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 n_barrier_cbs;       /* Number of callbacks to test RCU barriers. */
  68 static int onoff_interval;      /* Wait time between CPU hotplugs, 0=disable. */
  69 static int onoff_holdoff;       /* Seconds after boot before CPU hotplugs. */
  70 static int shutdown_secs;       /* Shutdown time (s).  <=0 for no shutdown. */
  71 static int stall_cpu;           /* CPU-stall duration (s).  0 for no stall. */
  72 static int stall_cpu_holdoff = 10; /* Time to wait until stall (s).  */
  73 static int test_boost = 1;      /* Test RCU prio boost: 0=no, 1=maybe, 2=yes. */
  74 static int test_boost_interval = 7; /* Interval between boost tests, seconds. */
  75 static int test_boost_duration = 4; /* Duration of each boost test, seconds. */
  76 static char *torture_type = "rcu"; /* What RCU implementation to torture. */
  77
  78 module_param(nreaders, int, 0444);
  79 MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
  80 module_param(nfakewriters, int, 0444);
  81 MODULE_PARM_DESC(nfakewriters, "Number of RCU fake writer threads");
  82 module_param(stat_interval, int, 0644);
  83 MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
  84 module_param(verbose, bool, 0444);
  85 MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
  86 module_param(test_no_idle_hz, bool, 0444);
  87 MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
  88 module_param(shuffle_interval, int, 0444);
  89 MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
  90 module_param(stutter, int, 0444);
  91 MODULE_PARM_DESC(stutter, "Number of seconds to run/halt test");
  92 module_param(irqreader, int, 0444);
  93 MODULE_PARM_DESC(irqreader, "Allow RCU readers from irq handlers");
  94 module_param(fqs_duration, int, 0444);
  95 MODULE_PARM_DESC(fqs_duration, "Duration of fqs bursts (us)");
  96 module_param(fqs_holdoff, int, 0444);
  97 MODULE_PARM_DESC(fqs_holdoff, "Holdoff time within fqs bursts (us)");
  98 module_param(fqs_stutter, int, 0444);
  99 MODULE_PARM_DESC(fqs_stutter, "Wait time between fqs bursts (s)");
 100 module_param(n_barrier_cbs, int, 0444);
 101 MODULE_PARM_DESC(n_barrier_cbs, "# of callbacks/kthreads for barrier testing");
 102 module_param(onoff_interval, int, 0444);
 103 MODULE_PARM_DESC(onoff_interval, "Time between CPU hotplugs (s), 0=disable");
 104 module_param(onoff_holdoff, int, 0444);
 105 MODULE_PARM_DESC(onoff_holdoff, "Time after boot before CPU hotplugs (s)");
 106 module_param(shutdown_secs, int, 0444);
 107 MODULE_PARM_DESC(shutdown_secs, "Shutdown time (s), zero to disable.");
 108 module_param(stall_cpu, int, 0444);
 109 MODULE_PARM_DESC(stall_cpu, "Stall duration (s), zero to disable.");
 110 module_param(stall_cpu_holdoff, int, 0444);
 111 MODULE_PARM_DESC(stall_cpu_holdoff, "Time to wait before starting stall (s).");
 112 module_param(test_boost, int, 0444);
 113 MODULE_PARM_DESC(test_boost, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
 114 module_param(test_boost_interval, int, 0444);
 115 MODULE_PARM_DESC(test_boost_interval, "Interval between boost tests, seconds.");
 116 module_param(test_boost_duration, int, 0444);
 117 MODULE_PARM_DESC(test_boost_duration, "Duration of each boost test, seconds.");
 118 module_param(torture_type, charp, 0444);
 119 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, srcu)");
 120
 121 #define TORTURE_FLAG "-torture:"
 122 #define PRINTK_STRING(s) \
 123         do { printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
 124 #define VERBOSE_PRINTK_STRING(s) \
 125         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
 126 #define VERBOSE_PRINTK_ERRSTRING(s) \
 127         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
 128
 129 static char printk_buf[4096];
 130
 131 static int nrealreaders;
 132 static struct task_struct *writer_task;
 133 static struct task_struct **fakewriter_tasks;
 134 static struct task_struct **reader_tasks;
 135 static struct task_struct *stats_task;
 136 static struct task_struct *shuffler_task;
 137 static struct task_struct *stutter_task;
 138 static struct task_struct *fqs_task;
 139 static struct task_struct *boost_tasks[NR_CPUS];
 140 static struct task_struct *shutdown_task;
 141 #ifdef CONFIG_HOTPLUG_CPU
 142 static struct task_struct *onoff_task;
 143 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
 144 static struct task_struct *stall_task;
 145 static struct task_struct **barrier_cbs_tasks;
 146 static struct task_struct *barrier_task;
 147
 148 #define RCU_TORTURE_PIPE_LEN 10
 149
 150 struct rcu_torture {
 151         struct rcu_head rtort_rcu;
 152         int rtort_pipe_count;
 153         struct list_head rtort_free;
 154         int rtort_mbtest;
 155 };
 156
 157 static LIST_HEAD(rcu_torture_freelist);
 158 static struct rcu_torture __rcu *rcu_torture_current;
 159 static unsigned long rcu_torture_current_version;
 160 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 161 static DEFINE_SPINLOCK(rcu_torture_lock);
 162 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
 163         { 0 };
 164 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) =
 165         { 0 };
 166 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 167 static atomic_t n_rcu_torture_alloc;
 168 static atomic_t n_rcu_torture_alloc_fail;
 169 static atomic_t n_rcu_torture_free;
 170 static atomic_t n_rcu_torture_mberror;
 171 static atomic_t n_rcu_torture_error;
 172 static long n_rcu_torture_barrier_error;
 173 static long n_rcu_torture_boost_ktrerror;
 174 static long n_rcu_torture_boost_rterror;
 175 static long n_rcu_torture_boost_failure;
 176 static long n_rcu_torture_boosts;
 177 static long n_rcu_torture_timers;
 178 static long n_offline_attempts;
 179 static long n_offline_successes;
 180 static long n_online_attempts;
 181 static long n_online_successes;
 182 static long n_barrier_attempts;
 183 static long n_barrier_successes;
 184 static struct list_head rcu_torture_removed;
 185 static cpumask_var_t shuffle_tmp_mask;
 186
 187 static int stutter_pause_test;
 188
 189 #if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
 190 #define RCUTORTURE_RUNNABLE_INIT 1
 191 #else
 192 #define RCUTORTURE_RUNNABLE_INIT 0
 193 #endif
 194 int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT;
 195 module_param(rcutorture_runnable, int, 0444);
 196 MODULE_PARM_DESC(rcutorture_runnable, "Start rcutorture at boot");
 197
 198 #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
 199 #define rcu_can_boost() 1
 200 #else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 201 #define rcu_can_boost() 0
 202 #endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 203
 204 static unsigned long shutdown_time;     /* jiffies to system shutdown. */
 205 static unsigned long boost_starttime;   /* jiffies of next boost test start. */
 206 DEFINE_MUTEX(boost_mutex);              /* protect setting boost_starttime */
 207                                         /*  and boost task create/destroy. */
 208 static atomic_t barrier_cbs_count;      /* Barrier callbacks registered. */
 209 static atomic_t barrier_cbs_invoked;    /* Barrier callbacks invoked. */
 210 static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */
 211 static DECLARE_WAIT_QUEUE_HEAD(barrier_wq);
 212
 213 /* Mediate rmmod and system shutdown.  Concurrent rmmod & shutdown illegal! */
 214
 215 #define FULLSTOP_DONTSTOP 0     /* Normal operation. */
 216 #define FULLSTOP_SHUTDOWN 1     /* System shutdown with rcutorture running. */
 217 #define FULLSTOP_RMMOD    2     /* Normal rmmod of rcutorture. */
 218 static int fullstop = FULLSTOP_RMMOD;
 219 /*
 220  * Protect fullstop transitions and spawning of kthreads.
 221  */
 222 static DEFINE_MUTEX(fullstop_mutex);
 223
 224 /* Forward reference. */
 225 static void rcu_torture_cleanup(void);
 226
 227 /*
 228  * Detect and respond to a system shutdown.
 229  */
 230 static int
 231 rcutorture_shutdown_notify(struct notifier_block *unused1,
 232                            unsigned long unused2, void *unused3)
 233 {
 234         mutex_lock(&fullstop_mutex);
 235         if (fullstop == FULLSTOP_DONTSTOP)
 236                 fullstop = FULLSTOP_SHUTDOWN;
 237         else
 238                 printk(KERN_WARNING /* but going down anyway, so... */
 239                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
 240         mutex_unlock(&fullstop_mutex);
 241         return NOTIFY_DONE;
 242 }
 243
 244 /*
 245  * Absorb kthreads into a kernel function that won't return, so that
 246  * they won't ever access module text or data again.
 247  */
 248 static void rcutorture_shutdown_absorb(char *title)
 249 {
 250         if (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
 251                 printk(KERN_NOTICE
 252                        "rcutorture thread %s parking due to system shutdown\n",
 253                        title);
 254                 schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
 255         }
 256 }
 257
 258 /*
 259  * Allocate an element from the rcu_tortures pool.
 260  */
 261 static struct rcu_torture *
 262 rcu_torture_alloc(void)
 263 {
 264         struct list_head *p;
 265
 266         spin_lock_bh(&rcu_torture_lock);
 267         if (list_empty(&rcu_torture_freelist)) {
 268                 atomic_inc(&n_rcu_torture_alloc_fail);
 269                 spin_unlock_bh(&rcu_torture_lock);
 270                 return NULL;
 271         }
 272         atomic_inc(&n_rcu_torture_alloc);
 273         p = rcu_torture_freelist.next;
 274         list_del_init(p);
 275         spin_unlock_bh(&rcu_torture_lock);
 276         return container_of(p, struct rcu_torture, rtort_free);
 277 }
 278
 279 /*
 280  * Free an element to the rcu_tortures pool.
