kernel/rcutorture.c

   1 /*
   2  * Read-Copy Update module-based torture test facility
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  17  *
  18  * Copyright (C) IBM Corporation, 2005, 2006
  19  *
  20  * Authors: Paul E. McKenney <paulmck@us.ibm.com>
  21  *        Josh Triplett <josh@freedesktop.org>
  22  *
  23  * See also:  Documentation/RCU/torture.txt
  24  */
  25 #include <linux/types.h>
  26 #include <linux/kernel.h>
  27 #include <linux/init.h>
  28 #include <linux/module.h>
  29 #include <linux/kthread.h>
  30 #include <linux/err.h>
  31 #include <linux/spinlock.h>
  32 #include <linux/smp.h>
  33 #include <linux/rcupdate.h>
  34 #include <linux/interrupt.h>
  35 #include <linux/sched.h>
  36 #include <linux/atomic.h>
  37 #include <linux/bitops.h>
  38 #include <linux/completion.h>
  39 #include <linux/moduleparam.h>
  40 #include <linux/percpu.h>
  41 #include <linux/notifier.h>
  42 #include <linux/reboot.h>
  43 #include <linux/freezer.h>
  44 #include <linux/cpu.h>
  45 #include <linux/delay.h>
  46 #include <linux/stat.h>
  47 #include <linux/srcu.h>
  48 #include <linux/slab.h>
  49 #include <asm/byteorder.h>
  50
  51 MODULE_LICENSE("GPL");
  52 MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and Josh Triplett <josh@freedesktop.org>");
  53
  54 static int nreaders = -1;       /* # reader threads, defaults to 2*ncpus */
  55 static int nfakewriters = 4;    /* # fake writer threads */
  56 static int stat_interval = 60;  /* Interval between stats, in seconds. */
  57                                 /*  Zero means "only at end of test". */
  58 static bool verbose;            /* Print more debug info. */
  59 static bool test_no_idle_hz = true;
  60                                 /* Test RCU 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 n_barrier_cbs;       /* Number of callbacks to test RCU barriers. */
  68 static int onoff_interval;      /* Wait time between CPU hotplugs, 0=disable. */
  69 static int onoff_holdoff;       /* Seconds after boot before CPU hotplugs. */
  70 static int shutdown_secs;       /* Shutdown time (s).  <=0 for no shutdown. */
  71 static int stall_cpu;           /* CPU-stall duration (s).  0 for no stall. */
  72 static int stall_cpu_holdoff = 10; /* Time to wait until stall (s).  */
  73 static int test_boost = 1;      /* Test RCU prio boost: 0=no, 1=maybe, 2=yes. */
  74 static int test_boost_interval = 7; /* Interval between boost tests, seconds. */
  75 static int test_boost_duration = 4; /* Duration of each boost test, seconds. */
  76 static char *torture_type = "rcu"; /* What RCU implementation to torture. */
  77
  78 module_param(nreaders, int, 0444);
  79 MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
  80 module_param(nfakewriters, int, 0444);
  81 MODULE_PARM_DESC(nfakewriters, "Number of RCU fake writer threads");
  82 module_param(stat_interval, int, 0644);
  83 MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
  84 module_param(verbose, bool, 0444);
  85 MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
  86 module_param(test_no_idle_hz, bool, 0444);
  87 MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
  88 module_param(shuffle_interval, int, 0444);
  89 MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
  90 module_param(stutter, int, 0444);
  91 MODULE_PARM_DESC(stutter, "Number of seconds to run/halt test");
  92 module_param(irqreader, int, 0444);
  93 MODULE_PARM_DESC(irqreader, "Allow RCU readers from irq handlers");
  94 module_param(fqs_duration, int, 0444);
  95 MODULE_PARM_DESC(fqs_duration, "Duration of fqs bursts (us)");
  96 module_param(fqs_holdoff, int, 0444);
  97 MODULE_PARM_DESC(fqs_holdoff, "Holdoff time within fqs bursts (us)");
  98 module_param(fqs_stutter, int, 0444);
  99 MODULE_PARM_DESC(fqs_stutter, "Wait time between fqs bursts (s)");
 100 module_param(n_barrier_cbs, int, 0444);
 101 MODULE_PARM_DESC(n_barrier_cbs, "# of callbacks/kthreads for barrier testing");
 102 module_param(onoff_interval, int, 0444);
 103 MODULE_PARM_DESC(onoff_interval, "Time between CPU hotplugs (s), 0=disable");
 104 module_param(onoff_holdoff, int, 0444);
 105 MODULE_PARM_DESC(onoff_holdoff, "Time after boot before CPU hotplugs (s)");
 106 module_param(shutdown_secs, int, 0444);
 107 MODULE_PARM_DESC(shutdown_secs, "Shutdown time (s), zero to disable.");
 108 module_param(stall_cpu, int, 0444);
 109 MODULE_PARM_DESC(stall_cpu, "Stall duration (s), zero to disable.");
 110 module_param(stall_cpu_holdoff, int, 0444);
 111 MODULE_PARM_DESC(stall_cpu_holdoff, "Time to wait before starting stall (s).");
 112 module_param(test_boost, int, 0444);
 113 MODULE_PARM_DESC(test_boost, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
 114 module_param(test_boost_interval, int, 0444);
 115 MODULE_PARM_DESC(test_boost_interval, "Interval between boost tests, seconds.");
