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;       /* Interval between stats, in seconds. */
  57                                 /*  Defaults to "only at end of test". */
  58 static bool verbose;            /* Print more debug info. */
  59 static bool test_no_idle_hz;    /* Test RCU's support for tickless idle CPUs. */
  60 static int shuffle_interval = 3; /* Interval between shuffles (in sec)*/
  61 static int stutter = 5;         /* Start/stop testing interval (in sec) */
  62 static int irqreader = 1;       /* RCU readers from irq (timers). */
  63 static int fqs_duration;        /* Duration of bursts (us), 0 to disable. */
  64 static int fqs_holdoff;         /* Hold time within burst (us). */
  65 static int fqs_stutter = 3;     /* Wait time between bursts (s). */
  66 static int n_barrier_cbs;       /* Number of callbacks to test RCU barriers. */
  67 static int onoff_interval;      /* Wait time between CPU hotplugs, 0=disable. */
  68 static int onoff_holdoff;       /* Seconds after boot before CPU hotplugs. */
  69 static int shutdown_secs;       /* Shutdown time (s).  <=0 for no shutdown. */
  70 static int stall_cpu;           /* CPU-stall duration (s).  0 for no stall. */
  71 static int stall_cpu_holdoff = 10; /* Time to wait until stall (s).  */
  72 static int test_boost = 1;      /* Test RCU prio boost: 0=no, 1=maybe, 2=yes. */
  73 static int test_boost_interval = 7; /* Interval between boost tests, seconds. */
  74 static int test_boost_duration = 4; /* Duration of each boost test, seconds. */
  75 static char *torture_type = "rcu"; /* What RCU implementation to torture. */
  76
  77 module_param(nreaders, int, 0444);
  78 MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
  79 module_param(nfakewriters, int, 0444);
  80 MODULE_PARM_DESC(nfakewriters, "Number of RCU fake writer threads");
  81 module_param(stat_interval, int, 0644);
  82 MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
  83 module_param(verbose, bool, 0444);
  84 MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
  85 module_param(test_no_idle_hz, bool, 0444);
  86 MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
  87 module_param(shuffle_interval, int, 0444);
  88 MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
  89 module_param(stutter, int, 0444);
  90 MODULE_PARM_DESC(stutter, "Number of seconds to run/halt test");
  91 module_param(irqreader, int, 0444);
  92 MODULE_PARM_DESC(irqreader, "Allow RCU readers from irq handlers");
  93 module_param(fqs_duration, int, 0444);
  94 MODULE_PARM_DESC(fqs_duration, "Duration of fqs bursts (us)");
  95 module_param(fqs_holdoff, int, 0444);
  96 MODULE_PARM_DESC(fqs_holdoff, "Holdoff time within fqs bursts (us)");
  97 module_param(fqs_stutter, int, 0444);
  98 MODULE_PARM_DESC(fqs_stutter, "Wait time between fqs bursts (s)");
  99 module_param(n_barrier_cbs, int, 0444);
 100 MODULE_PARM_DESC(n_barrier_cbs, "# of callbacks/kthreads for barrier testing");
 101 module_param(onoff_interval, int, 0444);
 102 MODULE_PARM_DESC(onoff_interval, "Time between CPU hotplugs (s), 0=disable");
 103 module_param(onoff_holdoff, int, 0444);
 104 MODULE_PARM_DESC(onoff_holdoff, "Time after boot before CPU hotplugs (s)");
 105 module_param(shutdown_secs, int, 0444);
 106 MODULE_PARM_DESC(shutdown_secs, "Shutdown time (s), zero to disable.");
 107 module_param(stall_cpu, int, 0444);
 108 MODULE_PARM_DESC(stall_cpu, "Stall duration (s), zero to disable.");
 109 module_param(stall_cpu_holdoff, int, 0444);
 110 MODULE_PARM_DESC(stall_cpu_holdoff, "Time to wait before starting stall (s).");
 111 module_param(test_boost, int, 0444);
 112 MODULE_PARM_DESC(test_boost, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
 113 module_param(test_boost_interval, int, 0444);
 114 MODULE_PARM_DESC(test_boost_interval, "Interval between boost tests, seconds.");
 115 module_param(test_boost_duration, int, 0444);
 116 MODULE_PARM_DESC(test_boost_duration, "Duration of each boost test, seconds.");
 117 module_param(torture_type, charp, 0444);
 118 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, srcu)");
 119
 120 #define TORTURE_FLAG "-torture:"
 121 #define PRINTK_STRING(s) \
 122         do { printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
 123 #define VERBOSE_PRINTK_STRING(s) \
 124         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
 125 #define VERBOSE_PRINTK_ERRSTRING(s) \
 126         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
 127
 128 static char printk_buf[4096];
 129
 130 static int nrealreaders;
 131 static struct task_struct *writer_task;
 132 static struct task_struct **fakewriter_tasks;
 133 static struct task_struct **reader_tasks;
 134 static struct task_struct *stats_task;
 135 static struct task_struct *shuffler_task;
 136 static struct task_struct *stutter_task;
 137 static struct task_struct *fqs_task;
 138 static struct task_struct *boost_tasks[NR_CPUS];
 139 static struct task_struct *shutdown_task;
 140 #ifdef CONFIG_HOTPLUG_CPU
 141 static struct task_struct *onoff_task;
 142 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
 143 static struct task_struct *stall_task;
 144 static struct task_struct **barrier_cbs_tasks;
 145 static struct task_struct *barrier_task;
 146
 147 #define RCU_TORTURE_PIPE_LEN 10
 148
 149 struct rcu_torture {
 150         struct rcu_head rtort_rcu;
 151         int rtort_pipe_count;
 152         struct list_head rtort_free;
 153         int rtort_mbtest;
 154 };
 155
 156 static LIST_HEAD(rcu_torture_freelist);
 157 static struct rcu_torture __rcu *rcu_torture_current;
 158 static unsigned long rcu_torture_current_version;
 159 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 160 static DEFINE_SPINLOCK(rcu_torture_lock);
 161 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
 162         { 0 };
 163 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) =
 164         { 0 };
 165 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 166 static atomic_t n_rcu_torture_alloc;
 167 static atomic_t n_rcu_torture_alloc_fail;
 168 static atomic_t n_rcu_torture_free;
 169 static atomic_t n_rcu_torture_mberror;
 170 static atomic_t n_rcu_torture_error;
 171 static long n_rcu_torture_barrier_error;
 172 static long n_rcu_torture_boost_ktrerror;
 173 static long n_rcu_torture_boost_rterror;
 174 static long n_rcu_torture_boost_failure;
 175 static long n_rcu_torture_boosts;
 176 static long n_rcu_torture_timers;
 177 static long n_offline_attempts;
 178 static long n_offline_successes;
 179 static long n_online_attempts;
 180 static long n_online_successes;
 181 static long n_barrier_attempts;
 182 static long n_barrier_successes;
 183 static struct list_head rcu_torture_removed;
 184 static cpumask_var_t shuffle_tmp_mask;
 185
 186 static int stutter_pause_test;
 187
 188 #if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
 189 #define RCUTORTURE_RUNNABLE_INIT 1
 190 #else
 191 #define RCUTORTURE_RUNNABLE_INIT 0
 192 #endif
 193 int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT;
 194 module_param(rcutorture_runnable, int, 0444);
 195 MODULE_PARM_DESC(rcutorture_runnable, "Start rcutorture at boot");
 196
 197 #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
 198 #define rcu_can_boost() 1
 199 #else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 200 #define rcu_can_boost() 0
 201 #endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 202
 203 static unsigned long shutdown_time;     /* jiffies to system shutdown. */
 204 static unsigned long boost_starttime;   /* jiffies of next boost test start. */
 205 DEFINE_MUTEX(boost_mutex);              /* protect setting boost_starttime */
 206                                         /*  and boost task create/destroy. */
 207 static atomic_t barrier_cbs_count;      /* Barrier callbacks registered. */
 208 static bool barrier_phase;              /* Test phase. */
 209 static atomic_t barrier_cbs_invoked;    /* Barrier callbacks invoked. */
 210 static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */
 211 static DECLARE_WAIT_QUEUE_HEAD(barrier_wq);
 212
 213 /* Mediate rmmod and system shutdown.  Concurrent rmmod & shutdown illegal! */
 214
 215 #define FULLSTOP_DONTSTOP 0     /* Normal operation. */
 216 #define FULLSTOP_SHUTDOWN 1     /* System shutdown with rcutorture running. */
 217 #define FULLSTOP_RMMOD    2     /* Normal rmmod of rcutorture. */
 218 static int fullstop = FULLSTOP_RMMOD;
 219 /*
 220  * Protect fullstop transitions and spawning of kthreads.
 221  */
 222 static DEFINE_MUTEX(fullstop_mutex);
 223
 224 /* Forward reference. */
 225 static void rcu_torture_cleanup(void);
 226
 227 /*
 228  * Detect and respond to a system shutdown.
 229  */
 230 static int
 231 rcutorture_shutdown_notify(struct notifier_block *unused1,
 232                            unsigned long unused2, void *unused3)
 233 {
 234         mutex_lock(&fullstop_mutex);
 235         if (fullstop == FULLSTOP_DONTSTOP)
 236                 fullstop = FULLSTOP_SHUTDOWN;
 237         else
 238                 printk(KERN_WARNING /* but going down anyway, so... */
 239                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
 240         mutex_unlock(&fullstop_mutex);
 241         return NOTIFY_DONE;
 242 }
 243
 244 /*
 245  * Absorb kthreads into a kernel function that won't return, so that
 246  * they won't ever access module text or data again.
 247  */
 248 static void rcutorture_shutdown_absorb(char *title)
 249 {
 250         if (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
 251                 printk(KERN_NOTICE
 252                        "rcutorture thread %s parking due to system shutdown\n",
 253                        title);
 254                 schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
 255         }
 256 }
 257
 258 /*
 259  * Allocate an element from the rcu_tortures pool.
