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 #ifdef CONFIG_LOCK_KERNEL
  80                         unlock_kernel();
  81 #endif
  82                         td->bkl = 0;
  83                 }
  84                 return 0;
  85
  86         case RTTEST_RESETEVENT:
  87                 atomic_set(&rttest_event, 0);
  88                 return 0;
  89
  90         default:
  91                 if (lockwakeup)
  92                         return ret;
  93         }
  94
  95         switch(td->opcode) {
  96
  97         case RTTEST_LOCK:
  98         case RTTEST_LOCKNOWAIT:
  99                 id = td->opdata;
 100                 if (id < 0 || id >= MAX_RT_TEST_MUTEXES)
 101                         return ret;
 102
 103                 td->mutexes[id] = 1;
 104                 td->event = atomic_add_return(1, &rttest_event);
 105                 rt_mutex_lock(&mutexes[id]);
 106                 td->event = atomic_add_return(1, &rttest_event);
 107                 td->mutexes[id] = 4;
 108                 return 0;
 109
 110         case RTTEST_LOCKINT:
 111         case RTTEST_LOCKINTNOWAIT:
 112                 id = td->opdata;
 113                 if (id < 0 || id >= MAX_RT_TEST_MUTEXES)
 114                         return ret;
 115
 116                 td->mutexes[id] = 1;
 117                 td->event = atomic_add_return(1, &rttest_event);
 118                 ret = rt_mutex_lock_interruptible(&mutexes[id], 0);
 119                 td->event = atomic_add_return(1, &rttest_event);
 120                 td->mutexes[id] = ret ? 0 : 4;
 121                 return ret ? -EINTR : 0;
 122
 123         case RTTEST_UNLOCK:
 124                 id = td->opdata;
 125                 if (id < 0 || id >= MAX_RT_TEST_MUTEXES || td->mutexes[id] != 4)
 126                         return ret;
 127
 128                 td->event = atomic_add_return(1, &rttest_event);
 129                 rt_mutex_unlock(&mutexes[id]);
 130                 td->event = atomic_add_return(1, &rttest_event);
 131                 td->mutexes[id] = 0;
 132                 return 0;
 133
 134         case RTTEST_LOCKBKL:
 135                 if (td->bkl)
 136                         return 0;
 137                 td->bkl = 1;
 138 #ifdef CONFIG_LOCK_KERNEL
 139                 lock_kernel();
 140 #endif
 141                 td->bkl = 4;
 142                 return 0;
 143
 144         case RTTEST_UNLOCKBKL:
 145                 if (td->bkl != 4)
 146                         break;
 147 #ifdef CONFIG_LOCK_KERNEL
 148                 unlock_kernel();
 149 #endif
 150                 td->bkl = 0;
 151                 return 0;
 152
 153         default:
 154                 break;
 155         }
 156         return ret;
 157 }
 158
 159 /*
 160  * Schedule replacement for rtsem_down(). Only called for threads with
 161  * PF_MUTEX_TESTER set.
 162  *
 163  * This allows us to have finegrained control over the event flow.
