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/export.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/module.h>
  36 #include <linux/sched.h>
  37 #include <linux/atomic.h>
  38 #include <linux/bitops.h>
  39 #include <linux/completion.h>
  40 #include <linux/moduleparam.h>
  41 #include <linux/percpu.h>
  42 #include <linux/notifier.h>
  43 #include <linux/reboot.h>
  44 #include <linux/freezer.h>
  45 #include <linux/cpu.h>
  46 #include <linux/delay.h>
  47 #include <linux/stat.h>
  48 #include <linux/srcu.h>
  49 #include <linux/slab.h>
  50 #include <asm/byteorder.h>
  51
  52 MODULE_LICENSE("GPL");
  53 MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and "
  54               "Josh Triplett <josh@freedesktop.org>");
  55
  56 static int nreaders = -1;       /* # reader threads, defaults to 2*ncpus */
  57 static int nfakewriters = 4;    /* # fake writer threads */
  58 static int stat_interval;       /* Interval between stats, in seconds. */
  59                                 /*  Defaults to "only at end of test". */
  60 static int verbose;             /* Print more debug info. */
  61 static int test_no_idle_hz;     /* Test RCU's support for tickless idle CPUs. */
  62 static int shuffle_interval = 3; /* Interval between shuffles (in sec)*/
  63 static int stutter = 5;         /* Start/stop testing interval (in sec) */
  64 static int irqreader = 1;       /* RCU readers from irq (timers). */
  65 static int fqs_duration = 0;    /* Duration of bursts (us), 0 to disable. */
  66 static int fqs_holdoff = 0;     /* Hold time within burst (us). */
  67 static int fqs_stutter = 3;     /* Wait time between bursts (s). */
  68 static int test_boost = 1;      /* Test RCU prio boost: 0=no, 1=maybe, 2=yes. */
  69 static int test_boost_interval = 7; /* Interval between boost tests, seconds. */
  70 static int test_boost_duration = 4; /* Duration of each boost test, seconds. */
  71 static char *torture_type = "rcu"; /* What RCU implementation to torture. */
  72
  73 module_param(nreaders, int, 0444);
  74 MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
  75 module_param(nfakewriters, int, 0444);
  76 MODULE_PARM_DESC(nfakewriters, "Number of RCU fake writer threads");
  77 module_param(stat_interval, int, 0644);
  78 MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
  79 module_param(verbose, bool, 0444);
  80 MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
  81 module_param(test_no_idle_hz, bool, 0444);
  82 MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
  83 module_param(shuffle_interval, int, 0444);
  84 MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
  85 module_param(stutter, int, 0444);
  86 MODULE_PARM_DESC(stutter, "Number of seconds to run/halt test");
  87 module_param(irqreader, int, 0444);
  88 MODULE_PARM_DESC(irqreader, "Allow RCU readers from irq handlers");
  89 module_param(fqs_duration, int, 0444);
  90 MODULE_PARM_DESC(fqs_duration, "Duration of fqs bursts (us)");
  91 module_param(fqs_holdoff, int, 0444);
  92 MODULE_PARM_DESC(fqs_holdoff, "Holdoff time within fqs bursts (us)");
  93 module_param(fqs_stutter, int, 0444);
  94 MODULE_PARM_DESC(fqs_stutter, "Wait time between fqs bursts (s)");
  95 module_param(test_boost, int, 0444);
  96 MODULE_PARM_DESC(test_boost, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
  97 module_param(test_boost_interval, int, 0444);
  98 MODULE_PARM_DESC(test_boost_interval, "Interval between boost tests, seconds.");
  99 module_param(test_boost_duration, int, 0444);
 100 MODULE_PARM_DESC(test_boost_duration, "Duration of each boost test, seconds.");
 101 module_param(torture_type, charp, 0444);
 102 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, srcu)");
 103
 104 #define TORTURE_FLAG "-torture:"
 105 #define PRINTK_STRING(s) \
 106         do { printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
 107 #define VERBOSE_PRINTK_STRING(s) \
 108         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
 109 #define VERBOSE_PRINTK_ERRSTRING(s) \
 110         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
 111
 112 static char printk_buf[4096];
 113
 114 static int nrealreaders;
 115 static struct task_struct *writer_task;
 116 static struct task_struct **fakewriter_tasks;
 117 static struct task_struct **reader_tasks;
 118 static struct task_struct *stats_task;
 119 static struct task_struct *shuffler_task;
 120 static struct task_struct *stutter_task;
 121 static struct task_struct *fqs_task;
 122 static struct task_struct *boost_tasks[NR_CPUS];
 123
 124 #define RCU_TORTURE_PIPE_LEN 10
 125
 126 struct rcu_torture {
 127         struct rcu_head rtort_rcu;
 128         int rtort_pipe_count;
 129         struct list_head rtort_free;
 130         int rtort_mbtest;
 131 };
 132
 133 static LIST_HEAD(rcu_torture_freelist);
 134 static struct rcu_torture __rcu *rcu_torture_current;
 135 static unsigned long rcu_torture_current_version;
 136 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 137 static DEFINE_SPINLOCK(rcu_torture_lock);
 138 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
 139         { 0 };
 140 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) =
 141         { 0 };
 142 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 143 static atomic_t n_rcu_torture_alloc;
 144 static atomic_t n_rcu_torture_alloc_fail;
 145 static atomic_t n_rcu_torture_free;
 146 static atomic_t n_rcu_torture_mberror;
 147 static atomic_t n_rcu_torture_error;
 148 static long n_rcu_torture_boost_ktrerror;
 149 static long n_rcu_torture_boost_rterror;
 150 static long n_rcu_torture_boost_failure;
 151 static long n_rcu_torture_boosts;
 152 static long n_rcu_torture_timers;
 153 static struct list_head rcu_torture_removed;
 154 static cpumask_var_t shuffle_tmp_mask;
 155
 156 static int stutter_pause_test;
 157
 158 #if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
 159 #define RCUTORTURE_RUNNABLE_INIT 1
 160 #else
 161 #define RCUTORTURE_RUNNABLE_INIT 0
 162 #endif
 163 int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT;
 164
 165 #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
 166 #define rcu_can_boost() 1
 167 #else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 168 #define rcu_can_boost() 0
 169 #endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 170
 171 static unsigned long boost_starttime;   /* jiffies of next boost test start. */
 172 DEFINE_MUTEX(boost_mutex);              /* protect setting boost_starttime */
 173                                         /*  and boost task create/destroy. */
 174
 175 /* Mediate rmmod and system shutdown.  Concurrent rmmod & shutdown illegal! */
 176
 177 #define FULLSTOP_DONTSTOP 0     /* Normal operation. */
 178 #define FULLSTOP_SHUTDOWN 1     /* System shutdown with rcutorture running. */
 179 #define FULLSTOP_RMMOD    2     /* Normal rmmod of rcutorture. */
 180 static int fullstop = FULLSTOP_RMMOD;
 181 /*
 182  * Protect fullstop transitions and spawning of kthreads.
 183  */
 184 static DEFINE_MUTEX(fullstop_mutex);
 185
 186 /*
 187  * Detect and respond to a system shutdown.
