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 #include <linux/sched.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, 0444);
  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 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_allocerror;
 151 static long n_rcu_torture_boost_afferror;
 152 static long n_rcu_torture_boost_failure;
 153 static long n_rcu_torture_boosts;
 154 static long n_rcu_torture_timers;
 155 static struct list_head rcu_torture_removed;
 156 static cpumask_var_t shuffle_tmp_mask;
 157
 158 static int stutter_pause_test;
 159
 160 #if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
 161 #define RCUTORTURE_RUNNABLE_INIT 1
 162 #else
 163 #define RCUTORTURE_RUNNABLE_INIT 0
 164 #endif
 165 int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT;
 166
 167 #ifdef CONFIG_RCU_BOOST
 168 #define rcu_can_boost() 1
 169 #else /* #ifdef CONFIG_RCU_BOOST */
 170 #define rcu_can_boost() 0
 171 #endif /* #else #ifdef CONFIG_RCU_BOOST */
 172
 173 static unsigned long boost_starttime;   /* jiffies of next boost test start. */
 174 DEFINE_MUTEX(boost_mutex);              /* protect setting boost_starttime */
 175                                         /*  and boost task create/destroy. */
 176
 177 /* Mediate rmmod and system shutdown.  Concurrent rmmod & shutdown illegal! */
 178
 179 #define FULLSTOP_DONTSTOP 0     /* Normal operation. */
 180 #define FULLSTOP_SHUTDOWN 1     /* System shutdown with rcutorture running. */
 181 #define FULLSTOP_RMMOD    2     /* Normal rmmod of rcutorture. */
 182 static int fullstop = FULLSTOP_RMMOD;
 183 /*
 184  * Protect fullstop transitions and spawning of kthreads.
 185  */
 186 static DEFINE_MUTEX(fullstop_mutex);
 187
 188 /*
 189  * Detect and respond to a system shutdown.
 190  */
 191 static int
 192 rcutorture_shutdown_notify(struct notifier_block *unused1,
 193                            unsigned long unused2, void *unused3)
 194 {
 195         mutex_lock(&fullstop_mutex);
 196         if (fullstop == FULLSTOP_DONTSTOP)
 197                 fullstop = FULLSTOP_SHUTDOWN;
 198         else
 199                 printk(KERN_WARNING /* but going down anyway, so... */
 200                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
 201         mutex_unlock(&fullstop_mutex);
 202         return NOTIFY_DONE;
 203 }
 204
 205 /*
 206  * Absorb kthreads into a kernel function that won't return, so that
 207  * they won't ever access module text or data again.
 208  */
 209 static void rcutorture_shutdown_absorb(char *title)
 210 {
 211         if (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
 212                 printk(KERN_NOTICE
 213                        "rcutorture thread %s parking due to system shutdown\n",
 214                        title);
 215                 schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
 216         }
 217 }
 218
 219 /*
 220  * Allocate an element from the rcu_tortures pool.
 221  */
 222 static struct rcu_torture *
 223 rcu_torture_alloc(void)
 224 {
 225         struct list_head *p;
 226
 227         spin_lock_bh(&rcu_torture_lock);
 228         if (list_empty(&rcu_torture_freelist)) {
 229                 atomic_inc(&n_rcu_torture_alloc_fail);
 230                 spin_unlock_bh(&rcu_torture_lock);
 231                 return NULL;
 232         }
 233         atomic_inc(&n_rcu_torture_alloc);
 234         p = rcu_torture_freelist.next;
 235         list_del_init(p);
 236         spin_unlock_bh(&rcu_torture_lock);
 237         return container_of(p, struct rcu_torture, rtort_free);
 238 }
 239
 240 /*
 241  * Free an element to the rcu_tortures pool.
 242  */
 243 static void
 244 rcu_torture_free(struct rcu_torture *p)
 245 {
 246         atomic_inc(&n_rcu_torture_free);
 247         spin_lock_bh(&rcu_torture_lock);
 248         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 249         spin_unlock_bh(&rcu_torture_lock);
 250 }
 251
 252 struct rcu_random_state {
 253         unsigned long rrs_state;
 254         long rrs_count;
 255 };
 256
 257 #define RCU_RANDOM_MULT 39916801  /* prime */
 258 #define RCU_RANDOM_ADD  479001701 /* prime */
 259 #define RCU_RANDOM_REFRESH 10000
 260
 261 #define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
 262
 263 /*
 264  * Crude but fast random-number generator.  Uses a linear congruential
 265  * generator, with occasional help from cpu_clock().
 266  */
 267 static unsigned long
 268 rcu_random(struct rcu_random_state *rrsp)
 269 {
 270         if (--rrsp->rrs_count < 0) {
 271                 rrsp->rrs_state += (unsigned long)local_clock();
 272                 rrsp->rrs_count = RCU_RANDOM_REFRESH;
 273         }
 274         rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
 275         return swahw32(rrsp->rrs_state);
 276 }
 277
 278 static void
 279 rcu_stutter_wait(char *title)
 280 {
 281         while (stutter_pause_test || !rcutorture_runnable) {
 282                 if (rcutorture_runnable)
 283                         schedule_timeout_interruptible(1);
 284                 else
 285                         schedule_timeout_interruptible(round_jiffies_relative(HZ));
 286                 rcutorture_shutdown_absorb(title);
 287         }
 288 }
 289
 290 /*
 291  * Operations vector for selecting different types of tests.
 292  */
 293
 294 struct rcu_torture_ops {
 295         void (*init)(void);
 296         void (*cleanup)(void);
 297         int (*readlock)(void);
 298         void (*read_delay)(struct rcu_random_state *rrsp);
 299         void (*readunlock)(int idx);
 300         int (*completed)(void);
 301         void (*deferred_free)(struct rcu_torture *p);
 302         void (*sync)(void);
 303         void (*cb_barrier)(void);
 304         void (*fqs)(void);
 305         int (*stats)(char *page);
 306         int irq_capable;
 307         int can_boost;
 308         char *name;
 309 };
 310
 311 static struct rcu_torture_ops *cur_ops;
 312
 313 /*
 314  * Definitions for rcu torture testing.
