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 <asm/atomic.h>
  37 #include <linux/bitops.h>
  38 #include <linux/completion.h>
  39 #include <linux/moduleparam.h>
  40 #include <linux/percpu.h>
  41 #include <linux/notifier.h>
  42 #include <linux/reboot.h>
  43 #include <linux/freezer.h>
  44 #include <linux/cpu.h>
  45 #include <linux/delay.h>
  46 #include <linux/stat.h>
  47 #include <linux/srcu.h>
  48 #include <linux/slab.h>
  49 #include <asm/byteorder.h>
  50
  51 MODULE_LICENSE("GPL");
  52 MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and "
  53               "Josh Triplett <josh@freedesktop.org>");
  54
  55 static int nreaders = -1;       /* # reader threads, defaults to 2*ncpus */
  56 static int nfakewriters = 4;    /* # fake writer threads */
  57 static int stat_interval;       /* Interval between stats, in seconds. */
  58                                 /*  Defaults to "only at end of test". */
  59 static int verbose;             /* Print more debug info. */
  60 static int test_no_idle_hz;     /* Test RCU's support for tickless idle CPUs. */
  61 static int shuffle_interval = 3; /* Interval between shuffles (in sec)*/
  62 static int stutter = 5;         /* Start/stop testing interval (in sec) */
  63 static int irqreader = 1;       /* RCU readers from irq (timers). */
  64 static int fqs_duration = 0;    /* Duration of bursts (us), 0 to disable. */
  65 static int fqs_holdoff = 0;     /* Hold time within burst (us). */
  66 static int fqs_stutter = 3;     /* Wait time between bursts (s). */
  67 static int test_boost = 1;      /* Test RCU prio boost: 0=no, 1=maybe, 2=yes. */
  68 static int test_boost_interval = 7; /* Interval between boost tests, seconds. */
  69 static int test_boost_duration = 4; /* Duration of each boost test, seconds. */
  70 static char *torture_type = "rcu"; /* What RCU implementation to torture. */
  71
  72 module_param(nreaders, int, 0444);
  73 MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
  74 module_param(nfakewriters, int, 0444);
  75 MODULE_PARM_DESC(nfakewriters, "Number of RCU fake writer threads");
  76 module_param(stat_interval, int, 0444);
  77 MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
  78 module_param(verbose, bool, 0444);
  79 MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
  80 module_param(test_no_idle_hz, bool, 0444);
  81 MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
  82 module_param(shuffle_interval, int, 0444);
  83 MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
  84 module_param(stutter, int, 0444);
  85 MODULE_PARM_DESC(stutter, "Number of seconds to run/halt test");
  86 module_param(irqreader, int, 0444);
  87 MODULE_PARM_DESC(irqreader, "Allow RCU readers from irq handlers");
  88 module_param(fqs_duration, int, 0444);
  89 MODULE_PARM_DESC(fqs_duration, "Duration of fqs bursts (us)");
  90 module_param(fqs_holdoff, int, 0444);
  91 MODULE_PARM_DESC(fqs_holdoff, "Holdoff time within fqs bursts (us)");
  92 module_param(fqs_stutter, int, 0444);
  93 MODULE_PARM_DESC(fqs_stutter, "Wait time between fqs bursts (s)");
  94 module_param(test_boost, int, 0444);
  95 MODULE_PARM_DESC(test_boost, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
  96 module_param(test_boost_interval, int, 0444);
  97 MODULE_PARM_DESC(test_boost_interval, "Interval between boost tests, seconds.");
  98 module_param(test_boost_duration, int, 0444);
  99 MODULE_PARM_DESC(test_boost_duration, "Duration of each boost test, seconds.");
 100 module_param(torture_type, charp, 0444);
 101 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, srcu)");
 102
 103 #define TORTURE_FLAG "-torture:"
 104 #define PRINTK_STRING(s) \
 105         do { printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
 106 #define VERBOSE_PRINTK_STRING(s) \
 107         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
 108 #define VERBOSE_PRINTK_ERRSTRING(s) \
 109         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
 110
 111 static char printk_buf[4096];
 112
 113 static int nrealreaders;
 114 static struct task_struct *writer_task;
 115 static struct task_struct **fakewriter_tasks;
 116 static struct task_struct **reader_tasks;
 117 static struct task_struct *stats_task;
 118 static struct task_struct *shuffler_task;
 119 static struct task_struct *stutter_task;
 120 static struct task_struct *fqs_task;
 121 static struct task_struct *boost_tasks[NR_CPUS];
 122
 123 #define RCU_TORTURE_PIPE_LEN 10
 124
 125 struct rcu_torture {
 126         struct rcu_head rtort_rcu;
 127         int rtort_pipe_count;
 128         struct list_head rtort_free;
 129         int rtort_mbtest;
 130 };
 131
 132 static LIST_HEAD(rcu_torture_freelist);
 133 static struct rcu_torture __rcu *rcu_torture_current;
 134 static unsigned long rcu_torture_current_version;
 135 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 136 static DEFINE_SPINLOCK(rcu_torture_lock);
 137 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
 138         { 0 };
 139 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) =
 140         { 0 };
 141 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 142 static atomic_t n_rcu_torture_alloc;
 143 static atomic_t n_rcu_torture_alloc_fail;
 144 static atomic_t n_rcu_torture_free;
 145 static atomic_t n_rcu_torture_mberror;
 146 static atomic_t n_rcu_torture_error;
 147 static long n_rcu_torture_boost_ktrerror;
 148 static long n_rcu_torture_boost_rterror;
 149 static long n_rcu_torture_boost_failure;
 150 static long n_rcu_torture_boosts;
 151 static long n_rcu_torture_timers;
 152 static struct list_head rcu_torture_removed;
 153 static cpumask_var_t shuffle_tmp_mask;
 154
 155 static int stutter_pause_test;
 156
 157 #if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
 158 #define RCUTORTURE_RUNNABLE_INIT 1
 159 #else
 160 #define RCUTORTURE_RUNNABLE_INIT 0
 161 #endif
 162 int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT;
 163
 164 #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
 165 #define rcu_can_boost() 1
 166 #else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 167 #define rcu_can_boost() 0
 168 #endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 169
 170 static unsigned long boost_starttime;   /* jiffies of next boost test start. */
 171 DEFINE_MUTEX(boost_mutex);              /* protect setting boost_starttime */
 172                                         /*  and boost task create/destroy. */
 173
 174 /* Mediate rmmod and system shutdown.  Concurrent rmmod & shutdown illegal! */
 175
 176 #define FULLSTOP_DONTSTOP 0     /* Normal operation. */
 177 #define FULLSTOP_SHUTDOWN 1     /* System shutdown with rcutorture running. */
 178 #define FULLSTOP_RMMOD    2     /* Normal rmmod of rcutorture. */
 179 static int fullstop = FULLSTOP_RMMOD;
 180 /*
 181  * Protect fullstop transitions and spawning of kthreads.
 182  */
 183 static DEFINE_MUTEX(fullstop_mutex);
 184
 185 /*
 186  * Detect and respond to a system shutdown.
 187  */
 188 static int
 189 rcutorture_shutdown_notify(struct notifier_block *unused1,
 190                            unsigned long unused2, void *unused3)
 191 {
 192         mutex_lock(&fullstop_mutex);
 193         if (fullstop == FULLSTOP_DONTSTOP)
 194                 fullstop = FULLSTOP_SHUTDOWN;
 195         else
 196                 printk(KERN_WARNING /* but going down anyway, so... */
 197                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
 198         mutex_unlock(&fullstop_mutex);
 199         return NOTIFY_DONE;
 200 }
 201
 202 /*
 203  * Absorb kthreads into a kernel function that won't return, so that
 204  * they won't ever access module text or data again.
