kernel/rcutorture.c

   1 /*
   2  * Read-Copy Update module-based torture test facility
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  17  *
  18  * Copyright (C) IBM Corporation, 2005, 2006
  19  *
  20  * Authors: Paul E. McKenney <paulmck@us.ibm.com>
  21  *        Josh Triplett <josh@freedesktop.org>
  22  *
  23  * See also:  Documentation/RCU/torture.txt
  24  */
  25 #include <linux/types.h>
  26 #include <linux/kernel.h>
  27 #include <linux/init.h>
  28 #include <linux/module.h>
  29 #include <linux/kthread.h>
  30 #include <linux/err.h>
  31 #include <linux/spinlock.h>
  32 #include <linux/smp.h>
  33 #include <linux/rcupdate.h>
  34 #include <linux/interrupt.h>
  35 #include <linux/sched.h>
  36 #include <linux/atomic.h>
  37 #include <linux/bitops.h>
  38 #include <linux/completion.h>
  39 #include <linux/moduleparam.h>
  40 #include <linux/percpu.h>
  41 #include <linux/notifier.h>
  42 #include <linux/reboot.h>
  43 #include <linux/freezer.h>
  44 #include <linux/cpu.h>
  45 #include <linux/delay.h>
  46 #include <linux/stat.h>
  47 #include <linux/srcu.h>
  48 #include <linux/slab.h>
  49 #include <asm/byteorder.h>
  50
  51 MODULE_LICENSE("GPL");
  52 MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and "
  53               "Josh Triplett <josh@freedesktop.org>");
  54
  55 static int nreaders = -1;       /* # reader threads, defaults to 2*ncpus */
  56 static int nfakewriters = 4;    /* # fake writer threads */
  57 static int stat_interval;       /* Interval between stats, in seconds. */
  58                                 /*  Defaults to "only at end of test". */
  59 static int verbose;             /* Print more debug info. */
  60 static int test_no_idle_hz;     /* Test RCU's support for tickless idle CPUs. */
  61 static int shuffle_interval = 3; /* Interval between shuffles (in sec)*/
  62 static int stutter = 5;         /* Start/stop testing interval (in sec) */
  63 static int irqreader = 1;       /* RCU readers from irq (timers). */
  64 static int fqs_duration;        /* Duration of bursts (us), 0 to disable. */
  65 static int fqs_holdoff;         /* Hold time within burst (us). */
  66 static int fqs_stutter = 3;     /* Wait time between bursts (s). */
  67 static int onoff_interval;      /* Wait time between CPU hotplugs, 0=disable. */
  68 static int shutdown_secs;       /* Shutdown time (s).  <=0 for no shutdown. */
  69 static int test_boost = 1;      /* Test RCU prio boost: 0=no, 1=maybe, 2=yes. */
  70 static int test_boost_interval = 7; /* Interval between boost tests, seconds. */
  71 static int test_boost_duration = 4; /* Duration of each boost test, seconds. */
  72 static char *torture_type = "rcu"; /* What RCU implementation to torture. */
  73
  74 module_param(nreaders, int, 0444);
  75 MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
  76 module_param(nfakewriters, int, 0444);
  77 MODULE_PARM_DESC(nfakewriters, "Number of RCU fake writer threads");
  78 module_param(stat_interval, int, 0644);
  79 MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
  80 module_param(verbose, bool, 0444);
  81 MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
  82 module_param(test_no_idle_hz, bool, 0444);
  83 MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
  84 module_param(shuffle_interval, int, 0444);
  85 MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
  86 module_param(stutter, int, 0444);
  87 MODULE_PARM_DESC(stutter, "Number of seconds to run/halt test");
  88 module_param(irqreader, int, 0444);
  89 MODULE_PARM_DESC(irqreader, "Allow RCU readers from irq handlers");
  90 module_param(fqs_duration, int, 0444);
  91 MODULE_PARM_DESC(fqs_duration, "Duration of fqs bursts (us)");
  92 module_param(fqs_holdoff, int, 0444);
  93 MODULE_PARM_DESC(fqs_holdoff, "Holdoff time within fqs bursts (us)");
  94 module_param(fqs_stutter, int, 0444);
  95 MODULE_PARM_DESC(fqs_stutter, "Wait time between fqs bursts (s)");
  96 module_param(onoff_interval, int, 0444);
  97 MODULE_PARM_DESC(onoff_interval, "Time between CPU hotplugs (s), 0=disable");
  98 module_param(shutdown_secs, int, 0444);
  99 MODULE_PARM_DESC(shutdown_secs, "Shutdown time (s), zero to disable.");
 100 module_param(test_boost, int, 0444);
 101 MODULE_PARM_DESC(test_boost, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
 102 module_param(test_boost_interval, int, 0444);
 103 MODULE_PARM_DESC(test_boost_interval, "Interval between boost tests, seconds.");
 104 module_param(test_boost_duration, int, 0444);
 105 MODULE_PARM_DESC(test_boost_duration, "Duration of each boost test, seconds.");
 106 module_param(torture_type, charp, 0444);
 107 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, srcu)");
 108
 109 #define TORTURE_FLAG "-torture:"
 110 #define PRINTK_STRING(s) \
 111         do { printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
 112 #define VERBOSE_PRINTK_STRING(s) \
 113         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
 114 #define VERBOSE_PRINTK_ERRSTRING(s) \
 115         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
 116
 117 static char printk_buf[4096];
 118
 119 static int nrealreaders;
 120 static struct task_struct *writer_task;
 121 static struct task_struct **fakewriter_tasks;
 122 static struct task_struct **reader_tasks;
 123 static struct task_struct *stats_task;
 124 static struct task_struct *shuffler_task;
 125 static struct task_struct *stutter_task;
 126 static struct task_struct *fqs_task;
 127 static struct task_struct *boost_tasks[NR_CPUS];
 128 static struct task_struct *shutdown_task;
 129 #ifdef CONFIG_HOTPLUG_CPU
 130 static struct task_struct *onoff_task;
 131 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
 132
 133 #define RCU_TORTURE_PIPE_LEN 10
 134
 135 struct rcu_torture {
 136         struct rcu_head rtort_rcu;
 137         int rtort_pipe_count;
 138         struct list_head rtort_free;
 139         int rtort_mbtest;
 140 };
 141
 142 static LIST_HEAD(rcu_torture_freelist);
 143 static struct rcu_torture __rcu *rcu_torture_current;
 144 static unsigned long rcu_torture_current_version;
 145 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 146 static DEFINE_SPINLOCK(rcu_torture_lock);
 147 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
 148         { 0 };
 149 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) =
 150         { 0 };
 151 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 152 static atomic_t n_rcu_torture_alloc;
 153 static atomic_t n_rcu_torture_alloc_fail;
 154 static atomic_t n_rcu_torture_free;
 155 static atomic_t n_rcu_torture_mberror;
 156 static atomic_t n_rcu_torture_error;
 157 static long n_rcu_torture_boost_ktrerror;
 158 static long n_rcu_torture_boost_rterror;
 159 static long n_rcu_torture_boost_failure;
 160 static long n_rcu_torture_boosts;
 161 static long n_rcu_torture_timers;
 162 static long n_offline_attempts;
 163 static long n_offline_successes;
 164 static long n_online_attempts;
 165 static long n_online_successes;
 166 static struct list_head rcu_torture_removed;
 167 static cpumask_var_t shuffle_tmp_mask;
 168
 169 static int stutter_pause_test;
 170
 171 #if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
 172 #define RCUTORTURE_RUNNABLE_INIT 1
 173 #else
 174 #define RCUTORTURE_RUNNABLE_INIT 0
 175 #endif
 176 int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT;
 177 module_param(rcutorture_runnable, int, 0444);
 178 MODULE_PARM_DESC(rcutorture_runnable, "Start rcutorture at boot");
 179
 180 #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
 181 #define rcu_can_boost() 1
 182 #else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 183 #define rcu_can_boost() 0
 184 #endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 185
 186 static unsigned long shutdown_time;     /* jiffies to system shutdown. */
 187 static unsigned long boost_starttime;   /* jiffies of next boost test start. */
 188 DEFINE_MUTEX(boost_mutex);              /* protect setting boost_starttime */
 189                                         /*  and boost task create/destroy. */
 190
 191 /* Mediate rmmod and system shutdown.  Concurrent rmmod & shutdown illegal! */
 192
 193 #define FULLSTOP_DONTSTOP 0     /* Normal operation. */
 194 #define FULLSTOP_SHUTDOWN 1     /* System shutdown with rcutorture running. */
 195 #define FULLSTOP_RMMOD    2     /* Normal rmmod of rcutorture. */
 196 static int fullstop = FULLSTOP_RMMOD;
 197 /*
 198  * Protect fullstop transitions and spawning of kthreads.