 315  */
 316
 317 static int rcu_torture_read_lock(void) __acquires(RCU)
 318 {
 319         rcu_read_lock();
 320         return 0;
 321 }
 322
 323 static void rcu_read_delay(struct rcu_random_state *rrsp)
 324 {
 325         const unsigned long shortdelay_us = 200;
 326         const unsigned long longdelay_ms = 50;
 327
 328         /* We want a short delay sometimes to make a reader delay the grace
 329          * period, and we want a long delay occasionally to trigger
 330          * force_quiescent_state. */
 331
 332         if (!(rcu_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
 333                 mdelay(longdelay_ms);
 334         if (!(rcu_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
 335                 udelay(shortdelay_us);
 336 #ifdef CONFIG_PREEMPT
 337         if (!preempt_count() && !(rcu_random(rrsp) % (nrealreaders * 20000)))
 338                 preempt_schedule();  /* No QS if preempt_disable() in effect */
 339 #endif
 340 }
 341
 342 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 343 {
 344         rcu_read_unlock();
 345 }
 346
 347 static int rcu_torture_completed(void)
 348 {
 349         return rcu_batches_completed();
 350 }
 351
 352 static void
 353 rcu_torture_cb(struct rcu_head *p)
 354 {
 355         int i;
 356         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 357
 358         if (fullstop != FULLSTOP_DONTSTOP) {
 359                 /* Test is ending, just drop callbacks on the floor. */
 360                 /* The next initialization will pick up the pieces. */
 361                 return;
 362         }
 363         i = rp->rtort_pipe_count;
 364         if (i > RCU_TORTURE_PIPE_LEN)
 365                 i = RCU_TORTURE_PIPE_LEN;
 366         atomic_inc(&rcu_torture_wcount[i]);
 367         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 368                 rp->rtort_mbtest = 0;
 369                 rcu_torture_free(rp);
 370         } else
 371                 cur_ops->deferred_free(rp);
 372 }
 373
 374 static int rcu_no_completed(void)
 375 {
 376         return 0;
 377 }
 378
 379 static void rcu_torture_deferred_free(struct rcu_torture *p)
 380 {
 381         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 382 }
 383
 384 static struct rcu_torture_ops rcu_ops = {
 385         .init           = NULL,
 386         .cleanup        = NULL,
 387         .readlock       = rcu_torture_read_lock,
 388         .read_delay     = rcu_read_delay,
 389         .readunlock     = rcu_torture_read_unlock,
 390         .completed      = rcu_torture_completed,
 391         .deferred_free  = rcu_torture_deferred_free,
 392         .sync           = synchronize_rcu,
 393         .cb_barrier     = rcu_barrier,
 394         .fqs            = rcu_force_quiescent_state,
 395         .stats          = NULL,
 396         .irq_capable    = 1,
 397         .can_boost      = rcu_can_boost(),
 398         .name           = "rcu"
 399 };
 400
 401 static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
 402 {
 403         int i;
 404         struct rcu_torture *rp;
 405         struct rcu_torture *rp1;
 406
 407         cur_ops->sync();
 408         list_add(&p->rtort_free, &rcu_torture_removed);
 409         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 410                 i = rp->rtort_pipe_count;
 411                 if (i > RCU_TORTURE_PIPE_LEN)
 412                         i = RCU_TORTURE_PIPE_LEN;
 413                 atomic_inc(&rcu_torture_wcount[i]);
 414                 if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 415                         rp->rtort_mbtest = 0;
 416                         list_del(&rp->rtort_free);
 417                         rcu_torture_free(rp);
 418                 }
 419         }
 420 }
 421
 422 static void rcu_sync_torture_init(void)
 423 {
 424         INIT_LIST_HEAD(&rcu_torture_removed);
 425 }
 426
 427 static struct rcu_torture_ops rcu_sync_ops = {
 428         .init           = rcu_sync_torture_init,
 429         .cleanup        = NULL,
 430         .readlock       = rcu_torture_read_lock,
 431         .read_delay     = rcu_read_delay,
 432         .readunlock     = rcu_torture_read_unlock,
 433         .completed      = rcu_torture_completed,
 434         .deferred_free  = rcu_sync_torture_deferred_free,
 435         .sync           = synchronize_rcu,
 436         .cb_barrier     = NULL,
 437         .fqs            = rcu_force_quiescent_state,
 438         .stats          = NULL,
 439         .irq_capable    = 1,
 440         .can_boost      = rcu_can_boost(),
 441         .name           = "rcu_sync"
 442 };
 443
 444 static struct rcu_torture_ops rcu_expedited_ops = {
 445         .init           = rcu_sync_torture_init,
 446         .cleanup        = NULL,
 447         .readlock       = rcu_torture_read_lock,
 448         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 449         .readunlock     = rcu_torture_read_unlock,
 450         .completed      = rcu_no_completed,
 451         .deferred_free  = rcu_sync_torture_deferred_free,
 452         .sync           = synchronize_rcu_expedited,
 453         .cb_barrier     = NULL,
 454         .fqs            = rcu_force_quiescent_state,
 455         .stats          = NULL,
 456         .irq_capable    = 1,
 457         .can_boost      = rcu_can_boost(),
 458         .name           = "rcu_expedited"
 459 };
 460
 461 /*
 462  * Definitions for rcu_bh torture testing.
 463  */
 464
 465 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
 466 {
 467         rcu_read_lock_bh();
 468         return 0;
 469 }
 470
 471 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
 472 {
 473         rcu_read_unlock_bh();
 474 }
 475
 476 static int rcu_bh_torture_completed(void)
 477 {
 478         return rcu_batches_completed_bh();
 479 }
 480
 481 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 482 {
 483         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
 484 }
 485
 486 struct rcu_bh_torture_synchronize {
 487         struct rcu_head head;
 488         struct completion completion;
 489 };
 490
 491 static void rcu_bh_torture_wakeme_after_cb(struct rcu_head *head)
 492 {
 493         struct rcu_bh_torture_synchronize *rcu;
 494
 495         rcu = container_of(head, struct rcu_bh_torture_synchronize, head);
 496         complete(&rcu->completion);
 497 }
 498
 499 static void rcu_bh_torture_synchronize(void)
 500 {
 501         struct rcu_bh_torture_synchronize rcu;
 502
 503         init_rcu_head_on_stack(&rcu.head);
 504         init_completion(&rcu.completion);
 505         call_rcu_bh(&rcu.head, rcu_bh_torture_wakeme_after_cb);
 506         wait_for_completion(&rcu.completion);
 507         destroy_rcu_head_on_stack(&rcu.head);
 508 }
 509
 510 static struct rcu_torture_ops rcu_bh_ops = {
 511         .init           = NULL,
 512         .cleanup        = NULL,
 513         .readlock       = rcu_bh_torture_read_lock,
 514         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 515         .readunlock     = rcu_bh_torture_read_unlock,
 516         .completed      = rcu_bh_torture_completed,
 517         .deferred_free  = rcu_bh_torture_deferred_free,
 518         .sync           = rcu_bh_torture_synchronize,
 519         .cb_barrier     = rcu_barrier_bh,
 520         .fqs            = rcu_bh_force_quiescent_state,
 521         .stats          = NULL,
 522         .irq_capable    = 1,
 523         .name           = "rcu_bh"
 524 };
 525
 526 static struct rcu_torture_ops rcu_bh_sync_ops = {
 527         .init           = rcu_sync_torture_init,
 528         .cleanup        = NULL,
 529         .readlock       = rcu_bh_torture_read_lock,
 530         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 531         .readunlock     = rcu_bh_torture_read_unlock,
 532         .completed      = rcu_bh_torture_completed,
 533         .deferred_free  = rcu_sync_torture_deferred_free,
 534         .sync           = rcu_bh_torture_synchronize,
 535         .cb_barrier     = NULL,
 536         .fqs            = rcu_bh_force_quiescent_state,
 537         .stats          = NULL,
 538         .irq_capable    = 1,
 539         .name           = "rcu_bh_sync"
 540 };
 541
 542 /*
 543  * Definitions for srcu torture testing.