 205  */
 206 static void rcutorture_shutdown_absorb(char *title)
 207 {
 208         if (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
 209                 printk(KERN_NOTICE
 210                        "rcutorture thread %s parking due to system shutdown\n",
 211                        title);
 212                 schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
 213         }
 214 }
 215
 216 /*
 217  * Allocate an element from the rcu_tortures pool.
 218  */
 219 static struct rcu_torture *
 220 rcu_torture_alloc(void)
 221 {
 222         struct list_head *p;
 223
 224         spin_lock_bh(&rcu_torture_lock);
 225         if (list_empty(&rcu_torture_freelist)) {
 226                 atomic_inc(&n_rcu_torture_alloc_fail);
 227                 spin_unlock_bh(&rcu_torture_lock);
 228                 return NULL;
 229         }
 230         atomic_inc(&n_rcu_torture_alloc);
 231         p = rcu_torture_freelist.next;
 232         list_del_init(p);
 233         spin_unlock_bh(&rcu_torture_lock);
 234         return container_of(p, struct rcu_torture, rtort_free);
 235 }
 236
 237 /*
 238  * Free an element to the rcu_tortures pool.
 239  */
 240 static void
 241 rcu_torture_free(struct rcu_torture *p)
 242 {
 243         atomic_inc(&n_rcu_torture_free);
 244         spin_lock_bh(&rcu_torture_lock);
 245         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 246         spin_unlock_bh(&rcu_torture_lock);
 247 }
 248
 249 struct rcu_random_state {
 250         unsigned long rrs_state;
 251         long rrs_count;
 252 };
 253
 254 #define RCU_RANDOM_MULT 39916801  /* prime */
 255 #define RCU_RANDOM_ADD  479001701 /* prime */
 256 #define RCU_RANDOM_REFRESH 10000
 257
 258 #define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
 259
 260 /*
 261  * Crude but fast random-number generator.  Uses a linear congruential
 262  * generator, with occasional help from cpu_clock().
 263  */
 264 static unsigned long
 265 rcu_random(struct rcu_random_state *rrsp)
 266 {
 267         if (--rrsp->rrs_count < 0) {
 268                 rrsp->rrs_state += (unsigned long)local_clock();
 269                 rrsp->rrs_count = RCU_RANDOM_REFRESH;
 270         }
 271         rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
 272         return swahw32(rrsp->rrs_state);
 273 }
 274
 275 static void
 276 rcu_stutter_wait(char *title)
 277 {
 278         while (stutter_pause_test || !rcutorture_runnable) {
 279                 if (rcutorture_runnable)
 280                         schedule_timeout_interruptible(1);
 281                 else
 282                         schedule_timeout_interruptible(round_jiffies_relative(HZ));
 283                 rcutorture_shutdown_absorb(title);
 284         }
 285 }
 286
 287 /*
 288  * Operations vector for selecting different types of tests.
 289  */
 290
 291 struct rcu_torture_ops {
 292         void (*init)(void);
 293         void (*cleanup)(void);
 294         int (*readlock)(void);
 295         void (*read_delay)(struct rcu_random_state *rrsp);
 296         void (*readunlock)(int idx);
 297         int (*completed)(void);
 298         void (*deferred_free)(struct rcu_torture *p);
 299         void (*sync)(void);
 300         void (*cb_barrier)(void);
 301         void (*fqs)(void);
 302         int (*stats)(char *page);
 303         int irq_capable;
 304         int can_boost;
 305         char *name;
 306 };
 307
 308 static struct rcu_torture_ops *cur_ops;
 309
 310 /*
 311  * Definitions for rcu torture testing.
 312  */
 313
 314 static int rcu_torture_read_lock(void) __acquires(RCU)
 315 {
 316         rcu_read_lock();
 317         return 0;
 318 }
 319
 320 static void rcu_read_delay(struct rcu_random_state *rrsp)
 321 {
 322         const unsigned long shortdelay_us = 200;
 323         const unsigned long longdelay_ms = 50;
 324
 325         /* We want a short delay sometimes to make a reader delay the grace
 326          * period, and we want a long delay occasionally to trigger
 327          * force_quiescent_state. */
 328
 329         if (!(rcu_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
 330                 mdelay(longdelay_ms);
 331         if (!(rcu_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
 332                 udelay(shortdelay_us);
 333 #ifdef CONFIG_PREEMPT
 334         if (!preempt_count() && !(rcu_random(rrsp) % (nrealreaders * 20000)))
 335                 preempt_schedule();  /* No QS if preempt_disable() in effect */
 336 #endif
 337 }
 338
 339 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 340 {
 341         rcu_read_unlock();
 342 }
 343
 344 static int rcu_torture_completed(void)
 345 {
 346         return rcu_batches_completed();
 347 }
 348
 349 static void
 350 rcu_torture_cb(struct rcu_head *p)
 351 {
 352         int i;
 353         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 354
 355         if (fullstop != FULLSTOP_DONTSTOP) {
 356                 /* Test is ending, just drop callbacks on the floor. */
 357                 /* The next initialization will pick up the pieces. */
 358                 return;
 359         }
 360         i = rp->rtort_pipe_count;
 361         if (i > RCU_TORTURE_PIPE_LEN)
 362                 i = RCU_TORTURE_PIPE_LEN;
 363         atomic_inc(&rcu_torture_wcount[i]);
 364         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 365                 rp->rtort_mbtest = 0;
 366                 rcu_torture_free(rp);
 367         } else
 368                 cur_ops->deferred_free(rp);
 369 }
 370
 371 static int rcu_no_completed(void)
 372 {
 373         return 0;
 374 }
 375
 376 static void rcu_torture_deferred_free(struct rcu_torture *p)
 377 {
 378         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 379 }
 380
 381 static struct rcu_torture_ops rcu_ops = {
 382         .init           = NULL,
 383         .cleanup        = NULL,
 384         .readlock       = rcu_torture_read_lock,
 385         .read_delay     = rcu_read_delay,
 386         .readunlock     = rcu_torture_read_unlock,
 387         .completed      = rcu_torture_completed,
 388         .deferred_free  = rcu_torture_deferred_free,
 389         .sync           = synchronize_rcu,
 390         .cb_barrier     = rcu_barrier,
 391         .fqs            = rcu_force_quiescent_state,
 392         .stats          = NULL,
 393         .irq_capable    = 1,
 394         .can_boost      = rcu_can_boost(),
 395         .name           = "rcu"
 396 };
 397
 398 static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
 399 {
 400         int i;
 401         struct rcu_torture *rp;
 402         struct rcu_torture *rp1;
 403
 404         cur_ops->sync();
 405         list_add(&p->rtort_free, &rcu_torture_removed);
 406         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 407                 i = rp->rtort_pipe_count;
 408                 if (i > RCU_TORTURE_PIPE_LEN)
 409                         i = RCU_TORTURE_PIPE_LEN;
 410                 atomic_inc(&rcu_torture_wcount[i]);
 411                 if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 412                         rp->rtort_mbtest = 0;
 413                         list_del(&rp->rtort_free);
 414                         rcu_torture_free(rp);
 415                 }
 416         }
 417 }
 418
 419 static void rcu_sync_torture_init(void)
 420 {
 421         INIT_LIST_HEAD(&rcu_torture_removed);
 422 }
 423
 424 static struct rcu_torture_ops rcu_sync_ops = {
 425         .init           = rcu_sync_torture_init,
 426         .cleanup        = NULL,
 427         .readlock       = rcu_torture_read_lock,
 428         .read_delay     = rcu_read_delay,
 429         .readunlock     = rcu_torture_read_unlock,
 430         .completed      = rcu_torture_completed,
 431         .deferred_free  = rcu_sync_torture_deferred_free,
 432         .sync           = synchronize_rcu,
 433         .cb_barrier     = NULL,
 434         .fqs            = rcu_force_quiescent_state,
 435         .stats          = NULL,
 436         .irq_capable    = 1,
 437         .can_boost      = rcu_can_boost(),
 438         .name           = "rcu_sync"
 439 };
 440
 441 static struct rcu_torture_ops rcu_expedited_ops = {
 442         .init           = rcu_sync_torture_init,
 443         .cleanup        = NULL,
 444         .readlock       = rcu_torture_read_lock,
 445         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 446         .readunlock     = rcu_torture_read_unlock,
 447         .completed      = rcu_no_completed,
 448         .deferred_free  = rcu_sync_torture_deferred_free,
 449         .sync           = synchronize_rcu_expedited,
 450         .cb_barrier     = NULL,
 451         .fqs            = rcu_force_quiescent_state,
 452         .stats          = NULL,
 453         .irq_capable    = 1,
 454         .can_boost      = rcu_can_boost(),
 455         .name           = "rcu_expedited"
 456 };
 457
 458 /*
 459  * Definitions for rcu_bh torture testing.