 281  */
 282 static void
 283 rcu_torture_free(struct rcu_torture *p)
 284 {
 285         atomic_inc(&n_rcu_torture_free);
 286         spin_lock_bh(&rcu_torture_lock);
 287         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 288         spin_unlock_bh(&rcu_torture_lock);
 289 }
 290
 291 struct rcu_random_state {
 292         unsigned long rrs_state;
 293         long rrs_count;
 294 };
 295
 296 #define RCU_RANDOM_MULT 39916801  /* prime */
 297 #define RCU_RANDOM_ADD  479001701 /* prime */
 298 #define RCU_RANDOM_REFRESH 10000
 299
 300 #define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
 301
 302 /*
 303  * Crude but fast random-number generator.  Uses a linear congruential
 304  * generator, with occasional help from cpu_clock().
 305  */
 306 static unsigned long
 307 rcu_random(struct rcu_random_state *rrsp)
 308 {
 309         if (--rrsp->rrs_count < 0) {
 310                 rrsp->rrs_state += (unsigned long)local_clock();
 311                 rrsp->rrs_count = RCU_RANDOM_REFRESH;
 312         }
 313         rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
 314         return swahw32(rrsp->rrs_state);
 315 }
 316
 317 static void
 318 rcu_stutter_wait(char *title)
 319 {
 320         while (stutter_pause_test || !rcutorture_runnable) {
 321                 if (rcutorture_runnable)
 322                         schedule_timeout_interruptible(1);
 323                 else
 324                         schedule_timeout_interruptible(round_jiffies_relative(HZ));
 325                 rcutorture_shutdown_absorb(title);
 326         }
 327 }
 328
 329 /*
 330  * Operations vector for selecting different types of tests.
 331  */
 332
 333 struct rcu_torture_ops {
 334         void (*init)(void);
 335         void (*cleanup)(void);
 336         int (*readlock)(void);
 337         void (*read_delay)(struct rcu_random_state *rrsp);
 338         void (*readunlock)(int idx);
 339         int (*completed)(void);
 340         void (*deferred_free)(struct rcu_torture *p);
 341         void (*sync)(void);
 342         void (*call)(struct rcu_head *head, void (*func)(struct rcu_head *rcu));
 343         void (*cb_barrier)(void);
 344         void (*fqs)(void);
 345         int (*stats)(char *page);
 346         int irq_capable;
 347         int can_boost;
 348         char *name;
 349 };
 350
 351 static struct rcu_torture_ops *cur_ops;
 352
 353 /*
 354  * Definitions for rcu torture testing.
 355  */
 356
 357 static int rcu_torture_read_lock(void) __acquires(RCU)
 358 {
 359         rcu_read_lock();
 360         return 0;
 361 }
 362
 363 static void rcu_read_delay(struct rcu_random_state *rrsp)
 364 {
 365         const unsigned long shortdelay_us = 200;
 366         const unsigned long longdelay_ms = 50;
 367
 368         /* We want a short delay sometimes to make a reader delay the grace
 369          * period, and we want a long delay occasionally to trigger
 370          * force_quiescent_state. */
 371
 372         if (!(rcu_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
 373                 mdelay(longdelay_ms);
 374         if (!(rcu_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
 375                 udelay(shortdelay_us);
 376 #ifdef CONFIG_PREEMPT
 377         if (!preempt_count() && !(rcu_random(rrsp) % (nrealreaders * 20000)))
 378                 preempt_schedule();  /* No QS if preempt_disable() in effect */
 379 #endif
 380 }
 381
 382 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 383 {
 384         rcu_read_unlock();
 385 }
 386
 387 static int rcu_torture_completed(void)
 388 {
 389         return rcu_batches_completed();
 390 }
 391
 392 static void
 393 rcu_torture_cb(struct rcu_head *p)
 394 {
 395         int i;
 396         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 397
 398         if (fullstop != FULLSTOP_DONTSTOP) {
 399                 /* Test is ending, just drop callbacks on the floor. */
 400                 /* The next initialization will pick up the pieces. */
 401                 return;
 402         }
 403         i = rp->rtort_pipe_count;
 404         if (i > RCU_TORTURE_PIPE_LEN)
 405                 i = RCU_TORTURE_PIPE_LEN;
 406         atomic_inc(&rcu_torture_wcount[i]);
 407         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 408                 rp->rtort_mbtest = 0;
 409                 rcu_torture_free(rp);
 410         } else
 411                 cur_ops->deferred_free(rp);
 412 }
 413
 414 static int rcu_no_completed(void)
 415 {
 416         return 0;
 417 }
 418
 419 static void rcu_torture_deferred_free(struct rcu_torture *p)
 420 {
 421         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 422 }
 423
 424 static struct rcu_torture_ops rcu_ops = {
 425         .init           = NULL,
 426         .cleanup        = NULL,
 427         .readlock       = rcu_torture_read_lock,
 428         .read_delay     = rcu_read_delay,
 429         .readunlock     = rcu_torture_read_unlock,
 430         .completed      = rcu_torture_completed,
 431         .deferred_free  = rcu_torture_deferred_free,
 432         .sync           = synchronize_rcu,
 433         .call           = call_rcu,
 434         .cb_barrier     = rcu_barrier,
 435         .fqs            = rcu_force_quiescent_state,
 436         .stats          = NULL,
 437         .irq_capable    = 1,
 438         .can_boost      = rcu_can_boost(),
 439         .name           = "rcu"
 440 };
 441
 442 static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
 443 {
 444         int i;
 445         struct rcu_torture *rp;
 446         struct rcu_torture *rp1;
 447
 448         cur_ops->sync();
 449         list_add(&p->rtort_free, &rcu_torture_removed);
 450         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 451                 i = rp->rtort_pipe_count;
 452                 if (i > RCU_TORTURE_PIPE_LEN)
 453                         i = RCU_TORTURE_PIPE_LEN;
 454                 atomic_inc(&rcu_torture_wcount[i]);
 455                 if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 456                         rp->rtort_mbtest = 0;
 457                         list_del(&rp->rtort_free);
 458                         rcu_torture_free(rp);
 459                 }
 460         }
 461 }
 462
 463 static void rcu_sync_torture_init(void)
 464 {
 465         INIT_LIST_HEAD(&rcu_torture_removed);
 466 }
 467
 468 static struct rcu_torture_ops rcu_sync_ops = {
 469         .init           = rcu_sync_torture_init,
 470         .cleanup        = NULL,
 471         .readlock       = rcu_torture_read_lock,
 472         .read_delay     = rcu_read_delay,
 473         .readunlock     = rcu_torture_read_unlock,
 474         .completed      = rcu_torture_completed,
 475         .deferred_free  = rcu_sync_torture_deferred_free,
 476         .sync           = synchronize_rcu,
 477         .call           = NULL,
 478         .cb_barrier     = NULL,
 479         .fqs            = rcu_force_quiescent_state,
 480         .stats          = NULL,
 481         .irq_capable    = 1,
 482         .can_boost      = rcu_can_boost(),
 483         .name           = "rcu_sync"
 484 };
 485
 486 static struct rcu_torture_ops rcu_expedited_ops = {
 487         .init           = rcu_sync_torture_init,
 488         .cleanup        = NULL,
 489         .readlock       = rcu_torture_read_lock,
 490         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 491         .readunlock     = rcu_torture_read_unlock,
 492         .completed      = rcu_no_completed,
 493         .deferred_free  = rcu_sync_torture_deferred_free,
 494         .sync           = synchronize_rcu_expedited,
 495         .call           = NULL,
 496         .cb_barrier     = NULL,
 497         .fqs            = rcu_force_quiescent_state,
 498         .stats          = NULL,
 499         .irq_capable    = 1,
 500         .can_boost      = rcu_can_boost(),
 501         .name           = "rcu_expedited"
 502 };
 503
 504 /*
 505  * Definitions for rcu_bh torture testing.
 506  */
 507
 508 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
 509 {
 510         rcu_read_lock_bh();
 511         return 0;
 512 }
 513
 514 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
 515 {
 516         rcu_read_unlock_bh();
 517 }
 518
 519 static int rcu_bh_torture_completed(void)
 520 {
 521         return rcu_batches_completed_bh();
 522 }
 523
 524 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 525 {
 526         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
 527 }
 528
 529 static struct rcu_torture_ops rcu_bh_ops = {
 530         .init           = NULL,
 531         .cleanup        = NULL,
 532         .readlock       = rcu_bh_torture_read_lock,
 533         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 534         .readunlock     = rcu_bh_torture_read_unlock,
 535         .completed      = rcu_bh_torture_completed,
 536         .deferred_free  = rcu_bh_torture_deferred_free,
 537         .sync           = synchronize_rcu_bh,
 538         .call           = call_rcu_bh,
 539         .cb_barrier     = rcu_barrier_bh,
 540         .fqs            = rcu_bh_force_quiescent_state,
 541         .stats          = NULL,
 542         .irq_capable    = 1,
 543         .name           = "rcu_bh"
 544 };
 545
 546 static struct rcu_torture_ops rcu_bh_sync_ops = {
 547         .init           = rcu_sync_torture_init,
 548         .cleanup        = NULL,
 549         .readlock       = rcu_bh_torture_read_lock,
 550         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 551         .readunlock     = rcu_bh_torture_read_unlock,
 552         .completed      = rcu_bh_torture_completed,
 553         .deferred_free  = rcu_sync_torture_deferred_free,
 554         .sync           = synchronize_rcu_bh,
 555         .call           = NULL,
 556         .cb_barrier     = NULL,
 557         .fqs            = rcu_bh_force_quiescent_state,
 558         .stats          = NULL,
 559         .irq_capable    = 1,
 560         .name           = "rcu_bh_sync"
 561 };
 562
 563 static struct rcu_torture_ops rcu_bh_expedited_ops = {
 564         .init           = rcu_sync_torture_init,
 565         .cleanup        = NULL,
 566         .readlock       = rcu_bh_torture_read_lock,
 567         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 568         .readunlock     = rcu_bh_torture_read_unlock,
 569         .completed      = rcu_bh_torture_completed,
 570         .deferred_free  = rcu_sync_torture_deferred_free,
 571         .sync           = synchronize_rcu_bh_expedited,
 572         .call           = NULL,
 573         .cb_barrier     = NULL,
 574         .fqs            = rcu_bh_force_quiescent_state,
 575         .stats          = NULL,
 576         .irq_capable    = 1,
 577         .name           = "rcu_bh_expedited"
 578 };
 579
 580 /*
 581  * Definitions for srcu torture testing.
