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