 460  */
 461
 462 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
 463 {
 464         rcu_read_lock_bh();
 465         return 0;
 466 }
 467
 468 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
 469 {
 470         rcu_read_unlock_bh();
 471 }
 472
 473 static int rcu_bh_torture_completed(void)
 474 {
 475         return rcu_batches_completed_bh();
 476 }
 477
 478 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 479 {
 480         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
 481 }
 482
 483 struct rcu_bh_torture_synchronize {
 484         struct rcu_head head;
 485         struct completion completion;
 486 };
 487
 488 static void rcu_bh_torture_wakeme_after_cb(struct rcu_head *head)
 489 {
 490         struct rcu_bh_torture_synchronize *rcu;
 491
 492         rcu = container_of(head, struct rcu_bh_torture_synchronize, head);
 493         complete(&rcu->completion);
 494 }
 495
 496 static void rcu_bh_torture_synchronize(void)
 497 {
 498         struct rcu_bh_torture_synchronize rcu;
 499
 500         init_rcu_head_on_stack(&rcu.head);
 501         init_completion(&rcu.completion);
 502         call_rcu_bh(&rcu.head, rcu_bh_torture_wakeme_after_cb);
 503         wait_for_completion(&rcu.completion);
 504         destroy_rcu_head_on_stack(&rcu.head);
 505 }
 506
 507 static struct rcu_torture_ops rcu_bh_ops = {
 508         .init           = NULL,
 509         .cleanup        = NULL,
 510         .readlock       = rcu_bh_torture_read_lock,
 511         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 512         .readunlock     = rcu_bh_torture_read_unlock,
 513         .completed      = rcu_bh_torture_completed,
 514         .deferred_free  = rcu_bh_torture_deferred_free,
 515         .sync           = rcu_bh_torture_synchronize,
 516         .cb_barrier     = rcu_barrier_bh,
 517         .fqs            = rcu_bh_force_quiescent_state,
 518         .stats          = NULL,
 519         .irq_capable    = 1,
 520         .name           = "rcu_bh"
 521 };
 522
 523 static struct rcu_torture_ops rcu_bh_sync_ops = {
 524         .init           = rcu_sync_torture_init,
 525         .cleanup        = NULL,
 526         .readlock       = rcu_bh_torture_read_lock,
 527         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 528         .readunlock     = rcu_bh_torture_read_unlock,
 529         .completed      = rcu_bh_torture_completed,
 530         .deferred_free  = rcu_sync_torture_deferred_free,
 531         .sync           = rcu_bh_torture_synchronize,
 532         .cb_barrier     = NULL,
 533         .fqs            = rcu_bh_force_quiescent_state,
 534         .stats          = NULL,
 535         .irq_capable    = 1,
 536         .name           = "rcu_bh_sync"
 537 };
 538
 539 /*
 540  * Definitions for srcu torture testing.
 541  */
 542
 543 static struct srcu_struct srcu_ctl;
 544
 545 static void srcu_torture_init(void)
 546 {
 547         init_srcu_struct(&srcu_ctl);
 548         rcu_sync_torture_init();
 549 }
 550
 551 static void srcu_torture_cleanup(void)
 552 {
 553         synchronize_srcu(&srcu_ctl);
 554         cleanup_srcu_struct(&srcu_ctl);
 555 }
 556
 557 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
 558 {
 559         return srcu_read_lock(&srcu_ctl);
 560 }
 561
 562 static void srcu_read_delay(struct rcu_random_state *rrsp)
 563 {
 564         long delay;
 565         const long uspertick = 1000000 / HZ;
 566         const long longdelay = 10;
 567
 568         /* We want there to be long-running readers, but not all the time. */
 569
 570         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
 571         if (!delay)
 572                 schedule_timeout_interruptible(longdelay);
 573         else
 574                 rcu_read_delay(rrsp);
 575 }
 576
 577 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
 578 {
 579         srcu_read_unlock(&srcu_ctl, idx);
 580 }
 581
 582 static int srcu_torture_completed(void)
 583 {
 584         return srcu_batches_completed(&srcu_ctl);
 585 }
 586
 587 static void srcu_torture_synchronize(void)
 588 {
 589         synchronize_srcu(&srcu_ctl);
 590 }
 591
 592 static int srcu_torture_stats(char *page)
 593 {
 594         int cnt = 0;
 595         int cpu;
 596         int idx = srcu_ctl.completed & 0x1;
 597
 598         cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
 599                        torture_type, TORTURE_FLAG, idx);
 600         for_each_possible_cpu(cpu) {
 601                 cnt += sprintf(&page[cnt], " %d(%d,%d)", cpu,
 602                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
 603                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
 604         }
 605         cnt += sprintf(&page[cnt], "\n");
 606         return cnt;
 607 }
 608
 609 static struct rcu_torture_ops srcu_ops = {
 610         .init           = srcu_torture_init,
 611         .cleanup        = srcu_torture_cleanup,
 612         .readlock       = srcu_torture_read_lock,
 613         .read_delay     = srcu_read_delay,
 614         .readunlock     = srcu_torture_read_unlock,
 615         .completed      = srcu_torture_completed,
 616         .deferred_free  = rcu_sync_torture_deferred_free,
 617         .sync           = srcu_torture_synchronize,
 618         .cb_barrier     = NULL,
 619         .stats          = srcu_torture_stats,
 620         .name           = "srcu"
 621 };
 622
 623 static void srcu_torture_synchronize_expedited(void)
 624 {
 625         synchronize_srcu_expedited(&srcu_ctl);
 626 }
 627
 628 static struct rcu_torture_ops srcu_expedited_ops = {
 629         .init           = srcu_torture_init,
 630         .cleanup        = srcu_torture_cleanup,
 631         .readlock       = srcu_torture_read_lock,
 632         .read_delay     = srcu_read_delay,
 633         .readunlock     = srcu_torture_read_unlock,
 634         .completed      = srcu_torture_completed,
 635         .deferred_free  = rcu_sync_torture_deferred_free,
 636         .sync           = srcu_torture_synchronize_expedited,
 637         .cb_barrier     = NULL,
 638         .stats          = srcu_torture_stats,
 639         .name           = "srcu_expedited"
 640 };
 641
 642 /*
 643  * Definitions for sched torture testing.
