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 onoff_holdoff;       /* Seconds after boot before CPU hotplugs. */
  69 static int shutdown_secs;       /* Shutdown time (s).  <=0 for no shutdown. */
  70 static int test_boost = 1;      /* Test RCU prio boost: 0=no, 1=maybe, 2=yes. */
  71 static int test_boost_interval = 7; /* Interval between boost tests, seconds. */
  72 static int test_boost_duration = 4; /* Duration of each boost test, seconds. */
  73 static char *torture_type = "rcu"; /* What RCU implementation to torture. */
  74
  75 module_param(nreaders, int, 0444);
  76 MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
  77 module_param(nfakewriters, int, 0444);
  78 MODULE_PARM_DESC(nfakewriters, "Number of RCU fake writer threads");
  79 module_param(stat_interval, int, 0644);
  80 MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
  81 module_param(verbose, bool, 0444);
  82 MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
  83 module_param(test_no_idle_hz, bool, 0444);
  84 MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
  85 module_param(shuffle_interval, int, 0444);
  86 MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
  87 module_param(stutter, int, 0444);
  88 MODULE_PARM_DESC(stutter, "Number of seconds to run/halt test");
  89 module_param(irqreader, int, 0444);
  90 MODULE_PARM_DESC(irqreader, "Allow RCU readers from irq handlers");
  91 module_param(fqs_duration, int, 0444);
  92 MODULE_PARM_DESC(fqs_duration, "Duration of fqs bursts (us)");
  93 module_param(fqs_holdoff, int, 0444);
  94 MODULE_PARM_DESC(fqs_holdoff, "Holdoff time within fqs bursts (us)");
  95 module_param(fqs_stutter, int, 0444);
  96 MODULE_PARM_DESC(fqs_stutter, "Wait time between fqs bursts (s)");
  97 module_param(onoff_interval, int, 0444);
  98 MODULE_PARM_DESC(onoff_interval, "Time between CPU hotplugs (s), 0=disable");
  99 module_param(onoff_holdoff, int, 0444);
 100 MODULE_PARM_DESC(onoff_holdoff, "Time after boot before CPU hotplugs (s)");
 101 module_param(shutdown_secs, int, 0444);
 102 MODULE_PARM_DESC(shutdown_secs, "Shutdown time (s), zero to disable.");
 103 module_param(test_boost, int, 0444);
 104 MODULE_PARM_DESC(test_boost, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
 105 module_param(test_boost_interval, int, 0444);
 106 MODULE_PARM_DESC(test_boost_interval, "Interval between boost tests, seconds.");
 107 module_param(test_boost_duration, int, 0444);
 108 MODULE_PARM_DESC(test_boost_duration, "Duration of each boost test, seconds.");
 109 module_param(torture_type, charp, 0444);
 110 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, srcu)");
 111
 112 #define TORTURE_FLAG "-torture:"
 113 #define PRINTK_STRING(s) \
 114         do { printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
 115 #define VERBOSE_PRINTK_STRING(s) \
 116         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
 117 #define VERBOSE_PRINTK_ERRSTRING(s) \
 118         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
 119
 120 static char printk_buf[4096];
 121
 122 static int nrealreaders;
 123 static struct task_struct *writer_task;
 124 static struct task_struct **fakewriter_tasks;
 125 static struct task_struct **reader_tasks;
 126 static struct task_struct *stats_task;
 127 static struct task_struct *shuffler_task;
 128 static struct task_struct *stutter_task;
 129 static struct task_struct *fqs_task;
 130 static struct task_struct *boost_tasks[NR_CPUS];
 131 static struct task_struct *shutdown_task;
 132 #ifdef CONFIG_HOTPLUG_CPU
 133 static struct task_struct *onoff_task;
 134 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
 135
 136 #define RCU_TORTURE_PIPE_LEN 10
 137
 138 struct rcu_torture {
 139         struct rcu_head rtort_rcu;
 140         int rtort_pipe_count;
 141         struct list_head rtort_free;
 142         int rtort_mbtest;
 143 };
 144
 145 static LIST_HEAD(rcu_torture_freelist);
 146 static struct rcu_torture __rcu *rcu_torture_current;
 147 static unsigned long rcu_torture_current_version;
 148 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 149 static DEFINE_SPINLOCK(rcu_torture_lock);
 150 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
 151         { 0 };
 152 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) =
 153         { 0 };
 154 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 155 static atomic_t n_rcu_torture_alloc;
 156 static atomic_t n_rcu_torture_alloc_fail;
 157 static atomic_t n_rcu_torture_free;
 158 static atomic_t n_rcu_torture_mberror;
 159 static atomic_t n_rcu_torture_error;
 160 static long n_rcu_torture_boost_ktrerror;
 161 static long n_rcu_torture_boost_rterror;
 162 static long n_rcu_torture_boost_failure;
 163 static long n_rcu_torture_boosts;
 164 static long n_rcu_torture_timers;
 165 static long n_offline_attempts;
 166 static long n_offline_successes;
 167 static long n_online_attempts;
 168 static long n_online_successes;
 169 static struct list_head rcu_torture_removed;
 170 static cpumask_var_t shuffle_tmp_mask;
 171
 172 static int stutter_pause_test;
 173
 174 #if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
 175 #define RCUTORTURE_RUNNABLE_INIT 1
 176 #else
 177 #define RCUTORTURE_RUNNABLE_INIT 0
 178 #endif
 179 int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT;
 180 module_param(rcutorture_runnable, int, 0444);
 181 MODULE_PARM_DESC(rcutorture_runnable, "Start rcutorture at boot");
 182
 183 #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
 184 #define rcu_can_boost() 1
 185 #else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 186 #define rcu_can_boost() 0
 187 #endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 188
 189 static unsigned long shutdown_time;     /* jiffies to system shutdown. */
 190 static unsigned long boost_starttime;   /* jiffies of next boost test start. */
 191 DEFINE_MUTEX(boost_mutex);              /* protect setting boost_starttime */
 192                                         /*  and boost task create/destroy. */
 193
 194 /* Mediate rmmod and system shutdown.  Concurrent rmmod & shutdown illegal! */
 195
 196 #define FULLSTOP_DONTSTOP 0     /* Normal operation. */
 197 #define FULLSTOP_SHUTDOWN 1     /* System shutdown with rcutorture running. */
 198 #define FULLSTOP_RMMOD    2     /* Normal rmmod of rcutorture. */
 199 static int fullstop = FULLSTOP_RMMOD;
 200 /*
 201  * Protect fullstop transitions and spawning of kthreads.
 202  */
 203 static DEFINE_MUTEX(fullstop_mutex);
 204
 205 /* Forward reference. */
 206 static void rcu_torture_cleanup(void);
 207
 208 /*
 209  * Detect and respond to a system shutdown.
 210  */
 211 static int
 212 rcutorture_shutdown_notify(struct notifier_block *unused1,
 213                            unsigned long unused2, void *unused3)
 214 {
 215         mutex_lock(&fullstop_mutex);
 216         if (fullstop == FULLSTOP_DONTSTOP)
 217                 fullstop = FULLSTOP_SHUTDOWN;
 218         else
 219                 printk(KERN_WARNING /* but going down anyway, so... */
 220                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
 221         mutex_unlock(&fullstop_mutex);
 222         return NOTIFY_DONE;
 223 }
 224
 225 /*
 226  * Absorb kthreads into a kernel function that won't return, so that
 227  * they won't ever access module text or data again.
 228  */
 229 static void rcutorture_shutdown_absorb(char *title)
 230 {
 231         if (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
 232                 printk(KERN_NOTICE
 233                        "rcutorture thread %s parking due to system shutdown\n",
 234                        title);
 235                 schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
 236         }
 237 }
 238
 239 /*
 240  * Allocate an element from the rcu_tortures pool.
 241  */
 242 static struct rcu_torture *
 243 rcu_torture_alloc(void)
 244 {
 245         struct list_head *p;
 246
 247         spin_lock_bh(&rcu_torture_lock);
 248         if (list_empty(&rcu_torture_freelist)) {
 249                 atomic_inc(&n_rcu_torture_alloc_fail);
 250                 spin_unlock_bh(&rcu_torture_lock);
 251                 return NULL;
 252         }
 253         atomic_inc(&n_rcu_torture_alloc);
 254         p = rcu_torture_freelist.next;
 255         list_del_init(p);
 256         spin_unlock_bh(&rcu_torture_lock);
 257         return container_of(p, struct rcu_torture, rtort_free);
 258 }
 259
 260 /*
 261  * Free an element to the rcu_tortures pool.