 260  */
 261 static struct rcu_torture *
 262 rcu_torture_alloc(void)
 263 {
 264         struct list_head *p;
 265
 266         spin_lock_bh(&rcu_torture_lock);
 267         if (list_empty(&rcu_torture_freelist)) {
 268                 atomic_inc(&n_rcu_torture_alloc_fail);
 269                 spin_unlock_bh(&rcu_torture_lock);
 270                 return NULL;
 271         }
 272         atomic_inc(&n_rcu_torture_alloc);
 273         p = rcu_torture_freelist.next;
 274         list_del_init(p);
 275         spin_unlock_bh(&rcu_torture_lock);
 276         return container_of(p, struct rcu_torture, rtort_free);
 277 }
 278
 279 /*
 280  * Free an element to the rcu_tortures pool.
 281  */
 282 static void
 283 rcu_torture_free(struct rcu_torture *p)
 284 {
 285         atomic_inc(&n_rcu_torture_free);
 286         spin_lock_bh(&rcu_torture_lock);
 287         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 288         spin_unlock_bh(&rcu_torture_lock);
 289 }
 290
 291 struct rcu_random_state {
 292         unsigned long rrs_state;
 293         long rrs_count;
 294 };
 295
 296 #define RCU_RANDOM_MULT 39916801  /* prime */
 297 #define RCU_RANDOM_ADD  479001701 /* prime */
 298 #define RCU_RANDOM_REFRESH 10000
 299
 300 #define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
 301
 302 /*
 303  * Crude but fast random-number generator.  Uses a linear congruential
 304  * generator, with occasional help from cpu_clock().
 305  */
 306 static unsigned long
 307 rcu_random(struct rcu_random_state *rrsp)
 308 {
 309         if (--rrsp->rrs_count < 0) {
 310                 rrsp->rrs_state += (unsigned long)local_clock();
 311                 rrsp->rrs_count = RCU_RANDOM_REFRESH;
 312         }
 313         rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
 314         return swahw32(rrsp->rrs_state);
 315 }
 316
 317 static void
 318 rcu_stutter_wait(char *title)
 319 {
 320         while (stutter_pause_test || !rcutorture_runnable) {
 321                 if (rcutorture_runnable)
 322                         schedule_timeout_interruptible(1);
 323                 else
 324                         schedule_timeout_interruptible(round_jiffies_relative(HZ));
 325                 rcutorture_shutdown_absorb(title);
 326         }
 327 }
 328
 329 /*
 330  * Operations vector for selecting different types of tests.
 331  */
 332
 333 struct rcu_torture_ops {
 334         void (*init)(void);
 335         void (*cleanup)(void);
 336         int (*readlock)(void);
 337         void (*read_delay)(struct rcu_random_state *rrsp);
 338         void (*readunlock)(int idx);
 339         int (*completed)(void);
 340         void (*deferred_free)(struct rcu_torture *p);
 341         void (*sync)(void);
 342         void (*call)(struct rcu_head *head, void (*func)(struct rcu_head *rcu));
 343         void (*cb_barrier)(void);
 344         void (*fqs)(void);
 345         int (*stats)(char *page);
 346         int irq_capable;
 347         int can_boost;
 348         char *name;
 349 };
 350
 351 static struct rcu_torture_ops *cur_ops;
 352
 353 /*
 354  * Definitions for rcu torture testing.
 355  */
 356
 357 static int rcu_torture_read_lock(void) __acquires(RCU)
 358 {
 359         rcu_read_lock();
 360         return 0;
 361 }
 362
 363 static void rcu_read_delay(struct rcu_random_state *rrsp)
 364 {
 365         const unsigned long shortdelay_us = 200;
 366         const unsigned long longdelay_ms = 50;
 367
 368         /* We want a short delay sometimes to make a reader delay the grace
 369          * period, and we want a long delay occasionally to trigger
 370          * force_quiescent_state. */
 371
 372         if (!(rcu_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
 373                 mdelay(longdelay_ms);
 374         if (!(rcu_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
 375                 udelay(shortdelay_us);
 376 #ifdef CONFIG_PREEMPT
 377         if (!preempt_count() && !(rcu_random(rrsp) % (nrealreaders * 20000)))
 378                 preempt_schedule();  /* No QS if preempt_disable() in effect */
 379 #endif
 380 }
 381
 382 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 383 {
 384         rcu_read_unlock();
 385 }
 386
 387 static int rcu_torture_completed(void)
 388 {
 389         return rcu_batches_completed();
 390 }
 391
 392 static void
 393 rcu_torture_cb(struct rcu_head *p)
 394 {
 395         int i;
 396         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 397
 398         if (fullstop != FULLSTOP_DONTSTOP) {
 399                 /* Test is ending, just drop callbacks on the floor. */
 400                 /* The next initialization will pick up the pieces. */
 401                 return;
 402         }
 403         i = rp->rtort_pipe_count;
 404         if (i > RCU_TORTURE_PIPE_LEN)
 405                 i = RCU_TORTURE_PIPE_LEN;
 406         atomic_inc(&rcu_torture_wcount[i]);
 407         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 408                 rp->rtort_mbtest = 0;
 409                 rcu_torture_free(rp);
 410         } else {
 411                 cur_ops->deferred_free(rp);
 412         }
 413 }
 414
 415 static int rcu_no_completed(void)
 416 {
 417         return 0;
 418 }
 419
 420 static void rcu_torture_deferred_free(struct rcu_torture *p)
 421 {
 422         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 423 }
 424
 425 static struct rcu_torture_ops rcu_ops = {
 426         .init           = NULL,
 427         .cleanup        = NULL,
 428         .readlock       = rcu_torture_read_lock,
 429         .read_delay     = rcu_read_delay,
 430         .readunlock     = rcu_torture_read_unlock,
 431         .completed      = rcu_torture_completed,
 432         .deferred_free  = rcu_torture_deferred_free,
 433         .sync           = synchronize_rcu,
 434         .call           = call_rcu,
 435         .cb_barrier     = rcu_barrier,
 436         .fqs            = rcu_force_quiescent_state,
 437         .stats          = NULL,
 438         .irq_capable    = 1,
 439         .can_boost      = rcu_can_boost(),
 440         .name           = "rcu"
 441 };
 442
 443 static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
 444 {
 445         int i;
 446         struct rcu_torture *rp;
 447         struct rcu_torture *rp1;
 448
 449         cur_ops->sync();
 450         list_add(&p->rtort_free, &rcu_torture_removed);
 451         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 452                 i = rp->rtort_pipe_count;
 453                 if (i > RCU_TORTURE_PIPE_LEN)
 454                         i = RCU_TORTURE_PIPE_LEN;
 455                 atomic_inc(&rcu_torture_wcount[i]);
 456                 if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 457                         rp->rtort_mbtest = 0;
 458                         list_del(&rp->rtort_free);
 459                         rcu_torture_free(rp);
 460                 }
 461         }
 462 }
 463
 464 static void rcu_sync_torture_init(void)
 465 {
 466         INIT_LIST_HEAD(&rcu_torture_removed);
 467 }
 468
 469 static struct rcu_torture_ops rcu_sync_ops = {
 470         .init           = rcu_sync_torture_init,
 471         .cleanup        = NULL,
 472         .readlock       = rcu_torture_read_lock,
 473         .read_delay     = rcu_read_delay,
 474         .readunlock     = rcu_torture_read_unlock,
 475         .completed      = rcu_torture_completed,
 476         .deferred_free  = rcu_sync_torture_deferred_free,
 477         .sync           = synchronize_rcu,
 478         .call           = NULL,
 479         .cb_barrier     = NULL,
 480         .fqs            = rcu_force_quiescent_state,
 481         .stats          = NULL,
 482         .irq_capable    = 1,
 483         .can_boost      = rcu_can_boost(),
 484         .name           = "rcu_sync"
 485 };
 486
 487 static struct rcu_torture_ops rcu_expedited_ops = {
 488         .init           = rcu_sync_torture_init,
 489         .cleanup        = NULL,
 490         .readlock       = rcu_torture_read_lock,
 491         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 492         .readunlock     = rcu_torture_read_unlock,
 493         .completed      = rcu_no_completed,
 494         .deferred_free  = rcu_sync_torture_deferred_free,
 495         .sync           = synchronize_rcu_expedited,
 496         .call           = NULL,
 497         .cb_barrier     = NULL,
 498         .fqs            = rcu_force_quiescent_state,
 499         .stats          = NULL,
 500         .irq_capable    = 1,
 501         .can_boost      = rcu_can_boost(),
 502         .name           = "rcu_expedited"
 503 };
 504
 505 /*
 506  * Definitions for rcu_bh torture testing.