 116 module_param(test_boost_duration, int, 0444);
 117 MODULE_PARM_DESC(test_boost_duration, "Duration of each boost test, seconds.");
 118 module_param(torture_type, charp, 0444);
 119 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, srcu)");
 120
 121 #define TORTURE_FLAG "-torture:"
 122 #define PRINTK_STRING(s) \
 123         do { pr_alert("%s" TORTURE_FLAG s "\n", torture_type); } while (0)
 124 #define VERBOSE_PRINTK_STRING(s) \
 125         do { if (verbose) pr_alert("%s" TORTURE_FLAG s "\n", torture_type); } while (0)
 126 #define VERBOSE_PRINTK_ERRSTRING(s) \
 127         do { if (verbose) pr_alert("%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
 128
 129 static char printk_buf[4096];
 130
 131 static int nrealreaders;
 132 static struct task_struct *writer_task;
 133 static struct task_struct **fakewriter_tasks;
 134 static struct task_struct **reader_tasks;
 135 static struct task_struct *stats_task;
 136 static struct task_struct *shuffler_task;
 137 static struct task_struct *stutter_task;
 138 static struct task_struct *fqs_task;
 139 static struct task_struct *boost_tasks[NR_CPUS];
 140 static struct task_struct *shutdown_task;
 141 #ifdef CONFIG_HOTPLUG_CPU
 142 static struct task_struct *onoff_task;
 143 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
 144 static struct task_struct *stall_task;
 145 static struct task_struct **barrier_cbs_tasks;
 146 static struct task_struct *barrier_task;
 147
 148 #define RCU_TORTURE_PIPE_LEN 10
 149
 150 struct rcu_torture {
 151         struct rcu_head rtort_rcu;
 152         int rtort_pipe_count;
 153         struct list_head rtort_free;
 154         int rtort_mbtest;
 155 };
 156
 157 static LIST_HEAD(rcu_torture_freelist);
 158 static struct rcu_torture __rcu *rcu_torture_current;
 159 static unsigned long rcu_torture_current_version;
 160 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 161 static DEFINE_SPINLOCK(rcu_torture_lock);
 162 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
 163         { 0 };
 164 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) =
 165         { 0 };
 166 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 167 static atomic_t n_rcu_torture_alloc;
 168 static atomic_t n_rcu_torture_alloc_fail;
 169 static atomic_t n_rcu_torture_free;
 170 static atomic_t n_rcu_torture_mberror;
 171 static atomic_t n_rcu_torture_error;
 172 static long n_rcu_torture_barrier_error;
 173 static long n_rcu_torture_boost_ktrerror;
 174 static long n_rcu_torture_boost_rterror;
 175 static long n_rcu_torture_boost_failure;
 176 static long n_rcu_torture_boosts;
 177 static long n_rcu_torture_timers;
 178 static long n_offline_attempts;
 179 static long n_offline_successes;
 180 static unsigned long sum_offline;
 181 static int min_offline = -1;
 182 static int max_offline;
 183 static long n_online_attempts;
 184 static long n_online_successes;
 185 static unsigned long sum_online;
 186 static int min_online = -1;
 187 static int max_online;
 188 static long n_barrier_attempts;
 189 static long n_barrier_successes;
 190 static struct list_head rcu_torture_removed;
 191 static cpumask_var_t shuffle_tmp_mask;
 192
 193 static int stutter_pause_test;
 194
 195 #if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
 196 #define RCUTORTURE_RUNNABLE_INIT 1
 197 #else
 198 #define RCUTORTURE_RUNNABLE_INIT 0
 199 #endif
 200 int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT;
 201 module_param(rcutorture_runnable, int, 0444);
 202 MODULE_PARM_DESC(rcutorture_runnable, "Start rcutorture at boot");
 203
 204 #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
 205 #define rcu_can_boost() 1
 206 #else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 207 #define rcu_can_boost() 0
 208 #endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 209
 210 static unsigned long shutdown_time;     /* jiffies to system shutdown. */
 211 static unsigned long boost_starttime;   /* jiffies of next boost test start. */
 212 DEFINE_MUTEX(boost_mutex);              /* protect setting boost_starttime */
 213                                         /*  and boost task create/destroy. */
 214 static atomic_t barrier_cbs_count;      /* Barrier callbacks registered. */
 215 static bool barrier_phase;              /* Test phase. */
 216 static atomic_t barrier_cbs_invoked;    /* Barrier callbacks invoked. */
 217 static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */
 218 static DECLARE_WAIT_QUEUE_HEAD(barrier_wq);
 219
 220 /* Mediate rmmod and system shutdown.  Concurrent rmmod & shutdown illegal! */
 221
 222 #define FULLSTOP_DONTSTOP 0     /* Normal operation. */
 223 #define FULLSTOP_SHUTDOWN 1     /* System shutdown with rcutorture running. */
 224 #define FULLSTOP_RMMOD    2     /* Normal rmmod of rcutorture. */
 225 static int fullstop = FULLSTOP_RMMOD;
 226 /*
 227  * Protect fullstop transitions and spawning of kthreads.