 544  */
 545
 546 static struct srcu_struct srcu_ctl;
 547
 548 static void srcu_torture_init(void)
 549 {
 550         init_srcu_struct(&srcu_ctl);
 551         rcu_sync_torture_init();
 552 }
 553
 554 static void srcu_torture_cleanup(void)
 555 {
 556         synchronize_srcu(&srcu_ctl);
 557         cleanup_srcu_struct(&srcu_ctl);
 558 }
 559
 560 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
 561 {
 562         return srcu_read_lock(&srcu_ctl);
 563 }
 564
 565 static void srcu_read_delay(struct rcu_random_state *rrsp)
 566 {
 567         long delay;
 568         const long uspertick = 1000000 / HZ;
 569         const long longdelay = 10;
 570
 571         /* We want there to be long-running readers, but not all the time. */
 572
 573         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
 574         if (!delay)
 575                 schedule_timeout_interruptible(longdelay);
 576         else
 577                 rcu_read_delay(rrsp);
 578 }
 579
 580 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
 581 {
 582         srcu_read_unlock(&srcu_ctl, idx);
 583 }
 584
 585 static int srcu_torture_completed(void)
 586 {
 587         return srcu_batches_completed(&srcu_ctl);
 588 }
 589
 590 static void srcu_torture_synchronize(void)
 591 {
 592         synchronize_srcu(&srcu_ctl);
 593 }
 594
 595 static int srcu_torture_stats(char *page)
 596 {
 597         int cnt = 0;
 598         int cpu;
 599         int idx = srcu_ctl.completed & 0x1;
 600
 601         cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
 602                        torture_type, TORTURE_FLAG, idx);
 603         for_each_possible_cpu(cpu) {
 604                 cnt += sprintf(&page[cnt], " %d(%d,%d)", cpu,
 605                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
 606                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
 607         }
 608         cnt += sprintf(&page[cnt], "\n");
 609         return cnt;
 610 }
 611
 612 static struct rcu_torture_ops srcu_ops = {
 613         .init           = srcu_torture_init,
 614         .cleanup        = srcu_torture_cleanup,
 615         .readlock       = srcu_torture_read_lock,
 616         .read_delay     = srcu_read_delay,
 617         .readunlock     = srcu_torture_read_unlock,
 618         .completed      = srcu_torture_completed,
 619         .deferred_free  = rcu_sync_torture_deferred_free,
 620         .sync           = srcu_torture_synchronize,
 621         .cb_barrier     = NULL,
 622         .stats          = srcu_torture_stats,
 623         .name           = "srcu"
 624 };
 625
 626 static void srcu_torture_synchronize_expedited(void)
 627 {
 628         synchronize_srcu_expedited(&srcu_ctl);
 629 }
 630
 631 static struct rcu_torture_ops srcu_expedited_ops = {
 632         .init           = srcu_torture_init,
 633         .cleanup        = srcu_torture_cleanup,
 634         .readlock       = srcu_torture_read_lock,
 635         .read_delay     = srcu_read_delay,
 636         .readunlock     = srcu_torture_read_unlock,
 637         .completed      = srcu_torture_completed,
 638         .deferred_free  = rcu_sync_torture_deferred_free,
 639         .sync           = srcu_torture_synchronize_expedited,
 640         .cb_barrier     = NULL,
 641         .stats          = srcu_torture_stats,
 642         .name           = "srcu_expedited"
 643 };
 644
 645 /*
 646  * Definitions for sched torture testing.
 647  */
 648
 649 static int sched_torture_read_lock(void)
 650 {
 651         preempt_disable();
 652         return 0;
 653 }
 654
 655 static void sched_torture_read_unlock(int idx)
 656 {
 657         preempt_enable();
 658 }
 659
 660 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
 661 {
 662         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
 663 }
 664
 665 static void sched_torture_synchronize(void)
 666 {
 667         synchronize_sched();
 668 }
 669
 670 static struct rcu_torture_ops sched_ops = {
 671         .init           = rcu_sync_torture_init,
 672         .cleanup        = NULL,
 673         .readlock       = sched_torture_read_lock,
 674         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 675         .readunlock     = sched_torture_read_unlock,
 676         .completed      = rcu_no_completed,
 677         .deferred_free  = rcu_sched_torture_deferred_free,
 678         .sync           = sched_torture_synchronize,
 679         .cb_barrier     = rcu_barrier_sched,
 680         .fqs            = rcu_sched_force_quiescent_state,
 681         .stats          = NULL,
 682         .irq_capable    = 1,
 683         .name           = "sched"
 684 };
 685
 686 static struct rcu_torture_ops sched_sync_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           = sched_torture_synchronize,
 695         .cb_barrier     = NULL,
 696         .fqs            = rcu_sched_force_quiescent_state,
 697         .stats          = NULL,
 698         .name           = "sched_sync"
 699 };
 700
 701 static struct rcu_torture_ops sched_expedited_ops = {
 702         .init           = rcu_sync_torture_init,
 703         .cleanup        = NULL,
 704         .readlock       = sched_torture_read_lock,
 705         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 706         .readunlock     = sched_torture_read_unlock,
 707         .completed      = rcu_no_completed,
 708         .deferred_free  = rcu_sync_torture_deferred_free,
 709         .sync           = synchronize_sched_expedited,
 710         .cb_barrier     = NULL,
 711         .fqs            = rcu_sched_force_quiescent_state,
 712         .stats          = NULL,
 713         .irq_capable    = 1,
 714         .name           = "sched_expedited"
 715 };
 716
 717 /*
 718  * RCU torture priority-boost testing.  Runs one real-time thread per
 719  * CPU for moderate bursts, repeatedly registering RCU callbacks and
 720  * spinning waiting for them to be invoked.  If a given callback takes
 721  * too long to be invoked, we assume that priority inversion has occurred.