 507  */
 508
 509 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
 510 {
 511         rcu_read_lock_bh();
 512         return 0;
 513 }
 514
 515 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
 516 {
 517         rcu_read_unlock_bh();
 518 }
 519
 520 static int rcu_bh_torture_completed(void)
 521 {
 522         return rcu_batches_completed_bh();
 523 }
 524
 525 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 526 {
 527         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
 528 }
 529
 530 static struct rcu_torture_ops rcu_bh_ops = {
 531         .init           = NULL,
 532         .cleanup        = NULL,
 533         .readlock       = rcu_bh_torture_read_lock,
 534         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 535         .readunlock     = rcu_bh_torture_read_unlock,
 536         .completed      = rcu_bh_torture_completed,
 537         .deferred_free  = rcu_bh_torture_deferred_free,
 538         .sync           = synchronize_rcu_bh,
 539         .call           = call_rcu_bh,
 540         .cb_barrier     = rcu_barrier_bh,
 541         .fqs            = rcu_bh_force_quiescent_state,
 542         .stats          = NULL,
 543         .irq_capable    = 1,
 544         .name           = "rcu_bh"
 545 };
 546
 547 static struct rcu_torture_ops rcu_bh_sync_ops = {
 548         .init           = rcu_sync_torture_init,
 549         .cleanup        = NULL,
 550         .readlock       = rcu_bh_torture_read_lock,
 551         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 552         .readunlock     = rcu_bh_torture_read_unlock,
 553         .completed      = rcu_bh_torture_completed,
 554         .deferred_free  = rcu_sync_torture_deferred_free,
 555         .sync           = synchronize_rcu_bh,
 556         .call           = NULL,
 557         .cb_barrier     = NULL,
 558         .fqs            = rcu_bh_force_quiescent_state,
 559         .stats          = NULL,
 560         .irq_capable    = 1,
 561         .name           = "rcu_bh_sync"
 562 };
 563
 564 static struct rcu_torture_ops rcu_bh_expedited_ops = {
 565         .init           = rcu_sync_torture_init,
 566         .cleanup        = NULL,
 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 static struct srcu_struct srcu_ctl;
 586
 587 static void srcu_torture_init(void)
 588 {
 589         init_srcu_struct(&srcu_ctl);
 590         rcu_sync_torture_init();
 591 }
 592
 593 static void srcu_torture_cleanup(void)
 594 {
 595         synchronize_srcu(&srcu_ctl);
 596         cleanup_srcu_struct(&srcu_ctl);
 597 }
 598
 599 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
 600 {
 601         return srcu_read_lock(&srcu_ctl);
 602 }
 603
 604 static void srcu_read_delay(struct rcu_random_state *rrsp)
 605 {
 606         long delay;
 607         const long uspertick = 1000000 / HZ;
 608         const long longdelay = 10;
 609
 610         /* We want there to be long-running readers, but not all the time. */
 611
 612         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
 613         if (!delay)
 614                 schedule_timeout_interruptible(longdelay);
 615         else
 616                 rcu_read_delay(rrsp);
 617 }
 618
 619 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
 620 {
 621         srcu_read_unlock(&srcu_ctl, idx);
 622 }
 623
 624 static int srcu_torture_completed(void)
 625 {
 626         return srcu_batches_completed(&srcu_ctl);
 627 }
 628
 629 static void srcu_torture_deferred_free(struct rcu_torture *rp)
 630 {
 631         call_srcu(&srcu_ctl, &rp->rtort_rcu, rcu_torture_cb);
 632 }
 633
 634 static void srcu_torture_synchronize(void)
 635 {
 636         synchronize_srcu(&srcu_ctl);
 637 }
 638
 639 static void srcu_torture_call(struct rcu_head *head,
 640                               void (*func)(struct rcu_head *head))
 641 {
 642         call_srcu(&srcu_ctl, head, func);
 643 }
 644
 645 static void srcu_torture_barrier(void)
 646 {
 647         srcu_barrier(&srcu_ctl);
 648 }
 649
 650 static int srcu_torture_stats(char *page)
 651 {
 652         int cnt = 0;
 653         int cpu;
 654         int idx = srcu_ctl.completed & 0x1;
 655
 656         cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
 657                        torture_type, TORTURE_FLAG, idx);
 658         for_each_possible_cpu(cpu) {
 659                 cnt += sprintf(&page[cnt], " %d(%lu,%lu)", cpu,
 660                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
 661                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
 662         }
 663         cnt += sprintf(&page[cnt], "\n");
 664         return cnt;
 665 }
 666
 667 static struct rcu_torture_ops srcu_ops = {
 668         .init           = srcu_torture_init,
 669         .cleanup        = srcu_torture_cleanup,
 670         .readlock       = srcu_torture_read_lock,
 671         .read_delay     = srcu_read_delay,
 672         .readunlock     = srcu_torture_read_unlock,
 673         .completed      = srcu_torture_completed,
 674         .deferred_free  = srcu_torture_deferred_free,
 675         .sync           = srcu_torture_synchronize,
 676         .call           = srcu_torture_call,
 677         .cb_barrier     = srcu_torture_barrier,
 678         .stats          = srcu_torture_stats,
 679         .name           = "srcu"
 680 };
 681
 682 static struct rcu_torture_ops srcu_sync_ops = {
 683         .init           = srcu_torture_init,
 684         .cleanup        = srcu_torture_cleanup,
 685         .readlock       = srcu_torture_read_lock,
 686         .read_delay     = srcu_read_delay,
 687         .readunlock     = srcu_torture_read_unlock,
 688         .completed      = srcu_torture_completed,
 689         .deferred_free  = rcu_sync_torture_deferred_free,
 690         .sync           = srcu_torture_synchronize,
 691         .call           = NULL,
 692         .cb_barrier     = NULL,
 693         .stats          = srcu_torture_stats,
 694         .name           = "srcu_sync"
 695 };
 696
 697 static int srcu_torture_read_lock_raw(void) __acquires(&srcu_ctl)
 698 {
 699         return srcu_read_lock_raw(&srcu_ctl);
 700 }
 701
 702 static void srcu_torture_read_unlock_raw(int idx) __releases(&srcu_ctl)
 703 {
 704         srcu_read_unlock_raw(&srcu_ctl, idx);
 705 }
 706
 707 static struct rcu_torture_ops srcu_raw_ops = {
 708         .init           = srcu_torture_init,
 709         .cleanup        = srcu_torture_cleanup,
 710         .readlock       = srcu_torture_read_lock_raw,
 711         .read_delay     = srcu_read_delay,
 712         .readunlock     = srcu_torture_read_unlock_raw,
 713         .completed      = srcu_torture_completed,
 714         .deferred_free  = srcu_torture_deferred_free,
 715         .sync           = srcu_torture_synchronize,
 716         .call           = NULL,
 717         .cb_barrier     = NULL,
 718         .stats          = srcu_torture_stats,
 719         .name           = "srcu_raw"
 720 };
 721
 722 static struct rcu_torture_ops srcu_raw_sync_ops = {
 723         .init           = srcu_torture_init,
 724         .cleanup        = srcu_torture_cleanup,
 725         .readlock       = srcu_torture_read_lock_raw,
 726         .read_delay     = srcu_read_delay,
 727         .readunlock     = srcu_torture_read_unlock_raw,
 728         .completed      = srcu_torture_completed,
 729         .deferred_free  = rcu_sync_torture_deferred_free,
 730         .sync           = srcu_torture_synchronize,
 731         .call           = NULL,
 732         .cb_barrier     = NULL,
 733         .stats          = srcu_torture_stats,
 734         .name           = "srcu_raw_sync"
 735 };
 736
 737 static void srcu_torture_synchronize_expedited(void)
 738 {
 739         synchronize_srcu_expedited(&srcu_ctl);
 740 }
 741
 742 static struct rcu_torture_ops srcu_expedited_ops = {
 743         .init           = srcu_torture_init,
 744         .cleanup        = srcu_torture_cleanup,
 745         .readlock       = srcu_torture_read_lock,
 746         .read_delay     = srcu_read_delay,
 747         .readunlock     = srcu_torture_read_unlock,
 748         .completed      = srcu_torture_completed,
 749         .deferred_free  = rcu_sync_torture_deferred_free,
 750         .sync           = srcu_torture_synchronize_expedited,
 751         .call           = NULL,
 752         .cb_barrier     = NULL,
 753         .stats          = srcu_torture_stats,
 754         .name           = "srcu_expedited"
 755 };
 756
 757 /*
 758  * Definitions for sched torture testing.
 759  */
 760
 761 static int sched_torture_read_lock(void)
 762 {
 763         preempt_disable();
 764         return 0;
 765 }
 766
 767 static void sched_torture_read_unlock(int idx)
 768 {
 769         preempt_enable();
 770 }
 771
 772 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
 773 {
 774         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
 775 }
 776
 777 static struct rcu_torture_ops sched_ops = {
 778         .init           = rcu_sync_torture_init,
 779         .cleanup        = NULL,
 780         .readlock       = sched_torture_read_lock,
 781         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 782         .readunlock     = sched_torture_read_unlock,
 783         .completed      = rcu_no_completed,
 784         .deferred_free  = rcu_sched_torture_deferred_free,
 785         .sync           = synchronize_sched,
 786         .cb_barrier     = rcu_barrier_sched,
 787         .fqs            = rcu_sched_force_quiescent_state,
 788         .stats          = NULL,
 789         .irq_capable    = 1,
 790         .name           = "sched"
 791 };
 792
 793 static struct rcu_torture_ops sched_sync_ops = {
 794         .init           = rcu_sync_torture_init,
 795         .cleanup        = NULL,
 796         .readlock       = sched_torture_read_lock,
 797         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 798         .readunlock     = sched_torture_read_unlock,
 799         .completed      = rcu_no_completed,
 800         .deferred_free  = rcu_sync_torture_deferred_free,
 801         .sync           = synchronize_sched,
 802         .cb_barrier     = NULL,
 803         .fqs            = rcu_sched_force_quiescent_state,
 804         .stats          = NULL,
 805         .name           = "sched_sync"
 806 };
 807
 808 static struct rcu_torture_ops sched_expedited_ops = {
 809         .init           = rcu_sync_torture_init,
 810         .cleanup        = NULL,
 811         .readlock       = sched_torture_read_lock,
 812         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 813         .readunlock     = sched_torture_read_unlock,
 814         .completed      = rcu_no_completed,
 815         .deferred_free  = rcu_sync_torture_deferred_free,
 816         .sync           = synchronize_sched_expedited,
 817         .cb_barrier     = NULL,
 818         .fqs            = rcu_sched_force_quiescent_state,
 819         .stats          = NULL,
 820         .irq_capable    = 1,
 821         .name           = "sched_expedited"
 822 };
 823
 824 /*
 825  * RCU torture priority-boost testing.  Runs one real-time thread per
 826  * CPU for moderate bursts, repeatedly registering RCU callbacks and
 827  * spinning waiting for them to be invoked.  If a given callback takes
 828  * too long to be invoked, we assume that priority inversion has occurred.