 582  */
 583
 584 static struct srcu_struct srcu_ctl;
 585
 586 static void srcu_torture_init(void)
 587 {
 588         init_srcu_struct(&srcu_ctl);
 589         rcu_sync_torture_init();
 590 }
 591
 592 static void srcu_torture_cleanup(void)
 593 {
 594         synchronize_srcu(&srcu_ctl);
 595         cleanup_srcu_struct(&srcu_ctl);
 596 }
 597
 598 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
 599 {
 600         return srcu_read_lock(&srcu_ctl);
 601 }
 602
 603 static void srcu_read_delay(struct rcu_random_state *rrsp)
 604 {
 605         long delay;
 606         const long uspertick = 1000000 / HZ;
 607         const long longdelay = 10;
 608
 609         /* We want there to be long-running readers, but not all the time. */
 610
 611         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
 612         if (!delay)
 613                 schedule_timeout_interruptible(longdelay);
 614         else
 615                 rcu_read_delay(rrsp);
 616 }
 617
 618 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
 619 {
 620         srcu_read_unlock(&srcu_ctl, idx);
 621 }
 622
 623 static int srcu_torture_completed(void)
 624 {
 625         return srcu_batches_completed(&srcu_ctl);
 626 }
 627
 628 static void srcu_torture_synchronize(void)
 629 {
 630         synchronize_srcu(&srcu_ctl);
 631 }
 632
 633 static int srcu_torture_stats(char *page)
 634 {
 635         int cnt = 0;
 636         int cpu;
 637         int idx = srcu_ctl.completed & 0x1;
 638
 639         cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
 640                        torture_type, TORTURE_FLAG, idx);
 641         for_each_possible_cpu(cpu) {
 642                 cnt += sprintf(&page[cnt], " %d(%lu,%lu)", cpu,
 643                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
 644                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
 645         }
 646         cnt += sprintf(&page[cnt], "\n");
 647         return cnt;
 648 }
 649
 650 static struct rcu_torture_ops srcu_ops = {
 651         .init           = srcu_torture_init,
 652         .cleanup        = srcu_torture_cleanup,
 653         .readlock       = srcu_torture_read_lock,
 654         .read_delay     = srcu_read_delay,
 655         .readunlock     = srcu_torture_read_unlock,
 656         .completed      = srcu_torture_completed,
 657         .deferred_free  = rcu_sync_torture_deferred_free,
 658         .sync           = srcu_torture_synchronize,
 659         .call           = NULL,
 660         .cb_barrier     = NULL,
 661         .stats          = srcu_torture_stats,
 662         .name           = "srcu"
 663 };
 664
 665 static int srcu_torture_read_lock_raw(void) __acquires(&srcu_ctl)
 666 {
 667         return srcu_read_lock_raw(&srcu_ctl);
 668 }
 669
 670 static void srcu_torture_read_unlock_raw(int idx) __releases(&srcu_ctl)
 671 {
 672         srcu_read_unlock_raw(&srcu_ctl, idx);
 673 }
 674
 675 static struct rcu_torture_ops srcu_raw_ops = {
 676         .init           = srcu_torture_init,
 677         .cleanup        = srcu_torture_cleanup,
 678         .readlock       = srcu_torture_read_lock_raw,
 679         .read_delay     = srcu_read_delay,
 680         .readunlock     = srcu_torture_read_unlock_raw,
 681         .completed      = srcu_torture_completed,
 682         .deferred_free  = rcu_sync_torture_deferred_free,
 683         .sync           = srcu_torture_synchronize,
 684         .call           = NULL,
 685         .cb_barrier     = NULL,
 686         .stats          = srcu_torture_stats,
 687         .name           = "srcu_raw"
 688 };
 689
 690 static void srcu_torture_synchronize_expedited(void)
 691 {
 692         synchronize_srcu_expedited(&srcu_ctl);
 693 }
 694
 695 static struct rcu_torture_ops srcu_expedited_ops = {
 696         .init           = srcu_torture_init,
 697         .cleanup        = srcu_torture_cleanup,
 698         .readlock       = srcu_torture_read_lock,
 699         .read_delay     = srcu_read_delay,
 700         .readunlock     = srcu_torture_read_unlock,
 701         .completed      = srcu_torture_completed,
 702         .deferred_free  = rcu_sync_torture_deferred_free,
 703         .sync           = srcu_torture_synchronize_expedited,
 704         .call           = NULL,
 705         .cb_barrier     = NULL,
 706         .stats          = srcu_torture_stats,
 707         .name           = "srcu_expedited"
 708 };
 709
 710 /*
 711  * Definitions for sched torture testing.
 712  */
 713
 714 static int sched_torture_read_lock(void)
 715 {
 716         preempt_disable();
 717         return 0;
 718 }
 719
 720 static void sched_torture_read_unlock(int idx)
 721 {
 722         preempt_enable();
 723 }
 724
 725 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
 726 {
 727         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
 728 }
 729
 730 static struct rcu_torture_ops sched_ops = {
 731         .init           = rcu_sync_torture_init,
 732         .cleanup        = NULL,
 733         .readlock       = sched_torture_read_lock,
 734         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 735         .readunlock     = sched_torture_read_unlock,
 736         .completed      = rcu_no_completed,
 737         .deferred_free  = rcu_sched_torture_deferred_free,
 738         .sync           = synchronize_sched,
 739         .cb_barrier     = rcu_barrier_sched,
 740         .fqs            = rcu_sched_force_quiescent_state,
 741         .stats          = NULL,
 742         .irq_capable    = 1,
 743         .name           = "sched"
 744 };
 745
 746 static struct rcu_torture_ops sched_sync_ops = {
 747         .init           = rcu_sync_torture_init,
 748         .cleanup        = NULL,
 749         .readlock       = sched_torture_read_lock,
 750         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 751         .readunlock     = sched_torture_read_unlock,
 752         .completed      = rcu_no_completed,
 753         .deferred_free  = rcu_sync_torture_deferred_free,
 754         .sync           = synchronize_sched,
 755         .cb_barrier     = NULL,
 756         .fqs            = rcu_sched_force_quiescent_state,
 757         .stats          = NULL,
 758         .name           = "sched_sync"
 759 };
 760
 761 static struct rcu_torture_ops sched_expedited_ops = {
 762         .init           = rcu_sync_torture_init,
 763         .cleanup        = NULL,
 764         .readlock       = sched_torture_read_lock,
 765         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 766         .readunlock     = sched_torture_read_unlock,
 767         .completed      = rcu_no_completed,
 768         .deferred_free  = rcu_sync_torture_deferred_free,
 769         .sync           = synchronize_sched_expedited,
 770         .cb_barrier     = NULL,
 771         .fqs            = rcu_sched_force_quiescent_state,
 772         .stats          = NULL,
 773         .irq_capable    = 1,
 774         .name           = "sched_expedited"
 775 };
 776
 777 /*
 778  * RCU torture priority-boost testing.  Runs one real-time thread per
 779  * CPU for moderate bursts, repeatedly registering RCU callbacks and
 780  * spinning waiting for them to be invoked.  If a given callback takes
 781  * too long to be invoked, we assume that priority inversion has occurred.
 782  */
 783
 784 struct rcu_boost_inflight {
 785         struct rcu_head rcu;
 786         int inflight;
 787 };
 788
 789 static void rcu_torture_boost_cb(struct rcu_head *head)
 790 {
 791         struct rcu_boost_inflight *rbip =
 792                 container_of(head, struct rcu_boost_inflight, rcu);
 793
 794         smp_mb(); /* Ensure RCU-core accesses precede clearing ->inflight */
 795         rbip->inflight = 0;
 796 }
 797
 798 static int rcu_torture_boost(void *arg)
 799 {
 800         unsigned long call_rcu_time;
 801         unsigned long endtime;
 802         unsigned long oldstarttime;
 803         struct rcu_boost_inflight rbi = { .inflight = 0 };
 804         struct sched_param sp;
 805
 806         VERBOSE_PRINTK_STRING("rcu_torture_boost started");
 807
 808         /* Set real-time priority. */
 809         sp.sched_priority = 1;
 810         if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 811                 VERBOSE_PRINTK_STRING("rcu_torture_boost RT prio failed!");
 812                 n_rcu_torture_boost_rterror++;
 813         }
 814
 815         init_rcu_head_on_stack(&rbi.rcu);
 816         /* Each pass through the following loop does one boost-test cycle. */
 817         do {
 818                 /* Wait for the next test interval. */
 819                 oldstarttime = boost_starttime;
 820                 while (ULONG_CMP_LT(jiffies, oldstarttime)) {
 821                         schedule_timeout_uninterruptible(1);
 822                         rcu_stutter_wait("rcu_torture_boost");
 823                         if (kthread_should_stop() ||
 824                             fullstop != FULLSTOP_DONTSTOP)
 825                                 goto checkwait;
 826                 }
 827
 828                 /* Do one boost-test interval. */
 829                 endtime = oldstarttime + test_boost_duration * HZ;
 830                 call_rcu_time = jiffies;
 831                 while (ULONG_CMP_LT(jiffies, endtime)) {
 832                         /* If we don't have a callback in flight, post one. */
 833                         if (!rbi.inflight) {
 834                                 smp_mb(); /* RCU core before ->inflight = 1. */
 835                                 rbi.inflight = 1;
 836                                 call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 837                                 if (jiffies - call_rcu_time >
 838                                          test_boost_duration * HZ - HZ / 2) {
 839                                         VERBOSE_PRINTK_STRING("rcu_torture_boost boosting failed");
 840                                         n_rcu_torture_boost_failure++;
 841                                 }
 842                                 call_rcu_time = jiffies;
 843                         }
 844                         cond_resched();
 845                         rcu_stutter_wait("rcu_torture_boost");
 846                         if (kthread_should_stop() ||
 847                             fullstop != FULLSTOP_DONTSTOP)
 848                                 goto checkwait;
 849                 }
 850
 851                 /*
 852                  * Set the start time of the next test interval.