 722  */
 723
 724 struct rcu_boost_inflight {
 725         struct rcu_head rcu;
 726         int inflight;
 727 };
 728
 729 static void rcu_torture_boost_cb(struct rcu_head *head)
 730 {
 731         struct rcu_boost_inflight *rbip =
 732                 container_of(head, struct rcu_boost_inflight, rcu);
 733
 734         smp_mb(); /* Ensure RCU-core accesses precede clearing ->inflight */
 735         rbip->inflight = 0;
 736 }
 737
 738 static int rcu_torture_boost(void *arg)
 739 {
 740         unsigned long call_rcu_time;
 741         unsigned long endtime;
 742         unsigned long oldstarttime;
 743         struct rcu_boost_inflight rbi = { .inflight = 0 };
 744         struct sched_param sp;
 745
 746         VERBOSE_PRINTK_STRING("rcu_torture_boost started");
 747
 748         /* Set real-time priority. */
 749         sp.sched_priority = 1;
 750         if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 751                 VERBOSE_PRINTK_STRING("rcu_torture_boost RT prio failed!");
 752                 n_rcu_torture_boost_rterror++;
 753         }
 754
 755         /* Each pass through the following loop does one boost-test cycle. */
 756         do {
 757                 /* Wait for the next test interval. */
 758                 oldstarttime = boost_starttime;
 759                 while (jiffies - oldstarttime > ULONG_MAX / 2) {
 760                         schedule_timeout_uninterruptible(1);
 761                         rcu_stutter_wait("rcu_torture_boost");
 762                         if (kthread_should_stop() ||
 763                             fullstop != FULLSTOP_DONTSTOP)
 764                                 goto checkwait;
 765                 }
 766
 767                 /* Do one boost-test interval. */
 768                 endtime = oldstarttime + test_boost_duration * HZ;
 769                 call_rcu_time = jiffies;
 770                 while (jiffies - endtime > ULONG_MAX / 2) {
 771                         /* If we don't have a callback in flight, post one. */
 772                         if (!rbi.inflight) {
 773                                 smp_mb(); /* RCU core before ->inflight = 1. */
 774                                 rbi.inflight = 1;
 775                                 call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 776                                 if (jiffies - call_rcu_time >
 777                                          test_boost_duration * HZ - HZ / 2) {
 778                                         VERBOSE_PRINTK_STRING("rcu_torture_boost boosting failed");
 779                                         n_rcu_torture_boost_failure++;
 780                                 }
 781                                 call_rcu_time = jiffies;
 782                         }
 783                         cond_resched();
 784                         rcu_stutter_wait("rcu_torture_boost");
 785                         if (kthread_should_stop() ||
 786                             fullstop != FULLSTOP_DONTSTOP)
 787                                 goto checkwait;
 788                 }
 789
 790                 /*
 791                  * Set the start time of the next test interval.
 792                  * Yes, this is vulnerable to long delays, but such
 793                  * delays simply cause a false negative for the next
 794                  * interval.  Besides, we are running at RT priority,
 795                  * so delays should be relatively rare.
 796                  */
 797                 while (oldstarttime == boost_starttime) {
 798                         if (mutex_trylock(&boost_mutex)) {
 799                                 boost_starttime = jiffies +
 800                                                   test_boost_interval * HZ;
 801                                 n_rcu_torture_boosts++;
 802                                 mutex_unlock(&boost_mutex);
 803                                 break;
 804                         }
 805                         schedule_timeout_uninterruptible(1);
 806                 }
 807
 808                 /* Go do the stutter. */
 809 checkwait:      rcu_stutter_wait("rcu_torture_boost");
 810         } while (!kthread_should_stop() && fullstop  == FULLSTOP_DONTSTOP);
 811
 812         /* Clean up and exit. */
 813         VERBOSE_PRINTK_STRING("rcu_torture_boost task stopping");
 814         rcutorture_shutdown_absorb("rcu_torture_boost");
 815         while (!kthread_should_stop() || rbi.inflight)
 816                 schedule_timeout_uninterruptible(1);
 817         smp_mb(); /* order accesses to ->inflight before stack-frame death. */
 818         return 0;
 819 }
 820
 821 /*
 822  * RCU torture force-quiescent-state kthread.  Repeatedly induces
 823  * bursts of calls to force_quiescent_state(), increasing the probability
 824  * of occurrence of some important types of race conditions.
 825  */
 826 static int
 827 rcu_torture_fqs(void *arg)
 828 {
 829         unsigned long fqs_resume_time;
 830         int fqs_burst_remaining;
 831
 832         VERBOSE_PRINTK_STRING("rcu_torture_fqs task started");
 833         do {
 834                 fqs_resume_time = jiffies + fqs_stutter * HZ;
 835                 while (jiffies - fqs_resume_time > LONG_MAX) {
 836                         schedule_timeout_interruptible(1);
 837                 }
 838                 fqs_burst_remaining = fqs_duration;
 839                 while (fqs_burst_remaining > 0) {
 840                         cur_ops->fqs();
 841                         udelay(fqs_holdoff);
 842                         fqs_burst_remaining -= fqs_holdoff;
 843                 }
 844                 rcu_stutter_wait("rcu_torture_fqs");
 845         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 846         VERBOSE_PRINTK_STRING("rcu_torture_fqs task stopping");
 847         rcutorture_shutdown_absorb("rcu_torture_fqs");
 848         while (!kthread_should_stop())
 849                 schedule_timeout_uninterruptible(1);
 850         return 0;
 851 }
 852
 853 /*
 854  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 855  * for that pointed to by rcu_torture_current, freeing the old structure
 856  * after a series of grace periods (the "pipeline").
 857  */
 858 static int
 859 rcu_torture_writer(void *arg)
 860 {
 861         int i;
 862         long oldbatch = rcu_batches_completed();
 863         struct rcu_torture *rp;
 864         struct rcu_torture *old_rp;
 865         static DEFINE_RCU_RANDOM(rand);
 866
 867         VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
 868         set_user_nice(current, 19);
 869
 870         do {
 871                 schedule_timeout_uninterruptible(1);
 872                 rp = rcu_torture_alloc();
 873                 if (rp == NULL)
 874                         continue;
 875                 rp->rtort_pipe_count = 0;
 876                 udelay(rcu_random(&rand) & 0x3ff);
 877                 old_rp = rcu_dereference_check(rcu_torture_current,
 878                                                current == writer_task);
 879                 rp->rtort_mbtest = 1;
 880                 rcu_assign_pointer(rcu_torture_current, rp);
 881                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
 882                 if (old_rp) {
 883                         i = old_rp->rtort_pipe_count;
 884                         if (i > RCU_TORTURE_PIPE_LEN)
 885                                 i = RCU_TORTURE_PIPE_LEN;
 886                         atomic_inc(&rcu_torture_wcount[i]);
 887                         old_rp->rtort_pipe_count++;
 888                         cur_ops->deferred_free(old_rp);
 889                 }
 890                 rcu_torture_current_version++;
 891                 oldbatch = cur_ops->completed();
 892                 rcu_stutter_wait("rcu_torture_writer");
 893         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 894         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
 895         rcutorture_shutdown_absorb("rcu_torture_writer");
 896         while (!kthread_should_stop())
 897                 schedule_timeout_uninterruptible(1);
 898         return 0;
 899 }
 900
 901 /*
 902  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
 903  * delay between calls.