 829  */
 830
 831 struct rcu_boost_inflight {
 832         struct rcu_head rcu;
 833         int inflight;
 834 };
 835
 836 static void rcu_torture_boost_cb(struct rcu_head *head)
 837 {
 838         struct rcu_boost_inflight *rbip =
 839                 container_of(head, struct rcu_boost_inflight, rcu);
 840
 841         smp_mb(); /* Ensure RCU-core accesses precede clearing ->inflight */
 842         rbip->inflight = 0;
 843 }
 844
 845 static int rcu_torture_boost(void *arg)
 846 {
 847         unsigned long call_rcu_time;
 848         unsigned long endtime;
 849         unsigned long oldstarttime;
 850         struct rcu_boost_inflight rbi = { .inflight = 0 };
 851         struct sched_param sp;
 852
 853         VERBOSE_PRINTK_STRING("rcu_torture_boost started");
 854
 855         /* Set real-time priority. */
 856         sp.sched_priority = 1;
 857         if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 858                 VERBOSE_PRINTK_STRING("rcu_torture_boost RT prio failed!");
 859                 n_rcu_torture_boost_rterror++;
 860         }
 861
 862         init_rcu_head_on_stack(&rbi.rcu);
 863         /* Each pass through the following loop does one boost-test cycle. */
 864         do {
 865                 /* Wait for the next test interval. */
 866                 oldstarttime = boost_starttime;
 867                 while (ULONG_CMP_LT(jiffies, oldstarttime)) {
 868                         schedule_timeout_uninterruptible(1);
 869                         rcu_stutter_wait("rcu_torture_boost");
 870                         if (kthread_should_stop() ||
 871                             fullstop != FULLSTOP_DONTSTOP)
 872                                 goto checkwait;
 873                 }
 874
 875                 /* Do one boost-test interval. */
 876                 endtime = oldstarttime + test_boost_duration * HZ;
 877                 call_rcu_time = jiffies;
 878                 while (ULONG_CMP_LT(jiffies, endtime)) {
 879                         /* If we don't have a callback in flight, post one. */
 880                         if (!rbi.inflight) {
 881                                 smp_mb(); /* RCU core before ->inflight = 1. */
 882                                 rbi.inflight = 1;
 883                                 call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 884                                 if (jiffies - call_rcu_time >
 885                                          test_boost_duration * HZ - HZ / 2) {
 886                                         VERBOSE_PRINTK_STRING("rcu_torture_boost boosting failed");
 887                                         n_rcu_torture_boost_failure++;
 888                                 }
 889                                 call_rcu_time = jiffies;
 890                         }
 891                         cond_resched();
 892                         rcu_stutter_wait("rcu_torture_boost");
 893                         if (kthread_should_stop() ||
 894                             fullstop != FULLSTOP_DONTSTOP)
 895                                 goto checkwait;
 896                 }
 897
 898                 /*
 899                  * Set the start time of the next test interval.
 900                  * Yes, this is vulnerable to long delays, but such
 901                  * delays simply cause a false negative for the next
 902                  * interval.  Besides, we are running at RT priority,
 903                  * so delays should be relatively rare.
 904                  */
 905                 while (oldstarttime == boost_starttime &&
 906                        !kthread_should_stop()) {
 907                         if (mutex_trylock(&boost_mutex)) {
 908                                 boost_starttime = jiffies +
 909                                                   test_boost_interval * HZ;
 910                                 n_rcu_torture_boosts++;
 911                                 mutex_unlock(&boost_mutex);
 912                                 break;
 913                         }
 914                         schedule_timeout_uninterruptible(1);
 915                 }
 916
 917                 /* Go do the stutter. */
 918 checkwait:      rcu_stutter_wait("rcu_torture_boost");
 919         } while (!kthread_should_stop() && fullstop  == FULLSTOP_DONTSTOP);
 920
 921         /* Clean up and exit. */
 922         VERBOSE_PRINTK_STRING("rcu_torture_boost task stopping");
 923         rcutorture_shutdown_absorb("rcu_torture_boost");
 924         while (!kthread_should_stop() || rbi.inflight)
 925                 schedule_timeout_uninterruptible(1);
 926         smp_mb(); /* order accesses to ->inflight before stack-frame death. */
 927         destroy_rcu_head_on_stack(&rbi.rcu);
 928         return 0;
 929 }
 930
 931 /*
 932  * RCU torture force-quiescent-state kthread.  Repeatedly induces
 933  * bursts of calls to force_quiescent_state(), increasing the probability
 934  * of occurrence of some important types of race conditions.
 935  */
 936 static int
 937 rcu_torture_fqs(void *arg)
 938 {
 939         unsigned long fqs_resume_time;
 940         int fqs_burst_remaining;
 941
 942         VERBOSE_PRINTK_STRING("rcu_torture_fqs task started");
 943         do {
 944                 fqs_resume_time = jiffies + fqs_stutter * HZ;
 945                 while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
 946                        !kthread_should_stop()) {
 947                         schedule_timeout_interruptible(1);
 948                 }
 949                 fqs_burst_remaining = fqs_duration;
 950                 while (fqs_burst_remaining > 0 &&
 951                        !kthread_should_stop()) {
 952                         cur_ops->fqs();
 953                         udelay(fqs_holdoff);
 954                         fqs_burst_remaining -= fqs_holdoff;
 955                 }
 956                 rcu_stutter_wait("rcu_torture_fqs");
 957         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 958         VERBOSE_PRINTK_STRING("rcu_torture_fqs task stopping");
 959         rcutorture_shutdown_absorb("rcu_torture_fqs");
 960         while (!kthread_should_stop())
 961                 schedule_timeout_uninterruptible(1);
 962         return 0;
 963 }
 964
 965 /*
 966  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 967  * for that pointed to by rcu_torture_current, freeing the old structure
 968  * after a series of grace periods (the "pipeline").
 969  */
 970 static int
 971 rcu_torture_writer(void *arg)
 972 {
 973         int i;
 974         long oldbatch = rcu_batches_completed();
 975         struct rcu_torture *rp;
 976         struct rcu_torture *old_rp;
 977         static DEFINE_RCU_RANDOM(rand);
 978
 979         VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
 980         set_user_nice(current, 19);
 981
 982         do {
 983                 schedule_timeout_uninterruptible(1);
 984                 rp = rcu_torture_alloc();
 985                 if (rp == NULL)
 986                         continue;
 987                 rp->rtort_pipe_count = 0;
 988                 udelay(rcu_random(&rand) & 0x3ff);
 989                 old_rp = rcu_dereference_check(rcu_torture_current,
 990                                                current == writer_task);
 991                 rp->rtort_mbtest = 1;
 992                 rcu_assign_pointer(rcu_torture_current, rp);
 993                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
 994                 if (old_rp) {
 995                         i = old_rp->rtort_pipe_count;
 996                         if (i > RCU_TORTURE_PIPE_LEN)
 997                                 i = RCU_TORTURE_PIPE_LEN;
 998                         atomic_inc(&rcu_torture_wcount[i]);
 999                         old_rp->rtort_pipe_count++;
1000                         cur_ops->deferred_free(old_rp);
1001                 }
1002                 rcutorture_record_progress(++rcu_torture_current_version);
1003                 oldbatch = cur_ops->completed();
1004                 rcu_stutter_wait("rcu_torture_writer");
1005         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1006         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
1007         rcutorture_shutdown_absorb("rcu_torture_writer");
1008         while (!kthread_should_stop())
1009                 schedule_timeout_uninterruptible(1);
1010         return 0;
1011 }
1012
1013 /*
1014  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
1015  * delay between calls.
1016  */
1017 static int
1018 rcu_torture_fakewriter(void *arg)
1019 {
1020         DEFINE_RCU_RANDOM(rand);
1021
1022         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
1023         set_user_nice(current, 19);
1024
1025         do {
1026                 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
1027                 udelay(rcu_random(&rand) & 0x3ff);
1028                 if (cur_ops->cb_barrier != NULL &&
1029                     rcu_random(&rand) % (nfakewriters * 8) == 0)
1030                         cur_ops->cb_barrier();
1031                 else
1032                         cur_ops->sync();
1033                 rcu_stutter_wait("rcu_torture_fakewriter");
1034         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1035
1036         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
1037         rcutorture_shutdown_absorb("rcu_torture_fakewriter");
1038         while (!kthread_should_stop())
1039                 schedule_timeout_uninterruptible(1);
1040         return 0;
1041 }
1042
1043 void rcutorture_trace_dump(void)
1044 {
1045         static atomic_t beenhere = ATOMIC_INIT(0);
1046
1047         if (atomic_read(&beenhere))
1048                 return;
1049         if (atomic_xchg(&beenhere, 1) != 0)
1050                 return;
1051         do_trace_rcu_torture_read(cur_ops->name, (struct rcu_head *)~0UL);
1052         ftrace_dump(DUMP_ALL);
1053 }
1054
1055 /*
1056  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
1057  * incrementing the corresponding element of the pipeline array.  The
1058  * counter in the element should never be greater than 1, otherwise, the
1059  * RCU implementation is broken.
1060  */
1061 static void rcu_torture_timer(unsigned long unused)
1062 {
1063         int idx;
1064         int completed;
1065         static DEFINE_RCU_RANDOM(rand);
1066         static DEFINE_SPINLOCK(rand_lock);
1067         struct rcu_torture *p;
1068         int pipe_count;
1069
1070         idx = cur_ops->readlock();
1071         completed = cur_ops->completed();
1072         p = rcu_dereference_check(rcu_torture_current,
1073                                   rcu_read_lock_bh_held() ||
1074                                   rcu_read_lock_sched_held() ||
1075                                   srcu_read_lock_held(&srcu_ctl));
1076         if (p == NULL) {
1077                 /* Leave because rcu_torture_writer is not yet underway */
1078                 cur_ops->readunlock(idx);
1079                 return;
1080         }
1081         do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu);
1082         if (p->rtort_mbtest == 0)
1083                 atomic_inc(&n_rcu_torture_mberror);
1084         spin_lock(&rand_lock);
1085         cur_ops->read_delay(&rand);
1086         n_rcu_torture_timers++;
1087         spin_unlock(&rand_lock);
1088         preempt_disable();
1089         pipe_count = p->rtort_pipe_count;
1090         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1091                 /* Should not happen, but... */
1092                 pipe_count = RCU_TORTURE_PIPE_LEN;
1093         }
1094         if (pipe_count > 1)
1095                 rcutorture_trace_dump();
1096         __this_cpu_inc(rcu_torture_count[pipe_count]);
1097         completed = cur_ops->completed() - completed;
1098         if (completed > RCU_TORTURE_PIPE_LEN) {
1099                 /* Should not happen, but... */
1100                 completed = RCU_TORTURE_PIPE_LEN;
1101         }
1102         __this_cpu_inc(rcu_torture_batch[completed]);
1103         preempt_enable();
1104         cur_ops->readunlock(idx);
1105 }
1106
1107 /*
1108  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
1109  * incrementing the corresponding element of the pipeline array.  The
1110  * counter in the element should never be greater than 1, otherwise, the
1111  * RCU implementation is broken.
