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 Josh Triplett <josh@freedesktop.org>");
  53
  54 static int nreaders = -1;       /* # reader threads, defaults to 2*ncpus */
  55 static int nfakewriters = 4;    /* # fake writer threads */
  56 static int stat_interval = 60;  /* Interval between stats, in seconds. */
  57                                 /*  Zero means "only at end of test". */
  58 static bool verbose;            /* Print more debug info. */
  59 static bool test_no_idle_hz = true;
  60                                 /* Test RCU 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 { pr_alert("%s" TORTURE_FLAG s "\n", torture_type); } while (0)
 124 #define VERBOSE_PRINTK_STRING(s) \
 125         do { if (verbose) pr_alert("%s" TORTURE_FLAG s "\n", torture_type); } while (0)
 126 #define VERBOSE_PRINTK_ERRSTRING(s) \
 127         do { if (verbose) pr_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 unsigned long sum_offline;
 181 static int min_offline = -1;
 182 static int max_offline;
 183 static long n_online_attempts;
 184 static long n_online_successes;
 185 static unsigned long sum_online;
 186 static int min_online = -1;
 187 static int max_online;
 188 static long n_barrier_attempts;
 189 static long n_barrier_successes;
 190 static struct list_head rcu_torture_removed;
 191 static cpumask_var_t shuffle_tmp_mask;
 192
 193 static int stutter_pause_test;
 194
 195 #if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
 196 #define RCUTORTURE_RUNNABLE_INIT 1
 197 #else
 198 #define RCUTORTURE_RUNNABLE_INIT 0
 199 #endif
 200 int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT;
 201 module_param(rcutorture_runnable, int, 0444);
 202 MODULE_PARM_DESC(rcutorture_runnable, "Start rcutorture at boot");
 203
 204 #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
 205 #define rcu_can_boost() 1
 206 #else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 207 #define rcu_can_boost() 0
 208 #endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 209
 210 static unsigned long shutdown_time;     /* jiffies to system shutdown. */
 211 static unsigned long boost_starttime;   /* jiffies of next boost test start. */
 212 DEFINE_MUTEX(boost_mutex);              /* protect setting boost_starttime */
 213                                         /*  and boost task create/destroy. */
 214 static atomic_t barrier_cbs_count;      /* Barrier callbacks registered. */
 215 static bool barrier_phase;              /* Test phase. */
 216 static atomic_t barrier_cbs_invoked;    /* Barrier callbacks invoked. */
 217 static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */
 218 static DECLARE_WAIT_QUEUE_HEAD(barrier_wq);
 219
 220 /* Mediate rmmod and system shutdown.  Concurrent rmmod & shutdown illegal! */
 221
 222 #define FULLSTOP_DONTSTOP 0     /* Normal operation. */
 223 #define FULLSTOP_SHUTDOWN 1     /* System shutdown with rcutorture running. */
 224 #define FULLSTOP_RMMOD    2     /* Normal rmmod of rcutorture. */
 225 static int fullstop = FULLSTOP_RMMOD;
 226 /*
 227  * Protect fullstop transitions and spawning of kthreads.
 228  */
 229 static DEFINE_MUTEX(fullstop_mutex);
 230
 231 /* Forward reference. */
 232 static void rcu_torture_cleanup(void);
 233
 234 /*
 235  * Detect and respond to a system shutdown.
 236  */
 237 static int
 238 rcutorture_shutdown_notify(struct notifier_block *unused1,
 239                            unsigned long unused2, void *unused3)
 240 {
 241         mutex_lock(&fullstop_mutex);
 242         if (fullstop == FULLSTOP_DONTSTOP)
 243                 fullstop = FULLSTOP_SHUTDOWN;
 244         else
 245                 pr_warn(/* but going down anyway, so... */
 246                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
 247         mutex_unlock(&fullstop_mutex);
 248         return NOTIFY_DONE;
 249 }
 250
 251 /*
 252  * Absorb kthreads into a kernel function that won't return, so that
 253  * they won't ever access module text or data again.
 254  */
 255 static void rcutorture_shutdown_absorb(char *title)
 256 {
 257         if (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
 258                 pr_notice(
 259                        "rcutorture thread %s parking due to system shutdown\n",
 260                        title);
 261                 schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
 262         }
 263 }
 264
 265 /*
 266  * Allocate an element from the rcu_tortures pool.
 267  */
 268 static struct rcu_torture *
 269 rcu_torture_alloc(void)
 270 {
 271         struct list_head *p;
 272
 273         spin_lock_bh(&rcu_torture_lock);
 274         if (list_empty(&rcu_torture_freelist)) {
 275                 atomic_inc(&n_rcu_torture_alloc_fail);
 276                 spin_unlock_bh(&rcu_torture_lock);
 277                 return NULL;
 278         }
 279         atomic_inc(&n_rcu_torture_alloc);
 280         p = rcu_torture_freelist.next;
 281         list_del_init(p);
 282         spin_unlock_bh(&rcu_torture_lock);
 283         return container_of(p, struct rcu_torture, rtort_free);
 284 }
 285
 286 /*
 287  * Free an element to the rcu_tortures pool.
 288  */
 289 static void
 290 rcu_torture_free(struct rcu_torture *p)
 291 {
 292         atomic_inc(&n_rcu_torture_free);
 293         spin_lock_bh(&rcu_torture_lock);
 294         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 295         spin_unlock_bh(&rcu_torture_lock);
 296 }
 297
 298 struct rcu_random_state {
 299         unsigned long rrs_state;
 300         long rrs_count;
 301 };
 302
 303 #define RCU_RANDOM_MULT 39916801  /* prime */
 304 #define RCU_RANDOM_ADD  479001701 /* prime */
 305 #define RCU_RANDOM_REFRESH 10000
 306
 307 #define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
 308
 309 /*
 310  * Crude but fast random-number generator.  Uses a linear congruential
 311  * generator, with occasional help from cpu_clock().
 312  */
 313 static unsigned long
 314 rcu_random(struct rcu_random_state *rrsp)
 315 {
 316         if (--rrsp->rrs_count < 0) {
 317                 rrsp->rrs_state += (unsigned long)local_clock();
 318                 rrsp->rrs_count = RCU_RANDOM_REFRESH;
 319         }
 320         rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
 321         return swahw32(rrsp->rrs_state);
 322 }
 323
 324 static void
 325 rcu_stutter_wait(char *title)
 326 {
 327         while (stutter_pause_test || !rcutorture_runnable) {
 328                 if (rcutorture_runnable)
 329                         schedule_timeout_interruptible(1);
 330                 else
 331                         schedule_timeout_interruptible(round_jiffies_relative(HZ));
 332                 rcutorture_shutdown_absorb(title);
 333         }
 334 }
 335
 336 /*
 337  * Operations vector for selecting different types of tests.
 338  */
 339
 340 struct rcu_torture_ops {
 341         void (*init)(void);
 342         int (*readlock)(void);
 343         void (*read_delay)(struct rcu_random_state *rrsp);
 344         void (*readunlock)(int idx);
 345         int (*completed)(void);
 346         void (*deferred_free)(struct rcu_torture *p);
 347         void (*sync)(void);
 348         void (*call)(struct rcu_head *head, void (*func)(struct rcu_head *rcu));
 349         void (*cb_barrier)(void);
 350         void (*fqs)(void);
 351         int (*stats)(char *page);
 352         int irq_capable;
 353         int can_boost;
 354         char *name;
 355 };
 356
 357 static struct rcu_torture_ops *cur_ops;
 358
 359 /*
 360  * Definitions for rcu torture testing.
