kernel/rcutorture.c

   1 /*
   2  * Read-Copy Update module-based torture test facility
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  17  *
  18  * Copyright (C) IBM Corporation, 2005, 2006
  19  *
  20  * Authors: Paul E. McKenney <paulmck@us.ibm.com>
  21  *        Josh Triplett <josh@freedesktop.org>
  22  *
  23  * See also:  Documentation/RCU/torture.txt
  24  */
  25 #include <linux/types.h>
  26 #include <linux/kernel.h>
  27 #include <linux/init.h>
  28 #include <linux/module.h>
  29 #include <linux/kthread.h>
  30 #include <linux/err.h>
  31 #include <linux/spinlock.h>
  32 #include <linux/smp.h>
  33 #include <linux/rcupdate.h>
  34 #include <linux/interrupt.h>
  35 #include <linux/sched.h>
  36 #include <linux/atomic.h>
  37 #include <linux/bitops.h>
  38 #include <linux/completion.h>
  39 #include <linux/moduleparam.h>
  40 #include <linux/percpu.h>
  41 #include <linux/notifier.h>
  42 #include <linux/reboot.h>
  43 #include <linux/freezer.h>
  44 #include <linux/cpu.h>
  45 #include <linux/delay.h>
  46 #include <linux/stat.h>
  47 #include <linux/srcu.h>
  48 #include <linux/slab.h>
  49 #include <asm/byteorder.h>
  50
  51 MODULE_LICENSE("GPL");
  52 MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and "
  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;        /* Duration of bursts (us), 0 to disable. */
  65 static int fqs_holdoff;         /* Hold time within burst (us). */
  66 static int fqs_stutter = 3;     /* Wait time between bursts (s). */
  67 static int shutdown_secs;       /* Shutdown time (s).  <=0 for no shutdown. */
  68 static int test_boost = 1;      /* Test RCU prio boost: 0=no, 1=maybe, 2=yes. */
  69 static int test_boost_interval = 7; /* Interval between boost tests, seconds. */
  70 static int test_boost_duration = 4; /* Duration of each boost test, seconds. */
  71 static char *torture_type = "rcu"; /* What RCU implementation to torture. */
  72
  73 module_param(nreaders, int, 0444);
  74 MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
  75 module_param(nfakewriters, int, 0444);
  76 MODULE_PARM_DESC(nfakewriters, "Number of RCU fake writer threads");
  77 module_param(stat_interval, int, 0644);
  78 MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
  79 module_param(verbose, bool, 0444);
  80 MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
  81 module_param(test_no_idle_hz, bool, 0444);
  82 MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
  83 module_param(shuffle_interval, int, 0444);
  84 MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
  85 module_param(stutter, int, 0444);
  86 MODULE_PARM_DESC(stutter, "Number of seconds to run/halt test");
  87 module_param(irqreader, int, 0444);
  88 MODULE_PARM_DESC(irqreader, "Allow RCU readers from irq handlers");
  89 module_param(fqs_duration, int, 0444);
  90 MODULE_PARM_DESC(fqs_duration, "Duration of fqs bursts (us)");
  91 module_param(fqs_holdoff, int, 0444);
  92 MODULE_PARM_DESC(fqs_holdoff, "Holdoff time within fqs bursts (us)");
  93 module_param(fqs_stutter, int, 0444);
  94 MODULE_PARM_DESC(fqs_stutter, "Wait time between fqs bursts (s)");
  95 module_param(shutdown_secs, int, 0444);
  96 MODULE_PARM_DESC(shutdown_secs, "Shutdown time (s), zero to disable.");
  97 module_param(test_boost, int, 0444);
  98 MODULE_PARM_DESC(test_boost, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
  99 module_param(test_boost_interval, int, 0444);
 100 MODULE_PARM_DESC(test_boost_interval, "Interval between boost tests, seconds.");
 101 module_param(test_boost_duration, int, 0444);
 102 MODULE_PARM_DESC(test_boost_duration, "Duration of each boost test, seconds.");
 103 module_param(torture_type, charp, 0444);
 104 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, srcu)");
 105
 106 #define TORTURE_FLAG "-torture:"
 107 #define PRINTK_STRING(s) \
 108         do { printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
 109 #define VERBOSE_PRINTK_STRING(s) \
 110         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
 111 #define VERBOSE_PRINTK_ERRSTRING(s) \
 112         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
 113
 114 static char printk_buf[4096];
 115
 116 static int nrealreaders;
 117 static struct task_struct *writer_task;
 118 static struct task_struct **fakewriter_tasks;
 119 static struct task_struct **reader_tasks;
 120 static struct task_struct *stats_task;
 121 static struct task_struct *shuffler_task;
 122 static struct task_struct *stutter_task;
 123 static struct task_struct *fqs_task;
 124 static struct task_struct *boost_tasks[NR_CPUS];
 125 static struct task_struct *shutdown_task;
 126
 127 #define RCU_TORTURE_PIPE_LEN 10
 128
 129 struct rcu_torture {
 130         struct rcu_head rtort_rcu;
 131         int rtort_pipe_count;
 132         struct list_head rtort_free;
 133         int rtort_mbtest;
 134 };
 135
 136 static LIST_HEAD(rcu_torture_freelist);
 137 static struct rcu_torture __rcu *rcu_torture_current;
 138 static unsigned long rcu_torture_current_version;
 139 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 140 static DEFINE_SPINLOCK(rcu_torture_lock);
 141 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
 142         { 0 };
 143 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) =
 144         { 0 };
 145 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 146 static atomic_t n_rcu_torture_alloc;
 147 static atomic_t n_rcu_torture_alloc_fail;
 148 static atomic_t n_rcu_torture_free;
 149 static atomic_t n_rcu_torture_mberror;
 150 static atomic_t n_rcu_torture_error;
 151 static long n_rcu_torture_boost_ktrerror;
 152 static long n_rcu_torture_boost_rterror;
 153 static long n_rcu_torture_boost_failure;
 154 static long n_rcu_torture_boosts;
 155 static long n_rcu_torture_timers;
 156 static struct list_head rcu_torture_removed;
 157 static cpumask_var_t shuffle_tmp_mask;
 158
 159 static int stutter_pause_test;
 160
 161 #if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
 162 #define RCUTORTURE_RUNNABLE_INIT 1
 163 #else
 164 #define RCUTORTURE_RUNNABLE_INIT 0
 165 #endif
 166 int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT;
 167
 168 #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
 169 #define rcu_can_boost() 1
 170 #else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 171 #define rcu_can_boost() 0
 172 #endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 173
 174 static unsigned long shutdown_time;     /* jiffies to system shutdown. */
 175 static unsigned long boost_starttime;   /* jiffies of next boost test start. */
 176 DEFINE_MUTEX(boost_mutex);              /* protect setting boost_starttime */
 177                                         /*  and boost task create/destroy. */
 178
 179 /* Mediate rmmod and system shutdown.  Concurrent rmmod & shutdown illegal! */
 180
 181 #define FULLSTOP_DONTSTOP 0     /* Normal operation. */
 182 #define FULLSTOP_SHUTDOWN 1     /* System shutdown with rcutorture running. */
 183 #define FULLSTOP_RMMOD    2     /* Normal rmmod of rcutorture. */
 184 static int fullstop = FULLSTOP_RMMOD;
 185 /*
 186  * Protect fullstop transitions and spawning of kthreads.
