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
  23 static spinlock_t rttest_lock;
  24 static atomic_t rttest_event;
  25
  26 struct 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
  35 static struct test_thread_data thread_data[MAX_RT_TEST_THREADS];
  36 static struct task_struct *threads[MAX_RT_TEST_THREADS];
  37 static struct rt_mutex mutexes[MAX_RT_TEST_MUTEXES];
  38
  39 enum 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
  56 static 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  */
 160 void 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
 257 static 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  */
 300 static ssize_t sysfs_test_command(struct sys_device *dev, const char *buf,
 301                                   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  */
 363 static ssize_t sysfs_test_status(struct sys_device *dev, char *buf)
 364 {
 365         struct test_thread_data *td;
 366         struct task_struct *tsk;
 367         char *curr = buf;
 368         int i;
 369
 370         td = container_of(dev, struct test_thread_data, sysdev);
 371         tsk = threads[td->sysdev.id];
 372
 373         spin_lock(&rttest_lock);
 374
 375         curr += sprintf(curr,
 376                 "O: %4d, E:%8d, S: 0x%08lx, P: %4d, N: %4d, B: %p, K: %d, M:",
 377                 td->opcode, td->event, tsk->state,
 378                         (MAX_RT_PRIO - 1) - tsk->prio,
 379                         (MAX_RT_PRIO - 1) - tsk->normal_prio,
 380                 tsk->pi_blocked_on, td->bkl);
 381
 382         for (i = MAX_RT_TEST_MUTEXES - 1; i >=0 ; i--)
 383                 curr += sprintf(curr, "%d", td->mutexes[i]);
 384
 385         spin_unlock(&rttest_lock);
 386
 387         curr += sprintf(curr, ", T: %p, R: %p\n", tsk,
 388                         mutexes[td->sysdev.id].owner);
 389
 390         return curr - buf;
 391 }
 392
 393 static SYSDEV_ATTR(status, 0600, sysfs_test_status, NULL);
 394 static SYSDEV_ATTR(command, 0600, NULL, sysfs_test_command);
 395
 396 static struct sysdev_class rttest_sysclass = {
 397         set_kset_name("rttest"),
 398 };
 399
 400 static int init_test_thread(int id)
 401 {
 402         thread_data[id].sysdev.cls = &rttest_sysclass;
 403         thread_data[id].sysdev.id = id;
 404
 405         threads[id] = kthread_run(test_func, &thread_data[id], "rt-test-%d", id);
 406         if (IS_ERR(threads[id]))
 407                 return PTR_ERR(threads[id]);
 408
 409         return sysdev_register(&thread_data[id].sysdev);
 410 }
 411
 412 static int init_rttest(void)
 413 {
 414         int ret, i;
 415
 416         spin_lock_init(&rttest_lock);
 417
 418         for (i = 0; i < MAX_RT_TEST_MUTEXES; i++)
 419                 rt_mutex_init(&mutexes[i]);
 420
 421         ret = sysdev_class_register(&rttest_sysclass);
 422         if (ret)
 423                 return ret;
 424
 425         for (i = 0; i < MAX_RT_TEST_THREADS; i++) {
 426                 ret = init_test_thread(i);
 427                 if (ret)
 428                         break;
 429                 ret = sysdev_create_file(&thread_data[i].sysdev, &attr_status);
 430                 if (ret)
 431                         break;
 432                 ret = sysdev_create_file(&thread_data[i].sysdev, &attr_command);
 433                 if (ret)
 434                         break;
 435         }
 436
 437         printk("Initializing RT-Tester: %s\n", ret ? "Failed" : "OK" );
 438
 439         return ret;
 440 }
 441
 442 device_initcall(init_rttest);