 853                  * Yes, this is vulnerable to long delays, but such
 854                  * delays simply cause a false negative for the next
 855                  * interval.  Besides, we are running at RT priority,
 856                  * so delays should be relatively rare.
 857                  */
 858                 while (oldstarttime == boost_starttime &&
 859                        !kthread_should_stop()) {
 860                         if (mutex_trylock(&boost_mutex)) {
 861                                 boost_starttime = jiffies +
 862                                                   test_boost_interval * HZ;
 863                                 n_rcu_torture_boosts++;
 864                                 mutex_unlock(&boost_mutex);
 865                                 break;
 866                         }
 867                         schedule_timeout_uninterruptible(1);
 868                 }
 869
 870                 /* Go do the stutter. */
 871 checkwait:      rcu_stutter_wait("rcu_torture_boost");
 872         } while (!kthread_should_stop() && fullstop  == FULLSTOP_DONTSTOP);
 873
 874         /* Clean up and exit. */
 875         VERBOSE_PRINTK_STRING("rcu_torture_boost task stopping");
 876         rcutorture_shutdown_absorb("rcu_torture_boost");
 877         while (!kthread_should_stop() || rbi.inflight)
 878                 schedule_timeout_uninterruptible(1);
 879         smp_mb(); /* order accesses to ->inflight before stack-frame death. */
 880         destroy_rcu_head_on_stack(&rbi.rcu);
 881         return 0;
 882 }
 883
 884 /*
 885  * RCU torture force-quiescent-state kthread.  Repeatedly induces
 886  * bursts of calls to force_quiescent_state(), increasing the probability
 887  * of occurrence of some important types of race conditions.
 888  */
 889 static int
 890 rcu_torture_fqs(void *arg)
 891 {
 892         unsigned long fqs_resume_time;
 893         int fqs_burst_remaining;
 894
 895         VERBOSE_PRINTK_STRING("rcu_torture_fqs task started");
 896         do {
 897                 fqs_resume_time = jiffies + fqs_stutter * HZ;
 898                 while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
 899                        !kthread_should_stop()) {
 900                         schedule_timeout_interruptible(1);
 901                 }
 902                 fqs_burst_remaining = fqs_duration;
 903                 while (fqs_burst_remaining > 0 &&
 904                        !kthread_should_stop()) {
 905                         cur_ops->fqs();
 906                         udelay(fqs_holdoff);
 907                         fqs_burst_remaining -= fqs_holdoff;
 908                 }
 909                 rcu_stutter_wait("rcu_torture_fqs");
 910         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 911         VERBOSE_PRINTK_STRING("rcu_torture_fqs task stopping");
 912         rcutorture_shutdown_absorb("rcu_torture_fqs");
 913         while (!kthread_should_stop())
 914                 schedule_timeout_uninterruptible(1);
 915         return 0;
 916 }
 917
 918 /*
 919  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 920  * for that pointed to by rcu_torture_current, freeing the old structure
 921  * after a series of grace periods (the "pipeline").
 922  */
 923 static int
 924 rcu_torture_writer(void *arg)
 925 {
 926         int i;
 927         long oldbatch = rcu_batches_completed();
 928         struct rcu_torture *rp;
 929         struct rcu_torture *old_rp;
 930         static DEFINE_RCU_RANDOM(rand);
 931
 932         VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
 933         set_user_nice(current, 19);
 934
 935         do {
 936                 schedule_timeout_uninterruptible(1);
 937                 rp = rcu_torture_alloc();
 938                 if (rp == NULL)
 939                         continue;
 940                 rp->rtort_pipe_count = 0;
 941                 udelay(rcu_random(&rand) & 0x3ff);
 942                 old_rp = rcu_dereference_check(rcu_torture_current,
 943                                                current == writer_task);
 944                 rp->rtort_mbtest = 1;
 945                 rcu_assign_pointer(rcu_torture_current, rp);
 946                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
 947                 if (old_rp) {
 948                         i = old_rp->rtort_pipe_count;
 949                         if (i > RCU_TORTURE_PIPE_LEN)
 950                                 i = RCU_TORTURE_PIPE_LEN;
 951                         atomic_inc(&rcu_torture_wcount[i]);
 952                         old_rp->rtort_pipe_count++;
 953                         cur_ops->deferred_free(old_rp);
 954                 }
 955                 rcutorture_record_progress(++rcu_torture_current_version);
 956                 oldbatch = cur_ops->completed();
 957                 rcu_stutter_wait("rcu_torture_writer");
 958         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 959         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
 960         rcutorture_shutdown_absorb("rcu_torture_writer");
 961         while (!kthread_should_stop())
 962                 schedule_timeout_uninterruptible(1);
 963         return 0;
 964 }
 965
 966 /*
 967  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
 968  * delay between calls.
 969  */
 970 static int
 971 rcu_torture_fakewriter(void *arg)
 972 {
 973         DEFINE_RCU_RANDOM(rand);
 974
 975         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
 976         set_user_nice(current, 19);
 977
 978         do {
 979                 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
 980                 udelay(rcu_random(&rand) & 0x3ff);
 981                 cur_ops->sync();
 982                 rcu_stutter_wait("rcu_torture_fakewriter");
 983         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 984
 985         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
 986         rcutorture_shutdown_absorb("rcu_torture_fakewriter");
 987         while (!kthread_should_stop())
 988                 schedule_timeout_uninterruptible(1);
 989         return 0;
 990 }
 991
 992 void rcutorture_trace_dump(void)
 993 {
 994         static atomic_t beenhere = ATOMIC_INIT(0);
 995
 996         if (atomic_read(&beenhere))
 997                 return;
 998         if (atomic_xchg(&beenhere, 1) != 0)
 999                 return;
1000         do_trace_rcu_torture_read(cur_ops->name, (struct rcu_head *)~0UL);
1001         ftrace_dump(DUMP_ALL);
1002 }
1003
1004 /*
1005  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
1006  * incrementing the corresponding element of the pipeline array.  The
1007  * counter in the element should never be greater than 1, otherwise, the
1008  * RCU implementation is broken.
1009  */
1010 static void rcu_torture_timer(unsigned long unused)
1011 {
1012         int idx;
1013         int completed;
1014         static DEFINE_RCU_RANDOM(rand);
1015         static DEFINE_SPINLOCK(rand_lock);
1016         struct rcu_torture *p;
1017         int pipe_count;
1018
1019         idx = cur_ops->readlock();
1020         completed = cur_ops->completed();
1021         p = rcu_dereference_check(rcu_torture_current,
1022                                   rcu_read_lock_bh_held() ||
1023                                   rcu_read_lock_sched_held() ||
1024                                   srcu_read_lock_held(&srcu_ctl));
1025         if (p == NULL) {
1026                 /* Leave because rcu_torture_writer is not yet underway */
1027                 cur_ops->readunlock(idx);
1028                 return;
1029         }
1030         do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu);
1031         if (p->rtort_mbtest == 0)
1032                 atomic_inc(&n_rcu_torture_mberror);
1033         spin_lock(&rand_lock);
1034         cur_ops->read_delay(&rand);
1035         n_rcu_torture_timers++;
1036         spin_unlock(&rand_lock);
1037         preempt_disable();
1038         pipe_count = p->rtort_pipe_count;
1039         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1040                 /* Should not happen, but... */
1041                 pipe_count = RCU_TORTURE_PIPE_LEN;
1042         }
1043         if (pipe_count > 1)
1044                 rcutorture_trace_dump();
1045         __this_cpu_inc(rcu_torture_count[pipe_count]);
1046         completed = cur_ops->completed() - completed;
1047         if (completed > RCU_TORTURE_PIPE_LEN) {
1048                 /* Should not happen, but... */
1049                 completed = RCU_TORTURE_PIPE_LEN;
1050         }
1051         __this_cpu_inc(rcu_torture_batch[completed]);
1052         preempt_enable();
1053         cur_ops->readunlock(idx);
1054 }
1055
1056 /*
1057  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
1058  * incrementing the corresponding element of the pipeline array.  The
1059  * counter in the element should never be greater than 1, otherwise, the
1060  * RCU implementation is broken.