 188  */
 189 static int
 190 rcutorture_shutdown_notify(struct notifier_block *unused1,
 191                            unsigned long unused2, void *unused3)
 192 {
 193         mutex_lock(&fullstop_mutex);
 194         if (fullstop == FULLSTOP_DONTSTOP)
 195                 fullstop = FULLSTOP_SHUTDOWN;
 196         else
 197                 printk(KERN_WARNING /* but going down anyway, so... */
 198                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
 199         mutex_unlock(&fullstop_mutex);
 200         return NOTIFY_DONE;
 201 }
 202
 203 /*
 204  * Absorb kthreads into a kernel function that won't return, so that
 205  * they won't ever access module text or data again.
 206  */
 207 static void rcutorture_shutdown_absorb(char *title)
 208 {
 209         if (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
 210                 printk(KERN_NOTICE
 211                        "rcutorture thread %s parking due to system shutdown\n",
 212                        title);
 213                 schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
 214         }
 215 }
 216
 217 /*
 218  * Allocate an element from the rcu_tortures pool.
 219  */
 220 static struct rcu_torture *
 221 rcu_torture_alloc(void)
 222 {
 223         struct list_head *p;
 224
 225         spin_lock_bh(&rcu_torture_lock);
 226         if (list_empty(&rcu_torture_freelist)) {
 227                 atomic_inc(&n_rcu_torture_alloc_fail);
 228                 spin_unlock_bh(&rcu_torture_lock);
 229                 return NULL;
 230         }
 231         atomic_inc(&n_rcu_torture_alloc);
 232         p = rcu_torture_freelist.next;
 233         list_del_init(p);
 234         spin_unlock_bh(&rcu_torture_lock);
 235         return container_of(p, struct rcu_torture, rtort_free);
 236 }
 237
 238 /*
 239  * Free an element to the rcu_tortures pool.
 240  */
 241 static void
 242 rcu_torture_free(struct rcu_torture *p)
 243 {
 244         atomic_inc(&n_rcu_torture_free);
 245         spin_lock_bh(&rcu_torture_lock);
 246         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 247         spin_unlock_bh(&rcu_torture_lock);
 248 }
 249
 250 struct rcu_random_state {
 251         unsigned long rrs_state;
 252         long rrs_count;
 253 };
 254
 255 #define RCU_RANDOM_MULT 39916801  /* prime */
 256 #define RCU_RANDOM_ADD  479001701 /* prime */
 257 #define RCU_RANDOM_REFRESH 10000
 258
 259 #define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
 260
 261 /*
 262  * Crude but fast random-number generator.  Uses a linear congruential
 263  * generator, with occasional help from cpu_clock().
 264  */
 265 static unsigned long
 266 rcu_random(struct rcu_random_state *rrsp)
 267 {
 268         if (--rrsp->rrs_count < 0) {
 269                 rrsp->rrs_state += (unsigned long)local_clock();
 270                 rrsp->rrs_count = RCU_RANDOM_REFRESH;
 271         }
 272         rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
 273         return swahw32(rrsp->rrs_state);
 274 }
 275
 276 static void
 277 rcu_stutter_wait(char *title)
 278 {
 279         while (stutter_pause_test || !rcutorture_runnable) {
 280                 if (rcutorture_runnable)
 281                         schedule_timeout_interruptible(1);
 282                 else
 283                         schedule_timeout_interruptible(round_jiffies_relative(HZ));
 284                 rcutorture_shutdown_absorb(title);
 285         }
 286 }
 287
 288 /*
 289  * Operations vector for selecting different types of tests.
 290  */
 291
 292 struct rcu_torture_ops {
 293         void (*init)(void);
 294         void (*cleanup)(void);
 295         int (*readlock)(void);
 296         void (*read_delay)(struct rcu_random_state *rrsp);
 297         void (*readunlock)(int idx);
 298         int (*completed)(void);
 299         void (*deferred_free)(struct rcu_torture *p);
 300         void (*sync)(void);
 301         void (*cb_barrier)(void);
 302         void (*fqs)(void);
 303         int (*stats)(char *page);
 304         int irq_capable;
 305         int can_boost;
 306         char *name;
 307 };
 308
 309 static struct rcu_torture_ops *cur_ops;
 310
 311 /*
 312  * Definitions for rcu torture testing.
 313  */
 314
 315 static int rcu_torture_read_lock(void) __acquires(RCU)
 316 {
 317         rcu_read_lock();
 318         return 0;
 319 }
 320
 321 static void rcu_read_delay(struct rcu_random_state *rrsp)
 322 {
 323         const unsigned long shortdelay_us = 200;
 324         const unsigned long longdelay_ms = 50;
 325
 326         /* We want a short delay sometimes to make a reader delay the grace
 327          * period, and we want a long delay occasionally to trigger
 328          * force_quiescent_state. */
 329
 330         if (!(rcu_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
 331                 mdelay(longdelay_ms);
 332         if (!(rcu_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
 333                 udelay(shortdelay_us);
 334 #ifdef CONFIG_PREEMPT
 335         if (!preempt_count() && !(rcu_random(rrsp) % (nrealreaders * 20000)))
 336                 preempt_schedule();  /* No QS if preempt_disable() in effect */
 337 #endif
 338 }
 339
 340 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 341 {
 342         rcu_read_unlock();
 343 }
 344
 345 static int rcu_torture_completed(void)
 346 {
 347         return rcu_batches_completed();
 348 }
 349
 350 static void
 351 rcu_torture_cb(struct rcu_head *p)
 352 {
 353         int i;
 354         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 355
 356         if (fullstop != FULLSTOP_DONTSTOP) {
 357                 /* Test is ending, just drop callbacks on the floor. */
 358                 /* The next initialization will pick up the pieces. */
 359                 return;
 360         }
 361         i = rp->rtort_pipe_count;
 362         if (i > RCU_TORTURE_PIPE_LEN)
 363                 i = RCU_TORTURE_PIPE_LEN;
 364         atomic_inc(&rcu_torture_wcount[i]);
 365         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 366                 rp->rtort_mbtest = 0;
 367                 rcu_torture_free(rp);
 368         } else
 369                 cur_ops->deferred_free(rp);
 370 }
 371
 372 static int rcu_no_completed(void)
 373 {
 374         return 0;
 375 }
 376
 377 static void rcu_torture_deferred_free(struct rcu_torture *p)
 378 {
 379         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 380 }
 381
 382 static struct rcu_torture_ops rcu_ops = {
 383         .init           = NULL,
 384         .cleanup        = NULL,
 385         .readlock       = rcu_torture_read_lock,
 386         .read_delay     = rcu_read_delay,
 387         .readunlock     = rcu_torture_read_unlock,
 388         .completed      = rcu_torture_completed,
 389         .deferred_free  = rcu_torture_deferred_free,
 390         .sync           = synchronize_rcu,
 391         .cb_barrier     = rcu_barrier,
 392         .fqs            = rcu_force_quiescent_state,
 393         .stats          = NULL,
 394         .irq_capable    = 1,
 395         .can_boost      = rcu_can_boost(),
 396         .name           = "rcu"
 397 };
 398
 399 static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
 400 {
 401         int i;
 402         struct rcu_torture *rp;
 403         struct rcu_torture *rp1;
 404
 405         cur_ops->sync();
 406         list_add(&p->rtort_free, &rcu_torture_removed);
 407         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 408                 i = rp->rtort_pipe_count;
 409                 if (i > RCU_TORTURE_PIPE_LEN)
 410                         i = RCU_TORTURE_PIPE_LEN;
 411                 atomic_inc(&rcu_torture_wcount[i]);
 412                 if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 413                         rp->rtort_mbtest = 0;
 414                         list_del(&rp->rtort_free);
 415                         rcu_torture_free(rp);
 416                 }
 417         }
 418 }
 419
 420 static void rcu_sync_torture_init(void)
 421 {
 422         INIT_LIST_HEAD(&rcu_torture_removed);
 423 }
 424
 425 static struct rcu_torture_ops rcu_sync_ops = {
 426         .init           = rcu_sync_torture_init,
 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_sync_torture_deferred_free,
 433         .sync           = synchronize_rcu,
 434         .cb_barrier     = NULL,
 435         .fqs            = rcu_force_quiescent_state,
 436         .stats          = NULL,
 437         .irq_capable    = 1,
 438         .can_boost      = rcu_can_boost(),
 439         .name           = "rcu_sync"
 440 };
 441
 442 static struct rcu_torture_ops rcu_expedited_ops = {
 443         .init           = rcu_sync_torture_init,
 444         .cleanup        = NULL,
 445         .readlock       = rcu_torture_read_lock,
 446         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 447         .readunlock     = rcu_torture_read_unlock,
 448         .completed      = rcu_no_completed,
 449         .deferred_free  = rcu_sync_torture_deferred_free,
 450         .sync           = synchronize_rcu_expedited,
 451         .cb_barrier     = NULL,
 452         .fqs            = rcu_force_quiescent_state,
 453         .stats          = NULL,
 454         .irq_capable    = 1,
 455         .can_boost      = rcu_can_boost(),
 456         .name           = "rcu_expedited"
 457 };
 458
 459 /*
 460  * Definitions for rcu_bh torture testing.
