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/spinlock.h>
  14#include <linux/timer.h>
  15#include <linux/freezer.h>
  16
  17#include "rtmutex.h"
  18
  19#define MAX_RT_TEST_THREADS     8
  20#define MAX_RT_TEST_MUTEXES     8
  21
  22static spinlock_t rttest_lock;
  23static atomic_t rttest_event;
  24
  25struct test_thread_data {
  26        int                     opcode;
  27        int                     opdata;
  28        int                     mutexes[MAX_RT_TEST_MUTEXES];
  29        int                     event;
  30        struct device           dev;
  31};
  32
  33static struct test_thread_data thread_data[MAX_RT_TEST_THREADS];
  34static struct task_struct *threads[MAX_RT_TEST_THREADS];
  35static struct rt_mutex mutexes[MAX_RT_TEST_MUTEXES];
  36
  37enum test_opcodes {
  38        RTTEST_NOP = 0,
  39        RTTEST_SCHEDOT,         /* 1 Sched other, data = nice */
  40        RTTEST_SCHEDRT,         /* 2 Sched fifo, data = prio */
  41        RTTEST_LOCK,            /* 3 Lock uninterruptible, data = lockindex */
  42        RTTEST_LOCKNOWAIT,      /* 4 Lock uninterruptible no wait in wakeup, data = lockindex */
  43        RTTEST_LOCKINT,         /* 5 Lock interruptible, data = lockindex */
  44        RTTEST_LOCKINTNOWAIT,   /* 6 Lock interruptible no wait in wakeup, data = lockindex */
  45        RTTEST_LOCKCONT,        /* 7 Continue locking after the wakeup delay */
  46        RTTEST_UNLOCK,          /* 8 Unlock, data = lockindex */
  47        /* 9, 10 - reserved for BKL commemoration */
  48        RTTEST_SIGNAL = 11,     /* 11 Signal other test thread, data = thread id */
  49        RTTEST_RESETEVENT = 98, /* 98 Reset event counter */
  50        RTTEST_RESET = 99,      /* 99 Reset all pending operations */
  51};
  52
  53static int handle_op(struct test_thread_data *td, int lockwakeup)
  54{
  55        int i, id, ret = -EINVAL;
  56
  57        switch(td->opcode) {
  58
  59        case RTTEST_NOP:
  60                return 0;
  61
  62        case RTTEST_LOCKCONT:
  63                td->mutexes[td->opdata] = 1;
  64                td->event = atomic_add_return(1, &rttest_event);
  65                return 0;
  66
  67        case RTTEST_RESET:
  68                for (i = 0; i < MAX_RT_TEST_MUTEXES; i++) {
  69                        if (td->mutexes[i] == 4) {
  70                                rt_mutex_unlock(&mutexes[i]);
  71                                td->mutexes[i] = 0;
  72                        }
  73                }
  74                return 0;
  75
  76        case RTTEST_RESETEVENT:
  77                atomic_set(&rttest_event, 0);
  78                return 0;
  79
  80        default:
  81                if (lockwakeup)
  82                        return ret;
  83        }
  84
  85        switch(td->opcode) {
  86
  87        case RTTEST_LOCK:
  88        case RTTEST_LOCKNOWAIT:
  89                id = td->opdata;
  90                if (id < 0 || id >= MAX_RT_TEST_MUTEXES)
  91                        return ret;
  92
  93                td->mutexes[id] = 1;
  94                td->event = atomic_add_return(1, &rttest_event);
  95                rt_mutex_lock(&mutexes[id]);
  96                td->event = atomic_add_return(1, &rttest_event);
  97                td->mutexes[id] = 4;
  98                return 0;
  99
 100        case RTTEST_LOCKINT:
 101        case RTTEST_LOCKINTNOWAIT:
 102                id = td->opdata;
 103                if (id < 0 || id >= MAX_RT_TEST_MUTEXES)
 104                        return ret;
 105
 106                td->mutexes[id] = 1;
 107                td->event = atomic_add_return(1, &rttest_event);
 108                ret = rt_mutex_lock_interruptible(&mutexes[id], 0);
 109                td->event = atomic_add_return(1, &rttest_event);
 110                td->mutexes[id] = ret ? 0 : 4;
 111                return ret ? -EINTR : 0;
 112
 113        case RTTEST_UNLOCK:
 114                id = td->opdata;
 115                if (id < 0 || id >= MAX_RT_TEST_MUTEXES || td->mutexes[id] != 4)
 116                        return ret;
 117
 118                td->event = atomic_add_return(1, &rttest_event);
 119                rt_mutex_unlock(&mutexes[id]);
 120                td->event = atomic_add_return(1, &rttest_event);
 121                td->mutexes[id] = 0;
 122                return 0;
 123
 124        default:
 125                break;
 126        }
 127        return ret;
 128}
 129
 130/*
 131 * Schedule replacement for rtsem_down(). Only called for threads with
 132 * PF_MUTEX_TESTER set.