1061  */
1062 static int
1063 rcu_torture_reader(void *arg)
1064 {
1065         int completed;
1066         int idx;
1067         DEFINE_RCU_RANDOM(rand);
1068         struct rcu_torture *p;
1069         int pipe_count;
1070         struct timer_list t;
1071
1072         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
1073         set_user_nice(current, 19);
1074         if (irqreader && cur_ops->irq_capable)
1075                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
1076
1077         do {
1078                 if (irqreader && cur_ops->irq_capable) {
1079                         if (!timer_pending(&t))
1080                                 mod_timer(&t, jiffies + 1);
1081                 }
1082                 idx = cur_ops->readlock();
1083                 completed = cur_ops->completed();
1084                 p = rcu_dereference_check(rcu_torture_current,
1085                                           rcu_read_lock_bh_held() ||
1086                                           rcu_read_lock_sched_held() ||
1087                                           srcu_read_lock_held(&srcu_ctl));
1088                 if (p == NULL) {
1089                         /* Wait for rcu_torture_writer to get underway */
1090                         cur_ops->readunlock(idx);
1091                         schedule_timeout_interruptible(HZ);
1092                         continue;
1093                 }
1094                 do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu);
1095                 if (p->rtort_mbtest == 0)
1096                         atomic_inc(&n_rcu_torture_mberror);
1097                 cur_ops->read_delay(&rand);
1098                 preempt_disable();
1099                 pipe_count = p->rtort_pipe_count;
1100                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1101                         /* Should not happen, but... */
1102                         pipe_count = RCU_TORTURE_PIPE_LEN;
1103                 }
1104                 if (pipe_count > 1)
1105                         rcutorture_trace_dump();
1106                 __this_cpu_inc(rcu_torture_count[pipe_count]);
1107                 completed = cur_ops->completed() - completed;
1108                 if (completed > RCU_TORTURE_PIPE_LEN) {
1109                         /* Should not happen, but... */
1110                         completed = RCU_TORTURE_PIPE_LEN;
1111                 }
1112                 __this_cpu_inc(rcu_torture_batch[completed]);
1113                 preempt_enable();
1114                 cur_ops->readunlock(idx);
1115                 schedule();
1116                 rcu_stutter_wait("rcu_torture_reader");
1117         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1118         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
1119         rcutorture_shutdown_absorb("rcu_torture_reader");
1120         if (irqreader && cur_ops->irq_capable)
1121                 del_timer_sync(&t);
1122         while (!kthread_should_stop())
1123                 schedule_timeout_uninterruptible(1);
1124         return 0;
1125 }
1126
1127 /*
1128  * Create an RCU-torture statistics message in the specified buffer.
1129  */
1130 static int
1131 rcu_torture_printk(char *page)
1132 {
1133         int cnt = 0;
1134         int cpu;
1135         int i;
1136         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1137         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1138
1139         for_each_possible_cpu(cpu) {
1140                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1141                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1142                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1143                 }
1144         }
1145         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1146                 if (pipesummary[i] != 0)
1147                         break;
1148         }
1149         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
1150         cnt += sprintf(&page[cnt],
1151                        "rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d "
1152                        "rtmbe: %d rtbke: %ld rtbre: %ld "
1153                        "rtbf: %ld rtb: %ld nt: %ld "
1154                        "onoff: %ld/%ld:%ld/%ld "
1155                        "barrier: %ld/%ld:%ld",
1156                        rcu_torture_current,
1157                        rcu_torture_current_version,
1158                        list_empty(&rcu_torture_freelist),
1159                        atomic_read(&n_rcu_torture_alloc),
1160                        atomic_read(&n_rcu_torture_alloc_fail),
1161                        atomic_read(&n_rcu_torture_free),
1162                        atomic_read(&n_rcu_torture_mberror),
1163                        n_rcu_torture_boost_ktrerror,
1164                        n_rcu_torture_boost_rterror,
1165                        n_rcu_torture_boost_failure,
1166                        n_rcu_torture_boosts,
1167                        n_rcu_torture_timers,
1168                        n_online_successes,
1169                        n_online_attempts,
1170                        n_offline_successes,
1171                        n_offline_attempts,
1172                        n_barrier_successes,
1173                        n_barrier_attempts,
1174                        n_rcu_torture_barrier_error);
1175         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1176         if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1177             n_rcu_torture_barrier_error != 0 ||
1178             n_rcu_torture_boost_ktrerror != 0 ||
1179             n_rcu_torture_boost_rterror != 0 ||
1180             n_rcu_torture_boost_failure != 0 ||
1181             i > 1) {
1182                 cnt += sprintf(&page[cnt], "!!! ");
1183                 atomic_inc(&n_rcu_torture_error);
1184                 WARN_ON_ONCE(1);
1185         }
1186         cnt += sprintf(&page[cnt], "Reader Pipe: ");
1187         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1188                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
1189         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1190         cnt += sprintf(&page[cnt], "Reader Batch: ");
1191         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1192                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
1193         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1194         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
1195         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1196                 cnt += sprintf(&page[cnt], " %d",
1197                                atomic_read(&rcu_torture_wcount[i]));
1198         }
1199         cnt += sprintf(&page[cnt], "\n");
1200         if (cur_ops->stats)
1201                 cnt += cur_ops->stats(&page[cnt]);
1202         return cnt;
1203 }
1204
1205 /*
1206  * Print torture statistics.  Caller must ensure that there is only
1207  * one call to this function at a given time!!!  This is normally
1208  * accomplished by relying on the module system to only have one copy
1209  * of the module loaded, and then by giving the rcu_torture_stats
1210  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1211  * thread is not running).
1212  */
1213 static void
1214 rcu_torture_stats_print(void)
1215 {
1216         int cnt;
1217
1218         cnt = rcu_torture_printk(printk_buf);
1219         printk(KERN_ALERT "%s", printk_buf);
1220 }
1221
1222 /*
1223  * Periodically prints torture statistics, if periodic statistics printing
1224  * was specified via the stat_interval module parameter.
1225  *
1226  * No need to worry about fullstop here, since this one doesn't reference
1227  * volatile state or register callbacks.
1228  */
1229 static int
1230 rcu_torture_stats(void *arg)
1231 {
1232         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
1233         do {
1234                 schedule_timeout_interruptible(stat_interval * HZ);
1235                 rcu_torture_stats_print();
1236                 rcutorture_shutdown_absorb("rcu_torture_stats");
1237         } while (!kthread_should_stop());
1238         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
1239         return 0;
1240 }
1241
1242 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
1243
1244 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
1245  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
1246  */
1247 static void rcu_torture_shuffle_tasks(void)
1248 {
1249         int i;
1250
1251         cpumask_setall(shuffle_tmp_mask);
1252         get_online_cpus();
1253
1254         /* No point in shuffling if there is only one online CPU (ex: UP) */
1255         if (num_online_cpus() == 1) {
1256                 put_online_cpus();
1257                 return;
1258         }
1259
1260         if (rcu_idle_cpu != -1)
1261                 cpumask_clear_cpu(rcu_idle_cpu, shuffle_tmp_mask);
1262
1263         set_cpus_allowed_ptr(current, shuffle_tmp_mask);
1264
1265         if (reader_tasks) {
1266                 for (i = 0; i < nrealreaders; i++)
1267                         if (reader_tasks[i])
1268                                 set_cpus_allowed_ptr(reader_tasks[i],
1269                                                      shuffle_tmp_mask);
1270         }
1271
1272         if (fakewriter_tasks) {
1273                 for (i = 0; i < nfakewriters; i++)
1274                         if (fakewriter_tasks[i])
1275                                 set_cpus_allowed_ptr(fakewriter_tasks[i],
1276                                                      shuffle_tmp_mask);
1277         }
1278
1279         if (writer_task)
1280                 set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
1281
1282         if (stats_task)
1283                 set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
1284
1285         if (rcu_idle_cpu == -1)
1286                 rcu_idle_cpu = num_online_cpus() - 1;
1287         else
1288                 rcu_idle_cpu--;
1289
1290         put_online_cpus();
1291 }
1292
1293 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
1294  * system to become idle at a time and cut off its timer ticks. This is meant
1295  * to test the support for such tickless idle CPU in RCU.
1296  */
1297 static int
1298 rcu_torture_shuffle(void *arg)
1299 {
1300         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
1301         do {
1302                 schedule_timeout_interruptible(shuffle_interval * HZ);
1303                 rcu_torture_shuffle_tasks();
1304                 rcutorture_shutdown_absorb("rcu_torture_shuffle");
1305         } while (!kthread_should_stop());
1306         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
1307         return 0;
1308 }
1309
1310 /* Cause the rcutorture test to "stutter", starting and stopping all
1311  * threads periodically.
1312  */
1313 static int
1314 rcu_torture_stutter(void *arg)
1315 {
1316         VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
1317         do {
1318                 schedule_timeout_interruptible(stutter * HZ);
1319                 stutter_pause_test = 1;
1320                 if (!kthread_should_stop())
1321                         schedule_timeout_interruptible(stutter * HZ);
1322                 stutter_pause_test = 0;
1323                 rcutorture_shutdown_absorb("rcu_torture_stutter");
1324         } while (!kthread_should_stop());
1325         VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
1326         return 0;
1327 }
1328
1329 static inline void
1330 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, char *tag)
1331 {
1332         printk(KERN_ALERT "%s" TORTURE_FLAG
1333                 "--- %s: nreaders=%d nfakewriters=%d "
1334                 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1335                 "shuffle_interval=%d stutter=%d irqreader=%d "
1336                 "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1337                 "test_boost=%d/%d test_boost_interval=%d "
1338                 "test_boost_duration=%d shutdown_secs=%d "
1339                 "onoff_interval=%d onoff_holdoff=%d\n",
1340                 torture_type, tag, nrealreaders, nfakewriters,
1341                 stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1342                 stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1343                 test_boost, cur_ops->can_boost,
1344                 test_boost_interval, test_boost_duration, shutdown_secs,
1345                 onoff_interval, onoff_holdoff);
1346 }
1347
1348 static struct notifier_block rcutorture_shutdown_nb = {
1349         .notifier_call = rcutorture_shutdown_notify,
1350 };
1351
1352 static void rcutorture_booster_cleanup(int cpu)
1353 {
1354         struct task_struct *t;
1355
1356         if (boost_tasks[cpu] == NULL)
1357                 return;
1358         mutex_lock(&boost_mutex);
1359         VERBOSE_PRINTK_STRING("Stopping rcu_torture_boost task");
1360         t = boost_tasks[cpu];
1361         boost_tasks[cpu] = NULL;
1362         mutex_unlock(&boost_mutex);
1363
1364         /* This must be outside of the mutex, otherwise deadlock! */
1365         kthread_stop(t);
1366         boost_tasks[cpu] = NULL;
1367 }
1368
1369 static int rcutorture_booster_init(int cpu)
1370 {
1371         int retval;
1372
1373         if (boost_tasks[cpu] != NULL)
1374                 return 0;  /* Already created, nothing more to do. */
1375
1376         /* Don't allow time recalculation while creating a new task. */
1377         mutex_lock(&boost_mutex);
1378         VERBOSE_PRINTK_STRING("Creating rcu_torture_boost task");
1379         boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1380                                                   cpu_to_node(cpu),
1381                                                   "rcu_torture_boost");
1382         if (IS_ERR(boost_tasks[cpu])) {
1383                 retval = PTR_ERR(boost_tasks[cpu]);
1384                 VERBOSE_PRINTK_STRING("rcu_torture_boost task create failed");
1385                 n_rcu_torture_boost_ktrerror++;
1386                 boost_tasks[cpu] = NULL;
1387                 mutex_unlock(&boost_mutex);
1388                 return retval;
1389         }
1390         kthread_bind(boost_tasks[cpu], cpu);
1391         wake_up_process(boost_tasks[cpu]);
1392         mutex_unlock(&boost_mutex);
1393         return 0;
1394 }
1395
1396 /*
1397  * Cause the rcutorture test to shutdown the system after the test has
1398  * run for the time specified by the shutdown_secs module parameter.