 644  */
 645
 646 static int sched_torture_read_lock(void)
 647 {
 648         preempt_disable();
 649         return 0;
 650 }
 651
 652 static void sched_torture_read_unlock(int idx)
 653 {
 654         preempt_enable();
 655 }
 656
 657 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
 658 {
 659         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
 660 }
 661
 662 static void sched_torture_synchronize(void)
 663 {
 664         synchronize_sched();
 665 }
 666
 667 static struct rcu_torture_ops sched_ops = {
 668         .init           = rcu_sync_torture_init,
 669         .cleanup        = NULL,
 670         .readlock       = sched_torture_read_lock,
 671         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 672         .readunlock     = sched_torture_read_unlock,
 673         .completed      = rcu_no_completed,
 674         .deferred_free  = rcu_sched_torture_deferred_free,
 675         .sync           = sched_torture_synchronize,
 676         .cb_barrier     = rcu_barrier_sched,
 677         .fqs            = rcu_sched_force_quiescent_state,
 678         .stats          = NULL,
 679         .irq_capable    = 1,
 680         .name           = "sched"
 681 };
 682
 683 static struct rcu_torture_ops sched_sync_ops = {
 684         .init           = rcu_sync_torture_init,
 685         .cleanup        = NULL,
 686         .readlock       = sched_torture_read_lock,
 687         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 688         .readunlock     = sched_torture_read_unlock,
 689         .completed      = rcu_no_completed,
 690         .deferred_free  = rcu_sync_torture_deferred_free,
 691         .sync           = sched_torture_synchronize,
 692         .cb_barrier     = NULL,
 693         .fqs            = rcu_sched_force_quiescent_state,
 694         .stats          = NULL,
 695         .name           = "sched_sync"
 696 };
 697
 698 static struct rcu_torture_ops sched_expedited_ops = {
 699         .init           = rcu_sync_torture_init,
 700         .cleanup        = NULL,
 701         .readlock       = sched_torture_read_lock,
 702         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 703         .readunlock     = sched_torture_read_unlock,
 704         .completed      = rcu_no_completed,
 705         .deferred_free  = rcu_sync_torture_deferred_free,
 706         .sync           = synchronize_sched_expedited,
 707         .cb_barrier     = NULL,
 708         .fqs            = rcu_sched_force_quiescent_state,
 709         .stats          = NULL,
 710         .irq_capable    = 1,
 711         .name           = "sched_expedited"
 712 };
 713
 714 /*
 715  * RCU torture priority-boost testing.  Runs one real-time thread per
 716  * CPU for moderate bursts, repeatedly registering RCU callbacks and
 717  * spinning waiting for them to be invoked.  If a given callback takes
 718  * too long to be invoked, we assume that priority inversion has occurred.
 719  */
 720
 721 struct rcu_boost_inflight {
 722         struct rcu_head rcu;
 723         int inflight;
 724 };
 725
 726 static void rcu_torture_boost_cb(struct rcu_head *head)
 727 {
 728         struct rcu_boost_inflight *rbip =
 729                 container_of(head, struct rcu_boost_inflight, rcu);
 730
 731         smp_mb(); /* Ensure RCU-core accesses precede clearing ->inflight */
 732         rbip->inflight = 0;
 733 }
 734
 735 static int rcu_torture_boost(void *arg)
 736 {
 737         unsigned long call_rcu_time;
 738         unsigned long endtime;
 739         unsigned long oldstarttime;
 740         struct rcu_boost_inflight rbi = { .inflight = 0 };
 741         struct sched_param sp;
 742
 743         VERBOSE_PRINTK_STRING("rcu_torture_boost started");
 744
 745         /* Set real-time priority. */
 746         sp.sched_priority = 1;
 747         if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 748                 VERBOSE_PRINTK_STRING("rcu_torture_boost RT prio failed!");
 749                 n_rcu_torture_boost_rterror++;
 750         }
 751
 752         init_rcu_head_on_stack(&rbi.rcu);
 753         /* Each pass through the following loop does one boost-test cycle. */
 754         do {
 755                 /* Wait for the next test interval. */
 756                 oldstarttime = boost_starttime;
 757                 while (jiffies - oldstarttime > ULONG_MAX / 2) {
 758                         schedule_timeout_uninterruptible(1);
 759                         rcu_stutter_wait("rcu_torture_boost");
 760                         if (kthread_should_stop() ||
 761                             fullstop != FULLSTOP_DONTSTOP)
 762                                 goto checkwait;
 763                 }
 764
 765                 /* Do one boost-test interval. */
 766                 endtime = oldstarttime + test_boost_duration * HZ;
 767                 call_rcu_time = jiffies;
 768                 while (jiffies - endtime > ULONG_MAX / 2) {
 769                         /* If we don't have a callback in flight, post one. */
 770                         if (!rbi.inflight) {
 771                                 smp_mb(); /* RCU core before ->inflight = 1. */
 772                                 rbi.inflight = 1;
 773                                 call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 774                                 if (jiffies - call_rcu_time >
 775                                          test_boost_duration * HZ - HZ / 2) {
 776                                         VERBOSE_PRINTK_STRING("rcu_torture_boost boosting failed");
 777                                         n_rcu_torture_boost_failure++;
 778                                 }
 779                                 call_rcu_time = jiffies;
 780                         }
 781                         cond_resched();
 782                         rcu_stutter_wait("rcu_torture_boost");
 783                         if (kthread_should_stop() ||
 784                             fullstop != FULLSTOP_DONTSTOP)
 785                                 goto checkwait;
 786                 }
 787
 788                 /*
 789                  * Set the start time of the next test interval.
 790                  * Yes, this is vulnerable to long delays, but such
 791                  * delays simply cause a false negative for the next
 792                  * interval.  Besides, we are running at RT priority,
 793                  * so delays should be relatively rare.
 794                  */
 795                 while (oldstarttime == boost_starttime) {
 796                         if (mutex_trylock(&boost_mutex)) {
 797                                 boost_starttime = jiffies +
 798                                                   test_boost_interval * HZ;
 799                                 n_rcu_torture_boosts++;
 800                                 mutex_unlock(&boost_mutex);
 801                                 break;
 802                         }
 803                         schedule_timeout_uninterruptible(1);
 804                 }
 805
 806                 /* Go do the stutter. */
 807 checkwait:      rcu_stutter_wait("rcu_torture_boost");
 808         } while (!kthread_should_stop() && fullstop  == FULLSTOP_DONTSTOP);
 809
 810         /* Clean up and exit. */
 811         VERBOSE_PRINTK_STRING("rcu_torture_boost task stopping");
 812         destroy_rcu_head_on_stack(&rbi.rcu);
 813         rcutorture_shutdown_absorb("rcu_torture_boost");
 814         while (!kthread_should_stop() || rbi.inflight)
 815                 schedule_timeout_uninterruptible(1);
 816         smp_mb(); /* order accesses to ->inflight before stack-frame death. */
 817         return 0;
 818 }
 819
 820 /*
 821  * RCU torture force-quiescent-state kthread.  Repeatedly induces
 822  * bursts of calls to force_quiescent_state(), increasing the probability
 823  * of occurrence of some important types of race conditions.