 262  */
 263 static void
 264 rcu_torture_free(struct rcu_torture *p)
 265 {
 266         atomic_inc(&n_rcu_torture_free);
 267         spin_lock_bh(&rcu_torture_lock);
 268         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 269         spin_unlock_bh(&rcu_torture_lock);
 270 }
 271
 272 struct rcu_random_state {
 273         unsigned long rrs_state;
 274         long rrs_count;
 275 };
 276
 277 #define RCU_RANDOM_MULT 39916801  /* prime */
 278 #define RCU_RANDOM_ADD  479001701 /* prime */
 279 #define RCU_RANDOM_REFRESH 10000
 280
 281 #define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
 282
 283 /*
 284  * Crude but fast random-number generator.  Uses a linear congruential
 285  * generator, with occasional help from cpu_clock().
 286  */
 287 static unsigned long
 288 rcu_random(struct rcu_random_state *rrsp)
 289 {
 290         if (--rrsp->rrs_count < 0) {
 291                 rrsp->rrs_state += (unsigned long)local_clock();
 292                 rrsp->rrs_count = RCU_RANDOM_REFRESH;
 293         }
 294         rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
 295         return swahw32(rrsp->rrs_state);
 296 }
 297
 298 static void
 299 rcu_stutter_wait(char *title)
 300 {
 301         while (stutter_pause_test || !rcutorture_runnable) {
 302                 if (rcutorture_runnable)
 303                         schedule_timeout_interruptible(1);
 304                 else
 305                         schedule_timeout_interruptible(round_jiffies_relative(HZ));
 306                 rcutorture_shutdown_absorb(title);
 307         }
 308 }
 309
 310 /*
 311  * Operations vector for selecting different types of tests.
 312  */
 313
 314 struct rcu_torture_ops {
 315         void (*init)(void);
 316         void (*cleanup)(void);
 317         int (*readlock)(void);
 318         void (*read_delay)(struct rcu_random_state *rrsp);
 319         void (*readunlock)(int idx);
 320         int (*completed)(void);
 321         void (*deferred_free)(struct rcu_torture *p);
 322         void (*sync)(void);
 323         void (*cb_barrier)(void);
 324         void (*fqs)(void);
 325         int (*stats)(char *page);
 326         int irq_capable;
 327         int can_boost;
 328         char *name;
 329 };
 330
 331 static struct rcu_torture_ops *cur_ops;
 332
 333 /*
 334  * Definitions for rcu torture testing.
 335  */
 336
 337 static int rcu_torture_read_lock(void) __acquires(RCU)
 338 {
 339         rcu_read_lock();
 340         return 0;
 341 }
 342
 343 static void rcu_read_delay(struct rcu_random_state *rrsp)
 344 {
 345         const unsigned long shortdelay_us = 200;
 346         const unsigned long longdelay_ms = 50;
 347
 348         /* We want a short delay sometimes to make a reader delay the grace
 349          * period, and we want a long delay occasionally to trigger
 350          * force_quiescent_state. */
 351
 352         if (!(rcu_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
 353                 mdelay(longdelay_ms);
 354         if (!(rcu_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
 355                 udelay(shortdelay_us);
 356 #ifdef CONFIG_PREEMPT
 357         if (!preempt_count() && !(rcu_random(rrsp) % (nrealreaders * 20000)))
 358                 preempt_schedule();  /* No QS if preempt_disable() in effect */
 359 #endif
 360 }
 361
 362 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 363 {
 364         rcu_read_unlock();
 365 }
 366
 367 static int rcu_torture_completed(void)
 368 {
 369         return rcu_batches_completed();
 370 }
 371
 372 static void
 373 rcu_torture_cb(struct rcu_head *p)
 374 {
 375         int i;
 376         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 377
 378         if (fullstop != FULLSTOP_DONTSTOP) {
 379                 /* Test is ending, just drop callbacks on the floor. */
 380                 /* The next initialization will pick up the pieces. */
 381                 return;
 382         }
 383         i = rp->rtort_pipe_count;
 384         if (i > RCU_TORTURE_PIPE_LEN)
 385                 i = RCU_TORTURE_PIPE_LEN;
 386         atomic_inc(&rcu_torture_wcount[i]);
 387         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 388                 rp->rtort_mbtest = 0;
 389                 rcu_torture_free(rp);
 390         } else
 391                 cur_ops->deferred_free(rp);
 392 }
 393
 394 static int rcu_no_completed(void)
 395 {
 396         return 0;
 397 }
 398
 399 static void rcu_torture_deferred_free(struct rcu_torture *p)
 400 {
 401         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 402 }
 403
 404 static struct rcu_torture_ops rcu_ops = {
 405         .init           = NULL,
 406         .cleanup        = NULL,
 407         .readlock       = rcu_torture_read_lock,
 408         .read_delay     = rcu_read_delay,
 409         .readunlock     = rcu_torture_read_unlock,
 410         .completed      = rcu_torture_completed,
 411         .deferred_free  = rcu_torture_deferred_free,
 412         .sync           = synchronize_rcu,
 413         .cb_barrier     = rcu_barrier,
 414         .fqs            = rcu_force_quiescent_state,
 415         .stats          = NULL,
 416         .irq_capable    = 1,
 417         .can_boost      = rcu_can_boost(),
 418         .name           = "rcu"
 419 };
 420
 421 static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
 422 {
 423         int i;
 424         struct rcu_torture *rp;
 425         struct rcu_torture *rp1;
 426
 427         cur_ops->sync();
 428         list_add(&p->rtort_free, &rcu_torture_removed);
 429         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 430                 i = rp->rtort_pipe_count;
 431                 if (i > RCU_TORTURE_PIPE_LEN)
 432                         i = RCU_TORTURE_PIPE_LEN;
 433                 atomic_inc(&rcu_torture_wcount[i]);
 434                 if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 435                         rp->rtort_mbtest = 0;
 436                         list_del(&rp->rtort_free);
 437                         rcu_torture_free(rp);
 438                 }
 439         }
 440 }
 441
 442 static void rcu_sync_torture_init(void)
 443 {
 444         INIT_LIST_HEAD(&rcu_torture_removed);
 445 }
 446
 447 static struct rcu_torture_ops rcu_sync_ops = {
 448         .init           = rcu_sync_torture_init,
 449         .cleanup        = NULL,
 450         .readlock       = rcu_torture_read_lock,
 451         .read_delay     = rcu_read_delay,
 452         .readunlock     = rcu_torture_read_unlock,
 453         .completed      = rcu_torture_completed,
 454         .deferred_free  = rcu_sync_torture_deferred_free,
 455         .sync           = synchronize_rcu,
 456         .cb_barrier     = NULL,
 457         .fqs            = rcu_force_quiescent_state,
 458         .stats          = NULL,
 459         .irq_capable    = 1,
 460         .can_boost      = rcu_can_boost(),
 461         .name           = "rcu_sync"
 462 };
 463
 464 static struct rcu_torture_ops rcu_expedited_ops = {
 465         .init           = rcu_sync_torture_init,
 466         .cleanup        = NULL,
 467         .readlock       = rcu_torture_read_lock,
 468         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 469         .readunlock     = rcu_torture_read_unlock,
 470         .completed      = rcu_no_completed,
 471         .deferred_free  = rcu_sync_torture_deferred_free,
 472         .sync           = synchronize_rcu_expedited,
 473         .cb_barrier     = NULL,
 474         .fqs            = rcu_force_quiescent_state,
 475         .stats          = NULL,
 476         .irq_capable    = 1,
 477         .can_boost      = rcu_can_boost(),
 478         .name           = "rcu_expedited"
 479 };
 480
 481 /*
 482  * Definitions for rcu_bh torture testing.