 361  */
 362
 363 static int rcu_torture_read_lock(void) __acquires(RCU)
 364 {
 365         rcu_read_lock();
 366         return 0;
 367 }
 368
 369 static void rcu_read_delay(struct rcu_random_state *rrsp)
 370 {
 371         const unsigned long shortdelay_us = 200;
 372         const unsigned long longdelay_ms = 50;
 373
 374         /* We want a short delay sometimes to make a reader delay the grace
 375          * period, and we want a long delay occasionally to trigger
 376          * force_quiescent_state. */
 377
 378         if (!(rcu_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
 379                 mdelay(longdelay_ms);
 380         if (!(rcu_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
 381                 udelay(shortdelay_us);
 382 #ifdef CONFIG_PREEMPT
 383         if (!preempt_count() && !(rcu_random(rrsp) % (nrealreaders * 20000)))
 384                 preempt_schedule();  /* No QS if preempt_disable() in effect */
 385 #endif
 386 }
 387
 388 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 389 {
 390         rcu_read_unlock();
 391 }
 392
 393 static int rcu_torture_completed(void)
 394 {
 395         return rcu_batches_completed();
 396 }
 397
 398 static void
 399 rcu_torture_cb(struct rcu_head *p)
 400 {
 401         int i;
 402         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 403
 404         if (fullstop != FULLSTOP_DONTSTOP) {
 405                 /* Test is ending, just drop callbacks on the floor. */
 406                 /* The next initialization will pick up the pieces. */
 407                 return;
 408         }
 409         i = rp->rtort_pipe_count;
 410         if (i > RCU_TORTURE_PIPE_LEN)
 411                 i = RCU_TORTURE_PIPE_LEN;
 412         atomic_inc(&rcu_torture_wcount[i]);
 413         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 414                 rp->rtort_mbtest = 0;
 415                 rcu_torture_free(rp);
 416         } else {
 417                 cur_ops->deferred_free(rp);
 418         }
 419 }
 420
 421 static int rcu_no_completed(void)
 422 {
 423         return 0;
 424 }
 425
 426 static void rcu_torture_deferred_free(struct rcu_torture *p)
 427 {
 428         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 429 }
 430
 431 static struct rcu_torture_ops rcu_ops = {
 432         .init           = NULL,
 433         .readlock       = rcu_torture_read_lock,
 434         .read_delay     = rcu_read_delay,
 435         .readunlock     = rcu_torture_read_unlock,
 436         .completed      = rcu_torture_completed,
 437         .deferred_free  = rcu_torture_deferred_free,
 438         .sync           = synchronize_rcu,
 439         .call           = call_rcu,
 440         .cb_barrier     = rcu_barrier,
 441         .fqs            = rcu_force_quiescent_state,
 442         .stats          = NULL,
 443         .irq_capable    = 1,
 444         .can_boost      = rcu_can_boost(),
 445         .name           = "rcu"
 446 };
 447
 448 static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
 449 {
 450         int i;
 451         struct rcu_torture *rp;
 452         struct rcu_torture *rp1;
 453
 454         cur_ops->sync();
 455         list_add(&p->rtort_free, &rcu_torture_removed);
 456         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 457                 i = rp->rtort_pipe_count;
 458                 if (i > RCU_TORTURE_PIPE_LEN)
 459                         i = RCU_TORTURE_PIPE_LEN;
 460                 atomic_inc(&rcu_torture_wcount[i]);
 461                 if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 462                         rp->rtort_mbtest = 0;
 463                         list_del(&rp->rtort_free);
 464                         rcu_torture_free(rp);
 465                 }
 466         }
 467 }
 468
 469 static void rcu_sync_torture_init(void)
 470 {
 471         INIT_LIST_HEAD(&rcu_torture_removed);
 472 }
 473
 474 static struct rcu_torture_ops rcu_sync_ops = {
 475         .init           = rcu_sync_torture_init,
 476         .readlock       = rcu_torture_read_lock,
 477         .read_delay     = rcu_read_delay,
 478         .readunlock     = rcu_torture_read_unlock,
 479         .completed      = rcu_torture_completed,
 480         .deferred_free  = rcu_sync_torture_deferred_free,
 481         .sync           = synchronize_rcu,
 482         .call           = NULL,
 483         .cb_barrier     = NULL,
 484         .fqs            = rcu_force_quiescent_state,
 485         .stats          = NULL,
 486         .irq_capable    = 1,
 487         .can_boost      = rcu_can_boost(),
 488         .name           = "rcu_sync"
 489 };
 490
 491 static struct rcu_torture_ops rcu_expedited_ops = {
 492         .init           = rcu_sync_torture_init,
 493         .readlock       = rcu_torture_read_lock,
 494         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 495         .readunlock     = rcu_torture_read_unlock,
 496         .completed      = rcu_no_completed,
 497         .deferred_free  = rcu_sync_torture_deferred_free,
 498         .sync           = synchronize_rcu_expedited,
 499         .call           = NULL,
 500         .cb_barrier     = NULL,
 501         .fqs            = rcu_force_quiescent_state,
 502         .stats          = NULL,
 503         .irq_capable    = 1,
 504         .can_boost      = rcu_can_boost(),
 505         .name           = "rcu_expedited"
 506 };
 507
 508 /*
 509  * Definitions for rcu_bh torture testing.
 510  */
 511
 512 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
 513 {
 514         rcu_read_lock_bh();
 515         return 0;
 516 }
 517
 518 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
 519 {
 520         rcu_read_unlock_bh();
 521 }
 522
 523 static int rcu_bh_torture_completed(void)
 524 {
 525         return rcu_batches_completed_bh();
 526 }
 527
 528 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 529 {
 530         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
 531 }
 532
 533 static struct rcu_torture_ops rcu_bh_ops = {
 534         .init           = NULL,
 535         .readlock       = rcu_bh_torture_read_lock,
 536         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 537         .readunlock     = rcu_bh_torture_read_unlock,
 538         .completed      = rcu_bh_torture_completed,
 539         .deferred_free  = rcu_bh_torture_deferred_free,
 540         .sync           = synchronize_rcu_bh,
 541         .call           = call_rcu_bh,
 542         .cb_barrier     = rcu_barrier_bh,
 543         .fqs            = rcu_bh_force_quiescent_state,
 544         .stats          = NULL,
 545         .irq_capable    = 1,
 546         .name           = "rcu_bh"
 547 };
 548
 549 static struct rcu_torture_ops rcu_bh_sync_ops = {
 550         .init           = rcu_sync_torture_init,
 551         .readlock       = rcu_bh_torture_read_lock,
 552         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 553         .readunlock     = rcu_bh_torture_read_unlock,
 554         .completed      = rcu_bh_torture_completed,
 555         .deferred_free  = rcu_sync_torture_deferred_free,
 556         .sync           = synchronize_rcu_bh,
 557         .call           = NULL,
 558         .cb_barrier     = NULL,
 559         .fqs            = rcu_bh_force_quiescent_state,
 560         .stats          = NULL,
 561         .irq_capable    = 1,
 562         .name           = "rcu_bh_sync"
 563 };
 564
 565 static struct rcu_torture_ops rcu_bh_expedited_ops = {
 566         .init           = rcu_sync_torture_init,
 567         .readlock       = rcu_bh_torture_read_lock,
 568         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 569         .readunlock     = rcu_bh_torture_read_unlock,
 570         .completed      = rcu_bh_torture_completed,
 571         .deferred_free  = rcu_sync_torture_deferred_free,
 572         .sync           = synchronize_rcu_bh_expedited,
 573         .call           = NULL,
 574         .cb_barrier     = NULL,
 575         .fqs            = rcu_bh_force_quiescent_state,
 576         .stats          = NULL,
 577         .irq_capable    = 1,
 578         .name           = "rcu_bh_expedited"
 579 };
 580
 581 /*
 582  * Definitions for srcu torture testing.
 583  */
 584
 585 DEFINE_STATIC_SRCU(srcu_ctl);
 586
 587 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
 588 {
 589         return srcu_read_lock(&srcu_ctl);
 590 }
 591
 592 static void srcu_read_delay(struct rcu_random_state *rrsp)
 593 {
 594         long delay;
 595         const long uspertick = 1000000 / HZ;
 596         const long longdelay = 10;
 597
 598         /* We want there to be long-running readers, but not all the time. */
 599
 600         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
 601         if (!delay)
 602                 schedule_timeout_interruptible(longdelay);
 603         else
 604                 rcu_read_delay(rrsp);
 605 }
 606
 607 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
 608 {
 609         srcu_read_unlock(&srcu_ctl, idx);
 610 }
 611
 612 static int srcu_torture_completed(void)
 613 {
 614         return srcu_batches_completed(&srcu_ctl);
 615 }
 616
 617 static void srcu_torture_deferred_free(struct rcu_torture *rp)
 618 {
 619         call_srcu(&srcu_ctl, &rp->rtort_rcu, rcu_torture_cb);
 620 }
 621
 622 static void srcu_torture_synchronize(void)
 623 {
 624         synchronize_srcu(&srcu_ctl);
 625 }
 626
 627 static void srcu_torture_call(struct rcu_head *head,
 628                               void (*func)(struct rcu_head *head))
 629 {
 630         call_srcu(&srcu_ctl, head, func);
 631 }
 632
 633 static void srcu_torture_barrier(void)
 634 {
 635         srcu_barrier(&srcu_ctl);
 636 }
 637
 638 static int srcu_torture_stats(char *page)
 639 {
 640         int cnt = 0;
 641         int cpu;
 642         int idx = srcu_ctl.completed & 0x1;
 643
 644         cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
 645                        torture_type, TORTURE_FLAG, idx);
 646         for_each_possible_cpu(cpu) {
 647                 cnt += sprintf(&page[cnt], " %d(%lu,%lu)", cpu,
 648                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
 649                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
 650         }
 651         cnt += sprintf(&page[cnt], "\n");
 652         return cnt;
 653 }
 654
 655 static struct rcu_torture_ops srcu_ops = {
 656         .init           = rcu_sync_torture_init,
 657         .readlock       = srcu_torture_read_lock,
 658         .read_delay     = srcu_read_delay,
 659         .readunlock     = srcu_torture_read_unlock,
 660         .completed      = srcu_torture_completed,
 661         .deferred_free  = srcu_torture_deferred_free,
 662         .sync           = srcu_torture_synchronize,
 663         .call           = srcu_torture_call,
 664         .cb_barrier     = srcu_torture_barrier,
 665         .stats          = srcu_torture_stats,
 666         .name           = "srcu"
 667 };
 668
 669 static struct rcu_torture_ops srcu_sync_ops = {
 670         .init           = rcu_sync_torture_init,
 671         .readlock       = srcu_torture_read_lock,
 672         .read_delay     = srcu_read_delay,
 673         .readunlock     = srcu_torture_read_unlock,
 674         .completed      = srcu_torture_completed,
 675         .deferred_free  = rcu_sync_torture_deferred_free,
 676         .sync           = srcu_torture_synchronize,
 677         .call           = NULL,
 678         .cb_barrier     = NULL,
 679         .stats          = srcu_torture_stats,
 680         .name           = "srcu_sync"
 681 };
 682
 683 static int srcu_torture_read_lock_raw(void) __acquires(&srcu_ctl)
 684 {
 685         return srcu_read_lock_raw(&srcu_ctl);
 686 }
 687
 688 static void srcu_torture_read_unlock_raw(int idx) __releases(&srcu_ctl)
 689 {
 690         srcu_read_unlock_raw(&srcu_ctl, idx);
 691 }
 692
 693 static struct rcu_torture_ops srcu_raw_ops = {
 694         .init           = rcu_sync_torture_init,
 695         .readlock       = srcu_torture_read_lock_raw,
 696         .read_delay     = srcu_read_delay,
 697         .readunlock     = srcu_torture_read_unlock_raw,
 698         .completed      = srcu_torture_completed,
 699         .deferred_free  = srcu_torture_deferred_free,
 700         .sync           = srcu_torture_synchronize,
 701         .call           = NULL,
 702         .cb_barrier     = NULL,
 703         .stats          = srcu_torture_stats,
 704         .name           = "srcu_raw"
 705 };
 706
 707 static struct rcu_torture_ops srcu_raw_sync_ops = {
 708         .init           = rcu_sync_torture_init,
 709         .readlock       = srcu_torture_read_lock_raw,
 710         .read_delay     = srcu_read_delay,
 711         .readunlock     = srcu_torture_read_unlock_raw,
 712         .completed      = srcu_torture_completed,
 713         .deferred_free  = rcu_sync_torture_deferred_free,
 714         .sync           = srcu_torture_synchronize,
 715         .call           = NULL,
 716         .cb_barrier     = NULL,
 717         .stats          = srcu_torture_stats,
 718         .name           = "srcu_raw_sync"
 719 };
 720
 721 static void srcu_torture_synchronize_expedited(void)
 722 {
 723         synchronize_srcu_expedited(&srcu_ctl);
 724 }
 725
 726 static struct rcu_torture_ops srcu_expedited_ops = {
 727         .init           = rcu_sync_torture_init,
 728         .readlock       = srcu_torture_read_lock,
 729         .read_delay     = srcu_read_delay,
 730         .readunlock     = srcu_torture_read_unlock,
 731         .completed      = srcu_torture_completed,
 732         .deferred_free  = rcu_sync_torture_deferred_free,
 733         .sync           = srcu_torture_synchronize_expedited,
 734         .call           = NULL,
 735         .cb_barrier     = NULL,
 736         .stats          = srcu_torture_stats,
 737         .name           = "srcu_expedited"
 738 };
 739
 740 /*
 741  * Definitions for sched torture testing.