 199  */
 200 static DEFINE_MUTEX(fullstop_mutex);
 201
 202 /* Forward reference. */
 203 static void rcu_torture_cleanup(void);
 204
 205 /*
 206  * Detect and respond to a system shutdown.
 207  */
 208 static int
 209 rcutorture_shutdown_notify(struct notifier_block *unused1,
 210                            unsigned long unused2, void *unused3)
 211 {
 212         mutex_lock(&fullstop_mutex);
 213         if (fullstop == FULLSTOP_DONTSTOP)
 214                 fullstop = FULLSTOP_SHUTDOWN;
 215         else
 216                 printk(KERN_WARNING /* but going down anyway, so... */
 217                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
 218         mutex_unlock(&fullstop_mutex);
 219         return NOTIFY_DONE;
 220 }
 221
 222 /*
 223  * Absorb kthreads into a kernel function that won't return, so that
 224  * they won't ever access module text or data again.
 225  */
 226 static void rcutorture_shutdown_absorb(char *title)
 227 {
 228         if (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
 229                 printk(KERN_NOTICE
 230                        "rcutorture thread %s parking due to system shutdown\n",
 231                        title);
 232                 schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
 233         }
 234 }
 235
 236 /*
 237  * Allocate an element from the rcu_tortures pool.
 238  */
 239 static struct rcu_torture *
 240 rcu_torture_alloc(void)
 241 {
 242         struct list_head *p;
 243
 244         spin_lock_bh(&rcu_torture_lock);
 245         if (list_empty(&rcu_torture_freelist)) {
 246                 atomic_inc(&n_rcu_torture_alloc_fail);
 247                 spin_unlock_bh(&rcu_torture_lock);
 248                 return NULL;
 249         }
 250         atomic_inc(&n_rcu_torture_alloc);
 251         p = rcu_torture_freelist.next;
 252         list_del_init(p);
 253         spin_unlock_bh(&rcu_torture_lock);
 254         return container_of(p, struct rcu_torture, rtort_free);
 255 }
 256
 257 /*
 258  * Free an element to the rcu_tortures pool.
 259  */
 260 static void
 261 rcu_torture_free(struct rcu_torture *p)
 262 {
 263         atomic_inc(&n_rcu_torture_free);
 264         spin_lock_bh(&rcu_torture_lock);
 265         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 266         spin_unlock_bh(&rcu_torture_lock);
 267 }
 268
 269 struct rcu_random_state {
 270         unsigned long rrs_state;
 271         long rrs_count;
 272 };
 273
 274 #define RCU_RANDOM_MULT 39916801  /* prime */
 275 #define RCU_RANDOM_ADD  479001701 /* prime */
 276 #define RCU_RANDOM_REFRESH 10000
 277
 278 #define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
 279
 280 /*
 281  * Crude but fast random-number generator.  Uses a linear congruential
 282  * generator, with occasional help from cpu_clock().
 283  */
 284 static unsigned long
 285 rcu_random(struct rcu_random_state *rrsp)
 286 {
 287         if (--rrsp->rrs_count < 0) {
 288                 rrsp->rrs_state += (unsigned long)local_clock();
 289                 rrsp->rrs_count = RCU_RANDOM_REFRESH;
 290         }
 291         rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
 292         return swahw32(rrsp->rrs_state);
 293 }
 294
 295 static void
 296 rcu_stutter_wait(char *title)
 297 {
 298         while (stutter_pause_test || !rcutorture_runnable) {
 299                 if (rcutorture_runnable)
 300                         schedule_timeout_interruptible(1);
 301                 else
 302                         schedule_timeout_interruptible(round_jiffies_relative(HZ));
 303                 rcutorture_shutdown_absorb(title);
 304         }
 305 }
 306
 307 /*
 308  * Operations vector for selecting different types of tests.
 309  */
 310
 311 struct rcu_torture_ops {
 312         void (*init)(void);
 313         void (*cleanup)(void);
 314         int (*readlock)(void);
 315         void (*read_delay)(struct rcu_random_state *rrsp);
 316         void (*readunlock)(int idx);
 317         int (*completed)(void);
 318         void (*deferred_free)(struct rcu_torture *p);
 319         void (*sync)(void);
 320         void (*cb_barrier)(void);
 321         void (*fqs)(void);
 322         int (*stats)(char *page);
 323         int irq_capable;
 324         int can_boost;
 325         char *name;
 326 };
 327
 328 static struct rcu_torture_ops *cur_ops;
 329
 330 /*
 331  * Definitions for rcu torture testing.
 332  */
 333
 334 static int rcu_torture_read_lock(void) __acquires(RCU)
 335 {
 336         rcu_read_lock();
 337         return 0;
 338 }
 339
 340 static void rcu_read_delay(struct rcu_random_state *rrsp)
 341 {
 342         const unsigned long shortdelay_us = 200;
 343         const unsigned long longdelay_ms = 50;
 344
 345         /* We want a short delay sometimes to make a reader delay the grace
 346          * period, and we want a long delay occasionally to trigger
 347          * force_quiescent_state. */
 348
 349         if (!(rcu_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
 350                 mdelay(longdelay_ms);
 351         if (!(rcu_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
 352                 udelay(shortdelay_us);
 353 #ifdef CONFIG_PREEMPT
 354         if (!preempt_count() && !(rcu_random(rrsp) % (nrealreaders * 20000)))
 355                 preempt_schedule();  /* No QS if preempt_disable() in effect */
 356 #endif
 357 }
 358
 359 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 360 {
 361         rcu_read_unlock();
 362 }
 363
 364 static int rcu_torture_completed(void)
 365 {
 366         return rcu_batches_completed();
 367 }
 368
 369 static void
 370 rcu_torture_cb(struct rcu_head *p)
 371 {
 372         int i;
 373         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 374
 375         if (fullstop != FULLSTOP_DONTSTOP) {
 376                 /* Test is ending, just drop callbacks on the floor. */
 377                 /* The next initialization will pick up the pieces. */
 378                 return;
 379         }
 380         i = rp->rtort_pipe_count;
 381         if (i > RCU_TORTURE_PIPE_LEN)
 382                 i = RCU_TORTURE_PIPE_LEN;
 383         atomic_inc(&rcu_torture_wcount[i]);
 384         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 385                 rp->rtort_mbtest = 0;
 386                 rcu_torture_free(rp);
 387         } else
 388                 cur_ops->deferred_free(rp);
 389 }
 390
 391 static int rcu_no_completed(void)
 392 {
 393         return 0;
 394 }
 395
 396 static void rcu_torture_deferred_free(struct rcu_torture *p)
 397 {
 398         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 399 }
 400
 401 static struct rcu_torture_ops rcu_ops = {
 402         .init           = NULL,
 403         .cleanup        = NULL,
 404         .readlock       = rcu_torture_read_lock,
 405         .read_delay     = rcu_read_delay,
 406         .readunlock     = rcu_torture_read_unlock,
 407         .completed      = rcu_torture_completed,
 408         .deferred_free  = rcu_torture_deferred_free,
 409         .sync           = synchronize_rcu,
 410         .cb_barrier     = rcu_barrier,
 411         .fqs            = rcu_force_quiescent_state,
 412         .stats          = NULL,
 413         .irq_capable    = 1,
 414         .can_boost      = rcu_can_boost(),
 415         .name           = "rcu"
 416 };
 417
 418 static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
 419 {
 420         int i;
 421         struct rcu_torture *rp;
 422         struct rcu_torture *rp1;
 423
 424         cur_ops->sync();
 425         list_add(&p->rtort_free, &rcu_torture_removed);
 426         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 427                 i = rp->rtort_pipe_count;
 428                 if (i > RCU_TORTURE_PIPE_LEN)
 429                         i = RCU_TORTURE_PIPE_LEN;
 430                 atomic_inc(&rcu_torture_wcount[i]);
 431                 if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 432                         rp->rtort_mbtest = 0;
 433                         list_del(&rp->rtort_free);
 434                         rcu_torture_free(rp);
 435                 }
 436         }
 437 }
 438
 439 static void rcu_sync_torture_init(void)
 440 {
 441         INIT_LIST_HEAD(&rcu_torture_removed);
 442 }
 443
 444 static struct rcu_torture_ops rcu_sync_ops = {
 445         .init           = rcu_sync_torture_init,
 446         .cleanup        = NULL,
 447         .readlock       = rcu_torture_read_lock,
 448         .read_delay     = rcu_read_delay,
 449         .readunlock     = rcu_torture_read_unlock,
 450         .completed      = rcu_torture_completed,
 451         .deferred_free  = rcu_sync_torture_deferred_free,
 452         .sync           = synchronize_rcu,
 453         .cb_barrier     = NULL,
 454         .fqs            = rcu_force_quiescent_state,
 455         .stats          = NULL,
 456         .irq_capable    = 1,
 457         .can_boost      = rcu_can_boost(),
 458         .name           = "rcu_sync"
 459 };
 460
 461 static struct rcu_torture_ops rcu_expedited_ops = {
 462         .init           = rcu_sync_torture_init,
 463         .cleanup        = NULL,
 464         .readlock       = rcu_torture_read_lock,
 465         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 466         .readunlock     = rcu_torture_read_unlock,
 467         .completed      = rcu_no_completed,
 468         .deferred_free  = rcu_sync_torture_deferred_free,
 469         .sync           = synchronize_rcu_expedited,
 470         .cb_barrier     = NULL,
 471         .fqs            = rcu_force_quiescent_state,
 472         .stats          = NULL,
 473         .irq_capable    = 1,
 474         .can_boost      = rcu_can_boost(),
 475         .name           = "rcu_expedited"
 476 };
 477
 478 /*
 479  * Definitions for rcu_bh torture testing.