 483  */
 484
 485 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
 486 {
 487         rcu_read_lock_bh();
 488         return 0;
 489 }
 490
 491 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
 492 {
 493         rcu_read_unlock_bh();
 494 }
 495
 496 static int rcu_bh_torture_completed(void)
 497 {
 498         return rcu_batches_completed_bh();
 499 }
 500
 501 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 502 {
 503         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
 504 }
 505
 506 static struct rcu_torture_ops rcu_bh_ops = {
 507         .init           = NULL,
 508         .cleanup        = NULL,
 509         .readlock       = rcu_bh_torture_read_lock,
 510         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 511         .readunlock     = rcu_bh_torture_read_unlock,
 512         .completed      = rcu_bh_torture_completed,
 513         .deferred_free  = rcu_bh_torture_deferred_free,
 514         .sync           = synchronize_rcu_bh,
 515         .cb_barrier     = rcu_barrier_bh,
 516         .fqs            = rcu_bh_force_quiescent_state,
 517         .stats          = NULL,
 518         .irq_capable    = 1,
 519         .name           = "rcu_bh"
 520 };
 521
 522 static struct rcu_torture_ops rcu_bh_sync_ops = {
 523         .init           = rcu_sync_torture_init,
 524         .cleanup        = NULL,
 525         .readlock       = rcu_bh_torture_read_lock,
 526         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 527         .readunlock     = rcu_bh_torture_read_unlock,
 528         .completed      = rcu_bh_torture_completed,
 529         .deferred_free  = rcu_sync_torture_deferred_free,
 530         .sync           = synchronize_rcu_bh,
 531         .cb_barrier     = NULL,
 532         .fqs            = rcu_bh_force_quiescent_state,
 533         .stats          = NULL,
 534         .irq_capable    = 1,
 535         .name           = "rcu_bh_sync"
 536 };
 537
 538 static struct rcu_torture_ops rcu_bh_expedited_ops = {
 539         .init           = rcu_sync_torture_init,
 540         .cleanup        = NULL,
 541         .readlock       = rcu_bh_torture_read_lock,
 542         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 543         .readunlock     = rcu_bh_torture_read_unlock,
 544         .completed      = rcu_bh_torture_completed,
 545         .deferred_free  = rcu_sync_torture_deferred_free,
 546         .sync           = synchronize_rcu_bh_expedited,
 547         .cb_barrier     = NULL,
 548         .fqs            = rcu_bh_force_quiescent_state,
 549         .stats          = NULL,
 550         .irq_capable    = 1,
 551         .name           = "rcu_bh_expedited"
 552 };
 553
 554 /*
 555  * Definitions for srcu torture testing.
 556  */
 557
 558 static struct srcu_struct srcu_ctl;
 559
 560 static void srcu_torture_init(void)
 561 {
 562         init_srcu_struct(&srcu_ctl);
 563         rcu_sync_torture_init();
 564 }
 565
 566 static void srcu_torture_cleanup(void)
 567 {
 568         synchronize_srcu(&srcu_ctl);
 569         cleanup_srcu_struct(&srcu_ctl);
 570 }
 571
 572 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
 573 {
 574         return srcu_read_lock(&srcu_ctl);
 575 }
 576
 577 static void srcu_read_delay(struct rcu_random_state *rrsp)
 578 {
 579         long delay;
 580         const long uspertick = 1000000 / HZ;
 581         const long longdelay = 10;
 582
 583         /* We want there to be long-running readers, but not all the time. */
 584
 585         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
 586         if (!delay)
 587                 schedule_timeout_interruptible(longdelay);
 588         else
 589                 rcu_read_delay(rrsp);
 590 }
 591
 592 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
 593 {
 594         srcu_read_unlock(&srcu_ctl, idx);
 595 }
 596
 597 static int srcu_torture_completed(void)
 598 {
 599         return srcu_batches_completed(&srcu_ctl);
 600 }
 601
 602 static void srcu_torture_synchronize(void)
 603 {
 604         synchronize_srcu(&srcu_ctl);
 605 }
 606
 607 static int srcu_torture_stats(char *page)
 608 {
 609         int cnt = 0;
 610         int cpu;
 611         int idx = srcu_ctl.completed & 0x1;
 612
 613         cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
 614                        torture_type, TORTURE_FLAG, idx);
 615         for_each_possible_cpu(cpu) {
 616                 cnt += sprintf(&page[cnt], " %d(%d,%d)", cpu,
 617                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
 618                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
 619         }
 620         cnt += sprintf(&page[cnt], "\n");
 621         return cnt;
 622 }
 623
 624 static struct rcu_torture_ops srcu_ops = {
 625         .init           = srcu_torture_init,
 626         .cleanup        = srcu_torture_cleanup,
 627         .readlock       = srcu_torture_read_lock,
 628         .read_delay     = srcu_read_delay,
 629         .readunlock     = srcu_torture_read_unlock,
 630         .completed      = srcu_torture_completed,
 631         .deferred_free  = rcu_sync_torture_deferred_free,
 632         .sync           = srcu_torture_synchronize,
 633         .cb_barrier     = NULL,
 634         .stats          = srcu_torture_stats,
 635         .name           = "srcu"
 636 };
 637
 638 static int srcu_torture_read_lock_raw(void) __acquires(&srcu_ctl)
 639 {
 640         return srcu_read_lock_raw(&srcu_ctl);
 641 }
 642
 643 static void srcu_torture_read_unlock_raw(int idx) __releases(&srcu_ctl)
 644 {
 645         srcu_read_unlock_raw(&srcu_ctl, idx);
 646 }
 647
 648 static struct rcu_torture_ops srcu_raw_ops = {
 649         .init           = srcu_torture_init,
 650         .cleanup        = srcu_torture_cleanup,
 651         .readlock       = srcu_torture_read_lock_raw,
 652         .read_delay     = srcu_read_delay,
 653         .readunlock     = srcu_torture_read_unlock_raw,
 654         .completed      = srcu_torture_completed,
 655         .deferred_free  = rcu_sync_torture_deferred_free,
 656         .sync           = srcu_torture_synchronize,
 657         .cb_barrier     = NULL,
 658         .stats          = srcu_torture_stats,
 659         .name           = "srcu_raw"
 660 };
 661
 662 static void srcu_torture_synchronize_expedited(void)
 663 {
 664         synchronize_srcu_expedited(&srcu_ctl);
 665 }
 666
 667 static struct rcu_torture_ops srcu_expedited_ops = {
 668         .init           = srcu_torture_init,
 669         .cleanup        = srcu_torture_cleanup,
 670         .readlock       = srcu_torture_read_lock,
 671         .read_delay     = srcu_read_delay,
 672         .readunlock     = srcu_torture_read_unlock,
 673         .completed      = srcu_torture_completed,
 674         .deferred_free  = rcu_sync_torture_deferred_free,
 675         .sync           = srcu_torture_synchronize_expedited,
 676         .cb_barrier     = NULL,
 677         .stats          = srcu_torture_stats,
 678         .name           = "srcu_expedited"
 679 };
 680
 681 /*
 682  * Definitions for sched torture testing.
 683  */
 684
 685 static int sched_torture_read_lock(void)
 686 {
 687         preempt_disable();
 688         return 0;
 689 }
 690
 691 static void sched_torture_read_unlock(int idx)
 692 {
 693         preempt_enable();
 694 }
 695
 696 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
 697 {
 698         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
 699 }
 700
 701 static struct rcu_torture_ops sched_ops = {
 702         .init           = rcu_sync_torture_init,
 703         .cleanup        = NULL,
 704         .readlock       = sched_torture_read_lock,
 705         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 706         .readunlock     = sched_torture_read_unlock,
 707         .completed      = rcu_no_completed,
 708         .deferred_free  = rcu_sched_torture_deferred_free,
 709         .sync           = synchronize_sched,
 710         .cb_barrier     = rcu_barrier_sched,
 711         .fqs            = rcu_sched_force_quiescent_state,
 712         .stats          = NULL,
 713         .irq_capable    = 1,
 714         .name           = "sched"
 715 };
 716
 717 static struct rcu_torture_ops sched_sync_ops = {
 718         .init           = rcu_sync_torture_init,
 719         .cleanup        = NULL,
 720         .readlock       = sched_torture_read_lock,
 721         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 722         .readunlock     = sched_torture_read_unlock,
 723         .completed      = rcu_no_completed,
 724         .deferred_free  = rcu_sync_torture_deferred_free,
 725         .sync           = synchronize_sched,
 726         .cb_barrier     = NULL,
 727         .fqs            = rcu_sched_force_quiescent_state,
 728         .stats          = NULL,
 729         .name           = "sched_sync"
 730 };
 731
 732 static struct rcu_torture_ops sched_expedited_ops = {
 733         .init           = rcu_sync_torture_init,
 734         .cleanup        = NULL,
 735         .readlock       = sched_torture_read_lock,
 736         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 737         .readunlock     = sched_torture_read_unlock,
 738         .completed      = rcu_no_completed,
 739         .deferred_free  = rcu_sync_torture_deferred_free,
 740         .sync           = synchronize_sched_expedited,
 741         .cb_barrier     = NULL,
 742         .fqs            = rcu_sched_force_quiescent_state,
 743         .stats          = NULL,
 744         .irq_capable    = 1,
 745         .name           = "sched_expedited"
 746 };
 747
 748 /*
 749  * RCU torture priority-boost testing.  Runs one real-time thread per
 750  * CPU for moderate bursts, repeatedly registering RCU callbacks and
 751  * spinning waiting for them to be invoked.  If a given callback takes
 752  * too long to be invoked, we assume that priority inversion has occurred.