 742  */
 743
 744 static int sched_torture_read_lock(void)
 745 {
 746         preempt_disable();
 747         return 0;
 748 }
 749
 750 static void sched_torture_read_unlock(int idx)
 751 {
 752         preempt_enable();
 753 }
 754
 755 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
 756 {
 757         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
 758 }
 759
 760 static struct rcu_torture_ops sched_ops = {
 761         .init           = rcu_sync_torture_init,
 762         .readlock       = sched_torture_read_lock,
 763         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 764         .readunlock     = sched_torture_read_unlock,
 765         .completed      = rcu_no_completed,
 766         .deferred_free  = rcu_sched_torture_deferred_free,
 767         .sync           = synchronize_sched,
 768         .cb_barrier     = rcu_barrier_sched,
 769         .fqs            = rcu_sched_force_quiescent_state,
 770         .stats          = NULL,
 771         .irq_capable    = 1,
 772         .name           = "sched"
 773 };
 774
 775 static struct rcu_torture_ops sched_sync_ops = {
 776         .init           = rcu_sync_torture_init,
 777         .readlock       = sched_torture_read_lock,
 778         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 779         .readunlock     = sched_torture_read_unlock,
 780         .completed      = rcu_no_completed,
 781         .deferred_free  = rcu_sync_torture_deferred_free,
 782         .sync           = synchronize_sched,
 783         .cb_barrier     = NULL,
 784         .fqs            = rcu_sched_force_quiescent_state,
 785         .stats          = NULL,
 786         .name           = "sched_sync"
 787 };
 788
 789 static struct rcu_torture_ops sched_expedited_ops = {
 790         .init           = rcu_sync_torture_init,
 791         .readlock       = sched_torture_read_lock,
 792         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 793         .readunlock     = sched_torture_read_unlock,
 794         .completed      = rcu_no_completed,
 795         .deferred_free  = rcu_sync_torture_deferred_free,
 796         .sync           = synchronize_sched_expedited,
 797         .cb_barrier     = NULL,
 798         .fqs            = rcu_sched_force_quiescent_state,
 799         .stats          = NULL,
 800         .irq_capable    = 1,
 801         .name           = "sched_expedited"
 802 };
 803
 804 /*
 805  * RCU torture priority-boost testing.  Runs one real-time thread per
 806  * CPU for moderate bursts, repeatedly registering RCU callbacks and
 807  * spinning waiting for them to be invoked.  If a given callback takes
 808  * too long to be invoked, we assume that priority inversion has occurred.
 809  */
 810
 811 struct rcu_boost_inflight {
 812         struct rcu_head rcu;
 813         int inflight;
 814 };
 815
 816 static void rcu_torture_boost_cb(struct rcu_head *head)
 817 {
 818         struct rcu_boost_inflight *rbip =
 819                 container_of(head, struct rcu_boost_inflight, rcu);
 820
 821         smp_mb(); /* Ensure RCU-core accesses precede clearing ->inflight */
 822         rbip->inflight = 0;
 823 }
 824
 825 static int rcu_torture_boost(void *arg)
 826 {
 827         unsigned long call_rcu_time;
 828         unsigned long endtime;
 829         unsigned long oldstarttime;
 830         struct rcu_boost_inflight rbi = { .inflight = 0 };
 831         struct sched_param sp;
 832
 833         VERBOSE_PRINTK_STRING("rcu_torture_boost started");
 834
 835         /* Set real-time priority. */
 836         sp.sched_priority = 1;
 837         if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 838                 VERBOSE_PRINTK_STRING("rcu_torture_boost RT prio failed!");
 839                 n_rcu_torture_boost_rterror++;
 840         }
 841
 842         init_rcu_head_on_stack(&rbi.rcu);
 843         /* Each pass through the following loop does one boost-test cycle. */
 844         do {
 845                 /* Wait for the next test interval. */
 846                 oldstarttime = boost_starttime;
 847                 while (ULONG_CMP_LT(jiffies, oldstarttime)) {
 848                         schedule_timeout_uninterruptible(1);
 849                         rcu_stutter_wait("rcu_torture_boost");
 850                         if (kthread_should_stop() ||
 851                             fullstop != FULLSTOP_DONTSTOP)
 852                                 goto checkwait;
 853                 }
 854
 855                 /* Do one boost-test interval. */
 856                 endtime = oldstarttime + test_boost_duration * HZ;
 857                 call_rcu_time = jiffies;
 858                 while (ULONG_CMP_LT(jiffies, endtime)) {
 859                         /* If we don't have a callback in flight, post one. */
 860                         if (!rbi.inflight) {
 861                                 smp_mb(); /* RCU core before ->inflight = 1. */
 862                                 rbi.inflight = 1;
 863                                 call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 864                                 if (jiffies - call_rcu_time >
 865                                          test_boost_duration * HZ - HZ / 2) {
 866                                         VERBOSE_PRINTK_STRING("rcu_torture_boost boosting failed");
 867                                         n_rcu_torture_boost_failure++;
 868                                 }
 869                                 call_rcu_time = jiffies;
 870                         }
 871                         cond_resched();
 872                         rcu_stutter_wait("rcu_torture_boost");
 873                         if (kthread_should_stop() ||
 874                             fullstop != FULLSTOP_DONTSTOP)
 875                                 goto checkwait;
 876                 }
 877
 878                 /*
 879                  * Set the start time of the next test interval.
 880                  * Yes, this is vulnerable to long delays, but such
 881                  * delays simply cause a false negative for the next
 882                  * interval.  Besides, we are running at RT priority,
 883                  * so delays should be relatively rare.
 884                  */
 885                 while (oldstarttime == boost_starttime &&
 886                        !kthread_should_stop()) {
 887                         if (mutex_trylock(&boost_mutex)) {
 888                                 boost_starttime = jiffies +
 889                                                   test_boost_interval * HZ;
 890                                 n_rcu_torture_boosts++;
 891                                 mutex_unlock(&boost_mutex);
 892                                 break;
 893                         }
 894                         schedule_timeout_uninterruptible(1);
 895                 }
 896
 897                 /* Go do the stutter. */
 898 checkwait:      rcu_stutter_wait("rcu_torture_boost");
 899         } while (!kthread_should_stop() && fullstop  == FULLSTOP_DONTSTOP);
 900
 901         /* Clean up and exit. */
 902         VERBOSE_PRINTK_STRING("rcu_torture_boost task stopping");
 903         rcutorture_shutdown_absorb("rcu_torture_boost");
 904         while (!kthread_should_stop() || rbi.inflight)
 905                 schedule_timeout_uninterruptible(1);
 906         smp_mb(); /* order accesses to ->inflight before stack-frame death. */
 907         destroy_rcu_head_on_stack(&rbi.rcu);
 908         return 0;
 909 }
 910
 911 /*
 912  * RCU torture force-quiescent-state kthread.  Repeatedly induces
 913  * bursts of calls to force_quiescent_state(), increasing the probability
 914  * of occurrence of some important types of race conditions.