 480  */
 481
 482 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
 483 {
 484         rcu_read_lock_bh();
 485         return 0;
 486 }
 487
 488 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
 489 {
 490         rcu_read_unlock_bh();
 491 }
 492
 493 static int rcu_bh_torture_completed(void)
 494 {
 495         return rcu_batches_completed_bh();
 496 }
 497
 498 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 499 {
 500         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
 501 }
 502
 503 static struct rcu_torture_ops rcu_bh_ops = {
 504         .init           = NULL,
 505         .cleanup        = NULL,
 506         .readlock       = rcu_bh_torture_read_lock,
 507         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 508         .readunlock     = rcu_bh_torture_read_unlock,
 509         .completed      = rcu_bh_torture_completed,
 510         .deferred_free  = rcu_bh_torture_deferred_free,
 511         .sync           = synchronize_rcu_bh,
 512         .cb_barrier     = rcu_barrier_bh,
 513         .fqs            = rcu_bh_force_quiescent_state,
 514         .stats          = NULL,
 515         .irq_capable    = 1,
 516         .name           = "rcu_bh"
 517 };
 518
 519 static struct rcu_torture_ops rcu_bh_sync_ops = {
 520         .init           = rcu_sync_torture_init,
 521         .cleanup        = NULL,
 522         .readlock       = rcu_bh_torture_read_lock,
 523         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 524         .readunlock     = rcu_bh_torture_read_unlock,
 525         .completed      = rcu_bh_torture_completed,
 526         .deferred_free  = rcu_sync_torture_deferred_free,
 527         .sync           = synchronize_rcu_bh,
 528         .cb_barrier     = NULL,
 529         .fqs            = rcu_bh_force_quiescent_state,
 530         .stats          = NULL,
 531         .irq_capable    = 1,
 532         .name           = "rcu_bh_sync"
 533 };
 534
 535 static struct rcu_torture_ops rcu_bh_expedited_ops = {
 536         .init           = rcu_sync_torture_init,
 537         .cleanup        = NULL,
 538         .readlock       = rcu_bh_torture_read_lock,
 539         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 540         .readunlock     = rcu_bh_torture_read_unlock,
 541         .completed      = rcu_bh_torture_completed,
 542         .deferred_free  = rcu_sync_torture_deferred_free,
 543         .sync           = synchronize_rcu_bh_expedited,
 544         .cb_barrier     = NULL,
 545         .fqs            = rcu_bh_force_quiescent_state,
 546         .stats          = NULL,
 547         .irq_capable    = 1,
 548         .name           = "rcu_bh_expedited"
 549 };
 550
 551 /*
 552  * Definitions for srcu torture testing.
 553  */
 554
 555 static struct srcu_struct srcu_ctl;
 556
 557 static void srcu_torture_init(void)
 558 {
 559         init_srcu_struct(&srcu_ctl);
 560         rcu_sync_torture_init();
 561 }
 562
 563 static void srcu_torture_cleanup(void)
 564 {
 565         synchronize_srcu(&srcu_ctl);
 566         cleanup_srcu_struct(&srcu_ctl);
 567 }
 568
 569 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
 570 {
 571         return srcu_read_lock(&srcu_ctl);
 572 }
 573
 574 static void srcu_read_delay(struct rcu_random_state *rrsp)
 575 {
 576         long delay;
 577         const long uspertick = 1000000 / HZ;
 578         const long longdelay = 10;
 579
 580         /* We want there to be long-running readers, but not all the time. */
 581
 582         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
 583         if (!delay)
 584                 schedule_timeout_interruptible(longdelay);
 585         else
 586                 rcu_read_delay(rrsp);
 587 }
 588
 589 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
 590 {
 591         srcu_read_unlock(&srcu_ctl, idx);
 592 }
 593
 594 static int srcu_torture_completed(void)
 595 {
 596         return srcu_batches_completed(&srcu_ctl);
 597 }
 598
 599 static void srcu_torture_synchronize(void)
 600 {
 601         synchronize_srcu(&srcu_ctl);
 602 }
 603
 604 static int srcu_torture_stats(char *page)
 605 {
 606         int cnt = 0;
 607         int cpu;
 608         int idx = srcu_ctl.completed & 0x1;
 609
 610         cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
 611                        torture_type, TORTURE_FLAG, idx);
 612         for_each_possible_cpu(cpu) {
 613                 cnt += sprintf(&page[cnt], " %d(%d,%d)", cpu,
 614                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
 615                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
 616         }
 617         cnt += sprintf(&page[cnt], "\n");
 618         return cnt;
 619 }
 620
 621 static struct rcu_torture_ops srcu_ops = {
 622         .init           = srcu_torture_init,
 623         .cleanup        = srcu_torture_cleanup,
 624         .readlock       = srcu_torture_read_lock,
 625         .read_delay     = srcu_read_delay,
 626         .readunlock     = srcu_torture_read_unlock,
 627         .completed      = srcu_torture_completed,
 628         .deferred_free  = rcu_sync_torture_deferred_free,
 629         .sync           = srcu_torture_synchronize,
 630         .cb_barrier     = NULL,
 631         .stats          = srcu_torture_stats,
 632         .name           = "srcu"
 633 };
 634
 635 static void srcu_torture_synchronize_expedited(void)
 636 {
 637         synchronize_srcu_expedited(&srcu_ctl);
 638 }
 639
 640 static struct rcu_torture_ops srcu_expedited_ops = {
 641         .init           = srcu_torture_init,
 642         .cleanup        = srcu_torture_cleanup,
 643         .readlock       = srcu_torture_read_lock,
 644         .read_delay     = srcu_read_delay,
 645         .readunlock     = srcu_torture_read_unlock,
 646         .completed      = srcu_torture_completed,
 647         .deferred_free  = rcu_sync_torture_deferred_free,
 648         .sync           = srcu_torture_synchronize_expedited,
 649         .cb_barrier     = NULL,
 650         .stats          = srcu_torture_stats,
 651         .name           = "srcu_expedited"
 652 };
 653
 654 /*
 655  * Definitions for sched torture testing.