 753  */
 754
 755 struct rcu_boost_inflight {
 756         struct rcu_head rcu;
 757         int inflight;
 758 };
 759
 760 static void rcu_torture_boost_cb(struct rcu_head *head)
 761 {
 762         struct rcu_boost_inflight *rbip =
 763                 container_of(head, struct rcu_boost_inflight, rcu);
 764
 765         smp_mb(); /* Ensure RCU-core accesses precede clearing ->inflight */
 766         rbip->inflight = 0;
 767 }
 768
 769 static int rcu_torture_boost(void *arg)
 770 {
 771         unsigned long call_rcu_time;
 772         unsigned long endtime;
 773         unsigned long oldstarttime;
 774         struct rcu_boost_inflight rbi = { .inflight = 0 };
 775         struct sched_param sp;
 776
 777         VERBOSE_PRINTK_STRING("rcu_torture_boost started");
 778
 779         /* Set real-time priority. */
 780         sp.sched_priority = 1;
 781         if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 782                 VERBOSE_PRINTK_STRING("rcu_torture_boost RT prio failed!");
 783                 n_rcu_torture_boost_rterror++;
 784         }
 785
 786         init_rcu_head_on_stack(&rbi.rcu);
 787         /* Each pass through the following loop does one boost-test cycle. */
 788         do {
 789                 /* Wait for the next test interval. */
 790                 oldstarttime = boost_starttime;
 791                 while (ULONG_CMP_LT(jiffies, oldstarttime)) {
 792                         schedule_timeout_uninterruptible(1);
 793                         rcu_stutter_wait("rcu_torture_boost");
 794                         if (kthread_should_stop() ||
 795                             fullstop != FULLSTOP_DONTSTOP)
 796                                 goto checkwait;
 797                 }
 798
 799                 /* Do one boost-test interval. */
 800                 endtime = oldstarttime + test_boost_duration * HZ;
 801                 call_rcu_time = jiffies;
 802                 while (ULONG_CMP_LT(jiffies, endtime)) {
 803                         /* If we don't have a callback in flight, post one. */
 804                         if (!rbi.inflight) {
 805                                 smp_mb(); /* RCU core before ->inflight = 1. */
 806                                 rbi.inflight = 1;
 807                                 call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 808                                 if (jiffies - call_rcu_time >
 809                                          test_boost_duration * HZ - HZ / 2) {
 810                                         VERBOSE_PRINTK_STRING("rcu_torture_boost boosting failed");
 811                                         n_rcu_torture_boost_failure++;
 812                                 }
 813                                 call_rcu_time = jiffies;
 814                         }
 815                         cond_resched();
 816                         rcu_stutter_wait("rcu_torture_boost");
 817                         if (kthread_should_stop() ||
 818                             fullstop != FULLSTOP_DONTSTOP)
 819                                 goto checkwait;
 820                 }
 821
 822                 /*
 823                  * Set the start time of the next test interval.
 824                  * Yes, this is vulnerable to long delays, but such
 825                  * delays simply cause a false negative for the next
 826                  * interval.  Besides, we are running at RT priority,
 827                  * so delays should be relatively rare.
 828                  */
 829                 while (oldstarttime == boost_starttime &&
 830                        !kthread_should_stop()) {
 831                         if (mutex_trylock(&boost_mutex)) {
 832                                 boost_starttime = jiffies +
 833                                                   test_boost_interval * HZ;
 834                                 n_rcu_torture_boosts++;
 835                                 mutex_unlock(&boost_mutex);
 836                                 break;
 837                         }
 838                         schedule_timeout_uninterruptible(1);
 839                 }
 840
 841                 /* Go do the stutter. */
 842 checkwait:      rcu_stutter_wait("rcu_torture_boost");
 843         } while (!kthread_should_stop() && fullstop  == FULLSTOP_DONTSTOP);
 844
 845         /* Clean up and exit. */
 846         VERBOSE_PRINTK_STRING("rcu_torture_boost task stopping");
 847         rcutorture_shutdown_absorb("rcu_torture_boost");
 848         while (!kthread_should_stop() || rbi.inflight)
 849                 schedule_timeout_uninterruptible(1);
 850         smp_mb(); /* order accesses to ->inflight before stack-frame death. */
 851         destroy_rcu_head_on_stack(&rbi.rcu);
 852         return 0;
 853 }
 854
 855 /*
 856  * RCU torture force-quiescent-state kthread.  Repeatedly induces
 857  * bursts of calls to force_quiescent_state(), increasing the probability
 858  * of occurrence of some important types of race conditions.
 859  */
 860 static int
 861 rcu_torture_fqs(void *arg)
 862 {
 863         unsigned long fqs_resume_time;
 864         int fqs_burst_remaining;
 865
 866         VERBOSE_PRINTK_STRING("rcu_torture_fqs task started");
 867         do {
 868                 fqs_resume_time = jiffies + fqs_stutter * HZ;
 869                 while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
 870                        !kthread_should_stop()) {
 871                         schedule_timeout_interruptible(1);
 872                 }
 873                 fqs_burst_remaining = fqs_duration;
 874                 while (fqs_burst_remaining > 0 &&
 875                        !kthread_should_stop()) {
 876                         cur_ops->fqs();
 877                         udelay(fqs_holdoff);
 878                         fqs_burst_remaining -= fqs_holdoff;
 879                 }
 880                 rcu_stutter_wait("rcu_torture_fqs");
 881         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 882         VERBOSE_PRINTK_STRING("rcu_torture_fqs task stopping");
 883         rcutorture_shutdown_absorb("rcu_torture_fqs");
 884         while (!kthread_should_stop())
 885                 schedule_timeout_uninterruptible(1);
 886         return 0;
 887 }
 888
 889 /*
 890  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 891  * for that pointed to by rcu_torture_current, freeing the old structure
 892  * after a series of grace periods (the "pipeline").
 893  */
 894 static int
 895 rcu_torture_writer(void *arg)
 896 {
 897         int i;
 898         long oldbatch = rcu_batches_completed();
 899         struct rcu_torture *rp;
 900         struct rcu_torture *old_rp;
 901         static DEFINE_RCU_RANDOM(rand);
 902
 903         VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
 904         set_user_nice(current, 19);
 905
 906         do {
 907                 schedule_timeout_uninterruptible(1);
 908                 rp = rcu_torture_alloc();
 909                 if (rp == NULL)
 910                         continue;
 911                 rp->rtort_pipe_count = 0;
 912                 udelay(rcu_random(&rand) & 0x3ff);
 913                 old_rp = rcu_dereference_check(rcu_torture_current,
 914                                                current == writer_task);
 915                 rp->rtort_mbtest = 1;
 916                 rcu_assign_pointer(rcu_torture_current, rp);
 917                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
 918                 if (old_rp) {
 919                         i = old_rp->rtort_pipe_count;
 920                         if (i > RCU_TORTURE_PIPE_LEN)
 921                                 i = RCU_TORTURE_PIPE_LEN;
 922                         atomic_inc(&rcu_torture_wcount[i]);
 923                         old_rp->rtort_pipe_count++;
 924                         cur_ops->deferred_free(old_rp);
 925                 }
 926                 rcutorture_record_progress(++rcu_torture_current_version);
 927                 oldbatch = cur_ops->completed();
 928                 rcu_stutter_wait("rcu_torture_writer");
 929         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 930         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
 931         rcutorture_shutdown_absorb("rcu_torture_writer");
 932         while (!kthread_should_stop())
 933                 schedule_timeout_uninterruptible(1);
 934         return 0;
 935 }
 936
 937 /*
 938  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
 939  * delay between calls.