 915  */
 916 static int
 917 rcu_torture_fqs(void *arg)
 918 {
 919         unsigned long fqs_resume_time;
 920         int fqs_burst_remaining;
 921
 922         VERBOSE_PRINTK_STRING("rcu_torture_fqs task started");
 923         do {
 924                 fqs_resume_time = jiffies + fqs_stutter * HZ;
 925                 while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
 926                        !kthread_should_stop()) {
 927                         schedule_timeout_interruptible(1);
 928                 }
 929                 fqs_burst_remaining = fqs_duration;
 930                 while (fqs_burst_remaining > 0 &&
 931                        !kthread_should_stop()) {
 932                         cur_ops->fqs();
 933                         udelay(fqs_holdoff);
 934                         fqs_burst_remaining -= fqs_holdoff;
 935                 }
 936                 rcu_stutter_wait("rcu_torture_fqs");
 937         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 938         VERBOSE_PRINTK_STRING("rcu_torture_fqs task stopping");
 939         rcutorture_shutdown_absorb("rcu_torture_fqs");
 940         while (!kthread_should_stop())
 941                 schedule_timeout_uninterruptible(1);
 942         return 0;
 943 }
 944
 945 /*
 946  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 947  * for that pointed to by rcu_torture_current, freeing the old structure
 948  * after a series of grace periods (the "pipeline").
 949  */
 950 static int
 951 rcu_torture_writer(void *arg)
 952 {
 953         int i;
 954         long oldbatch = rcu_batches_completed();
 955         struct rcu_torture *rp;
 956         struct rcu_torture *old_rp;
 957         static DEFINE_RCU_RANDOM(rand);
 958
 959         VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
 960         set_user_nice(current, 19);
 961
 962         do {
 963                 schedule_timeout_uninterruptible(1);
 964                 rp = rcu_torture_alloc();
 965                 if (rp == NULL)
 966                         continue;
 967                 rp->rtort_pipe_count = 0;
 968                 udelay(rcu_random(&rand) & 0x3ff);
 969                 old_rp = rcu_dereference_check(rcu_torture_current,
 970                                                current == writer_task);
 971                 rp->rtort_mbtest = 1;
 972                 rcu_assign_pointer(rcu_torture_current, rp);
 973                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
 974                 if (old_rp) {
 975                         i = old_rp->rtort_pipe_count;
 976                         if (i > RCU_TORTURE_PIPE_LEN)
 977                                 i = RCU_TORTURE_PIPE_LEN;
 978                         atomic_inc(&rcu_torture_wcount[i]);
 979                         old_rp->rtort_pipe_count++;
 980                         cur_ops->deferred_free(old_rp);
 981                 }
 982                 rcutorture_record_progress(++rcu_torture_current_version);
 983                 oldbatch = cur_ops->completed();
 984                 rcu_stutter_wait("rcu_torture_writer");
 985         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 986         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
 987         rcutorture_shutdown_absorb("rcu_torture_writer");
 988         while (!kthread_should_stop())
 989                 schedule_timeout_uninterruptible(1);
 990         return 0;
 991 }
 992
 993 /*
 994  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
 995  * delay between calls.
 996  */
 997 static int
 998 rcu_torture_fakewriter(void *arg)
 999 {
1000         DEFINE_RCU_RANDOM(rand);
1001
1002         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
1003         set_user_nice(current, 19);
1004
1005         do {
1006                 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
1007                 udelay(rcu_random(&rand) & 0x3ff);
1008                 if (cur_ops->cb_barrier != NULL &&
1009                     rcu_random(&rand) % (nfakewriters * 8) == 0)
1010                         cur_ops->cb_barrier();
1011                 else
1012                         cur_ops->sync();
1013                 rcu_stutter_wait("rcu_torture_fakewriter");
1014         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1015
1016         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
1017         rcutorture_shutdown_absorb("rcu_torture_fakewriter");
1018         while (!kthread_should_stop())
1019                 schedule_timeout_uninterruptible(1);
1020         return 0;
1021 }
1022
1023 void rcutorture_trace_dump(void)
1024 {
1025         static atomic_t beenhere = ATOMIC_INIT(0);
1026
1027         if (atomic_read(&beenhere))
1028                 return;
1029         if (atomic_xchg(&beenhere, 1) != 0)
1030                 return;
1031         do_trace_rcu_torture_read(cur_ops->name, (struct rcu_head *)~0UL);
1032         ftrace_dump(DUMP_ALL);
1033 }
1034
1035 /*
1036  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
1037  * incrementing the corresponding element of the pipeline array.  The
1038  * counter in the element should never be greater than 1, otherwise, the
1039  * RCU implementation is broken.
1040  */
1041 static void rcu_torture_timer(unsigned long unused)
1042 {
1043         int idx;
1044         int completed;
1045         static DEFINE_RCU_RANDOM(rand);
1046         static DEFINE_SPINLOCK(rand_lock);
1047         struct rcu_torture *p;
1048         int pipe_count;
1049
1050         idx = cur_ops->readlock();
1051         completed = cur_ops->completed();
1052         p = rcu_dereference_check(rcu_torture_current,
1053                                   rcu_read_lock_bh_held() ||
1054                                   rcu_read_lock_sched_held() ||
1055                                   srcu_read_lock_held(&srcu_ctl));
1056         if (p == NULL) {
1057                 /* Leave because rcu_torture_writer is not yet underway */
1058                 cur_ops->readunlock(idx);
1059                 return;
1060         }
1061         do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu);
1062         if (p->rtort_mbtest == 0)
1063                 atomic_inc(&n_rcu_torture_mberror);
1064         spin_lock(&rand_lock);
1065         cur_ops->read_delay(&rand);
1066         n_rcu_torture_timers++;
1067         spin_unlock(&rand_lock);
1068         preempt_disable();
1069         pipe_count = p->rtort_pipe_count;
1070         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1071                 /* Should not happen, but... */
1072                 pipe_count = RCU_TORTURE_PIPE_LEN;
1073         }
1074         if (pipe_count > 1)
1075                 rcutorture_trace_dump();
1076         __this_cpu_inc(rcu_torture_count[pipe_count]);
1077         completed = cur_ops->completed() - completed;
1078         if (completed > RCU_TORTURE_PIPE_LEN) {
1079                 /* Should not happen, but... */
1080                 completed = RCU_TORTURE_PIPE_LEN;
1081         }
1082         __this_cpu_inc(rcu_torture_batch[completed]);
1083         preempt_enable();
1084         cur_ops->readunlock(idx);
1085 }
1086
1087 /*
1088  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
1089  * incrementing the corresponding element of the pipeline array.  The
1090  * counter in the element should never be greater than 1, otherwise, the
1091  * RCU implementation is broken.
1092  */
1093 static int
1094 rcu_torture_reader(void *arg)
1095 {
1096         int completed;
1097         int idx;
1098         DEFINE_RCU_RANDOM(rand);
1099         struct rcu_torture *p;
1100         int pipe_count;
1101         struct timer_list t;
1102
1103         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
1104         set_user_nice(current, 19);
1105         if (irqreader && cur_ops->irq_capable)
1106                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
1107
1108         do {
1109                 if (irqreader && cur_ops->irq_capable) {
1110                         if (!timer_pending(&t))
1111                                 mod_timer(&t, jiffies + 1);
1112                 }
1113                 idx = cur_ops->readlock();
1114                 completed = cur_ops->completed();
1115                 p = rcu_dereference_check(rcu_torture_current,
1116                                           rcu_read_lock_bh_held() ||
1117                                           rcu_read_lock_sched_held() ||
1118                                           srcu_read_lock_held(&srcu_ctl));
1119                 if (p == NULL) {
1120                         /* Wait for rcu_torture_writer to get underway */
1121                         cur_ops->readunlock(idx);
1122                         schedule_timeout_interruptible(HZ);
1123                         continue;
1124                 }
1125                 do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu);
1126                 if (p->rtort_mbtest == 0)
1127                         atomic_inc(&n_rcu_torture_mberror);
1128                 cur_ops->read_delay(&rand);
1129                 preempt_disable();
1130                 pipe_count = p->rtort_pipe_count;
1131                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1132                         /* Should not happen, but... */
1133                         pipe_count = RCU_TORTURE_PIPE_LEN;
1134                 }
1135                 if (pipe_count > 1)
1136                         rcutorture_trace_dump();
1137                 __this_cpu_inc(rcu_torture_count[pipe_count]);
1138                 completed = cur_ops->completed() - completed;
1139                 if (completed > RCU_TORTURE_PIPE_LEN) {
1140                         /* Should not happen, but... */
1141                         completed = RCU_TORTURE_PIPE_LEN;
1142                 }
1143                 __this_cpu_inc(rcu_torture_batch[completed]);
1144                 preempt_enable();
1145                 cur_ops->readunlock(idx);
1146                 schedule();
1147                 rcu_stutter_wait("rcu_torture_reader");
1148         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1149         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
1150         rcutorture_shutdown_absorb("rcu_torture_reader");
1151         if (irqreader && cur_ops->irq_capable)
1152                 del_timer_sync(&t);
1153         while (!kthread_should_stop())
1154                 schedule_timeout_uninterruptible(1);
1155         return 0;
1156 }
1157
1158 /*
1159  * Create an RCU-torture statistics message in the specified buffer.