 133 *
 134 * This allows us to have finegrained control over the event flow.
 135 *
 136 */
 137void schedule_rt_mutex_test(struct rt_mutex *mutex)
 138{
 139        int tid, op, dat;
 140        struct test_thread_data *td;
 141
 142        /* We have to lookup the task */
 143        for (tid = 0; tid < MAX_RT_TEST_THREADS; tid++) {
 144                if (threads[tid] == current)
 145                        break;
 146        }
 147
 148        BUG_ON(tid == MAX_RT_TEST_THREADS);
 149
 150        td = &thread_data[tid];
 151
 152        op = td->opcode;
 153        dat = td->opdata;
 154
 155        switch (op) {
 156        case RTTEST_LOCK:
 157        case RTTEST_LOCKINT:
 158        case RTTEST_LOCKNOWAIT:
 159        case RTTEST_LOCKINTNOWAIT:
 160                if (mutex != &mutexes[dat])
 161                        break;
 162
 163                if (td->mutexes[dat] != 1)
 164                        break;
 165
 166                td->mutexes[dat] = 2;
 167                td->event = atomic_add_return(1, &rttest_event);
 168                break;
 169
 170        default:
 171                break;
 172        }
 173
 174        schedule();
 175
 176
 177        switch (op) {
 178        case RTTEST_LOCK:
 179        case RTTEST_LOCKINT:
 180                if (mutex != &mutexes[dat])
 181                        return;
 182
 183                if (td->mutexes[dat] != 2)
 184                        return;
 185
 186                td->mutexes[dat] = 3;
 187                td->event = atomic_add_return(1, &rttest_event);
 188                break;
 189
 190        case RTTEST_LOCKNOWAIT:
 191        case RTTEST_LOCKINTNOWAIT:
 192                if (mutex != &mutexes[dat])
 193                        return;
 194
 195                if (td->mutexes[dat] != 2)
 196                        return;
 197
 198                td->mutexes[dat] = 1;
 199                td->event = atomic_add_return(1, &rttest_event);
 200                return;
 201
 202        default:
 203                return;
 204        }
 205
 206        td->opcode = 0;
 207
 208        for (;;) {
 209                set_current_state(TASK_INTERRUPTIBLE);
 210
 211                if (td->opcode > 0) {
 212                        int ret;
 213
 214                        set_current_state(TASK_RUNNING);
 215                        ret = handle_op(td, 1);
 216                        set_current_state(TASK_INTERRUPTIBLE);
 217                        if (td->opcode == RTTEST_LOCKCONT)
 218                                break;
 219                        td->opcode = ret;
 220                }
 221
 222                /* Wait for the next command to be executed */
 223                schedule();
 224        }
 225
 226        /* Restore previous command and data */
 227        td->opcode = op;
 228        td->opdata = dat;
 229}
 230
 231static int test_func(void *data)
 232{
 233        struct test_thread_data *td = data;
 234        int ret;
 235
 236        current->flags |= PF_MUTEX_TESTER;
 237        set_freezable();
 238        allow_signal(SIGHUP);
 239
 240        for(;;) {
 241
 242                set_current_state(TASK_INTERRUPTIBLE);
 243
 244                if (td->opcode > 0) {
 245                        set_current_state(TASK_RUNNING);
 246                        ret = handle_op(td, 0);
 247                        set_current_state(TASK_INTERRUPTIBLE);
 248                        td->opcode = ret;
 249                }
 250
 251                /* Wait for the next command to be executed */
 252                schedule();
 253                try_to_freeze();
 254
 255                if (signal_pending(current))
 256                        flush_signals(current);
 257
 258                if(kthread_should_stop())
 259                        break;
 260        }
 261        return 0;
 262}
 263
 264/**
 265 * sysfs_test_command - interface for test commands
 266 * @dev:        thread reference
 267 * @buf:        command for actual step
 268 * @count:      length of buffer
 269 *
 270 * command syntax:
 271 *
 272 * opcode:data
 273 */
 274static ssize_t sysfs_test_command(struct device *dev, struct device_attribute *attr,
 275                                  const char *buf, size_t count)
 276{
 277        struct sched_param schedpar;
 278        struct test_thread_data *td;
 279        char cmdbuf[32];
 280        int op, dat, tid, ret;
 281
 282        td = container_of(dev, struct test_thread_data, dev);
