kernel/scftorture.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 //
   3 // Torture test for smp_call_function() and friends.
   4 //
   5 // Copyright (C) Facebook, 2020.
   6 //
   7 // Author: Paul E. McKenney <paulmck@kernel.org>
   8
   9 #define pr_fmt(fmt) fmt
  10
  11 #include <linux/atomic.h>
  12 #include <linux/bitops.h>
  13 #include <linux/completion.h>
  14 #include <linux/cpu.h>
  15 #include <linux/delay.h>
  16 #include <linux/err.h>
  17 #include <linux/init.h>
  18 #include <linux/interrupt.h>
  19 #include <linux/kthread.h>
  20 #include <linux/kernel.h>
  21 #include <linux/mm.h>
  22 #include <linux/module.h>
  23 #include <linux/moduleparam.h>
  24 #include <linux/notifier.h>
  25 #include <linux/percpu.h>
  26 #include <linux/rcupdate.h>
  27 #include <linux/rcupdate_trace.h>
  28 #include <linux/reboot.h>
  29 #include <linux/sched.h>
  30 #include <linux/spinlock.h>
  31 #include <linux/smp.h>
  32 #include <linux/stat.h>
  33 #include <linux/srcu.h>
  34 #include <linux/slab.h>
  35 #include <linux/torture.h>
  36 #include <linux/types.h>
  37
  38 #define SCFTORT_STRING "scftorture"
  39 #define SCFTORT_FLAG SCFTORT_STRING ": "
  40
  41 #define SCFTORTOUT(s, x...) \
  42         pr_alert(SCFTORT_FLAG s, ## x)
  43
  44 #define VERBOSE_SCFTORTOUT(s, x...) \
  45         do { if (verbose) pr_alert(SCFTORT_FLAG s, ## x); } while (0)
  46
  47 #define VERBOSE_SCFTORTOUT_ERRSTRING(s, x...) \
  48         do { if (verbose) pr_alert(SCFTORT_FLAG "!!! " s, ## x); } while (0)
  49
  50 MODULE_LICENSE("GPL");
  51 MODULE_AUTHOR("Paul E. McKenney <paulmck@kernel.org>");
  52
  53 // Wait until there are multiple CPUs before starting test.
  54 torture_param(int, holdoff, IS_BUILTIN(CONFIG_SCF_TORTURE_TEST) ? 10 : 0,
  55               "Holdoff time before test start (s)");
  56 torture_param(int, longwait, 0, "Include ridiculously long waits? (seconds)");
  57 torture_param(int, nthreads, -1, "# threads, defaults to -1 for all CPUs.");
  58 torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)");
  59 torture_param(int, onoff_interval, 0, "Time between CPU hotplugs (s), 0=disable");
  60 torture_param(int, shutdown_secs, 0, "Shutdown time (ms), <= zero to disable.");
  61 torture_param(int, stat_interval, 60, "Number of seconds between stats printk()s.");
  62 torture_param(int, stutter_cpus, 5, "Number of jiffies to change CPUs under test, 0=disable");
  63 torture_param(bool, use_cpus_read_lock, 0, "Use cpus_read_lock() to exclude CPU hotplug.");
  64 torture_param(int, verbose, 0, "Enable verbose debugging printk()s");
  65 torture_param(int, weight_single, -1, "Testing weight for single-CPU no-wait operations.");
  66 torture_param(int, weight_single_wait, -1, "Testing weight for single-CPU operations.");
  67 torture_param(int, weight_many, -1, "Testing weight for multi-CPU no-wait operations.");
  68 torture_param(int, weight_many_wait, -1, "Testing weight for multi-CPU operations.");
  69 torture_param(int, weight_all, -1, "Testing weight for all-CPU no-wait operations.");
  70 torture_param(int, weight_all_wait, -1, "Testing weight for all-CPU operations.");
  71
  72 char *torture_type = "";
  73
  74 #ifdef MODULE
  75 # define SCFTORT_SHUTDOWN 0
  76 #else
  77 # define SCFTORT_SHUTDOWN 1
  78 #endif
  79
  80 torture_param(bool, shutdown, SCFTORT_SHUTDOWN, "Shutdown at end of torture test.");
  81
  82 struct scf_statistics {
  83         struct task_struct *task;
  84         int cpu;
  85         long long n_single;
  86         long long n_single_ofl;
  87         long long n_single_wait;
  88         long long n_single_wait_ofl;
  89         long long n_many;
  90         long long n_many_wait;
  91         long long n_all;
  92         long long n_all_wait;
  93 };
  94
  95 static struct scf_statistics *scf_stats_p;
  96 static struct task_struct *scf_torture_stats_task;
  97 static DEFINE_PER_CPU(long long, scf_invoked_count);
  98
  99 // Data for random primitive selection
 100 #define SCF_PRIM_SINGLE         0
 101 #define SCF_PRIM_MANY           1
 102 #define SCF_PRIM_ALL            2
 103 #define SCF_NPRIMS              (2 * 3) // Need wait and no-wait versions of each.