 461  */
 462
 463 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
 464 {
 465         rcu_read_lock_bh();
 466         return 0;
 467 }
 468
 469 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
 470 {
 471         rcu_read_unlock_bh();
 472 }
 473
 474 static int rcu_bh_torture_completed(void)
 475 {
 476         return rcu_batches_completed_bh();
 477 }
 478
 479 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 480 {
 481         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
 482 }
 483
 484 static struct rcu_torture_ops rcu_bh_ops = {
 485         .init           = NULL,
 486         .cleanup        = NULL,
 487         .readlock       = rcu_bh_torture_read_lock,
 488         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 489         .readunlock     = rcu_bh_torture_read_unlock,
 490         .completed      = rcu_bh_torture_completed,
 491         .deferred_free  = rcu_bh_torture_deferred_free,
 492         .sync           = synchronize_rcu_bh,
 493         .cb_barrier     = rcu_barrier_bh,
 494         .fqs            = rcu_bh_force_quiescent_state,
 495         .stats          = NULL,
 496         .irq_capable    = 1,
 497         .name           = "rcu_bh"
 498 };
 499
 500 static struct rcu_torture_ops rcu_bh_sync_ops = {
 501         .init           = rcu_sync_torture_init,
 502         .cleanup        = NULL,
 503         .readlock       = rcu_bh_torture_read_lock,
 504         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 505         .readunlock     = rcu_bh_torture_read_unlock,
 506         .completed      = rcu_bh_torture_completed,
 507         .deferred_free  = rcu_sync_torture_deferred_free,
 508         .sync           = synchronize_rcu_bh,
 509         .cb_barrier     = NULL,
 510         .fqs            = rcu_bh_force_quiescent_state,
 511         .stats          = NULL,
 512         .irq_capable    = 1,
 513         .name           = "rcu_bh_sync"
 514 };
 515
 516 static struct rcu_torture_ops rcu_bh_expedited_ops = {
 517         .init           = rcu_sync_torture_init,
 518         .cleanup        = NULL,
 519         .readlock       = rcu_bh_torture_read_lock,
 520         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 521         .readunlock     = rcu_bh_torture_read_unlock,
 522         .completed      = rcu_bh_torture_completed,
 523         .deferred_free  = rcu_sync_torture_deferred_free,
 524         .sync           = synchronize_rcu_bh_expedited,
 525         .cb_barrier     = NULL,
 526         .fqs            = rcu_bh_force_quiescent_state,
 527         .stats          = NULL,
 528         .irq_capable    = 1,
 529         .name           = "rcu_bh_expedited"
 530 };
 531
 532 /*
 533  * Definitions for srcu torture testing.
 534  */
 535
 536 static struct srcu_struct srcu_ctl;
 537
 538 static void srcu_torture_init(void)
 539 {
 540         init_srcu_struct(&srcu_ctl);
 541         rcu_sync_torture_init();
 542 }
 543
 544 static void srcu_torture_cleanup(void)
 545 {
 546         synchronize_srcu(&srcu_ctl);
 547         cleanup_srcu_struct(&srcu_ctl);
 548 }
 549
 550 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
 551 {
 552         return srcu_read_lock(&srcu_ctl);
 553 }
 554
 555 static void srcu_read_delay(struct rcu_random_state *rrsp)
 556 {
 557         long delay;
 558         const long uspertick = 1000000 / HZ;
 559         const long longdelay = 10;
 560
 561         /* We want there to be long-running readers, but not all the time. */
 562
 563         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
 564         if (!delay)
 565                 schedule_timeout_interruptible(longdelay);
 566         else
 567                 rcu_read_delay(rrsp);
 568 }
 569
 570 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
 571 {
 572         srcu_read_unlock(&srcu_ctl, idx);
 573 }
 574
 575 static int srcu_torture_completed(void)
 576 {
 577         return srcu_batches_completed(&srcu_ctl);
 578 }
 579
 580 static void srcu_torture_synchronize(void)
 581 {
 582         synchronize_srcu(&srcu_ctl);
 583 }
 584
 585 static int srcu_torture_stats(char *page)
 586 {
 587         int cnt = 0;
 588         int cpu;
 589         int idx = srcu_ctl.completed & 0x1;
 590
 591         cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
 592                        torture_type, TORTURE_FLAG, idx);
 593         for_each_possible_cpu(cpu) {
 594                 cnt += sprintf(&page[cnt], " %d(%d,%d)", cpu,
 595                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
 596                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
 597         }
 598         cnt += sprintf(&page[cnt], "\n");
 599         return cnt;
 600 }
 601
 602 static struct rcu_torture_ops srcu_ops = {
 603         .init           = srcu_torture_init,
 604         .cleanup        = srcu_torture_cleanup,
 605         .readlock       = srcu_torture_read_lock,
 606         .read_delay     = srcu_read_delay,
 607         .readunlock     = srcu_torture_read_unlock,
 608         .completed      = srcu_torture_completed,
 609         .deferred_free  = rcu_sync_torture_deferred_free,
 610         .sync           = srcu_torture_synchronize,
 611         .cb_barrier     = NULL,
 612         .stats          = srcu_torture_stats,
 613         .name           = "srcu"
 614 };
 615
 616 static void srcu_torture_synchronize_expedited(void)
 617 {
 618         synchronize_srcu_expedited(&srcu_ctl);
 619 }
 620
 621 static struct rcu_torture_ops srcu_expedited_ops = {
 622         .init           = srcu_torture_init,
 623         .cleanup        = srcu_torture_cleanup,
 624         .readlock       = srcu_torture_read_lock,
 625         .read_delay     = srcu_read_delay,
 626         .readunlock     = srcu_torture_read_unlock,
 627         .completed      = srcu_torture_completed,
 628         .deferred_free  = rcu_sync_torture_deferred_free,
 629         .sync           = srcu_torture_synchronize_expedited,
 630         .cb_barrier     = NULL,
 631         .stats          = srcu_torture_stats,
 632         .name           = "srcu_expedited"
 633 };
 634
 635 /*
 636  * Definitions for sched torture testing.