 228  */
 229 static DEFINE_MUTEX(fullstop_mutex);
 230
 231 /* Forward reference. */
 232 static void rcu_torture_cleanup(void);
 233
 234 /*
 235  * Detect and respond to a system shutdown.
 236  */
 237 static int
 238 rcutorture_shutdown_notify(struct notifier_block *unused1,
 239                            unsigned long unused2, void *unused3)
 240 {
 241         mutex_lock(&fullstop_mutex);
 242         if (fullstop == FULLSTOP_DONTSTOP)
 243                 fullstop = FULLSTOP_SHUTDOWN;
 244         else
 245                 pr_warn(/* but going down anyway, so... */
 246                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
 247         mutex_unlock(&fullstop_mutex);
 248         return NOTIFY_DONE;
 249 }
 250
 251 /*
 252  * Absorb kthreads into a kernel function that won't return, so that
 253  * they won't ever access module text or data again.
 254  */
 255 static void rcutorture_shutdown_absorb(char *title)
 256 {
 257         if (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
 258                 pr_notice(
 259                        "rcutorture thread %s parking due to system shutdown\n",
 260                        title);
 261                 schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
 262         }
 263 }
 264
 265 /*
 266  * Allocate an element from the rcu_tortures pool.
 267  */
 268 static struct rcu_torture *
 269 rcu_torture_alloc(void)
 270 {
 271         struct list_head *p;
 272
 273         spin_lock_bh(&rcu_torture_lock);
 274         if (list_empty(&rcu_torture_freelist)) {
 275                 atomic_inc(&n_rcu_torture_alloc_fail);
 276                 spin_unlock_bh(&rcu_torture_lock);
 277                 return NULL;
 278         }
 279         atomic_inc(&n_rcu_torture_alloc);
 280         p = rcu_torture_freelist.next;
 281         list_del_init(p);
 282         spin_unlock_bh(&rcu_torture_lock);
 283         return container_of(p, struct rcu_torture, rtort_free);
 284 }
 285
 286 /*
 287  * Free an element to the rcu_tortures pool.
 288  */
 289 static void
 290 rcu_torture_free(struct rcu_torture *p)
 291 {
 292         atomic_inc(&n_rcu_torture_free);
 293         spin_lock_bh(&rcu_torture_lock);
 294         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 295         spin_unlock_bh(&rcu_torture_lock);
 296 }
 297
 298 struct rcu_random_state {
 299         unsigned long rrs_state;
 300         long rrs_count;
 301 };
 302
 303 #define RCU_RANDOM_MULT 39916801  /* prime */
 304 #define RCU_RANDOM_ADD  479001701 /* prime */
 305 #define RCU_RANDOM_REFRESH 10000
 306
 307 #define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
 308
 309 /*
 310  * Crude but fast random-number generator.  Uses a linear congruential
 311  * generator, with occasional help from cpu_clock().
 312  */
 313 static unsigned long
 314 rcu_random(struct rcu_random_state *rrsp)
 315 {
 316         if (--rrsp->rrs_count < 0) {
 317                 rrsp->rrs_state += (unsigned long)local_clock();
 318                 rrsp->rrs_count = RCU_RANDOM_REFRESH;
 319         }
 320         rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
 321         return swahw32(rrsp->rrs_state);
 322 }
 323
 324 static void
 325 rcu_stutter_wait(char *title)
 326 {
 327         while (stutter_pause_test || !rcutorture_runnable) {
 328                 if (rcutorture_runnable)
 329                         schedule_timeout_interruptible(1);
 330                 else
 331                         schedule_timeout_interruptible(round_jiffies_relative(HZ));
 332                 rcutorture_shutdown_absorb(title);
 333         }
 334 }
 335
 336 /*
 337  * Operations vector for selecting different types of tests.
 338  */
 339
 340 struct rcu_torture_ops {
 341         void (*init)(void);
 342         void (*cleanup)(void);
 343         int (*readlock)(void);
 344         void (*read_delay)(struct rcu_random_state *rrsp);
 345         void (*readunlock)(int idx);
 346         int (*completed)(void);
 347         void (*deferred_free)(struct rcu_torture *p);
 348         void (*sync)(void);
 349         void (*call)(struct rcu_head *head, void (*func)(struct rcu_head *rcu));
 350         void (*cb_barrier)(void);
 351         void (*fqs)(void);
 352         int (*stats)(char *page);
 353         int irq_capable;
 354         int can_boost;
 355         char *name;
 356 };
 357
 358 static struct rcu_torture_ops *cur_ops;
 359
 360 /*
 361  * Definitions for rcu torture testing.