1112  */
1113 static int
1114 rcu_torture_reader(void *arg)
1115 {
1116         int completed;
1117         int idx;
1118         DEFINE_RCU_RANDOM(rand);
1119         struct rcu_torture *p;
1120         int pipe_count;
1121         struct timer_list t;
1122
1123         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
1124         set_user_nice(current, 19);
1125         if (irqreader && cur_ops->irq_capable)
1126                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
1127
1128         do {
1129                 if (irqreader && cur_ops->irq_capable) {
1130                         if (!timer_pending(&t))
1131                                 mod_timer(&t, jiffies + 1);
1132                 }
1133                 idx = cur_ops->readlock();
1134                 completed = cur_ops->completed();
1135                 p = rcu_dereference_check(rcu_torture_current,
1136                                           rcu_read_lock_bh_held() ||
1137                                           rcu_read_lock_sched_held() ||
1138                                           srcu_read_lock_held(&srcu_ctl));
1139                 if (p == NULL) {
1140                         /* Wait for rcu_torture_writer to get underway */
1141                         cur_ops->readunlock(idx);
1142                         schedule_timeout_interruptible(HZ);
1143                         continue;
1144                 }
1145                 do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu);
1146                 if (p->rtort_mbtest == 0)
1147                         atomic_inc(&n_rcu_torture_mberror);
1148                 cur_ops->read_delay(&rand);
1149                 preempt_disable();
1150                 pipe_count = p->rtort_pipe_count;
1151                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1152                         /* Should not happen, but... */
1153                         pipe_count = RCU_TORTURE_PIPE_LEN;
1154                 }
1155                 if (pipe_count > 1)
1156                         rcutorture_trace_dump();
1157                 __this_cpu_inc(rcu_torture_count[pipe_count]);
1158                 completed = cur_ops->completed() - completed;
1159                 if (completed > RCU_TORTURE_PIPE_LEN) {
1160                         /* Should not happen, but... */
1161                         completed = RCU_TORTURE_PIPE_LEN;
1162                 }
1163                 __this_cpu_inc(rcu_torture_batch[completed]);
1164                 preempt_enable();
1165                 cur_ops->readunlock(idx);
1166                 schedule();
1167                 rcu_stutter_wait("rcu_torture_reader");
1168         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1169         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
1170         rcutorture_shutdown_absorb("rcu_torture_reader");
1171         if (irqreader && cur_ops->irq_capable)
1172                 del_timer_sync(&t);
1173         while (!kthread_should_stop())
1174                 schedule_timeout_uninterruptible(1);
1175         return 0;
1176 }
1177
1178 /*
1179  * Create an RCU-torture statistics message in the specified buffer.
1180  */
1181 static int
1182 rcu_torture_printk(char *page)
1183 {
1184         int cnt = 0;
1185         int cpu;
1186         int i;
1187         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1188         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1189
1190         for_each_possible_cpu(cpu) {
1191                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1192                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1193                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1194                 }
1195         }
1196         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1197                 if (pipesummary[i] != 0)
1198                         break;
1199         }
1200         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
1201         cnt += sprintf(&page[cnt],
1202                        "rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
1203                        rcu_torture_current,
1204                        rcu_torture_current_version,
1205                        list_empty(&rcu_torture_freelist),
1206                        atomic_read(&n_rcu_torture_alloc),
1207                        atomic_read(&n_rcu_torture_alloc_fail),
1208                        atomic_read(&n_rcu_torture_free));
1209         cnt += sprintf(&page[cnt], "rtmbe: %d rtbke: %ld rtbre: %ld ",
1210                        atomic_read(&n_rcu_torture_mberror),
1211                        n_rcu_torture_boost_ktrerror,
1212                        n_rcu_torture_boost_rterror);
1213         cnt += sprintf(&page[cnt], "rtbf: %ld rtb: %ld nt: %ld ",
1214                        n_rcu_torture_boost_failure,
1215                        n_rcu_torture_boosts,
1216                        n_rcu_torture_timers);
1217         cnt += sprintf(&page[cnt], "onoff: %ld/%ld:%ld/%ld ",
1218                        n_online_successes,
1219                        n_online_attempts,
1220                        n_offline_successes,
1221                        n_offline_attempts);
1222         cnt += sprintf(&page[cnt], "barrier: %ld/%ld:%ld",
1223                        n_barrier_successes,
1224                        n_barrier_attempts,
1225                        n_rcu_torture_barrier_error);
1226         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1227         if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1228             n_rcu_torture_barrier_error != 0 ||
1229             n_rcu_torture_boost_ktrerror != 0 ||
1230             n_rcu_torture_boost_rterror != 0 ||
1231             n_rcu_torture_boost_failure != 0 ||
1232             i > 1) {
1233                 cnt += sprintf(&page[cnt], "!!! ");
1234                 atomic_inc(&n_rcu_torture_error);
1235                 WARN_ON_ONCE(1);
1236         }
1237         cnt += sprintf(&page[cnt], "Reader Pipe: ");
1238         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1239                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
1240         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1241         cnt += sprintf(&page[cnt], "Reader Batch: ");
1242         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1243                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
1244         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1245         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
1246         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1247                 cnt += sprintf(&page[cnt], " %d",
1248                                atomic_read(&rcu_torture_wcount[i]));
1249         }
1250         cnt += sprintf(&page[cnt], "\n");
1251         if (cur_ops->stats)
1252                 cnt += cur_ops->stats(&page[cnt]);
1253         return cnt;
1254 }
1255
1256 /*
1257  * Print torture statistics.  Caller must ensure that there is only
1258  * one call to this function at a given time!!!  This is normally
1259  * accomplished by relying on the module system to only have one copy
1260  * of the module loaded, and then by giving the rcu_torture_stats
1261  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1262  * thread is not running).
1263  */
1264 static void
1265 rcu_torture_stats_print(void)
1266 {
1267         int cnt;
1268
1269         cnt = rcu_torture_printk(printk_buf);
1270         printk(KERN_ALERT "%s", printk_buf);
1271 }
1272
1273 /*
1274  * Periodically prints torture statistics, if periodic statistics printing
1275  * was specified via the stat_interval module parameter.
1276  *
1277  * No need to worry about fullstop here, since this one doesn't reference
1278  * volatile state or register callbacks.
1279  */
1280 static int
1281 rcu_torture_stats(void *arg)
1282 {
1283         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
1284         do {
1285                 schedule_timeout_interruptible(stat_interval * HZ);
1286                 rcu_torture_stats_print();
1287                 rcutorture_shutdown_absorb("rcu_torture_stats");
1288         } while (!kthread_should_stop());
1289         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
1290         return 0;
1291 }
1292
1293 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
1294
1295 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
1296  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
1297  */
1298 static void rcu_torture_shuffle_tasks(void)
1299 {
1300         int i;
1301
1302         cpumask_setall(shuffle_tmp_mask);
1303         get_online_cpus();
1304
1305         /* No point in shuffling if there is only one online CPU (ex: UP) */
1306         if (num_online_cpus() == 1) {
1307                 put_online_cpus();
1308                 return;
1309         }
1310
1311         if (rcu_idle_cpu != -1)
1312                 cpumask_clear_cpu(rcu_idle_cpu, shuffle_tmp_mask);
1313
1314         set_cpus_allowed_ptr(current, shuffle_tmp_mask);
1315
1316         if (reader_tasks) {
1317                 for (i = 0; i < nrealreaders; i++)
1318                         if (reader_tasks[i])
1319                                 set_cpus_allowed_ptr(reader_tasks[i],
1320                                                      shuffle_tmp_mask);
1321         }
1322
1323         if (fakewriter_tasks) {
1324                 for (i = 0; i < nfakewriters; i++)
1325                         if (fakewriter_tasks[i])
1326                                 set_cpus_allowed_ptr(fakewriter_tasks[i],
1327                                                      shuffle_tmp_mask);
1328         }
1329
1330         if (writer_task)
1331                 set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
1332
1333         if (stats_task)
1334                 set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
1335
1336         if (rcu_idle_cpu == -1)
1337                 rcu_idle_cpu = num_online_cpus() - 1;
1338         else
1339                 rcu_idle_cpu--;
1340
1341         put_online_cpus();
1342 }
1343
1344 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
1345  * system to become idle at a time and cut off its timer ticks. This is meant
1346  * to test the support for such tickless idle CPU in RCU.
1347  */
1348 static int
1349 rcu_torture_shuffle(void *arg)
1350 {
1351         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
1352         do {
1353                 schedule_timeout_interruptible(shuffle_interval * HZ);
1354                 rcu_torture_shuffle_tasks();
1355                 rcutorture_shutdown_absorb("rcu_torture_shuffle");
1356         } while (!kthread_should_stop());
1357         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
1358         return 0;
1359 }
1360
1361 /* Cause the rcutorture test to "stutter", starting and stopping all
1362  * threads periodically.