 187  */
 188 static DEFINE_MUTEX(fullstop_mutex);
 189
 190 /* Forward reference. */
 191 static void rcu_torture_cleanup(void);
 192
 193 /*
 194  * Detect and respond to a system shutdown.
 195  */
 196 static int
 197 rcutorture_shutdown_notify(struct notifier_block *unused1,
 198                            unsigned long unused2, void *unused3)
 199 {
 200         mutex_lock(&fullstop_mutex);
 201         if (fullstop == FULLSTOP_DONTSTOP)
 202                 fullstop = FULLSTOP_SHUTDOWN;
 203         else
 204                 printk(KERN_WARNING /* but going down anyway, so... */
 205                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
 206         mutex_unlock(&fullstop_mutex);
 207         return NOTIFY_DONE;
 208 }
 209
 210 /*
 211  * Absorb kthreads into a kernel function that won't return, so that
 212  * they won't ever access module text or data again.
 213  */
 214 static void rcutorture_shutdown_absorb(char *title)
 215 {
 216         if (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
 217                 printk(KERN_NOTICE
 218                        "rcutorture thread %s parking due to system shutdown\n",
 219                        title);
 220                 schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
 221         }
 222 }
 223
 224 /*
 225  * Allocate an element from the rcu_tortures pool.
 226  */
 227 static struct rcu_torture *
 228 rcu_torture_alloc(void)
 229 {
 230         struct list_head *p;
 231
 232         spin_lock_bh(&rcu_torture_lock);
 233         if (list_empty(&rcu_torture_freelist)) {
 234                 atomic_inc(&n_rcu_torture_alloc_fail);
 235                 spin_unlock_bh(&rcu_torture_lock);
 236                 return NULL;
 237         }
 238         atomic_inc(&n_rcu_torture_alloc);
 239         p = rcu_torture_freelist.next;
 240         list_del_init(p);
 241         spin_unlock_bh(&rcu_torture_lock);
 242         return container_of(p, struct rcu_torture, rtort_free);
 243 }
 244
 245 /*
 246  * Free an element to the rcu_tortures pool.
 247  */
 248 static void
 249 rcu_torture_free(struct rcu_torture *p)
 250 {
 251         atomic_inc(&n_rcu_torture_free);
 252         spin_lock_bh(&rcu_torture_lock);
 253         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 254         spin_unlock_bh(&rcu_torture_lock);
 255 }
 256
 257 struct rcu_random_state {
 258         unsigned long rrs_state;
 259         long rrs_count;
 260 };
 261
 262 #define RCU_RANDOM_MULT 39916801  /* prime */
 263 #define RCU_RANDOM_ADD  479001701 /* prime */
 264 #define RCU_RANDOM_REFRESH 10000
 265
 266 #define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
 267
 268 /*
 269  * Crude but fast random-number generator.  Uses a linear congruential
 270  * generator, with occasional help from cpu_clock().
 271  */
 272 static unsigned long
 273 rcu_random(struct rcu_random_state *rrsp)
 274 {
 275         if (--rrsp->rrs_count < 0) {
 276                 rrsp->rrs_state += (unsigned long)local_clock();
 277                 rrsp->rrs_count = RCU_RANDOM_REFRESH;
 278         }
 279         rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
 280         return swahw32(rrsp->rrs_state);
 281 }
 282
 283 static void
 284 rcu_stutter_wait(char *title)
 285 {
 286         while (stutter_pause_test || !rcutorture_runnable) {
 287                 if (rcutorture_runnable)
 288                         schedule_timeout_interruptible(1);
 289                 else
 290                         schedule_timeout_interruptible(round_jiffies_relative(HZ));
 291                 rcutorture_shutdown_absorb(title);
 292         }
 293 }
 294
 295 /*
 296  * Operations vector for selecting different types of tests.
 297  */
 298
 299 struct rcu_torture_ops {
 300         void (*init)(void);
 301         void (*cleanup)(void);
 302         int (*readlock)(void);
 303         void (*read_delay)(struct rcu_random_state *rrsp);
 304         void (*readunlock)(int idx);
 305         int (*completed)(void);
 306         void (*deferred_free)(struct rcu_torture *p);
 307         void (*sync)(void);
 308         void (*cb_barrier)(void);
 309         void (*fqs)(void);
 310         int (*stats)(char *page);
 311         int irq_capable;
 312         int can_boost;
 313         char *name;
 314 };
 315
 316 static struct rcu_torture_ops *cur_ops;
 317
 318 /*
 319  * Definitions for rcu torture testing.
 320  */
 321
 322 static int rcu_torture_read_lock(void) __acquires(RCU)
 323 {
 324         rcu_read_lock();
 325         return 0;
 326 }
 327
 328 static void rcu_read_delay(struct rcu_random_state *rrsp)
 329 {
 330         const unsigned long shortdelay_us = 200;
 331         const unsigned long longdelay_ms = 50;
 332
 333         /* We want a short delay sometimes to make a reader delay the grace
 334          * period, and we want a long delay occasionally to trigger
 335          * force_quiescent_state. */
 336
 337         if (!(rcu_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
 338                 mdelay(longdelay_ms);
 339         if (!(rcu_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
 340                 udelay(shortdelay_us);
 341 #ifdef CONFIG_PREEMPT
 342         if (!preempt_count() && !(rcu_random(rrsp) % (nrealreaders * 20000)))
 343                 preempt_schedule();  /* No QS if preempt_disable() in effect */
 344 #endif
 345 }
 346
 347 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 348 {
 349         rcu_read_unlock();
 350 }
 351
 352 static int rcu_torture_completed(void)
 353 {
 354         return rcu_batches_completed();
 355 }
 356
 357 static void
 358 rcu_torture_cb(struct rcu_head *p)
 359 {
 360         int i;
 361         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 362
 363         if (fullstop != FULLSTOP_DONTSTOP) {
 364                 /* Test is ending, just drop callbacks on the floor. */
 365                 /* The next initialization will pick up the pieces. */
 366                 return;
 367         }
 368         i = rp->rtort_pipe_count;
 369         if (i > RCU_TORTURE_PIPE_LEN)
 370                 i = RCU_TORTURE_PIPE_LEN;
 371         atomic_inc(&rcu_torture_wcount[i]);
 372         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 373                 rp->rtort_mbtest = 0;
 374                 rcu_torture_free(rp);
 375         } else
 376                 cur_ops->deferred_free(rp);
 377 }
 378
 379 static int rcu_no_completed(void)
 380 {
 381         return 0;
 382 }
 383
 384 static void rcu_torture_deferred_free(struct rcu_torture *p)
 385 {
 386         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 387 }
 388
 389 static struct rcu_torture_ops rcu_ops = {
 390         .init           = NULL,
 391         .cleanup        = NULL,
 392         .readlock       = rcu_torture_read_lock,
 393         .read_delay     = rcu_read_delay,
 394         .readunlock     = rcu_torture_read_unlock,
 395         .completed      = rcu_torture_completed,
 396         .deferred_free  = rcu_torture_deferred_free,
 397         .sync           = synchronize_rcu,
 398         .cb_barrier     = rcu_barrier,
 399         .fqs            = rcu_force_quiescent_state,