 362  */
 363
 364 static int rcu_torture_read_lock(void) __acquires(RCU)
 365 {
 366         rcu_read_lock();
 367         return 0;
 368 }
 369
 370 static void rcu_read_delay(struct rcu_random_state *rrsp)
 371 {
 372         const unsigned long shortdelay_us = 200;
 373         const unsigned long longdelay_ms = 50;
 374
 375         /* We want a short delay sometimes to make a reader delay the grace
 376          * period, and we want a long delay occasionally to trigger
 377          * force_quiescent_state. */
 378
 379         if (!(rcu_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
 380                 mdelay(longdelay_ms);
 381         if (!(rcu_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
 382                 udelay(shortdelay_us);
 383 #ifdef CONFIG_PREEMPT
 384         if (!preempt_count() && !(rcu_random(rrsp) % (nrealreaders * 20000)))
 385                 preempt_schedule();  /* No QS if preempt_disable() in effect */
 386 #endif
 387 }
 388
 389 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 390 {
 391         rcu_read_unlock();
 392 }
 393
 394 static int rcu_torture_completed(void)
 395 {
 396         return rcu_batches_completed();
 397 }
 398
 399 static void
 400 rcu_torture_cb(struct rcu_head *p)
 401 {
 402         int i;
 403         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 404
 405         if (fullstop != FULLSTOP_DONTSTOP) {
 406                 /* Test is ending, just drop callbacks on the floor. */
 407                 /* The next initialization will pick up the pieces. */
 408                 return;
 409         }
 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                 rcu_torture_free(rp);
 417         } else {
 418                 cur_ops->deferred_free(rp);
 419         }
 420 }
 421
 422 static int rcu_no_completed(void)
 423 {
 424         return 0;
 425 }
 426
 427 static void rcu_torture_deferred_free(struct rcu_torture *p)
 428 {
 429         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 430 }
 431
 432 static struct rcu_torture_ops rcu_ops = {
 433         .init           = NULL,
 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_torture_deferred_free,
 440         .sync           = synchronize_rcu,
 441         .call           = call_rcu,
 442         .cb_barrier     = rcu_barrier,
 443         .fqs            = rcu_force_quiescent_state,
 444         .stats          = NULL,
 445         .irq_capable    = 1,
 446         .can_boost      = rcu_can_boost(),
 447         .name           = "rcu"
 448 };
 449
 450 static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
 451 {
 452         int i;
 453         struct rcu_torture *rp;
 454         struct rcu_torture *rp1;
 455
 456         cur_ops->sync();
 457         list_add(&p->rtort_free, &rcu_torture_removed);
 458         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 459                 i = rp->rtort_pipe_count;
 460                 if (i > RCU_TORTURE_PIPE_LEN)
 461                         i = RCU_TORTURE_PIPE_LEN;
 462                 atomic_inc(&rcu_torture_wcount[i]);
 463                 if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 464                         rp->rtort_mbtest = 0;
 465                         list_del(&rp->rtort_free);
 466                         rcu_torture_free(rp);
 467                 }
 468         }
 469 }
 470
 471 static void rcu_sync_torture_init(void)
 472 {
 473         INIT_LIST_HEAD(&rcu_torture_removed);
 474 }
 475
 476 static struct rcu_torture_ops rcu_sync_ops = {
 477         .init           = rcu_sync_torture_init,
 478         .cleanup        = NULL,
 479         .readlock       = rcu_torture_read_lock,
 480         .read_delay     = rcu_read_delay,
 481         .readunlock     = rcu_torture_read_unlock,
 482         .completed      = rcu_torture_completed,
 483         .deferred_free  = rcu_sync_torture_deferred_free,
 484         .sync           = synchronize_rcu,
 485         .call           = NULL,
 486         .cb_barrier     = NULL,
 487         .fqs            = rcu_force_quiescent_state,
 488         .stats          = NULL,
 489         .irq_capable    = 1,
 490         .can_boost      = rcu_can_boost(),
 491         .name           = "rcu_sync"
 492 };
 493
 494 static struct rcu_torture_ops rcu_expedited_ops = {
 495         .init           = rcu_sync_torture_init,
 496         .cleanup        = NULL,
 497         .readlock       = rcu_torture_read_lock,
 498         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 499         .readunlock     = rcu_torture_read_unlock,
 500         .completed      = rcu_no_completed,
 501         .deferred_free  = rcu_sync_torture_deferred_free,
 502         .sync           = synchronize_rcu_expedited,
 503         .call           = NULL,
 504         .cb_barrier     = NULL,
 505         .fqs            = rcu_force_quiescent_state,
 506         .stats          = NULL,
 507         .irq_capable    = 1,
 508         .can_boost      = rcu_can_boost(),
 509         .name           = "rcu_expedited"
 510 };
 511
 512 /*
 513  * Definitions for rcu_bh torture testing.