1363  */
1364 static int
1365 rcu_torture_stutter(void *arg)
1366 {
1367         VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
1368         do {
1369                 schedule_timeout_interruptible(stutter * HZ);
1370                 stutter_pause_test = 1;
1371                 if (!kthread_should_stop())
1372                         schedule_timeout_interruptible(stutter * HZ);
1373                 stutter_pause_test = 0;
1374                 rcutorture_shutdown_absorb("rcu_torture_stutter");
1375         } while (!kthread_should_stop());
1376         VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
1377         return 0;
1378 }
1379
1380 static inline void
1381 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, char *tag)
1382 {
1383         printk(KERN_ALERT "%s" TORTURE_FLAG
1384                 "--- %s: nreaders=%d nfakewriters=%d "
1385                 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1386                 "shuffle_interval=%d stutter=%d irqreader=%d "
1387                 "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1388                 "test_boost=%d/%d test_boost_interval=%d "
1389                 "test_boost_duration=%d shutdown_secs=%d "
1390                 "onoff_interval=%d onoff_holdoff=%d\n",
1391                 torture_type, tag, nrealreaders, nfakewriters,
1392                 stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1393                 stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1394                 test_boost, cur_ops->can_boost,
1395                 test_boost_interval, test_boost_duration, shutdown_secs,
1396                 onoff_interval, onoff_holdoff);
1397 }
1398
1399 static struct notifier_block rcutorture_shutdown_nb = {
1400         .notifier_call = rcutorture_shutdown_notify,
1401 };
1402
1403 static void rcutorture_booster_cleanup(int cpu)
1404 {
1405         struct task_struct *t;
1406
1407         if (boost_tasks[cpu] == NULL)
1408                 return;
1409         mutex_lock(&boost_mutex);
1410         VERBOSE_PRINTK_STRING("Stopping rcu_torture_boost task");
1411         t = boost_tasks[cpu];
1412         boost_tasks[cpu] = NULL;
1413         mutex_unlock(&boost_mutex);
1414
1415         /* This must be outside of the mutex, otherwise deadlock! */
1416         kthread_stop(t);
1417         boost_tasks[cpu] = NULL;
1418 }
1419
1420 static int rcutorture_booster_init(int cpu)
1421 {
1422         int retval;
1423
1424         if (boost_tasks[cpu] != NULL)
1425                 return 0;  /* Already created, nothing more to do. */
1426
1427         /* Don't allow time recalculation while creating a new task. */
1428         mutex_lock(&boost_mutex);
1429         VERBOSE_PRINTK_STRING("Creating rcu_torture_boost task");
1430         boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1431                                                   cpu_to_node(cpu),
1432                                                   "rcu_torture_boost");
1433         if (IS_ERR(boost_tasks[cpu])) {
1434                 retval = PTR_ERR(boost_tasks[cpu]);
1435                 VERBOSE_PRINTK_STRING("rcu_torture_boost task create failed");
1436                 n_rcu_torture_boost_ktrerror++;
1437                 boost_tasks[cpu] = NULL;
1438                 mutex_unlock(&boost_mutex);
1439                 return retval;
1440         }
1441         kthread_bind(boost_tasks[cpu], cpu);
1442         wake_up_process(boost_tasks[cpu]);
1443         mutex_unlock(&boost_mutex);
1444         return 0;
1445 }
1446
1447 /*
1448  * Cause the rcutorture test to shutdown the system after the test has
1449  * run for the time specified by the shutdown_secs module parameter.
1450  */
1451 static int
1452 rcu_torture_shutdown(void *arg)
1453 {
1454         long delta;
1455         unsigned long jiffies_snap;
1456
1457         VERBOSE_PRINTK_STRING("rcu_torture_shutdown task started");
1458         jiffies_snap = ACCESS_ONCE(jiffies);
1459         while (ULONG_CMP_LT(jiffies_snap, shutdown_time) &&
1460                !kthread_should_stop()) {
1461                 delta = shutdown_time - jiffies_snap;
1462                 if (verbose)
1463                         printk(KERN_ALERT "%s" TORTURE_FLAG
1464                                "rcu_torture_shutdown task: %lu jiffies remaining\n",
1465                                torture_type, delta);
1466                 schedule_timeout_interruptible(delta);
1467                 jiffies_snap = ACCESS_ONCE(jiffies);
1468         }
1469         if (kthread_should_stop()) {
1470                 VERBOSE_PRINTK_STRING("rcu_torture_shutdown task stopping");
1471                 return 0;
1472         }
1473
1474         /* OK, shut down the system. */
1475
1476         VERBOSE_PRINTK_STRING("rcu_torture_shutdown task shutting down system");
1477         shutdown_task = NULL;   /* Avoid self-kill deadlock. */
1478         rcu_torture_cleanup();  /* Get the success/failure message. */
1479         kernel_power_off();     /* Shut down the system. */
1480         return 0;
1481 }
1482
1483 #ifdef CONFIG_HOTPLUG_CPU
1484
1485 /*
1486  * Execute random CPU-hotplug operations at the interval specified
1487  * by the onoff_interval.
1488  */
1489 static int __cpuinit
1490 rcu_torture_onoff(void *arg)
1491 {
1492         int cpu;
1493         int maxcpu = -1;
1494         DEFINE_RCU_RANDOM(rand);
1495
1496         VERBOSE_PRINTK_STRING("rcu_torture_onoff task started");
1497         for_each_online_cpu(cpu)
1498                 maxcpu = cpu;
1499         WARN_ON(maxcpu < 0);
1500         if (onoff_holdoff > 0) {
1501                 VERBOSE_PRINTK_STRING("rcu_torture_onoff begin holdoff");
1502                 schedule_timeout_interruptible(onoff_holdoff * HZ);
1503                 VERBOSE_PRINTK_STRING("rcu_torture_onoff end holdoff");
1504         }
1505         while (!kthread_should_stop()) {
1506                 cpu = (rcu_random(&rand) >> 4) % (maxcpu + 1);
1507                 if (cpu_online(cpu) && cpu_is_hotpluggable(cpu)) {
1508                         if (verbose)
1509                                 printk(KERN_ALERT "%s" TORTURE_FLAG
1510                                        "rcu_torture_onoff task: offlining %d\n",
1511                                        torture_type, cpu);
1512                         n_offline_attempts++;
1513                         if (cpu_down(cpu) == 0) {
1514                                 if (verbose)
1515                                         printk(KERN_ALERT "%s" TORTURE_FLAG
1516                                                "rcu_torture_onoff task: offlined %d\n",
1517                                                torture_type, cpu);
1518                                 n_offline_successes++;
1519                         }
1520                 } else if (cpu_is_hotpluggable(cpu)) {
1521                         if (verbose)
1522                                 printk(KERN_ALERT "%s" TORTURE_FLAG
1523                                        "rcu_torture_onoff task: onlining %d\n",
1524                                        torture_type, cpu);
1525                         n_online_attempts++;
1526                         if (cpu_up(cpu) == 0) {
1527                                 if (verbose)
1528                                         printk(KERN_ALERT "%s" TORTURE_FLAG
1529                                                "rcu_torture_onoff task: onlined %d\n",
1530                                                torture_type, cpu);
1531                                 n_online_successes++;
1532                         }
1533                 }
1534                 schedule_timeout_interruptible(onoff_interval * HZ);
1535         }
1536         VERBOSE_PRINTK_STRING("rcu_torture_onoff task stopping");
1537         return 0;
1538 }
1539
1540 static int __cpuinit
1541 rcu_torture_onoff_init(void)
1542 {
1543         int ret;
1544
1545         if (onoff_interval <= 0)
1546                 return 0;
1547         onoff_task = kthread_run(rcu_torture_onoff, NULL, "rcu_torture_onoff");
1548         if (IS_ERR(onoff_task)) {
1549                 ret = PTR_ERR(onoff_task);
1550                 onoff_task = NULL;
1551                 return ret;
1552         }
1553         return 0;
1554 }
1555
1556 static void rcu_torture_onoff_cleanup(void)
1557 {
1558         if (onoff_task == NULL)
1559                 return;
1560         VERBOSE_PRINTK_STRING("Stopping rcu_torture_onoff task");
1561         kthread_stop(onoff_task);
1562         onoff_task = NULL;
1563 }
1564
1565 #else /* #ifdef CONFIG_HOTPLUG_CPU */
1566
1567 static int
1568 rcu_torture_onoff_init(void)
1569 {
1570         return 0;
1571 }
1572
1573 static void rcu_torture_onoff_cleanup(void)
1574 {
1575 }
1576
1577 #endif /* #else #ifdef CONFIG_HOTPLUG_CPU */
1578
1579 /*
1580  * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
1581  * induces a CPU stall for the time specified by stall_cpu.
