LXR linux/kernel/rtmutex-tester.c

   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/kthread.h>
  10#include <linux/module.h>
  11#include <linux/sched.h>
  12#include <linux/smp_lock.h>
  13#include <linux/spinlock.h>
  14#include <linux/sysdev.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                     bkl;
  31        int                     event;
  32        struct sys_device       sysdev;
  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        RTTEST_LOCKBKL,         /* 9 Lock BKL */
  50        RTTEST_UNLOCKBKL,       /* 10 Unlock BKL */
  51        RTTEST_SIGNAL,          /* 11 Signal other test thread, data = thread id */
  52        RTTEST_RESETEVENT = 98, /* 98 Reset event counter */
  53        RTTEST_RESET = 99,      /* 99 Reset all pending operations */
  54};
  55
  56static int handle_op(struct test_thread_data *td, int lockwakeup)
  57{
  58        int i, id, ret = -EINVAL;
  59
  60        switch(td->opcode) {
  61
  62        case RTTEST_NOP:
  63                return 0;
  64
  65        case RTTEST_LOCKCONT:
  66                td->mutexes[td->opdata] = 1;
  67                td->event = atomic_add_return(1, &rttest_event);
  68                return 0;
  69
  70        case RTTEST_RESET:
  71                for (i = 0; i < MAX_RT_TEST_MUTEXES; i++) {
  72                        if (td->mutexes[i] == 4) {
  73                                rt_mutex_unlock(&mutexes[i]);
  74                                td->mutexes[i] = 0;
  75                        }
  76                }
  77
  78                if (!lockwakeup && td->bkl == 4) {
  79                        unlock_kernel();
  80                        td->bkl = 0;
  81                }
  82                return 0;
  83
  84        case RTTEST_RESETEVENT:
  85                atomic_set(&rttest_event, 0);
  86                return 0;
  87
  88        default:
  89                if (lockwakeup)
  90                        return ret;
  91        }
  92
  93        switch(td->opcode) {
  94
  95        case RTTEST_LOCK:
  96        case RTTEST_LOCKNOWAIT:
  97                id = td->opdata;
  98                if (id < 0 || id >= MAX_RT_TEST_MUTEXES)
  99                        return ret;
 100
 101                td->mutexes[id] = 1;
 102                td->event = atomic_add_return(1, &rttest_event);
 103                rt_mutex_lock(&mutexes[id]);
 104                td->event = atomic_add_return(1, &rttest_event);
 105                td->mutexes[id] = 4;
 106                return 0;
 107
 108        case RTTEST_LOCKINT:
 109        case RTTEST_LOCKINTNOWAIT:
 110                id = td->opdata;
 111                if (id < 0 || id >= MAX_RT_TEST_MUTEXES)
 112                        return ret;
 113
 114                td->mutexes[id] = 1;
 115                td->event = atomic_add_return(1, &rttest_event);
 116                ret = rt_mutex_lock_interruptible(&mutexes[id], 0);
 117                td->event = atomic_add_return(1, &rttest_event);
 118                td->mutexes[id] = ret ? 0 : 4;
 119                return ret ? -EINTR : 0;
 120
 121        case RTTEST_UNLOCK:
 122                id = td->opdata;
 123                if (id < 0 || id >= MAX_RT_TEST_MUTEXES || td->mutexes[id] != 4)
 124                        return ret;
 125
 126                td->event = atomic_add_return(1, &rttest_event);
 127                rt_mutex_unlock(&mutexes[id]);
 128                td->event = atomic_add_return(1, &rttest_event);
 129                td->mutexes[id] = 0;
 130                return 0;
 131
 132        case RTTEST_LOCKBKL:
 133                if (td->bkl)
 134                        return 0;
 135                td->bkl = 1;
 136                lock_kernel();
 137                td->bkl = 4;
 138                return 0;
 139
 140        case RTTEST_UNLOCKBKL:
 141                if (td->bkl != 4)
 142                        break;
 143                unlock_kernel();
 144                td->bkl = 0;
 145                return 0;
 146
 147        default:
 148                break;
 149        }
 150        return ret;
 151}
 152
 153/*
 154 * Schedule replacement for rtsem_down(). Only called for threads with
 155 * PF_MUTEX_TESTER set.
 156 *
 157 * This allows us to have finegrained control over the event flow.