 904  */
 905 static int
 906 rcu_torture_fakewriter(void *arg)
 907 {
 908         DEFINE_RCU_RANDOM(rand);
 909
 910         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
 911         set_user_nice(current, 19);
 912
 913         do {
 914                 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
 915                 udelay(rcu_random(&rand) & 0x3ff);
 916                 cur_ops->sync();
 917                 rcu_stutter_wait("rcu_torture_fakewriter");
 918         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 919
 920         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
 921         rcutorture_shutdown_absorb("rcu_torture_fakewriter");
 922         while (!kthread_should_stop())
 923                 schedule_timeout_uninterruptible(1);
 924         return 0;
 925 }
 926
 927 /*
 928  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
 929  * incrementing the corresponding element of the pipeline array.  The
 930  * counter in the element should never be greater than 1, otherwise, the
 931  * RCU implementation is broken.
 932  */
 933 static void rcu_torture_timer(unsigned long unused)
 934 {
 935         int idx;
 936         int completed;
 937         static DEFINE_RCU_RANDOM(rand);
 938         static DEFINE_SPINLOCK(rand_lock);
 939         struct rcu_torture *p;
 940         int pipe_count;
 941
 942         idx = cur_ops->readlock();
 943         completed = cur_ops->completed();
 944         p = rcu_dereference_check(rcu_torture_current,
 945                                   rcu_read_lock_held() ||
 946                                   rcu_read_lock_bh_held() ||
 947                                   rcu_read_lock_sched_held() ||
 948                                   srcu_read_lock_held(&srcu_ctl));
 949         if (p == NULL) {
 950                 /* Leave because rcu_torture_writer is not yet underway */
 951                 cur_ops->readunlock(idx);
 952                 return;
 953         }
 954         if (p->rtort_mbtest == 0)
 955                 atomic_inc(&n_rcu_torture_mberror);
 956         spin_lock(&rand_lock);
 957         cur_ops->read_delay(&rand);
 958         n_rcu_torture_timers++;
 959         spin_unlock(&rand_lock);
 960         preempt_disable();
 961         pipe_count = p->rtort_pipe_count;
 962         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
 963                 /* Should not happen, but... */
 964                 pipe_count = RCU_TORTURE_PIPE_LEN;
 965         }
 966         __this_cpu_inc(rcu_torture_count[pipe_count]);
 967         completed = cur_ops->completed() - completed;
 968         if (completed > RCU_TORTURE_PIPE_LEN) {
 969                 /* Should not happen, but... */
 970                 completed = RCU_TORTURE_PIPE_LEN;
 971         }
 972         __this_cpu_inc(rcu_torture_batch[completed]);
 973         preempt_enable();
 974         cur_ops->readunlock(idx);
 975 }
 976
 977 /*
 978  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
 979  * incrementing the corresponding element of the pipeline array.  The
 980  * counter in the element should never be greater than 1, otherwise, the
 981  * RCU implementation is broken.
 982  */
 983 static int
 984 rcu_torture_reader(void *arg)
 985 {
 986         int completed;
 987         int idx;
 988         DEFINE_RCU_RANDOM(rand);
 989         struct rcu_torture *p;
 990         int pipe_count;
 991         struct timer_list t;
 992
 993         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
 994         set_user_nice(current, 19);
 995         if (irqreader && cur_ops->irq_capable)
 996                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
 997
 998         do {
 999                 if (irqreader && cur_ops->irq_capable) {
1000                         if (!timer_pending(&t))
1001                                 mod_timer(&t, jiffies + 1);
1002                 }
1003                 idx = cur_ops->readlock();
1004                 completed = cur_ops->completed();
1005                 p = rcu_dereference_check(rcu_torture_current,
1006                                           rcu_read_lock_held() ||
1007                                           rcu_read_lock_bh_held() ||
1008                                           rcu_read_lock_sched_held() ||
1009                                           srcu_read_lock_held(&srcu_ctl));
1010                 if (p == NULL) {
1011                         /* Wait for rcu_torture_writer to get underway */
1012                         cur_ops->readunlock(idx);
1013                         schedule_timeout_interruptible(HZ);
1014                         continue;
1015                 }
1016                 if (p->rtort_mbtest == 0)
1017                         atomic_inc(&n_rcu_torture_mberror);
1018                 cur_ops->read_delay(&rand);
1019                 preempt_disable();
1020                 pipe_count = p->rtort_pipe_count;
1021                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1022                         /* Should not happen, but... */
1023                         pipe_count = RCU_TORTURE_PIPE_LEN;
1024                 }
1025                 __this_cpu_inc(rcu_torture_count[pipe_count]);
1026                 completed = cur_ops->completed() - completed;
1027                 if (completed > RCU_TORTURE_PIPE_LEN) {
1028                         /* Should not happen, but... */
1029                         completed = RCU_TORTURE_PIPE_LEN;
1030                 }
1031                 __this_cpu_inc(rcu_torture_batch[completed]);
1032                 preempt_enable();
1033                 cur_ops->readunlock(idx);
1034                 schedule();
1035                 rcu_stutter_wait("rcu_torture_reader");
1036         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1037         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
1038         rcutorture_shutdown_absorb("rcu_torture_reader");
1039         if (irqreader && cur_ops->irq_capable)
1040                 del_timer_sync(&t);
1041         while (!kthread_should_stop())
1042                 schedule_timeout_uninterruptible(1);
1043         return 0;
1044 }
1045
1046 /*
1047  * Create an RCU-torture statistics message in the specified buffer.