 514  */
 515
 516 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
 517 {
 518         rcu_read_lock_bh();
 519         return 0;
 520 }
 521
 522 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
 523 {
 524         rcu_read_unlock_bh();
 525 }
 526
 527 static int rcu_bh_torture_completed(void)
 528 {
 529         return rcu_batches_completed_bh();
 530 }
 531
 532 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 533 {
 534         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
 535 }
 536
 537 static struct rcu_torture_ops rcu_bh_ops = {
 538         .init           = NULL,
 539         .cleanup        = NULL,
 540         .readlock       = rcu_bh_torture_read_lock,
 541         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 542         .readunlock     = rcu_bh_torture_read_unlock,
 543         .completed      = rcu_bh_torture_completed,
 544         .deferred_free  = rcu_bh_torture_deferred_free,
 545         .sync           = synchronize_rcu_bh,
 546         .call           = call_rcu_bh,
 547         .cb_barrier     = rcu_barrier_bh,
 548         .fqs            = rcu_bh_force_quiescent_state,
 549         .stats          = NULL,
 550         .irq_capable    = 1,
 551         .name           = "rcu_bh"
 552 };
 553
 554 static struct rcu_torture_ops rcu_bh_sync_ops = {
 555         .init           = rcu_sync_torture_init,
 556         .cleanup        = NULL,
 557         .readlock       = rcu_bh_torture_read_lock,
 558         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 559         .readunlock     = rcu_bh_torture_read_unlock,
 560         .completed      = rcu_bh_torture_completed,
 561         .deferred_free  = rcu_sync_torture_deferred_free,
 562         .sync           = synchronize_rcu_bh,
 563         .call           = NULL,
 564         .cb_barrier     = NULL,
 565         .fqs            = rcu_bh_force_quiescent_state,
 566         .stats          = NULL,
 567         .irq_capable    = 1,
 568         .name           = "rcu_bh_sync"
 569 };
 570
 571 static struct rcu_torture_ops rcu_bh_expedited_ops = {
 572         .init           = rcu_sync_torture_init,
 573         .cleanup        = NULL,
 574         .readlock       = rcu_bh_torture_read_lock,
 575         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 576         .readunlock     = rcu_bh_torture_read_unlock,
 577         .completed      = rcu_bh_torture_completed,
 578         .deferred_free  = rcu_sync_torture_deferred_free,
 579         .sync           = synchronize_rcu_bh_expedited,
 580         .call           = NULL,
 581         .cb_barrier     = NULL,
 582         .fqs            = rcu_bh_force_quiescent_state,
 583         .stats          = NULL,
 584         .irq_capable    = 1,
 585         .name           = "rcu_bh_expedited"
 586 };
 587
 588 /*
 589  * Definitions for srcu torture testing.
 590  */
 591
 592 static struct srcu_struct srcu_ctl;
 593
 594 static void srcu_torture_init(void)
 595 {
 596         init_srcu_struct(&srcu_ctl);
 597         rcu_sync_torture_init();
 598 }
 599
 600 static void srcu_torture_cleanup(void)
 601 {
 602         synchronize_srcu(&srcu_ctl);
 603         cleanup_srcu_struct(&srcu_ctl);
 604 }
 605
 606 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
 607 {
 608         return srcu_read_lock(&srcu_ctl);
 609 }
 610
 611 static void srcu_read_delay(struct rcu_random_state *rrsp)
 612 {
 613         long delay;
 614         const long uspertick = 1000000 / HZ;
 615         const long longdelay = 10;
 616
 617         /* We want there to be long-running readers, but not all the time. */
 618
 619         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
 620         if (!delay)
 621                 schedule_timeout_interruptible(longdelay);
 622         else
 623                 rcu_read_delay(rrsp);
 624 }
 625
 626 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
 627 {
 628         srcu_read_unlock(&srcu_ctl, idx);
 629 }
 630
 631 static int srcu_torture_completed(void)
 632 {
 633         return srcu_batches_completed(&srcu_ctl);
 634 }
 635
 636 static void srcu_torture_deferred_free(struct rcu_torture *rp)
 637 {
 638         call_srcu(&srcu_ctl, &rp->rtort_rcu, rcu_torture_cb);
 639 }
 640
 641 static void srcu_torture_synchronize(void)
 642 {
 643         synchronize_srcu(&srcu_ctl);
 644 }
 645
 646 static void srcu_torture_call(struct rcu_head *head,
 647                               void (*func)(struct rcu_head *head))
 648 {
 649         call_srcu(&srcu_ctl, head, func);
 650 }
 651
 652 static void srcu_torture_barrier(void)
 653 {
 654         srcu_barrier(&srcu_ctl);
 655 }
 656
 657 static int srcu_torture_stats(char *page)
 658 {
 659         int cnt = 0;
 660         int cpu;
 661         int idx = srcu_ctl.completed & 0x1;
 662
 663         cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
 664                        torture_type, TORTURE_FLAG, idx);
 665         for_each_possible_cpu(cpu) {
 666                 cnt += sprintf(&page[cnt], " %d(%lu,%lu)", cpu,
 667                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
 668                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
 669         }
 670         cnt += sprintf(&page[cnt], "\n");
 671         return cnt;
 672 }
 673
 674 static struct rcu_torture_ops srcu_ops = {
 675         .init           = srcu_torture_init,
 676         .cleanup        = srcu_torture_cleanup,
 677         .readlock       = srcu_torture_read_lock,
 678         .read_delay     = srcu_read_delay,
 679         .readunlock     = srcu_torture_read_unlock,
 680         .completed      = srcu_torture_completed,
 681         .deferred_free  = srcu_torture_deferred_free,
 682         .sync           = srcu_torture_synchronize,
 683         .call           = srcu_torture_call,
 684         .cb_barrier     = srcu_torture_barrier,
 685         .stats          = srcu_torture_stats,
 686         .name           = "srcu"
 687 };
 688