 940  */
 941 static int
 942 rcu_torture_fakewriter(void *arg)
 943 {
 944         DEFINE_RCU_RANDOM(rand);
 945
 946         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
 947         set_user_nice(current, 19);
 948
 949         do {
 950                 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
 951                 udelay(rcu_random(&rand) & 0x3ff);
 952                 cur_ops->sync();
 953                 rcu_stutter_wait("rcu_torture_fakewriter");
 954         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 955
 956         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
 957         rcutorture_shutdown_absorb("rcu_torture_fakewriter");
 958         while (!kthread_should_stop())
 959                 schedule_timeout_uninterruptible(1);
 960         return 0;
 961 }
 962
 963 void rcutorture_trace_dump(void)
 964 {
 965         static atomic_t beenhere = ATOMIC_INIT(0);
 966
 967         if (atomic_read(&beenhere))
 968                 return;
 969         if (atomic_xchg(&beenhere, 1) != 0)
 970                 return;
 971         do_trace_rcu_torture_read(cur_ops->name, (struct rcu_head *)~0UL);
 972         ftrace_dump(DUMP_ALL);
 973 }
 974
 975 /*
 976  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
 977  * incrementing the corresponding element of the pipeline array.  The
 978  * counter in the element should never be greater than 1, otherwise, the
 979  * RCU implementation is broken.
 980  */
 981 static void rcu_torture_timer(unsigned long unused)
 982 {
 983         int idx;
 984         int completed;
 985         static DEFINE_RCU_RANDOM(rand);
 986         static DEFINE_SPINLOCK(rand_lock);
 987         struct rcu_torture *p;
 988         int pipe_count;
 989
 990         idx = cur_ops->readlock();
 991         completed = cur_ops->completed();
 992         p = rcu_dereference_check(rcu_torture_current,
 993                                   rcu_read_lock_bh_held() ||
 994                                   rcu_read_lock_sched_held() ||
 995                                   srcu_read_lock_held(&srcu_ctl));
 996         do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu);
 997         if (p == NULL) {
 998                 /* Leave because rcu_torture_writer is not yet underway */
 999                 cur_ops->readunlock(idx);
1000                 return;
1001         }
1002         if (p->rtort_mbtest == 0)
1003                 atomic_inc(&n_rcu_torture_mberror);
1004         spin_lock(&rand_lock);
1005         cur_ops->read_delay(&rand);
1006         n_rcu_torture_timers++;
1007         spin_unlock(&rand_lock);
1008         preempt_disable();
1009         pipe_count = p->rtort_pipe_count;
1010         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1011                 /* Should not happen, but... */
1012                 pipe_count = RCU_TORTURE_PIPE_LEN;
1013         }
1014         if (pipe_count > 1)
1015                 rcutorture_trace_dump();
1016         __this_cpu_inc(rcu_torture_count[pipe_count]);
1017         completed = cur_ops->completed() - completed;
1018         if (completed > RCU_TORTURE_PIPE_LEN) {
1019                 /* Should not happen, but... */
1020                 completed = RCU_TORTURE_PIPE_LEN;
1021         }
1022         __this_cpu_inc(rcu_torture_batch[completed]);
1023         preempt_enable();
1024         cur_ops->readunlock(idx);
1025 }
1026
1027 /*
1028  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
1029  * incrementing the corresponding element of the pipeline array.  The
1030  * counter in the element should never be greater than 1, otherwise, the
1031  * RCU implementation is broken.
1032  */
1033 static int
1034 rcu_torture_reader(void *arg)
1035 {
1036         int completed;
1037         int idx;
1038         DEFINE_RCU_RANDOM(rand);
1039         struct rcu_torture *p;
1040         int pipe_count;
1041         struct timer_list t;
1042
1043         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
1044         set_user_nice(current, 19);
1045         if (irqreader && cur_ops->irq_capable)
1046                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
1047
1048         do {
1049                 if (irqreader && cur_ops->irq_capable) {
1050                         if (!timer_pending(&t))
1051                                 mod_timer(&t, jiffies + 1);
1052                 }
1053                 idx = cur_ops->readlock();
1054                 completed = cur_ops->completed();
1055                 p = rcu_dereference_check(rcu_torture_current,
1056                                           rcu_read_lock_bh_held() ||
1057                                           rcu_read_lock_sched_held() ||
1058                                           srcu_read_lock_held(&srcu_ctl));
1059                 do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu);
1060                 if (p == NULL) {
1061                         /* Wait for rcu_torture_writer to get underway */
1062                         cur_ops->readunlock(idx);
1063                         schedule_timeout_interruptible(HZ);
1064                         continue;
1065                 }
1066                 if (p->rtort_mbtest == 0)
1067                         atomic_inc(&n_rcu_torture_mberror);
1068                 cur_ops->read_delay(&rand);
1069                 preempt_disable();
1070                 pipe_count = p->rtort_pipe_count;
1071                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1072                         /* Should not happen, but... */
1073                         pipe_count = RCU_TORTURE_PIPE_LEN;
1074                 }
1075                 if (pipe_count > 1)
1076                         rcutorture_trace_dump();
1077                 __this_cpu_inc(rcu_torture_count[pipe_count]);
1078                 completed = cur_ops->completed() - completed;
1079                 if (completed > RCU_TORTURE_PIPE_LEN) {
1080                         /* Should not happen, but... */
1081                         completed = RCU_TORTURE_PIPE_LEN;
1082                 }
1083                 __this_cpu_inc(rcu_torture_batch[completed]);
1084                 preempt_enable();
1085                 cur_ops->readunlock(idx);
1086                 schedule();
1087                 rcu_stutter_wait("rcu_torture_reader");
1088         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1089         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
1090         rcutorture_shutdown_absorb("rcu_torture_reader");
1091         if (irqreader && cur_ops->irq_capable)
1092                 del_timer_sync(&t);
1093         while (!kthread_should_stop())
1094                 schedule_timeout_uninterruptible(1);
1095         return 0;
1096 }
1097
1098 /*
1099  * Create an RCU-torture statistics message in the specified buffer.
1100  */
1101 static int
1102 rcu_torture_printk(char *page)
1103 {
1104         int cnt = 0;
1105         int cpu;
1106         int i;
1107         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1108         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1109
1110         for_each_possible_cpu(cpu) {
1111                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1112                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1113                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1114                 }
1115         }
1116         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1117                 if (pipesummary[i] != 0)
1118                         break;
1119         }
1120         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
1121         cnt += sprintf(&page[cnt],
1122                        "rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d "
1123                        "rtmbe: %d rtbke: %ld rtbre: %ld "
1124                        "rtbf: %ld rtb: %ld nt: %ld "
1125                        "onoff: %ld/%ld:%ld/%ld",
1126                        rcu_torture_current,
1127                        rcu_torture_current_version,
1128                        list_empty(&rcu_torture_freelist),
1129                        atomic_read(&n_rcu_torture_alloc),
1130                        atomic_read(&n_rcu_torture_alloc_fail),
1131                        atomic_read(&n_rcu_torture_free),
1132                        atomic_read(&n_rcu_torture_mberror),
1133                        n_rcu_torture_boost_ktrerror,
1134                        n_rcu_torture_boost_rterror,
1135                        n_rcu_torture_boost_failure,
1136                        n_rcu_torture_boosts,
1137                        n_rcu_torture_timers,
1138                        n_online_successes,
1139                        n_online_attempts,
1140                        n_offline_successes,
1141                        n_offline_attempts);
1142         if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1143             n_rcu_torture_boost_ktrerror != 0 ||
1144             n_rcu_torture_boost_rterror != 0 ||
1145             n_rcu_torture_boost_failure != 0)
1146                 cnt += sprintf(&page[cnt], " !!!");
1147         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1148         if (i > 1) {
1149                 cnt += sprintf(&page[cnt], "!!! ");
1150                 atomic_inc(&n_rcu_torture_error);
1151                 WARN_ON_ONCE(1);
1152         }
1153         cnt += sprintf(&page[cnt], "Reader Pipe: ");
1154         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1155                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
1156         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1157         cnt += sprintf(&page[cnt], "Reader Batch: ");
1158         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1159                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
1160         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1161         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
1162         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1163                 cnt += sprintf(&page[cnt], " %d",
1164                                atomic_read(&rcu_torture_wcount[i]));
1165         }
1166         cnt += sprintf(&page[cnt], "\n");
1167         if (cur_ops->stats)
1168                 cnt += cur_ops->stats(&page[cnt]);
1169         return cnt;
1170 }
1171
1172 /*
1173  * Print torture statistics.  Caller must ensure that there is only
1174  * one call to this function at a given time!!!  This is normally
1175  * accomplished by relying on the module system to only have one copy
1176  * of the module loaded, and then by giving the rcu_torture_stats
1177  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1178  * thread is not running).
