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 VERBOSE_SCFTORTOUT(s, x...) \
  42         do { if (verbose) pr_alert(SCFTORT_FLAG s "\n", ## x); } while (0)
  43
  44 #define SCFTORTOUT_ERRSTRING(s, x...) pr_alert(SCFTORT_FLAG "!!! " s "\n", ## x)
  45
  46 MODULE_LICENSE("GPL");
  47 MODULE_AUTHOR("Paul E. McKenney <paulmck@kernel.org>");
  48
  49 // Wait until there are multiple CPUs before starting test.
  50 torture_param(int, holdoff, IS_BUILTIN(CONFIG_SCF_TORTURE_TEST) ? 10 : 0,
  51               "Holdoff time before test start (s)");
  52 torture_param(int, longwait, 0, "Include ridiculously long waits? (seconds)");
  53 torture_param(int, nthreads, -1, "# threads, defaults to -1 for all CPUs.");
  54 torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)");
  55 torture_param(int, onoff_interval, 0, "Time between CPU hotplugs (s), 0=disable");
  56 torture_param(int, shutdown_secs, 0, "Shutdown time (ms), <= zero to disable.");
  57 torture_param(int, stat_interval, 60, "Number of seconds between stats printk()s.");
  58 torture_param(int, stutter, 5, "Number of jiffies to run/halt test, 0=disable");
  59 torture_param(bool, use_cpus_read_lock, 0, "Use cpus_read_lock() to exclude CPU hotplug.");
  60 torture_param(int, verbose, 0, "Enable verbose debugging printk()s");
  61 torture_param(int, weight_resched, -1, "Testing weight for resched_cpu() operations.");
  62 torture_param(int, weight_single, -1, "Testing weight for single-CPU no-wait operations.");
  63 torture_param(int, weight_single_rpc, -1, "Testing weight for single-CPU RPC operations.");
  64 torture_param(int, weight_single_wait, -1, "Testing weight for single-CPU operations.");
  65 torture_param(int, weight_many, -1, "Testing weight for multi-CPU no-wait operations.");
  66 torture_param(int, weight_many_wait, -1, "Testing weight for multi-CPU operations.");
  67 torture_param(int, weight_all, -1, "Testing weight for all-CPU no-wait operations.");
  68 torture_param(int, weight_all_wait, -1, "Testing weight for all-CPU operations.");
  69
  70 char *torture_type = "";
  71
  72 #ifdef MODULE
  73 # define SCFTORT_SHUTDOWN 0
  74 #else
  75 # define SCFTORT_SHUTDOWN 1
  76 #endif
  77
  78 torture_param(bool, shutdown, SCFTORT_SHUTDOWN, "Shutdown at end of torture test.");
  79
  80 struct scf_statistics {
  81         struct task_struct *task;
  82         int cpu;
  83         long long n_resched;
  84         long long n_single;
  85         long long n_single_ofl;
  86         long long n_single_rpc;
  87         long long n_single_rpc_ofl;
  88         long long n_single_wait;
  89         long long n_single_wait_ofl;
  90         long long n_many;
  91         long long n_many_wait;
  92         long long n_all;
  93         long long n_all_wait;
  94 };
  95
  96 static struct scf_statistics *scf_stats_p;
  97 static struct task_struct *scf_torture_stats_task;
  98 static DEFINE_PER_CPU(long long, scf_invoked_count);
  99
 100 // Data for random primitive selection
 101 #define SCF_PRIM_RESCHED        0
 102 #define SCF_PRIM_SINGLE         1
 103 #define SCF_PRIM_SINGLE_RPC     2
 104 #define SCF_PRIM_MANY           3
 105 #define SCF_PRIM_ALL            4
 106 #define SCF_NPRIMS              8 // Need wait and no-wait versions of each,
 107                                   //  except for SCF_PRIM_RESCHED and
 108                                   //  SCF_PRIM_SINGLE_RPC.
 109
 110 static char *scf_prim_name[] = {
 111         "resched_cpu",
 112         "smp_call_function_single",
 113         "smp_call_function_single_rpc",
 114         "smp_call_function_many",
 115         "smp_call_function",
 116 };
 117
 118 struct scf_selector {
 119         unsigned long scfs_weight;
 120         int scfs_prim;
 121         bool scfs_wait;
 122 };
 123 static struct scf_selector scf_sel_array[SCF_NPRIMS];
 124 static int scf_sel_array_len;
 125 static unsigned long scf_sel_totweight;
 126
 127 // Communicate between caller and handler.