 689 static struct rcu_torture_ops srcu_sync_ops = {
 690         .init           = srcu_torture_init,
 691         .cleanup        = srcu_torture_cleanup,
 692         .readlock       = srcu_torture_read_lock,
 693         .read_delay     = srcu_read_delay,
 694         .readunlock     = srcu_torture_read_unlock,
 695         .completed      = srcu_torture_completed,
 696         .deferred_free  = rcu_sync_torture_deferred_free,
 697         .sync           = srcu_torture_synchronize,
 698         .call           = NULL,
 699         .cb_barrier     = NULL,
 700         .stats          = srcu_torture_stats,
 701         .name           = "srcu_sync"
 702 };
 703
 704 static int srcu_torture_read_lock_raw(void) __acquires(&srcu_ctl)
 705 {
 706         return srcu_read_lock_raw(&srcu_ctl);
 707 }
 708
 709 static void srcu_torture_read_unlock_raw(int idx) __releases(&srcu_ctl)
 710 {
 711         srcu_read_unlock_raw(&srcu_ctl, idx);
 712 }
 713
 714 static struct rcu_torture_ops srcu_raw_ops = {
 715         .init           = srcu_torture_init,
 716         .cleanup        = srcu_torture_cleanup,
 717         .readlock       = srcu_torture_read_lock_raw,
 718         .read_delay     = srcu_read_delay,
 719         .readunlock     = srcu_torture_read_unlock_raw,
 720         .completed      = srcu_torture_completed,
 721         .deferred_free  = srcu_torture_deferred_free,
 722         .sync           = srcu_torture_synchronize,
 723         .call           = NULL,
 724         .cb_barrier     = NULL,
 725         .stats          = srcu_torture_stats,
 726         .name           = "srcu_raw"
 727 };
 728
 729 static struct rcu_torture_ops srcu_raw_sync_ops = {
 730         .init           = srcu_torture_init,
 731         .cleanup        = srcu_torture_cleanup,
 732         .readlock       = srcu_torture_read_lock_raw,
 733         .read_delay     = srcu_read_delay,
 734         .readunlock     = srcu_torture_read_unlock_raw,
 735         .completed      = srcu_torture_completed,
 736         .deferred_free  = rcu_sync_torture_deferred_free,
 737         .sync           = srcu_torture_synchronize,
 738         .call           = NULL,
 739         .cb_barrier     = NULL,
 740         .stats          = srcu_torture_stats,
 741         .name           = "srcu_raw_sync"
 742 };
 743
 744 static void srcu_torture_synchronize_expedited(void)
 745 {
 746         synchronize_srcu_expedited(&srcu_ctl);
 747 }
 748
 749 static struct rcu_torture_ops srcu_expedited_ops = {
 750         .init           = srcu_torture_init,
 751         .cleanup        = srcu_torture_cleanup,
 752         .readlock       = srcu_torture_read_lock,
 753         .read_delay     = srcu_read_delay,
 754         .readunlock     = srcu_torture_read_unlock,
 755         .completed      = srcu_torture_completed,
 756         .deferred_free  = rcu_sync_torture_deferred_free,
 757         .sync           = srcu_torture_synchronize_expedited,
 758         .call           = NULL,
 759         .cb_barrier     = NULL,
 760         .stats          = srcu_torture_stats,
 761         .name           = "srcu_expedited"
 762 };
 763
 764 /*
 765  * Definitions for sched torture testing.
 766  */
 767
 768 static int sched_torture_read_lock(void)
 769 {
 770         preempt_disable();
 771         return 0;
 772 }
 773
 774 static void sched_torture_read_unlock(int idx)
 775 {
 776         preempt_enable();
 777 }
 778
 779 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
 780 {
 781         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
 782 }
 783
 784 static struct rcu_torture_ops sched_ops = {
 785         .init           = rcu_sync_torture_init,
 786         .cleanup        = NULL,
 787         .readlock       = sched_torture_read_lock,
 788         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 789         .readunlock     = sched_torture_read_unlock,
 790         .completed      = rcu_no_completed,
 791         .deferred_free  = rcu_sched_torture_deferred_free,
 792         .sync           = synchronize_sched,
 793         .cb_barrier     = rcu_barrier_sched,
 794         .fqs            = rcu_sched_force_quiescent_state,
 795         .stats          = NULL,
 796         .irq_capable    = 1,
 797         .name           = "sched"
 798 };
 799
 800 static struct rcu_torture_ops sched_sync_ops = {
 801         .init           = rcu_sync_torture_init,
 802         .cleanup        = NULL,
 803         .readlock       = sched_torture_read_lock,
 804         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 805         .readunlock     = sched_torture_read_unlock,
 806         .completed      = rcu_no_completed,
 807         .deferred_free  = rcu_sync_torture_deferred_free,
 808         .sync           = synchronize_sched,
 809         .cb_barrier     = NULL,
 810         .fqs            = rcu_sched_force_quiescent_state,
 811         .stats          = NULL,
 812         .name           = "sched_sync"
 813 };
 814
 815 static struct rcu_torture_ops sched_expedited_ops = {
 816         .init           = rcu_sync_torture_init,
 817         .cleanup        = NULL,
 818         .readlock       = sched_torture_read_lock,
 819         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 820         .readunlock     = sched_torture_read_unlock,
 821         .completed      = rcu_no_completed,
 822         .deferred_free  = rcu_sync_torture_deferred_free,
 823         .sync           = synchronize_sched_expedited,
 824         .cb_barrier     = NULL,
 825         .fqs            = rcu_sched_force_quiescent_state,
 826         .stats          = NULL,
 827         .irq_capable    = 1,
 828         .name           = "sched_expedited"
 829 };
 830
 831 /*
 832  * RCU torture priority-boost testing.  Runs one real-time thread per
 833  * CPU for moderate bursts, repeatedly registering RCU callbacks and
 834  * spinning waiting for them to be invoked.  If a given callback takes
 835  * too long to be invoked, we assume that priority inversion has occurred.