 656  */
 657
 658 static int sched_torture_read_lock(void)
 659 {
 660         preempt_disable();
 661         return 0;
 662 }
 663
 664 static void sched_torture_read_unlock(int idx)
 665 {
 666         preempt_enable();
 667 }
 668
 669 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
 670 {
 671         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
 672 }
 673
 674 static struct rcu_torture_ops sched_ops = {
 675         .init           = rcu_sync_torture_init,
 676         .cleanup        = NULL,
 677         .readlock       = sched_torture_read_lock,
 678         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 679         .readunlock     = sched_torture_read_unlock,
 680         .completed      = rcu_no_completed,
 681         .deferred_free  = rcu_sched_torture_deferred_free,
 682         .sync           = synchronize_sched,
 683         .cb_barrier     = rcu_barrier_sched,
 684         .fqs            = rcu_sched_force_quiescent_state,
 685         .stats          = NULL,
 686         .irq_capable    = 1,
 687         .name           = "sched"
 688 };
 689
 690 static struct rcu_torture_ops sched_sync_ops = {
 691         .init           = rcu_sync_torture_init,
 692         .cleanup        = NULL,
 693         .readlock       = sched_torture_read_lock,
 694         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 695         .readunlock     = sched_torture_read_unlock,
 696         .completed      = rcu_no_completed,
 697         .deferred_free  = rcu_sync_torture_deferred_free,
 698         .sync           = synchronize_sched,
 699         .cb_barrier     = NULL,
 700         .fqs            = rcu_sched_force_quiescent_state,
 701         .stats          = NULL,
 702         .name           = "sched_sync"
 703 };
 704
 705 static struct rcu_torture_ops sched_expedited_ops = {
 706         .init           = rcu_sync_torture_init,
 707         .cleanup        = NULL,
 708         .readlock       = sched_torture_read_lock,
 709         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 710         .readunlock     = sched_torture_read_unlock,
 711         .completed      = rcu_no_completed,
 712         .deferred_free  = rcu_sync_torture_deferred_free,
 713         .sync           = synchronize_sched_expedited,
 714         .cb_barrier     = NULL,
 715         .fqs            = rcu_sched_force_quiescent_state,
 716         .stats          = NULL,
 717         .irq_capable    = 1,
 718         .name           = "sched_expedited"
 719 };
 720
 721 /*
 722  * RCU torture priority-boost testing.  Runs one real-time thread per
 723  * CPU for moderate bursts, repeatedly registering RCU callbacks and
 724  * spinning waiting for them to be invoked.  If a given callback takes
 725  * too long to be invoked, we assume that priority inversion has occurred.
 726  */
 727
 728 struct rcu_boost_inflight {
 729         struct rcu_head rcu;
 730         int inflight;
 731 };
 732
 733 static void rcu_torture_boost_cb(struct rcu_head *head)
 734 {
 735         struct rcu_boost_inflight *rbip =
 736                 container_of(head, struct rcu_boost_inflight, rcu);
 737
 738         smp_mb(); /* Ensure RCU-core accesses precede clearing ->inflight */
 739         rbip->inflight = 0;
 740 }
 741
 742 static int rcu_torture_boost(void *arg)
 743 {
 744         unsigned long call_rcu_time;
 745         unsigned long endtime;
 746         unsigned long oldstarttime;
 747         struct rcu_boost_inflight rbi = { .inflight = 0 };
 748         struct sched_param sp;
 749
 750         VERBOSE_PRINTK_STRING("rcu_torture_boost started");
 751
 752         /* Set real-time priority. */
 753         sp.sched_priority = 1;
 754         if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 755                 VERBOSE_PRINTK_STRING("rcu_torture_boost RT prio failed!");
 756                 n_rcu_torture_boost_rterror++;
 757         }
 758
 759         init_rcu_head_on_stack(&rbi.rcu);
 760         /* Each pass through the following loop does one boost-test cycle. */
 761         do {
 762                 /* Wait for the next test interval. */
 763                 oldstarttime = boost_starttime;
 764                 while (ULONG_CMP_LT(jiffies, oldstarttime)) {
 765                         schedule_timeout_uninterruptible(1);
 766                         rcu_stutter_wait("rcu_torture_boost");
 767                         if (kthread_should_stop() ||
 768                             fullstop != FULLSTOP_DONTSTOP)
 769                                 goto checkwait;
 770                 }
 771
 772                 /* Do one boost-test interval. */
 773                 endtime = oldstarttime + test_boost_duration * HZ;
 774                 call_rcu_time = jiffies;
 775                 while (ULONG_CMP_LT(jiffies, endtime)) {
 776                         /* If we don't have a callback in flight, post one. */
 777                         if (!rbi.inflight) {
 778                                 smp_mb(); /* RCU core before ->inflight = 1. */
 779                                 rbi.inflight = 1;
 780                                 call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 781                                 if (jiffies - call_rcu_time >
 782                                          test_boost_duration * HZ - HZ / 2) {
 783                                         VERBOSE_PRINTK_STRING("rcu_torture_boost boosting failed");
 784                                         n_rcu_torture_boost_failure++;
 785                                 }
 786                                 call_rcu_time = jiffies;
 787                         }
 788                         cond_resched();
 789                         rcu_stutter_wait("rcu_torture_boost");
 790                         if (kthread_should_stop() ||
 791                             fullstop != FULLSTOP_DONTSTOP)
 792                                 goto checkwait;
 793                 }
 794
 795                 /*
 796                  * Set the start time of the next test interval.
 797                  * Yes, this is vulnerable to long delays, but such
 798                  * delays simply cause a false negative for the next
 799                  * interval.  Besides, we are running at RT priority,
 800                  * so delays should be relatively rare.
 801                  */
 802                 while (oldstarttime == boost_starttime &&
 803                        !kthread_should_stop()) {
 804                         if (mutex_trylock(&boost_mutex)) {
 805                                 boost_starttime = jiffies +
 806                                                   test_boost_interval * HZ;
 807                                 n_rcu_torture_boosts++;
 808                                 mutex_unlock(&boost_mutex);
 809                                 break;
 810                         }
 811                         schedule_timeout_uninterruptible(1);
 812                 }
 813
 814                 /* Go do the stutter. */
 815 checkwait:      rcu_stutter_wait("rcu_torture_boost");
 816         } while (!kthread_should_stop() && fullstop  == FULLSTOP_DONTSTOP);
 817
 818         /* Clean up and exit. */
 819         VERBOSE_PRINTK_STRING("rcu_torture_boost task stopping");
 820         rcutorture_shutdown_absorb("rcu_torture_boost");
 821         while (!kthread_should_stop() || rbi.inflight)
 822                 schedule_timeout_uninterruptible(1);
 823         smp_mb(); /* order accesses to ->inflight before stack-frame death. */
 824         destroy_rcu_head_on_stack(&rbi.rcu);
 825         return 0;
 826 }
 827
 828 /*
 829  * RCU torture force-quiescent-state kthread.  Repeatedly induces
 830  * bursts of calls to force_quiescent_state(), increasing the probability
 831  * of occurrence of some important types of race conditions.
 832  */
 833 static int
 834 rcu_torture_fqs(void *arg)
 835 {
 836         unsigned long fqs_resume_time;
 837         int fqs_burst_remaining;
 838
 839         VERBOSE_PRINTK_STRING("rcu_torture_fqs task started");
 840         do {
 841                 fqs_resume_time = jiffies + fqs_stutter * HZ;
 842                 while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
 843                        !kthread_should_stop()) {
 844                         schedule_timeout_interruptible(1);
 845                 }
 846                 fqs_burst_remaining = fqs_duration;
 847                 while (fqs_burst_remaining > 0 &&
 848                        !kthread_should_stop()) {
 849                         cur_ops->fqs();
 850                         udelay(fqs_holdoff);
 851                         fqs_burst_remaining -= fqs_holdoff;
 852                 }
 853                 rcu_stutter_wait("rcu_torture_fqs");
 854         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 855         VERBOSE_PRINTK_STRING("rcu_torture_fqs task stopping");
 856         rcutorture_shutdown_absorb("rcu_torture_fqs");
 857         while (!kthread_should_stop())
 858                 schedule_timeout_uninterruptible(1);
 859         return 0;
 860 }
 861
 862 /*
 863  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 864  * for that pointed to by rcu_torture_current, freeing the old structure
 865  * after a series of grace periods (the "pipeline").
 866  */
 867 static int
 868 rcu_torture_writer(void *arg)
 869 {
 870         int i;
 871         long oldbatch = rcu_batches_completed();
 872         struct rcu_torture *rp;
 873         struct rcu_torture *old_rp;
 874         static DEFINE_RCU_RANDOM(rand);
 875
 876         VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
 877         set_user_nice(current, 19);
 878
 879         do {
 880                 schedule_timeout_uninterruptible(1);
 881                 rp = rcu_torture_alloc();
 882                 if (rp == NULL)
 883                         continue;
 884                 rp->rtort_pipe_count = 0;
 885                 udelay(rcu_random(&rand) & 0x3ff);
 886                 old_rp = rcu_dereference_check(rcu_torture_current,
 887                                                current == writer_task);
 888                 rp->rtort_mbtest = 1;
 889                 rcu_assign_pointer(rcu_torture_current, rp);
 890                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
 891                 if (old_rp) {
 892                         i = old_rp->rtort_pipe_count;
 893                         if (i > RCU_TORTURE_PIPE_LEN)
 894                                 i = RCU_TORTURE_PIPE_LEN;
 895                         atomic_inc(&rcu_torture_wcount[i]);
 896                         old_rp->rtort_pipe_count++;
 897                         cur_ops->deferred_free(old_rp);
 898                 }
 899                 rcutorture_record_progress(++rcu_torture_current_version);
 900                 oldbatch = cur_ops->completed();
 901                 rcu_stutter_wait("rcu_torture_writer");
 902         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 903         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
 904         rcutorture_shutdown_absorb("rcu_torture_writer");
 905         while (!kthread_should_stop())
 906                 schedule_timeout_uninterruptible(1);
 907         return 0;
 908 }
 909
 910 /*
 911  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
 912  * delay between calls.
