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 bool verbose;            /* Print more debug info. */
  60 static bool 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 int srcu_torture_read_lock_raw(void) __acquires(&srcu_ctl)
 636 {
 637         return srcu_read_lock_raw(&srcu_ctl);
 638 }
 639
 640 static void srcu_torture_read_unlock_raw(int idx) __releases(&srcu_ctl)
 641 {
 642         srcu_read_unlock_raw(&srcu_ctl, idx);
 643 }
 644
 645 static struct rcu_torture_ops srcu_raw_ops = {
 646         .init           = srcu_torture_init,
 647         .cleanup        = srcu_torture_cleanup,
 648         .readlock       = srcu_torture_read_lock_raw,
 649         .read_delay     = srcu_read_delay,
 650         .readunlock     = srcu_torture_read_unlock_raw,
 651         .completed      = srcu_torture_completed,
 652         .deferred_free  = rcu_sync_torture_deferred_free,
 653         .sync           = srcu_torture_synchronize,
 654         .cb_barrier     = NULL,
 655         .stats          = srcu_torture_stats,
 656         .name           = "srcu_raw"
 657 };
 658
 659 static void srcu_torture_synchronize_expedited(void)
 660 {
 661         synchronize_srcu_expedited(&srcu_ctl);
 662 }
 663
 664 static struct rcu_torture_ops srcu_expedited_ops = {
 665         .init           = srcu_torture_init,
 666         .cleanup        = srcu_torture_cleanup,
 667         .readlock       = srcu_torture_read_lock,
 668         .read_delay     = srcu_read_delay,
 669         .readunlock     = srcu_torture_read_unlock,
 670         .completed      = srcu_torture_completed,
 671         .deferred_free  = rcu_sync_torture_deferred_free,
 672         .sync           = srcu_torture_synchronize_expedited,
 673         .cb_barrier     = NULL,
 674         .stats          = srcu_torture_stats,
 675         .name           = "srcu_expedited"
 676 };
 677
 678 /*
 679  * Definitions for sched torture testing.
 680  */
 681
 682 static int sched_torture_read_lock(void)
 683 {
 684         preempt_disable();
 685         return 0;
 686 }
 687
 688 static void sched_torture_read_unlock(int idx)
 689 {
 690         preempt_enable();
 691 }
 692
 693 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
 694 {
 695         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
 696 }
 697
 698 static struct rcu_torture_ops sched_ops = {
 699         .init           = rcu_sync_torture_init,
 700         .cleanup        = NULL,
 701         .readlock       = sched_torture_read_lock,
 702         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 703         .readunlock     = sched_torture_read_unlock,
 704         .completed      = rcu_no_completed,
 705         .deferred_free  = rcu_sched_torture_deferred_free,
 706         .sync           = synchronize_sched,
 707         .cb_barrier     = rcu_barrier_sched,
 708         .fqs            = rcu_sched_force_quiescent_state,
 709         .stats          = NULL,
 710         .irq_capable    = 1,
 711         .name           = "sched"
 712 };
 713
 714 static struct rcu_torture_ops sched_sync_ops = {
 715         .init           = rcu_sync_torture_init,
 716         .cleanup        = NULL,
 717         .readlock       = sched_torture_read_lock,
 718         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 719         .readunlock     = sched_torture_read_unlock,
 720         .completed      = rcu_no_completed,
 721         .deferred_free  = rcu_sync_torture_deferred_free,
 722         .sync           = synchronize_sched,
 723         .cb_barrier     = NULL,
 724         .fqs            = rcu_sched_force_quiescent_state,
 725         .stats          = NULL,
 726         .name           = "sched_sync"
 727 };
 728
 729 static struct rcu_torture_ops sched_expedited_ops = {
 730         .init           = rcu_sync_torture_init,
 731         .cleanup        = NULL,
 732         .readlock       = sched_torture_read_lock,
 733         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 734         .readunlock     = sched_torture_read_unlock,
 735         .completed      = rcu_no_completed,
 736         .deferred_free  = rcu_sync_torture_deferred_free,
 737         .sync           = synchronize_sched_expedited,
 738         .cb_barrier     = NULL,
 739         .fqs            = rcu_sched_force_quiescent_state,
 740         .stats          = NULL,
 741         .irq_capable    = 1,
 742         .name           = "sched_expedited"
 743 };
 744
 745 /*
 746  * RCU torture priority-boost testing.  Runs one real-time thread per
 747  * CPU for moderate bursts, repeatedly registering RCU callbacks and
 748  * spinning waiting for them to be invoked.  If a given callback takes
 749  * too long to be invoked, we assume that priority inversion has occurred.