 104
 105 static char *scf_prim_name[] = {
 106         "smp_call_function_single",
 107         "smp_call_function_many",
 108         "smp_call_function",
 109 };
 110
 111 struct scf_selector {
 112         unsigned long scfs_weight;
 113         int scfs_prim;
 114         bool scfs_wait;
 115 };
 116 static struct scf_selector scf_sel_array[SCF_NPRIMS];
 117 static int scf_sel_array_len;
 118 static unsigned long scf_sel_totweight;
 119
 120 // Communicate between caller and handler.
 121 struct scf_check {
 122         bool scfc_in;
 123         bool scfc_out;
 124         int scfc_cpu; // -1 for not _single().
 125         bool scfc_wait;
 126 };
 127
 128 // Use to wait for all threads to start.
 129 static atomic_t n_started;
 130 static atomic_t n_errs;
 131 static atomic_t n_mb_in_errs;
 132 static atomic_t n_mb_out_errs;
 133 static atomic_t n_alloc_errs;
 134 static bool scfdone;
 135 static char *bangstr = "";
 136
 137 static DEFINE_TORTURE_RANDOM_PERCPU(scf_torture_rand);
 138
 139 // Print torture statistics.  Caller must ensure serialization.
 140 static void scf_torture_stats_print(void)
 141 {
 142         int cpu;
 143         int i;
 144         long long invoked_count = 0;
 145         bool isdone = READ_ONCE(scfdone);
 146         struct scf_statistics scfs = {};
 147
 148         for_each_possible_cpu(cpu)
 149                 invoked_count += data_race(per_cpu(scf_invoked_count, cpu));
 150         for (i = 0; i < nthreads; i++) {
 151                 scfs.n_single += scf_stats_p[i].n_single;
 152                 scfs.n_single_ofl += scf_stats_p[i].n_single_ofl;
 153                 scfs.n_single_wait += scf_stats_p[i].n_single_wait;
 154                 scfs.n_single_wait_ofl += scf_stats_p[i].n_single_wait_ofl;
 155                 scfs.n_many += scf_stats_p[i].n_many;
 156                 scfs.n_many_wait += scf_stats_p[i].n_many_wait;
 157                 scfs.n_all += scf_stats_p[i].n_all;
 158                 scfs.n_all_wait += scf_stats_p[i].n_all_wait;
 159         }
 160         if (atomic_read(&n_errs) || atomic_read(&n_mb_in_errs) ||
 161             atomic_read(&n_mb_out_errs) || atomic_read(&n_alloc_errs))
 162                 bangstr = "!!! ";
 163         pr_alert("%s %sscf_invoked_count %s: %lld single: %lld/%lld single_ofl: %lld/%lld many: %lld/%lld all: %lld/%lld ",
 164                  SCFTORT_FLAG, bangstr, isdone ? "VER" : "ver", invoked_count,
 165                  scfs.n_single, scfs.n_single_wait, scfs.n_single_ofl, scfs.n_single_wait_ofl,
 166                  scfs.n_many, scfs.n_many_wait, scfs.n_all, scfs.n_all_wait);
 167         torture_onoff_stats();
 168         pr_cont("ste: %d stnmie: %d stnmoe: %d staf: %d\n", atomic_read(&n_errs),
 169                 atomic_read(&n_mb_in_errs), atomic_read(&n_mb_out_errs),
 170                 atomic_read(&n_alloc_errs));
 171 }
 172
 173 // Periodically prints torture statistics, if periodic statistics printing
 174 // was specified via the stat_interval module parameter.
 175 static int
 176 scf_torture_stats(void *arg)
 177 {
 178         VERBOSE_TOROUT_STRING("scf_torture_stats task started");
 179         do {
 180                 schedule_timeout_interruptible(stat_interval * HZ);
 181                 scf_torture_stats_print();
 182                 torture_shutdown_absorb("scf_torture_stats");
 183         } while (!torture_must_stop());
 184         torture_kthread_stopping("scf_torture_stats");
 185         return 0;
 186 }
 187
 188 // Add a primitive to the scf_sel_array[].