 913  */
 914 static int
 915 rcu_torture_fakewriter(void *arg)
 916 {
 917         DEFINE_RCU_RANDOM(rand);
 918
 919         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
 920         set_user_nice(current, 19);
 921
 922         do {
 923                 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
 924                 udelay(rcu_random(&rand) & 0x3ff);
 925                 cur_ops->sync();
 926                 rcu_stutter_wait("rcu_torture_fakewriter");
 927         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 928
 929         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
 930         rcutorture_shutdown_absorb("rcu_torture_fakewriter");
 931         while (!kthread_should_stop())
 932                 schedule_timeout_uninterruptible(1);
 933         return 0;
 934 }
 935
 936 void rcutorture_trace_dump(void)
 937 {
 938         static atomic_t beenhere = ATOMIC_INIT(0);
 939
 940         if (atomic_read(&beenhere))
 941                 return;
 942         if (atomic_xchg(&beenhere, 1) != 0)
 943                 return;
 944         do_trace_rcu_torture_read(cur_ops->name, (struct rcu_head *)~0UL);
 945         ftrace_dump(DUMP_ALL);
 946 }
 947
 948 /*
 949  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
 950  * incrementing the corresponding element of the pipeline array.  The
 951  * counter in the element should never be greater than 1, otherwise, the
 952  * RCU implementation is broken.
 953  */
 954 static void rcu_torture_timer(unsigned long unused)
 955 {
 956         int idx;
 957         int completed;
 958         static DEFINE_RCU_RANDOM(rand);
 959         static DEFINE_SPINLOCK(rand_lock);
 960         struct rcu_torture *p;
 961         int pipe_count;
 962
 963         idx = cur_ops->readlock();
 964         completed = cur_ops->completed();
 965         p = rcu_dereference_check(rcu_torture_current,
 966                                   rcu_read_lock_bh_held() ||
 967                                   rcu_read_lock_sched_held() ||
 968                                   srcu_read_lock_held(&srcu_ctl));
 969         do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu);
 970         if (p == NULL) {
 971                 /* Leave because rcu_torture_writer is not yet underway */
 972                 cur_ops->readunlock(idx);
 973                 return;
 974         }
 975         if (p->rtort_mbtest == 0)
 976                 atomic_inc(&n_rcu_torture_mberror);
 977         spin_lock(&rand_lock);
 978         cur_ops->read_delay(&rand);
 979         n_rcu_torture_timers++;
 980         spin_unlock(&rand_lock);
 981         preempt_disable();
 982         pipe_count = p->rtort_pipe_count;
 983         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
 984                 /* Should not happen, but... */
 985                 pipe_count = RCU_TORTURE_PIPE_LEN;
 986         }
 987         if (pipe_count > 1)
 988                 rcutorture_trace_dump();
 989         __this_cpu_inc(rcu_torture_count[pipe_count]);
 990         completed = cur_ops->completed() - completed;
 991         if (completed > RCU_TORTURE_PIPE_LEN) {
 992                 /* Should not happen, but... */
 993                 completed = RCU_TORTURE_PIPE_LEN;
 994         }
 995         __this_cpu_inc(rcu_torture_batch[completed]);
 996         preempt_enable();
 997         cur_ops->readunlock(idx);
 998 }
 999
1000 /*
1001  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
1002  * incrementing the corresponding element of the pipeline array.  The
1003  * counter in the element should never be greater than 1, otherwise, the
1004  * RCU implementation is broken.
1005  */
1006 static int
1007 rcu_torture_reader(void *arg)
1008 {
1009         int completed;
1010         int idx;
1011         DEFINE_RCU_RANDOM(rand);
1012         struct rcu_torture *p;
1013         int pipe_count;
1014         struct timer_list t;
1015
1016         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
1017         set_user_nice(current, 19);
1018         if (irqreader && cur_ops->irq_capable)
1019                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
1020
1021         do {
1022                 if (irqreader && cur_ops->irq_capable) {
1023                         if (!timer_pending(&t))
1024                                 mod_timer(&t, jiffies + 1);
1025                 }
1026                 idx = cur_ops->readlock();
1027                 completed = cur_ops->completed();
1028                 p = rcu_dereference_check(rcu_torture_current,
1029                                           rcu_read_lock_bh_held() ||
1030                                           rcu_read_lock_sched_held() ||
1031                                           srcu_read_lock_held(&srcu_ctl));
1032                 do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu);
1033                 if (p == NULL) {
1034                         /* Wait for rcu_torture_writer to get underway */
1035                         cur_ops->readunlock(idx);
1036                         schedule_timeout_interruptible(HZ);
1037                         continue;
1038                 }
1039                 if (p->rtort_mbtest == 0)
1040                         atomic_inc(&n_rcu_torture_mberror);
1041                 cur_ops->read_delay(&rand);
1042                 preempt_disable();
1043                 pipe_count = p->rtort_pipe_count;
1044                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1045                         /* Should not happen, but... */
1046                         pipe_count = RCU_TORTURE_PIPE_LEN;
1047                 }
1048                 if (pipe_count > 1)
1049                         rcutorture_trace_dump();
1050                 __this_cpu_inc(rcu_torture_count[pipe_count]);
1051                 completed = cur_ops->completed() - completed;
1052                 if (completed > RCU_TORTURE_PIPE_LEN) {
1053                         /* Should not happen, but... */
1054                         completed = RCU_TORTURE_PIPE_LEN;
1055                 }
1056                 __this_cpu_inc(rcu_torture_batch[completed]);
1057                 preempt_enable();
1058                 cur_ops->readunlock(idx);
1059                 schedule();
1060                 rcu_stutter_wait("rcu_torture_reader");
1061         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1062         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
1063         rcutorture_shutdown_absorb("rcu_torture_reader");
1064         if (irqreader && cur_ops->irq_capable)
1065                 del_timer_sync(&t);
1066         while (!kthread_should_stop())
1067                 schedule_timeout_uninterruptible(1);
1068         return 0;
1069 }
1070
1071 /*
1072  * Create an RCU-torture statistics message in the specified buffer.
1073  */
1074 static int
1075 rcu_torture_printk(char *page)
1076 {
1077         int cnt = 0;
1078         int cpu;
1079         int i;
1080         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1081         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1082
1083         for_each_possible_cpu(cpu) {
1084                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1085                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1086                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1087                 }
1088         }
1089         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1090                 if (pipesummary[i] != 0)
1091                         break;
1092         }
1093         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
1094         cnt += sprintf(&page[cnt],
1095                        "rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d "
1096                        "rtmbe: %d rtbke: %ld rtbre: %ld "
1097                        "rtbf: %ld rtb: %ld nt: %ld "
1098                        "onoff: %ld/%ld:%ld/%ld",
1099                        rcu_torture_current,
1100                        rcu_torture_current_version,
1101                        list_empty(&rcu_torture_freelist),
1102                        atomic_read(&n_rcu_torture_alloc),
1103                        atomic_read(&n_rcu_torture_alloc_fail),
1104                        atomic_read(&n_rcu_torture_free),
1105                        atomic_read(&n_rcu_torture_mberror),
1106                        n_rcu_torture_boost_ktrerror,
1107                        n_rcu_torture_boost_rterror,
1108                        n_rcu_torture_boost_failure,
1109                        n_rcu_torture_boosts,
1110                        n_rcu_torture_timers,
1111                        n_online_successes,
1112                        n_online_attempts,
1113                        n_offline_successes,
1114                        n_offline_attempts);
1115         if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1116             n_rcu_torture_boost_ktrerror != 0 ||
1117             n_rcu_torture_boost_rterror != 0 ||
1118             n_rcu_torture_boost_failure != 0)
1119                 cnt += sprintf(&page[cnt], " !!!");
1120         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1121         if (i > 1) {
1122                 cnt += sprintf(&page[cnt], "!!! ");
1123                 atomic_inc(&n_rcu_torture_error);
1124                 WARN_ON_ONCE(1);
1125         }
1126         cnt += sprintf(&page[cnt], "Reader Pipe: ");
1127         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1128                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
1129         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1130         cnt += sprintf(&page[cnt], "Reader Batch: ");
1131         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1132                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
1133         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1134         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
1135         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1136                 cnt += sprintf(&page[cnt], " %d",
1137                                atomic_read(&rcu_torture_wcount[i]));
1138         }
1139         cnt += sprintf(&page[cnt], "\n");
1140         if (cur_ops->stats)
1141                 cnt += cur_ops->stats(&page[cnt]);
1142         return cnt;
1143 }
1144
1145 /*
1146  * Print torture statistics.  Caller must ensure that there is only
1147  * one call to this function at a given time!!!  This is normally
1148  * accomplished by relying on the module system to only have one copy
1149  * of the module loaded, and then by giving the rcu_torture_stats
1150  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1151  * thread is not running).