1160  */
1161 static int
1162 rcu_torture_printk(char *page)
1163 {
1164         int cnt = 0;
1165         int cpu;
1166         int i;
1167         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1168         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1169
1170         for_each_possible_cpu(cpu) {
1171                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1172                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1173                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1174                 }
1175         }
1176         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1177                 if (pipesummary[i] != 0)
1178                         break;
1179         }
1180         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
1181         cnt += sprintf(&page[cnt],
1182                        "rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
1183                        rcu_torture_current,
1184                        rcu_torture_current_version,
1185                        list_empty(&rcu_torture_freelist),
1186                        atomic_read(&n_rcu_torture_alloc),
1187                        atomic_read(&n_rcu_torture_alloc_fail),
1188                        atomic_read(&n_rcu_torture_free));
1189         cnt += sprintf(&page[cnt], "rtmbe: %d rtbke: %ld rtbre: %ld ",
1190                        atomic_read(&n_rcu_torture_mberror),
1191                        n_rcu_torture_boost_ktrerror,
1192                        n_rcu_torture_boost_rterror);
1193         cnt += sprintf(&page[cnt], "rtbf: %ld rtb: %ld nt: %ld ",
1194                        n_rcu_torture_boost_failure,
1195                        n_rcu_torture_boosts,
1196                        n_rcu_torture_timers);
1197         cnt += sprintf(&page[cnt],
1198                        "onoff: %ld/%ld:%ld/%ld %d,%d:%d,%d %lu:%lu (HZ=%d) ",
1199                        n_online_successes, n_online_attempts,
1200                        n_offline_successes, n_offline_attempts,
1201                        min_online, max_online,
1202                        min_offline, max_offline,
1203                        sum_online, sum_offline, HZ);
1204         cnt += sprintf(&page[cnt], "barrier: %ld/%ld:%ld",
1205                        n_barrier_successes,
1206                        n_barrier_attempts,
1207                        n_rcu_torture_barrier_error);
1208         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1209         if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1210             n_rcu_torture_barrier_error != 0 ||
1211             n_rcu_torture_boost_ktrerror != 0 ||
1212             n_rcu_torture_boost_rterror != 0 ||
1213             n_rcu_torture_boost_failure != 0 ||
1214             i > 1) {
1215                 cnt += sprintf(&page[cnt], "!!! ");
1216                 atomic_inc(&n_rcu_torture_error);
1217                 WARN_ON_ONCE(1);
1218         }
1219         cnt += sprintf(&page[cnt], "Reader Pipe: ");
1220         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1221                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
1222         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1223         cnt += sprintf(&page[cnt], "Reader Batch: ");
1224         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1225                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
1226         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1227         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
1228         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1229                 cnt += sprintf(&page[cnt], " %d",
1230                                atomic_read(&rcu_torture_wcount[i]));
1231         }
1232         cnt += sprintf(&page[cnt], "\n");
1233         if (cur_ops->stats)
1234                 cnt += cur_ops->stats(&page[cnt]);
1235         return cnt;
1236 }
1237
1238 /*
1239  * Print torture statistics.  Caller must ensure that there is only
1240  * one call to this function at a given time!!!  This is normally
1241  * accomplished by relying on the module system to only have one copy
1242  * of the module loaded, and then by giving the rcu_torture_stats
1243  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1244  * thread is not running).
1245  */
1246 static void
1247 rcu_torture_stats_print(void)
1248 {
1249         int cnt;
1250
1251         cnt = rcu_torture_printk(printk_buf);
1252         pr_alert("%s", printk_buf);
1253 }
1254
1255 /*
1256  * Periodically prints torture statistics, if periodic statistics printing
1257  * was specified via the stat_interval module parameter.
1258  *
1259  * No need to worry about fullstop here, since this one doesn't reference
1260  * volatile state or register callbacks.
1261  */
1262 static int
1263 rcu_torture_stats(void *arg)
1264 {
1265         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
1266         do {
1267                 schedule_timeout_interruptible(stat_interval * HZ);
1268                 rcu_torture_stats_print();
1269                 rcutorture_shutdown_absorb("rcu_torture_stats");
1270         } while (!kthread_should_stop());
1271         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
1272         return 0;
1273 }
1274
1275 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
1276
1277 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
1278  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
1279  */
1280 static void rcu_torture_shuffle_tasks(void)
1281 {
1282         int i;
1283
1284         cpumask_setall(shuffle_tmp_mask);
1285         get_online_cpus();
1286
1287         /* No point in shuffling if there is only one online CPU (ex: UP) */
1288         if (num_online_cpus() == 1) {
1289                 put_online_cpus();
1290                 return;
1291         }
1292
1293         if (rcu_idle_cpu != -1)
1294                 cpumask_clear_cpu(rcu_idle_cpu, shuffle_tmp_mask);
1295
1296         set_cpus_allowed_ptr(current, shuffle_tmp_mask);
1297
1298         if (reader_tasks) {
1299                 for (i = 0; i < nrealreaders; i++)
1300                         if (reader_tasks[i])
1301                                 set_cpus_allowed_ptr(reader_tasks[i],
1302                                                      shuffle_tmp_mask);
1303         }
1304
1305         if (fakewriter_tasks) {
1306                 for (i = 0; i < nfakewriters; i++)
1307                         if (fakewriter_tasks[i])
1308                                 set_cpus_allowed_ptr(fakewriter_tasks[i],
1309                                                      shuffle_tmp_mask);
1310         }
1311
1312         if (writer_task)
1313                 set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
1314
1315         if (stats_task)
1316                 set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
1317
1318         if (rcu_idle_cpu == -1)
1319                 rcu_idle_cpu = num_online_cpus() - 1;
1320         else
1321                 rcu_idle_cpu--;
1322
1323         put_online_cpus();
1324 }
1325
1326 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
1327  * system to become idle at a time and cut off its timer ticks. This is meant
1328  * to test the support for such tickless idle CPU in RCU.
1329  */
1330 static int
1331 rcu_torture_shuffle(void *arg)
1332 {
1333         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
1334         do {
1335                 schedule_timeout_interruptible(shuffle_interval * HZ);
1336                 rcu_torture_shuffle_tasks();
1337                 rcutorture_shutdown_absorb("rcu_torture_shuffle");
1338         } while (!kthread_should_stop());
1339         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
1340         return 0;
1341 }
1342
1343 /* Cause the rcutorture test to "stutter", starting and stopping all
1344  * threads periodically.
1345  */
1346 static int
1347 rcu_torture_stutter(void *arg)
1348 {
1349         VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
1350         do {
1351                 schedule_timeout_interruptible(stutter * HZ);
1352                 stutter_pause_test = 1;
1353                 if (!kthread_should_stop())
1354                         schedule_timeout_interruptible(stutter * HZ);
1355                 stutter_pause_test = 0;
1356                 rcutorture_shutdown_absorb("rcu_torture_stutter");
1357         } while (!kthread_should_stop());
1358         VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
1359         return 0;
1360 }
1361
1362 static inline void
1363 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, char *tag)
1364 {
1365         pr_alert("%s" TORTURE_FLAG
1366                  "--- %s: nreaders=%d nfakewriters=%d "
1367                  "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1368                  "shuffle_interval=%d stutter=%d irqreader=%d "
1369                  "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1370                  "test_boost=%d/%d test_boost_interval=%d "
1371                  "test_boost_duration=%d shutdown_secs=%d "
1372                  "stall_cpu=%d stall_cpu_holdoff=%d "
1373                  "n_barrier_cbs=%d "
1374                  "onoff_interval=%d onoff_holdoff=%d\n",
1375                  torture_type, tag, nrealreaders, nfakewriters,
1376                  stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1377                  stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1378                  test_boost, cur_ops->can_boost,
1379                  test_boost_interval, test_boost_duration, shutdown_secs,
1380                  stall_cpu, stall_cpu_holdoff,
1381                  n_barrier_cbs,
1382                  onoff_interval, onoff_holdoff);
1383 }
1384
1385 static struct notifier_block rcutorture_shutdown_nb = {
1386         .notifier_call = rcutorture_shutdown_notify,
1387 };
1388
1389 static void rcutorture_booster_cleanup(int cpu)
1390 {
1391         struct task_struct *t;
1392
1393         if (boost_tasks[cpu] == NULL)
1394                 return;
1395         mutex_lock(&boost_mutex);
1396         VERBOSE_PRINTK_STRING("Stopping rcu_torture_boost task");
1397         t = boost_tasks[cpu];
1398         boost_tasks[cpu] = NULL;
1399         mutex_unlock(&boost_mutex);
1400
1401         /* This must be outside of the mutex, otherwise deadlock! */
1402         kthread_stop(t);
1403         boost_tasks[cpu] = NULL;
1404 }
1405
1406 static int rcutorture_booster_init(int cpu)
1407 {
1408         int retval;
1409
1410         if (boost_tasks[cpu] != NULL)
1411                 return 0;  /* Already created, nothing more to do. */
1412
1413         /* Don't allow time recalculation while creating a new task. */
1414         mutex_lock(&boost_mutex);
1415         VERBOSE_PRINTK_STRING("Creating rcu_torture_boost task");
1416         boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1417                                                   cpu_to_node(cpu),
1418                                                   "rcu_torture_boost");
1419         if (IS_ERR(boost_tasks[cpu])) {
1420                 retval = PTR_ERR(boost_tasks[cpu]);
1421                 VERBOSE_PRINTK_STRING("rcu_torture_boost task create failed");
1422                 n_rcu_torture_boost_ktrerror++;
1423                 boost_tasks[cpu] = NULL;
1424                 mutex_unlock(&boost_mutex);
1425                 return retval;
1426         }
1427         kthread_bind(boost_tasks[cpu], cpu);
1428         wake_up_process(boost_tasks[cpu]);
1429         mutex_unlock(&boost_mutex);
1430         return 0;
1431 }
1432
1433 /*
1434  * Cause the rcutorture test to shutdown the system after the test has
1435  * run for the time specified by the shutdown_secs module parameter.