 750  */
 751
 752 struct rcu_boost_inflight {
 753         struct rcu_head rcu;
 754         int inflight;
 755 };
 756
 757 static void rcu_torture_boost_cb(struct rcu_head *head)
 758 {
 759         struct rcu_boost_inflight *rbip =
 760                 container_of(head, struct rcu_boost_inflight, rcu);
 761
 762         smp_mb(); /* Ensure RCU-core accesses precede clearing ->inflight */
 763         rbip->inflight = 0;
 764 }
 765
 766 static int rcu_torture_boost(void *arg)
 767 {
 768         unsigned long call_rcu_time;
 769         unsigned long endtime;
 770         unsigned long oldstarttime;
 771         struct rcu_boost_inflight rbi = { .inflight = 0 };
 772         struct sched_param sp;
 773
 774         VERBOSE_PRINTK_STRING("rcu_torture_boost started");
 775
 776         /* Set real-time priority. */
 777         sp.sched_priority = 1;
 778         if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 779                 VERBOSE_PRINTK_STRING("rcu_torture_boost RT prio failed!");
 780                 n_rcu_torture_boost_rterror++;
 781         }
 782
 783         init_rcu_head_on_stack(&rbi.rcu);
 784         /* Each pass through the following loop does one boost-test cycle. */
 785         do {
 786                 /* Wait for the next test interval. */
 787                 oldstarttime = boost_starttime;
 788                 while (ULONG_CMP_LT(jiffies, oldstarttime)) {
 789                         schedule_timeout_uninterruptible(1);
 790                         rcu_stutter_wait("rcu_torture_boost");
 791                         if (kthread_should_stop() ||
 792                             fullstop != FULLSTOP_DONTSTOP)
 793                                 goto checkwait;
 794                 }
 795
 796                 /* Do one boost-test interval. */
 797                 endtime = oldstarttime + test_boost_duration * HZ;
 798                 call_rcu_time = jiffies;
 799                 while (ULONG_CMP_LT(jiffies, endtime)) {
 800                         /* If we don't have a callback in flight, post one. */
 801                         if (!rbi.inflight) {
 802                                 smp_mb(); /* RCU core before ->inflight = 1. */
 803                                 rbi.inflight = 1;
 804                                 call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 805                                 if (jiffies - call_rcu_time >
 806                                          test_boost_duration * HZ - HZ / 2) {
 807                                         VERBOSE_PRINTK_STRING("rcu_torture_boost boosting failed");
 808                                         n_rcu_torture_boost_failure++;
 809                                 }
 810                                 call_rcu_time = jiffies;
 811                         }
 812                         cond_resched();
 813                         rcu_stutter_wait("rcu_torture_boost");
 814                         if (kthread_should_stop() ||
 815                             fullstop != FULLSTOP_DONTSTOP)
 816                                 goto checkwait;
 817                 }
 818
 819                 /*
 820                  * Set the start time of the next test interval.
 821                  * Yes, this is vulnerable to long delays, but such
 822                  * delays simply cause a false negative for the next
 823                  * interval.  Besides, we are running at RT priority,
 824                  * so delays should be relatively rare.
 825                  */
 826                 while (oldstarttime == boost_starttime &&
 827                        !kthread_should_stop()) {
 828                         if (mutex_trylock(&boost_mutex)) {
 829                                 boost_starttime = jiffies +
 830                                                   test_boost_interval * HZ;
 831                                 n_rcu_torture_boosts++;
 832                                 mutex_unlock(&boost_mutex);
 833                                 break;
 834                         }
 835                         schedule_timeout_uninterruptible(1);
 836                 }
 837
 838                 /* Go do the stutter. */
 839 checkwait:      rcu_stutter_wait("rcu_torture_boost");
 840         } while (!kthread_should_stop() && fullstop  == FULLSTOP_DONTSTOP);
 841
 842         /* Clean up and exit. */
 843         VERBOSE_PRINTK_STRING("rcu_torture_boost task stopping");
 844         rcutorture_shutdown_absorb("rcu_torture_boost");
 845         while (!kthread_should_stop() || rbi.inflight)
 846                 schedule_timeout_uninterruptible(1);
 847         smp_mb(); /* order accesses to ->inflight before stack-frame death. */
 848         destroy_rcu_head_on_stack(&rbi.rcu);
 849         return 0;
 850 }
 851
 852 /*
 853  * RCU torture force-quiescent-state kthread.  Repeatedly induces
 854  * bursts of calls to force_quiescent_state(), increasing the probability
 855  * of occurrence of some important types of race conditions.
 856  */
 857 static int
 858 rcu_torture_fqs(void *arg)
 859 {
 860         unsigned long fqs_resume_time;
 861         int fqs_burst_remaining;
 862
 863         VERBOSE_PRINTK_STRING("rcu_torture_fqs task started");
 864         do {
 865                 fqs_resume_time = jiffies + fqs_stutter * HZ;
 866                 while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
 867                        !kthread_should_stop()) {
 868                         schedule_timeout_interruptible(1);
 869                 }
 870                 fqs_burst_remaining = fqs_duration;
 871                 while (fqs_burst_remaining > 0 &&
 872                        !kthread_should_stop()) {
 873                         cur_ops->fqs();
 874                         udelay(fqs_holdoff);
 875                         fqs_burst_remaining -= fqs_holdoff;
 876                 }
 877                 rcu_stutter_wait("rcu_torture_fqs");
 878         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 879         VERBOSE_PRINTK_STRING("rcu_torture_fqs task stopping");
 880         rcutorture_shutdown_absorb("rcu_torture_fqs");
 881         while (!kthread_should_stop())
 882                 schedule_timeout_uninterruptible(1);
 883         return 0;
 884 }
 885
 886 /*
 887  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 888  * for that pointed to by rcu_torture_current, freeing the old structure
 889  * after a series of grace periods (the "pipeline").
 890  */
 891 static int
 892 rcu_torture_writer(void *arg)
 893 {
 894         int i;
 895         long oldbatch = rcu_batches_completed();
 896         struct rcu_torture *rp;
 897         struct rcu_torture *old_rp;
 898         static DEFINE_RCU_RANDOM(rand);
 899
 900         VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
 901         set_user_nice(current, 19);
 902
 903         do {
 904                 schedule_timeout_uninterruptible(1);
 905                 rp = rcu_torture_alloc();
 906                 if (rp == NULL)
 907                         continue;
 908                 rp->rtort_pipe_count = 0;
 909                 udelay(rcu_random(&rand) & 0x3ff);
 910                 old_rp = rcu_dereference_check(rcu_torture_current,
 911                                                current == writer_task);
 912                 rp->rtort_mbtest = 1;
 913                 rcu_assign_pointer(rcu_torture_current, rp);
 914                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
 915                 if (old_rp) {
 916                         i = old_rp->rtort_pipe_count;
 917                         if (i > RCU_TORTURE_PIPE_LEN)
 918                                 i = RCU_TORTURE_PIPE_LEN;
 919                         atomic_inc(&rcu_torture_wcount[i]);
 920                         old_rp->rtort_pipe_count++;
 921                         cur_ops->deferred_free(old_rp);
 922                 }
 923                 rcutorture_record_progress(++rcu_torture_current_version);
 924                 oldbatch = cur_ops->completed();
 925                 rcu_stutter_wait("rcu_torture_writer");
 926         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 927         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
 928         rcutorture_shutdown_absorb("rcu_torture_writer");
 929         while (!kthread_should_stop())
 930                 schedule_timeout_uninterruptible(1);
 931         return 0;
 932 }
 933
 934 /*
 935  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
 936  * delay between calls.