1582  */
1583 static int __cpuinit rcu_torture_stall(void *args)
1584 {
1585         unsigned long stop_at;
1586
1587         VERBOSE_PRINTK_STRING("rcu_torture_stall task started");
1588         if (stall_cpu_holdoff > 0) {
1589                 VERBOSE_PRINTK_STRING("rcu_torture_stall begin holdoff");
1590                 schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1591                 VERBOSE_PRINTK_STRING("rcu_torture_stall end holdoff");
1592         }
1593         if (!kthread_should_stop()) {
1594                 stop_at = get_seconds() + stall_cpu;
1595                 /* RCU CPU stall is expected behavior in following code. */
1596                 printk(KERN_ALERT "rcu_torture_stall start.\n");
1597                 rcu_read_lock();
1598                 preempt_disable();
1599                 while (ULONG_CMP_LT(get_seconds(), stop_at))
1600                         continue;  /* Induce RCU CPU stall warning. */
1601                 preempt_enable();
1602                 rcu_read_unlock();
1603                 printk(KERN_ALERT "rcu_torture_stall end.\n");
1604         }
1605         rcutorture_shutdown_absorb("rcu_torture_stall");
1606         while (!kthread_should_stop())
1607                 schedule_timeout_interruptible(10 * HZ);
1608         return 0;
1609 }
1610
1611 /* Spawn CPU-stall kthread, if stall_cpu specified. */
1612 static int __init rcu_torture_stall_init(void)
1613 {
1614         int ret;
1615
1616         if (stall_cpu <= 0)
1617                 return 0;
1618         stall_task = kthread_run(rcu_torture_stall, NULL, "rcu_torture_stall");
1619         if (IS_ERR(stall_task)) {
1620                 ret = PTR_ERR(stall_task);
1621                 stall_task = NULL;
1622                 return ret;
1623         }
1624         return 0;
1625 }
1626
1627 /* Clean up after the CPU-stall kthread, if one was spawned. */
1628 static void rcu_torture_stall_cleanup(void)
1629 {
1630         if (stall_task == NULL)
1631                 return;
1632         VERBOSE_PRINTK_STRING("Stopping rcu_torture_stall_task.");
1633         kthread_stop(stall_task);
1634         stall_task = NULL;
1635 }
1636
1637 /* Callback function for RCU barrier testing. */
1638 void rcu_torture_barrier_cbf(struct rcu_head *rcu)
1639 {
1640         atomic_inc(&barrier_cbs_invoked);
1641 }
1642
1643 /* kthread function to register callbacks used to test RCU barriers. */
1644 static int rcu_torture_barrier_cbs(void *arg)
1645 {
1646         long myid = (long)arg;
1647         bool lastphase = 0;
1648         struct rcu_head rcu;
1649
1650         init_rcu_head_on_stack(&rcu);
1651         VERBOSE_PRINTK_STRING("rcu_torture_barrier_cbs task started");
1652         set_user_nice(current, 19);
1653         do {
1654                 wait_event(barrier_cbs_wq[myid],
1655                            barrier_phase != lastphase ||
1656                            kthread_should_stop() ||
1657                            fullstop != FULLSTOP_DONTSTOP);
1658                 lastphase = barrier_phase;
1659                 smp_mb(); /* ensure barrier_phase load before ->call(). */
1660                 if (kthread_should_stop() || fullstop != FULLSTOP_DONTSTOP)
1661                         break;
1662                 cur_ops->call(&rcu, rcu_torture_barrier_cbf);
1663                 if (atomic_dec_and_test(&barrier_cbs_count))
1664                         wake_up(&barrier_wq);
1665         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1666         VERBOSE_PRINTK_STRING("rcu_torture_barrier_cbs task stopping");
1667         rcutorture_shutdown_absorb("rcu_torture_barrier_cbs");
1668         while (!kthread_should_stop())
1669                 schedule_timeout_interruptible(1);
1670         cur_ops->cb_barrier();
1671         destroy_rcu_head_on_stack(&rcu);
1672         return 0;
1673 }
1674
1675 /* kthread function to drive and coordinate RCU barrier testing. */
1676 static int rcu_torture_barrier(void *arg)
1677 {
1678         int i;
1679
1680         VERBOSE_PRINTK_STRING("rcu_torture_barrier task starting");
1681         do {
1682                 atomic_set(&barrier_cbs_invoked, 0);
1683                 atomic_set(&barrier_cbs_count, n_barrier_cbs);
1684                 smp_mb(); /* Ensure barrier_phase after prior assignments. */
1685                 barrier_phase = !barrier_phase;
1686                 for (i = 0; i < n_barrier_cbs; i++)
1687                         wake_up(&barrier_cbs_wq[i]);
1688                 wait_event(barrier_wq,
1689                            atomic_read(&barrier_cbs_count) == 0 ||
1690                            kthread_should_stop() ||
1691                            fullstop != FULLSTOP_DONTSTOP);
1692                 if (kthread_should_stop() || fullstop != FULLSTOP_DONTSTOP)
1693                         break;
1694                 n_barrier_attempts++;
1695                 cur_ops->cb_barrier();
1696                 if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
1697                         n_rcu_torture_barrier_error++;
1698                         WARN_ON_ONCE(1);
1699                 }
1700                 n_barrier_successes++;
1701                 schedule_timeout_interruptible(HZ / 10);
1702         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1703         VERBOSE_PRINTK_STRING("rcu_torture_barrier task stopping");
1704         rcutorture_shutdown_absorb("rcu_torture_barrier");
1705         while (!kthread_should_stop())
1706                 schedule_timeout_interruptible(1);
1707         return 0;
1708 }
1709
1710 /* Initialize RCU barrier testing. */
1711 static int rcu_torture_barrier_init(void)
1712 {
1713         int i;
1714         int ret;
1715
1716         if (n_barrier_cbs == 0)
1717                 return 0;
1718         if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
1719                 printk(KERN_ALERT "%s" TORTURE_FLAG
1720                        " Call or barrier ops missing for %s,\n",
1721                        torture_type, cur_ops->name);
1722                 printk(KERN_ALERT "%s" TORTURE_FLAG
1723                        " RCU barrier testing omitted from run.\n",
1724                        torture_type);
1725                 return 0;
1726         }
1727         atomic_set(&barrier_cbs_count, 0);
1728         atomic_set(&barrier_cbs_invoked, 0);
1729         barrier_cbs_tasks =
1730                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_tasks[0]),
1731                         GFP_KERNEL);
1732         barrier_cbs_wq =
1733                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_wq[0]),
1734                         GFP_KERNEL);
1735         if (barrier_cbs_tasks == NULL || barrier_cbs_wq == 0)
1736                 return -ENOMEM;
1737         for (i = 0; i < n_barrier_cbs; i++) {
1738                 init_waitqueue_head(&barrier_cbs_wq[i]);
1739                 barrier_cbs_tasks[i] = kthread_run(rcu_torture_barrier_cbs,
1740                                                    (void *)(long)i,
1741                                                    "rcu_torture_barrier_cbs");
1742                 if (IS_ERR(barrier_cbs_tasks[i])) {
1743                         ret = PTR_ERR(barrier_cbs_tasks[i]);
1744                         VERBOSE_PRINTK_ERRSTRING("Failed to create rcu_torture_barrier_cbs");
1745                         barrier_cbs_tasks[i] = NULL;
1746                         return ret;
1747                 }
1748         }
1749         barrier_task = kthread_run(rcu_torture_barrier, NULL,
1750                                    "rcu_torture_barrier");
1751         if (IS_ERR(barrier_task)) {
1752                 ret = PTR_ERR(barrier_task);
1753                 VERBOSE_PRINTK_ERRSTRING("Failed to create rcu_torture_barrier");
1754                 barrier_task = NULL;
1755         }
1756         return 0;
1757 }
1758
1759 /* Clean up after RCU barrier testing. */
1760 static void rcu_torture_barrier_cleanup(void)
1761 {
1762         int i;
1763
1764         if (barrier_task != NULL) {
1765                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_barrier task");
1766                 kthread_stop(barrier_task);
1767                 barrier_task = NULL;
1768         }
1769         if (barrier_cbs_tasks != NULL) {
1770                 for (i = 0; i < n_barrier_cbs; i++) {
1771                         if (barrier_cbs_tasks[i] != NULL) {
1772                                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_barrier_cbs task");
1773                                 kthread_stop(barrier_cbs_tasks[i]);
1774                                 barrier_cbs_tasks[i] = NULL;
1775                         }
1776                 }
1777                 kfree(barrier_cbs_tasks);
1778                 barrier_cbs_tasks = NULL;
1779         }
1780         if (barrier_cbs_wq != NULL) {
1781                 kfree(barrier_cbs_wq);
1782                 barrier_cbs_wq = NULL;
1783         }
1784 }
1785
1786 static int rcutorture_cpu_notify(struct notifier_block *self,
1787                                  unsigned long action, void *hcpu)
1788 {
1789         long cpu = (long)hcpu;
1790
1791         switch (action) {
1792         case CPU_ONLINE:
1793         case CPU_DOWN_FAILED:
1794                 (void)rcutorture_booster_init(cpu);
1795                 break;
1796         case CPU_DOWN_PREPARE:
1797                 rcutorture_booster_cleanup(cpu);
1798                 break;
1799         default:
1800                 break;
1801         }
1802         return NOTIFY_OK;
1803 }
1804
1805 static struct notifier_block rcutorture_cpu_nb = {
1806         .notifier_call = rcutorture_cpu_notify,
1807 };
1808
1809 static void
1810 rcu_torture_cleanup(void)
1811 {
1812         int i;
1813
1814         mutex_lock(&fullstop_mutex);
1815         rcutorture_record_test_transition();
1816         if (fullstop == FULLSTOP_SHUTDOWN) {
1817                 printk(KERN_WARNING /* but going down anyway, so... */
1818                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
1819                 mutex_unlock(&fullstop_mutex);
1820                 schedule_timeout_uninterruptible(10);
1821                 if (cur_ops->cb_barrier != NULL)
1822                         cur_ops->cb_barrier();
1823                 return;
1824         }
1825         fullstop = FULLSTOP_RMMOD;
1826         mutex_unlock(&fullstop_mutex);
1827         unregister_reboot_notifier(&rcutorture_shutdown_nb);
1828         rcu_torture_barrier_cleanup();
1829         rcu_torture_stall_cleanup();
1830         if (stutter_task) {
1831                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
1832                 kthread_stop(stutter_task);
1833         }
1834         stutter_task = NULL;
1835         if (shuffler_task) {
1836                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
1837                 kthread_stop(shuffler_task);
1838                 free_cpumask_var(shuffle_tmp_mask);
1839         }
1840         shuffler_task = NULL;
1841
1842         if (writer_task) {
1843                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
1844                 kthread_stop(writer_task);
1845         }
1846         writer_task = NULL;
1847
1848         if (reader_tasks) {
1849                 for (i = 0; i < nrealreaders; i++) {
1850                         if (reader_tasks[i]) {
1851                                 VERBOSE_PRINTK_STRING(
1852                                         "Stopping rcu_torture_reader task");
1853                                 kthread_stop(reader_tasks[i]);
1854                         }
1855                         reader_tasks[i] = NULL;
1856                 }
1857                 kfree(reader_tasks);
1858                 reader_tasks = NULL;
1859         }
1860         rcu_torture_current = NULL;
1861
1862         if (fakewriter_tasks) {
1863                 for (i = 0; i < nfakewriters; i++) {
1864                         if (fakewriter_tasks[i]) {
1865                                 VERBOSE_PRINTK_STRING(
1866                                         "Stopping rcu_torture_fakewriter task");
1867                                 kthread_stop(fakewriter_tasks[i]);
1868                         }
1869                         fakewriter_tasks[i] = NULL;
1870                 }
1871                 kfree(fakewriter_tasks);
1872                 fakewriter_tasks = NULL;
1873         }
1874
1875         if (stats_task) {
1876                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
1877                 kthread_stop(stats_task);