 637  */
 638
 639 static int sched_torture_read_lock(void)
 640 {
 641         preempt_disable();
 642         return 0;
 643 }
 644
 645 static void sched_torture_read_unlock(int idx)
 646 {
 647         preempt_enable();
 648 }
 649
 650 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
 651 {
 652         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
 653 }
 654
 655 static struct rcu_torture_ops sched_ops = {
 656         .init           = rcu_sync_torture_init,
 657         .cleanup        = NULL,
 658         .readlock       = sched_torture_read_lock,
 659         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 660         .readunlock     = sched_torture_read_unlock,
 661         .completed      = rcu_no_completed,
 662         .deferred_free  = rcu_sched_torture_deferred_free,
 663         .sync           = synchronize_sched,
 664         .cb_barrier     = rcu_barrier_sched,
 665         .fqs            = rcu_sched_force_quiescent_state,
 666         .stats          = NULL,
 667         .irq_capable    = 1,
 668         .name           = "sched"
 669 };
 670
 671 static struct rcu_torture_ops sched_sync_ops = {
 672         .init           = rcu_sync_torture_init,
 673         .cleanup        = NULL,
 674         .readlock       = sched_torture_read_lock,
 675         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 676         .readunlock     = sched_torture_read_unlock,
 677         .completed      = rcu_no_completed,
 678         .deferred_free  = rcu_sync_torture_deferred_free,
 679         .sync           = synchronize_sched,
 680         .cb_barrier     = NULL,
 681         .fqs            = rcu_sched_force_quiescent_state,
 682         .stats          = NULL,
 683         .name           = "sched_sync"
 684 };
 685
 686 static struct rcu_torture_ops sched_expedited_ops = {
 687         .init           = rcu_sync_torture_init,
 688         .cleanup        = NULL,
 689         .readlock       = sched_torture_read_lock,
 690         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 691         .readunlock     = sched_torture_read_unlock,
 692         .completed      = rcu_no_completed,
 693         .deferred_free  = rcu_sync_torture_deferred_free,
 694         .sync           = synchronize_sched_expedited,
 695         .cb_barrier     = NULL,
 696         .fqs            = rcu_sched_force_quiescent_state,
 697         .stats          = NULL,
 698         .irq_capable    = 1,
 699         .name           = "sched_expedited"
 700 };
 701
 702 /*
 703  * RCU torture priority-boost testing.  Runs one real-time thread per
 704  * CPU for moderate bursts, repeatedly registering RCU callbacks and
 705  * spinning waiting for them to be invoked.  If a given callback takes
 706  * too long to be invoked, we assume that priority inversion has occurred.
 707  */
 708
 709 struct rcu_boost_inflight {
 710         struct rcu_head rcu;
 711         int inflight;
 712 };
 713
 714 static void rcu_torture_boost_cb(struct rcu_head *head)
 715 {
 716         struct rcu_boost_inflight *rbip =
 717                 container_of(head, struct rcu_boost_inflight, rcu);
 718
 719         smp_mb(); /* Ensure RCU-core accesses precede clearing ->inflight */
 720         rbip->inflight = 0;
 721 }
 722
 723 static int rcu_torture_boost(void *arg)
 724 {
 725         unsigned long call_rcu_time;
 726         unsigned long endtime;
 727         unsigned long oldstarttime;
 728         struct rcu_boost_inflight rbi = { .inflight = 0 };
 729         struct sched_param sp;
 730
 731         VERBOSE_PRINTK_STRING("rcu_torture_boost started");
 732
 733         /* Set real-time priority. */
 734         sp.sched_priority = 1;
 735         if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 736                 VERBOSE_PRINTK_STRING("rcu_torture_boost RT prio failed!");
 737                 n_rcu_torture_boost_rterror++;
 738         }
 739
 740         init_rcu_head_on_stack(&rbi.rcu);
 741         /* Each pass through the following loop does one boost-test cycle. */
 742         do {
 743                 /* Wait for the next test interval. */
 744                 oldstarttime = boost_starttime;
 745                 while (ULONG_CMP_LT(jiffies, oldstarttime)) {
 746                         schedule_timeout_uninterruptible(1);
 747                         rcu_stutter_wait("rcu_torture_boost");
 748                         if (kthread_should_stop() ||
 749                             fullstop != FULLSTOP_DONTSTOP)
 750                                 goto checkwait;
 751                 }
 752
 753                 /* Do one boost-test interval. */
 754                 endtime = oldstarttime + test_boost_duration * HZ;
 755                 call_rcu_time = jiffies;
 756                 while (ULONG_CMP_LT(jiffies, endtime)) {
 757                         /* If we don't have a callback in flight, post one. */
 758                         if (!rbi.inflight) {
 759                                 smp_mb(); /* RCU core before ->inflight = 1. */
 760                                 rbi.inflight = 1;
 761                                 call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 762                                 if (jiffies - call_rcu_time >
 763                                          test_boost_duration * HZ - HZ / 2) {
 764                                         VERBOSE_PRINTK_STRING("rcu_torture_boost boosting failed");
 765                                         n_rcu_torture_boost_failure++;
 766                                 }
 767                                 call_rcu_time = jiffies;
 768                         }
 769                         cond_resched();
 770                         rcu_stutter_wait("rcu_torture_boost");
 771                         if (kthread_should_stop() ||
 772                             fullstop != FULLSTOP_DONTSTOP)
 773                                 goto checkwait;
 774                 }
 775
 776                 /*
 777                  * Set the start time of the next test interval.
 778                  * Yes, this is vulnerable to long delays, but such
 779                  * delays simply cause a false negative for the next
 780                  * interval.  Besides, we are running at RT priority,
 781                  * so delays should be relatively rare.
 782                  */
 783                 while (oldstarttime == boost_starttime &&
 784                        !kthread_should_stop()) {
 785                         if (mutex_trylock(&boost_mutex)) {
 786                                 boost_starttime = jiffies +
 787                                                   test_boost_interval * HZ;
 788                                 n_rcu_torture_boosts++;
 789                                 mutex_unlock(&boost_mutex);
 790                                 break;
 791                         }
 792                         schedule_timeout_uninterruptible(1);
 793                 }
 794
 795                 /* Go do the stutter. */
 796 checkwait:      rcu_stutter_wait("rcu_torture_boost");
 797         } while (!kthread_should_stop() && fullstop  == FULLSTOP_DONTSTOP);
 798
 799         /* Clean up and exit. */
 800         VERBOSE_PRINTK_STRING("rcu_torture_boost task stopping");
 801         rcutorture_shutdown_absorb("rcu_torture_boost");
 802         while (!kthread_should_stop() || rbi.inflight)
 803                 schedule_timeout_uninterruptible(1);
 804         smp_mb(); /* order accesses to ->inflight before stack-frame death. */
 805         destroy_rcu_head_on_stack(&rbi.rcu);
 806         return 0;
 807 }
 808
 809 /*
 810  * RCU torture force-quiescent-state kthread.  Repeatedly induces
 811  * bursts of calls to force_quiescent_state(), increasing the probability
 812  * of occurrence of some important types of race conditions.