1179  */
1180 static void
1181 rcu_torture_stats_print(void)
1182 {
1183         int cnt;
1184
1185         cnt = rcu_torture_printk(printk_buf);
1186         printk(KERN_ALERT "%s", printk_buf);
1187 }
1188
1189 /*
1190  * Periodically prints torture statistics, if periodic statistics printing
1191  * was specified via the stat_interval module parameter.
1192  *
1193  * No need to worry about fullstop here, since this one doesn't reference
1194  * volatile state or register callbacks.
1195  */
1196 static int
1197 rcu_torture_stats(void *arg)
1198 {
1199         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
1200         do {
1201                 schedule_timeout_interruptible(stat_interval * HZ);
1202                 rcu_torture_stats_print();
1203                 rcutorture_shutdown_absorb("rcu_torture_stats");
1204         } while (!kthread_should_stop());
1205         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
1206         return 0;
1207 }
1208
1209 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
1210
1211 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
1212  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
1213  */
1214 static void rcu_torture_shuffle_tasks(void)
1215 {
1216         int i;
1217
1218         cpumask_setall(shuffle_tmp_mask);
1219         get_online_cpus();
1220
1221         /* No point in shuffling if there is only one online CPU (ex: UP) */
1222         if (num_online_cpus() == 1) {
1223                 put_online_cpus();
1224                 return;
1225         }
1226
1227         if (rcu_idle_cpu != -1)
1228                 cpumask_clear_cpu(rcu_idle_cpu, shuffle_tmp_mask);
1229
1230         set_cpus_allowed_ptr(current, shuffle_tmp_mask);
1231
1232         if (reader_tasks) {
1233                 for (i = 0; i < nrealreaders; i++)
1234                         if (reader_tasks[i])
1235                                 set_cpus_allowed_ptr(reader_tasks[i],
1236                                                      shuffle_tmp_mask);
1237         }
1238
1239         if (fakewriter_tasks) {
1240                 for (i = 0; i < nfakewriters; i++)
1241                         if (fakewriter_tasks[i])
1242                                 set_cpus_allowed_ptr(fakewriter_tasks[i],
1243                                                      shuffle_tmp_mask);
1244         }
1245
1246         if (writer_task)
1247                 set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
1248
1249         if (stats_task)
1250                 set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
1251
1252         if (rcu_idle_cpu == -1)
1253                 rcu_idle_cpu = num_online_cpus() - 1;
1254         else
1255                 rcu_idle_cpu--;
1256
1257         put_online_cpus();
1258 }
1259
1260 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
1261  * system to become idle at a time and cut off its timer ticks. This is meant
1262  * to test the support for such tickless idle CPU in RCU.
1263  */
1264 static int
1265 rcu_torture_shuffle(void *arg)
1266 {
1267         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
1268         do {
1269                 schedule_timeout_interruptible(shuffle_interval * HZ);
1270                 rcu_torture_shuffle_tasks();
1271                 rcutorture_shutdown_absorb("rcu_torture_shuffle");
1272         } while (!kthread_should_stop());
1273         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
1274         return 0;
1275 }
1276
1277 /* Cause the rcutorture test to "stutter", starting and stopping all
1278  * threads periodically.
1279  */
1280 static int
1281 rcu_torture_stutter(void *arg)
1282 {
1283         VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
1284         do {
1285                 schedule_timeout_interruptible(stutter * HZ);
1286                 stutter_pause_test = 1;
1287                 if (!kthread_should_stop())
1288                         schedule_timeout_interruptible(stutter * HZ);
1289                 stutter_pause_test = 0;
1290                 rcutorture_shutdown_absorb("rcu_torture_stutter");
1291         } while (!kthread_should_stop());
1292         VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
1293         return 0;
1294 }
1295
1296 static inline void
1297 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, char *tag)
1298 {
1299         printk(KERN_ALERT "%s" TORTURE_FLAG
1300                 "--- %s: nreaders=%d nfakewriters=%d "
1301                 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1302                 "shuffle_interval=%d stutter=%d irqreader=%d "
1303                 "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1304                 "test_boost=%d/%d test_boost_interval=%d "
1305                 "test_boost_duration=%d shutdown_secs=%d "
1306                 "onoff_interval=%d onoff_holdoff=%d\n",
1307                 torture_type, tag, nrealreaders, nfakewriters,
1308                 stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1309                 stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1310                 test_boost, cur_ops->can_boost,
1311                 test_boost_interval, test_boost_duration, shutdown_secs,
1312                 onoff_interval, onoff_holdoff);
1313 }
1314
1315 static struct notifier_block rcutorture_shutdown_nb = {
1316         .notifier_call = rcutorture_shutdown_notify,
1317 };
1318
1319 static void rcutorture_booster_cleanup(int cpu)
1320 {
1321         struct task_struct *t;
1322
1323         if (boost_tasks[cpu] == NULL)
1324                 return;
1325         mutex_lock(&boost_mutex);
1326         VERBOSE_PRINTK_STRING("Stopping rcu_torture_boost task");
1327         t = boost_tasks[cpu];
1328         boost_tasks[cpu] = NULL;
1329         mutex_unlock(&boost_mutex);
1330
1331         /* This must be outside of the mutex, otherwise deadlock! */
1332         kthread_stop(t);
1333 }
1334
1335 static int rcutorture_booster_init(int cpu)
1336 {
1337         int retval;
1338
1339         if (boost_tasks[cpu] != NULL)
1340                 return 0;  /* Already created, nothing more to do. */
1341
1342         /* Don't allow time recalculation while creating a new task. */
1343         mutex_lock(&boost_mutex);
1344         VERBOSE_PRINTK_STRING("Creating rcu_torture_boost task");
1345         boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1346                                                   cpu_to_node(cpu),
1347                                                   "rcu_torture_boost");
1348         if (IS_ERR(boost_tasks[cpu])) {
1349                 retval = PTR_ERR(boost_tasks[cpu]);
1350                 VERBOSE_PRINTK_STRING("rcu_torture_boost task create failed");
1351                 n_rcu_torture_boost_ktrerror++;
1352                 boost_tasks[cpu] = NULL;
1353                 mutex_unlock(&boost_mutex);
1354                 return retval;
1355         }
1356         kthread_bind(boost_tasks[cpu], cpu);
1357         wake_up_process(boost_tasks[cpu]);
1358         mutex_unlock(&boost_mutex);
1359         return 0;
1360 }
1361
1362 /*
1363  * Cause the rcutorture test to shutdown the system after the test has
1364  * run for the time specified by the shutdown_secs module parameter.
1365  */
1366 static int
1367 rcu_torture_shutdown(void *arg)
1368 {
1369         long delta;
1370         unsigned long jiffies_snap;
1371
1372         VERBOSE_PRINTK_STRING("rcu_torture_shutdown task started");
1373         jiffies_snap = ACCESS_ONCE(jiffies);
1374         while (ULONG_CMP_LT(jiffies_snap, shutdown_time) &&
1375                !kthread_should_stop()) {
1376                 delta = shutdown_time - jiffies_snap;
1377                 if (verbose)
1378                         printk(KERN_ALERT "%s" TORTURE_FLAG
1379                                "rcu_torture_shutdown task: %lu "
1380                                "jiffies remaining\n",
1381                                torture_type, delta);
1382                 schedule_timeout_interruptible(delta);
1383                 jiffies_snap = ACCESS_ONCE(jiffies);
1384         }
1385         if (kthread_should_stop()) {
1386                 VERBOSE_PRINTK_STRING("rcu_torture_shutdown task stopping");
1387                 return 0;
1388         }
1389
1390         /* OK, shut down the system. */
1391
1392         VERBOSE_PRINTK_STRING("rcu_torture_shutdown task shutting down system");
1393         shutdown_task = NULL;   /* Avoid self-kill deadlock. */
1394         rcu_torture_cleanup();  /* Get the success/failure message. */
1395         kernel_power_off();     /* Shut down the system. */
1396         return 0;
1397 }
1398
1399 #ifdef CONFIG_HOTPLUG_CPU
1400
1401 /*
1402  * Execute random CPU-hotplug operations at the interval specified
1403  * by the onoff_interval.