 937  */
 938 static int
 939 rcu_torture_fakewriter(void *arg)
 940 {
 941         DEFINE_RCU_RANDOM(rand);
 942
 943         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
 944         set_user_nice(current, 19);
 945
 946         do {
 947                 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
 948                 udelay(rcu_random(&rand) & 0x3ff);
 949                 cur_ops->sync();
 950                 rcu_stutter_wait("rcu_torture_fakewriter");
 951         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 952
 953         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
 954         rcutorture_shutdown_absorb("rcu_torture_fakewriter");
 955         while (!kthread_should_stop())
 956                 schedule_timeout_uninterruptible(1);
 957         return 0;
 958 }
 959
 960 void rcutorture_trace_dump(void)
 961 {
 962         static atomic_t beenhere = ATOMIC_INIT(0);
 963
 964         if (atomic_read(&beenhere))
 965                 return;
 966         if (atomic_xchg(&beenhere, 1) != 0)
 967                 return;
 968         do_trace_rcu_torture_read(cur_ops->name, (struct rcu_head *)~0UL);
 969         ftrace_dump(DUMP_ALL);
 970 }
 971
 972 /*
 973  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
 974  * incrementing the corresponding element of the pipeline array.  The
 975  * counter in the element should never be greater than 1, otherwise, the
 976  * RCU implementation is broken.
 977  */
 978 static void rcu_torture_timer(unsigned long unused)
 979 {
 980         int idx;
 981         int completed;
 982         static DEFINE_RCU_RANDOM(rand);
 983         static DEFINE_SPINLOCK(rand_lock);
 984         struct rcu_torture *p;
 985         int pipe_count;
 986
 987         idx = cur_ops->readlock();
 988         completed = cur_ops->completed();
 989         p = rcu_dereference_check(rcu_torture_current,
 990                                   rcu_read_lock_bh_held() ||
 991                                   rcu_read_lock_sched_held() ||
 992                                   srcu_read_lock_held(&srcu_ctl));
 993         do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu);
 994         if (p == NULL) {
 995                 /* Leave because rcu_torture_writer is not yet underway */
 996                 cur_ops->readunlock(idx);
 997                 return;
 998         }
 999         if (p->rtort_mbtest == 0)
1000                 atomic_inc(&n_rcu_torture_mberror);
1001         spin_lock(&rand_lock);
1002         cur_ops->read_delay(&rand);
1003         n_rcu_torture_timers++;
1004         spin_unlock(&rand_lock);
1005         preempt_disable();
1006         pipe_count = p->rtort_pipe_count;
1007         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1008                 /* Should not happen, but... */
1009                 pipe_count = RCU_TORTURE_PIPE_LEN;
1010         }
1011         if (pipe_count > 1)
1012                 rcutorture_trace_dump();
1013         __this_cpu_inc(rcu_torture_count[pipe_count]);
1014         completed = cur_ops->completed() - completed;
1015         if (completed > RCU_TORTURE_PIPE_LEN) {
1016                 /* Should not happen, but... */
1017                 completed = RCU_TORTURE_PIPE_LEN;
1018         }
1019         __this_cpu_inc(rcu_torture_batch[completed]);
1020         preempt_enable();
1021         cur_ops->readunlock(idx);
1022 }
1023
1024 /*
1025  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
1026  * incrementing the corresponding element of the pipeline array.  The
1027  * counter in the element should never be greater than 1, otherwise, the
1028  * RCU implementation is broken.
1029  */
1030 static int
1031 rcu_torture_reader(void *arg)
1032 {
1033         int completed;
1034         int idx;
1035         DEFINE_RCU_RANDOM(rand);
1036         struct rcu_torture *p;
1037         int pipe_count;
1038         struct timer_list t;
1039
1040         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
1041         set_user_nice(current, 19);
1042         if (irqreader && cur_ops->irq_capable)
1043                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
1044
1045         do {
1046                 if (irqreader && cur_ops->irq_capable) {
1047                         if (!timer_pending(&t))
1048                                 mod_timer(&t, jiffies + 1);
1049                 }
1050                 idx = cur_ops->readlock();
1051                 completed = cur_ops->completed();
1052                 p = rcu_dereference_check(rcu_torture_current,
1053                                           rcu_read_lock_bh_held() ||
1054                                           rcu_read_lock_sched_held() ||
1055                                           srcu_read_lock_held(&srcu_ctl));
1056                 do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu);
1057                 if (p == NULL) {
1058                         /* Wait for rcu_torture_writer to get underway */
1059                         cur_ops->readunlock(idx);
1060                         schedule_timeout_interruptible(HZ);
1061                         continue;
1062                 }
1063                 if (p->rtort_mbtest == 0)
1064                         atomic_inc(&n_rcu_torture_mberror);
1065                 cur_ops->read_delay(&rand);
1066                 preempt_disable();
1067                 pipe_count = p->rtort_pipe_count;
1068                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1069                         /* Should not happen, but... */
1070                         pipe_count = RCU_TORTURE_PIPE_LEN;
1071                 }
1072                 if (pipe_count > 1)
1073                         rcutorture_trace_dump();
1074                 __this_cpu_inc(rcu_torture_count[pipe_count]);
1075                 completed = cur_ops->completed() - completed;
1076                 if (completed > RCU_TORTURE_PIPE_LEN) {
1077                         /* Should not happen, but... */
1078                         completed = RCU_TORTURE_PIPE_LEN;
1079                 }
1080                 __this_cpu_inc(rcu_torture_batch[completed]);
1081                 preempt_enable();
1082                 cur_ops->readunlock(idx);
1083                 schedule();
1084                 rcu_stutter_wait("rcu_torture_reader");
1085         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1086         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
1087         rcutorture_shutdown_absorb("rcu_torture_reader");
1088         if (irqreader && cur_ops->irq_capable)
1089                 del_timer_sync(&t);
1090         while (!kthread_should_stop())
1091                 schedule_timeout_uninterruptible(1);
1092         return 0;
1093 }
1094
1095 /*
1096  * Create an RCU-torture statistics message in the specified buffer.
