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