 128 struct scf_check {
 129         bool scfc_in;
 130         bool scfc_out;
 131         int scfc_cpu; // -1 for not _single().
 132         bool scfc_wait;
 133         bool scfc_rpc;
 134         struct completion scfc_completion;
 135 };
 136
 137 // Use to wait for all threads to start.
 138 static atomic_t n_started;
 139 static atomic_t n_errs;
 140 static atomic_t n_mb_in_errs;
 141 static atomic_t n_mb_out_errs;
 142 static atomic_t n_alloc_errs;
 143 static bool scfdone;
 144 static char *bangstr = "";
 145
 146 static DEFINE_TORTURE_RANDOM_PERCPU(scf_torture_rand);
 147
 148 extern void resched_cpu(int cpu); // An alternative IPI vector.
 149
 150 // Print torture statistics.  Caller must ensure serialization.
 151 static void scf_torture_stats_print(void)
 152 {
 153         int cpu;
 154         int i;
 155         long long invoked_count = 0;
 156         bool isdone = READ_ONCE(scfdone);
 157         struct scf_statistics scfs = {};
 158
 159         for_each_possible_cpu(cpu)
 160                 invoked_count += data_race(per_cpu(scf_invoked_count, cpu));
 161         for (i = 0; i < nthreads; i++) {
 162                 scfs.n_resched += scf_stats_p[i].n_resched;
 163                 scfs.n_single += scf_stats_p[i].n_single;
 164                 scfs.n_single_ofl += scf_stats_p[i].n_single_ofl;
 165                 scfs.n_single_rpc += scf_stats_p[i].n_single_rpc;
 166                 scfs.n_single_wait += scf_stats_p[i].n_single_wait;
 167                 scfs.n_single_wait_ofl += scf_stats_p[i].n_single_wait_ofl;
 168                 scfs.n_many += scf_stats_p[i].n_many;
 169                 scfs.n_many_wait += scf_stats_p[i].n_many_wait;
 170                 scfs.n_all += scf_stats_p[i].n_all;
 171                 scfs.n_all_wait += scf_stats_p[i].n_all_wait;
 172         }
 173         if (atomic_read(&n_errs) || atomic_read(&n_mb_in_errs) ||
 174             atomic_read(&n_mb_out_errs) ||
 175             (!IS_ENABLED(CONFIG_KASAN) && atomic_read(&n_alloc_errs)))
 176                 bangstr = "!!! ";
 177         pr_alert("%s %sscf_invoked_count %s: %lld resched: %lld single: %lld/%lld single_ofl: %lld/%lld single_rpc: %lld single_rpc_ofl: %lld many: %lld/%lld all: %lld/%lld ",
 178                  SCFTORT_FLAG, bangstr, isdone ? "VER" : "ver", invoked_count, scfs.n_resched,
 179                  scfs.n_single, scfs.n_single_wait, scfs.n_single_ofl, scfs.n_single_wait_ofl,
 180                  scfs.n_single_rpc, scfs.n_single_rpc_ofl,
 181                  scfs.n_many, scfs.n_many_wait, scfs.n_all, scfs.n_all_wait);
 182         torture_onoff_stats();
 183         pr_cont("ste: %d stnmie: %d stnmoe: %d staf: %d\n", atomic_read(&n_errs),
 184                 atomic_read(&n_mb_in_errs), atomic_read(&n_mb_out_errs),
 185                 atomic_read(&n_alloc_errs));
 186 }
 187
 188 // Periodically prints torture statistics, if periodic statistics printing
 189 // was specified via the stat_interval module parameter.
 190 static int
 191 scf_torture_stats(void *arg)
 192 {
 193         VERBOSE_TOROUT_STRING("scf_torture_stats task started");
 194         do {
 195                 schedule_timeout_interruptible(stat_interval * HZ);
 196                 scf_torture_stats_print();
 197                 torture_shutdown_absorb("scf_torture_stats");
 198         } while (!torture_must_stop());
 199         torture_kthread_stopping("scf_torture_stats");
 200         return 0;
 201 }
 202
 203 // Add a primitive to the scf_sel_array[].