1399  */
1400 static int
1401 rcu_torture_shutdown(void *arg)
1402 {
1403         long delta;
1404         unsigned long jiffies_snap;
1405
1406         VERBOSE_PRINTK_STRING("rcu_torture_shutdown task started");
1407         jiffies_snap = ACCESS_ONCE(jiffies);
1408         while (ULONG_CMP_LT(jiffies_snap, shutdown_time) &&
1409                !kthread_should_stop()) {
1410                 delta = shutdown_time - jiffies_snap;
1411                 if (verbose)
1412                         printk(KERN_ALERT "%s" TORTURE_FLAG
1413                                "rcu_torture_shutdown task: %lu "
1414                                "jiffies remaining\n",
1415                                torture_type, delta);
1416                 schedule_timeout_interruptible(delta);
1417                 jiffies_snap = ACCESS_ONCE(jiffies);
1418         }
1419         if (kthread_should_stop()) {
1420                 VERBOSE_PRINTK_STRING("rcu_torture_shutdown task stopping");
1421                 return 0;
1422         }
1423
1424         /* OK, shut down the system. */
1425
1426         VERBOSE_PRINTK_STRING("rcu_torture_shutdown task shutting down system");
1427         shutdown_task = NULL;   /* Avoid self-kill deadlock. */
1428         rcu_torture_cleanup();  /* Get the success/failure message. */
1429         kernel_power_off();     /* Shut down the system. */
1430         return 0;
1431 }
1432
1433 #ifdef CONFIG_HOTPLUG_CPU
1434
1435 /*
1436  * Execute random CPU-hotplug operations at the interval specified
1437  * by the onoff_interval.
1438  */
1439 static int __cpuinit
1440 rcu_torture_onoff(void *arg)
1441 {
1442         int cpu;
1443         int maxcpu = -1;
1444         DEFINE_RCU_RANDOM(rand);
1445
1446         VERBOSE_PRINTK_STRING("rcu_torture_onoff task started");
1447         for_each_online_cpu(cpu)
1448                 maxcpu = cpu;
1449         WARN_ON(maxcpu < 0);
1450         if (onoff_holdoff > 0) {
1451                 VERBOSE_PRINTK_STRING("rcu_torture_onoff begin holdoff");
1452                 schedule_timeout_interruptible(onoff_holdoff * HZ);
1453                 VERBOSE_PRINTK_STRING("rcu_torture_onoff end holdoff");
1454         }
1455         while (!kthread_should_stop()) {
1456                 cpu = (rcu_random(&rand) >> 4) % (maxcpu + 1);
1457                 if (cpu_online(cpu) && cpu_is_hotpluggable(cpu)) {
1458                         if (verbose)
1459                                 printk(KERN_ALERT "%s" TORTURE_FLAG
1460                                        "rcu_torture_onoff task: offlining %d\n",
1461                                        torture_type, cpu);
1462                         n_offline_attempts++;
1463                         if (cpu_down(cpu) == 0) {
1464                                 if (verbose)
1465                                         printk(KERN_ALERT "%s" TORTURE_FLAG
1466                                                "rcu_torture_onoff task: "
1467                                                "offlined %d\n",
1468                                                torture_type, cpu);
1469                                 n_offline_successes++;
1470                         }
1471                 } else if (cpu_is_hotpluggable(cpu)) {
1472                         if (verbose)
1473                                 printk(KERN_ALERT "%s" TORTURE_FLAG
1474                                        "rcu_torture_onoff task: onlining %d\n",
1475                                        torture_type, cpu);
1476                         n_online_attempts++;
1477                         if (cpu_up(cpu) == 0) {
1478                                 if (verbose)
1479                                         printk(KERN_ALERT "%s" TORTURE_FLAG
1480                                                "rcu_torture_onoff task: "
1481                                                "onlined %d\n",
1482                                                torture_type, cpu);
1483                                 n_online_successes++;
1484                         }
1485                 }
1486                 schedule_timeout_interruptible(onoff_interval * HZ);
1487         }
1488         VERBOSE_PRINTK_STRING("rcu_torture_onoff task stopping");
1489         return 0;
1490 }
1491
1492 static int __cpuinit
1493 rcu_torture_onoff_init(void)
1494 {
1495         int ret;
1496
1497         if (onoff_interval <= 0)
1498                 return 0;
1499         onoff_task = kthread_run(rcu_torture_onoff, NULL, "rcu_torture_onoff");
1500         if (IS_ERR(onoff_task)) {
1501                 ret = PTR_ERR(onoff_task);
1502                 onoff_task = NULL;
1503                 return ret;
1504         }
1505         return 0;
1506 }
1507
1508 static void rcu_torture_onoff_cleanup(void)
1509 {
1510         if (onoff_task == NULL)
1511                 return;
1512         VERBOSE_PRINTK_STRING("Stopping rcu_torture_onoff task");
1513         kthread_stop(onoff_task);
1514         onoff_task = NULL;
1515 }
1516
1517 #else /* #ifdef CONFIG_HOTPLUG_CPU */
1518
1519 static int
1520 rcu_torture_onoff_init(void)
1521 {
1522         return 0;
1523 }
1524
1525 static void rcu_torture_onoff_cleanup(void)
1526 {
1527 }
1528
1529 #endif /* #else #ifdef CONFIG_HOTPLUG_CPU */
1530
1531 /*
1532  * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
1533  * induces a CPU stall for the time specified by stall_cpu.