1097  */
1098 static int
1099 rcu_torture_printk(char *page)
1100 {
1101         int cnt = 0;
1102         int cpu;
1103         int i;
1104         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1105         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1106
1107         for_each_possible_cpu(cpu) {
1108                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1109                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1110                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1111                 }
1112         }
1113         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1114                 if (pipesummary[i] != 0)
1115                         break;
1116         }
1117         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
1118         cnt += sprintf(&page[cnt],
1119                        "rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d "
1120                        "rtmbe: %d rtbke: %ld rtbre: %ld "
1121                        "rtbf: %ld rtb: %ld nt: %ld "
1122                        "onoff: %ld/%ld:%ld/%ld",
1123                        rcu_torture_current,
1124                        rcu_torture_current_version,
1125                        list_empty(&rcu_torture_freelist),
1126                        atomic_read(&n_rcu_torture_alloc),
1127                        atomic_read(&n_rcu_torture_alloc_fail),
1128                        atomic_read(&n_rcu_torture_free),
1129                        atomic_read(&n_rcu_torture_mberror),
1130                        n_rcu_torture_boost_ktrerror,
1131                        n_rcu_torture_boost_rterror,
1132                        n_rcu_torture_boost_failure,
1133                        n_rcu_torture_boosts,
1134                        n_rcu_torture_timers,
1135                        n_online_successes,
1136                        n_online_attempts,
1137                        n_offline_successes,
1138                        n_offline_attempts);
1139         if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1140             n_rcu_torture_boost_ktrerror != 0 ||
1141             n_rcu_torture_boost_rterror != 0 ||
1142             n_rcu_torture_boost_failure != 0)
1143                 cnt += sprintf(&page[cnt], " !!!");
1144         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1145         if (i > 1) {
1146                 cnt += sprintf(&page[cnt], "!!! ");
1147                 atomic_inc(&n_rcu_torture_error);
1148                 WARN_ON_ONCE(1);
1149         }
1150         cnt += sprintf(&page[cnt], "Reader Pipe: ");
1151         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1152                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
1153         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1154         cnt += sprintf(&page[cnt], "Reader Batch: ");
1155         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1156                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
1157         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1158         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
1159         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1160                 cnt += sprintf(&page[cnt], " %d",
1161                                atomic_read(&rcu_torture_wcount[i]));
1162         }
1163         cnt += sprintf(&page[cnt], "\n");
1164         if (cur_ops->stats)
1165                 cnt += cur_ops->stats(&page[cnt]);
1166         return cnt;
1167 }
1168
1169 /*
1170  * Print torture statistics.  Caller must ensure that there is only
1171  * one call to this function at a given time!!!  This is normally
1172  * accomplished by relying on the module system to only have one copy
1173  * of the module loaded, and then by giving the rcu_torture_stats
1174  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1175  * thread is not running).
1176  */
1177 static void
1178 rcu_torture_stats_print(void)
1179 {
1180         int cnt;
1181
1182         cnt = rcu_torture_printk(printk_buf);
1183         printk(KERN_ALERT "%s", printk_buf);
1184 }
1185
1186 /*
1187  * Periodically prints torture statistics, if periodic statistics printing
1188  * was specified via the stat_interval module parameter.
1189  *
1190  * No need to worry about fullstop here, since this one doesn't reference
1191  * volatile state or register callbacks.
1192  */
1193 static int
1194 rcu_torture_stats(void *arg)
1195 {
1196         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
1197         do {
1198                 schedule_timeout_interruptible(stat_interval * HZ);
1199                 rcu_torture_stats_print();
1200                 rcutorture_shutdown_absorb("rcu_torture_stats");
1201         } while (!kthread_should_stop());
1202         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
1203         return 0;
1204 }
1205
1206 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
1207
1208 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
1209  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
1210  */
1211 static void rcu_torture_shuffle_tasks(void)
1212 {
1213         int i;
1214
1215         cpumask_setall(shuffle_tmp_mask);
1216         get_online_cpus();
1217
1218         /* No point in shuffling if there is only one online CPU (ex: UP) */
1219         if (num_online_cpus() == 1) {
1220                 put_online_cpus();
1221                 return;
1222         }
1223
1224         if (rcu_idle_cpu != -1)
1225                 cpumask_clear_cpu(rcu_idle_cpu, shuffle_tmp_mask);
1226
1227         set_cpus_allowed_ptr(current, shuffle_tmp_mask);
1228
1229         if (reader_tasks) {
1230                 for (i = 0; i < nrealreaders; i++)
1231                         if (reader_tasks[i])
1232                                 set_cpus_allowed_ptr(reader_tasks[i],
1233                                                      shuffle_tmp_mask);
1234         }
1235
1236         if (fakewriter_tasks) {
1237                 for (i = 0; i < nfakewriters; i++)
1238                         if (fakewriter_tasks[i])
1239                                 set_cpus_allowed_ptr(fakewriter_tasks[i],
1240                                                      shuffle_tmp_mask);
1241         }
1242
1243         if (writer_task)
1244                 set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
1245
1246         if (stats_task)
1247                 set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
1248
1249         if (rcu_idle_cpu == -1)
1250                 rcu_idle_cpu = num_online_cpus() - 1;
1251         else
1252                 rcu_idle_cpu--;
1253
1254         put_online_cpus();
1255 }
1256
1257 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
1258  * system to become idle at a time and cut off its timer ticks. This is meant
1259  * to test the support for such tickless idle CPU in RCU.