1436  */
1437 static int
1438 rcu_torture_shutdown(void *arg)
1439 {
1440         long delta;
1441         unsigned long jiffies_snap;
1442
1443         VERBOSE_PRINTK_STRING("rcu_torture_shutdown task started");
1444         jiffies_snap = ACCESS_ONCE(jiffies);
1445         while (ULONG_CMP_LT(jiffies_snap, shutdown_time) &&
1446                !kthread_should_stop()) {
1447                 delta = shutdown_time - jiffies_snap;
1448                 if (verbose)
1449                         pr_alert("%s" TORTURE_FLAG
1450                                  "rcu_torture_shutdown task: %lu jiffies remaining\n",
1451                                  torture_type, delta);
1452                 schedule_timeout_interruptible(delta);
1453                 jiffies_snap = ACCESS_ONCE(jiffies);
1454         }
1455         if (kthread_should_stop()) {
1456                 VERBOSE_PRINTK_STRING("rcu_torture_shutdown task stopping");
1457                 return 0;
1458         }
1459
1460         /* OK, shut down the system. */
1461
1462         VERBOSE_PRINTK_STRING("rcu_torture_shutdown task shutting down system");
1463         shutdown_task = NULL;   /* Avoid self-kill deadlock. */
1464         rcu_torture_cleanup();  /* Get the success/failure message. */
1465         kernel_power_off();     /* Shut down the system. */
1466         return 0;
1467 }
1468
1469 #ifdef CONFIG_HOTPLUG_CPU
1470
1471 /*
1472  * Execute random CPU-hotplug operations at the interval specified
1473  * by the onoff_interval.
1474  */
1475 static int __cpuinit
1476 rcu_torture_onoff(void *arg)
1477 {
1478         int cpu;
1479         unsigned long delta;
1480         int maxcpu = -1;
1481         DEFINE_RCU_RANDOM(rand);
1482         int ret;
1483         unsigned long starttime;
1484
1485         VERBOSE_PRINTK_STRING("rcu_torture_onoff task started");
1486         for_each_online_cpu(cpu)
1487                 maxcpu = cpu;
1488         WARN_ON(maxcpu < 0);
1489         if (onoff_holdoff > 0) {
1490                 VERBOSE_PRINTK_STRING("rcu_torture_onoff begin holdoff");
1491                 schedule_timeout_interruptible(onoff_holdoff * HZ);
1492                 VERBOSE_PRINTK_STRING("rcu_torture_onoff end holdoff");
1493         }
1494         while (!kthread_should_stop()) {
1495                 cpu = (rcu_random(&rand) >> 4) % (maxcpu + 1);
1496                 if (cpu_online(cpu) && cpu_is_hotpluggable(cpu)) {
1497                         if (verbose)
1498                                 pr_alert("%s" TORTURE_FLAG
1499                                          "rcu_torture_onoff task: offlining %d\n",
1500                                          torture_type, cpu);
1501                         starttime = jiffies;
1502                         n_offline_attempts++;
1503                         ret = cpu_down(cpu);
1504                         if (ret) {
1505                                 if (verbose)
1506                                         pr_alert("%s" TORTURE_FLAG
1507                                                  "rcu_torture_onoff task: offline %d failed: errno %d\n",
1508                                                  torture_type, cpu, ret);
1509                         } else {
1510                                 if (verbose)
1511                                         pr_alert("%s" TORTURE_FLAG
1512                                                  "rcu_torture_onoff task: offlined %d\n",
1513                                                  torture_type, cpu);
1514                                 n_offline_successes++;
1515                                 delta = jiffies - starttime;
1516                                 sum_offline += delta;
1517                                 if (min_offline < 0) {
1518                                         min_offline = delta;
1519                                         max_offline = delta;
1520                                 }
1521                                 if (min_offline > delta)
1522                                         min_offline = delta;
1523                                 if (max_offline < delta)
1524                                         max_offline = delta;
1525                         }
1526                 } else if (cpu_is_hotpluggable(cpu)) {
1527                         if (verbose)
1528                                 pr_alert("%s" TORTURE_FLAG
1529                                          "rcu_torture_onoff task: onlining %d\n",
1530                                          torture_type, cpu);
1531                         starttime = jiffies;
1532                         n_online_attempts++;
1533                         if (cpu_up(cpu) == 0) {
1534                                 if (verbose)
1535                                         pr_alert("%s" TORTURE_FLAG
1536                                                  "rcu_torture_onoff task: onlined %d\n",
1537                                                  torture_type, cpu);
1538                                 n_online_successes++;
1539                                 delta = jiffies - starttime;
1540                                 sum_online += delta;
1541                                 if (min_online < 0) {
1542                                         min_online = delta;
1543                                         max_online = delta;
1544                                 }
1545                                 if (min_online > delta)
1546                                         min_online = delta;
1547                                 if (max_online < delta)
1548                                         max_online = delta;
1549                         }
1550                 }
1551                 schedule_timeout_interruptible(onoff_interval * HZ);
1552         }
1553         VERBOSE_PRINTK_STRING("rcu_torture_onoff task stopping");
1554         return 0;
1555 }
1556
1557 static int __cpuinit
1558 rcu_torture_onoff_init(void)
1559 {
1560         int ret;
1561
1562         if (onoff_interval <= 0)
1563                 return 0;
1564         onoff_task = kthread_run(rcu_torture_onoff, NULL, "rcu_torture_onoff");
1565         if (IS_ERR(onoff_task)) {
1566                 ret = PTR_ERR(onoff_task);
1567                 onoff_task = NULL;
1568                 return ret;
1569         }
1570         return 0;
1571 }
1572
1573 static void rcu_torture_onoff_cleanup(void)
1574 {
1575         if (onoff_task == NULL)
1576                 return;
1577         VERBOSE_PRINTK_STRING("Stopping rcu_torture_onoff task");
1578         kthread_stop(onoff_task);
1579         onoff_task = NULL;
1580 }
1581
1582 #else /* #ifdef CONFIG_HOTPLUG_CPU */
1583
1584 static int
1585 rcu_torture_onoff_init(void)
1586 {
1587         return 0;
1588 }
1589
1590 static void rcu_torture_onoff_cleanup(void)
1591 {
1592 }
1593
1594 #endif /* #else #ifdef CONFIG_HOTPLUG_CPU */
1595
1596 /*
1597  * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
1598  * induces a CPU stall for the time specified by stall_cpu.
1599  */
1600 static int __cpuinit rcu_torture_stall(void *args)
1601 {
1602         unsigned long stop_at;
1603
1604         VERBOSE_PRINTK_STRING("rcu_torture_stall task started");
1605         if (stall_cpu_holdoff > 0) {
1606                 VERBOSE_PRINTK_STRING("rcu_torture_stall begin holdoff");
1607                 schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1608                 VERBOSE_PRINTK_STRING("rcu_torture_stall end holdoff");
1609         }
1610         if (!kthread_should_stop()) {
1611                 stop_at = get_seconds() + stall_cpu;
1612                 /* RCU CPU stall is expected behavior in following code. */
1613                 pr_alert("rcu_torture_stall start.\n");
1614                 rcu_read_lock();
1615                 preempt_disable();
1616                 while (ULONG_CMP_LT(get_seconds(), stop_at))
1617                         continue;  /* Induce RCU CPU stall warning. */
1618                 preempt_enable();
1619                 rcu_read_unlock();
1620                 pr_alert("rcu_torture_stall end.\n");
1621         }
1622         rcutorture_shutdown_absorb("rcu_torture_stall");
1623         while (!kthread_should_stop())
1624                 schedule_timeout_interruptible(10 * HZ);
1625         return 0;
1626 }
1627
1628 /* Spawn CPU-stall kthread, if stall_cpu specified. */
1629 static int __init rcu_torture_stall_init(void)
1630 {
1631         int ret;
1632
1633         if (stall_cpu <= 0)
1634                 return 0;
1635         stall_task = kthread_run(rcu_torture_stall, NULL, "rcu_torture_stall");
1636         if (IS_ERR(stall_task)) {
1637                 ret = PTR_ERR(stall_task);
1638                 stall_task = NULL;
1639                 return ret;
1640         }
1641         return 0;
1642 }
1643
1644 /* Clean up after the CPU-stall kthread, if one was spawned. */
1645 static void rcu_torture_stall_cleanup(void)
1646 {
1647         if (stall_task == NULL)
1648                 return;
1649         VERBOSE_PRINTK_STRING("Stopping rcu_torture_stall_task.");
1650         kthread_stop(stall_task);
1651         stall_task = NULL;
1652 }
1653
1654 /* Callback function for RCU barrier testing. */
1655 void rcu_torture_barrier_cbf(struct rcu_head *rcu)
1656 {
1657         atomic_inc(&barrier_cbs_invoked);
1658 }
1659
1660 /* kthread function to register callbacks used to test RCU barriers. */
1661 static int rcu_torture_barrier_cbs(void *arg)
1662 {
1663         long myid = (long)arg;
1664         bool lastphase = 0;
1665         struct rcu_head rcu;
1666
1667         init_rcu_head_on_stack(&rcu);
1668         VERBOSE_PRINTK_STRING("rcu_torture_barrier_cbs task started");
1669         set_user_nice(current, 19);
1670         do {
1671                 wait_event(barrier_cbs_wq[myid],
1672                            barrier_phase != lastphase ||
1673                            kthread_should_stop() ||
1674                            fullstop != FULLSTOP_DONTSTOP);
1675                 lastphase = barrier_phase;
1676                 smp_mb(); /* ensure barrier_phase load before ->call(). */
1677                 if (kthread_should_stop() || fullstop != FULLSTOP_DONTSTOP)
1678                         break;
1679                 cur_ops->call(&rcu, rcu_torture_barrier_cbf);
1680                 if (atomic_dec_and_test(&barrier_cbs_count))
1681                         wake_up(&barrier_wq);
1682         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1683         VERBOSE_PRINTK_STRING("rcu_torture_barrier_cbs task stopping");
1684         rcutorture_shutdown_absorb("rcu_torture_barrier_cbs");
1685         while (!kthread_should_stop())
1686                 schedule_timeout_interruptible(1);