 400         .stats          = NULL,
 401         .irq_capable    = 1,
 402         .can_boost      = rcu_can_boost(),
 403         .name           = "rcu"
 404 };
 405
 406 static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
 407 {
 408         int i;
 409         struct rcu_torture *rp;
 410         struct rcu_torture *rp1;
 411
 412         cur_ops->sync();
 413         list_add(&p->rtort_free, &rcu_torture_removed);
 414         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 415                 i = rp->rtort_pipe_count;
 416                 if (i > RCU_TORTURE_PIPE_LEN)
 417                         i = RCU_TORTURE_PIPE_LEN;
 418                 atomic_inc(&rcu_torture_wcount[i]);
 419                 if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 420                         rp->rtort_mbtest = 0;
 421                         list_del(&rp->rtort_free);
 422                         rcu_torture_free(rp);
 423                 }
 424         }
 425 }
 426
 427 static void rcu_sync_torture_init(void)
 428 {
 429         INIT_LIST_HEAD(&rcu_torture_removed);
 430 }
 431
 432 static struct rcu_torture_ops rcu_sync_ops = {
 433         .init           = rcu_sync_torture_init,
 434         .cleanup        = NULL,
 435         .readlock       = rcu_torture_read_lock,
 436         .read_delay     = rcu_read_delay,
 437         .readunlock     = rcu_torture_read_unlock,
 438         .completed      = rcu_torture_completed,
 439         .deferred_free  = rcu_sync_torture_deferred_free,
 440         .sync           = synchronize_rcu,
 441         .cb_barrier     = NULL,
 442         .fqs            = rcu_force_quiescent_state,
 443         .stats          = NULL,
 444         .irq_capable    = 1,
 445         .can_boost      = rcu_can_boost(),
 446         .name           = "rcu_sync"
 447 };
 448
 449 static struct rcu_torture_ops rcu_expedited_ops = {
 450         .init           = rcu_sync_torture_init,
 451         .cleanup        = NULL,
 452         .readlock       = rcu_torture_read_lock,
 453         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 454         .readunlock     = rcu_torture_read_unlock,
 455         .completed      = rcu_no_completed,
 456         .deferred_free  = rcu_sync_torture_deferred_free,
 457         .sync           = synchronize_rcu_expedited,
 458         .cb_barrier     = NULL,
 459         .fqs            = rcu_force_quiescent_state,
 460         .stats          = NULL,
 461         .irq_capable    = 1,
 462         .can_boost      = rcu_can_boost(),
 463         .name           = "rcu_expedited"
 464 };
 465
 466 /*
 467  * Definitions for rcu_bh torture testing.
 468  */
 469
 470 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
 471 {
 472         rcu_read_lock_bh();
 473         return 0;
 474 }
 475
 476 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
 477 {
 478         rcu_read_unlock_bh();
 479 }
 480
 481 static int rcu_bh_torture_completed(void)
 482 {
 483         return rcu_batches_completed_bh();
 484 }
 485
 486 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 487 {
 488         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
 489 }
 490
 491 static struct rcu_torture_ops rcu_bh_ops = {
 492         .init           = NULL,
 493         .cleanup        = NULL,
 494         .readlock       = rcu_bh_torture_read_lock,
 495         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 496         .readunlock     = rcu_bh_torture_read_unlock,
 497         .completed      = rcu_bh_torture_completed,
 498         .deferred_free  = rcu_bh_torture_deferred_free,
 499         .sync           = synchronize_rcu_bh,
 500         .cb_barrier     = rcu_barrier_bh,
 501         .fqs            = rcu_bh_force_quiescent_state,
 502         .stats          = NULL,
 503         .irq_capable    = 1,
 504         .name           = "rcu_bh"
 505 };
 506
 507 static struct rcu_torture_ops rcu_bh_sync_ops = {
 508         .init           = rcu_sync_torture_init,
 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_sync_torture_deferred_free,
 515         .sync           = synchronize_rcu_bh,
 516         .cb_barrier     = NULL,
 517         .fqs            = rcu_bh_force_quiescent_state,
 518         .stats          = NULL,
 519         .irq_capable    = 1,
 520         .name           = "rcu_bh_sync"
 521 };
 522
 523 static struct rcu_torture_ops rcu_bh_expedited_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           = synchronize_rcu_bh_expedited,
 532         .cb_barrier     = NULL,
 533         .fqs            = rcu_bh_force_quiescent_state,
 534         .stats          = NULL,
 535         .irq_capable    = 1,
 536         .name           = "rcu_bh_expedited"
 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 struct rcu_torture_ops sched_ops = {
 663         .init           = rcu_sync_torture_init,
 664         .cleanup        = NULL,
 665         .readlock       = sched_torture_read_lock,
 666         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 667         .readunlock     = sched_torture_read_unlock,
 668         .completed      = rcu_no_completed,
 669         .deferred_free  = rcu_sched_torture_deferred_free,
 670         .sync           = synchronize_sched,
 671         .cb_barrier     = rcu_barrier_sched,
 672         .fqs            = rcu_sched_force_quiescent_state,
 673         .stats          = NULL,
 674         .irq_capable    = 1,
 675         .name           = "sched"
 676 };
 677
 678 static struct rcu_torture_ops sched_sync_ops = {
 679         .init           = rcu_sync_torture_init,
 680         .cleanup        = NULL,
 681         .readlock       = sched_torture_read_lock,
 682         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 683         .readunlock     = sched_torture_read_unlock,
 684         .completed      = rcu_no_completed,
 685         .deferred_free  = rcu_sync_torture_deferred_free,
 686         .sync           = synchronize_sched,
 687         .cb_barrier     = NULL,
 688         .fqs            = rcu_sched_force_quiescent_state,
 689         .stats          = NULL,
 690         .name           = "sched_sync"
 691 };
 692
 693 static struct rcu_torture_ops sched_expedited_ops = {
 694         .init           = rcu_sync_torture_init,
 695         .cleanup        = NULL,
 696         .readlock       = sched_torture_read_lock,
 697         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 698         .readunlock     = sched_torture_read_unlock,
 699         .completed      = rcu_no_completed,
 700         .deferred_free  = rcu_sync_torture_deferred_free,
 701         .sync           = synchronize_sched_expedited,
 702         .cb_barrier     = NULL,
 703         .fqs            = rcu_sched_force_quiescent_state,
 704         .stats          = NULL,
 705         .irq_capable    = 1,
 706         .name           = "sched_expedited"
 707 };
 708
 709 /*
 710  * RCU torture priority-boost testing.  Runs one real-time thread per
 711  * CPU for moderate bursts, repeatedly registering RCU callbacks and
 712  * spinning waiting for them to be invoked.  If a given callback takes
 713  * too long to be invoked, we assume that priority inversion has occurred.