 204 static void scf_sel_add(unsigned long weight, int prim, bool wait)
 205 {
 206         struct scf_selector *scfsp = &scf_sel_array[scf_sel_array_len];
 207
 208         // If no weight, if array would overflow, if computing three-place
 209         // percentages would overflow, or if the scf_prim_name[] array would
 210         // overflow, don't bother.  In the last three two cases, complain.
 211         if (!weight ||
 212             WARN_ON_ONCE(scf_sel_array_len >= ARRAY_SIZE(scf_sel_array)) ||
 213             WARN_ON_ONCE(0 - 100000 * weight <= 100000 * scf_sel_totweight) ||
 214             WARN_ON_ONCE(prim >= ARRAY_SIZE(scf_prim_name)))
 215                 return;
 216         scf_sel_totweight += weight;
 217         scfsp->scfs_weight = scf_sel_totweight;
 218         scfsp->scfs_prim = prim;
 219         scfsp->scfs_wait = wait;
 220         scf_sel_array_len++;
 221 }
 222
 223 // Dump out weighting percentages for scf_prim_name[] array.
 224 static void scf_sel_dump(void)
 225 {
 226         int i;
 227         unsigned long oldw = 0;
 228         struct scf_selector *scfsp;
 229         unsigned long w;
 230
 231         for (i = 0; i < scf_sel_array_len; i++) {
 232                 scfsp = &scf_sel_array[i];
 233                 w = (scfsp->scfs_weight - oldw) * 100000 / scf_sel_totweight;
 234                 pr_info("%s: %3lu.%03lu %s(%s)\n", __func__, w / 1000, w % 1000,
 235                         scf_prim_name[scfsp->scfs_prim],
 236                         scfsp->scfs_wait ? "wait" : "nowait");
 237                 oldw = scfsp->scfs_weight;
 238         }
 239 }
 240
 241 // Randomly pick a primitive and wait/nowait, based on weightings.
 242 static struct scf_selector *scf_sel_rand(struct torture_random_state *trsp)
 243 {
 244         int i;
 245         unsigned long w = torture_random(trsp) % (scf_sel_totweight + 1);
 246
 247         for (i = 0; i < scf_sel_array_len; i++)
 248                 if (scf_sel_array[i].scfs_weight >= w)
 249                         return &scf_sel_array[i];
 250         WARN_ON_ONCE(1);
 251         return &scf_sel_array[0];
 252 }
 253
 254 // Update statistics and occasionally burn up mass quantities of CPU time,
 255 // if told to do so via scftorture.longwait.  Otherwise, occasionally burn
 256 // a little bit.
 257 static void scf_handler(void *scfc_in)
 258 {
 259         int i;
 260         int j;
 261         unsigned long r = torture_random(this_cpu_ptr(&scf_torture_rand));
 262         struct scf_check *scfcp = scfc_in;
 263
 264         if (likely(scfcp)) {
 265                 WRITE_ONCE(scfcp->scfc_out, false); // For multiple receivers.
 266                 if (WARN_ON_ONCE(unlikely(!READ_ONCE(scfcp->scfc_in))))
 267                         atomic_inc(&n_mb_in_errs);
 268         }
 269         this_cpu_inc(scf_invoked_count);
 270         if (longwait <= 0) {
 271                 if (!(r & 0xffc0)) {
 272                         udelay(r & 0x3f);
 273                         goto out;
 274                 }
 275         }
 276         if (r & 0xfff)
 277                 goto out;
 278         r = (r >> 12);
 279         if (longwait <= 0) {
 280                 udelay((r & 0xff) + 1);
 281                 goto out;
 282         }
 283         r = r % longwait + 1;
 284         for (i = 0; i < r; i++) {
 285                 for (j = 0; j < 1000; j++) {
 286                         udelay(1000);
 287                         cpu_relax();
 288                 }
 289         }
 290 out:
 291         if (unlikely(!scfcp))
 292                 return;
 293         if (scfcp->scfc_wait) {
 294                 WRITE_ONCE(scfcp->scfc_out, true);
 295                 if (scfcp->scfc_rpc)
 296                         complete(&scfcp->scfc_completion);
 297         } else {
 298                 kfree(scfcp);
 299         }
 300 }
 301
 302 // As above, but check for correct CPU.