1260  */
1261 static int
1262 rcu_torture_shuffle(void *arg)
1263 {
1264         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
1265         do {
1266                 schedule_timeout_interruptible(shuffle_interval * HZ);
1267                 rcu_torture_shuffle_tasks();
1268                 rcutorture_shutdown_absorb("rcu_torture_shuffle");
1269         } while (!kthread_should_stop());
1270         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
1271         return 0;
1272 }
1273
1274 /* Cause the rcutorture test to "stutter", starting and stopping all
1275  * threads periodically.
1276  */
1277 static int
1278 rcu_torture_stutter(void *arg)
1279 {
1280         VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
1281         do {
1282                 schedule_timeout_interruptible(stutter * HZ);
1283                 stutter_pause_test = 1;
1284                 if (!kthread_should_stop())
1285                         schedule_timeout_interruptible(stutter * HZ);
1286                 stutter_pause_test = 0;
1287                 rcutorture_shutdown_absorb("rcu_torture_stutter");
1288         } while (!kthread_should_stop());
1289         VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
1290         return 0;
1291 }
1292
1293 static inline void
1294 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, char *tag)
1295 {
1296         printk(KERN_ALERT "%s" TORTURE_FLAG
1297                 "--- %s: nreaders=%d nfakewriters=%d "
1298                 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1299                 "shuffle_interval=%d stutter=%d irqreader=%d "
1300                 "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1301                 "test_boost=%d/%d test_boost_interval=%d "
1302                 "test_boost_duration=%d shutdown_secs=%d "
1303                 "onoff_interval=%d\n",
1304                 torture_type, tag, nrealreaders, nfakewriters,
1305                 stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1306                 stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1307                 test_boost, cur_ops->can_boost,
1308                 test_boost_interval, test_boost_duration, shutdown_secs,
1309                 onoff_interval);
1310 }
1311
1312 static struct notifier_block rcutorture_shutdown_nb = {
1313         .notifier_call = rcutorture_shutdown_notify,
1314 };
1315
1316 static void rcutorture_booster_cleanup(int cpu)
1317 {
1318         struct task_struct *t;
1319
1320         if (boost_tasks[cpu] == NULL)
1321                 return;
1322         mutex_lock(&boost_mutex);
1323         VERBOSE_PRINTK_STRING("Stopping rcu_torture_boost task");
1324         t = boost_tasks[cpu];
1325         boost_tasks[cpu] = NULL;
1326         mutex_unlock(&boost_mutex);
1327
1328         /* This must be outside of the mutex, otherwise deadlock! */
1329         kthread_stop(t);
1330 }
1331
1332 static int rcutorture_booster_init(int cpu)
1333 {
1334         int retval;
1335
1336         if (boost_tasks[cpu] != NULL)
1337                 return 0;  /* Already created, nothing more to do. */
1338
1339         /* Don't allow time recalculation while creating a new task. */
1340         mutex_lock(&boost_mutex);
1341         VERBOSE_PRINTK_STRING("Creating rcu_torture_boost task");
1342         boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1343                                                   cpu_to_node(cpu),
1344                                                   "rcu_torture_boost");
1345         if (IS_ERR(boost_tasks[cpu])) {
1346                 retval = PTR_ERR(boost_tasks[cpu]);
1347                 VERBOSE_PRINTK_STRING("rcu_torture_boost task create failed");
1348                 n_rcu_torture_boost_ktrerror++;
1349                 boost_tasks[cpu] = NULL;
1350                 mutex_unlock(&boost_mutex);
1351                 return retval;
1352         }
1353         kthread_bind(boost_tasks[cpu], cpu);
1354         wake_up_process(boost_tasks[cpu]);
1355         mutex_unlock(&boost_mutex);
1356         return 0;
1357 }
1358
1359 /*
1360  * Cause the rcutorture test to shutdown the system after the test has
1361  * run for the time specified by the shutdown_secs module parameter.
1362  */
1363 static int
1364 rcu_torture_shutdown(void *arg)
1365 {
1366         long delta;
1367         unsigned long jiffies_snap;
1368
1369         VERBOSE_PRINTK_STRING("rcu_torture_shutdown task started");
1370         jiffies_snap = ACCESS_ONCE(jiffies);
1371         while (ULONG_CMP_LT(jiffies_snap, shutdown_time) &&
1372                !kthread_should_stop()) {
1373                 delta = shutdown_time - jiffies_snap;
1374                 if (verbose)
1375                         printk(KERN_ALERT "%s" TORTURE_FLAG
1376                                "rcu_torture_shutdown task: %lu "
1377                                "jiffies remaining\n",
1378                                torture_type, delta);
1379                 schedule_timeout_interruptible(delta);
1380                 jiffies_snap = ACCESS_ONCE(jiffies);
1381         }
1382         if (kthread_should_stop()) {
1383                 VERBOSE_PRINTK_STRING("rcu_torture_shutdown task stopping");
1384                 return 0;
1385         }
1386
1387         /* OK, shut down the system. */
1388
1389         VERBOSE_PRINTK_STRING("rcu_torture_shutdown task shutting down system");
1390         shutdown_task = NULL;   /* Avoid self-kill deadlock. */
1391         rcu_torture_cleanup();  /* Get the success/failure message. */
1392         kernel_power_off();     /* Shut down the system. */
1393         return 0;
1394 }
1395
1396 #ifdef CONFIG_HOTPLUG_CPU
1397
1398 /*
1399  * Execute random CPU-hotplug operations at the interval specified
1400  * by the onoff_interval.