1152  */
1153 static void
1154 rcu_torture_stats_print(void)
1155 {
1156         int cnt;
1157
1158         cnt = rcu_torture_printk(printk_buf);
1159         printk(KERN_ALERT "%s", printk_buf);
1160 }
1161
1162 /*
1163  * Periodically prints torture statistics, if periodic statistics printing
1164  * was specified via the stat_interval module parameter.
1165  *
1166  * No need to worry about fullstop here, since this one doesn't reference
1167  * volatile state or register callbacks.
1168  */
1169 static int
1170 rcu_torture_stats(void *arg)
1171 {
1172         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
1173         do {
1174                 schedule_timeout_interruptible(stat_interval * HZ);
1175                 rcu_torture_stats_print();
1176                 rcutorture_shutdown_absorb("rcu_torture_stats");
1177         } while (!kthread_should_stop());
1178         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
1179         return 0;
1180 }
1181
1182 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
1183
1184 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
1185  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
1186  */
1187 static void rcu_torture_shuffle_tasks(void)
1188 {
1189         int i;
1190
1191         cpumask_setall(shuffle_tmp_mask);
1192         get_online_cpus();
1193
1194         /* No point in shuffling if there is only one online CPU (ex: UP) */
1195         if (num_online_cpus() == 1) {
1196                 put_online_cpus();
1197                 return;
1198         }
1199
1200         if (rcu_idle_cpu != -1)
1201                 cpumask_clear_cpu(rcu_idle_cpu, shuffle_tmp_mask);
1202
1203         set_cpus_allowed_ptr(current, shuffle_tmp_mask);
1204
1205         if (reader_tasks) {
1206                 for (i = 0; i < nrealreaders; i++)
1207                         if (reader_tasks[i])
1208                                 set_cpus_allowed_ptr(reader_tasks[i],
1209                                                      shuffle_tmp_mask);
1210         }
1211
1212         if (fakewriter_tasks) {
1213                 for (i = 0; i < nfakewriters; i++)
1214                         if (fakewriter_tasks[i])
1215                                 set_cpus_allowed_ptr(fakewriter_tasks[i],
1216                                                      shuffle_tmp_mask);
1217         }
1218
1219         if (writer_task)
1220                 set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
1221
1222         if (stats_task)
1223                 set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
1224
1225         if (rcu_idle_cpu == -1)
1226                 rcu_idle_cpu = num_online_cpus() - 1;
1227         else
1228                 rcu_idle_cpu--;
1229
1230         put_online_cpus();
1231 }
1232
1233 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
1234  * system to become idle at a time and cut off its timer ticks. This is meant
1235  * to test the support for such tickless idle CPU in RCU.
1236  */
1237 static int
1238 rcu_torture_shuffle(void *arg)
1239 {
1240         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
1241         do {
1242                 schedule_timeout_interruptible(shuffle_interval * HZ);
1243                 rcu_torture_shuffle_tasks();
1244                 rcutorture_shutdown_absorb("rcu_torture_shuffle");
1245         } while (!kthread_should_stop());
1246         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
1247         return 0;
1248 }
1249
1250 /* Cause the rcutorture test to "stutter", starting and stopping all
1251  * threads periodically.
1252  */
1253 static int
1254 rcu_torture_stutter(void *arg)
1255 {
1256         VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
1257         do {
1258                 schedule_timeout_interruptible(stutter * HZ);
1259                 stutter_pause_test = 1;
1260                 if (!kthread_should_stop())
1261                         schedule_timeout_interruptible(stutter * HZ);
1262                 stutter_pause_test = 0;
1263                 rcutorture_shutdown_absorb("rcu_torture_stutter");
1264         } while (!kthread_should_stop());
1265         VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
1266         return 0;
1267 }
1268
1269 static inline void
1270 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, char *tag)
1271 {
1272         printk(KERN_ALERT "%s" TORTURE_FLAG
1273                 "--- %s: nreaders=%d nfakewriters=%d "
1274                 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1275                 "shuffle_interval=%d stutter=%d irqreader=%d "
1276                 "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1277                 "test_boost=%d/%d test_boost_interval=%d "
1278                 "test_boost_duration=%d shutdown_secs=%d "
1279                 "onoff_interval=%d\n",
1280                 torture_type, tag, nrealreaders, nfakewriters,
1281                 stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1282                 stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1283                 test_boost, cur_ops->can_boost,
1284                 test_boost_interval, test_boost_duration, shutdown_secs,
1285                 onoff_interval);
1286 }
1287
1288 static struct notifier_block rcutorture_shutdown_nb = {
1289         .notifier_call = rcutorture_shutdown_notify,
1290 };
1291
1292 static void rcutorture_booster_cleanup(int cpu)
1293 {
1294         struct task_struct *t;
1295
1296         if (boost_tasks[cpu] == NULL)
1297                 return;
1298         mutex_lock(&boost_mutex);
1299         VERBOSE_PRINTK_STRING("Stopping rcu_torture_boost task");
1300         t = boost_tasks[cpu];
1301         boost_tasks[cpu] = NULL;
1302         mutex_unlock(&boost_mutex);
1303
1304         /* This must be outside of the mutex, otherwise deadlock! */
1305         kthread_stop(t);
1306 }
1307
1308 static int rcutorture_booster_init(int cpu)
1309 {
1310         int retval;
1311
1312         if (boost_tasks[cpu] != NULL)
1313                 return 0;  /* Already created, nothing more to do. */
1314
1315         /* Don't allow time recalculation while creating a new task. */
1316         mutex_lock(&boost_mutex);
1317         VERBOSE_PRINTK_STRING("Creating rcu_torture_boost task");
1318         boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1319                                                   cpu_to_node(cpu),
1320                                                   "rcu_torture_boost");
1321         if (IS_ERR(boost_tasks[cpu])) {
1322                 retval = PTR_ERR(boost_tasks[cpu]);
1323                 VERBOSE_PRINTK_STRING("rcu_torture_boost task create failed");
1324                 n_rcu_torture_boost_ktrerror++;
1325                 boost_tasks[cpu] = NULL;
1326                 mutex_unlock(&boost_mutex);
1327                 return retval;
1328         }
1329         kthread_bind(boost_tasks[cpu], cpu);
1330         wake_up_process(boost_tasks[cpu]);
1331         mutex_unlock(&boost_mutex);
1332         return 0;
1333 }
1334
1335 /*
1336  * Cause the rcutorture test to shutdown the system after the test has
1337  * run for the time specified by the shutdown_secs module parameter.
1338  */
1339 static int
1340 rcu_torture_shutdown(void *arg)
1341 {
1342         long delta;
1343         unsigned long jiffies_snap;
1344
1345         VERBOSE_PRINTK_STRING("rcu_torture_shutdown task started");
1346         jiffies_snap = ACCESS_ONCE(jiffies);
1347         while (ULONG_CMP_LT(jiffies_snap, shutdown_time) &&
1348                !kthread_should_stop()) {
1349                 delta = shutdown_time - jiffies_snap;
1350                 if (verbose)
1351                         printk(KERN_ALERT "%s" TORTURE_FLAG
1352                                "rcu_torture_shutdown task: %lu "
1353                                "jiffies remaining\n",
1354                                torture_type, delta);
1355                 schedule_timeout_interruptible(delta);
1356                 jiffies_snap = ACCESS_ONCE(jiffies);
1357         }
1358         if (kthread_should_stop()) {
1359                 VERBOSE_PRINTK_STRING("rcu_torture_shutdown task stopping");
1360                 return 0;
1361         }
1362
1363         /* OK, shut down the system. */
1364
1365         VERBOSE_PRINTK_STRING("rcu_torture_shutdown task shutting down system");
1366         shutdown_task = NULL;   /* Avoid self-kill deadlock. */
1367         rcu_torture_cleanup();  /* Get the success/failure message. */
1368         kernel_power_off();     /* Shut down the system. */
1369         return 0;
1370 }
1371
1372 #ifdef CONFIG_HOTPLUG_CPU
1373
1374 /*
1375  * Execute random CPU-hotplug operations at the interval specified
1376  * by the onoff_interval.