 158 *
 159 */
 160void schedule_rt_mutex_test(struct rt_mutex *mutex)
 161{
 162        int tid, op, dat;
 163        struct test_thread_data *td;
 164
 165        /* We have to lookup the task */
 166        for (tid = 0; tid < MAX_RT_TEST_THREADS; tid++) {
 167                if (threads[tid] == current)
 168                        break;
 169        }
 170
 171        BUG_ON(tid == MAX_RT_TEST_THREADS);
 172
 173        td = &thread_data[tid];
 174
 175        op = td->opcode;
 176        dat = td->opdata;
 177
 178        switch (op) {
 179        case RTTEST_LOCK:
 180        case RTTEST_LOCKINT:
 181        case RTTEST_LOCKNOWAIT:
 182        case RTTEST_LOCKINTNOWAIT:
 183                if (mutex != &mutexes[dat])
 184                        break;
 185
 186                if (td->mutexes[dat] != 1)
 187                        break;
 188
 189                td->mutexes[dat] = 2;
 190                td->event = atomic_add_return(1, &rttest_event);
 191                break;
 192
 193        case RTTEST_LOCKBKL:
 194        default:
 195                break;
 196        }
 197
 198        schedule();
 199
 200
 201        switch (op) {
 202        case RTTEST_LOCK:
 203        case RTTEST_LOCKINT:
 204                if (mutex != &mutexes[dat])
 205                        return;
 206
 207                if (td->mutexes[dat] != 2)
 208                        return;
 209
 210                td->mutexes[dat] = 3;
 211                td->event = atomic_add_return(1, &rttest_event);
 212                break;
 213
 214        case RTTEST_LOCKNOWAIT:
 215        case RTTEST_LOCKINTNOWAIT:
 216                if (mutex != &mutexes[dat])
 217                        return;
 218
 219                if (td->mutexes[dat] != 2)
 220                        return;
 221
 222                td->mutexes[dat] = 1;
 223                td->event = atomic_add_return(1, &rttest_event);
 224                return;
 225
 226        case RTTEST_LOCKBKL:
 227                return;
 228        default:
 229                return;
 230        }
 231
 232        td->opcode = 0;
 233
 234        for (;;) {
 235                set_current_state(TASK_INTERRUPTIBLE);
 236
 237                if (td->opcode > 0) {
 238                        int ret;
 239
 240                        set_current_state(TASK_RUNNING);
 241                        ret = handle_op(td, 1);
 242                        set_current_state(TASK_INTERRUPTIBLE);
 243                        if (td->opcode == RTTEST_LOCKCONT)
 244                                break;
 245                        td->opcode = ret;
 246                }
 247
 248                /* Wait for the next command to be executed */
 249                schedule();
 250        }
 251
 252        /* Restore previous command and data */
 253        td->opcode = op;
 254        td->opdata = dat;
 255}
 256
 257static int test_func(void *data)
 258{
 259        struct test_thread_data *td = data;
 260        int ret;
 261
 262        current->flags |= PF_MUTEX_TESTER;
 263        set_freezable();
 264        allow_signal(SIGHUP);
 265
 266        for(;;) {
 267
 268                set_current_state(TASK_INTERRUPTIBLE);
 269
 270                if (td->opcode > 0) {
 271                        set_current_state(TASK_RUNNING);
 272                        ret = handle_op(td, 0);
 273                        set_current_state(TASK_INTERRUPTIBLE);
 274                        td->opcode = ret;
 275                }
 276
 277                /* Wait for the next command to be executed */
 278                schedule();
 279                try_to_freeze();
 280
 281                if (signal_pending(current))
 282                        flush_signals(current);
 283
 284                if(kthread_should_stop())
 285                        break;
 286        }
 287        return 0;
 288}
 289
 290/**
 291 * sysfs_test_command - interface for test commands
 292 * @dev:        thread reference
 293 * @buf:        command for actual step
 294 * @count:      length of buffer
 295 *
 296 * command syntax:
 297 *
 298 * opcode:data
 299 */
 300static ssize_t sysfs_test_command(struct sys_device *dev, struct sysdev_attribute *attr,
 301                                  const char *buf, size_t count)
 302{
 303        struct sched_param schedpar;
 304        struct test_thread_data *td;
 305        char cmdbuf[32];
 306        int op, dat, tid, ret;
 307
 308        td = container_of(dev, struct test_thread_data, sysdev);