 189 static void scf_sel_add(unsigned long weight, int prim, bool wait)
 190 {
 191         struct scf_selector *scfsp = &scf_sel_array[scf_sel_array_len];
 192
 193         // If no weight, if array would overflow, if computing three-place
 194         // percentages would overflow, or if the scf_prim_name[] array would
 195         // overflow, don't bother.  In the last three two cases, complain.
 196         if (!weight ||
 197             WARN_ON_ONCE(scf_sel_array_len >= ARRAY_SIZE(scf_sel_array)) ||
 198             WARN_ON_ONCE(0 - 100000 * weight <= 100000 * scf_sel_totweight) ||
 199             WARN_ON_ONCE(prim >= ARRAY_SIZE(scf_prim_name)))
 200                 return;
 201         scf_sel_totweight += weight;
 202         scfsp->scfs_weight = scf_sel_totweight;
 203         scfsp->scfs_prim = prim;
 204         scfsp->scfs_wait = wait;
 205         scf_sel_array_len++;
 206 }
 207
 208 // Dump out weighting percentages for scf_prim_name[] array.
 209 static void scf_sel_dump(void)
 210 {
 211         int i;
 212         unsigned long oldw = 0;
 213         struct scf_selector *scfsp;
 214         unsigned long w;
 215
 216         for (i = 0; i < scf_sel_array_len; i++) {
 217                 scfsp = &scf_sel_array[i];
 218                 w = (scfsp->scfs_weight - oldw) * 100000 / scf_sel_totweight;
 219                 pr_info("%s: %3lu.%03lu %s(%s)\n", __func__, w / 1000, w % 1000,
 220                         scf_prim_name[scfsp->scfs_prim],
 221                         scfsp->scfs_wait ? "wait" : "nowait");
 222                 oldw = scfsp->scfs_weight;
 223         }
 224 }
 225
 226 // Randomly pick a primitive and wait/nowait, based on weightings.
 227 static struct scf_selector *scf_sel_rand(struct torture_random_state *trsp)
 228 {
 229         int i;
 230         unsigned long w = torture_random(trsp) % (scf_sel_totweight + 1);
 231
 232         for (i = 0; i < scf_sel_array_len; i++)
 233                 if (scf_sel_array[i].scfs_weight >= w)
 234                         return &scf_sel_array[i];
 235         WARN_ON_ONCE(1);
 236         return &scf_sel_array[0];
 237 }
 238
 239 // Update statistics and occasionally burn up mass quantities of CPU time,
 240 // if told to do so via scftorture.longwait.  Otherwise, occasionally burn
 241 // a little bit.
 242 static void scf_handler(void *scfc_in)
 243 {
 244         int i;
 245         int j;
 246         unsigned long r = torture_random(this_cpu_ptr(&scf_torture_rand));
 247         struct scf_check *scfcp = scfc_in;
 248
 249         if (likely(scfcp)) {
 250                 WRITE_ONCE(scfcp->scfc_out, false); // For multiple receivers.
 251                 if (WARN_ON_ONCE(unlikely(!READ_ONCE(scfcp->scfc_in))))
 252                         atomic_inc(&n_mb_in_errs);
 253         }
 254         this_cpu_inc(scf_invoked_count);
 255         if (longwait <= 0) {
 256                 if (!(r & 0xffc0))
 257                         udelay(r & 0x3f);
 258                 goto out;
 259         }
 260         if (r & 0xfff)
 261                 goto out;
 262         r = (r >> 12);
 263         if (longwait <= 0) {
 264                 udelay((r & 0xff) + 1);
 265                 goto out;
 266         }
 267         r = r % longwait + 1;
 268         for (i = 0; i < r; i++) {
 269                 for (j = 0; j < 1000; j++) {
 270                         udelay(1000);
 271                         cpu_relax();
 272                 }
 273         }
 274 out:
 275         if (unlikely(!scfcp))
 276                 return;
 277         if (scfcp->scfc_wait)
 278                 WRITE_ONCE(scfcp->scfc_out, true);
 279         else
 280                 kfree(scfcp);
 281 }
 282
 283 // As above, but check for correct CPU.