1878         }
1879         stats_task = NULL;
1880
1881         if (fqs_task) {
1882                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_fqs task");
1883                 kthread_stop(fqs_task);
1884         }
1885         fqs_task = NULL;
1886         if ((test_boost == 1 && cur_ops->can_boost) ||
1887             test_boost == 2) {
1888                 unregister_cpu_notifier(&rcutorture_cpu_nb);
1889                 for_each_possible_cpu(i)
1890                         rcutorture_booster_cleanup(i);
1891         }
1892         if (shutdown_task != NULL) {
1893                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shutdown task");
1894                 kthread_stop(shutdown_task);
1895         }
1896         shutdown_task = NULL;
1897         rcu_torture_onoff_cleanup();
1898
1899         /* Wait for all RCU callbacks to fire.  */
1900
1901         if (cur_ops->cb_barrier != NULL)
1902                 cur_ops->cb_barrier();
1903
1904         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1905
1906         if (cur_ops->cleanup)
1907                 cur_ops->cleanup();
1908         if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
1909                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1910         else if (n_online_successes != n_online_attempts ||
1911                  n_offline_successes != n_offline_attempts)
1912                 rcu_torture_print_module_parms(cur_ops,
1913                                                "End of test: RCU_HOTPLUG");
1914         else
1915                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1916 }
1917
1918 static int __init
1919 rcu_torture_init(void)
1920 {
1921         int i;
1922         int cpu;
1923         int firsterr = 0;
1924         int retval;
1925         static struct rcu_torture_ops *torture_ops[] =
1926                 { &rcu_ops, &rcu_sync_ops, &rcu_expedited_ops,
1927                   &rcu_bh_ops, &rcu_bh_sync_ops, &rcu_bh_expedited_ops,
1928                   &srcu_ops, &srcu_sync_ops, &srcu_expedited_ops,
1929                   &srcu_raw_ops, &srcu_raw_sync_ops,
1930                   &sched_ops, &sched_sync_ops, &sched_expedited_ops, };
1931
1932         mutex_lock(&fullstop_mutex);
1933
1934         /* Process args and tell the world that the torturer is on the job. */
1935         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1936                 cur_ops = torture_ops[i];
1937                 if (strcmp(torture_type, cur_ops->name) == 0)
1938                         break;
1939         }
1940         if (i == ARRAY_SIZE(torture_ops)) {
1941                 printk(KERN_ALERT "rcu-torture: invalid torture type: \"%s\"\n",
1942                        torture_type);
1943                 printk(KERN_ALERT "rcu-torture types:");
1944                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1945                         printk(KERN_ALERT " %s", torture_ops[i]->name);
1946                 printk(KERN_ALERT "\n");
1947                 mutex_unlock(&fullstop_mutex);
1948                 return -EINVAL;
1949         }
1950         if (cur_ops->fqs == NULL && fqs_duration != 0) {
1951                 printk(KERN_ALERT "rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
1952                 fqs_duration = 0;
1953         }
1954         if (cur_ops->init)
1955                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1956
1957         if (nreaders >= 0)
1958                 nrealreaders = nreaders;
1959         else
1960                 nrealreaders = 2 * num_online_cpus();
1961         rcu_torture_print_module_parms(cur_ops, "Start of test");
1962         fullstop = FULLSTOP_DONTSTOP;
1963
1964         /* Set up the freelist. */
1965
1966         INIT_LIST_HEAD(&rcu_torture_freelist);
1967         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1968                 rcu_tortures[i].rtort_mbtest = 0;
1969                 list_add_tail(&rcu_tortures[i].rtort_free,
1970                               &rcu_torture_freelist);
1971         }
1972
1973         /* Initialize the statistics so that each run gets its own numbers. */
1974
1975         rcu_torture_current = NULL;
1976         rcu_torture_current_version = 0;
1977         atomic_set(&n_rcu_torture_alloc, 0);
1978         atomic_set(&n_rcu_torture_alloc_fail, 0);
1979         atomic_set(&n_rcu_torture_free, 0);
1980         atomic_set(&n_rcu_torture_mberror, 0);
1981         atomic_set(&n_rcu_torture_error, 0);
1982         n_rcu_torture_barrier_error = 0;
1983         n_rcu_torture_boost_ktrerror = 0;
1984         n_rcu_torture_boost_rterror = 0;
1985         n_rcu_torture_boost_failure = 0;
1986         n_rcu_torture_boosts = 0;
1987         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1988                 atomic_set(&rcu_torture_wcount[i], 0);
1989         for_each_possible_cpu(cpu) {
1990                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1991                         per_cpu(rcu_torture_count, cpu)[i] = 0;
1992                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
1993                 }
1994         }
1995
1996         /* Start up the kthreads. */
1997
1998         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
1999         writer_task = kthread_run(rcu_torture_writer, NULL,
2000                                   "rcu_torture_writer");
2001         if (IS_ERR(writer_task)) {
2002                 firsterr = PTR_ERR(writer_task);
2003                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
2004                 writer_task = NULL;
2005                 goto unwind;
2006         }
2007         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
2008                                    GFP_KERNEL);
2009         if (fakewriter_tasks == NULL) {
2010                 VERBOSE_PRINTK_ERRSTRING("out of memory");
2011                 firsterr = -ENOMEM;
2012                 goto unwind;
2013         }
2014         for (i = 0; i < nfakewriters; i++) {
2015                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
2016                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
2017                                                   "rcu_torture_fakewriter");
2018                 if (IS_ERR(fakewriter_tasks[i])) {
2019                         firsterr = PTR_ERR(fakewriter_tasks[i]);
2020                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
2021                         fakewriter_tasks[i] = NULL;
2022                         goto unwind;
2023                 }
2024         }
2025         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
2026                                GFP_KERNEL);
2027         if (reader_tasks == NULL) {
2028                 VERBOSE_PRINTK_ERRSTRING("out of memory");
2029                 firsterr = -ENOMEM;
2030                 goto unwind;
2031         }
2032         for (i = 0; i < nrealreaders; i++) {
2033                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
2034                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
2035                                               "rcu_torture_reader");
2036                 if (IS_ERR(reader_tasks[i])) {
2037                         firsterr = PTR_ERR(reader_tasks[i]);
2038                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
2039                         reader_tasks[i] = NULL;
2040                         goto unwind;
2041                 }
2042         }
2043         if (stat_interval > 0) {
2044                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
2045                 stats_task = kthread_run(rcu_torture_stats, NULL,
2046                                         "rcu_torture_stats");
2047                 if (IS_ERR(stats_task)) {
2048                         firsterr = PTR_ERR(stats_task);
2049                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
2050                         stats_task = NULL;
2051                         goto unwind;
2052                 }
2053         }
2054         if (test_no_idle_hz) {
2055                 rcu_idle_cpu = num_online_cpus() - 1;
2056
2057                 if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
2058                         firsterr = -ENOMEM;
2059                         VERBOSE_PRINTK_ERRSTRING("Failed to alloc mask");
2060                         goto unwind;
2061                 }
2062
2063                 /* Create the shuffler thread */
2064                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
2065                                           "rcu_torture_shuffle");
2066                 if (IS_ERR(shuffler_task)) {
2067                         free_cpumask_var(shuffle_tmp_mask);
2068                         firsterr = PTR_ERR(shuffler_task);
2069                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
2070                         shuffler_task = NULL;
2071                         goto unwind;
2072                 }
2073         }
2074         if (stutter < 0)
2075                 stutter = 0;
2076         if (stutter) {
2077                 /* Create the stutter thread */
2078                 stutter_task = kthread_run(rcu_torture_stutter, NULL,
2079                                           "rcu_torture_stutter");
2080                 if (IS_ERR(stutter_task)) {
2081                         firsterr = PTR_ERR(stutter_task);
2082                         VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
2083                         stutter_task = NULL;
2084                         goto unwind;
2085                 }
2086         }
2087         if (fqs_duration < 0)
2088                 fqs_duration = 0;
2089         if (fqs_duration) {
2090                 /* Create the stutter thread */
2091                 fqs_task = kthread_run(rcu_torture_fqs, NULL,
2092                                        "rcu_torture_fqs");
2093                 if (IS_ERR(fqs_task)) {
2094                         firsterr = PTR_ERR(fqs_task);
2095                         VERBOSE_PRINTK_ERRSTRING("Failed to create fqs");
2096                         fqs_task = NULL;
2097                         goto unwind;
2098                 }
2099         }
2100         if (test_boost_interval < 1)
2101                 test_boost_interval = 1;
2102         if (test_boost_duration < 2)
2103                 test_boost_duration = 2;
2104         if ((test_boost == 1 && cur_ops->can_boost) ||
2105             test_boost == 2) {
2106
2107                 boost_starttime = jiffies + test_boost_interval * HZ;
2108                 register_cpu_notifier(&rcutorture_cpu_nb);
2109                 for_each_possible_cpu(i) {
2110                         if (cpu_is_offline(i))
2111                                 continue;  /* Heuristic: CPU can go offline. */
2112                         retval = rcutorture_booster_init(i);
2113                         if (retval < 0) {
2114                                 firsterr = retval;
2115                                 goto unwind;
2116                         }
2117                 }
2118         }
2119         if (shutdown_secs > 0) {
2120                 shutdown_time = jiffies + shutdown_secs * HZ;
2121                 shutdown_task = kthread_run(rcu_torture_shutdown, NULL,
2122                                             "rcu_torture_shutdown");
2123                 if (IS_ERR(shutdown_task)) {
2124                         firsterr = PTR_ERR(shutdown_task);
2125                         VERBOSE_PRINTK_ERRSTRING("Failed to create shutdown");
2126                         shutdown_task = NULL;
2127                         goto unwind;
2128                 }
2129         }
2130         i = rcu_torture_onoff_init();
2131         if (i != 0) {
2132                 firsterr = i;
2133                 goto unwind;
2134         }
2135         register_reboot_notifier(&rcutorture_shutdown_nb);
2136         i = rcu_torture_stall_init();
2137         if (i != 0) {
2138                 firsterr = i;
2139                 goto unwind;
2140         }
2141         retval = rcu_torture_barrier_init();
2142         if (retval != 0) {
2143                 firsterr = retval;
2144                 goto unwind;
2145         }
2146         rcutorture_record_test_transition();
2147         mutex_unlock(&fullstop_mutex);
2148         return 0;
2149
2150 unwind:
2151         mutex_unlock(&fullstop_mutex);
2152         rcu_torture_cleanup();
2153         return firsterr;
2154 }
2155
2156 module_init(rcu_torture_init);
2157 module_exit(rcu_torture_cleanup);