 303 static void scf_handler_1(void *scfc_in)
 304 {
 305         struct scf_check *scfcp = scfc_in;
 306
 307         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())) {
 308                 atomic_inc(&n_errs);
 309         }
 310         scf_handler(scfcp);
 311 }
 312
 313 // Randomly do an smp_call_function*() invocation.
 314 static void scftorture_invoke_one(struct scf_statistics *scfp, struct torture_random_state *trsp)
 315 {
 316         uintptr_t cpu;
 317         int ret = 0;
 318         struct scf_check *scfcp = NULL;
 319         struct scf_selector *scfsp = scf_sel_rand(trsp);
 320
 321         if (use_cpus_read_lock)
 322                 cpus_read_lock();
 323         else
 324                 preempt_disable();
 325         if (scfsp->scfs_prim == SCF_PRIM_SINGLE || scfsp->scfs_wait) {
 326                 scfcp = kmalloc(sizeof(*scfcp), GFP_ATOMIC);
 327                 if (!scfcp) {
 328                         WARN_ON_ONCE(!IS_ENABLED(CONFIG_KASAN));
 329                         atomic_inc(&n_alloc_errs);
 330                 } else {
 331                         scfcp->scfc_cpu = -1;
 332                         scfcp->scfc_wait = scfsp->scfs_wait;
 333                         scfcp->scfc_out = false;
 334                         scfcp->scfc_rpc = false;
 335                 }
 336         }
 337         switch (scfsp->scfs_prim) {
 338         case SCF_PRIM_RESCHED:
 339                 if (IS_BUILTIN(CONFIG_SCF_TORTURE_TEST)) {
 340                         cpu = torture_random(trsp) % nr_cpu_ids;
 341                         scfp->n_resched++;
 342                         resched_cpu(cpu);
 343                         this_cpu_inc(scf_invoked_count);
 344                 }
 345                 break;
 346         case SCF_PRIM_SINGLE:
 347                 cpu = torture_random(trsp) % nr_cpu_ids;
 348                 if (scfsp->scfs_wait)
 349                         scfp->n_single_wait++;
 350                 else
 351                         scfp->n_single++;
 352                 if (scfcp) {
 353                         scfcp->scfc_cpu = cpu;
 354                         barrier(); // Prevent race-reduction compiler optimizations.
 355                         scfcp->scfc_in = true;
 356                 }
 357                 ret = smp_call_function_single(cpu, scf_handler_1, (void *)scfcp, scfsp->scfs_wait);
 358                 if (ret) {
 359                         if (scfsp->scfs_wait)
 360                                 scfp->n_single_wait_ofl++;
 361                         else
 362                                 scfp->n_single_ofl++;
 363                         kfree(scfcp);
 364                         scfcp = NULL;
 365                 }
 366                 break;
 367         case SCF_PRIM_SINGLE_RPC:
 368                 if (!scfcp)
 369                         break;
 370                 cpu = torture_random(trsp) % nr_cpu_ids;
 371                 scfp->n_single_rpc++;
 372                 scfcp->scfc_cpu = cpu;
 373                 scfcp->scfc_wait = true;
 374                 init_completion(&scfcp->scfc_completion);
 375                 scfcp->scfc_rpc = true;
 376                 barrier(); // Prevent race-reduction compiler optimizations.
 377                 scfcp->scfc_in = true;
 378                 ret = smp_call_function_single(cpu, scf_handler_1, (void *)scfcp, 0);
 379                 if (!ret) {
 380                         if (use_cpus_read_lock)
 381                                 cpus_read_unlock();
 382                         else
 383                                 preempt_enable();
 384                         wait_for_completion(&scfcp->scfc_completion);
 385                         if (use_cpus_read_lock)
 386                                 cpus_read_lock();
 387                         else
 388                                 preempt_disable();
 389                 } else {
 390                         scfp->n_single_rpc_ofl++;
 391                         kfree(scfcp);
 392                         scfcp = NULL;
 393                 }
 394                 break;
 395         case SCF_PRIM_MANY:
 396                 if (scfsp->scfs_wait)
 397                         scfp->n_many_wait++;
 398                 else
 399                         scfp->n_many++;
 400                 if (scfcp) {
 401                         barrier(); // Prevent race-reduction compiler optimizations.