1404  */
1405 static int __cpuinit
1406 rcu_torture_onoff(void *arg)
1407 {
1408         int cpu;
1409         int maxcpu = -1;
1410         DEFINE_RCU_RANDOM(rand);
1411
1412         VERBOSE_PRINTK_STRING("rcu_torture_onoff task started");
1413         for_each_online_cpu(cpu)
1414                 maxcpu = cpu;
1415         WARN_ON(maxcpu < 0);
1416         if (onoff_holdoff > 0) {
1417                 VERBOSE_PRINTK_STRING("rcu_torture_onoff begin holdoff");
1418                 schedule_timeout_interruptible(onoff_holdoff * HZ);
1419                 VERBOSE_PRINTK_STRING("rcu_torture_onoff end holdoff");
1420         }
1421         while (!kthread_should_stop()) {
1422                 cpu = (rcu_random(&rand) >> 4) % (maxcpu + 1);
1423                 if (cpu_online(cpu) && cpu_is_hotpluggable(cpu)) {
1424                         if (verbose)
1425                                 printk(KERN_ALERT "%s" TORTURE_FLAG
1426                                        "rcu_torture_onoff task: offlining %d\n",
1427                                        torture_type, cpu);
1428                         n_offline_attempts++;
1429                         if (cpu_down(cpu) == 0) {
1430                                 if (verbose)
1431                                         printk(KERN_ALERT "%s" TORTURE_FLAG
1432                                                "rcu_torture_onoff task: "
1433                                                "offlined %d\n",
1434                                                torture_type, cpu);
1435                                 n_offline_successes++;
1436                         }
1437                 } else if (cpu_is_hotpluggable(cpu)) {
1438                         if (verbose)
1439                                 printk(KERN_ALERT "%s" TORTURE_FLAG
1440                                        "rcu_torture_onoff task: onlining %d\n",
1441                                        torture_type, cpu);
1442                         n_online_attempts++;
1443                         if (cpu_up(cpu) == 0) {
1444                                 if (verbose)
1445                                         printk(KERN_ALERT "%s" TORTURE_FLAG
1446                                                "rcu_torture_onoff task: "
1447                                                "onlined %d\n",
1448                                                torture_type, cpu);
1449                                 n_online_successes++;
1450                         }
1451                 }
1452                 schedule_timeout_interruptible(onoff_interval * HZ);
1453         }
1454         VERBOSE_PRINTK_STRING("rcu_torture_onoff task stopping");
1455         return 0;
1456 }
1457
1458 static int __cpuinit
1459 rcu_torture_onoff_init(void)
1460 {
1461         if (onoff_interval <= 0)
1462                 return 0;
1463         onoff_task = kthread_run(rcu_torture_onoff, NULL, "rcu_torture_onoff");
1464         if (IS_ERR(onoff_task)) {
1465                 onoff_task = NULL;
1466                 return PTR_ERR(onoff_task);
1467         }
1468         return 0;
1469 }
1470
1471 static void rcu_torture_onoff_cleanup(void)
1472 {
1473         if (onoff_task == NULL)
1474                 return;
1475         VERBOSE_PRINTK_STRING("Stopping rcu_torture_onoff task");
1476         kthread_stop(onoff_task);
1477 }
1478
1479 #else /* #ifdef CONFIG_HOTPLUG_CPU */
1480
1481 static void
1482 rcu_torture_onoff_init(void)
1483 {
1484 }
1485
1486 static void rcu_torture_onoff_cleanup(void)
1487 {
1488 }
1489
1490 #endif /* #else #ifdef CONFIG_HOTPLUG_CPU */
1491
1492 static int rcutorture_cpu_notify(struct notifier_block *self,
1493                                  unsigned long action, void *hcpu)
1494 {
1495         long cpu = (long)hcpu;
1496
1497         switch (action) {
1498         case CPU_ONLINE:
1499         case CPU_DOWN_FAILED:
1500                 (void)rcutorture_booster_init(cpu);
1501                 break;
1502         case CPU_DOWN_PREPARE:
1503                 rcutorture_booster_cleanup(cpu);
1504                 break;
1505         default:
1506                 break;
1507         }
1508         return NOTIFY_OK;
1509 }
1510
1511 static struct notifier_block rcutorture_cpu_nb = {
1512         .notifier_call = rcutorture_cpu_notify,
1513 };
1514
1515 static void
1516 rcu_torture_cleanup(void)
1517 {
1518         int i;
1519
1520         mutex_lock(&fullstop_mutex);
1521         rcutorture_record_test_transition();
1522         if (fullstop == FULLSTOP_SHUTDOWN) {
1523                 printk(KERN_WARNING /* but going down anyway, so... */
1524                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
1525                 mutex_unlock(&fullstop_mutex);
1526                 schedule_timeout_uninterruptible(10);
1527                 if (cur_ops->cb_barrier != NULL)
1528                         cur_ops->cb_barrier();
1529                 return;
1530         }
1531         fullstop = FULLSTOP_RMMOD;
1532         mutex_unlock(&fullstop_mutex);
1533         unregister_reboot_notifier(&rcutorture_shutdown_nb);
1534         if (stutter_task) {
1535                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
1536                 kthread_stop(stutter_task);
1537         }
1538         stutter_task = NULL;
1539         if (shuffler_task) {
1540                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
1541                 kthread_stop(shuffler_task);
1542                 free_cpumask_var(shuffle_tmp_mask);
1543         }
1544         shuffler_task = NULL;
1545
1546         if (writer_task) {
1547                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
1548                 kthread_stop(writer_task);
1549         }
1550         writer_task = NULL;
1551
1552         if (reader_tasks) {
1553                 for (i = 0; i < nrealreaders; i++) {
1554                         if (reader_tasks[i]) {
1555                                 VERBOSE_PRINTK_STRING(
1556                                         "Stopping rcu_torture_reader task");
1557                                 kthread_stop(reader_tasks[i]);
1558                         }
1559                         reader_tasks[i] = NULL;
1560                 }
1561                 kfree(reader_tasks);
1562                 reader_tasks = NULL;
1563         }
1564         rcu_torture_current = NULL;
1565
1566         if (fakewriter_tasks) {
1567                 for (i = 0; i < nfakewriters; i++) {
1568                         if (fakewriter_tasks[i]) {
1569                                 VERBOSE_PRINTK_STRING(
1570                                         "Stopping rcu_torture_fakewriter task");
1571                                 kthread_stop(fakewriter_tasks[i]);
1572                         }
1573                         fakewriter_tasks[i] = NULL;
1574                 }
1575                 kfree(fakewriter_tasks);
1576                 fakewriter_tasks = NULL;
1577         }
1578
1579         if (stats_task) {
1580                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
1581                 kthread_stop(stats_task);
1582         }
1583         stats_task = NULL;
1584
1585         if (fqs_task) {
1586                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_fqs task");
1587                 kthread_stop(fqs_task);
1588         }
1589         fqs_task = NULL;
1590         if ((test_boost == 1 && cur_ops->can_boost) ||
1591             test_boost == 2) {
1592                 unregister_cpu_notifier(&rcutorture_cpu_nb);
1593                 for_each_possible_cpu(i)
1594                         rcutorture_booster_cleanup(i);
1595         }
1596         if (shutdown_task != NULL) {
1597                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shutdown task");
1598                 kthread_stop(shutdown_task);
1599         }
1600         rcu_torture_onoff_cleanup();
1601
1602         /* Wait for all RCU callbacks to fire.  */
1603
1604         if (cur_ops->cb_barrier != NULL)
1605                 cur_ops->cb_barrier();
1606
1607         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1608
1609         if (cur_ops->cleanup)
1610                 cur_ops->cleanup();
1611         if (atomic_read(&n_rcu_torture_error))
1612                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1613         else if (n_online_successes != n_online_attempts ||
1614                  n_offline_successes != n_offline_attempts)
1615                 rcu_torture_print_module_parms(cur_ops,
1616                                                "End of test: RCU_HOTPLUG");
1617         else
1618                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1619 }
1620
1621 static int __init
1622 rcu_torture_init(void)
1623 {
1624         int i;
1625         int cpu;
1626         int firsterr = 0;
1627         static struct rcu_torture_ops *torture_ops[] =
1628                 { &rcu_ops, &rcu_sync_ops, &rcu_expedited_ops,
1629                   &rcu_bh_ops, &rcu_bh_sync_ops, &rcu_bh_expedited_ops,
1630                   &srcu_ops, &srcu_raw_ops, &srcu_expedited_ops,
1631                   &sched_ops, &sched_sync_ops, &sched_expedited_ops, };
1632
1633         mutex_lock(&fullstop_mutex);
1634
1635         /* Process args and tell the world that the torturer is on the job. */
1636         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1637                 cur_ops = torture_ops[i];
1638                 if (strcmp(torture_type, cur_ops->name) == 0)
1639                         break;
1640         }
1641         if (i == ARRAY_SIZE(torture_ops)) {