1534  */
1535 static int __cpuinit rcu_torture_stall(void *args)
1536 {
1537         unsigned long stop_at;
1538
1539         VERBOSE_PRINTK_STRING("rcu_torture_stall task started");
1540         if (stall_cpu_holdoff > 0) {
1541                 VERBOSE_PRINTK_STRING("rcu_torture_stall begin holdoff");
1542                 schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1543                 VERBOSE_PRINTK_STRING("rcu_torture_stall end holdoff");
1544         }
1545         if (!kthread_should_stop()) {
1546                 stop_at = get_seconds() + stall_cpu;
1547                 /* RCU CPU stall is expected behavior in following code. */
1548                 printk(KERN_ALERT "rcu_torture_stall start.\n");
1549                 rcu_read_lock();
1550                 preempt_disable();
1551                 while (ULONG_CMP_LT(get_seconds(), stop_at))
1552                         continue;  /* Induce RCU CPU stall warning. */
1553                 preempt_enable();
1554                 rcu_read_unlock();
1555                 printk(KERN_ALERT "rcu_torture_stall end.\n");
1556         }
1557         rcutorture_shutdown_absorb("rcu_torture_stall");
1558         while (!kthread_should_stop())
1559                 schedule_timeout_interruptible(10 * HZ);
1560         return 0;
1561 }
1562
1563 /* Spawn CPU-stall kthread, if stall_cpu specified. */
1564 static int __init rcu_torture_stall_init(void)
1565 {
1566         int ret;
1567
1568         if (stall_cpu <= 0)
1569                 return 0;
1570         stall_task = kthread_run(rcu_torture_stall, NULL, "rcu_torture_stall");
1571         if (IS_ERR(stall_task)) {
1572                 ret = PTR_ERR(stall_task);
1573                 stall_task = NULL;
1574                 return ret;
1575         }
1576         return 0;
1577 }
1578
1579 /* Clean up after the CPU-stall kthread, if one was spawned. */
1580 static void rcu_torture_stall_cleanup(void)
1581 {
1582         if (stall_task == NULL)
1583                 return;
1584         VERBOSE_PRINTK_STRING("Stopping rcu_torture_stall_task.");
1585         kthread_stop(stall_task);
1586         stall_task = NULL;
1587 }
1588
1589 /* Callback function for RCU barrier testing. */
1590 void rcu_torture_barrier_cbf(struct rcu_head *rcu)
1591 {
1592         atomic_inc(&barrier_cbs_invoked);
1593 }
1594
1595 /* kthread function to register callbacks used to test RCU barriers. */
1596 static int rcu_torture_barrier_cbs(void *arg)
1597 {
1598         long myid = (long)arg;
1599         struct rcu_head rcu;
1600
1601         init_rcu_head_on_stack(&rcu);
1602         VERBOSE_PRINTK_STRING("rcu_torture_barrier_cbs task started");
1603         set_user_nice(current, 19);
1604         do {
1605                 wait_event(barrier_cbs_wq[myid],
1606                            atomic_read(&barrier_cbs_count) == n_barrier_cbs ||
1607                            kthread_should_stop() ||
1608                            fullstop != FULLSTOP_DONTSTOP);
1609                 if (kthread_should_stop() || fullstop != FULLSTOP_DONTSTOP)
1610                         break;
1611                 cur_ops->call(&rcu, rcu_torture_barrier_cbf);
1612                 if (atomic_dec_and_test(&barrier_cbs_count))
1613                         wake_up(&barrier_wq);
1614         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1615         VERBOSE_PRINTK_STRING("rcu_torture_barrier_cbs task stopping");
1616         rcutorture_shutdown_absorb("rcu_torture_barrier_cbs");
1617         while (!kthread_should_stop())
1618                 schedule_timeout_interruptible(1);
1619         cur_ops->cb_barrier();
1620         destroy_rcu_head_on_stack(&rcu);
1621         return 0;
1622 }
1623
1624 /* kthread function to drive and coordinate RCU barrier testing. */
1625 static int rcu_torture_barrier(void *arg)
1626 {
1627         int i;
1628
1629         VERBOSE_PRINTK_STRING("rcu_torture_barrier task starting");
1630         do {
1631                 atomic_set(&barrier_cbs_invoked, 0);
1632                 atomic_set(&barrier_cbs_count, n_barrier_cbs);
1633                 /* wake_up() path contains the required barriers. */
1634                 for (i = 0; i < n_barrier_cbs; i++)
1635                         wake_up(&barrier_cbs_wq[i]);
1636                 wait_event(barrier_wq,
1637                            atomic_read(&barrier_cbs_count) == 0 ||
1638                            kthread_should_stop() ||
1639                            fullstop != FULLSTOP_DONTSTOP);
1640                 if (kthread_should_stop() || fullstop != FULLSTOP_DONTSTOP)
1641                         break;
1642                 n_barrier_attempts++;
1643                 cur_ops->cb_barrier();
1644                 if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
1645                         n_rcu_torture_barrier_error++;
1646                         WARN_ON_ONCE(1);
1647                 }
1648                 n_barrier_successes++;
1649                 schedule_timeout_interruptible(HZ / 10);
1650         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1651         VERBOSE_PRINTK_STRING("rcu_torture_barrier task stopping");
1652         rcutorture_shutdown_absorb("rcu_torture_barrier_cbs");
1653         while (!kthread_should_stop())
1654                 schedule_timeout_interruptible(1);
1655         return 0;
1656 }
1657
1658 /* Initialize RCU barrier testing. */
1659 static int rcu_torture_barrier_init(void)
1660 {
1661         int i;
1662         int ret;
1663
1664         if (n_barrier_cbs == 0)
1665                 return 0;
1666         if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
1667                 printk(KERN_ALERT "%s" TORTURE_FLAG
1668                        " Call or barrier ops missing for %s,\n",
1669                        torture_type, cur_ops->name);
1670                 printk(KERN_ALERT "%s" TORTURE_FLAG
1671                        " RCU barrier testing omitted from run.\n",
1672                        torture_type);
1673                 return 0;
1674         }
1675         atomic_set(&barrier_cbs_count, 0);
1676         atomic_set(&barrier_cbs_invoked, 0);
1677         barrier_cbs_tasks =
1678                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_tasks[0]),
1679                         GFP_KERNEL);
1680         barrier_cbs_wq =
1681                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_wq[0]),
1682                         GFP_KERNEL);
1683         if (barrier_cbs_tasks == NULL || barrier_cbs_wq == 0)
1684                 return -ENOMEM;
1685         for (i = 0; i < n_barrier_cbs; i++) {
1686                 init_waitqueue_head(&barrier_cbs_wq[i]);
1687                 barrier_cbs_tasks[i] = kthread_run(rcu_torture_barrier_cbs,
1688                                                    (void *)i,
1689                                                    "rcu_torture_barrier_cbs");
1690                 if (IS_ERR(barrier_cbs_tasks[i])) {
1691                         ret = PTR_ERR(barrier_cbs_tasks[i]);
1692                         VERBOSE_PRINTK_ERRSTRING("Failed to create rcu_torture_barrier_cbs");
1693                         barrier_cbs_tasks[i] = NULL;
1694                         return ret;
1695                 }
1696         }
1697         barrier_task = kthread_run(rcu_torture_barrier, NULL,
1698                                    "rcu_torture_barrier");
1699         if (IS_ERR(barrier_task)) {
1700                 ret = PTR_ERR(barrier_task);
1701                 VERBOSE_PRINTK_ERRSTRING("Failed to create rcu_torture_barrier");
1702                 barrier_task = NULL;
1703         }
1704         return 0;
1705 }
1706
1707 /* Clean up after RCU barrier testing. */
1708 static void rcu_torture_barrier_cleanup(void)
1709 {
1710         int i;
1711
1712         if (barrier_task != NULL) {
1713                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_barrier task");
1714                 kthread_stop(barrier_task);
1715                 barrier_task = NULL;
1716         }
1717         if (barrier_cbs_tasks != NULL) {
1718                 for (i = 0; i < n_barrier_cbs; i++) {
1719                         if (barrier_cbs_tasks[i] != NULL) {
1720                                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_barrier_cbs task");
1721                                 kthread_stop(barrier_cbs_tasks[i]);
1722                                 barrier_cbs_tasks[i] = NULL;
1723                         }
1724                 }
1725                 kfree(barrier_cbs_tasks);
1726                 barrier_cbs_tasks = NULL;
1727         }
1728         if (barrier_cbs_wq != NULL) {
1729                 kfree(barrier_cbs_wq);
1730                 barrier_cbs_wq = NULL;
1731         }
1732 }
1733
1734 static int rcutorture_cpu_notify(struct notifier_block *self,
1735                                  unsigned long action, void *hcpu)
1736 {
1737         long cpu = (long)hcpu;
1738
1739         switch (action) {
1740         case CPU_ONLINE:
1741         case CPU_DOWN_FAILED:
1742                 (void)rcutorture_booster_init(cpu);
1743                 break;
1744         case CPU_DOWN_PREPARE:
1745                 rcutorture_booster_cleanup(cpu);
1746                 break;
1747         default:
1748                 break;
1749         }
1750         return NOTIFY_OK;
1751 }
1752
1753 static struct notifier_block rcutorture_cpu_nb = {
1754         .notifier_call = rcutorture_cpu_notify,
1755 };
1756
1757 static void
1758 rcu_torture_cleanup(void)
1759 {
1760         int i;
1761
1762         mutex_lock(&fullstop_mutex);
1763         rcutorture_record_test_transition();
1764         if (fullstop == FULLSTOP_SHUTDOWN) {
1765                 printk(KERN_WARNING /* but going down anyway, so... */
1766                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
1767                 mutex_unlock(&fullstop_mutex);
1768                 schedule_timeout_uninterruptible(10);
1769                 if (cur_ops->cb_barrier != NULL)
1770                         cur_ops->cb_barrier();
1771                 return;
1772         }
1773         fullstop = FULLSTOP_RMMOD;
1774         mutex_unlock(&fullstop_mutex);
1775         unregister_reboot_notifier(&rcutorture_shutdown_nb);
1776         rcu_torture_barrier_cleanup();
1777         rcu_torture_stall_cleanup();
1778         if (stutter_task) {
1779                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
1780                 kthread_stop(stutter_task);
1781         }
1782         stutter_task = NULL;
1783         if (shuffler_task) {
1784                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
1785                 kthread_stop(shuffler_task);
1786                 free_cpumask_var(shuffle_tmp_mask);
1787         }
1788         shuffler_task = NULL;
1789
1790         if (writer_task) {
1791                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
1792                 kthread_stop(writer_task);
1793         }
1794         writer_task = NULL;
1795
1796         if (reader_tasks) {
1797                 for (i = 0; i < nrealreaders; i++) {
1798                         if (reader_tasks[i]) {
1799                                 VERBOSE_PRINTK_STRING(
1800                                         "Stopping rcu_torture_reader task");
1801                                 kthread_stop(reader_tasks[i]);
1802                         }
1803                         reader_tasks[i] = NULL;
1804                 }
1805                 kfree(reader_tasks);
1806                 reader_tasks = NULL;
1807         }
1808         rcu_torture_current = NULL;
1809
1810         if (fakewriter_tasks) {
1811                 for (i = 0; i < nfakewriters; i++) {
1812                         if (fakewriter_tasks[i]) {
1813                                 VERBOSE_PRINTK_STRING(
1814                                         "Stopping rcu_torture_fakewriter task");
1815                                 kthread_stop(fakewriter_tasks[i]);
1816                         }
1817                         fakewriter_tasks[i] = NULL;
1818                 }
1819                 kfree(fakewriter_tasks);
1820                 fakewriter_tasks = NULL;
1821         }
1822
1823         if (stats_task) {
1824                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
1825                 kthread_stop(stats_task);
1826         }
1827         stats_task = NULL;
1828
1829         if (fqs_task) {