 402                         scfcp->scfc_in = true;
 403                 }
 404                 smp_call_function_many(cpu_online_mask, scf_handler, scfcp, scfsp->scfs_wait);
 405                 break;
 406         case SCF_PRIM_ALL:
 407                 if (scfsp->scfs_wait)
 408                         scfp->n_all_wait++;
 409                 else
 410                         scfp->n_all++;
 411                 if (scfcp) {
 412                         barrier(); // Prevent race-reduction compiler optimizations.
 413                         scfcp->scfc_in = true;
 414                 }
 415                 smp_call_function(scf_handler, scfcp, scfsp->scfs_wait);
 416                 break;
 417         default:
 418                 WARN_ON_ONCE(1);
 419                 if (scfcp)
 420                         scfcp->scfc_out = true;
 421         }
 422         if (scfcp && scfsp->scfs_wait) {
 423                 if (WARN_ON_ONCE((num_online_cpus() > 1 || scfsp->scfs_prim == SCF_PRIM_SINGLE) &&
 424                                  !scfcp->scfc_out)) {
 425                         pr_warn("%s: Memory-ordering failure, scfs_prim: %d.\n", __func__, scfsp->scfs_prim);
 426                         atomic_inc(&n_mb_out_errs); // Leak rather than trash!
 427                 } else {
 428                         kfree(scfcp);
 429                 }
 430                 barrier(); // Prevent race-reduction compiler optimizations.
 431         }
 432         if (use_cpus_read_lock)
 433                 cpus_read_unlock();
 434         else
 435                 preempt_enable();
 436         if (!(torture_random(trsp) & 0xfff))
 437                 schedule_timeout_uninterruptible(1);
 438 }
 439
 440 // SCF test kthread.  Repeatedly does calls to members of the
 441 // smp_call_function() family of functions.
 442 static int scftorture_invoker(void *arg)
 443 {
 444         int cpu;
 445         int curcpu;
 446         DEFINE_TORTURE_RANDOM(rand);
 447         struct scf_statistics *scfp = (struct scf_statistics *)arg;
 448         bool was_offline = false;
 449
 450         VERBOSE_SCFTORTOUT("scftorture_invoker %d: task started", scfp->cpu);
 451         cpu = scfp->cpu % nr_cpu_ids;
 452         WARN_ON_ONCE(set_cpus_allowed_ptr(current, cpumask_of(cpu)));
 453         set_user_nice(current, MAX_NICE);
 454         if (holdoff)
 455                 schedule_timeout_interruptible(holdoff * HZ);
 456
 457         VERBOSE_SCFTORTOUT("scftorture_invoker %d: Waiting for all SCF torturers from cpu %d", scfp->cpu, raw_smp_processor_id());
 458
 459         // Make sure that the CPU is affinitized appropriately during testing.
 460         curcpu = raw_smp_processor_id();
 461         WARN_ONCE(curcpu != scfp->cpu % nr_cpu_ids,
 462                   "%s: Wanted CPU %d, running on %d, nr_cpu_ids = %d\n",
 463                   __func__, scfp->cpu, curcpu, nr_cpu_ids);
 464
 465         if (!atomic_dec_return(&n_started))
 466                 while (atomic_read_acquire(&n_started)) {
 467                         if (torture_must_stop()) {
 468                                 VERBOSE_SCFTORTOUT("scftorture_invoker %d ended before starting", scfp->cpu);
 469                                 goto end;
 470                         }
 471                         schedule_timeout_uninterruptible(1);
 472                 }
 473
 474         VERBOSE_SCFTORTOUT("scftorture_invoker %d started", scfp->cpu);
 475
 476         do {
 477                 scftorture_invoke_one(scfp, &rand);
 478                 while (cpu_is_offline(cpu) && !torture_must_stop()) {
 479                         schedule_timeout_interruptible(HZ / 5);
 480                         was_offline = true;
 481                 }
 482                 if (was_offline) {
 483                         set_cpus_allowed_ptr(current, cpumask_of(cpu));
 484                         was_offline = false;
 485                 }
 486                 cond_resched();
 487                 stutter_wait("scftorture_invoker");
 488         } while (!torture_must_stop());