1377  */
1378 static int
1379 rcu_torture_onoff(void *arg)
1380 {
1381         int cpu;
1382         int maxcpu = -1;
1383         DEFINE_RCU_RANDOM(rand);
1384
1385         VERBOSE_PRINTK_STRING("rcu_torture_onoff task started");
1386         for_each_online_cpu(cpu)
1387                 maxcpu = cpu;
1388         WARN_ON(maxcpu < 0);
1389         while (!kthread_should_stop()) {
1390                 cpu = (rcu_random(&rand) >> 4) % (maxcpu + 1);
1391                 if (cpu_online(cpu) && cpu_is_hotpluggable(cpu)) {
1392                         if (verbose)
1393                                 printk(KERN_ALERT "%s" TORTURE_FLAG
1394                                        "rcu_torture_onoff task: offlining %d\n",
1395                                        torture_type, cpu);
1396                         n_offline_attempts++;
1397                         if (cpu_down(cpu) == 0) {
1398                                 if (verbose)
1399                                         printk(KERN_ALERT "%s" TORTURE_FLAG
1400                                                "rcu_torture_onoff task: "
1401                                                "offlined %d\n",
1402                                                torture_type, cpu);
1403                                 n_offline_successes++;
1404                         }
1405                 } else if (cpu_is_hotpluggable(cpu)) {
1406                         if (verbose)
1407                                 printk(KERN_ALERT "%s" TORTURE_FLAG
1408                                        "rcu_torture_onoff task: onlining %d\n",
1409                                        torture_type, cpu);
1410                         n_online_attempts++;
1411                         if (cpu_up(cpu) == 0) {
1412                                 if (verbose)
1413                                         printk(KERN_ALERT "%s" TORTURE_FLAG
1414                                                "rcu_torture_onoff task: "
1415                                                "onlined %d\n",
1416                                                torture_type, cpu);
1417                                 n_online_successes++;
1418                         }
1419                 }
1420                 schedule_timeout_interruptible(onoff_interval * HZ);
1421         }
1422         VERBOSE_PRINTK_STRING("rcu_torture_onoff task stopping");
1423         return 0;
1424 }
1425
1426 static int
1427 rcu_torture_onoff_init(void)
1428 {
1429         if (onoff_interval <= 0)
1430                 return 0;
1431         onoff_task = kthread_run(rcu_torture_onoff, NULL, "rcu_torture_onoff");
1432         if (IS_ERR(onoff_task)) {
1433                 onoff_task = NULL;
1434                 return PTR_ERR(onoff_task);
1435         }
1436         return 0;
1437 }
1438
1439 static void rcu_torture_onoff_cleanup(void)
1440 {
1441         if (onoff_task == NULL)
1442                 return;
1443         VERBOSE_PRINTK_STRING("Stopping rcu_torture_onoff task");
1444         kthread_stop(onoff_task);
1445 }
1446
1447 #else /* #ifdef CONFIG_HOTPLUG_CPU */
1448
1449 static void
1450 rcu_torture_onoff_init(void)
1451 {
1452 }
1453
1454 static void rcu_torture_onoff_cleanup(void)
1455 {
1456 }
1457
1458 #endif /* #else #ifdef CONFIG_HOTPLUG_CPU */
1459
1460 static int rcutorture_cpu_notify(struct notifier_block *self,
1461                                  unsigned long action, void *hcpu)
1462 {
1463         long cpu = (long)hcpu;
1464
1465         switch (action) {
1466         case CPU_ONLINE:
1467         case CPU_DOWN_FAILED:
1468                 (void)rcutorture_booster_init(cpu);
1469                 break;
1470         case CPU_DOWN_PREPARE:
1471                 rcutorture_booster_cleanup(cpu);
1472                 break;
1473         default:
1474                 break;
1475         }
1476         return NOTIFY_OK;
1477 }
1478
1479 static struct notifier_block rcutorture_cpu_nb = {
1480         .notifier_call = rcutorture_cpu_notify,
1481 };
1482
1483 static void
1484 rcu_torture_cleanup(void)
1485 {
1486         int i;
1487
1488         mutex_lock(&fullstop_mutex);
1489         rcutorture_record_test_transition();
1490         if (fullstop == FULLSTOP_SHUTDOWN) {
1491                 printk(KERN_WARNING /* but going down anyway, so... */
1492                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
1493                 mutex_unlock(&fullstop_mutex);
1494                 schedule_timeout_uninterruptible(10);
1495                 if (cur_ops->cb_barrier != NULL)
1496                         cur_ops->cb_barrier();
1497                 return;
1498         }
1499         fullstop = FULLSTOP_RMMOD;
1500         mutex_unlock(&fullstop_mutex);
1501         unregister_reboot_notifier(&rcutorture_shutdown_nb);
1502         if (stutter_task) {
1503                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
1504                 kthread_stop(stutter_task);
1505         }
1506         stutter_task = NULL;
1507         if (shuffler_task) {
1508                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
1509                 kthread_stop(shuffler_task);
1510                 free_cpumask_var(shuffle_tmp_mask);
1511         }
1512         shuffler_task = NULL;
1513
1514         if (writer_task) {
1515                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
1516                 kthread_stop(writer_task);
1517         }
1518         writer_task = NULL;
1519
1520         if (reader_tasks) {
1521                 for (i = 0; i < nrealreaders; i++) {
1522                         if (reader_tasks[i]) {
1523                                 VERBOSE_PRINTK_STRING(
1524                                         "Stopping rcu_torture_reader task");
1525                                 kthread_stop(reader_tasks[i]);
1526                         }
1527                         reader_tasks[i] = NULL;
1528                 }
1529                 kfree(reader_tasks);
1530                 reader_tasks = NULL;
1531         }
1532         rcu_torture_current = NULL;
1533
1534         if (fakewriter_tasks) {
1535                 for (i = 0; i < nfakewriters; i++) {
1536                         if (fakewriter_tasks[i]) {
1537                                 VERBOSE_PRINTK_STRING(
1538                                         "Stopping rcu_torture_fakewriter task");
1539                                 kthread_stop(fakewriter_tasks[i]);
1540                         }
1541                         fakewriter_tasks[i] = NULL;
1542                 }
1543                 kfree(fakewriter_tasks);
1544                 fakewriter_tasks = NULL;
1545         }
1546
1547         if (stats_task) {
1548                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
1549                 kthread_stop(stats_task);
1550         }
1551         stats_task = NULL;
1552
1553         if (fqs_task) {
1554                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_fqs task");
1555                 kthread_stop(fqs_task);
1556         }
1557         fqs_task = NULL;
1558         if ((test_boost == 1 && cur_ops->can_boost) ||
1559             test_boost == 2) {
1560                 unregister_cpu_notifier(&rcutorture_cpu_nb);
1561                 for_each_possible_cpu(i)
1562                         rcutorture_booster_cleanup(i);
1563         }
1564         if (shutdown_task != NULL) {
1565                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shutdown task");
1566                 kthread_stop(shutdown_task);
1567         }
1568         rcu_torture_onoff_cleanup();
1569
1570         /* Wait for all RCU callbacks to fire.  */
1571
1572         if (cur_ops->cb_barrier != NULL)
1573                 cur_ops->cb_barrier();
1574
1575         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1576
1577         if (cur_ops->cleanup)
1578                 cur_ops->cleanup();
1579         if (atomic_read(&n_rcu_torture_error))
1580                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1581         else
1582                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1583 }
1584
1585 static int __init
1586 rcu_torture_init(void)
1587 {
1588         int i;
1589         int cpu;
1590         int firsterr = 0;
1591         static struct rcu_torture_ops *torture_ops[] =
1592                 { &rcu_ops, &rcu_sync_ops, &rcu_expedited_ops,
1593                   &rcu_bh_ops, &rcu_bh_sync_ops, &rcu_bh_expedited_ops,
1594                   &srcu_ops, &srcu_expedited_ops,
1595                   &sched_ops, &sched_sync_ops, &sched_expedited_ops, };
1596
1597         mutex_lock(&fullstop_mutex);
1598
1599         /* Process args and tell the world that the torturer is on the job. */
1600         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1601                 cur_ops = torture_ops[i];
1602                 if (strcmp(torture_type, cur_ops->name) == 0)
1603                         break;
1604         }
1605         if (i == ARRAY_SIZE(torture_ops)) {
1606                 printk(KERN_ALERT "rcu-torture: invalid torture type: \"%s\"\n",
1607                        torture_type);
1608                 printk(KERN_ALERT "rcu-torture types:");
1609                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1610                         printk(KERN_ALERT " %s", torture_ops[i]->name);