 714  */
 715
 716 struct rcu_boost_inflight {
 717         struct rcu_head rcu;
 718         int inflight;
 719 };
 720
 721 static void rcu_torture_boost_cb(struct rcu_head *head)
 722 {
 723         struct rcu_boost_inflight *rbip =
 724                 container_of(head, struct rcu_boost_inflight, rcu);
 725
 726         smp_mb(); /* Ensure RCU-core accesses precede clearing ->inflight */
 727         rbip->inflight = 0;
 728 }
 729
 730 static int rcu_torture_boost(void *arg)
 731 {
 732         unsigned long call_rcu_time;
 733         unsigned long endtime;
 734         unsigned long oldstarttime;
 735         struct rcu_boost_inflight rbi = { .inflight = 0 };
 736         struct sched_param sp;
 737
 738         VERBOSE_PRINTK_STRING("rcu_torture_boost started");
 739
 740         /* Set real-time priority. */
 741         sp.sched_priority = 1;
 742         if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 743                 VERBOSE_PRINTK_STRING("rcu_torture_boost RT prio failed!");
 744                 n_rcu_torture_boost_rterror++;
 745         }
 746
 747         init_rcu_head_on_stack(&rbi.rcu);
 748         /* Each pass through the following loop does one boost-test cycle. */
 749         do {
 750                 /* Wait for the next test interval. */
 751                 oldstarttime = boost_starttime;
 752                 while (ULONG_CMP_LT(jiffies, oldstarttime)) {
 753                         schedule_timeout_uninterruptible(1);
 754                         rcu_stutter_wait("rcu_torture_boost");
 755                         if (kthread_should_stop() ||
 756                             fullstop != FULLSTOP_DONTSTOP)
 757                                 goto checkwait;
 758                 }
 759
 760                 /* Do one boost-test interval. */
 761                 endtime = oldstarttime + test_boost_duration * HZ;
 762                 call_rcu_time = jiffies;
 763                 while (ULONG_CMP_LT(jiffies, endtime)) {
 764                         /* If we don't have a callback in flight, post one. */
 765                         if (!rbi.inflight) {
 766                                 smp_mb(); /* RCU core before ->inflight = 1. */
 767                                 rbi.inflight = 1;
 768                                 call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 769                                 if (jiffies - call_rcu_time >
 770                                          test_boost_duration * HZ - HZ / 2) {
 771                                         VERBOSE_PRINTK_STRING("rcu_torture_boost boosting failed");
 772                                         n_rcu_torture_boost_failure++;
 773                                 }
 774                                 call_rcu_time = jiffies;
 775                         }
 776                         cond_resched();
 777                         rcu_stutter_wait("rcu_torture_boost");
 778                         if (kthread_should_stop() ||
 779                             fullstop != FULLSTOP_DONTSTOP)
 780                                 goto checkwait;
 781                 }
 782
 783                 /*
 784                  * Set the start time of the next test interval.
 785                  * Yes, this is vulnerable to long delays, but such
 786                  * delays simply cause a false negative for the next
 787                  * interval.  Besides, we are running at RT priority,
 788                  * so delays should be relatively rare.
 789                  */
 790                 while (oldstarttime == boost_starttime &&
 791                        !kthread_should_stop()) {
 792                         if (mutex_trylock(&boost_mutex)) {
 793                                 boost_starttime = jiffies +
 794                                                   test_boost_interval * HZ;
 795                                 n_rcu_torture_boosts++;
 796                                 mutex_unlock(&boost_mutex);
 797                                 break;
 798                         }
 799                         schedule_timeout_uninterruptible(1);
 800                 }
 801
 802                 /* Go do the stutter. */
 803 checkwait:      rcu_stutter_wait("rcu_torture_boost");
 804         } while (!kthread_should_stop() && fullstop  == FULLSTOP_DONTSTOP);
 805
 806         /* Clean up and exit. */
 807         VERBOSE_PRINTK_STRING("rcu_torture_boost task stopping");
 808         rcutorture_shutdown_absorb("rcu_torture_boost");
 809         while (!kthread_should_stop() || rbi.inflight)
 810                 schedule_timeout_uninterruptible(1);
 811         smp_mb(); /* order accesses to ->inflight before stack-frame death. */
 812         destroy_rcu_head_on_stack(&rbi.rcu);
 813         return 0;
 814 }
 815
 816 /*
 817  * RCU torture force-quiescent-state kthread.  Repeatedly induces
 818  * bursts of calls to force_quiescent_state(), increasing the probability
 819  * of occurrence of some important types of race conditions.
 820  */
 821 static int
 822 rcu_torture_fqs(void *arg)
 823 {
 824         unsigned long fqs_resume_time;
 825         int fqs_burst_remaining;
 826
 827         VERBOSE_PRINTK_STRING("rcu_torture_fqs task started");
 828         do {
 829                 fqs_resume_time = jiffies + fqs_stutter * HZ;
 830                 while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
 831                        !kthread_should_stop()) {
 832                         schedule_timeout_interruptible(1);
 833                 }
 834                 fqs_burst_remaining = fqs_duration;
 835                 while (fqs_burst_remaining > 0 &&
 836                        !kthread_should_stop()) {
 837                         cur_ops->fqs();
 838                         udelay(fqs_holdoff);
 839                         fqs_burst_remaining -= fqs_holdoff;
 840                 }
 841                 rcu_stutter_wait("rcu_torture_fqs");
 842         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 843         VERBOSE_PRINTK_STRING("rcu_torture_fqs task stopping");
 844         rcutorture_shutdown_absorb("rcu_torture_fqs");
 845         while (!kthread_should_stop())
 846                 schedule_timeout_uninterruptible(1);
 847         return 0;
 848 }
 849
 850 /*
 851  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 852  * for that pointed to by rcu_torture_current, freeing the old structure
 853  * after a series of grace periods (the "pipeline").
 854  */
 855 static int
 856 rcu_torture_writer(void *arg)
 857 {
 858         int i;
 859         long oldbatch = rcu_batches_completed();
 860         struct rcu_torture *rp;
 861         struct rcu_torture *old_rp;
 862         static DEFINE_RCU_RANDOM(rand);
 863
 864         VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
 865         set_user_nice(current, 19);
 866
 867         do {
 868                 schedule_timeout_uninterruptible(1);
 869                 rp = rcu_torture_alloc();
 870                 if (rp == NULL)
 871                         continue;
 872                 rp->rtort_pipe_count = 0;
 873                 udelay(rcu_random(&rand) & 0x3ff);
 874                 old_rp = rcu_dereference_check(rcu_torture_current,
 875                                                current == writer_task);
 876                 rp->rtort_mbtest = 1;
 877                 rcu_assign_pointer(rcu_torture_current, rp);
 878                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
 879                 if (old_rp) {
 880                         i = old_rp->rtort_pipe_count;
 881                         if (i > RCU_TORTURE_PIPE_LEN)
 882                                 i = RCU_TORTURE_PIPE_LEN;
 883                         atomic_inc(&rcu_torture_wcount[i]);
 884                         old_rp->rtort_pipe_count++;
 885                         cur_ops->deferred_free(old_rp);
 886                 }
 887                 rcutorture_record_progress(++rcu_torture_current_version);
 888                 oldbatch = cur_ops->completed();
 889                 rcu_stutter_wait("rcu_torture_writer");
 890         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 891         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
 892         rcutorture_shutdown_absorb("rcu_torture_writer");
 893         while (!kthread_should_stop())
 894                 schedule_timeout_uninterruptible(1);
 895         return 0;
 896 }
 897
 898 /*
 899  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
 900  * delay between calls.