 489
 490         VERBOSE_SCFTORTOUT("scftorture_invoker %d ended", scfp->cpu);
 491 end:
 492         torture_kthread_stopping("scftorture_invoker");
 493         return 0;
 494 }
 495
 496 static void
 497 scftorture_print_module_parms(const char *tag)
 498 {
 499         pr_alert(SCFTORT_FLAG
 500                  "--- %s:  verbose=%d holdoff=%d longwait=%d nthreads=%d onoff_holdoff=%d onoff_interval=%d shutdown_secs=%d stat_interval=%d stutter=%d use_cpus_read_lock=%d, weight_resched=%d, weight_single=%d, weight_single_rpc=%d, weight_single_wait=%d, weight_many=%d, weight_many_wait=%d, weight_all=%d, weight_all_wait=%d\n", tag,
 501                  verbose, holdoff, longwait, nthreads, onoff_holdoff, onoff_interval, shutdown, stat_interval, stutter, use_cpus_read_lock, weight_resched, weight_single, weight_single_rpc, weight_single_wait, weight_many, weight_many_wait, weight_all, weight_all_wait);
 502 }
 503
 504 static void scf_cleanup_handler(void *unused)
 505 {
 506 }
 507
 508 static void scf_torture_cleanup(void)
 509 {
 510         int i;
 511
 512         if (torture_cleanup_begin())
 513                 return;
 514
 515         WRITE_ONCE(scfdone, true);
 516         if (nthreads && scf_stats_p)
 517                 for (i = 0; i < nthreads; i++)
 518                         torture_stop_kthread("scftorture_invoker", scf_stats_p[i].task);
 519         else
 520                 goto end;
 521         smp_call_function(scf_cleanup_handler, NULL, 0);
 522         torture_stop_kthread(scf_torture_stats, scf_torture_stats_task);
 523         scf_torture_stats_print();  // -After- the stats thread is stopped!
 524         kfree(scf_stats_p);  // -After- the last stats print has completed!
 525         scf_stats_p = NULL;
 526
 527         if (atomic_read(&n_errs) || atomic_read(&n_mb_in_errs) || atomic_read(&n_mb_out_errs))
 528                 scftorture_print_module_parms("End of test: FAILURE");
 529         else if (torture_onoff_failures())
 530                 scftorture_print_module_parms("End of test: LOCK_HOTPLUG");
 531         else
 532                 scftorture_print_module_parms("End of test: SUCCESS");
 533
 534 end:
 535         torture_cleanup_end();
 536 }
 537
 538 static int __init scf_torture_init(void)
 539 {
 540         long i;
 541         int firsterr = 0;
 542         unsigned long weight_resched1 = weight_resched;
 543         unsigned long weight_single1 = weight_single;
 544         unsigned long weight_single_rpc1 = weight_single_rpc;
 545         unsigned long weight_single_wait1 = weight_single_wait;
 546         unsigned long weight_many1 = weight_many;
 547         unsigned long weight_many_wait1 = weight_many_wait;
 548         unsigned long weight_all1 = weight_all;
 549         unsigned long weight_all_wait1 = weight_all_wait;
 550
 551         if (!torture_init_begin(SCFTORT_STRING, verbose))
 552                 return -EBUSY;
 553
 554         scftorture_print_module_parms("Start of test");
 555
 556         if (weight_resched <= 0 &&
 557             weight_single <= 0 && weight_single_rpc <= 0 && weight_single_wait <= 0 &&
 558             weight_many <= 0 && weight_many_wait <= 0 &&
 559             weight_all <= 0 && weight_all_wait <= 0) {
 560                 weight_resched1 = weight_resched == 0 ? 0 : 2 * nr_cpu_ids;
 561                 weight_single1 = weight_single == 0 ? 0 : 2 * nr_cpu_ids;
 562                 weight_single_rpc1 = weight_single_rpc == 0 ? 0 : 2 * nr_cpu_ids;
 563                 weight_single_wait1 = weight_single_wait == 0 ? 0 : 2 * nr_cpu_ids;
 564                 weight_many1 = weight_many == 0 ? 0 : 2;
 565                 weight_many_wait1 = weight_many_wait == 0 ? 0 : 2;
 566                 weight_all1 = weight_all == 0 ? 0 : 1;
 567                 weight_all_wait1 = weight_all_wait == 0 ? 0 : 1;
 568         } else {
 569                 if (weight_resched == -1)
 570                         weight_resched1 = 0;
 571                 if (weight_single == -1)
 572                         weight_single1 = 0;