 813  */
 814 static int
 815 rcu_torture_fqs(void *arg)
 816 {
 817         unsigned long fqs_resume_time;
 818         int fqs_burst_remaining;
 819
 820         VERBOSE_PRINTK_STRING("rcu_torture_fqs task started");
 821         do {
 822                 fqs_resume_time = jiffies + fqs_stutter * HZ;
 823                 while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
 824                        !kthread_should_stop()) {
 825                         schedule_timeout_interruptible(1);
 826                 }
 827                 fqs_burst_remaining = fqs_duration;
 828                 while (fqs_burst_remaining > 0 &&
 829                        !kthread_should_stop()) {
 830                         cur_ops->fqs();
 831                         udelay(fqs_holdoff);
 832                         fqs_burst_remaining -= fqs_holdoff;
 833                 }
 834                 rcu_stutter_wait("rcu_torture_fqs");
 835         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 836         VERBOSE_PRINTK_STRING("rcu_torture_fqs task stopping");
 837         rcutorture_shutdown_absorb("rcu_torture_fqs");
 838         while (!kthread_should_stop())
 839                 schedule_timeout_uninterruptible(1);
 840         return 0;
 841 }
 842
 843 /*
 844  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 845  * for that pointed to by rcu_torture_current, freeing the old structure
 846  * after a series of grace periods (the "pipeline").
 847  */
 848 static int
 849 rcu_torture_writer(void *arg)
 850 {
 851         int i;
 852         long oldbatch = rcu_batches_completed();
 853         struct rcu_torture *rp;
 854         struct rcu_torture *old_rp;
 855         static DEFINE_RCU_RANDOM(rand);
 856
 857         VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
 858         set_user_nice(current, 19);
 859
 860         do {
 861                 schedule_timeout_uninterruptible(1);
 862                 rp = rcu_torture_alloc();
 863                 if (rp == NULL)
 864                         continue;
 865                 rp->rtort_pipe_count = 0;
 866                 udelay(rcu_random(&rand) & 0x3ff);
 867                 old_rp = rcu_dereference_check(rcu_torture_current,
 868                                                current == writer_task);
 869                 rp->rtort_mbtest = 1;
 870                 rcu_assign_pointer(rcu_torture_current, rp);
 871                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
 872                 if (old_rp) {
 873                         i = old_rp->rtort_pipe_count;
 874                         if (i > RCU_TORTURE_PIPE_LEN)
 875                                 i = RCU_TORTURE_PIPE_LEN;
 876                         atomic_inc(&rcu_torture_wcount[i]);
 877                         old_rp->rtort_pipe_count++;
 878                         cur_ops->deferred_free(old_rp);
 879                 }
 880                 rcutorture_record_progress(++rcu_torture_current_version);
 881                 oldbatch = cur_ops->completed();
 882                 rcu_stutter_wait("rcu_torture_writer");
 883         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 884         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
 885         rcutorture_shutdown_absorb("rcu_torture_writer");
 886         while (!kthread_should_stop())
 887                 schedule_timeout_uninterruptible(1);
 888         return 0;
 889 }
 890
 891 /*
 892  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
 893  * delay between calls.
 894  */
 895 static int
 896 rcu_torture_fakewriter(void *arg)
 897 {
 898         DEFINE_RCU_RANDOM(rand);
 899
 900         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
 901         set_user_nice(current, 19);
 902
 903         do {
 904                 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
 905                 udelay(rcu_random(&rand) & 0x3ff);
 906                 cur_ops->sync();
 907                 rcu_stutter_wait("rcu_torture_fakewriter");
 908         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 909
 910         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
 911         rcutorture_shutdown_absorb("rcu_torture_fakewriter");
 912         while (!kthread_should_stop())
 913                 schedule_timeout_uninterruptible(1);
 914         return 0;
 915 }
 916
 917 /*
 918  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
 919  * incrementing the corresponding element of the pipeline array.  The
 920  * counter in the element should never be greater than 1, otherwise, the
 921  * RCU implementation is broken.
 922  */
 923 static void rcu_torture_timer(unsigned long unused)
 924 {
 925         int idx;
 926         int completed;
 927         static DEFINE_RCU_RANDOM(rand);
 928         static DEFINE_SPINLOCK(rand_lock);
 929         struct rcu_torture *p;
 930         int pipe_count;
 931
 932         idx = cur_ops->readlock();
 933         completed = cur_ops->completed();
 934         p = rcu_dereference_check(rcu_torture_current,
 935                                   rcu_read_lock_bh_held() ||
 936                                   rcu_read_lock_sched_held() ||
 937                                   srcu_read_lock_held(&srcu_ctl));
 938         if (p == NULL) {
 939                 /* Leave because rcu_torture_writer is not yet underway */
 940                 cur_ops->readunlock(idx);
 941                 return;
 942         }
 943         if (p->rtort_mbtest == 0)
 944                 atomic_inc(&n_rcu_torture_mberror);
 945         spin_lock(&rand_lock);
 946         cur_ops->read_delay(&rand);
 947         n_rcu_torture_timers++;
 948         spin_unlock(&rand_lock);
 949         preempt_disable();
 950         pipe_count = p->rtort_pipe_count;
 951         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
 952                 /* Should not happen, but... */
 953                 pipe_count = RCU_TORTURE_PIPE_LEN;
 954         }
 955         __this_cpu_inc(rcu_torture_count[pipe_count]);
 956         completed = cur_ops->completed() - completed;
 957         if (completed > RCU_TORTURE_PIPE_LEN) {
 958                 /* Should not happen, but... */
 959                 completed = RCU_TORTURE_PIPE_LEN;
 960         }
 961         __this_cpu_inc(rcu_torture_batch[completed]);
 962         preempt_enable();
 963         cur_ops->readunlock(idx);
 964 }
 965
 966 /*
 967  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
 968  * incrementing the corresponding element of the pipeline array.  The
 969  * counter in the element should never be greater than 1, otherwise, the
 970  * RCU implementation is broken.
 971  */
 972 static int
 973 rcu_torture_reader(void *arg)
 974 {
 975         int completed;
 976         int idx;
 977         DEFINE_RCU_RANDOM(rand);
 978         struct rcu_torture *p;
 979         int pipe_count;
 980         struct timer_list t;
 981
 982         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
 983         set_user_nice(current, 19);
 984         if (irqreader && cur_ops->irq_capable)
 985                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
 986
 987         do {
 988                 if (irqreader && cur_ops->irq_capable) {
 989                         if (!timer_pending(&t))
 990                                 mod_timer(&t, jiffies + 1);
 991                 }
 992                 idx = cur_ops->readlock();
 993                 completed = cur_ops->completed();
 994                 p = rcu_dereference_check(rcu_torture_current,
 995                                           rcu_read_lock_bh_held() ||
 996                                           rcu_read_lock_sched_held() ||
 997                                           srcu_read_lock_held(&srcu_ctl));
 998                 if (p == NULL) {
 999                         /* Wait for rcu_torture_writer to get underway */
1000                         cur_ops->readunlock(idx);
1001                         schedule_timeout_interruptible(HZ);
1002                         continue;
1003                 }
1004                 if (p->rtort_mbtest == 0)
1005                         atomic_inc(&n_rcu_torture_mberror);
1006                 cur_ops->read_delay(&rand);
1007                 preempt_disable();
1008                 pipe_count = p->rtort_pipe_count;
1009                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1010                         /* Should not happen, but... */
1011                         pipe_count = RCU_TORTURE_PIPE_LEN;
1012                 }
1013                 __this_cpu_inc(rcu_torture_count[pipe_count]);
1014                 completed = cur_ops->completed() - completed;
1015                 if (completed > RCU_TORTURE_PIPE_LEN) {
1016                         /* Should not happen, but... */
1017                         completed = RCU_TORTURE_PIPE_LEN;
1018                 }
1019                 __this_cpu_inc(rcu_torture_batch[completed]);
1020                 preempt_enable();
1021                 cur_ops->readunlock(idx);
1022                 schedule();
1023                 rcu_stutter_wait("rcu_torture_reader");
1024         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1025         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
1026         rcutorture_shutdown_absorb("rcu_torture_reader");
1027         if (irqreader && cur_ops->irq_capable)
1028                 del_timer_sync(&t);
1029         while (!kthread_should_stop())
1030                 schedule_timeout_uninterruptible(1);
1031         return 0;
1032 }
1033
1034 /*
1035  * Create an RCU-torture statistics message in the specified buffer.