 824  */
 825 static int
 826 rcu_torture_fqs(void *arg)
 827 {
 828         unsigned long fqs_resume_time;
 829         int fqs_burst_remaining;
 830
 831         VERBOSE_PRINTK_STRING("rcu_torture_fqs task started");
 832         do {
 833                 fqs_resume_time = jiffies + fqs_stutter * HZ;
 834                 while (jiffies - fqs_resume_time > LONG_MAX) {
 835                         schedule_timeout_interruptible(1);
 836                 }
 837                 fqs_burst_remaining = fqs_duration;
 838                 while (fqs_burst_remaining > 0) {
 839                         cur_ops->fqs();
 840                         udelay(fqs_holdoff);
 841                         fqs_burst_remaining -= fqs_holdoff;
 842                 }
 843                 rcu_stutter_wait("rcu_torture_fqs");
 844         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 845         VERBOSE_PRINTK_STRING("rcu_torture_fqs task stopping");
 846         rcutorture_shutdown_absorb("rcu_torture_fqs");
 847         while (!kthread_should_stop())
 848                 schedule_timeout_uninterruptible(1);
 849         return 0;
 850 }
 851
 852 /*
 853  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 854  * for that pointed to by rcu_torture_current, freeing the old structure
 855  * after a series of grace periods (the "pipeline").
 856  */
 857 static int
 858 rcu_torture_writer(void *arg)
 859 {
 860         int i;
 861         long oldbatch = rcu_batches_completed();
 862         struct rcu_torture *rp;
 863         struct rcu_torture *old_rp;
 864         static DEFINE_RCU_RANDOM(rand);
 865
 866         VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
 867         set_user_nice(current, 19);
 868
 869         do {
 870                 schedule_timeout_uninterruptible(1);
 871                 rp = rcu_torture_alloc();
 872                 if (rp == NULL)
 873                         continue;
 874                 rp->rtort_pipe_count = 0;
 875                 udelay(rcu_random(&rand) & 0x3ff);
 876                 old_rp = rcu_dereference_check(rcu_torture_current,
 877                                                current == writer_task);
 878                 rp->rtort_mbtest = 1;
 879                 rcu_assign_pointer(rcu_torture_current, rp);
 880                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
 881                 if (old_rp) {
 882                         i = old_rp->rtort_pipe_count;
 883                         if (i > RCU_TORTURE_PIPE_LEN)
 884                                 i = RCU_TORTURE_PIPE_LEN;
 885                         atomic_inc(&rcu_torture_wcount[i]);
 886                         old_rp->rtort_pipe_count++;
 887                         cur_ops->deferred_free(old_rp);
 888                 }
 889                 rcutorture_record_progress(++rcu_torture_current_version);
 890                 oldbatch = cur_ops->completed();
 891                 rcu_stutter_wait("rcu_torture_writer");
 892         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 893         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
 894         rcutorture_shutdown_absorb("rcu_torture_writer");
 895         while (!kthread_should_stop())
 896                 schedule_timeout_uninterruptible(1);
 897         return 0;
 898 }
 899
 900 /*
 901  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
 902  * delay between calls.
 903  */
 904 static int
 905 rcu_torture_fakewriter(void *arg)
 906 {
 907         DEFINE_RCU_RANDOM(rand);
 908
 909         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
 910         set_user_nice(current, 19);
 911
 912         do {
 913                 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
 914                 udelay(rcu_random(&rand) & 0x3ff);
 915                 cur_ops->sync();
 916                 rcu_stutter_wait("rcu_torture_fakewriter");
 917         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 918
 919         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
 920         rcutorture_shutdown_absorb("rcu_torture_fakewriter");
 921         while (!kthread_should_stop())
 922                 schedule_timeout_uninterruptible(1);
 923         return 0;
 924 }
 925
 926 /*
 927  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
 928  * incrementing the corresponding element of the pipeline array.  The
 929  * counter in the element should never be greater than 1, otherwise, the
 930  * RCU implementation is broken.
 931  */
 932 static void rcu_torture_timer(unsigned long unused)
 933 {
 934         int idx;
 935         int completed;
 936         static DEFINE_RCU_RANDOM(rand);
 937         static DEFINE_SPINLOCK(rand_lock);
 938         struct rcu_torture *p;
 939         int pipe_count;
 940
 941         idx = cur_ops->readlock();
 942         completed = cur_ops->completed();
 943         p = rcu_dereference_check(rcu_torture_current,
 944                                   rcu_read_lock_held() ||
 945                                   rcu_read_lock_bh_held() ||
 946                                   rcu_read_lock_sched_held() ||
 947                                   srcu_read_lock_held(&srcu_ctl));
 948         if (p == NULL) {
 949                 /* Leave because rcu_torture_writer is not yet underway */
 950                 cur_ops->readunlock(idx);
 951                 return;
 952         }
 953         if (p->rtort_mbtest == 0)
 954                 atomic_inc(&n_rcu_torture_mberror);
 955         spin_lock(&rand_lock);
 956         cur_ops->read_delay(&rand);
 957         n_rcu_torture_timers++;
 958         spin_unlock(&rand_lock);
 959         preempt_disable();
 960         pipe_count = p->rtort_pipe_count;
 961         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
 962                 /* Should not happen, but... */
 963                 pipe_count = RCU_TORTURE_PIPE_LEN;
 964         }
 965         __this_cpu_inc(rcu_torture_count[pipe_count]);
 966         completed = cur_ops->completed() - completed;
 967         if (completed > RCU_TORTURE_PIPE_LEN) {
 968                 /* Should not happen, but... */
 969                 completed = RCU_TORTURE_PIPE_LEN;
 970         }
 971         __this_cpu_inc(rcu_torture_batch[completed]);
 972         preempt_enable();
 973         cur_ops->readunlock(idx);
 974 }
 975
 976 /*
 977  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
 978  * incrementing the corresponding element of the pipeline array.  The
 979  * counter in the element should never be greater than 1, otherwise, the
 980  * RCU implementation is broken.
 981  */
 982 static int
 983 rcu_torture_reader(void *arg)
 984 {
 985         int completed;
 986         int idx;
 987         DEFINE_RCU_RANDOM(rand);
 988         struct rcu_torture *p;
 989         int pipe_count;
 990         struct timer_list t;
 991
 992         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
 993         set_user_nice(current, 19);
 994         if (irqreader && cur_ops->irq_capable)
 995                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
 996
 997         do {
 998                 if (irqreader && cur_ops->irq_capable) {
 999                         if (!timer_pending(&t))
1000                                 mod_timer(&t, jiffies + 1);
1001                 }
1002                 idx = cur_ops->readlock();
1003                 completed = cur_ops->completed();
1004                 p = rcu_dereference_check(rcu_torture_current,
1005                                           rcu_read_lock_held() ||
1006                                           rcu_read_lock_bh_held() ||
1007                                           rcu_read_lock_sched_held() ||
1008                                           srcu_read_lock_held(&srcu_ctl));
1009                 if (p == NULL) {
1010                         /* Wait for rcu_torture_writer to get underway */
1011                         cur_ops->readunlock(idx);
1012                         schedule_timeout_interruptible(HZ);
1013                         continue;
1014                 }
1015                 if (p->rtort_mbtest == 0)
1016                         atomic_inc(&n_rcu_torture_mberror);
1017                 cur_ops->read_delay(&rand);
1018                 preempt_disable();
1019                 pipe_count = p->rtort_pipe_count;
1020                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1021                         /* Should not happen, but... */
1022                         pipe_count = RCU_TORTURE_PIPE_LEN;
1023                 }
1024                 __this_cpu_inc(rcu_torture_count[pipe_count]);
1025                 completed = cur_ops->completed() - completed;
1026                 if (completed > RCU_TORTURE_PIPE_LEN) {
1027                         /* Should not happen, but... */
1028                         completed = RCU_TORTURE_PIPE_LEN;
1029                 }
1030                 __this_cpu_inc(rcu_torture_batch[completed]);
1031                 preempt_enable();
1032                 cur_ops->readunlock(idx);
1033                 schedule();
1034                 rcu_stutter_wait("rcu_torture_reader");
1035         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1036         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
1037         rcutorture_shutdown_absorb("rcu_torture_reader");
1038         if (irqreader && cur_ops->irq_capable)
1039                 del_timer_sync(&t);
1040         while (!kthread_should_stop())
1041                 schedule_timeout_uninterruptible(1);
1042         return 0;
1043 }
1044
1045 /*
1046  * Create an RCU-torture statistics message in the specified buffer.