 573                 if (weight_single_rpc == -1)
 574                         weight_single_rpc1 = 0;
 575                 if (weight_single_wait == -1)
 576                         weight_single_wait1 = 0;
 577                 if (weight_many == -1)
 578                         weight_many1 = 0;
 579                 if (weight_many_wait == -1)
 580                         weight_many_wait1 = 0;
 581                 if (weight_all == -1)
 582                         weight_all1 = 0;
 583                 if (weight_all_wait == -1)
 584                         weight_all_wait1 = 0;
 585         }
 586         if (weight_resched1 == 0 && weight_single1 == 0 && weight_single_rpc1 == 0 &&
 587             weight_single_wait1 == 0 && weight_many1 == 0 && weight_many_wait1 == 0 &&
 588             weight_all1 == 0 && weight_all_wait1 == 0) {
 589                 SCFTORTOUT_ERRSTRING("all zero weights makes no sense");
 590                 firsterr = -EINVAL;
 591                 goto unwind;
 592         }
 593         if (IS_BUILTIN(CONFIG_SCF_TORTURE_TEST))
 594                 scf_sel_add(weight_resched1, SCF_PRIM_RESCHED, false);
 595         else if (weight_resched1)
 596                 SCFTORTOUT_ERRSTRING("built as module, weight_resched ignored");
 597         scf_sel_add(weight_single1, SCF_PRIM_SINGLE, false);
 598         scf_sel_add(weight_single_rpc1, SCF_PRIM_SINGLE_RPC, true);
 599         scf_sel_add(weight_single_wait1, SCF_PRIM_SINGLE, true);
 600         scf_sel_add(weight_many1, SCF_PRIM_MANY, false);
 601         scf_sel_add(weight_many_wait1, SCF_PRIM_MANY, true);
 602         scf_sel_add(weight_all1, SCF_PRIM_ALL, false);
 603         scf_sel_add(weight_all_wait1, SCF_PRIM_ALL, true);
 604         scf_sel_dump();
 605
 606         if (onoff_interval > 0) {
 607                 firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval, NULL);
 608                 if (torture_init_error(firsterr))
 609                         goto unwind;
 610         }
 611         if (shutdown_secs > 0) {
 612                 firsterr = torture_shutdown_init(shutdown_secs, scf_torture_cleanup);
 613                 if (torture_init_error(firsterr))
 614                         goto unwind;
 615         }
 616         if (stutter > 0) {
 617                 firsterr = torture_stutter_init(stutter, stutter);
 618                 if (torture_init_error(firsterr))
 619                         goto unwind;
 620         }
 621
 622         // Worker tasks invoking smp_call_function().
 623         if (nthreads < 0)
 624                 nthreads = num_online_cpus();
 625         scf_stats_p = kcalloc(nthreads, sizeof(scf_stats_p[0]), GFP_KERNEL);
 626         if (!scf_stats_p) {
 627                 SCFTORTOUT_ERRSTRING("out of memory");
 628                 firsterr = -ENOMEM;
 629                 goto unwind;
 630         }
 631
 632         VERBOSE_SCFTORTOUT("Starting %d smp_call_function() threads", nthreads);
 633
 634         atomic_set(&n_started, nthreads);
 635         for (i = 0; i < nthreads; i++) {
 636                 scf_stats_p[i].cpu = i;
 637                 firsterr = torture_create_kthread(scftorture_invoker, (void *)&scf_stats_p[i],
 638                                                   scf_stats_p[i].task);
 639                 if (torture_init_error(firsterr))
 640                         goto unwind;
 641         }
 642         if (stat_interval > 0) {
 643                 firsterr = torture_create_kthread(scf_torture_stats, NULL, scf_torture_stats_task);
 644                 if (torture_init_error(firsterr))
 645                         goto unwind;
 646         }
 647
 648         torture_init_end();
 649         return 0;
 650
 651 unwind:
 652         torture_init_end();
 653         scf_torture_cleanup();
 654         if (shutdown_secs) {
 655                 WARN_ON(!IS_MODULE(CONFIG_SCF_TORTURE_TEST));
 656                 kernel_power_off();
 657         }
 658         return firsterr;
 659 }
 660
 661 module_init(scf_torture_init);
 662 module_exit(scf_torture_cleanup);