 164  *
 165  */
 166 void schedule_rt_mutex_test(struct rt_mutex *mutex)
 167 {
 168         int tid, op, dat;
 169         struct test_thread_data *td;
 170
 171         /* We have to lookup the task */
 172         for (tid = 0; tid < MAX_RT_TEST_THREADS; tid++) {
 173                 if (threads[tid] == current)
 174                         break;
 175         }
 176
 177         BUG_ON(tid == MAX_RT_TEST_THREADS);
 178
 179         td = &thread_data[tid];
 180
 181         op = td->opcode;
 182         dat = td->opdata;
 183
 184         switch (op) {
 185         case RTTEST_LOCK:
 186         case RTTEST_LOCKINT:
 187         case RTTEST_LOCKNOWAIT:
 188         case RTTEST_LOCKINTNOWAIT:
 189                 if (mutex != &mutexes[dat])
 190                         break;
 191
 192                 if (td->mutexes[dat] != 1)
 193                         break;
 194
 195                 td->mutexes[dat] = 2;
 196                 td->event = atomic_add_return(1, &rttest_event);
 197                 break;
 198
 199         case RTTEST_LOCKBKL:
 200         default:
 201                 break;
 202         }
 203
 204         schedule();
 205
 206
 207         switch (op) {
 208         case RTTEST_LOCK:
 209         case RTTEST_LOCKINT:
 210                 if (mutex != &mutexes[dat])
 211                         return;
 212
 213                 if (td->mutexes[dat] != 2)
 214                         return;
 215
 216                 td->mutexes[dat] = 3;
 217                 td->event = atomic_add_return(1, &rttest_event);
 218                 break;
 219
 220         case RTTEST_LOCKNOWAIT:
 221         case RTTEST_LOCKINTNOWAIT:
 222                 if (mutex != &mutexes[dat])
 223                         return;
 224
 225                 if (td->mutexes[dat] != 2)
 226                         return;
 227
 228                 td->mutexes[dat] = 1;
 229                 td->event = atomic_add_return(1, &rttest_event);
 230                 return;
 231
 232         case RTTEST_LOCKBKL:
 233                 return;
 234         default:
 235                 return;
 236         }
 237
 238         td->opcode = 0;
 239
 240         for (;;) {
 241                 set_current_state(TASK_INTERRUPTIBLE);
 242
 243                 if (td->opcode > 0) {
 244                         int ret;
 245
 246                         set_current_state(TASK_RUNNING);
 247                         ret = handle_op(td, 1);
 248                         set_current_state(TASK_INTERRUPTIBLE);
 249                         if (td->opcode == RTTEST_LOCKCONT)
 250                                 break;
 251                         td->opcode = ret;
 252                 }
 253
 254                 /* Wait for the next command to be executed */
 255                 schedule();
 256         }
 257
 258         /* Restore previous command and data */
 259         td->opcode = op;
 260         td->opdata = dat;
 261 }
 262
 263 static int test_func(void *data)
 264 {
 265         struct test_thread_data *td = data;
 266         int ret;
 267
 268         current->flags |= PF_MUTEX_TESTER;
 269         set_freezable();
 270         allow_signal(SIGHUP);
 271
 272         for(;;) {
 273
 274                 set_current_state(TASK_INTERRUPTIBLE);
 275
 276                 if (td->opcode > 0) {
 277                         set_current_state(TASK_RUNNING);
 278                         ret = handle_op(td, 0);
 279                         set_current_state(TASK_INTERRUPTIBLE);
 280                         td->opcode = ret;
 281                 }
 282
 283                 /* Wait for the next command to be executed */
 284                 schedule();
 285                 try_to_freeze();
 286
 287                 if (signal_pending(current))
 288                         flush_signals(current);
 289
 290                 if(kthread_should_stop())
 291                         break;
 292         }
 293         return 0;
 294 }
 295
 296 /**
 297  * sysfs_test_command - interface for test commands
 298  * @dev:        thread reference
 299  * @buf:        command for actual step
 300  * @count:      length of buffer
 301  *
 302  * command syntax:
 303  *
 304  * opcode:data
 305  */
 306 static ssize_t sysfs_test_command(struct sys_device *dev, struct sysdev_attribute *attr,
 307                                   const char *buf, size_t count)
 308 {
 309         struct sched_param schedpar;
 310         struct test_thread_data *td;
 311         char cmdbuf[32];
 312         int op, dat, tid, ret;
 313