1830                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_fqs task");
1831                 kthread_stop(fqs_task);
1832         }
1833         fqs_task = NULL;
1834         if ((test_boost == 1 && cur_ops->can_boost) ||
1835             test_boost == 2) {
1836                 unregister_cpu_notifier(&rcutorture_cpu_nb);
1837                 for_each_possible_cpu(i)
1838                         rcutorture_booster_cleanup(i);
1839         }
1840         if (shutdown_task != NULL) {
1841                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shutdown task");
1842                 kthread_stop(shutdown_task);
1843         }
1844         shutdown_task = NULL;
1845         rcu_torture_onoff_cleanup();
1846
1847         /* Wait for all RCU callbacks to fire.  */
1848
1849         if (cur_ops->cb_barrier != NULL)
1850                 cur_ops->cb_barrier();
1851
1852         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1853
1854         if (cur_ops->cleanup)
1855                 cur_ops->cleanup();
1856         if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
1857                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1858         else if (n_online_successes != n_online_attempts ||
1859                  n_offline_successes != n_offline_attempts)
1860                 rcu_torture_print_module_parms(cur_ops,
1861                                                "End of test: RCU_HOTPLUG");
1862         else
1863                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1864 }
1865
1866 static int __init
1867 rcu_torture_init(void)
1868 {
1869         int i;
1870         int cpu;
1871         int firsterr = 0;
1872         int retval;
1873         static struct rcu_torture_ops *torture_ops[] =
1874                 { &rcu_ops, &rcu_sync_ops, &rcu_expedited_ops,
1875                   &rcu_bh_ops, &rcu_bh_sync_ops, &rcu_bh_expedited_ops,
1876                   &srcu_ops, &srcu_raw_ops, &srcu_expedited_ops,
1877                   &sched_ops, &sched_sync_ops, &sched_expedited_ops, };
1878
1879         mutex_lock(&fullstop_mutex);
1880
1881         /* Process args and tell the world that the torturer is on the job. */
1882         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1883                 cur_ops = torture_ops[i];
1884                 if (strcmp(torture_type, cur_ops->name) == 0)
1885                         break;
1886         }
1887         if (i == ARRAY_SIZE(torture_ops)) {
1888                 printk(KERN_ALERT "rcu-torture: invalid torture type: \"%s\"\n",
1889                        torture_type);
1890                 printk(KERN_ALERT "rcu-torture types:");
1891                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1892                         printk(KERN_ALERT " %s", torture_ops[i]->name);
1893                 printk(KERN_ALERT "\n");
1894                 mutex_unlock(&fullstop_mutex);
1895                 return -EINVAL;
1896         }
1897         if (cur_ops->fqs == NULL && fqs_duration != 0) {
1898                 printk(KERN_ALERT "rcu-torture: ->fqs NULL and non-zero "
1899                                   "fqs_duration, fqs disabled.\n");
1900                 fqs_duration = 0;
1901         }
1902         if (cur_ops->init)
1903                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1904
1905         if (nreaders >= 0)
1906                 nrealreaders = nreaders;
1907         else
1908                 nrealreaders = 2 * num_online_cpus();
1909         rcu_torture_print_module_parms(cur_ops, "Start of test");
1910         fullstop = FULLSTOP_DONTSTOP;
1911
1912         /* Set up the freelist. */
1913
1914         INIT_LIST_HEAD(&rcu_torture_freelist);
1915         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1916                 rcu_tortures[i].rtort_mbtest = 0;
1917                 list_add_tail(&rcu_tortures[i].rtort_free,
1918                               &rcu_torture_freelist);
1919         }
1920
1921         /* Initialize the statistics so that each run gets its own numbers. */
1922
1923         rcu_torture_current = NULL;
1924         rcu_torture_current_version = 0;
1925         atomic_set(&n_rcu_torture_alloc, 0);
1926         atomic_set(&n_rcu_torture_alloc_fail, 0);
1927         atomic_set(&n_rcu_torture_free, 0);
1928         atomic_set(&n_rcu_torture_mberror, 0);
1929         atomic_set(&n_rcu_torture_error, 0);
1930         n_rcu_torture_barrier_error = 0;
1931         n_rcu_torture_boost_ktrerror = 0;
1932         n_rcu_torture_boost_rterror = 0;
1933         n_rcu_torture_boost_failure = 0;
1934         n_rcu_torture_boosts = 0;
1935         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1936                 atomic_set(&rcu_torture_wcount[i], 0);
1937         for_each_possible_cpu(cpu) {
1938                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1939                         per_cpu(rcu_torture_count, cpu)[i] = 0;
1940                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
1941                 }
1942         }
1943
1944         /* Start up the kthreads. */
1945
1946         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
1947         writer_task = kthread_run(rcu_torture_writer, NULL,
1948                                   "rcu_torture_writer");
1949         if (IS_ERR(writer_task)) {
1950                 firsterr = PTR_ERR(writer_task);
1951                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
1952                 writer_task = NULL;
1953                 goto unwind;
1954         }
1955         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1956                                    GFP_KERNEL);
1957         if (fakewriter_tasks == NULL) {
1958                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1959                 firsterr = -ENOMEM;
1960                 goto unwind;
1961         }
1962         for (i = 0; i < nfakewriters; i++) {
1963                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
1964                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
1965                                                   "rcu_torture_fakewriter");
1966                 if (IS_ERR(fakewriter_tasks[i])) {
1967                         firsterr = PTR_ERR(fakewriter_tasks[i]);
1968                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
1969                         fakewriter_tasks[i] = NULL;
1970                         goto unwind;
1971                 }
1972         }
1973         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1974                                GFP_KERNEL);
1975         if (reader_tasks == NULL) {
1976                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1977                 firsterr = -ENOMEM;
1978                 goto unwind;
1979         }
1980         for (i = 0; i < nrealreaders; i++) {
1981                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
1982                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
1983                                               "rcu_torture_reader");
1984                 if (IS_ERR(reader_tasks[i])) {
1985                         firsterr = PTR_ERR(reader_tasks[i]);
1986                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
1987                         reader_tasks[i] = NULL;
1988                         goto unwind;
1989                 }
1990         }
1991         if (stat_interval > 0) {
1992                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
1993                 stats_task = kthread_run(rcu_torture_stats, NULL,
1994                                         "rcu_torture_stats");
1995                 if (IS_ERR(stats_task)) {
1996                         firsterr = PTR_ERR(stats_task);
1997                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
1998                         stats_task = NULL;
1999                         goto unwind;
2000                 }
2001         }
2002         if (test_no_idle_hz) {
2003                 rcu_idle_cpu = num_online_cpus() - 1;
2004
2005                 if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
2006                         firsterr = -ENOMEM;
2007                         VERBOSE_PRINTK_ERRSTRING("Failed to alloc mask");
2008                         goto unwind;
2009                 }
2010
2011                 /* Create the shuffler thread */
2012                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
2013                                           "rcu_torture_shuffle");
2014                 if (IS_ERR(shuffler_task)) {
2015                         free_cpumask_var(shuffle_tmp_mask);
2016                         firsterr = PTR_ERR(shuffler_task);
2017                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
2018                         shuffler_task = NULL;
2019                         goto unwind;
2020                 }
2021         }
2022         if (stutter < 0)
2023                 stutter = 0;
2024         if (stutter) {
2025                 /* Create the stutter thread */
2026                 stutter_task = kthread_run(rcu_torture_stutter, NULL,
2027                                           "rcu_torture_stutter");
2028                 if (IS_ERR(stutter_task)) {
2029                         firsterr = PTR_ERR(stutter_task);
2030                         VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
2031                         stutter_task = NULL;
2032                         goto unwind;
2033                 }
2034         }
2035         if (fqs_duration < 0)
2036                 fqs_duration = 0;
2037         if (fqs_duration) {
2038                 /* Create the stutter thread */
2039                 fqs_task = kthread_run(rcu_torture_fqs, NULL,
2040                                        "rcu_torture_fqs");
2041                 if (IS_ERR(fqs_task)) {
2042                         firsterr = PTR_ERR(fqs_task);
2043                         VERBOSE_PRINTK_ERRSTRING("Failed to create fqs");
2044                         fqs_task = NULL;
2045                         goto unwind;
2046                 }
2047         }
2048         if (test_boost_interval < 1)
2049                 test_boost_interval = 1;
2050         if (test_boost_duration < 2)
2051                 test_boost_duration = 2;
2052         if ((test_boost == 1 && cur_ops->can_boost) ||
2053             test_boost == 2) {
2054
2055                 boost_starttime = jiffies + test_boost_interval * HZ;
2056                 register_cpu_notifier(&rcutorture_cpu_nb);
2057                 for_each_possible_cpu(i) {
2058                         if (cpu_is_offline(i))
2059                                 continue;  /* Heuristic: CPU can go offline. */
2060                         retval = rcutorture_booster_init(i);
2061                         if (retval < 0) {
2062                                 firsterr = retval;
2063                                 goto unwind;
2064                         }
2065                 }
2066         }
2067         if (shutdown_secs > 0) {
2068                 shutdown_time = jiffies + shutdown_secs * HZ;
2069                 shutdown_task = kthread_run(rcu_torture_shutdown, NULL,
2070                                             "rcu_torture_shutdown");
2071                 if (IS_ERR(shutdown_task)) {
2072                         firsterr = PTR_ERR(shutdown_task);
2073                         VERBOSE_PRINTK_ERRSTRING("Failed to create shutdown");
2074                         shutdown_task = NULL;
2075                         goto unwind;
2076                 }
2077         }
2078         i = rcu_torture_onoff_init();
2079         if (i != 0) {
2080                 firsterr = i;
2081                 goto unwind;
2082         }
2083         register_reboot_notifier(&rcutorture_shutdown_nb);
2084         i = rcu_torture_stall_init();
2085         if (i != 0) {
2086                 firsterr = i;
2087                 goto unwind;
2088         }
2089         retval = rcu_torture_barrier_init();
2090         if (retval != 0) {
2091                 firsterr = retval;
2092                 goto unwind;
2093         }
2094         rcutorture_record_test_transition();
2095         mutex_unlock(&fullstop_mutex);
2096         return 0;
2097
2098 unwind:
2099         mutex_unlock(&fullstop_mutex);
2100         rcu_torture_cleanup();
2101         return firsterr;
2102 }
2103
2104 module_init(rcu_torture_init);
2105 module_exit(rcu_torture_cleanup);