 284 static void scf_handler_1(void *scfc_in)
 285 {
 286         struct scf_check *scfcp = scfc_in;
 287
 288         if (likely(scfcp) && WARN_ONCE(smp_processor_id() != scfcp->scfc_cpu, "%s: Wanted CPU %d got CPU %d\n", __func__, scfcp->scfc_cpu, smp_processor_id())) {
 289                 atomic_inc(&n_errs);
 290         }
 291         scf_handler(scfcp);
 292 }
 293
 294 // Randomly do an smp_call_function*() invocation.
 295 static void scftorture_invoke_one(struct scf_statistics *scfp, struct torture_random_state *trsp)
 296 {
 297         uintptr_t cpu;
 298         int ret = 0;
 299         struct scf_check *scfcp = NULL;
 300         struct scf_selector *scfsp = scf_sel_rand(trsp);
 301
 302         if (use_cpus_read_lock)
 303                 cpus_read_lock();
 304         else
 305                 preempt_disable();
 306         if (scfsp->scfs_prim == SCF_PRIM_SINGLE || scfsp->scfs_wait) {
 307                 scfcp = kmalloc(sizeof(*scfcp), GFP_ATOMIC);
 308                 if (WARN_ON_ONCE(!scfcp)) {
 309                         atomic_inc(&n_alloc_errs);
 310                 } else {
 311                         scfcp->scfc_cpu = -1;
 312                         scfcp->scfc_wait = scfsp->scfs_wait;
 313                         scfcp->scfc_out = false;
 314                 }
 315         }
 316         switch (scfsp->scfs_prim) {
 317         case SCF_PRIM_SINGLE:
 318                 cpu = torture_random(trsp) % nr_cpu_ids;
 319                 if (scfsp->scfs_wait)
 320                         scfp->n_single_wait++;
 321                 else
 322                         scfp->n_single++;
 323                 if (scfcp) {
 324                         scfcp->scfc_cpu = cpu;
 325                         barrier(); // Prevent race-reduction compiler optimizations.
 326                         scfcp->scfc_in = true;
 327                 }
 328                 ret = smp_call_function_single(cpu, scf_handler_1, (void *)scfcp, scfsp->scfs_wait);
 329                 if (ret) {
 330                         if (scfsp->scfs_wait)
 331                                 scfp->n_single_wait_ofl++;
 332                         else
 333                                 scfp->n_single_ofl++;
 334                         kfree(scfcp);
 335                         scfcp = NULL;
 336                 }
 337                 break;
 338         case SCF_PRIM_MANY:
 339                 if (scfsp->scfs_wait)
 340                         scfp->n_many_wait++;
 341                 else
 342                         scfp->n_many++;
 343                 if (scfcp) {
 344                         barrier(); // Prevent race-reduction compiler optimizations.
 345                         scfcp->scfc_in = true;
 346                 }
 347                 smp_call_function_many(cpu_online_mask, scf_handler, scfcp, scfsp->scfs_wait);
 348                 break;
 349         case SCF_PRIM_ALL:
 350                 if (scfsp->scfs_wait)
 351                         scfp->n_all_wait++;
 352                 else
 353                         scfp->n_all++;
 354                 if (scfcp) {
 355                         barrier(); // Prevent race-reduction compiler optimizations.
 356                         scfcp->scfc_in = true;
 357                 }
 358                 smp_call_function(scf_handler, scfcp, scfsp->scfs_wait);
 359                 break;
 360         default:
 361                 WARN_ON_ONCE(1);
 362                 if (scfcp)
 363                         scfcp->scfc_out = true;
 364         }
 365         if (scfcp && scfsp->scfs_wait) {
 366                 if (WARN_ON_ONCE((num_online_cpus() > 1 || scfsp->scfs_prim == SCF_PRIM_SINGLE) &&
 367                                  !scfcp->scfc_out))
 368                         atomic_inc(&n_mb_out_errs); // Leak rather than trash!
 369                 else
 370                         kfree(scfcp);
 371                 barrier(); // Prevent race-reduction compiler optimizations.
 372         }
 373         if (use_cpus_read_lock)
 374                 cpus_read_unlock();
 375         else
 376                 preempt_enable();
 377         if (!(torture_random(trsp) & 0xfff))
 378                 schedule_timeout_uninterruptible(1);
 379 }
 380
 381 // SCF test kthread.  Repeatedly does calls to members of the
 382 // smp_call_function() family of functions.