1048  */
1049 static int
1050 rcu_torture_printk(char *page)
1051 {
1052         int cnt = 0;
1053         int cpu;
1054         int i;
1055         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1056         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1057
1058         for_each_possible_cpu(cpu) {
1059                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1060                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1061                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1062                 }
1063         }
1064         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1065                 if (pipesummary[i] != 0)
1066                         break;
1067         }
1068         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
1069         cnt += sprintf(&page[cnt],
1070                        "rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d "
1071                        "rtmbe: %d rtbke: %ld rtbre: %ld rtbae: %ld rtbafe: %ld "
1072                        "rtbf: %ld rtb: %ld nt: %ld",
1073                        rcu_torture_current,
1074                        rcu_torture_current_version,
1075                        list_empty(&rcu_torture_freelist),
1076                        atomic_read(&n_rcu_torture_alloc),
1077                        atomic_read(&n_rcu_torture_alloc_fail),
1078                        atomic_read(&n_rcu_torture_free),
1079                        atomic_read(&n_rcu_torture_mberror),
1080                        n_rcu_torture_boost_ktrerror,
1081                        n_rcu_torture_boost_rterror,
1082                        n_rcu_torture_boost_allocerror,
1083                        n_rcu_torture_boost_afferror,
1084                        n_rcu_torture_boost_failure,
1085                        n_rcu_torture_boosts,
1086                        n_rcu_torture_timers);
1087         if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1088             n_rcu_torture_boost_ktrerror != 0 ||
1089             n_rcu_torture_boost_rterror != 0 ||
1090             n_rcu_torture_boost_allocerror != 0 ||
1091             n_rcu_torture_boost_afferror != 0 ||
1092             n_rcu_torture_boost_failure != 0)
1093                 cnt += sprintf(&page[cnt], " !!!");
1094         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1095         if (i > 1) {
1096                 cnt += sprintf(&page[cnt], "!!! ");
1097                 atomic_inc(&n_rcu_torture_error);
1098                 WARN_ON_ONCE(1);
1099         }
1100         cnt += sprintf(&page[cnt], "Reader Pipe: ");
1101         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1102                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
1103         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1104         cnt += sprintf(&page[cnt], "Reader Batch: ");
1105         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1106                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
1107         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1108         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
1109         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1110                 cnt += sprintf(&page[cnt], " %d",
1111                                atomic_read(&rcu_torture_wcount[i]));
1112         }
1113         cnt += sprintf(&page[cnt], "\n");
1114         if (cur_ops->stats)
1115                 cnt += cur_ops->stats(&page[cnt]);
1116         return cnt;
1117 }
1118
1119 /*
1120  * Print torture statistics.  Caller must ensure that there is only
1121  * one call to this function at a given time!!!  This is normally
1122  * accomplished by relying on the module system to only have one copy
1123  * of the module loaded, and then by giving the rcu_torture_stats
1124  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1125  * thread is not running).
1126  */
1127 static void
1128 rcu_torture_stats_print(void)
1129 {
1130         int cnt;
1131
1132         cnt = rcu_torture_printk(printk_buf);
1133         printk(KERN_ALERT "%s", printk_buf);
1134 }
1135
1136 /*
1137  * Periodically prints torture statistics, if periodic statistics printing
1138  * was specified via the stat_interval module parameter.
1139  *
1140  * No need to worry about fullstop here, since this one doesn't reference
1141  * volatile state or register callbacks.
1142  */
1143 static int
1144 rcu_torture_stats(void *arg)
1145 {
1146         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
1147         do {
1148                 schedule_timeout_interruptible(stat_interval * HZ);
1149                 rcu_torture_stats_print();
1150                 rcutorture_shutdown_absorb("rcu_torture_stats");
1151         } while (!kthread_should_stop());
1152         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
1153         return 0;
1154 }
1155
1156 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
1157
1158 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
1159  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
1160  */
1161 static void rcu_torture_shuffle_tasks(void)
1162 {
1163         int i;
1164
1165         cpumask_setall(shuffle_tmp_mask);
1166         get_online_cpus();
1167
1168         /* No point in shuffling if there is only one online CPU (ex: UP) */
1169         if (num_online_cpus() == 1) {
1170                 put_online_cpus();
1171                 return;
1172         }
1173
1174         if (rcu_idle_cpu != -1)
1175                 cpumask_clear_cpu(rcu_idle_cpu, shuffle_tmp_mask);
1176
1177         set_cpus_allowed_ptr(current, shuffle_tmp_mask);
1178
1179         if (reader_tasks) {
1180                 for (i = 0; i < nrealreaders; i++)
1181                         if (reader_tasks[i])
1182                                 set_cpus_allowed_ptr(reader_tasks[i],
1183                                                      shuffle_tmp_mask);
1184         }
1185
1186         if (fakewriter_tasks) {
1187                 for (i = 0; i < nfakewriters; i++)
1188                         if (fakewriter_tasks[i])
1189                                 set_cpus_allowed_ptr(fakewriter_tasks[i],
1190                                                      shuffle_tmp_mask);
1191         }
1192
1193         if (writer_task)
1194                 set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
1195
1196         if (stats_task)
1197                 set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
1198
1199         if (rcu_idle_cpu == -1)
1200                 rcu_idle_cpu = num_online_cpus() - 1;
1201         else
1202                 rcu_idle_cpu--;
1203
1204         put_online_cpus();
1205 }
1206
1207 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
1208  * system to become idle at a time and cut off its timer ticks. This is meant
1209  * to test the support for such tickless idle CPU in RCU.
1210  */
1211 static int
1212 rcu_torture_shuffle(void *arg)
1213 {
1214         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
1215         do {
1216                 schedule_timeout_interruptible(shuffle_interval * HZ);
1217                 rcu_torture_shuffle_tasks();
1218                 rcutorture_shutdown_absorb("rcu_torture_shuffle");
1219         } while (!kthread_should_stop());
1220         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
1221         return 0;
1222 }
1223
1224 /* Cause the rcutorture test to "stutter", starting and stopping all
1225  * threads periodically.