 309        tid = td->sysdev.id;
 310
 311        /* strings from sysfs write are not 0 terminated! */
 312        if (count >= sizeof(cmdbuf))
 313                return -EINVAL;
 314
 315        /* strip of \n: */
 316        if (buf[count-1] == '\n')
 317                count--;
 318        if (count < 1)
 319                return -EINVAL;
 320
 321        memcpy(cmdbuf, buf, count);
 322        cmdbuf[count] = 0;
 323
 324        if (sscanf(cmdbuf, "%d:%d", &op, &dat) != 2)
 325                return -EINVAL;
 326
 327        switch (op) {
 328        case RTTEST_SCHEDOT:
 329                schedpar.sched_priority = 0;
 330                ret = sched_setscheduler(threads[tid], SCHED_NORMAL, &schedpar);
 331                if (ret)
 332                        return ret;
 333                set_user_nice(current, 0);
 334                break;
 335
 336        case RTTEST_SCHEDRT:
 337                schedpar.sched_priority = dat;
 338                ret = sched_setscheduler(threads[tid], SCHED_FIFO, &schedpar);
 339                if (ret)
 340                        return ret;
 341                break;
 342
 343        case RTTEST_SIGNAL:
 344                send_sig(SIGHUP, threads[tid], 0);
 345                break;
 346
 347        default:
 348                if (td->opcode > 0)
 349                        return -EBUSY;
 350                td->opdata = dat;
 351                td->opcode = op;
 352                wake_up_process(threads[tid]);
 353        }
 354
 355        return count;
 356}
 357
 358/**
 359 * sysfs_test_status - sysfs interface for rt tester
 360 * @dev:        thread to query
 361 * @buf:        char buffer to be filled with thread status info
 362 */
 363static ssize_t sysfs_test_status(struct sys_device *dev, struct sysdev_attribute *attr,
 364                                 char *buf)
 365{
 366        struct test_thread_data *td;
 367        struct task_struct *tsk;
 368        char *curr = buf;
 369        int i;
 370
 371        td = container_of(dev, struct test_thread_data, sysdev);
 372        tsk = threads[td->sysdev.id];
 373
 374        spin_lock(&rttest_lock);
 375
 376        curr += sprintf(curr,
 377                "O: %4d, E:%8d, S: 0x%08lx, P: %4d, N: %4d, B: %p, K: %d, M:",
 378                td->opcode, td->event, tsk->state,
 379                        (MAX_RT_PRIO - 1) - tsk->prio,
 380                        (MAX_RT_PRIO - 1) - tsk->normal_prio,
 381                tsk->pi_blocked_on, td->bkl);
 382
 383        for (i = MAX_RT_TEST_MUTEXES - 1; i >=0 ; i--)
 384                curr += sprintf(curr, "%d", td->mutexes[i]);
 385
 386        spin_unlock(&rttest_lock);
 387
 388        curr += sprintf(curr, ", T: %p, R: %p\n", tsk,
 389                        mutexes[td->sysdev.id].owner);
 390
 391        return curr - buf;
 392}
 393
 394static SYSDEV_ATTR(status, 0600, sysfs_test_status, NULL);
 395static SYSDEV_ATTR(command, 0600, NULL, sysfs_test_command);
 396
 397static struct sysdev_class rttest_sysclass = {
 398        .name = "rttest",
 399};
 400
 401static int init_test_thread(int id)
 402{
 403        thread_data[id].sysdev.cls = &rttest_sysclass;
 404        thread_data[id].sysdev.id = id;
 405
 406        threads[id] = kthread_run(test_func, &thread_data[id], "rt-test-%d", id);
 407        if (IS_ERR(threads[id]))
 408                return PTR_ERR(threads[id]);
 409
 410        return sysdev_register(&thread_data[id].sysdev);
 411}
 412
 413static int init_rttest(void)
 414{
 415        int ret, i;
 416
 417        spin_lock_init(&rttest_lock);
 418
 419        for (i = 0; i < MAX_RT_TEST_MUTEXES; i++)
 420                rt_mutex_init(&mutexes[i]);
 421
 422        ret = sysdev_class_register(&rttest_sysclass);
 423        if (ret)
 424                return ret;
 425
 426        for (i = 0; i < MAX_RT_TEST_THREADS; i++) {
 427                ret = init_test_thread(i);
 428                if (ret)
 429                        break;
 430                ret = sysdev_create_file(&thread_data[i].sysdev, &attr_status);
 431                if (ret)
 432                        break;
 433                ret = sysdev_create_file(&thread_data[i].sysdev, &attr_command);
 434                if (ret)
 435                        break;
 436        }
 437
 438        printk("Initializing RT-Tester: %s\n", ret ? "Failed" : "OK" );
 439
 440        return ret;
 441}
 442
 443device_initcall(init_rttest);
 444