 383 static int scftorture_invoker(void *arg)
 384 {
 385         int cpu;
 386         DEFINE_TORTURE_RANDOM(rand);
 387         struct scf_statistics *scfp = (struct scf_statistics *)arg;
 388         bool was_offline = false;
 389
 390         VERBOSE_SCFTORTOUT("scftorture_invoker %d: task started", scfp->cpu);
 391         cpu = scfp->cpu % nr_cpu_ids;
 392         set_cpus_allowed_ptr(current, cpumask_of(cpu));
 393         set_user_nice(current, MAX_NICE);
 394         if (holdoff)
 395                 schedule_timeout_interruptible(holdoff * HZ);
 396
 397         VERBOSE_SCFTORTOUT("scftorture_invoker %d: Waiting for all SCF torturers from cpu %d", scfp->cpu, smp_processor_id());
 398
 399         // Make sure that the CPU is affinitized appropriately during testing.
 400         WARN_ON_ONCE(smp_processor_id() != scfp->cpu);
 401
 402         if (!atomic_dec_return(&n_started))
 403                 while (atomic_read_acquire(&n_started)) {
 404                         if (torture_must_stop()) {
 405                                 VERBOSE_SCFTORTOUT("scftorture_invoker %d ended before starting", scfp->cpu);
 406                                 goto end;
 407                         }
 408                         schedule_timeout_uninterruptible(1);
 409                 }
 410
 411         VERBOSE_SCFTORTOUT("scftorture_invoker %d started", scfp->cpu);
 412
 413         do {
 414                 scftorture_invoke_one(scfp, &rand);
 415                 while (cpu_is_offline(cpu) && !torture_must_stop()) {
 416                         schedule_timeout_interruptible(HZ / 5);
 417                         was_offline = true;
 418                 }
 419                 if (was_offline) {
 420                         set_cpus_allowed_ptr(current, cpumask_of(cpu));
 421                         was_offline = false;
 422                 }
 423                 cond_resched();
 424         } while (!torture_must_stop());
 425
 426         VERBOSE_SCFTORTOUT("scftorture_invoker %d ended", scfp->cpu);
 427 end:
 428         torture_kthread_stopping("scftorture_invoker");
 429         return 0;
 430 }
 431
 432 static void
 433 scftorture_print_module_parms(const char *tag)
 434 {
 435         pr_alert(SCFTORT_FLAG
 436                  "--- %s:  verbose=%d holdoff=%d longwait=%d nthreads=%d onoff_holdoff=%d onoff_interval=%d shutdown_secs=%d stat_interval=%d stutter_cpus=%d use_cpus_read_lock=%d, weight_single=%d, weight_single_wait=%d, weight_many=%d, weight_many_wait=%d, weight_all=%d, weight_all_wait=%d\n", tag,
 437                  verbose, holdoff, longwait, nthreads, onoff_holdoff, onoff_interval, shutdown, stat_interval, stutter_cpus, use_cpus_read_lock, weight_single, weight_single_wait, weight_many, weight_many_wait, weight_all, weight_all_wait);
 438 }
 439
 440 static void scf_cleanup_handler(void *unused)
 441 {
 442 }
 443
 444 static void scf_torture_cleanup(void)
 445 {
 446         int i;
 447
 448         if (torture_cleanup_begin())
 449                 return;
 450
 451         WRITE_ONCE(scfdone, true);
 452         if (nthreads)
 453                 for (i = 0; i < nthreads; i++)
 454                         torture_stop_kthread("scftorture_invoker", scf_stats_p[i].task);
 455         else
 456                 goto end;
 457         smp_call_function(scf_cleanup_handler, NULL, 0);
 458         torture_stop_kthread(scf_torture_stats, scf_torture_stats_task);
 459         scf_torture_stats_print();  // -After- the stats thread is stopped!
 460         kfree(scf_stats_p);  // -After- the last stats print has completed!