 836  */
 837
 838 struct rcu_boost_inflight {
 839         struct rcu_head rcu;
 840         int inflight;
 841 };
 842
 843 static void rcu_torture_boost_cb(struct rcu_head *head)
 844 {
 845         struct rcu_boost_inflight *rbip =
 846                 container_of(head, struct rcu_boost_inflight, rcu);
 847
 848         smp_mb(); /* Ensure RCU-core accesses precede clearing ->inflight */
 849         rbip->inflight = 0;
 850 }
 851
 852 static int rcu_torture_boost(void *arg)
 853 {
 854         unsigned long call_rcu_time;
 855         unsigned long endtime;
 856         unsigned long oldstarttime;
 857         struct rcu_boost_inflight rbi = { .inflight = 0 };
 858         struct sched_param sp;
 859
 860         VERBOSE_PRINTK_STRING("rcu_torture_boost started");
 861
 862         /* Set real-time priority. */
 863         sp.sched_priority = 1;
 864         if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 865                 VERBOSE_PRINTK_STRING("rcu_torture_boost RT prio failed!");
 866                 n_rcu_torture_boost_rterror++;
 867         }
 868
 869         init_rcu_head_on_stack(&rbi.rcu);
 870         /* Each pass through the following loop does one boost-test cycle. */
 871         do {
 872                 /* Wait for the next test interval. */
 873                 oldstarttime = boost_starttime;
 874                 while (ULONG_CMP_LT(jiffies, oldstarttime)) {
 875                         schedule_timeout_uninterruptible(1);
 876                         rcu_stutter_wait("rcu_torture_boost");
 877                         if (kthread_should_stop() ||
 878                             fullstop != FULLSTOP_DONTSTOP)
 879                                 goto checkwait;
 880                 }
 881
 882                 /* Do one boost-test interval. */
 883                 endtime = oldstarttime + test_boost_duration * HZ;
 884                 call_rcu_time = jiffies;
 885                 while (ULONG_CMP_LT(jiffies, endtime)) {
 886                         /* If we don't have a callback in flight, post one. */
 887                         if (!rbi.inflight) {
 888                                 smp_mb(); /* RCU core before ->inflight = 1. */
 889                                 rbi.inflight = 1;
 890                                 call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 891                                 if (jiffies - call_rcu_time >
 892                                          test_boost_duration * HZ - HZ / 2) {
 893                                         VERBOSE_PRINTK_STRING("rcu_torture_boost boosting failed");
 894                                         n_rcu_torture_boost_failure++;
 895                                 }
 896                                 call_rcu_time = jiffies;
 897                         }
 898                         cond_resched();
 899                         rcu_stutter_wait("rcu_torture_boost");
 900                         if (kthread_should_stop() ||
 901                             fullstop != FULLSTOP_DONTSTOP)
 902                                 goto checkwait;
 903                 }
 904
 905                 /*
 906                  * Set the start time of the next test interval.
 907                  * Yes, this is vulnerable to long delays, but such
 908                  * delays simply cause a false negative for the next
 909                  * interval.  Besides, we are running at RT priority,
 910                  * so delays should be relatively rare.
 911                  */
 912                 while (oldstarttime == boost_starttime &&
 913                        !kthread_should_stop()) {
 914                         if (mutex_trylock(&boost_mutex)) {
 915                                 boost_starttime = jiffies +
 916                                                   test_boost_interval * HZ;
 917                                 n_rcu_torture_boosts++;
 918                                 mutex_unlock(&boost_mutex);
 919                                 break;
 920                         }
 921                         schedule_timeout_uninterruptible(1);
 922                 }
 923
 924                 /* Go do the stutter. */
 925 checkwait:      rcu_stutter_wait("rcu_torture_boost");
 926         } while (!kthread_should_stop() && fullstop  == FULLSTOP_DONTSTOP);
 927
 928         /* Clean up and exit. */
 929         VERBOSE_PRINTK_STRING("rcu_torture_boost task stopping");
 930         rcutorture_shutdown_absorb("rcu_torture_boost");
 931         while (!kthread_should_stop() || rbi.inflight)
 932                 schedule_timeout_uninterruptible(1);
 933         smp_mb(); /* order accesses to ->inflight before stack-frame death. */
 934         destroy_rcu_head_on_stack(&rbi.rcu);
 935         return 0;
 936 }
 937
 938 /*
 939  * RCU torture force-quiescent-state kthread.  Repeatedly induces
 940  * bursts of calls to force_quiescent_state(), increasing the probability
 941  * of occurrence of some important types of race conditions.