1047  */
1048 static int
1049 rcu_torture_printk(char *page)
1050 {
1051         int cnt = 0;
1052         int cpu;
1053         int i;
1054         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1055         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1056
1057         for_each_possible_cpu(cpu) {
1058                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1059                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1060                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1061                 }
1062         }
1063         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1064                 if (pipesummary[i] != 0)
1065                         break;
1066         }
1067         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
1068         cnt += sprintf(&page[cnt],
1069                        "rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d "
1070                        "rtmbe: %d rtbke: %ld rtbre: %ld "
1071                        "rtbf: %ld rtb: %ld nt: %ld",
1072                        rcu_torture_current,
1073                        rcu_torture_current_version,
1074                        list_empty(&rcu_torture_freelist),
1075                        atomic_read(&n_rcu_torture_alloc),
1076                        atomic_read(&n_rcu_torture_alloc_fail),
1077                        atomic_read(&n_rcu_torture_free),
1078                        atomic_read(&n_rcu_torture_mberror),
1079                        n_rcu_torture_boost_ktrerror,
1080                        n_rcu_torture_boost_rterror,
1081                        n_rcu_torture_boost_failure,
1082                        n_rcu_torture_boosts,
1083                        n_rcu_torture_timers);
1084         if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1085             n_rcu_torture_boost_ktrerror != 0 ||
1086             n_rcu_torture_boost_rterror != 0 ||
1087             n_rcu_torture_boost_failure != 0)
1088                 cnt += sprintf(&page[cnt], " !!!");
1089         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1090         if (i > 1) {
1091                 cnt += sprintf(&page[cnt], "!!! ");
1092                 atomic_inc(&n_rcu_torture_error);
1093                 WARN_ON_ONCE(1);
1094         }
1095         cnt += sprintf(&page[cnt], "Reader Pipe: ");
1096         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1097                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
1098         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1099         cnt += sprintf(&page[cnt], "Reader Batch: ");
1100         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1101                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
1102         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1103         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
1104         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1105                 cnt += sprintf(&page[cnt], " %d",
1106                                atomic_read(&rcu_torture_wcount[i]));
1107         }
1108         cnt += sprintf(&page[cnt], "\n");
1109         if (cur_ops->stats)
1110                 cnt += cur_ops->stats(&page[cnt]);
1111         return cnt;
1112 }
1113
1114 /*
1115  * Print torture statistics.  Caller must ensure that there is only
1116  * one call to this function at a given time!!!  This is normally
1117  * accomplished by relying on the module system to only have one copy
1118  * of the module loaded, and then by giving the rcu_torture_stats
1119  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1120  * thread is not running).
1121  */
1122 static void
1123 rcu_torture_stats_print(void)
1124 {
1125         int cnt;
1126
1127         cnt = rcu_torture_printk(printk_buf);
1128         printk(KERN_ALERT "%s", printk_buf);
1129 }
1130
1131 /*
1132  * Periodically prints torture statistics, if periodic statistics printing
1133  * was specified via the stat_interval module parameter.
1134  *
1135  * No need to worry about fullstop here, since this one doesn't reference
1136  * volatile state or register callbacks.
1137  */
1138 static int
1139 rcu_torture_stats(void *arg)
1140 {
1141         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
1142         do {
1143                 schedule_timeout_interruptible(stat_interval * HZ);
1144                 rcu_torture_stats_print();
1145                 rcutorture_shutdown_absorb("rcu_torture_stats");
1146         } while (!kthread_should_stop());
1147         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
1148         return 0;
1149 }
1150
1151 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
1152
1153 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
1154  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
1155  */
1156 static void rcu_torture_shuffle_tasks(void)
1157 {
1158         int i;
1159
1160         cpumask_setall(shuffle_tmp_mask);
1161         get_online_cpus();
1162
1163         /* No point in shuffling if there is only one online CPU (ex: UP) */
1164         if (num_online_cpus() == 1) {
1165                 put_online_cpus();
1166                 return;
1167         }
1168
1169         if (rcu_idle_cpu != -1)
1170                 cpumask_clear_cpu(rcu_idle_cpu, shuffle_tmp_mask);
1171
1172         set_cpus_allowed_ptr(current, shuffle_tmp_mask);
1173
1174         if (reader_tasks) {
1175                 for (i = 0; i < nrealreaders; i++)
1176                         if (reader_tasks[i])
1177                                 set_cpus_allowed_ptr(reader_tasks[i],
1178                                                      shuffle_tmp_mask);
1179         }
1180
1181         if (fakewriter_tasks) {
1182                 for (i = 0; i < nfakewriters; i++)
1183                         if (fakewriter_tasks[i])
1184                                 set_cpus_allowed_ptr(fakewriter_tasks[i],
1185                                                      shuffle_tmp_mask);
1186         }
1187
1188         if (writer_task)
1189                 set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
1190
1191         if (stats_task)
1192                 set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
1193
1194         if (rcu_idle_cpu == -1)
1195                 rcu_idle_cpu = num_online_cpus() - 1;
1196         else
1197                 rcu_idle_cpu--;
1198
1199         put_online_cpus();
1200 }
1201
1202 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
1203  * system to become idle at a time and cut off its timer ticks. This is meant
1204  * to test the support for such tickless idle CPU in RCU.
1205  */
1206 static int
1207 rcu_torture_shuffle(void *arg)
1208 {
1209         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
1210         do {
1211                 schedule_timeout_interruptible(shuffle_interval * HZ);
1212                 rcu_torture_shuffle_tasks();
1213                 rcutorture_shutdown_absorb("rcu_torture_shuffle");
1214         } while (!kthread_should_stop());
1215         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
1216         return 0;
1217 }
1218
1219 /* Cause the rcutorture test to "stutter", starting and stopping all
1220  * threads periodically.