 901  */
 902 static int
 903 rcu_torture_fakewriter(void *arg)
 904 {
 905         DEFINE_RCU_RANDOM(rand);
 906
 907         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
 908         set_user_nice(current, 19);
 909
 910         do {
 911                 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
 912                 udelay(rcu_random(&rand) & 0x3ff);
 913                 cur_ops->sync();
 914                 rcu_stutter_wait("rcu_torture_fakewriter");
 915         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 916
 917         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
 918         rcutorture_shutdown_absorb("rcu_torture_fakewriter");
 919         while (!kthread_should_stop())
 920                 schedule_timeout_uninterruptible(1);
 921         return 0;
 922 }
 923
 924 void rcutorture_trace_dump(void)
 925 {
 926         static atomic_t beenhere = ATOMIC_INIT(0);
 927
 928         if (atomic_read(&beenhere))
 929                 return;
 930         if (atomic_xchg(&beenhere, 1) != 0)
 931                 return;
 932         do_trace_rcu_torture_read(cur_ops->name, (struct rcu_head *)~0UL);
 933         ftrace_dump(DUMP_ALL);
 934 }
 935
 936 /*
 937  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
 938  * incrementing the corresponding element of the pipeline array.  The
 939  * counter in the element should never be greater than 1, otherwise, the
 940  * RCU implementation is broken.
 941  */
 942 static void rcu_torture_timer(unsigned long unused)
 943 {
 944         int idx;
 945         int completed;
 946         static DEFINE_RCU_RANDOM(rand);
 947         static DEFINE_SPINLOCK(rand_lock);
 948         struct rcu_torture *p;
 949         int pipe_count;
 950
 951         idx = cur_ops->readlock();
 952         completed = cur_ops->completed();
 953         p = rcu_dereference_check(rcu_torture_current,
 954                                   rcu_read_lock_bh_held() ||
 955                                   rcu_read_lock_sched_held() ||
 956                                   srcu_read_lock_held(&srcu_ctl));
 957         do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu);
 958         if (p == NULL) {
 959                 /* Leave because rcu_torture_writer is not yet underway */
 960                 cur_ops->readunlock(idx);
 961                 return;
 962         }
 963         if (p->rtort_mbtest == 0)
 964                 atomic_inc(&n_rcu_torture_mberror);
 965         spin_lock(&rand_lock);
 966         cur_ops->read_delay(&rand);
 967         n_rcu_torture_timers++;
 968         spin_unlock(&rand_lock);
 969         preempt_disable();
 970         pipe_count = p->rtort_pipe_count;
 971         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
 972                 /* Should not happen, but... */
 973                 pipe_count = RCU_TORTURE_PIPE_LEN;
 974         }
 975         if (pipe_count > 1)
 976                 rcutorture_trace_dump();
 977         __this_cpu_inc(rcu_torture_count[pipe_count]);
 978         completed = cur_ops->completed() - completed;
 979         if (completed > RCU_TORTURE_PIPE_LEN) {
 980                 /* Should not happen, but... */
 981                 completed = RCU_TORTURE_PIPE_LEN;
 982         }
 983         __this_cpu_inc(rcu_torture_batch[completed]);
 984         preempt_enable();
 985         cur_ops->readunlock(idx);
 986 }
 987
 988 /*
 989  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
 990  * incrementing the corresponding element of the pipeline array.  The
 991  * counter in the element should never be greater than 1, otherwise, the
 992  * RCU implementation is broken.
 993  */
 994 static int
 995 rcu_torture_reader(void *arg)
 996 {
 997         int completed;
 998         int idx;
 999         DEFINE_RCU_RANDOM(rand);
1000         struct rcu_torture *p;
1001         int pipe_count;
1002         struct timer_list t;
1003
1004         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
1005         set_user_nice(current, 19);
1006         if (irqreader && cur_ops->irq_capable)
1007                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
1008
1009         do {
1010                 if (irqreader && cur_ops->irq_capable) {
1011                         if (!timer_pending(&t))
1012                                 mod_timer(&t, jiffies + 1);
1013                 }
1014                 idx = cur_ops->readlock();
1015                 completed = cur_ops->completed();
1016                 p = rcu_dereference_check(rcu_torture_current,
1017                                           rcu_read_lock_bh_held() ||
1018                                           rcu_read_lock_sched_held() ||
1019                                           srcu_read_lock_held(&srcu_ctl));
1020                 do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu);
1021                 if (p == NULL) {
1022                         /* Wait for rcu_torture_writer to get underway */
1023                         cur_ops->readunlock(idx);
1024                         schedule_timeout_interruptible(HZ);
1025                         continue;
1026                 }
1027                 if (p->rtort_mbtest == 0)
1028                         atomic_inc(&n_rcu_torture_mberror);
1029                 cur_ops->read_delay(&rand);
1030                 preempt_disable();
1031                 pipe_count = p->rtort_pipe_count;
1032                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1033                         /* Should not happen, but... */
1034                         pipe_count = RCU_TORTURE_PIPE_LEN;
1035                 }
1036                 if (pipe_count > 1)
1037                         rcutorture_trace_dump();
1038                 __this_cpu_inc(rcu_torture_count[pipe_count]);
1039                 completed = cur_ops->completed() - completed;
1040                 if (completed > RCU_TORTURE_PIPE_LEN) {
1041                         /* Should not happen, but... */
1042                         completed = RCU_TORTURE_PIPE_LEN;
1043                 }
1044                 __this_cpu_inc(rcu_torture_batch[completed]);
1045                 preempt_enable();
1046                 cur_ops->readunlock(idx);
1047                 schedule();
1048                 rcu_stutter_wait("rcu_torture_reader");
1049         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1050         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
1051         rcutorture_shutdown_absorb("rcu_torture_reader");
1052         if (irqreader && cur_ops->irq_capable)
1053                 del_timer_sync(&t);
1054         while (!kthread_should_stop())
1055                 schedule_timeout_uninterruptible(1);
1056         return 0;
1057 }
1058
1059 /*
1060  * Create an RCU-torture statistics message in the specified buffer.
1061  */
1062 static int
1063 rcu_torture_printk(char *page)
1064 {
1065         int cnt = 0;
1066         int cpu;
1067         int i;
1068         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1069         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1070
1071         for_each_possible_cpu(cpu) {
1072                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1073                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1074                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1075                 }
1076         }
1077         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1078                 if (pipesummary[i] != 0)
1079                         break;
1080         }
1081         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
1082         cnt += sprintf(&page[cnt],
1083                        "rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d "
1084                        "rtmbe: %d rtbke: %ld rtbre: %ld "
1085                        "rtbf: %ld rtb: %ld nt: %ld",
1086                        rcu_torture_current,
1087                        rcu_torture_current_version,
1088                        list_empty(&rcu_torture_freelist),
1089                        atomic_read(&n_rcu_torture_alloc),
1090                        atomic_read(&n_rcu_torture_alloc_fail),
1091                        atomic_read(&n_rcu_torture_free),
1092                        atomic_read(&n_rcu_torture_mberror),
1093                        n_rcu_torture_boost_ktrerror,
1094                        n_rcu_torture_boost_rterror,
1095                        n_rcu_torture_boost_failure,
1096                        n_rcu_torture_boosts,
1097                        n_rcu_torture_timers);
1098         if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1099             n_rcu_torture_boost_ktrerror != 0 ||
1100             n_rcu_torture_boost_rterror != 0 ||
1101             n_rcu_torture_boost_failure != 0)
1102                 cnt += sprintf(&page[cnt], " !!!");
1103         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1104         if (i > 1) {
1105                 cnt += sprintf(&page[cnt], "!!! ");
1106                 atomic_inc(&n_rcu_torture_error);
1107                 WARN_ON_ONCE(1);
1108         }
1109         cnt += sprintf(&page[cnt], "Reader Pipe: ");
1110         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1111                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
1112         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1113         cnt += sprintf(&page[cnt], "Reader Batch: ");
1114         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1115                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
1116         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1117         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
1118         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1119                 cnt += sprintf(&page[cnt], " %d",
1120                                atomic_read(&rcu_torture_wcount[i]));
1121         }
1122         cnt += sprintf(&page[cnt], "\n");
1123         if (cur_ops->stats)
1124                 cnt += cur_ops->stats(&page[cnt]);
1125         return cnt;
1126 }
1127
1128 /*
1129  * Print torture statistics.  Caller must ensure that there is only
1130  * one call to this function at a given time!!!  This is normally
1131  * accomplished by relying on the module system to only have one copy
1132  * of the module loaded, and then by giving the rcu_torture_stats
1133  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1134  * thread is not running).