1642                 printk(KERN_ALERT "rcu-torture: invalid torture type: \"%s\"\n",
1643                        torture_type);
1644                 printk(KERN_ALERT "rcu-torture types:");
1645                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1646                         printk(KERN_ALERT " %s", torture_ops[i]->name);
1647                 printk(KERN_ALERT "\n");
1648                 mutex_unlock(&fullstop_mutex);
1649                 return -EINVAL;
1650         }
1651         if (cur_ops->fqs == NULL && fqs_duration != 0) {
1652                 printk(KERN_ALERT "rcu-torture: ->fqs NULL and non-zero "
1653                                   "fqs_duration, fqs disabled.\n");
1654                 fqs_duration = 0;
1655         }
1656         if (cur_ops->init)
1657                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1658
1659         if (nreaders >= 0)
1660                 nrealreaders = nreaders;
1661         else
1662                 nrealreaders = 2 * num_online_cpus();
1663         rcu_torture_print_module_parms(cur_ops, "Start of test");
1664         fullstop = FULLSTOP_DONTSTOP;
1665
1666         /* Set up the freelist. */
1667
1668         INIT_LIST_HEAD(&rcu_torture_freelist);
1669         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1670                 rcu_tortures[i].rtort_mbtest = 0;
1671                 list_add_tail(&rcu_tortures[i].rtort_free,
1672                               &rcu_torture_freelist);
1673         }
1674
1675         /* Initialize the statistics so that each run gets its own numbers. */
1676
1677         rcu_torture_current = NULL;
1678         rcu_torture_current_version = 0;
1679         atomic_set(&n_rcu_torture_alloc, 0);
1680         atomic_set(&n_rcu_torture_alloc_fail, 0);
1681         atomic_set(&n_rcu_torture_free, 0);
1682         atomic_set(&n_rcu_torture_mberror, 0);
1683         atomic_set(&n_rcu_torture_error, 0);
1684         n_rcu_torture_boost_ktrerror = 0;
1685         n_rcu_torture_boost_rterror = 0;
1686         n_rcu_torture_boost_failure = 0;
1687         n_rcu_torture_boosts = 0;
1688         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1689                 atomic_set(&rcu_torture_wcount[i], 0);
1690         for_each_possible_cpu(cpu) {
1691                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1692                         per_cpu(rcu_torture_count, cpu)[i] = 0;
1693                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
1694                 }
1695         }
1696
1697         /* Start up the kthreads. */
1698
1699         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
1700         writer_task = kthread_run(rcu_torture_writer, NULL,
1701                                   "rcu_torture_writer");
1702         if (IS_ERR(writer_task)) {
1703                 firsterr = PTR_ERR(writer_task);
1704                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
1705                 writer_task = NULL;
1706                 goto unwind;
1707         }
1708         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1709                                    GFP_KERNEL);
1710         if (fakewriter_tasks == NULL) {
1711                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1712                 firsterr = -ENOMEM;
1713                 goto unwind;
1714         }
1715         for (i = 0; i < nfakewriters; i++) {
1716                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
1717                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
1718                                                   "rcu_torture_fakewriter");
1719                 if (IS_ERR(fakewriter_tasks[i])) {
1720                         firsterr = PTR_ERR(fakewriter_tasks[i]);
1721                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
1722                         fakewriter_tasks[i] = NULL;
1723                         goto unwind;
1724                 }
1725         }
1726         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1727                                GFP_KERNEL);
1728         if (reader_tasks == NULL) {
1729                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1730                 firsterr = -ENOMEM;
1731                 goto unwind;
1732         }
1733         for (i = 0; i < nrealreaders; i++) {
1734                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
1735                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
1736                                               "rcu_torture_reader");
1737                 if (IS_ERR(reader_tasks[i])) {
1738                         firsterr = PTR_ERR(reader_tasks[i]);
1739                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
1740                         reader_tasks[i] = NULL;
1741                         goto unwind;
1742                 }
1743         }
1744         if (stat_interval > 0) {
1745                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
1746                 stats_task = kthread_run(rcu_torture_stats, NULL,
1747                                         "rcu_torture_stats");
1748                 if (IS_ERR(stats_task)) {
1749                         firsterr = PTR_ERR(stats_task);
1750                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
1751                         stats_task = NULL;
1752                         goto unwind;
1753                 }
1754         }
1755         if (test_no_idle_hz) {
1756                 rcu_idle_cpu = num_online_cpus() - 1;
1757
1758                 if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
1759                         firsterr = -ENOMEM;
1760                         VERBOSE_PRINTK_ERRSTRING("Failed to alloc mask");
1761                         goto unwind;
1762                 }
1763
1764                 /* Create the shuffler thread */
1765                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
1766                                           "rcu_torture_shuffle");
1767                 if (IS_ERR(shuffler_task)) {
1768                         free_cpumask_var(shuffle_tmp_mask);
1769                         firsterr = PTR_ERR(shuffler_task);
1770                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
1771                         shuffler_task = NULL;
1772                         goto unwind;
1773                 }
1774         }
1775         if (stutter < 0)
1776                 stutter = 0;
1777         if (stutter) {
1778                 /* Create the stutter thread */
1779                 stutter_task = kthread_run(rcu_torture_stutter, NULL,
1780                                           "rcu_torture_stutter");
1781                 if (IS_ERR(stutter_task)) {
1782                         firsterr = PTR_ERR(stutter_task);
1783                         VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
1784                         stutter_task = NULL;
1785                         goto unwind;
1786                 }
1787         }
1788         if (fqs_duration < 0)
1789                 fqs_duration = 0;
1790         if (fqs_duration) {
1791                 /* Create the stutter thread */
1792                 fqs_task = kthread_run(rcu_torture_fqs, NULL,
1793                                        "rcu_torture_fqs");
1794                 if (IS_ERR(fqs_task)) {
1795                         firsterr = PTR_ERR(fqs_task);
1796                         VERBOSE_PRINTK_ERRSTRING("Failed to create fqs");
1797                         fqs_task = NULL;
1798                         goto unwind;
1799                 }
1800         }
1801         if (test_boost_interval < 1)
1802                 test_boost_interval = 1;
1803         if (test_boost_duration < 2)
1804                 test_boost_duration = 2;
1805         if ((test_boost == 1 && cur_ops->can_boost) ||
1806             test_boost == 2) {
1807                 int retval;
1808
1809                 boost_starttime = jiffies + test_boost_interval * HZ;
1810                 register_cpu_notifier(&rcutorture_cpu_nb);
1811                 for_each_possible_cpu(i) {
1812                         if (cpu_is_offline(i))
1813                                 continue;  /* Heuristic: CPU can go offline. */
1814                         retval = rcutorture_booster_init(i);
1815                         if (retval < 0) {
1816                                 firsterr = retval;
1817                                 goto unwind;
1818                         }
1819                 }
1820         }
1821         if (shutdown_secs > 0) {
1822                 shutdown_time = jiffies + shutdown_secs * HZ;
1823                 shutdown_task = kthread_run(rcu_torture_shutdown, NULL,
1824                                             "rcu_torture_shutdown");
1825                 if (IS_ERR(shutdown_task)) {
1826                         firsterr = PTR_ERR(shutdown_task);
1827                         VERBOSE_PRINTK_ERRSTRING("Failed to create shutdown");
1828                         shutdown_task = NULL;
1829                         goto unwind;
1830                 }
1831         }
1832         rcu_torture_onoff_init();
1833         register_reboot_notifier(&rcutorture_shutdown_nb);
1834         rcutorture_record_test_transition();
1835         mutex_unlock(&fullstop_mutex);
1836         return 0;
1837
1838 unwind:
1839         mutex_unlock(&fullstop_mutex);
1840         rcu_torture_cleanup();
1841         return firsterr;
1842 }
1843
1844 module_init(rcu_torture_init);
1845 module_exit(rcu_torture_cleanup);