1687         cur_ops->cb_barrier();
1688         destroy_rcu_head_on_stack(&rcu);
1689         return 0;
1690 }
1691
1692 /* kthread function to drive and coordinate RCU barrier testing. */
1693 static int rcu_torture_barrier(void *arg)
1694 {
1695         int i;
1696
1697         VERBOSE_PRINTK_STRING("rcu_torture_barrier task starting");
1698         do {
1699                 atomic_set(&barrier_cbs_invoked, 0);
1700                 atomic_set(&barrier_cbs_count, n_barrier_cbs);
1701                 smp_mb(); /* Ensure barrier_phase after prior assignments. */
1702                 barrier_phase = !barrier_phase;
1703                 for (i = 0; i < n_barrier_cbs; i++)
1704                         wake_up(&barrier_cbs_wq[i]);
1705                 wait_event(barrier_wq,
1706                            atomic_read(&barrier_cbs_count) == 0 ||
1707                            kthread_should_stop() ||
1708                            fullstop != FULLSTOP_DONTSTOP);
1709                 if (kthread_should_stop() || fullstop != FULLSTOP_DONTSTOP)
1710                         break;
1711                 n_barrier_attempts++;
1712                 cur_ops->cb_barrier();
1713                 if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
1714                         n_rcu_torture_barrier_error++;
1715                         WARN_ON_ONCE(1);
1716                 }
1717                 n_barrier_successes++;
1718                 schedule_timeout_interruptible(HZ / 10);
1719         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1720         VERBOSE_PRINTK_STRING("rcu_torture_barrier task stopping");
1721         rcutorture_shutdown_absorb("rcu_torture_barrier");
1722         while (!kthread_should_stop())
1723                 schedule_timeout_interruptible(1);
1724         return 0;
1725 }
1726
1727 /* Initialize RCU barrier testing. */
1728 static int rcu_torture_barrier_init(void)
1729 {
1730         int i;
1731         int ret;
1732
1733         if (n_barrier_cbs == 0)
1734                 return 0;
1735         if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
1736                 pr_alert("%s" TORTURE_FLAG
1737                          " Call or barrier ops missing for %s,\n",
1738                          torture_type, cur_ops->name);
1739                 pr_alert("%s" TORTURE_FLAG
1740                          " RCU barrier testing omitted from run.\n",
1741                          torture_type);
1742                 return 0;
1743         }
1744         atomic_set(&barrier_cbs_count, 0);
1745         atomic_set(&barrier_cbs_invoked, 0);
1746         barrier_cbs_tasks =
1747                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_tasks[0]),
1748                         GFP_KERNEL);
1749         barrier_cbs_wq =
1750                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_wq[0]),
1751                         GFP_KERNEL);
1752         if (barrier_cbs_tasks == NULL || barrier_cbs_wq == 0)
1753                 return -ENOMEM;
1754         for (i = 0; i < n_barrier_cbs; i++) {
1755                 init_waitqueue_head(&barrier_cbs_wq[i]);
1756                 barrier_cbs_tasks[i] = kthread_run(rcu_torture_barrier_cbs,
1757                                                    (void *)(long)i,
1758                                                    "rcu_torture_barrier_cbs");
1759                 if (IS_ERR(barrier_cbs_tasks[i])) {
1760                         ret = PTR_ERR(barrier_cbs_tasks[i]);
1761                         VERBOSE_PRINTK_ERRSTRING("Failed to create rcu_torture_barrier_cbs");
1762                         barrier_cbs_tasks[i] = NULL;
1763                         return ret;
1764                 }
1765         }
1766         barrier_task = kthread_run(rcu_torture_barrier, NULL,
1767                                    "rcu_torture_barrier");
1768         if (IS_ERR(barrier_task)) {
1769                 ret = PTR_ERR(barrier_task);
1770                 VERBOSE_PRINTK_ERRSTRING("Failed to create rcu_torture_barrier");
1771                 barrier_task = NULL;
1772         }
1773         return 0;
1774 }
1775
1776 /* Clean up after RCU barrier testing. */
1777 static void rcu_torture_barrier_cleanup(void)
1778 {
1779         int i;
1780
1781         if (barrier_task != NULL) {
1782                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_barrier task");
1783                 kthread_stop(barrier_task);
1784                 barrier_task = NULL;
1785         }
1786         if (barrier_cbs_tasks != NULL) {
1787                 for (i = 0; i < n_barrier_cbs; i++) {
1788                         if (barrier_cbs_tasks[i] != NULL) {
1789                                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_barrier_cbs task");
1790                                 kthread_stop(barrier_cbs_tasks[i]);
1791                                 barrier_cbs_tasks[i] = NULL;
1792                         }
1793                 }
1794                 kfree(barrier_cbs_tasks);
1795                 barrier_cbs_tasks = NULL;
1796         }
1797         if (barrier_cbs_wq != NULL) {
1798                 kfree(barrier_cbs_wq);
1799                 barrier_cbs_wq = NULL;
1800         }
1801 }
1802
1803 static int rcutorture_cpu_notify(struct notifier_block *self,
1804                                  unsigned long action, void *hcpu)
1805 {
1806         long cpu = (long)hcpu;
1807
1808         switch (action) {
1809         case CPU_ONLINE:
1810         case CPU_DOWN_FAILED:
1811                 (void)rcutorture_booster_init(cpu);
1812                 break;
1813         case CPU_DOWN_PREPARE:
1814                 rcutorture_booster_cleanup(cpu);
1815                 break;
1816         default:
1817                 break;
1818         }
1819         return NOTIFY_OK;
1820 }
1821
1822 static struct notifier_block rcutorture_cpu_nb = {
1823         .notifier_call = rcutorture_cpu_notify,
1824 };
1825
1826 static void
1827 rcu_torture_cleanup(void)
1828 {
1829         int i;
1830
1831         mutex_lock(&fullstop_mutex);
1832         rcutorture_record_test_transition();
1833         if (fullstop == FULLSTOP_SHUTDOWN) {
1834                 pr_warn(/* but going down anyway, so... */
1835                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
1836                 mutex_unlock(&fullstop_mutex);
1837                 schedule_timeout_uninterruptible(10);
1838                 if (cur_ops->cb_barrier != NULL)
1839                         cur_ops->cb_barrier();
1840                 return;
1841         }
1842         fullstop = FULLSTOP_RMMOD;
1843         mutex_unlock(&fullstop_mutex);
1844         unregister_reboot_notifier(&rcutorture_shutdown_nb);
1845         rcu_torture_barrier_cleanup();
1846         rcu_torture_stall_cleanup();
1847         if (stutter_task) {
1848                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
1849                 kthread_stop(stutter_task);
1850         }
1851         stutter_task = NULL;
1852         if (shuffler_task) {
1853                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
1854                 kthread_stop(shuffler_task);
1855                 free_cpumask_var(shuffle_tmp_mask);
1856         }
1857         shuffler_task = NULL;
1858
1859         if (writer_task) {
1860                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
1861                 kthread_stop(writer_task);
1862         }
1863         writer_task = NULL;
1864
1865         if (reader_tasks) {
1866                 for (i = 0; i < nrealreaders; i++) {
1867                         if (reader_tasks[i]) {
1868                                 VERBOSE_PRINTK_STRING(
1869                                         "Stopping rcu_torture_reader task");
1870                                 kthread_stop(reader_tasks[i]);
1871                         }
1872                         reader_tasks[i] = NULL;
1873                 }
1874                 kfree(reader_tasks);
1875                 reader_tasks = NULL;
1876         }
1877         rcu_torture_current = NULL;
1878
1879         if (fakewriter_tasks) {
1880                 for (i = 0; i < nfakewriters; i++) {
1881                         if (fakewriter_tasks[i]) {
1882                                 VERBOSE_PRINTK_STRING(
1883                                         "Stopping rcu_torture_fakewriter task");
1884                                 kthread_stop(fakewriter_tasks[i]);
1885                         }
1886                         fakewriter_tasks[i] = NULL;
1887                 }
1888                 kfree(fakewriter_tasks);
1889                 fakewriter_tasks = NULL;
1890         }
1891
1892         if (stats_task) {
1893                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
1894                 kthread_stop(stats_task);
1895         }
1896         stats_task = NULL;
1897
1898         if (fqs_task) {
1899                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_fqs task");
1900                 kthread_stop(fqs_task);
1901         }
1902         fqs_task = NULL;
1903         if ((test_boost == 1 && cur_ops->can_boost) ||
1904             test_boost == 2) {
1905                 unregister_cpu_notifier(&rcutorture_cpu_nb);
1906                 for_each_possible_cpu(i)
1907                         rcutorture_booster_cleanup(i);
1908         }
1909         if (shutdown_task != NULL) {
1910                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shutdown task");
1911                 kthread_stop(shutdown_task);
1912         }
1913         shutdown_task = NULL;
1914         rcu_torture_onoff_cleanup();
1915
1916         /* Wait for all RCU callbacks to fire.  */
1917
1918         if (cur_ops->cb_barrier != NULL)
1919                 cur_ops->cb_barrier();
1920
1921         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1922
1923         if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
1924                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1925         else if (n_online_successes != n_online_attempts ||
1926                  n_offline_successes != n_offline_attempts)
1927                 rcu_torture_print_module_parms(cur_ops,
1928                                                "End of test: RCU_HOTPLUG");
1929         else
1930                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1931 }
1932
1933 static int __init
1934 rcu_torture_init(void)
1935 {
1936         int i;
1937         int cpu;
1938         int firsterr = 0;
1939         int retval;
1940         static struct rcu_torture_ops *torture_ops[] =
1941                 { &rcu_ops, &rcu_sync_ops, &rcu_expedited_ops,