1226  */
1227 static int
1228 rcu_torture_stutter(void *arg)
1229 {
1230         VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
1231         do {
1232                 schedule_timeout_interruptible(stutter * HZ);
1233                 stutter_pause_test = 1;
1234                 if (!kthread_should_stop())
1235                         schedule_timeout_interruptible(stutter * HZ);
1236                 stutter_pause_test = 0;
1237                 rcutorture_shutdown_absorb("rcu_torture_stutter");
1238         } while (!kthread_should_stop());
1239         VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
1240         return 0;
1241 }
1242
1243 static inline void
1244 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, char *tag)
1245 {
1246         printk(KERN_ALERT "%s" TORTURE_FLAG
1247                 "--- %s: nreaders=%d nfakewriters=%d "
1248                 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1249                 "shuffle_interval=%d stutter=%d irqreader=%d "
1250                 "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1251                 "test_boost=%d/%d test_boost_interval=%d "
1252                 "test_boost_duration=%d\n",
1253                 torture_type, tag, nrealreaders, nfakewriters,
1254                 stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1255                 stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1256                 test_boost, cur_ops->can_boost,
1257                 test_boost_interval, test_boost_duration);
1258 }
1259
1260 static struct notifier_block rcutorture_shutdown_nb = {
1261         .notifier_call = rcutorture_shutdown_notify,
1262 };
1263
1264 static void rcutorture_booster_cleanup(int cpu)
1265 {
1266         struct task_struct *t;
1267
1268         if (boost_tasks[cpu] == NULL)
1269                 return;
1270         mutex_lock(&boost_mutex);
1271         VERBOSE_PRINTK_STRING("Stopping rcu_torture_boost task");
1272         t = boost_tasks[cpu];
1273         boost_tasks[cpu] = NULL;
1274         mutex_unlock(&boost_mutex);
1275
1276         /* This must be outside of the mutex, otherwise deadlock! */
1277         kthread_stop(t);
1278 }
1279
1280 static int rcutorture_booster_init(int cpu)
1281 {
1282         int retval;
1283
1284         if (boost_tasks[cpu] != NULL)
1285                 return 0;  /* Already created, nothing more to do. */
1286
1287         /* Don't allow time recalculation while creating a new task. */
1288         mutex_lock(&boost_mutex);
1289         VERBOSE_PRINTK_STRING("Creating rcu_torture_boost task");
1290         boost_tasks[cpu] = kthread_create(rcu_torture_boost, NULL,
1291                                           "rcu_torture_boost");
1292         if (IS_ERR(boost_tasks[cpu])) {
1293                 retval = PTR_ERR(boost_tasks[cpu]);
1294                 VERBOSE_PRINTK_STRING("rcu_torture_boost task create failed");
1295                 n_rcu_torture_boost_ktrerror++;
1296                 boost_tasks[cpu] = NULL;
1297                 mutex_unlock(&boost_mutex);
1298                 return retval;
1299         }
1300         kthread_bind(boost_tasks[cpu], cpu);
1301         wake_up_process(boost_tasks[cpu]);
1302         mutex_unlock(&boost_mutex);
1303         return 0;
1304 }
1305
1306 static int rcutorture_cpu_notify(struct notifier_block *self,
1307                                  unsigned long action, void *hcpu)
1308 {
1309         long cpu = (long)hcpu;
1310
1311         switch (action) {
1312         case CPU_ONLINE:
1313         case CPU_DOWN_FAILED:
1314                 (void)rcutorture_booster_init(cpu);
1315                 break;
1316         case CPU_DOWN_PREPARE:
1317                 rcutorture_booster_cleanup(cpu);
1318                 break;
1319         default:
1320                 break;
1321         }
1322         return NOTIFY_OK;
1323 }
1324
1325 static struct notifier_block rcutorture_cpu_nb = {
1326         .notifier_call = rcutorture_cpu_notify,
1327 };
1328
1329 static void
1330 rcu_torture_cleanup(void)
1331 {
1332         int i;
1333
1334         mutex_lock(&fullstop_mutex);
1335         if (fullstop == FULLSTOP_SHUTDOWN) {
1336                 printk(KERN_WARNING /* but going down anyway, so... */
1337                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
1338                 mutex_unlock(&fullstop_mutex);
1339                 schedule_timeout_uninterruptible(10);
1340                 if (cur_ops->cb_barrier != NULL)
1341                         cur_ops->cb_barrier();
1342                 return;
1343         }
1344         fullstop = FULLSTOP_RMMOD;
1345         mutex_unlock(&fullstop_mutex);
1346         unregister_reboot_notifier(&rcutorture_shutdown_nb);
1347         if (stutter_task) {
1348                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
1349                 kthread_stop(stutter_task);
1350         }
1351         stutter_task = NULL;
1352         if (shuffler_task) {
1353                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
1354                 kthread_stop(shuffler_task);
1355                 free_cpumask_var(shuffle_tmp_mask);
1356         }
1357         shuffler_task = NULL;
1358
1359         if (writer_task) {
1360                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
1361                 kthread_stop(writer_task);
1362         }
1363         writer_task = NULL;
1364
1365         if (reader_tasks) {
1366                 for (i = 0; i < nrealreaders; i++) {
1367                         if (reader_tasks[i]) {
1368                                 VERBOSE_PRINTK_STRING(
1369                                         "Stopping rcu_torture_reader task");
1370                                 kthread_stop(reader_tasks[i]);
1371                         }
1372                         reader_tasks[i] = NULL;
1373                 }
1374                 kfree(reader_tasks);
1375                 reader_tasks = NULL;
1376         }
1377         rcu_torture_current = NULL;
1378
1379         if (fakewriter_tasks) {
1380                 for (i = 0; i < nfakewriters; i++) {
1381                         if (fakewriter_tasks[i]) {
1382                                 VERBOSE_PRINTK_STRING(
1383                                         "Stopping rcu_torture_fakewriter task");
1384                                 kthread_stop(fakewriter_tasks[i]);
1385                         }
1386                         fakewriter_tasks[i] = NULL;
1387                 }
1388                 kfree(fakewriter_tasks);
1389                 fakewriter_tasks = NULL;
1390         }
1391
1392         if (stats_task) {
1393                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
1394                 kthread_stop(stats_task);
1395         }
1396         stats_task = NULL;
1397
1398         if (fqs_task) {
1399                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_fqs task");
1400                 kthread_stop(fqs_task);
1401         }
1402         fqs_task = NULL;
1403         if ((test_boost == 1 && cur_ops->can_boost) ||
1404             test_boost == 2) {
1405                 unregister_cpu_notifier(&rcutorture_cpu_nb);
1406                 for_each_possible_cpu(i)
1407                         rcutorture_booster_cleanup(i);
1408         }
1409
1410         /* Wait for all RCU callbacks to fire.  */
1411
1412         if (cur_ops->cb_barrier != NULL)
1413                 cur_ops->cb_barrier();
1414
1415         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1416
1417         if (cur_ops->cleanup)
1418                 cur_ops->cleanup();
1419         if (atomic_read(&n_rcu_torture_error))
1420                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1421         else
1422                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1423 }
1424
1425 static int __init
1426 rcu_torture_init(void)
1427 {
1428         int i;
1429         int cpu;
1430         int firsterr = 0;
1431         static struct rcu_torture_ops *torture_ops[] =
1432                 { &rcu_ops, &rcu_sync_ops, &rcu_expedited_ops,
1433                   &rcu_bh_ops, &rcu_bh_sync_ops,
1434                   &srcu_ops, &srcu_expedited_ops,
1435                   &sched_ops, &sched_sync_ops, &sched_expedited_ops, };
1436
1437         mutex_lock(&fullstop_mutex);
1438
1439         /* Process args and tell the world that the torturer is on the job. */
1440         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1441                 cur_ops = torture_ops[i];
1442                 if (strcmp(torture_type, cur_ops->name) == 0)
1443                         break;
1444         }
1445         if (i == ARRAY_SIZE(torture_ops)) {
1446                 printk(KERN_ALERT "rcu-torture: invalid torture type: \"%s\"\n",
1447                        torture_type);