1221  */
1222 static int
1223 rcu_torture_stutter(void *arg)
1224 {
1225         VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
1226         do {
1227                 schedule_timeout_interruptible(stutter * HZ);
1228                 stutter_pause_test = 1;
1229                 if (!kthread_should_stop())
1230                         schedule_timeout_interruptible(stutter * HZ);
1231                 stutter_pause_test = 0;
1232                 rcutorture_shutdown_absorb("rcu_torture_stutter");
1233         } while (!kthread_should_stop());
1234         VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
1235         return 0;
1236 }
1237
1238 static inline void
1239 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, char *tag)
1240 {
1241         printk(KERN_ALERT "%s" TORTURE_FLAG
1242                 "--- %s: nreaders=%d nfakewriters=%d "
1243                 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1244                 "shuffle_interval=%d stutter=%d irqreader=%d "
1245                 "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1246                 "test_boost=%d/%d test_boost_interval=%d "
1247                 "test_boost_duration=%d\n",
1248                 torture_type, tag, nrealreaders, nfakewriters,
1249                 stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1250                 stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1251                 test_boost, cur_ops->can_boost,
1252                 test_boost_interval, test_boost_duration);
1253 }
1254
1255 static struct notifier_block rcutorture_shutdown_nb = {
1256         .notifier_call = rcutorture_shutdown_notify,
1257 };
1258
1259 static void rcutorture_booster_cleanup(int cpu)
1260 {
1261         struct task_struct *t;
1262
1263         if (boost_tasks[cpu] == NULL)
1264                 return;
1265         mutex_lock(&boost_mutex);
1266         VERBOSE_PRINTK_STRING("Stopping rcu_torture_boost task");
1267         t = boost_tasks[cpu];
1268         boost_tasks[cpu] = NULL;
1269         mutex_unlock(&boost_mutex);
1270
1271         /* This must be outside of the mutex, otherwise deadlock! */
1272         kthread_stop(t);
1273 }
1274
1275 static int rcutorture_booster_init(int cpu)
1276 {
1277         int retval;
1278
1279         if (boost_tasks[cpu] != NULL)
1280                 return 0;  /* Already created, nothing more to do. */
1281
1282         /* Don't allow time recalculation while creating a new task. */
1283         mutex_lock(&boost_mutex);
1284         VERBOSE_PRINTK_STRING("Creating rcu_torture_boost task");
1285         boost_tasks[cpu] = kthread_create(rcu_torture_boost, NULL,
1286                                           "rcu_torture_boost");
1287         if (IS_ERR(boost_tasks[cpu])) {
1288                 retval = PTR_ERR(boost_tasks[cpu]);
1289                 VERBOSE_PRINTK_STRING("rcu_torture_boost task create failed");
1290                 n_rcu_torture_boost_ktrerror++;
1291                 boost_tasks[cpu] = NULL;
1292                 mutex_unlock(&boost_mutex);
1293                 return retval;
1294         }
1295         kthread_bind(boost_tasks[cpu], cpu);
1296         wake_up_process(boost_tasks[cpu]);
1297         mutex_unlock(&boost_mutex);
1298         return 0;
1299 }
1300
1301 static int rcutorture_cpu_notify(struct notifier_block *self,
1302                                  unsigned long action, void *hcpu)
1303 {
1304         long cpu = (long)hcpu;
1305
1306         switch (action) {
1307         case CPU_ONLINE:
1308         case CPU_DOWN_FAILED:
1309                 (void)rcutorture_booster_init(cpu);
1310                 break;
1311         case CPU_DOWN_PREPARE:
1312                 rcutorture_booster_cleanup(cpu);
1313                 break;
1314         default:
1315                 break;
1316         }
1317         return NOTIFY_OK;
1318 }
1319
1320 static struct notifier_block rcutorture_cpu_nb = {
1321         .notifier_call = rcutorture_cpu_notify,
1322 };
1323
1324 static void
1325 rcu_torture_cleanup(void)
1326 {
1327         int i;
1328
1329         mutex_lock(&fullstop_mutex);
1330         rcutorture_record_test_transition();
1331         if (fullstop == FULLSTOP_SHUTDOWN) {
1332                 printk(KERN_WARNING /* but going down anyway, so... */
1333                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
1334                 mutex_unlock(&fullstop_mutex);
1335                 schedule_timeout_uninterruptible(10);
1336                 if (cur_ops->cb_barrier != NULL)
1337                         cur_ops->cb_barrier();
1338                 return;
1339         }
1340         fullstop = FULLSTOP_RMMOD;
1341         mutex_unlock(&fullstop_mutex);
1342         unregister_reboot_notifier(&rcutorture_shutdown_nb);
1343         if (stutter_task) {
1344                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
1345                 kthread_stop(stutter_task);
1346         }
1347         stutter_task = NULL;
1348         if (shuffler_task) {
1349                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
1350                 kthread_stop(shuffler_task);
1351                 free_cpumask_var(shuffle_tmp_mask);
1352         }
1353         shuffler_task = NULL;
1354
1355         if (writer_task) {
1356                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
1357                 kthread_stop(writer_task);
1358         }
1359         writer_task = NULL;
1360
1361         if (reader_tasks) {
1362                 for (i = 0; i < nrealreaders; i++) {
1363                         if (reader_tasks[i]) {
1364                                 VERBOSE_PRINTK_STRING(
1365                                         "Stopping rcu_torture_reader task");
1366                                 kthread_stop(reader_tasks[i]);
1367                         }
1368                         reader_tasks[i] = NULL;
1369                 }
1370                 kfree(reader_tasks);
1371                 reader_tasks = NULL;
1372         }
1373         rcu_torture_current = NULL;
1374
1375         if (fakewriter_tasks) {
1376                 for (i = 0; i < nfakewriters; i++) {
1377                         if (fakewriter_tasks[i]) {
1378                                 VERBOSE_PRINTK_STRING(
1379                                         "Stopping rcu_torture_fakewriter task");
1380                                 kthread_stop(fakewriter_tasks[i]);
1381                         }
1382                         fakewriter_tasks[i] = NULL;
1383                 }
1384                 kfree(fakewriter_tasks);
1385                 fakewriter_tasks = NULL;
1386         }
1387
1388         if (stats_task) {
1389                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
1390                 kthread_stop(stats_task);
1391         }
1392         stats_task = NULL;
1393
1394         if (fqs_task) {
1395                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_fqs task");
1396                 kthread_stop(fqs_task);
1397         }
1398         fqs_task = NULL;
1399         if ((test_boost == 1 && cur_ops->can_boost) ||
1400             test_boost == 2) {
1401                 unregister_cpu_notifier(&rcutorture_cpu_nb);
1402                 for_each_possible_cpu(i)
1403                         rcutorture_booster_cleanup(i);
1404         }
1405
1406         /* Wait for all RCU callbacks to fire.  */
1407
1408         if (cur_ops->cb_barrier != NULL)
1409                 cur_ops->cb_barrier();
1410
1411         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1412
1413         if (cur_ops->cleanup)
1414                 cur_ops->cleanup();
1415         if (atomic_read(&n_rcu_torture_error))
1416                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1417         else
1418                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1419 }
1420
1421 static int __init
1422 rcu_torture_init(void)
1423 {
1424         int i;
1425         int cpu;
1426         int firsterr = 0;
1427         static struct rcu_torture_ops *torture_ops[] =
1428                 { &rcu_ops, &rcu_sync_ops, &rcu_expedited_ops,
1429                   &rcu_bh_ops, &rcu_bh_sync_ops,
1430                   &srcu_ops, &srcu_expedited_ops,
1431                   &sched_ops, &sched_sync_ops, &sched_expedited_ops, };
1432
1433         mutex_lock(&fullstop_mutex);
1434
1435         /* Process args and tell the world that the torturer is on the job. */
1436         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1437                 cur_ops = torture_ops[i];
1438                 if (strcmp(torture_type, cur_ops->name) == 0)
1439                         break;
1440         }
1441         if (i == ARRAY_SIZE(torture_ops)) {
1442                 printk(KERN_ALERT "rcu-torture: invalid torture type: \"%s\"\n",