1036  */
1037 static int
1038 rcu_torture_printk(char *page)
1039 {
1040         int cnt = 0;
1041         int cpu;
1042         int i;
1043         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1044         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1045
1046         for_each_possible_cpu(cpu) {
1047                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1048                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1049                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1050                 }
1051         }
1052         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1053                 if (pipesummary[i] != 0)
1054                         break;
1055         }
1056         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
1057         cnt += sprintf(&page[cnt],
1058                        "rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d "
1059                        "rtmbe: %d rtbke: %ld rtbre: %ld "
1060                        "rtbf: %ld rtb: %ld nt: %ld",
1061                        rcu_torture_current,
1062                        rcu_torture_current_version,
1063                        list_empty(&rcu_torture_freelist),
1064                        atomic_read(&n_rcu_torture_alloc),
1065                        atomic_read(&n_rcu_torture_alloc_fail),
1066                        atomic_read(&n_rcu_torture_free),
1067                        atomic_read(&n_rcu_torture_mberror),
1068                        n_rcu_torture_boost_ktrerror,
1069                        n_rcu_torture_boost_rterror,
1070                        n_rcu_torture_boost_failure,
1071                        n_rcu_torture_boosts,
1072                        n_rcu_torture_timers);
1073         if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1074             n_rcu_torture_boost_ktrerror != 0 ||
1075             n_rcu_torture_boost_rterror != 0 ||
1076             n_rcu_torture_boost_failure != 0)
1077                 cnt += sprintf(&page[cnt], " !!!");
1078         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1079         if (i > 1) {
1080                 cnt += sprintf(&page[cnt], "!!! ");
1081                 atomic_inc(&n_rcu_torture_error);
1082                 WARN_ON_ONCE(1);
1083         }
1084         cnt += sprintf(&page[cnt], "Reader Pipe: ");
1085         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1086                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
1087         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1088         cnt += sprintf(&page[cnt], "Reader Batch: ");
1089         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1090                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
1091         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1092         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
1093         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1094                 cnt += sprintf(&page[cnt], " %d",
1095                                atomic_read(&rcu_torture_wcount[i]));
1096         }
1097         cnt += sprintf(&page[cnt], "\n");
1098         if (cur_ops->stats)
1099                 cnt += cur_ops->stats(&page[cnt]);
1100         return cnt;
1101 }
1102
1103 /*
1104  * Print torture statistics.  Caller must ensure that there is only
1105  * one call to this function at a given time!!!  This is normally
1106  * accomplished by relying on the module system to only have one copy
1107  * of the module loaded, and then by giving the rcu_torture_stats
1108  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1109  * thread is not running).
1110  */
1111 static void
1112 rcu_torture_stats_print(void)
1113 {
1114         int cnt;
1115
1116         cnt = rcu_torture_printk(printk_buf);
1117         printk(KERN_ALERT "%s", printk_buf);
1118 }
1119
1120 /*
1121  * Periodically prints torture statistics, if periodic statistics printing
1122  * was specified via the stat_interval module parameter.
1123  *
1124  * No need to worry about fullstop here, since this one doesn't reference
1125  * volatile state or register callbacks.
1126  */
1127 static int
1128 rcu_torture_stats(void *arg)
1129 {
1130         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
1131         do {
1132                 schedule_timeout_interruptible(stat_interval * HZ);
1133                 rcu_torture_stats_print();
1134                 rcutorture_shutdown_absorb("rcu_torture_stats");
1135         } while (!kthread_should_stop());
1136         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
1137         return 0;
1138 }
1139
1140 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
1141
1142 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
1143  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
1144  */
1145 static void rcu_torture_shuffle_tasks(void)
1146 {
1147         int i;
1148
1149         cpumask_setall(shuffle_tmp_mask);
1150         get_online_cpus();
1151
1152         /* No point in shuffling if there is only one online CPU (ex: UP) */
1153         if (num_online_cpus() == 1) {
1154                 put_online_cpus();
1155                 return;
1156         }
1157
1158         if (rcu_idle_cpu != -1)
1159                 cpumask_clear_cpu(rcu_idle_cpu, shuffle_tmp_mask);
1160
1161         set_cpus_allowed_ptr(current, shuffle_tmp_mask);
1162
1163         if (reader_tasks) {
1164                 for (i = 0; i < nrealreaders; i++)
1165                         if (reader_tasks[i])
1166                                 set_cpus_allowed_ptr(reader_tasks[i],
1167                                                      shuffle_tmp_mask);
1168         }
1169
1170         if (fakewriter_tasks) {
1171                 for (i = 0; i < nfakewriters; i++)
1172                         if (fakewriter_tasks[i])
1173                                 set_cpus_allowed_ptr(fakewriter_tasks[i],
1174                                                      shuffle_tmp_mask);
1175         }
1176
1177         if (writer_task)
1178                 set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
1179
1180         if (stats_task)
1181                 set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
1182
1183         if (rcu_idle_cpu == -1)
1184                 rcu_idle_cpu = num_online_cpus() - 1;
1185         else
1186                 rcu_idle_cpu--;
1187
1188         put_online_cpus();
1189 }
1190
1191 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
1192  * system to become idle at a time and cut off its timer ticks. This is meant
1193  * to test the support for such tickless idle CPU in RCU.
1194  */
1195 static int
1196 rcu_torture_shuffle(void *arg)
1197 {
1198         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
1199         do {
1200                 schedule_timeout_interruptible(shuffle_interval * HZ);
1201                 rcu_torture_shuffle_tasks();
1202                 rcutorture_shutdown_absorb("rcu_torture_shuffle");
1203         } while (!kthread_should_stop());
1204         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
1205         return 0;
1206 }
1207
1208 /* Cause the rcutorture test to "stutter", starting and stopping all
1209  * threads periodically.