1135  */
1136 static void
1137 rcu_torture_stats_print(void)
1138 {
1139         int cnt;
1140
1141         cnt = rcu_torture_printk(printk_buf);
1142         printk(KERN_ALERT "%s", printk_buf);
1143 }
1144
1145 /*
1146  * Periodically prints torture statistics, if periodic statistics printing
1147  * was specified via the stat_interval module parameter.
1148  *
1149  * No need to worry about fullstop here, since this one doesn't reference
1150  * volatile state or register callbacks.
1151  */
1152 static int
1153 rcu_torture_stats(void *arg)
1154 {
1155         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
1156         do {
1157                 schedule_timeout_interruptible(stat_interval * HZ);
1158                 rcu_torture_stats_print();
1159                 rcutorture_shutdown_absorb("rcu_torture_stats");
1160         } while (!kthread_should_stop());
1161         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
1162         return 0;
1163 }
1164
1165 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
1166
1167 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
1168  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
1169  */
1170 static void rcu_torture_shuffle_tasks(void)
1171 {
1172         int i;
1173
1174         cpumask_setall(shuffle_tmp_mask);
1175         get_online_cpus();
1176
1177         /* No point in shuffling if there is only one online CPU (ex: UP) */
1178         if (num_online_cpus() == 1) {
1179                 put_online_cpus();
1180                 return;
1181         }
1182
1183         if (rcu_idle_cpu != -1)
1184                 cpumask_clear_cpu(rcu_idle_cpu, shuffle_tmp_mask);
1185
1186         set_cpus_allowed_ptr(current, shuffle_tmp_mask);
1187
1188         if (reader_tasks) {
1189                 for (i = 0; i < nrealreaders; i++)
1190                         if (reader_tasks[i])
1191                                 set_cpus_allowed_ptr(reader_tasks[i],
1192                                                      shuffle_tmp_mask);
1193         }
1194
1195         if (fakewriter_tasks) {
1196                 for (i = 0; i < nfakewriters; i++)
1197                         if (fakewriter_tasks[i])
1198                                 set_cpus_allowed_ptr(fakewriter_tasks[i],
1199                                                      shuffle_tmp_mask);
1200         }
1201
1202         if (writer_task)
1203                 set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
1204
1205         if (stats_task)
1206                 set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
1207
1208         if (rcu_idle_cpu == -1)
1209                 rcu_idle_cpu = num_online_cpus() - 1;
1210         else
1211                 rcu_idle_cpu--;
1212
1213         put_online_cpus();
1214 }
1215
1216 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
1217  * system to become idle at a time and cut off its timer ticks. This is meant
1218  * to test the support for such tickless idle CPU in RCU.
1219  */
1220 static int
1221 rcu_torture_shuffle(void *arg)
1222 {
1223         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
1224         do {
1225                 schedule_timeout_interruptible(shuffle_interval * HZ);
1226                 rcu_torture_shuffle_tasks();
1227                 rcutorture_shutdown_absorb("rcu_torture_shuffle");
1228         } while (!kthread_should_stop());
1229         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
1230         return 0;
1231 }
1232
1233 /* Cause the rcutorture test to "stutter", starting and stopping all
1234  * threads periodically.
1235  */
1236 static int
1237 rcu_torture_stutter(void *arg)
1238 {
1239         VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
1240         do {
1241                 schedule_timeout_interruptible(stutter * HZ);
1242                 stutter_pause_test = 1;
1243                 if (!kthread_should_stop())
1244                         schedule_timeout_interruptible(stutter * HZ);
1245                 stutter_pause_test = 0;
1246                 rcutorture_shutdown_absorb("rcu_torture_stutter");
1247         } while (!kthread_should_stop());
1248         VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
1249         return 0;
1250 }
1251
1252 static inline void
1253 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, char *tag)
1254 {
1255         printk(KERN_ALERT "%s" TORTURE_FLAG
1256                 "--- %s: nreaders=%d nfakewriters=%d "
1257                 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1258                 "shuffle_interval=%d stutter=%d irqreader=%d "
1259                 "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1260                 "test_boost=%d/%d test_boost_interval=%d "
1261                 "test_boost_duration=%d shutdown_secs=%d\n",
1262                 torture_type, tag, nrealreaders, nfakewriters,
1263                 stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1264                 stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1265                 test_boost, cur_ops->can_boost,
1266                 test_boost_interval, test_boost_duration, shutdown_secs);
1267 }
1268
1269 static struct notifier_block rcutorture_shutdown_nb = {
1270         .notifier_call = rcutorture_shutdown_notify,
1271 };
1272
1273 static void rcutorture_booster_cleanup(int cpu)
1274 {
1275         struct task_struct *t;
1276
1277         if (boost_tasks[cpu] == NULL)
1278                 return;
1279         mutex_lock(&boost_mutex);
1280         VERBOSE_PRINTK_STRING("Stopping rcu_torture_boost task");
1281         t = boost_tasks[cpu];
1282         boost_tasks[cpu] = NULL;
1283         mutex_unlock(&boost_mutex);
1284
1285         /* This must be outside of the mutex, otherwise deadlock! */
1286         kthread_stop(t);
1287 }
1288
1289 static int rcutorture_booster_init(int cpu)
1290 {
1291         int retval;
1292
1293         if (boost_tasks[cpu] != NULL)
1294                 return 0;  /* Already created, nothing more to do. */
1295
1296         /* Don't allow time recalculation while creating a new task. */
1297         mutex_lock(&boost_mutex);
1298         VERBOSE_PRINTK_STRING("Creating rcu_torture_boost task");
1299         boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1300                                                   cpu_to_node(cpu),
1301                                                   "rcu_torture_boost");
1302         if (IS_ERR(boost_tasks[cpu])) {
1303                 retval = PTR_ERR(boost_tasks[cpu]);
1304                 VERBOSE_PRINTK_STRING("rcu_torture_boost task create failed");
1305                 n_rcu_torture_boost_ktrerror++;
1306                 boost_tasks[cpu] = NULL;
1307                 mutex_unlock(&boost_mutex);
1308                 return retval;
1309         }
1310         kthread_bind(boost_tasks[cpu], cpu);
1311         wake_up_process(boost_tasks[cpu]);
1312         mutex_unlock(&boost_mutex);
1313         return 0;
1314 }
1315
1316 /*
1317  * Cause the rcutorture test to shutdown the system after the test has
1318  * run for the time specified by the shutdown_secs module parameter.