1401  */
1402 static int __cpuinit
1403 rcu_torture_onoff(void *arg)
1404 {
1405         int cpu;
1406         int maxcpu = -1;
1407         DEFINE_RCU_RANDOM(rand);
1408
1409         VERBOSE_PRINTK_STRING("rcu_torture_onoff task started");
1410         for_each_online_cpu(cpu)
1411                 maxcpu = cpu;
1412         WARN_ON(maxcpu < 0);
1413         while (!kthread_should_stop()) {
1414                 cpu = (rcu_random(&rand) >> 4) % (maxcpu + 1);
1415                 if (cpu_online(cpu) && cpu_is_hotpluggable(cpu)) {
1416                         if (verbose)
1417                                 printk(KERN_ALERT "%s" TORTURE_FLAG
1418                                        "rcu_torture_onoff task: offlining %d\n",
1419                                        torture_type, cpu);
1420                         n_offline_attempts++;
1421                         if (cpu_down(cpu) == 0) {
1422                                 if (verbose)
1423                                         printk(KERN_ALERT "%s" TORTURE_FLAG
1424                                                "rcu_torture_onoff task: "
1425                                                "offlined %d\n",
1426                                                torture_type, cpu);
1427                                 n_offline_successes++;
1428                         }
1429                 } else if (cpu_is_hotpluggable(cpu)) {
1430                         if (verbose)
1431                                 printk(KERN_ALERT "%s" TORTURE_FLAG
1432                                        "rcu_torture_onoff task: onlining %d\n",
1433                                        torture_type, cpu);
1434                         n_online_attempts++;
1435                         if (cpu_up(cpu) == 0) {
1436                                 if (verbose)
1437                                         printk(KERN_ALERT "%s" TORTURE_FLAG
1438                                                "rcu_torture_onoff task: "
1439                                                "onlined %d\n",
1440                                                torture_type, cpu);
1441                                 n_online_successes++;
1442                         }
1443                 }
1444                 schedule_timeout_interruptible(onoff_interval * HZ);
1445         }
1446         VERBOSE_PRINTK_STRING("rcu_torture_onoff task stopping");
1447         return 0;
1448 }
1449
1450 static int __cpuinit
1451 rcu_torture_onoff_init(void)
1452 {
1453         if (onoff_interval <= 0)
1454                 return 0;
1455         onoff_task = kthread_run(rcu_torture_onoff, NULL, "rcu_torture_onoff");
1456         if (IS_ERR(onoff_task)) {
1457                 onoff_task = NULL;
1458                 return PTR_ERR(onoff_task);
1459         }
1460         return 0;
1461 }
1462
1463 static void rcu_torture_onoff_cleanup(void)
1464 {
1465         if (onoff_task == NULL)
1466                 return;
1467         VERBOSE_PRINTK_STRING("Stopping rcu_torture_onoff task");
1468         kthread_stop(onoff_task);
1469 }
1470
1471 #else /* #ifdef CONFIG_HOTPLUG_CPU */
1472
1473 static void
1474 rcu_torture_onoff_init(void)
1475 {
1476 }
1477
1478 static void rcu_torture_onoff_cleanup(void)
1479 {
1480 }
1481
1482 #endif /* #else #ifdef CONFIG_HOTPLUG_CPU */
1483
1484 static int rcutorture_cpu_notify(struct notifier_block *self,
1485                                  unsigned long action, void *hcpu)
1486 {
1487         long cpu = (long)hcpu;
1488
1489         switch (action) {
1490         case CPU_ONLINE:
1491         case CPU_DOWN_FAILED:
1492                 (void)rcutorture_booster_init(cpu);
1493                 break;
1494         case CPU_DOWN_PREPARE:
1495                 rcutorture_booster_cleanup(cpu);
1496                 break;
1497         default:
1498                 break;
1499         }
1500         return NOTIFY_OK;
1501 }
1502
1503 static struct notifier_block rcutorture_cpu_nb = {
1504         .notifier_call = rcutorture_cpu_notify,
1505 };
1506
1507 static void
1508 rcu_torture_cleanup(void)
1509 {
1510         int i;
1511
1512         mutex_lock(&fullstop_mutex);
1513         rcutorture_record_test_transition();
1514         if (fullstop == FULLSTOP_SHUTDOWN) {
1515                 printk(KERN_WARNING /* but going down anyway, so... */
1516                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
1517                 mutex_unlock(&fullstop_mutex);
1518                 schedule_timeout_uninterruptible(10);
1519                 if (cur_ops->cb_barrier != NULL)
1520                         cur_ops->cb_barrier();
1521                 return;
1522         }
1523         fullstop = FULLSTOP_RMMOD;
1524         mutex_unlock(&fullstop_mutex);
1525         unregister_reboot_notifier(&rcutorture_shutdown_nb);
1526         if (stutter_task) {
1527                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
1528                 kthread_stop(stutter_task);
1529         }
1530         stutter_task = NULL;
1531         if (shuffler_task) {
1532                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
1533                 kthread_stop(shuffler_task);
1534                 free_cpumask_var(shuffle_tmp_mask);
1535         }
1536         shuffler_task = NULL;
1537
1538         if (writer_task) {
1539                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
1540                 kthread_stop(writer_task);
1541         }
1542         writer_task = NULL;
1543
1544         if (reader_tasks) {
1545                 for (i = 0; i < nrealreaders; i++) {
1546                         if (reader_tasks[i]) {
1547                                 VERBOSE_PRINTK_STRING(
1548                                         "Stopping rcu_torture_reader task");
1549                                 kthread_stop(reader_tasks[i]);
1550                         }
1551                         reader_tasks[i] = NULL;
1552                 }
1553                 kfree(reader_tasks);
1554                 reader_tasks = NULL;
1555         }
1556         rcu_torture_current = NULL;
1557
1558         if (fakewriter_tasks) {
1559                 for (i = 0; i < nfakewriters; i++) {