1210  */
1211 static int
1212 rcu_torture_stutter(void *arg)
1213 {
1214         VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
1215         do {
1216                 schedule_timeout_interruptible(stutter * HZ);
1217                 stutter_pause_test = 1;
1218                 if (!kthread_should_stop())
1219                         schedule_timeout_interruptible(stutter * HZ);
1220                 stutter_pause_test = 0;
1221                 rcutorture_shutdown_absorb("rcu_torture_stutter");
1222         } while (!kthread_should_stop());
1223         VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
1224         return 0;
1225 }
1226
1227 static inline void
1228 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, char *tag)
1229 {
1230         printk(KERN_ALERT "%s" TORTURE_FLAG
1231                 "--- %s: nreaders=%d nfakewriters=%d "
1232                 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1233                 "shuffle_interval=%d stutter=%d irqreader=%d "
1234                 "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1235                 "test_boost=%d/%d test_boost_interval=%d "
1236                 "test_boost_duration=%d\n",
1237                 torture_type, tag, nrealreaders, nfakewriters,
1238                 stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1239                 stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1240                 test_boost, cur_ops->can_boost,
1241                 test_boost_interval, test_boost_duration);
1242 }
1243
1244 static struct notifier_block rcutorture_shutdown_nb = {
1245         .notifier_call = rcutorture_shutdown_notify,
1246 };
1247
1248 static void rcutorture_booster_cleanup(int cpu)
1249 {
1250         struct task_struct *t;
1251
1252         if (boost_tasks[cpu] == NULL)
1253                 return;
1254         mutex_lock(&boost_mutex);
1255         VERBOSE_PRINTK_STRING("Stopping rcu_torture_boost task");
1256         t = boost_tasks[cpu];
1257         boost_tasks[cpu] = NULL;
1258         mutex_unlock(&boost_mutex);
1259
1260         /* This must be outside of the mutex, otherwise deadlock! */
1261         kthread_stop(t);
1262 }
1263
1264 static int rcutorture_booster_init(int cpu)
1265 {
1266         int retval;
1267
1268         if (boost_tasks[cpu] != NULL)
1269                 return 0;  /* Already created, nothing more to do. */
1270
1271         /* Don't allow time recalculation while creating a new task. */
1272         mutex_lock(&boost_mutex);
1273         VERBOSE_PRINTK_STRING("Creating rcu_torture_boost task");
1274         boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1275                                                   cpu_to_node(cpu),
1276                                                   "rcu_torture_boost");
1277         if (IS_ERR(boost_tasks[cpu])) {
1278                 retval = PTR_ERR(boost_tasks[cpu]);
1279                 VERBOSE_PRINTK_STRING("rcu_torture_boost task create failed");
1280                 n_rcu_torture_boost_ktrerror++;
1281                 boost_tasks[cpu] = NULL;
1282                 mutex_unlock(&boost_mutex);
1283                 return retval;
1284         }
1285         kthread_bind(boost_tasks[cpu], cpu);
1286         wake_up_process(boost_tasks[cpu]);
1287         mutex_unlock(&boost_mutex);
1288         return 0;
1289 }
1290
1291 static int rcutorture_cpu_notify(struct notifier_block *self,
1292                                  unsigned long action, void *hcpu)
1293 {
1294         long cpu = (long)hcpu;
1295
1296         switch (action) {
1297         case CPU_ONLINE:
1298         case CPU_DOWN_FAILED:
1299                 (void)rcutorture_booster_init(cpu);
1300                 break;
1301         case CPU_DOWN_PREPARE:
1302                 rcutorture_booster_cleanup(cpu);
1303                 break;
1304         default:
1305                 break;
1306         }
1307         return NOTIFY_OK;
1308 }
1309
1310 static struct notifier_block rcutorture_cpu_nb = {
1311         .notifier_call = rcutorture_cpu_notify,
1312 };
1313
1314 static void
1315 rcu_torture_cleanup(void)
1316 {
1317         int i;
1318
1319         mutex_lock(&fullstop_mutex);
1320         rcutorture_record_test_transition();
1321         if (fullstop == FULLSTOP_SHUTDOWN) {
1322                 printk(KERN_WARNING /* but going down anyway, so... */
1323                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
1324                 mutex_unlock(&fullstop_mutex);
1325                 schedule_timeout_uninterruptible(10);
1326                 if (cur_ops->cb_barrier != NULL)
1327                         cur_ops->cb_barrier();
1328                 return;
1329         }
1330         fullstop = FULLSTOP_RMMOD;
1331         mutex_unlock(&fullstop_mutex);
1332         unregister_reboot_notifier(&rcutorture_shutdown_nb);
1333         if (stutter_task) {
1334                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
1335                 kthread_stop(stutter_task);
1336         }
1337         stutter_task = NULL;
1338         if (shuffler_task) {
1339                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
1340                 kthread_stop(shuffler_task);
1341                 free_cpumask_var(shuffle_tmp_mask);
1342         }
1343         shuffler_task = NULL;
1344
1345         if (writer_task) {
1346                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
1347                 kthread_stop(writer_task);
1348         }
1349         writer_task = NULL;
1350
1351         if (reader_tasks) {
1352                 for (i = 0; i < nrealreaders; i++) {
1353                         if (reader_tasks[i]) {
1354                                 VERBOSE_PRINTK_STRING(
1355                                         "Stopping rcu_torture_reader task");
1356                                 kthread_stop(reader_tasks[i]);
1357                         }
1358                         reader_tasks[i] = NULL;
1359                 }
1360                 kfree(reader_tasks);
1361                 reader_tasks = NULL;
1362         }
1363         rcu_torture_current = NULL;
1364
1365         if (fakewriter_tasks) {
1366                 for (i = 0; i < nfakewriters; i++) {
1367                         if (fakewriter_tasks[i]) {
1368                                 VERBOSE_PRINTK_STRING(
1369                                         "Stopping rcu_torture_fakewriter task");
1370                                 kthread_stop(fakewriter_tasks[i]);
1371                         }
1372                         fakewriter_tasks[i] = NULL;
1373                 }
1374                 kfree(fakewriter_tasks);
1375                 fakewriter_tasks = NULL;
1376         }
1377
1378         if (stats_task) {
1379                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
1380                 kthread_stop(stats_task);
1381         }
1382         stats_task = NULL;
1383
1384         if (fqs_task) {
1385                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_fqs task");
1386                 kthread_stop(fqs_task);
1387         }
1388         fqs_task = NULL;
1389         if ((test_boost == 1 && cur_ops->can_boost) ||
1390             test_boost == 2) {
1391                 unregister_cpu_notifier(&rcutorture_cpu_nb);
1392                 for_each_possible_cpu(i)
1393                         rcutorture_booster_cleanup(i);
1394         }
1395
1396         /* Wait for all RCU callbacks to fire.  */
1397
1398         if (cur_ops->cb_barrier != NULL)
1399                 cur_ops->cb_barrier();
1400
1401         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1402
1403         if (cur_ops->cleanup)
1404                 cur_ops->cleanup();
1405         if (atomic_read(&n_rcu_torture_error))
1406                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1407         else
1408                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1409 }
1410
1411 static int __init
1412 rcu_torture_init(void)
1413 {
1414         int i;
1415         int cpu;
1416         int firsterr = 0;
1417         static struct rcu_torture_ops *torture_ops[] =
1418                 { &rcu_ops, &rcu_sync_ops, &rcu_expedited_ops,
1419                   &rcu_bh_ops, &rcu_bh_sync_ops, &rcu_bh_expedited_ops,
1420                   &srcu_ops, &srcu_expedited_ops,
1421                   &sched_ops, &sched_sync_ops, &sched_expedited_ops, };
1422
1423         mutex_lock(&fullstop_mutex);
1424
1425         /* Process args and tell the world that the torturer is on the job. */
1426         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1427                 cur_ops = torture_ops[i];
1428                 if (strcmp(torture_type, cur_ops->name) == 0)
1429                         break;
1430         }
1431         if (i == ARRAY_SIZE(torture_ops)) {
1432                 printk(KERN_ALERT "rcu-torture: invalid torture type: \"%s\"\n",