 283        tid = td->dev.id;
 284
 285        /* strings from sysfs write are not 0 terminated! */
 286        if (count >= sizeof(cmdbuf))
 287                return -EINVAL;
 288
 289        /* strip of \n: */
 290        if (buf[count-1] == '\n')
 291                count--;
 292        if (count < 1)
 293                return -EINVAL;
 294
 295        memcpy(cmdbuf, buf, count);
 296        cmdbuf[count] = 0;
 297
 298        if (sscanf(cmdbuf, "%d:%d", &op, &dat) != 2)
 299                return -EINVAL;
 300
 301        switch (op) {
 302        case RTTEST_SCHEDOT:
 303                schedpar.sched_priority = 0;
 304                ret = sched_setscheduler(threads[tid], SCHED_NORMAL, &schedpar);
 305                if (ret)
 306                        return ret;
 307                set_user_nice(current, 0);
 308                break;
 309
 310        case RTTEST_SCHEDRT:
 311                schedpar.sched_priority = dat;
 312                ret = sched_setscheduler(threads[tid], SCHED_FIFO, &schedpar);
 313                if (ret)
 314                        return ret;
 315                break;
 316
 317        case RTTEST_SIGNAL:
 318                send_sig(SIGHUP, threads[tid], 0);
 319                break;
 320
 321        default:
 322                if (td->opcode > 0)
 323                        return -EBUSY;
 324                td->opdata = dat;
 325                td->opcode = op;
 326                wake_up_process(threads[tid]);
 327        }
 328
 329        return count;
 330}
 331
 332/**
 333 * sysfs_test_status - sysfs interface for rt tester
 334 * @dev:        thread to query
 335 * @buf:        char buffer to be filled with thread status info
 336 */
 337static ssize_t sysfs_test_status(struct device *dev, struct device_attribute *attr,
 338                                 char *buf)
 339{
 340        struct test_thread_data *td;
 341        struct task_struct *tsk;
 342        char *curr = buf;
 343        int i;
 344
 345        td = container_of(dev, struct test_thread_data, dev);
 346        tsk = threads[td->dev.id];
 347
 348        spin_lock(&rttest_lock);
 349
 350        curr += sprintf(curr,
 351                "O: %4d, E:%8d, S: 0x%08lx, P: %4d, N: %4d, B: %p, M:",
 352                td->opcode, td->event, tsk->state,
 353                        (MAX_RT_PRIO - 1) - tsk->prio,
 354                        (MAX_RT_PRIO - 1) - tsk->normal_prio,
 355                tsk->pi_blocked_on);
 356
 357        for (i = MAX_RT_TEST_MUTEXES - 1; i >=0 ; i--)
 358                curr += sprintf(curr, "%d", td->mutexes[i]);
 359
 360        spin_unlock(&rttest_lock);
 361
 362        curr += sprintf(curr, ", T: %p, R: %p\n", tsk,
 363                        mutexes[td->dev.id].owner);
 364
 365        return curr - buf;
 366}
 367
 368static DEVICE_ATTR(status, 0600, sysfs_test_status, NULL);
 369static DEVICE_ATTR(command, 0600, NULL, sysfs_test_command);
 370
 371static struct bus_type rttest_subsys = {
 372        .name = "rttest",
 373        .dev_name = "rttest",
 374};
 375
 376static int init_test_thread(int id)
 377{
 378        thread_data[id].dev.bus = &rttest_subsys;
 379        thread_data[id].dev.id = id;
 380
 381        threads[id] = kthread_run(test_func, &thread_data[id], "rt-test-%d", id);
 382        if (IS_ERR(threads[id]))
 383                return PTR_ERR(threads[id]);
 384
 385        return device_register(&thread_data[id].dev);
 386}
 387
 388static int init_rttest(void)
 389{
 390        int ret, i;
 391
 392        spin_lock_init(&rttest_lock);
 393
 394        for (i = 0; i < MAX_RT_TEST_MUTEXES; i++)
 395                rt_mutex_init(&mutexes[i]);
 396
 397        ret = subsys_system_register(&rttest_subsys, NULL);
 398        if (ret)
 399                return ret;
 400
 401        for (i = 0; i < MAX_RT_TEST_THREADS; i++) {
 402                ret = init_test_thread(i);
 403                if (ret)
 404                        break;
 405                ret = device_create_file(&thread_data[i].dev, &dev_attr_status);
 406                if (ret)
 407                        break;
 408                ret = device_create_file(&thread_data[i].dev, &dev_attr_command);
 409                if (ret)
 410                        break;
 411        }
 412
 413        printk("Initializing RT-Tester: %s\n", ret ? "Failed" : "OK" );
 414
 415        return ret;
 416}
 417
 418device_initcall(init_rttest);
 419
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