1560                         if (fakewriter_tasks[i]) {
1561                                 VERBOSE_PRINTK_STRING(
1562                                         "Stopping rcu_torture_fakewriter task");
1563                                 kthread_stop(fakewriter_tasks[i]);
1564                         }
1565                         fakewriter_tasks[i] = NULL;
1566                 }
1567                 kfree(fakewriter_tasks);
1568                 fakewriter_tasks = NULL;
1569         }
1570
1571         if (stats_task) {
1572                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
1573                 kthread_stop(stats_task);
1574         }
1575         stats_task = NULL;
1576
1577         if (fqs_task) {
1578                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_fqs task");
1579                 kthread_stop(fqs_task);
1580         }
1581         fqs_task = NULL;
1582         if ((test_boost == 1 && cur_ops->can_boost) ||
1583             test_boost == 2) {
1584                 unregister_cpu_notifier(&rcutorture_cpu_nb);
1585                 for_each_possible_cpu(i)
1586                         rcutorture_booster_cleanup(i);
1587         }
1588         if (shutdown_task != NULL) {
1589                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shutdown task");
1590                 kthread_stop(shutdown_task);
1591         }
1592         rcu_torture_onoff_cleanup();
1593
1594         /* Wait for all RCU callbacks to fire.  */
1595
1596         if (cur_ops->cb_barrier != NULL)
1597                 cur_ops->cb_barrier();
1598
1599         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1600
1601         if (cur_ops->cleanup)
1602                 cur_ops->cleanup();
1603         if (atomic_read(&n_rcu_torture_error))
1604                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1605         else
1606                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1607 }
1608
1609 static int __init
1610 rcu_torture_init(void)
1611 {
1612         int i;
1613         int cpu;
1614         int firsterr = 0;
1615         static struct rcu_torture_ops *torture_ops[] =
1616                 { &rcu_ops, &rcu_sync_ops, &rcu_expedited_ops,
1617                   &rcu_bh_ops, &rcu_bh_sync_ops, &rcu_bh_expedited_ops,
1618                   &srcu_ops, &srcu_raw_ops, &srcu_expedited_ops,
1619                   &sched_ops, &sched_sync_ops, &sched_expedited_ops, };
1620
1621         mutex_lock(&fullstop_mutex);
1622
1623         /* Process args and tell the world that the torturer is on the job. */
1624         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1625                 cur_ops = torture_ops[i];
1626                 if (strcmp(torture_type, cur_ops->name) == 0)
1627                         break;
1628         }
1629         if (i == ARRAY_SIZE(torture_ops)) {
1630                 printk(KERN_ALERT "rcu-torture: invalid torture type: \"%s\"\n",
1631                        torture_type);
1632                 printk(KERN_ALERT "rcu-torture types:");
1633                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1634                         printk(KERN_ALERT " %s", torture_ops[i]->name);
1635                 printk(KERN_ALERT "\n");
1636                 mutex_unlock(&fullstop_mutex);
1637                 return -EINVAL;
1638         }
1639         if (cur_ops->fqs == NULL && fqs_duration != 0) {
1640                 printk(KERN_ALERT "rcu-torture: ->fqs NULL and non-zero "
1641                                   "fqs_duration, fqs disabled.\n");
1642                 fqs_duration = 0;
1643         }
1644         if (cur_ops->init)
1645                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1646
1647         if (nreaders >= 0)
1648                 nrealreaders = nreaders;
1649         else
1650                 nrealreaders = 2 * num_online_cpus();
1651         rcu_torture_print_module_parms(cur_ops, "Start of test");
1652         fullstop = FULLSTOP_DONTSTOP;
1653
1654         /* Set up the freelist. */
1655
1656         INIT_LIST_HEAD(&rcu_torture_freelist);
1657         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1658                 rcu_tortures[i].rtort_mbtest = 0;
1659                 list_add_tail(&rcu_tortures[i].rtort_free,
1660                               &rcu_torture_freelist);
1661         }
1662
1663         /* Initialize the statistics so that each run gets its own numbers. */
1664
1665         rcu_torture_current = NULL;
1666         rcu_torture_current_version = 0;
1667         atomic_set(&n_rcu_torture_alloc, 0);
1668         atomic_set(&n_rcu_torture_alloc_fail, 0);
1669         atomic_set(&n_rcu_torture_free, 0);
1670         atomic_set(&n_rcu_torture_mberror, 0);
1671         atomic_set(&n_rcu_torture_error, 0);
1672         n_rcu_torture_boost_ktrerror = 0;
1673         n_rcu_torture_boost_rterror = 0;
1674         n_rcu_torture_boost_failure = 0;
1675         n_rcu_torture_boosts = 0;
1676         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1677                 atomic_set(&rcu_torture_wcount[i], 0);
1678         for_each_possible_cpu(cpu) {
1679                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1680                         per_cpu(rcu_torture_count, cpu)[i] = 0;
1681                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
1682                 }
1683         }
1684
1685         /* Start up the kthreads. */
1686
1687         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
1688         writer_task = kthread_run(rcu_torture_writer, NULL,
1689                                   "rcu_torture_writer");
1690         if (IS_ERR(writer_task)) {
1691                 firsterr = PTR_ERR(writer_task);
1692                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
1693                 writer_task = NULL;
1694                 goto unwind;
1695         }
1696         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1697                                    GFP_KERNEL);
1698         if (fakewriter_tasks == NULL) {
1699                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1700                 firsterr = -ENOMEM;
1701                 goto unwind;
1702         }