1433                        torture_type);
1434                 printk(KERN_ALERT "rcu-torture types:");
1435                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1436                         printk(KERN_ALERT " %s", torture_ops[i]->name);
1437                 printk(KERN_ALERT "\n");
1438                 mutex_unlock(&fullstop_mutex);
1439                 return -EINVAL;
1440         }
1441         if (cur_ops->fqs == NULL && fqs_duration != 0) {
1442                 printk(KERN_ALERT "rcu-torture: ->fqs NULL and non-zero "
1443                                   "fqs_duration, fqs disabled.\n");
1444                 fqs_duration = 0;
1445         }
1446         if (cur_ops->init)
1447                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1448
1449         if (nreaders >= 0)
1450                 nrealreaders = nreaders;
1451         else
1452                 nrealreaders = 2 * num_online_cpus();
1453         rcu_torture_print_module_parms(cur_ops, "Start of test");
1454         fullstop = FULLSTOP_DONTSTOP;
1455
1456         /* Set up the freelist. */
1457
1458         INIT_LIST_HEAD(&rcu_torture_freelist);
1459         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1460                 rcu_tortures[i].rtort_mbtest = 0;
1461                 list_add_tail(&rcu_tortures[i].rtort_free,
1462                               &rcu_torture_freelist);
1463         }
1464
1465         /* Initialize the statistics so that each run gets its own numbers. */
1466
1467         rcu_torture_current = NULL;
1468         rcu_torture_current_version = 0;
1469         atomic_set(&n_rcu_torture_alloc, 0);
1470         atomic_set(&n_rcu_torture_alloc_fail, 0);
1471         atomic_set(&n_rcu_torture_free, 0);
1472         atomic_set(&n_rcu_torture_mberror, 0);
1473         atomic_set(&n_rcu_torture_error, 0);
1474         n_rcu_torture_boost_ktrerror = 0;
1475         n_rcu_torture_boost_rterror = 0;
1476         n_rcu_torture_boost_failure = 0;
1477         n_rcu_torture_boosts = 0;
1478         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1479                 atomic_set(&rcu_torture_wcount[i], 0);
1480         for_each_possible_cpu(cpu) {
1481                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1482                         per_cpu(rcu_torture_count, cpu)[i] = 0;
1483                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
1484                 }
1485         }
1486
1487         /* Start up the kthreads. */
1488
1489         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
1490         writer_task = kthread_run(rcu_torture_writer, NULL,
1491                                   "rcu_torture_writer");
1492         if (IS_ERR(writer_task)) {
1493                 firsterr = PTR_ERR(writer_task);
1494                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
1495                 writer_task = NULL;
1496                 goto unwind;
1497         }
1498         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1499                                    GFP_KERNEL);
1500         if (fakewriter_tasks == NULL) {
1501                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1502                 firsterr = -ENOMEM;
1503                 goto unwind;
1504         }
1505         for (i = 0; i < nfakewriters; i++) {
1506                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
1507                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
1508                                                   "rcu_torture_fakewriter");
1509                 if (IS_ERR(fakewriter_tasks[i])) {
1510                         firsterr = PTR_ERR(fakewriter_tasks[i]);
1511                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
1512                         fakewriter_tasks[i] = NULL;
1513                         goto unwind;
1514                 }
1515         }
1516         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1517                                GFP_KERNEL);
1518         if (reader_tasks == NULL) {
1519                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1520                 firsterr = -ENOMEM;
1521                 goto unwind;
1522         }
1523         for (i = 0; i < nrealreaders; i++) {
1524                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
1525                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
1526                                               "rcu_torture_reader");
1527                 if (IS_ERR(reader_tasks[i])) {
1528                         firsterr = PTR_ERR(reader_tasks[i]);
1529                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
1530                         reader_tasks[i] = NULL;
1531                         goto unwind;
1532                 }
1533         }
1534         if (stat_interval > 0) {
1535                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
1536                 stats_task = kthread_run(rcu_torture_stats, NULL,
1537                                         "rcu_torture_stats");
1538                 if (IS_ERR(stats_task)) {
1539                         firsterr = PTR_ERR(stats_task);
1540                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
1541                         stats_task = NULL;
1542                         goto unwind;
1543                 }
1544         }
1545         if (test_no_idle_hz) {
1546                 rcu_idle_cpu = num_online_cpus() - 1;
1547
1548                 if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
1549                         firsterr = -ENOMEM;
1550                         VERBOSE_PRINTK_ERRSTRING("Failed to alloc mask");
1551                         goto unwind;
1552                 }
1553
1554                 /* Create the shuffler thread */
1555                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
1556                                           "rcu_torture_shuffle");
1557                 if (IS_ERR(shuffler_task)) {
1558                         free_cpumask_var(shuffle_tmp_mask);
1559                         firsterr = PTR_ERR(shuffler_task);
1560                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
1561                         shuffler_task = NULL;
1562                         goto unwind;
1563                 }
1564         }
1565         if (stutter < 0)
1566                 stutter = 0;
1567         if (stutter) {
1568                 /* Create the stutter thread */
1569                 stutter_task = kthread_run(rcu_torture_stutter, NULL,
1570                                           "rcu_torture_stutter");
1571                 if (IS_ERR(stutter_task)) {
1572                         firsterr = PTR_ERR(stutter_task);
1573                         VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
1574                         stutter_task = NULL;
1575                         goto unwind;
1576                 }
1577         }
1578         if (fqs_duration < 0)
1579                 fqs_duration = 0;
1580         if (fqs_duration) {
1581                 /* Create the stutter thread */
1582                 fqs_task = kthread_run(rcu_torture_fqs, NULL,
1583                                        "rcu_torture_fqs");
1584                 if (IS_ERR(fqs_task)) {
1585                         firsterr = PTR_ERR(fqs_task);
1586                         VERBOSE_PRINTK_ERRSTRING("Failed to create fqs");
1587                         fqs_task = NULL;
1588                         goto unwind;
1589                 }
1590         }
1591         if (test_boost_interval < 1)
1592                 test_boost_interval = 1;
1593         if (test_boost_duration < 2)
1594                 test_boost_duration = 2;
1595         if ((test_boost == 1 && cur_ops->can_boost) ||
1596             test_boost == 2) {
1597                 int retval;
1598
1599                 boost_starttime = jiffies + test_boost_interval * HZ;
1600                 register_cpu_notifier(&rcutorture_cpu_nb);
1601                 for_each_possible_cpu(i) {
1602                         if (cpu_is_offline(i))
1603                                 continue;  /* Heuristic: CPU can go offline. */
1604                         retval = rcutorture_booster_init(i);
1605                         if (retval < 0) {
1606                                 firsterr = retval;
1607                                 goto unwind;
1608                         }
1609                 }
1610         }
1611         register_reboot_notifier(&rcutorture_shutdown_nb);
1612         rcutorture_record_test_transition();
1613         mutex_unlock(&fullstop_mutex);
1614         return 0;
1615
1616 unwind:
1617         mutex_unlock(&fullstop_mutex);
1618         rcu_torture_cleanup();
1619         return firsterr;
1620 }
1621
1622 module_init(rcu_torture_init);
1623 module_exit(rcu_torture_cleanup);