 314         td = container_of(dev, struct test_thread_data, sysdev);
 315         tid = td->sysdev.id;
 316
 317         /* strings from sysfs write are not 0 terminated! */
 318         if (count >= sizeof(cmdbuf))
 319                 return -EINVAL;
 320
 321         /* strip of \n: */
 322         if (buf[count-1] == '\n')
 323                 count--;
 324         if (count < 1)
 325                 return -EINVAL;
 326
 327         memcpy(cmdbuf, buf, count);
 328         cmdbuf[count] = 0;
 329
 330         if (sscanf(cmdbuf, "%d:%d", &op, &dat) != 2)
 331                 return -EINVAL;
 332
 333         switch (op) {
 334         case RTTEST_SCHEDOT:
 335                 schedpar.sched_priority = 0;
 336                 ret = sched_setscheduler(threads[tid], SCHED_NORMAL, &schedpar);
 337                 if (ret)
 338                         return ret;
 339                 set_user_nice(current, 0);
 340                 break;
 341
 342         case RTTEST_SCHEDRT:
 343                 schedpar.sched_priority = dat;
 344                 ret = sched_setscheduler(threads[tid], SCHED_FIFO, &schedpar);
 345                 if (ret)
 346                         return ret;
 347                 break;
 348
 349         case RTTEST_SIGNAL:
 350                 send_sig(SIGHUP, threads[tid], 0);
 351                 break;
 352
 353         default:
 354                 if (td->opcode > 0)
 355                         return -EBUSY;
 356                 td->opdata = dat;
 357                 td->opcode = op;
 358                 wake_up_process(threads[tid]);
 359         }
 360
 361         return count;
 362 }
 363
 364 /**
 365  * sysfs_test_status - sysfs interface for rt tester
 366  * @dev:        thread to query
 367  * @buf:        char buffer to be filled with thread status info
 368  */
 369 static ssize_t sysfs_test_status(struct sys_device *dev, struct sysdev_attribute *attr,
 370                                  char *buf)
 371 {
 372         struct test_thread_data *td;
 373         struct task_struct *tsk;
 374         char *curr = buf;
 375         int i;
 376
 377         td = container_of(dev, struct test_thread_data, sysdev);
 378         tsk = threads[td->sysdev.id];
 379
 380         spin_lock(&rttest_lock);
 381
 382         curr += sprintf(curr,
 383                 "O: %4d, E:%8d, S: 0x%08lx, P: %4d, N: %4d, B: %p, K: %d, M:",
 384                 td->opcode, td->event, tsk->state,
 385                         (MAX_RT_PRIO - 1) - tsk->prio,
 386                         (MAX_RT_PRIO - 1) - tsk->normal_prio,
 387                 tsk->pi_blocked_on, td->bkl);
 388
 389         for (i = MAX_RT_TEST_MUTEXES - 1; i >=0 ; i--)
 390                 curr += sprintf(curr, "%d", td->mutexes[i]);
 391
 392         spin_unlock(&rttest_lock);
 393
 394         curr += sprintf(curr, ", T: %p, R: %p\n", tsk,
 395                         mutexes[td->sysdev.id].owner);
 396
 397         return curr - buf;
 398 }
 399
 400 static SYSDEV_ATTR(status, 0600, sysfs_test_status, NULL);
 401 static SYSDEV_ATTR(command, 0600, NULL, sysfs_test_command);
 402
 403 static struct sysdev_class rttest_sysclass = {
 404         .name = "rttest",
 405 };
 406
 407 static int init_test_thread(int id)
 408 {
 409         thread_data[id].sysdev.cls = &rttest_sysclass;
 410         thread_data[id].sysdev.id = id;
 411
 412         threads[id] = kthread_run(test_func, &thread_data[id], "rt-test-%d", id);
 413         if (IS_ERR(threads[id]))
 414                 return PTR_ERR(threads[id]);
 415
 416         return sysdev_register(&thread_data[id].sysdev);
 417 }
 418
 419 static int init_rttest(void)
 420 {
 421         int ret, i;
 422
 423         spin_lock_init(&rttest_lock);
 424
 425         for (i = 0; i < MAX_RT_TEST_MUTEXES; i++)
 426                 rt_mutex_init(&mutexes[i]);
 427
 428         ret = sysdev_class_register(&rttest_sysclass);
 429         if (ret)
 430                 return ret;
 431
 432         for (i = 0; i < MAX_RT_TEST_THREADS; i++) {
 433                 ret = init_test_thread(i);
 434                 if (ret)
 435                         break;
 436                 ret = sysdev_create_file(&thread_data[i].sysdev, &attr_status);
 437                 if (ret)
 438                         break;
 439                 ret = sysdev_create_file(&thread_data[i].sysdev, &attr_command);
 440                 if (ret)
 441                         break;
 442         }
 443
 444         printk("Initializing RT-Tester: %s\n", ret ? "Failed" : "OK" );
 445
 446         return ret;
 447 }
 448
 449 device_initcall(init_rttest);