1319  */
1320 static int
1321 rcu_torture_shutdown(void *arg)
1322 {
1323         long delta;
1324         unsigned long jiffies_snap;
1325
1326         VERBOSE_PRINTK_STRING("rcu_torture_shutdown task started");
1327         jiffies_snap = ACCESS_ONCE(jiffies);
1328         while (ULONG_CMP_LT(jiffies_snap, shutdown_time) &&
1329                !kthread_should_stop()) {
1330                 delta = shutdown_time - jiffies_snap;
1331                 if (verbose)
1332                         printk(KERN_ALERT "%s" TORTURE_FLAG
1333                                "rcu_torture_shutdown task: %lu "
1334                                "jiffies remaining\n",
1335                                torture_type, delta);
1336                 schedule_timeout_interruptible(delta);
1337                 jiffies_snap = ACCESS_ONCE(jiffies);
1338         }
1339         if (ULONG_CMP_LT(jiffies, shutdown_time)) {
1340                 VERBOSE_PRINTK_STRING("rcu_torture_shutdown task stopping");
1341                 return 0;
1342         }
1343
1344         /* OK, shut down the system. */
1345
1346         VERBOSE_PRINTK_STRING("rcu_torture_shutdown task shutting down system");
1347         shutdown_task = NULL;   /* Avoid self-kill deadlock. */
1348         rcu_torture_cleanup();  /* Get the success/failure message. */
1349         kernel_power_off();     /* Shut down the system. */
1350         return 0;
1351 }
1352
1353 static int rcutorture_cpu_notify(struct notifier_block *self,
1354                                  unsigned long action, void *hcpu)
1355 {
1356         long cpu = (long)hcpu;
1357
1358         switch (action) {
1359         case CPU_ONLINE:
1360         case CPU_DOWN_FAILED:
1361                 (void)rcutorture_booster_init(cpu);
1362                 break;
1363         case CPU_DOWN_PREPARE:
1364                 rcutorture_booster_cleanup(cpu);
1365                 break;
1366         default:
1367                 break;
1368         }
1369         return NOTIFY_OK;
1370 }
1371
1372 static struct notifier_block rcutorture_cpu_nb = {
1373         .notifier_call = rcutorture_cpu_notify,
1374 };
1375
1376 static void
1377 rcu_torture_cleanup(void)
1378 {
1379         int i;
1380
1381         mutex_lock(&fullstop_mutex);
1382         rcutorture_record_test_transition();
1383         if (fullstop == FULLSTOP_SHUTDOWN) {
1384                 printk(KERN_WARNING /* but going down anyway, so... */
1385                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
1386                 mutex_unlock(&fullstop_mutex);
1387                 schedule_timeout_uninterruptible(10);
1388                 if (cur_ops->cb_barrier != NULL)
1389                         cur_ops->cb_barrier();
1390                 return;
1391         }
1392         fullstop = FULLSTOP_RMMOD;
1393         mutex_unlock(&fullstop_mutex);
1394         unregister_reboot_notifier(&rcutorture_shutdown_nb);
1395         if (stutter_task) {
1396                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
1397                 kthread_stop(stutter_task);
1398         }
1399         stutter_task = NULL;
1400         if (shuffler_task) {
1401                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
1402                 kthread_stop(shuffler_task);
1403                 free_cpumask_var(shuffle_tmp_mask);
1404         }
1405         shuffler_task = NULL;
1406
1407         if (writer_task) {
1408                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
1409                 kthread_stop(writer_task);
1410         }
1411         writer_task = NULL;
1412
1413         if (reader_tasks) {
1414                 for (i = 0; i < nrealreaders; i++) {
1415                         if (reader_tasks[i]) {
1416                                 VERBOSE_PRINTK_STRING(
1417                                         "Stopping rcu_torture_reader task");
1418                                 kthread_stop(reader_tasks[i]);
1419                         }
1420                         reader_tasks[i] = NULL;
1421                 }
1422                 kfree(reader_tasks);
1423                 reader_tasks = NULL;
1424         }
1425         rcu_torture_current = NULL;
1426
1427         if (fakewriter_tasks) {
1428                 for (i = 0; i < nfakewriters; i++) {
1429                         if (fakewriter_tasks[i]) {
1430                                 VERBOSE_PRINTK_STRING(
1431                                         "Stopping rcu_torture_fakewriter task");
1432                                 kthread_stop(fakewriter_tasks[i]);
1433                         }
1434                         fakewriter_tasks[i] = NULL;
1435                 }
1436                 kfree(fakewriter_tasks);
1437                 fakewriter_tasks = NULL;
1438         }
1439
1440         if (stats_task) {
1441                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
1442                 kthread_stop(stats_task);
1443         }
1444         stats_task = NULL;
1445
1446         if (fqs_task) {
1447                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_fqs task");
1448                 kthread_stop(fqs_task);
1449         }
1450         fqs_task = NULL;
1451         if ((test_boost == 1 && cur_ops->can_boost) ||
1452             test_boost == 2) {
1453                 unregister_cpu_notifier(&rcutorture_cpu_nb);
1454                 for_each_possible_cpu(i)
1455                         rcutorture_booster_cleanup(i);
1456         }
1457         if (shutdown_task != NULL) {
1458                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shutdown task");
1459                 kthread_stop(shutdown_task);
1460         }
1461
1462         /* Wait for all RCU callbacks to fire.  */
1463
1464         if (cur_ops->cb_barrier != NULL)
1465                 cur_ops->cb_barrier();
1466
1467         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1468
1469         if (cur_ops->cleanup)
1470                 cur_ops->cleanup();
1471         if (atomic_read(&n_rcu_torture_error))
1472                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1473         else
1474                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1475 }
1476
1477 static int __init
1478 rcu_torture_init(void)
1479 {
1480         int i;
1481         int cpu;
1482         int firsterr = 0;
1483         static struct rcu_torture_ops *torture_ops[] =
1484                 { &rcu_ops, &rcu_sync_ops, &rcu_expedited_ops,
1485                   &rcu_bh_ops, &rcu_bh_sync_ops, &rcu_bh_expedited_ops,
1486                   &srcu_ops, &srcu_expedited_ops,
1487                   &sched_ops, &sched_sync_ops, &sched_expedited_ops, };
1488
1489         mutex_lock(&fullstop_mutex);
1490
1491         /* Process args and tell the world that the torturer is on the job. */
1492         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1493                 cur_ops = torture_ops[i];
1494                 if (strcmp(torture_type, cur_ops->name) == 0)
1495                         break;
1496         }
1497         if (i == ARRAY_SIZE(torture_ops)) {
1498                 printk(KERN_ALERT "rcu-torture: invalid torture type: \"%s\"\n",
1499                        torture_type);
1500                 printk(KERN_ALERT "rcu-torture types:");
1501                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1502                         printk(KERN_ALERT " %s", torture_ops[i]->name);
1503                 printk(KERN_ALERT "\n");
1504                 mutex_unlock(&fullstop_mutex);
1505                 return -EINVAL;
1506         }
1507         if (cur_ops->fqs == NULL && fqs_duration != 0) {
1508                 printk(KERN_ALERT "rcu-torture: ->fqs NULL and non-zero "
1509                                   "fqs_duration, fqs disabled.\n");
1510                 fqs_duration = 0;
1511         }
1512         if (cur_ops->init)
1513                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1514
1515         if (nreaders >= 0)
1516                 nrealreaders = nreaders;
1517         else
1518                 nrealreaders = 2 * num_online_cpus();
1519         rcu_torture_print_module_parms(cur_ops, "Start of test");
1520         fullstop = FULLSTOP_DONTSTOP;
1521
1522         /* Set up the freelist. */
1523