1448                 printk(KERN_ALERT "rcu-torture types:");
1449                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1450                         printk(KERN_ALERT " %s", torture_ops[i]->name);
1451                 printk(KERN_ALERT "\n");
1452                 mutex_unlock(&fullstop_mutex);
1453                 return -EINVAL;
1454         }
1455         if (cur_ops->fqs == NULL && fqs_duration != 0) {
1456                 printk(KERN_ALERT "rcu-torture: ->fqs NULL and non-zero "
1457                                   "fqs_duration, fqs disabled.\n");
1458                 fqs_duration = 0;
1459         }
1460         if (cur_ops->init)
1461                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1462
1463         if (nreaders >= 0)
1464                 nrealreaders = nreaders;
1465         else
1466                 nrealreaders = 2 * num_online_cpus();
1467         rcu_torture_print_module_parms(cur_ops, "Start of test");
1468         fullstop = FULLSTOP_DONTSTOP;
1469
1470         /* Set up the freelist. */
1471
1472         INIT_LIST_HEAD(&rcu_torture_freelist);
1473         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1474                 rcu_tortures[i].rtort_mbtest = 0;
1475                 list_add_tail(&rcu_tortures[i].rtort_free,
1476                               &rcu_torture_freelist);
1477         }
1478
1479         /* Initialize the statistics so that each run gets its own numbers. */
1480
1481         rcu_torture_current = NULL;
1482         rcu_torture_current_version = 0;
1483         atomic_set(&n_rcu_torture_alloc, 0);
1484         atomic_set(&n_rcu_torture_alloc_fail, 0);
1485         atomic_set(&n_rcu_torture_free, 0);
1486         atomic_set(&n_rcu_torture_mberror, 0);
1487         atomic_set(&n_rcu_torture_error, 0);
1488         n_rcu_torture_boost_ktrerror = 0;
1489         n_rcu_torture_boost_rterror = 0;
1490         n_rcu_torture_boost_allocerror = 0;
1491         n_rcu_torture_boost_afferror = 0;
1492         n_rcu_torture_boost_failure = 0;
1493         n_rcu_torture_boosts = 0;
1494         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1495                 atomic_set(&rcu_torture_wcount[i], 0);
1496         for_each_possible_cpu(cpu) {
1497                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1498                         per_cpu(rcu_torture_count, cpu)[i] = 0;
1499                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
1500                 }
1501         }
1502
1503         /* Start up the kthreads. */
1504
1505         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
1506         writer_task = kthread_run(rcu_torture_writer, NULL,
1507                                   "rcu_torture_writer");
1508         if (IS_ERR(writer_task)) {
1509                 firsterr = PTR_ERR(writer_task);
1510                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
1511                 writer_task = NULL;
1512                 goto unwind;
1513         }
1514         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1515                                    GFP_KERNEL);
1516         if (fakewriter_tasks == NULL) {
1517                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1518                 firsterr = -ENOMEM;
1519                 goto unwind;
1520         }
1521         for (i = 0; i < nfakewriters; i++) {
1522                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
1523                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
1524                                                   "rcu_torture_fakewriter");
1525                 if (IS_ERR(fakewriter_tasks[i])) {
1526                         firsterr = PTR_ERR(fakewriter_tasks[i]);
1527                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
1528                         fakewriter_tasks[i] = NULL;
1529                         goto unwind;
1530                 }
1531         }
1532         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1533                                GFP_KERNEL);
1534         if (reader_tasks == NULL) {
1535                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1536                 firsterr = -ENOMEM;
1537                 goto unwind;
1538         }
1539         for (i = 0; i < nrealreaders; i++) {
1540                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
1541                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
1542                                               "rcu_torture_reader");
1543                 if (IS_ERR(reader_tasks[i])) {
1544                         firsterr = PTR_ERR(reader_tasks[i]);
1545                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
1546                         reader_tasks[i] = NULL;
1547                         goto unwind;
1548                 }
1549         }
1550         if (stat_interval > 0) {
1551                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
1552                 stats_task = kthread_run(rcu_torture_stats, NULL,
1553                                         "rcu_torture_stats");
1554                 if (IS_ERR(stats_task)) {
1555                         firsterr = PTR_ERR(stats_task);
1556                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
1557                         stats_task = NULL;
1558                         goto unwind;
1559                 }
1560         }
1561         if (test_no_idle_hz) {
1562                 rcu_idle_cpu = num_online_cpus() - 1;
1563
1564                 if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
1565                         firsterr = -ENOMEM;
1566                         VERBOSE_PRINTK_ERRSTRING("Failed to alloc mask");
1567                         goto unwind;
1568                 }
1569
1570                 /* Create the shuffler thread */
1571                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
1572                                           "rcu_torture_shuffle");
1573                 if (IS_ERR(shuffler_task)) {
1574                         free_cpumask_var(shuffle_tmp_mask);
1575                         firsterr = PTR_ERR(shuffler_task);
1576                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
1577                         shuffler_task = NULL;
1578                         goto unwind;
1579                 }
1580         }
1581         if (stutter < 0)
1582                 stutter = 0;
1583         if (stutter) {
1584                 /* Create the stutter thread */
1585                 stutter_task = kthread_run(rcu_torture_stutter, NULL,
1586                                           "rcu_torture_stutter");
1587                 if (IS_ERR(stutter_task)) {
1588                         firsterr = PTR_ERR(stutter_task);
1589                         VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
1590                         stutter_task = NULL;
1591                         goto unwind;
1592                 }
1593         }
1594         if (fqs_duration < 0)
1595                 fqs_duration = 0;
1596         if (fqs_duration) {
1597                 /* Create the stutter thread */
1598                 fqs_task = kthread_run(rcu_torture_fqs, NULL,
1599                                        "rcu_torture_fqs");
1600                 if (IS_ERR(fqs_task)) {
1601                         firsterr = PTR_ERR(fqs_task);
1602                         VERBOSE_PRINTK_ERRSTRING("Failed to create fqs");
1603                         fqs_task = NULL;
1604                         goto unwind;
1605                 }
1606         }
1607         if (test_boost_interval < 1)
1608                 test_boost_interval = 1;
1609         if (test_boost_duration < 2)
1610                 test_boost_duration = 2;
1611         if ((test_boost == 1 && cur_ops->can_boost) ||
1612             test_boost == 2) {
1613                 int retval;
1614
1615                 boost_starttime = jiffies + test_boost_interval * HZ;
1616                 register_cpu_notifier(&rcutorture_cpu_nb);
1617                 for_each_possible_cpu(i) {
1618                         if (cpu_is_offline(i))
1619                                 continue;  /* Heuristic: CPU can go offline. */
1620                         retval = rcutorture_booster_init(i);
1621                         if (retval < 0) {
1622                                 firsterr = retval;
1623                                 goto unwind;
1624                         }
1625                 }
1626         }
1627         register_reboot_notifier(&rcutorture_shutdown_nb);
1628         mutex_unlock(&fullstop_mutex);
1629         return 0;
1630
1631 unwind:
1632         mutex_unlock(&fullstop_mutex);
1633         rcu_torture_cleanup();
1634         return firsterr;
1635 }
1636
1637 module_init(rcu_torture_init);
1638 module_exit(rcu_torture_cleanup);