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