1524         INIT_LIST_HEAD(&rcu_torture_freelist);
1525         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1526                 rcu_tortures[i].rtort_mbtest = 0;
1527                 list_add_tail(&rcu_tortures[i].rtort_free,
1528                               &rcu_torture_freelist);
1529         }
1530
1531         /* Initialize the statistics so that each run gets its own numbers. */
1532
1533         rcu_torture_current = NULL;
1534         rcu_torture_current_version = 0;
1535         atomic_set(&n_rcu_torture_alloc, 0);
1536         atomic_set(&n_rcu_torture_alloc_fail, 0);
1537         atomic_set(&n_rcu_torture_free, 0);
1538         atomic_set(&n_rcu_torture_mberror, 0);
1539         atomic_set(&n_rcu_torture_error, 0);
1540         n_rcu_torture_boost_ktrerror = 0;
1541         n_rcu_torture_boost_rterror = 0;
1542         n_rcu_torture_boost_failure = 0;
1543         n_rcu_torture_boosts = 0;
1544         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1545                 atomic_set(&rcu_torture_wcount[i], 0);
1546         for_each_possible_cpu(cpu) {
1547                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1548                         per_cpu(rcu_torture_count, cpu)[i] = 0;
1549                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
1550                 }
1551         }
1552
1553         /* Start up the kthreads. */
1554
1555         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
1556         writer_task = kthread_run(rcu_torture_writer, NULL,
1557                                   "rcu_torture_writer");
1558         if (IS_ERR(writer_task)) {
1559                 firsterr = PTR_ERR(writer_task);
1560                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
1561                 writer_task = NULL;
1562                 goto unwind;
1563         }
1564         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1565                                    GFP_KERNEL);
1566         if (fakewriter_tasks == NULL) {
1567                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1568                 firsterr = -ENOMEM;
1569                 goto unwind;
1570         }
1571         for (i = 0; i < nfakewriters; i++) {
1572                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
1573                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
1574                                                   "rcu_torture_fakewriter");
1575                 if (IS_ERR(fakewriter_tasks[i])) {
1576                         firsterr = PTR_ERR(fakewriter_tasks[i]);
1577                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
1578                         fakewriter_tasks[i] = NULL;
1579                         goto unwind;
1580                 }
1581         }
1582         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1583                                GFP_KERNEL);
1584         if (reader_tasks == NULL) {
1585                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1586                 firsterr = -ENOMEM;
1587                 goto unwind;
1588         }
1589         for (i = 0; i < nrealreaders; i++) {
1590                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
1591                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
1592                                               "rcu_torture_reader");
1593                 if (IS_ERR(reader_tasks[i])) {
1594                         firsterr = PTR_ERR(reader_tasks[i]);
1595                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
1596                         reader_tasks[i] = NULL;
1597                         goto unwind;
1598                 }
1599         }
1600         if (stat_interval > 0) {
1601                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
1602                 stats_task = kthread_run(rcu_torture_stats, NULL,
1603                                         "rcu_torture_stats");
1604                 if (IS_ERR(stats_task)) {
1605                         firsterr = PTR_ERR(stats_task);
1606                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
1607                         stats_task = NULL;
1608                         goto unwind;
1609                 }
1610         }
1611         if (test_no_idle_hz) {
1612                 rcu_idle_cpu = num_online_cpus() - 1;
1613
1614                 if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
1615                         firsterr = -ENOMEM;
1616                         VERBOSE_PRINTK_ERRSTRING("Failed to alloc mask");
1617                         goto unwind;
1618                 }
1619
1620                 /* Create the shuffler thread */
1621                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
1622                                           "rcu_torture_shuffle");
1623                 if (IS_ERR(shuffler_task)) {
1624                         free_cpumask_var(shuffle_tmp_mask);
1625                         firsterr = PTR_ERR(shuffler_task);
1626                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
1627                         shuffler_task = NULL;
1628                         goto unwind;
1629                 }
1630         }
1631         if (stutter < 0)
1632                 stutter = 0;
1633         if (stutter) {
1634                 /* Create the stutter thread */
1635                 stutter_task = kthread_run(rcu_torture_stutter, NULL,
1636                                           "rcu_torture_stutter");
1637                 if (IS_ERR(stutter_task)) {
1638                         firsterr = PTR_ERR(stutter_task);
1639                         VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
1640                         stutter_task = NULL;
1641                         goto unwind;
1642                 }
1643         }
1644         if (fqs_duration < 0)
1645                 fqs_duration = 0;
1646         if (fqs_duration) {
1647                 /* Create the stutter thread */
1648                 fqs_task = kthread_run(rcu_torture_fqs, NULL,
1649                                        "rcu_torture_fqs");
1650                 if (IS_ERR(fqs_task)) {
1651                         firsterr = PTR_ERR(fqs_task);
1652                         VERBOSE_PRINTK_ERRSTRING("Failed to create fqs");
1653                         fqs_task = NULL;
1654                         goto unwind;
1655                 }
1656         }
1657         if (test_boost_interval < 1)
1658                 test_boost_interval = 1;
1659         if (test_boost_duration < 2)
1660                 test_boost_duration = 2;
1661         if ((test_boost == 1 && cur_ops->can_boost) ||
1662             test_boost == 2) {
1663                 int retval;
1664
1665                 boost_starttime = jiffies + test_boost_interval * HZ;
1666                 register_cpu_notifier(&rcutorture_cpu_nb);
1667                 for_each_possible_cpu(i) {
1668                         if (cpu_is_offline(i))
1669                                 continue;  /* Heuristic: CPU can go offline. */
1670                         retval = rcutorture_booster_init(i);
1671                         if (retval < 0) {
1672                                 firsterr = retval;
1673                                 goto unwind;
1674                         }
1675                 }
1676         }
1677         if (shutdown_secs > 0) {
1678                 shutdown_time = jiffies + shutdown_secs * HZ;
1679                 shutdown_task = kthread_run(rcu_torture_shutdown, NULL,
1680                                             "rcu_torture_shutdown");
1681                 if (IS_ERR(shutdown_task)) {
1682                         firsterr = PTR_ERR(shutdown_task);
1683                         VERBOSE_PRINTK_ERRSTRING("Failed to create shutdown");
1684                         shutdown_task = NULL;
1685                         goto unwind;
1686                 }
1687         }
1688         register_reboot_notifier(&rcutorture_shutdown_nb);
1689         rcutorture_record_test_transition();
1690         mutex_unlock(&fullstop_mutex);
1691         return 0;
1692
1693 unwind:
1694         mutex_unlock(&fullstop_mutex);
1695         rcu_torture_cleanup();
1696         return firsterr;
1697 }
1698
1699 module_init(rcu_torture_init);
1700 module_exit(rcu_torture_cleanup);