 461         scf_stats_p = NULL;
 462
 463         if (atomic_read(&n_errs) || atomic_read(&n_mb_in_errs) || atomic_read(&n_mb_out_errs))
 464                 scftorture_print_module_parms("End of test: FAILURE");
 465         else if (torture_onoff_failures())
 466                 scftorture_print_module_parms("End of test: LOCK_HOTPLUG");
 467         else
 468                 scftorture_print_module_parms("End of test: SUCCESS");
 469
 470 end:
 471         torture_cleanup_end();
 472 }
 473
 474 static int __init scf_torture_init(void)
 475 {
 476         long i;
 477         int firsterr = 0;
 478         unsigned long weight_single1 = weight_single;
 479         unsigned long weight_single_wait1 = weight_single_wait;
 480         unsigned long weight_many1 = weight_many;
 481         unsigned long weight_many_wait1 = weight_many_wait;
 482         unsigned long weight_all1 = weight_all;
 483         unsigned long weight_all_wait1 = weight_all_wait;
 484
 485         if (!torture_init_begin(SCFTORT_STRING, verbose))
 486                 return -EBUSY;
 487
 488         scftorture_print_module_parms("Start of test");
 489
 490         if (weight_single == -1 && weight_single_wait == -1 &&
 491             weight_many == -1 && weight_many_wait == -1 &&
 492             weight_all == -1 && weight_all_wait == -1) {
 493                 weight_single1 = 2 * nr_cpu_ids;
 494                 weight_single_wait1 = 2 * nr_cpu_ids;
 495                 weight_many1 = 2;
 496                 weight_many_wait1 = 2;
 497                 weight_all1 = 1;
 498                 weight_all_wait1 = 1;
 499         } else {
 500                 if (weight_single == -1)
 501                         weight_single1 = 0;
 502                 if (weight_single_wait == -1)
 503                         weight_single_wait1 = 0;
 504                 if (weight_many == -1)
 505                         weight_many1 = 0;
 506                 if (weight_many_wait == -1)
 507                         weight_many_wait1 = 0;
 508                 if (weight_all == -1)
 509                         weight_all1 = 0;
 510                 if (weight_all_wait == -1)
 511                         weight_all_wait1 = 0;
 512         }
 513         if (weight_single1 == 0 && weight_single_wait1 == 0 &&
 514             weight_many1 == 0 && weight_many_wait1 == 0 &&
 515             weight_all1 == 0 && weight_all_wait1 == 0) {
 516                 VERBOSE_SCFTORTOUT_ERRSTRING("all zero weights makes no sense");
 517                 firsterr = -EINVAL;
 518                 goto unwind;
 519         }
 520         scf_sel_add(weight_single1, SCF_PRIM_SINGLE, false);
 521         scf_sel_add(weight_single_wait1, SCF_PRIM_SINGLE, true);
 522         scf_sel_add(weight_many1, SCF_PRIM_MANY, false);
 523         scf_sel_add(weight_many_wait1, SCF_PRIM_MANY, true);
 524         scf_sel_add(weight_all1, SCF_PRIM_ALL, false);
 525         scf_sel_add(weight_all_wait1, SCF_PRIM_ALL, true);
 526         scf_sel_dump();
 527
 528         if (onoff_interval > 0) {
 529                 firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval, NULL);
 530                 if (firsterr)
 531                         goto unwind;
 532         }
 533         if (shutdown_secs > 0) {
 534                 firsterr = torture_shutdown_init(shutdown_secs, scf_torture_cleanup);
 535                 if (firsterr)
 536                         goto unwind;
 537         }
 538
 539         // Worker tasks invoking smp_call_function().
 540         if (nthreads < 0)
 541                 nthreads = num_online_cpus();
 542         scf_stats_p = kcalloc(nthreads, sizeof(scf_stats_p[0]), GFP_KERNEL);
 543         if (!scf_stats_p) {
 544                 VERBOSE_SCFTORTOUT_ERRSTRING("out of memory");
 545                 firsterr = -ENOMEM;
 546                 goto unwind;
 547         }
 548
 549         VERBOSE_SCFTORTOUT("Starting %d smp_call_function() threads\n", nthreads);
 550
 551         atomic_set(&n_started, nthreads);
 552         for (i = 0; i < nthreads; i++) {
 553                 scf_stats_p[i].cpu = i;
 554                 firsterr = torture_create_kthread(scftorture_invoker, (void *)&scf_stats_p[i],
 555                                                   scf_stats_p[i].task);
 556                 if (firsterr)
 557                         goto unwind;
 558         }
 559         if (stat_interval > 0) {
 560                 firsterr = torture_create_kthread(scf_torture_stats, NULL, scf_torture_stats_task);
 561                 if (firsterr)
 562                         goto unwind;
 563         }
 564
 565         torture_init_end();
 566         return 0;
 567
 568 unwind:
 569         torture_init_end();
 570         scf_torture_cleanup();
 571         return firsterr;
 572 }
 573
 574 module_init(scf_torture_init);
 575 module_exit(scf_torture_cleanup);