 307                        return ret;
 308                set_user_nice(current, 0);
 309                break;
 310
 311        case RTTEST_SCHEDRT:
 312                schedpar.sched_priority = dat;
 313                ret = sched_setscheduler(threads[tid], SCHED_FIFO, &schedpar);
 314                if (ret)
 315                        return ret;
 316                break;
 317
 318        case RTTEST_SIGNAL:
 319                send_sig(SIGHUP, threads[tid], 0);
 320                break;
 321
 322        default:
 323                if (td->opcode > 0)
 324                        return -EBUSY;
 325                td->opdata = dat;
 326                td->opcode = op;
 327                wake_up_process(threads[tid]);
 328        }
 329
 330        return count;
 331}
 332
 333/**
 334 * sysfs_test_status - sysfs interface for rt tester
 335 * @dev:        thread to query
 336 * @buf:        char buffer to be filled with thread status info
 337 */
 338static ssize_t sysfs_test_status(struct device *dev, struct device_attribute *attr,
 339                                 char *buf)
 340{
 341        struct test_thread_data *td;
 342        struct task_struct *tsk;
 343        char *curr = buf;
 344        int i;
 345
 346        td = container_of(dev, struct test_thread_data, dev);
 347        tsk = threads[td->dev.id];
 348
 349        spin_lock(&rttest_lock);
 350
 351        curr += sprintf(curr,
 352                "O: %4d, E:%8d, S: 0x%08lx, P: %4d, N: %4d, B: %p, M:",
 353                td->opcode, td->event, tsk->state,
 354                        (MAX_RT_PRIO - 1) - tsk->prio,
 355                        (MAX_RT_PRIO - 1) - tsk->normal_prio,
 356                tsk->pi_blocked_on);
 357
 358        for (i = MAX_RT_TEST_MUTEXES - 1; i >=0 ; i--)
 359                curr += sprintf(curr, "%d", td->mutexes[i]);
 360
 361        spin_unlock(&rttest_lock);
 362
 363        curr += sprintf(curr, ", T: %p, R: %p\n", tsk,
 364                        mutexes[td->dev.id].owner);
 365
 366        return curr - buf;
 367}
 368
 369static DEVICE_ATTR(status, 0600, sysfs_test_status, NULL);
 370static DEVICE_ATTR(command, 0600, NULL, sysfs_test_command);
 371
 372static struct bus_type rttest_subsys = {
 373        .name = "rttest",
 374        .dev_name = "rttest",
 375};
 376
 377static int init_test_thread(int id)
 378{
 379        thread_data[id].dev.bus = &rttest_subsys;
 380        thread_data[id].dev.id = id;
 381
 382        threads[id] = kthread_run(test_func, &thread_data[id], "rt-test-%d", id);
 383        if (IS_ERR(threads[id]))
 384                return PTR_ERR(threads[id]);
 385
 386        return device_register(&thread_data[id].dev);
 387}
 388
 389static int init_rttest(void)
 390{
 391        int ret, i;
 392
 393        spin_lock_init(&rttest_lock);
 394
 395        for (i = 0; i < MAX_RT_TEST_MUTEXES; i++)
 396                rt_mutex_init(&mutexes[i]);
 397
 398        ret = subsys_system_register(&rttest_subsys, NULL);
 399        if (ret)
 400                return ret;
 401
 402        for (i = 0; i < MAX_RT_TEST_THREADS; i++) {
 403                ret = init_test_thread(i);
 404                if (ret)
 405                        break;
 406                ret = device_create_file(&thread_data[i].dev, &dev_attr_status);
 407                if (ret)
 408                        break;
 409                ret = device_create_file(&thread_data[i].dev, &dev_attr_command);
 410                if (ret)
 411                        break;
 412        }
 413
 414        printk("Initializing RT-Tester: %s\n", ret ? "Failed" : "OK" );
 415
 416        return ret;
 417}
 418
 419device_initcall(init_rttest);
 420
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