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