1942                   &rcu_bh_ops, &rcu_bh_sync_ops, &rcu_bh_expedited_ops,
1943                   &srcu_ops, &srcu_sync_ops, &srcu_expedited_ops,
1944                   &srcu_raw_ops, &srcu_raw_sync_ops,
1945                   &sched_ops, &sched_sync_ops, &sched_expedited_ops, };
1946
1947         mutex_lock(&fullstop_mutex);
1948
1949         /* Process args and tell the world that the torturer is on the job. */
1950         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1951                 cur_ops = torture_ops[i];
1952                 if (strcmp(torture_type, cur_ops->name) == 0)
1953                         break;
1954         }
1955         if (i == ARRAY_SIZE(torture_ops)) {
1956                 pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
1957                          torture_type);
1958                 pr_alert("rcu-torture types:");
1959                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1960                         pr_alert(" %s", torture_ops[i]->name);
1961                 pr_alert("\n");
1962                 mutex_unlock(&fullstop_mutex);
1963                 return -EINVAL;
1964         }
1965         if (cur_ops->fqs == NULL && fqs_duration != 0) {
1966                 pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
1967                 fqs_duration = 0;
1968         }
1969         if (cur_ops->init)
1970                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1971
1972         if (nreaders >= 0)
1973                 nrealreaders = nreaders;
1974         else
1975                 nrealreaders = 2 * num_online_cpus();
1976         rcu_torture_print_module_parms(cur_ops, "Start of test");
1977         fullstop = FULLSTOP_DONTSTOP;
1978
1979         /* Set up the freelist. */
1980
1981         INIT_LIST_HEAD(&rcu_torture_freelist);
1982         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1983                 rcu_tortures[i].rtort_mbtest = 0;
1984                 list_add_tail(&rcu_tortures[i].rtort_free,
1985                               &rcu_torture_freelist);
1986         }
1987
1988         /* Initialize the statistics so that each run gets its own numbers. */
1989
1990         rcu_torture_current = NULL;
1991         rcu_torture_current_version = 0;
1992         atomic_set(&n_rcu_torture_alloc, 0);
1993         atomic_set(&n_rcu_torture_alloc_fail, 0);
1994         atomic_set(&n_rcu_torture_free, 0);
1995         atomic_set(&n_rcu_torture_mberror, 0);
1996         atomic_set(&n_rcu_torture_error, 0);
1997         n_rcu_torture_barrier_error = 0;
1998         n_rcu_torture_boost_ktrerror = 0;
1999         n_rcu_torture_boost_rterror = 0;
2000         n_rcu_torture_boost_failure = 0;
2001         n_rcu_torture_boosts = 0;
2002         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
2003                 atomic_set(&rcu_torture_wcount[i], 0);
2004         for_each_possible_cpu(cpu) {
2005                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
2006                         per_cpu(rcu_torture_count, cpu)[i] = 0;
2007                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
2008                 }
2009         }
2010
2011         /* Start up the kthreads. */
2012
2013         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
2014         writer_task = kthread_create(rcu_torture_writer, NULL,
2015                                      "rcu_torture_writer");
2016         if (IS_ERR(writer_task)) {
2017                 firsterr = PTR_ERR(writer_task);
2018                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
2019                 writer_task = NULL;
2020                 goto unwind;
2021         }
2022         wake_up_process(writer_task);
2023         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
2024                                    GFP_KERNEL);
2025         if (fakewriter_tasks == NULL) {
2026                 VERBOSE_PRINTK_ERRSTRING("out of memory");
2027                 firsterr = -ENOMEM;
2028                 goto unwind;
2029         }
2030         for (i = 0; i < nfakewriters; i++) {
2031                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
2032                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
2033                                                   "rcu_torture_fakewriter");
2034                 if (IS_ERR(fakewriter_tasks[i])) {
2035                         firsterr = PTR_ERR(fakewriter_tasks[i]);
2036                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
2037                         fakewriter_tasks[i] = NULL;
2038                         goto unwind;
2039                 }
2040         }
2041         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
2042                                GFP_KERNEL);
2043         if (reader_tasks == NULL) {
2044                 VERBOSE_PRINTK_ERRSTRING("out of memory");
2045                 firsterr = -ENOMEM;
2046                 goto unwind;
2047         }
2048         for (i = 0; i < nrealreaders; i++) {
2049                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
2050                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
2051                                               "rcu_torture_reader");
2052                 if (IS_ERR(reader_tasks[i])) {
2053                         firsterr = PTR_ERR(reader_tasks[i]);
2054                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
2055                         reader_tasks[i] = NULL;
2056                         goto unwind;
2057                 }
2058         }
2059         if (stat_interval > 0) {
2060                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
2061                 stats_task = kthread_run(rcu_torture_stats, NULL,
2062                                         "rcu_torture_stats");
2063                 if (IS_ERR(stats_task)) {
2064                         firsterr = PTR_ERR(stats_task);
2065                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
2066                         stats_task = NULL;
2067                         goto unwind;
2068                 }
2069         }
2070         if (test_no_idle_hz) {
2071                 rcu_idle_cpu = num_online_cpus() - 1;
2072
2073                 if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
2074                         firsterr = -ENOMEM;
2075                         VERBOSE_PRINTK_ERRSTRING("Failed to alloc mask");
2076                         goto unwind;
2077                 }
2078
2079                 /* Create the shuffler thread */
2080                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
2081                                           "rcu_torture_shuffle");
2082                 if (IS_ERR(shuffler_task)) {
2083                         free_cpumask_var(shuffle_tmp_mask);
2084                         firsterr = PTR_ERR(shuffler_task);
2085                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
2086                         shuffler_task = NULL;
2087                         goto unwind;
2088                 }
2089         }
2090         if (stutter < 0)
2091                 stutter = 0;
2092         if (stutter) {
2093                 /* Create the stutter thread */
2094                 stutter_task = kthread_run(rcu_torture_stutter, NULL,
2095                                           "rcu_torture_stutter");
2096                 if (IS_ERR(stutter_task)) {
2097                         firsterr = PTR_ERR(stutter_task);
2098                         VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
2099                         stutter_task = NULL;
2100                         goto unwind;
2101                 }
2102         }
2103         if (fqs_duration < 0)
2104                 fqs_duration = 0;
2105         if (fqs_duration) {
2106                 /* Create the stutter thread */
2107                 fqs_task = kthread_run(rcu_torture_fqs, NULL,
2108                                        "rcu_torture_fqs");
2109                 if (IS_ERR(fqs_task)) {
2110                         firsterr = PTR_ERR(fqs_task);
2111                         VERBOSE_PRINTK_ERRSTRING("Failed to create fqs");
2112                         fqs_task = NULL;
2113                         goto unwind;
2114                 }
2115         }
2116         if (test_boost_interval < 1)
2117                 test_boost_interval = 1;
2118         if (test_boost_duration < 2)
2119                 test_boost_duration = 2;
2120         if ((test_boost == 1 && cur_ops->can_boost) ||
2121             test_boost == 2) {
2122
2123                 boost_starttime = jiffies + test_boost_interval * HZ;
2124                 register_cpu_notifier(&rcutorture_cpu_nb);
2125                 for_each_possible_cpu(i) {
2126                         if (cpu_is_offline(i))
2127                                 continue;  /* Heuristic: CPU can go offline. */
2128                         retval = rcutorture_booster_init(i);
2129                         if (retval < 0) {
2130                                 firsterr = retval;
2131                                 goto unwind;
2132                         }
2133                 }
2134         }
2135         if (shutdown_secs > 0) {
2136                 shutdown_time = jiffies + shutdown_secs * HZ;
2137                 shutdown_task = kthread_create(rcu_torture_shutdown, NULL,
2138                                                "rcu_torture_shutdown");
2139                 if (IS_ERR(shutdown_task)) {
2140                         firsterr = PTR_ERR(shutdown_task);
2141                         VERBOSE_PRINTK_ERRSTRING("Failed to create shutdown");
2142                         shutdown_task = NULL;
2143                         goto unwind;
2144                 }
2145                 wake_up_process(shutdown_task);
2146         }
2147         i = rcu_torture_onoff_init();
2148         if (i != 0) {
2149                 firsterr = i;
2150                 goto unwind;
2151         }
2152         register_reboot_notifier(&rcutorture_shutdown_nb);
2153         i = rcu_torture_stall_init();
2154         if (i != 0) {
2155                 firsterr = i;
2156                 goto unwind;
2157         }
2158         retval = rcu_torture_barrier_init();
2159         if (retval != 0) {
2160                 firsterr = retval;
2161                 goto unwind;
2162         }
2163         rcutorture_record_test_transition();
2164         mutex_unlock(&fullstop_mutex);
2165         return 0;
2166
2167 unwind:
2168         mutex_unlock(&fullstop_mutex);
2169         rcu_torture_cleanup();
2170         return firsterr;
2171 }
2172
2173 module_init(rcu_torture_init);
2174 module_exit(rcu_torture_cleanup);