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/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
  22 static spinlock_t rttest_lock;
  23 static atomic_t rttest_event;
  24
  25 struct 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
  33 static struct test_thread_data thread_data[MAX_RT_TEST_THREADS];
  34 static struct task_struct *threads[MAX_RT_TEST_THREADS];
  35 static struct rt_mutex mutexes[MAX_RT_TEST_MUTEXES];
  36
  37 enum 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
  53 static 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  */
 137 void 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
 231 static 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  */
 274 static 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  */
 337 static 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
 368 static DEVICE_ATTR(status, 0600, sysfs_test_status, NULL);
 369 static DEVICE_ATTR(command, 0600, NULL, sysfs_test_command);
 370
 371 static struct bus_type rttest_subsys = {
 372         .name = "rttest",
 373         .dev_name = "rttest",
 374 };
 375
 376 static 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
 388 static 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
 418 device_initcall(init_rttest);