1703         for (i = 0; i < nfakewriters; i++) {
1704                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
1705                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
1706                                                   "rcu_torture_fakewriter");
1707                 if (IS_ERR(fakewriter_tasks[i])) {
1708                         firsterr = PTR_ERR(fakewriter_tasks[i]);
1709                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
1710                         fakewriter_tasks[i] = NULL;
1711                         goto unwind;
1712                 }
1713         }
1714         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1715                                GFP_KERNEL);
1716         if (reader_tasks == NULL) {
1717                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1718                 firsterr = -ENOMEM;
1719                 goto unwind;
1720         }
1721         for (i = 0; i < nrealreaders; i++) {
1722                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
1723                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
1724                                               "rcu_torture_reader");
1725                 if (IS_ERR(reader_tasks[i])) {
1726                         firsterr = PTR_ERR(reader_tasks[i]);
1727                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
1728                         reader_tasks[i] = NULL;
1729                         goto unwind;
1730                 }
1731         }
1732         if (stat_interval > 0) {
1733                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
1734                 stats_task = kthread_run(rcu_torture_stats, NULL,
1735                                         "rcu_torture_stats");
1736                 if (IS_ERR(stats_task)) {
1737                         firsterr = PTR_ERR(stats_task);
1738                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
1739                         stats_task = NULL;
1740                         goto unwind;
1741                 }
1742         }
1743         if (test_no_idle_hz) {
1744                 rcu_idle_cpu = num_online_cpus() - 1;
1745
1746                 if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
1747                         firsterr = -ENOMEM;
1748                         VERBOSE_PRINTK_ERRSTRING("Failed to alloc mask");
1749                         goto unwind;
1750                 }
1751
1752                 /* Create the shuffler thread */
1753                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
1754                                           "rcu_torture_shuffle");
1755                 if (IS_ERR(shuffler_task)) {
1756                         free_cpumask_var(shuffle_tmp_mask);
1757                         firsterr = PTR_ERR(shuffler_task);
1758                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
1759                         shuffler_task = NULL;
1760                         goto unwind;
1761                 }
1762         }
1763         if (stutter < 0)
1764                 stutter = 0;
1765         if (stutter) {
1766                 /* Create the stutter thread */
1767                 stutter_task = kthread_run(rcu_torture_stutter, NULL,
1768                                           "rcu_torture_stutter");
1769                 if (IS_ERR(stutter_task)) {
1770                         firsterr = PTR_ERR(stutter_task);
1771                         VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
1772                         stutter_task = NULL;
1773                         goto unwind;
1774                 }
1775         }
1776         if (fqs_duration < 0)
1777                 fqs_duration = 0;
1778         if (fqs_duration) {
1779                 /* Create the stutter thread */
1780                 fqs_task = kthread_run(rcu_torture_fqs, NULL,
1781                                        "rcu_torture_fqs");
1782                 if (IS_ERR(fqs_task)) {
1783                         firsterr = PTR_ERR(fqs_task);
1784                         VERBOSE_PRINTK_ERRSTRING("Failed to create fqs");
1785                         fqs_task = NULL;
1786                         goto unwind;
1787                 }
1788         }
1789         if (test_boost_interval < 1)
1790                 test_boost_interval = 1;
1791         if (test_boost_duration < 2)
1792                 test_boost_duration = 2;
1793         if ((test_boost == 1 && cur_ops->can_boost) ||
1794             test_boost == 2) {
1795                 int retval;
1796
1797                 boost_starttime = jiffies + test_boost_interval * HZ;
1798                 register_cpu_notifier(&rcutorture_cpu_nb);
1799                 for_each_possible_cpu(i) {
1800                         if (cpu_is_offline(i))
1801                                 continue;  /* Heuristic: CPU can go offline. */
1802                         retval = rcutorture_booster_init(i);
1803                         if (retval < 0) {
1804                                 firsterr = retval;
1805                                 goto unwind;
1806                         }
1807                 }
1808         }
1809         if (shutdown_secs > 0) {
1810                 shutdown_time = jiffies + shutdown_secs * HZ;
1811                 shutdown_task = kthread_run(rcu_torture_shutdown, NULL,
1812                                             "rcu_torture_shutdown");
1813                 if (IS_ERR(shutdown_task)) {
1814                         firsterr = PTR_ERR(shutdown_task);
1815                         VERBOSE_PRINTK_ERRSTRING("Failed to create shutdown");
1816                         shutdown_task = NULL;
1817                         goto unwind;
1818                 }
1819         }
1820         rcu_torture_onoff_init();
1821         register_reboot_notifier(&rcutorture_shutdown_nb);
1822         rcutorture_record_test_transition();
1823         mutex_unlock(&fullstop_mutex);
1824         return 0;
1825
1826 unwind:
1827         mutex_unlock(&fullstop_mutex);
1828         rcu_torture_cleanup();
1829         return firsterr;
1830 }
1831
1832 module_init(rcu_torture_init);
1833 module_exit(rcu_torture_cleanup);