1443                        torture_type);
1444                 printk(KERN_ALERT "rcu-torture types:");
1445                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1446                         printk(KERN_ALERT " %s", torture_ops[i]->name);
1447                 printk(KERN_ALERT "\n");
1448                 mutex_unlock(&fullstop_mutex);
1449                 return -EINVAL;
1450         }
1451         if (cur_ops->fqs == NULL && fqs_duration != 0) {
1452                 printk(KERN_ALERT "rcu-torture: ->fqs NULL and non-zero "
1453                                   "fqs_duration, fqs disabled.\n");
1454                 fqs_duration = 0;
1455         }
1456         if (cur_ops->init)
1457                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1458
1459         if (nreaders >= 0)
1460                 nrealreaders = nreaders;
1461         else
1462                 nrealreaders = 2 * num_online_cpus();
1463         rcu_torture_print_module_parms(cur_ops, "Start of test");
1464         fullstop = FULLSTOP_DONTSTOP;
1465
1466         /* Set up the freelist. */
1467
1468         INIT_LIST_HEAD(&rcu_torture_freelist);
1469         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1470                 rcu_tortures[i].rtort_mbtest = 0;
1471                 list_add_tail(&rcu_tortures[i].rtort_free,
1472                               &rcu_torture_freelist);
1473         }
1474
1475         /* Initialize the statistics so that each run gets its own numbers. */
1476
1477         rcu_torture_current = NULL;
1478         rcu_torture_current_version = 0;
1479         atomic_set(&n_rcu_torture_alloc, 0);
1480         atomic_set(&n_rcu_torture_alloc_fail, 0);
1481         atomic_set(&n_rcu_torture_free, 0);
1482         atomic_set(&n_rcu_torture_mberror, 0);
1483         atomic_set(&n_rcu_torture_error, 0);
1484         n_rcu_torture_boost_ktrerror = 0;
1485         n_rcu_torture_boost_rterror = 0;
1486         n_rcu_torture_boost_failure = 0;
1487         n_rcu_torture_boosts = 0;
1488         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1489                 atomic_set(&rcu_torture_wcount[i], 0);
1490         for_each_possible_cpu(cpu) {
1491                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1492                         per_cpu(rcu_torture_count, cpu)[i] = 0;
1493                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
1494                 }
1495         }
1496
1497         /* Start up the kthreads. */
1498
1499         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
1500         writer_task = kthread_run(rcu_torture_writer, NULL,
1501                                   "rcu_torture_writer");
1502         if (IS_ERR(writer_task)) {
1503                 firsterr = PTR_ERR(writer_task);
1504                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
1505                 writer_task = NULL;
1506                 goto unwind;
1507         }
1508         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1509                                    GFP_KERNEL);
1510         if (fakewriter_tasks == NULL) {
1511                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1512                 firsterr = -ENOMEM;
1513                 goto unwind;
1514         }
1515         for (i = 0; i < nfakewriters; i++) {
1516                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
1517                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
1518                                                   "rcu_torture_fakewriter");
1519                 if (IS_ERR(fakewriter_tasks[i])) {
1520                         firsterr = PTR_ERR(fakewriter_tasks[i]);
1521                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
1522                         fakewriter_tasks[i] = NULL;
1523                         goto unwind;
1524                 }
1525         }
1526         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1527                                GFP_KERNEL);
1528         if (reader_tasks == NULL) {
1529                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1530                 firsterr = -ENOMEM;
1531                 goto unwind;
1532         }
1533         for (i = 0; i < nrealreaders; i++) {
1534                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
1535                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
1536                                               "rcu_torture_reader");
1537                 if (IS_ERR(reader_tasks[i])) {
1538                         firsterr = PTR_ERR(reader_tasks[i]);
1539                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
1540                         reader_tasks[i] = NULL;
1541                         goto unwind;
1542                 }
1543         }
1544         if (stat_interval > 0) {
1545                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
1546                 stats_task = kthread_run(rcu_torture_stats, NULL,
1547                                         "rcu_torture_stats");
1548                 if (IS_ERR(stats_task)) {
1549                         firsterr = PTR_ERR(stats_task);
1550                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
1551                         stats_task = NULL;
1552                         goto unwind;
1553                 }
1554         }
1555         if (test_no_idle_hz) {
1556                 rcu_idle_cpu = num_online_cpus() - 1;
1557
1558                 if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
1559                         firsterr = -ENOMEM;
1560                         VERBOSE_PRINTK_ERRSTRING("Failed to alloc mask");
1561                         goto unwind;
1562                 }
1563
1564                 /* Create the shuffler thread */
1565                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
1566                                           "rcu_torture_shuffle");
1567                 if (IS_ERR(shuffler_task)) {
1568                         free_cpumask_var(shuffle_tmp_mask);
1569                         firsterr = PTR_ERR(shuffler_task);
1570                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
1571                         shuffler_task = NULL;
1572                         goto unwind;
1573                 }
1574         }
1575         if (stutter < 0)
1576                 stutter = 0;
1577         if (stutter) {
1578                 /* Create the stutter thread */
1579                 stutter_task = kthread_run(rcu_torture_stutter, NULL,
1580                                           "rcu_torture_stutter");
1581                 if (IS_ERR(stutter_task)) {
1582                         firsterr = PTR_ERR(stutter_task);
1583                         VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
1584                         stutter_task = NULL;
1585                         goto unwind;
1586                 }
1587         }
1588         if (fqs_duration < 0)
1589                 fqs_duration = 0;
1590         if (fqs_duration) {
1591                 /* Create the stutter thread */
1592                 fqs_task = kthread_run(rcu_torture_fqs, NULL,
1593                                        "rcu_torture_fqs");
1594                 if (IS_ERR(fqs_task)) {
1595                         firsterr = PTR_ERR(fqs_task);
1596                         VERBOSE_PRINTK_ERRSTRING("Failed to create fqs");
1597                         fqs_task = NULL;
1598                         goto unwind;
1599                 }
1600         }
1601         if (test_boost_interval < 1)
1602                 test_boost_interval = 1;
1603         if (test_boost_duration < 2)
1604                 test_boost_duration = 2;
1605         if ((test_boost == 1 && cur_ops->can_boost) ||
1606             test_boost == 2) {
1607                 int retval;
1608
1609                 boost_starttime = jiffies + test_boost_interval * HZ;
1610                 register_cpu_notifier(&rcutorture_cpu_nb);
1611                 for_each_possible_cpu(i) {
1612                         if (cpu_is_offline(i))
1613                                 continue;  /* Heuristic: CPU can go offline. */
1614                         retval = rcutorture_booster_init(i);
1615                         if (retval < 0) {
1616                                 firsterr = retval;
1617                                 goto unwind;
1618                         }
1619                 }
1620         }
1621         register_reboot_notifier(&rcutorture_shutdown_nb);
1622         rcutorture_record_test_transition();
1623         mutex_unlock(&fullstop_mutex);
1624         return 0;
1625
1626 unwind:
1627         mutex_unlock(&fullstop_mutex);
1628         rcu_torture_cleanup();
1629         return firsterr;
1630 }
1631
1632 module_init(rcu_torture_init);
1633 module_exit(rcu_torture_cleanup);