1611                 printk(KERN_ALERT "\n");
1612                 mutex_unlock(&fullstop_mutex);
1613                 return -EINVAL;
1614         }
1615         if (cur_ops->fqs == NULL && fqs_duration != 0) {
1616                 printk(KERN_ALERT "rcu-torture: ->fqs NULL and non-zero "
1617                                   "fqs_duration, fqs disabled.\n");
1618                 fqs_duration = 0;
1619         }
1620         if (cur_ops->init)
1621                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1622
1623         if (nreaders >= 0)
1624                 nrealreaders = nreaders;
1625         else
1626                 nrealreaders = 2 * num_online_cpus();
1627         rcu_torture_print_module_parms(cur_ops, "Start of test");
1628         fullstop = FULLSTOP_DONTSTOP;
1629
1630         /* Set up the freelist. */
1631
1632         INIT_LIST_HEAD(&rcu_torture_freelist);
1633         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1634                 rcu_tortures[i].rtort_mbtest = 0;
1635                 list_add_tail(&rcu_tortures[i].rtort_free,
1636                               &rcu_torture_freelist);
1637         }
1638
1639         /* Initialize the statistics so that each run gets its own numbers. */
1640
1641         rcu_torture_current = NULL;
1642         rcu_torture_current_version = 0;
1643         atomic_set(&n_rcu_torture_alloc, 0);
1644         atomic_set(&n_rcu_torture_alloc_fail, 0);
1645         atomic_set(&n_rcu_torture_free, 0);
1646         atomic_set(&n_rcu_torture_mberror, 0);
1647         atomic_set(&n_rcu_torture_error, 0);
1648         n_rcu_torture_boost_ktrerror = 0;
1649         n_rcu_torture_boost_rterror = 0;
1650         n_rcu_torture_boost_failure = 0;
1651         n_rcu_torture_boosts = 0;
1652         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1653                 atomic_set(&rcu_torture_wcount[i], 0);
1654         for_each_possible_cpu(cpu) {
1655                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1656                         per_cpu(rcu_torture_count, cpu)[i] = 0;
1657                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
1658                 }
1659         }
1660
1661         /* Start up the kthreads. */
1662
1663         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
1664         writer_task = kthread_run(rcu_torture_writer, NULL,
1665                                   "rcu_torture_writer");
1666         if (IS_ERR(writer_task)) {
1667                 firsterr = PTR_ERR(writer_task);
1668                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
1669                 writer_task = NULL;
1670                 goto unwind;
1671         }
1672         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1673                                    GFP_KERNEL);
1674         if (fakewriter_tasks == NULL) {
1675                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1676                 firsterr = -ENOMEM;
1677                 goto unwind;
1678         }
1679         for (i = 0; i < nfakewriters; i++) {
1680                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
1681                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
1682                                                   "rcu_torture_fakewriter");
1683                 if (IS_ERR(fakewriter_tasks[i])) {
1684                         firsterr = PTR_ERR(fakewriter_tasks[i]);
1685                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
1686                         fakewriter_tasks[i] = NULL;
1687                         goto unwind;
1688                 }
1689         }
1690         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1691                                GFP_KERNEL);
1692         if (reader_tasks == NULL) {
1693                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1694                 firsterr = -ENOMEM;
1695                 goto unwind;
1696         }
1697         for (i = 0; i < nrealreaders; i++) {
1698                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
1699                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
1700                                               "rcu_torture_reader");
1701                 if (IS_ERR(reader_tasks[i])) {
1702                         firsterr = PTR_ERR(reader_tasks[i]);
1703                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
1704                         reader_tasks[i] = NULL;
1705                         goto unwind;
1706                 }
1707         }
1708         if (stat_interval > 0) {
1709                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
1710                 stats_task = kthread_run(rcu_torture_stats, NULL,
1711                                         "rcu_torture_stats");
1712                 if (IS_ERR(stats_task)) {
1713                         firsterr = PTR_ERR(stats_task);
1714                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
1715                         stats_task = NULL;
1716                         goto unwind;
1717                 }
1718         }
1719         if (test_no_idle_hz) {
1720                 rcu_idle_cpu = num_online_cpus() - 1;
1721
1722                 if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
1723                         firsterr = -ENOMEM;
1724                         VERBOSE_PRINTK_ERRSTRING("Failed to alloc mask");
1725                         goto unwind;
1726                 }
1727
1728                 /* Create the shuffler thread */
1729                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
1730                                           "rcu_torture_shuffle");
1731                 if (IS_ERR(shuffler_task)) {
1732                         free_cpumask_var(shuffle_tmp_mask);
1733                         firsterr = PTR_ERR(shuffler_task);
1734                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
1735                         shuffler_task = NULL;
1736                         goto unwind;
1737                 }
1738         }
1739         if (stutter < 0)
1740                 stutter = 0;
1741         if (stutter) {
1742                 /* Create the stutter thread */
1743                 stutter_task = kthread_run(rcu_torture_stutter, NULL,
1744                                           "rcu_torture_stutter");
1745                 if (IS_ERR(stutter_task)) {
1746                         firsterr = PTR_ERR(stutter_task);
1747                         VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
1748                         stutter_task = NULL;
1749                         goto unwind;
1750                 }
1751         }
1752         if (fqs_duration < 0)
1753                 fqs_duration = 0;
1754         if (fqs_duration) {
1755                 /* Create the stutter thread */
1756                 fqs_task = kthread_run(rcu_torture_fqs, NULL,
1757                                        "rcu_torture_fqs");
1758                 if (IS_ERR(fqs_task)) {
1759                         firsterr = PTR_ERR(fqs_task);
1760                         VERBOSE_PRINTK_ERRSTRING("Failed to create fqs");
1761                         fqs_task = NULL;
1762                         goto unwind;
1763                 }
1764         }
1765         if (test_boost_interval < 1)
1766                 test_boost_interval = 1;
1767         if (test_boost_duration < 2)
1768                 test_boost_duration = 2;
1769         if ((test_boost == 1 && cur_ops->can_boost) ||
1770             test_boost == 2) {
1771                 int retval;
1772
1773                 boost_starttime = jiffies + test_boost_interval * HZ;
1774                 register_cpu_notifier(&rcutorture_cpu_nb);
1775                 for_each_possible_cpu(i) {
1776                         if (cpu_is_offline(i))
1777                                 continue;  /* Heuristic: CPU can go offline. */
1778                         retval = rcutorture_booster_init(i);
1779                         if (retval < 0) {
1780                                 firsterr = retval;
1781                                 goto unwind;
1782                         }
1783                 }
1784         }
1785         if (shutdown_secs > 0) {
1786                 shutdown_time = jiffies + shutdown_secs * HZ;
1787                 shutdown_task = kthread_run(rcu_torture_shutdown, NULL,
1788                                             "rcu_torture_shutdown");
1789                 if (IS_ERR(shutdown_task)) {
1790                         firsterr = PTR_ERR(shutdown_task);
1791                         VERBOSE_PRINTK_ERRSTRING("Failed to create shutdown");
1792                         shutdown_task = NULL;
1793                         goto unwind;
1794                 }
1795         }
1796         rcu_torture_onoff_init();
1797         register_reboot_notifier(&rcutorture_shutdown_nb);
1798         rcutorture_record_test_transition();
1799         mutex_unlock(&fullstop_mutex);
1800         return 0;
1801
1802 unwind:
1803         mutex_unlock(&fullstop_mutex);
1804         rcu_torture_cleanup();
1805         return firsterr;
1806 }
1807
1808 module_init(rcu_torture_init);
1809 module_exit(rcu_torture_cleanup);