 942  */
 943 static int
 944 rcu_torture_fqs(void *arg)
 945 {
 946         unsigned long fqs_resume_time;
 947         int fqs_burst_remaining;
 948
 949         VERBOSE_PRINTK_STRING("rcu_torture_fqs task started");
 950         do {
 951                 fqs_resume_time = jiffies + fqs_stutter * HZ;
 952                 while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
 953                        !kthread_should_stop()) {
 954                         schedule_timeout_interruptible(1);
 955                 }
 956                 fqs_burst_remaining = fqs_duration;
 957                 while (fqs_burst_remaining > 0 &&
 958                        !kthread_should_stop()) {
 959                         cur_ops->fqs();
 960                         udelay(fqs_holdoff);
 961                         fqs_burst_remaining -= fqs_holdoff;
 962                 }
 963                 rcu_stutter_wait("rcu_torture_fqs");
 964         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 965         VERBOSE_PRINTK_STRING("rcu_torture_fqs task stopping");
 966         rcutorture_shutdown_absorb("rcu_torture_fqs");
 967         while (!kthread_should_stop())
 968                 schedule_timeout_uninterruptible(1);
 969         return 0;
 970 }
 971
 972 /*
 973  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 974  * for that pointed to by rcu_torture_current, freeing the old structure
 975  * after a series of grace periods (the "pipeline").
 976  */
 977 static int
 978 rcu_torture_writer(void *arg)
 979 {
 980         int i;
 981         long oldbatch = rcu_batches_completed();
 982         struct rcu_torture *rp;
 983         struct rcu_torture *old_rp;
 984         static DEFINE_RCU_RANDOM(rand);
 985
 986         VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
 987         set_user_nice(current, 19);
 988
 989         do {
 990                 schedule_timeout_uninterruptible(1);
 991                 rp = rcu_torture_alloc();
 992                 if (rp == NULL)
 993                         continue;
 994                 rp->rtort_pipe_count = 0;
 995                 udelay(rcu_random(&rand) & 0x3ff);
 996                 old_rp = rcu_dereference_check(rcu_torture_current,
 997                                                current == writer_task);
 998                 rp->rtort_mbtest = 1;
 999                 rcu_assign_pointer(rcu_torture_current, rp);
1000                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
1001                 if (old_rp) {
1002                         i = old_rp->rtort_pipe_count;
1003                         if (i > RCU_TORTURE_PIPE_LEN)
1004                                 i = RCU_TORTURE_PIPE_LEN;
1005                         atomic_inc(&rcu_torture_wcount[i]);
1006                         old_rp->rtort_pipe_count++;
1007                         cur_ops->deferred_free(old_rp);
1008                 }
1009                 rcutorture_record_progress(++rcu_torture_current_version);
1010                 oldbatch = cur_ops->completed();
1011                 rcu_stutter_wait("rcu_torture_writer");
1012         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1013         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
1014         rcutorture_shutdown_absorb("rcu_torture_writer");
1015         while (!kthread_should_stop())
1016                 schedule_timeout_uninterruptible(1);
1017         return 0;
1018 }
1019
1020 /*
1021  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
1022  * delay between calls.
1023  */
1024 static int
1025 rcu_torture_fakewriter(void *arg)
1026 {
1027         DEFINE_RCU_RANDOM(rand);
1028
1029         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
1030         set_user_nice(current, 19);
1031
1032         do {
1033                 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
1034                 udelay(rcu_random(&rand) & 0x3ff);
1035                 if (cur_ops->cb_barrier != NULL &&
1036                     rcu_random(&rand) % (nfakewriters * 8) == 0)
1037                         cur_ops->cb_barrier();
1038                 else
1039                         cur_ops->sync();
1040                 rcu_stutter_wait("rcu_torture_fakewriter");
1041         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1042
1043         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
1044         rcutorture_shutdown_absorb("rcu_torture_fakewriter");
1045         while (!kthread_should_stop())
1046                 schedule_timeout_uninterruptible(1);
1047         return 0;
1048 }
1049
1050 void rcutorture_trace_dump(void)
1051 {
1052         static atomic_t beenhere = ATOMIC_INIT(0);
1053
1054         if (atomic_read(&beenhere))
1055                 return;
1056         if (atomic_xchg(&beenhere, 1) != 0)
1057                 return;
1058         do_trace_rcu_torture_read(cur_ops->name, (struct rcu_head *)~0UL);
1059         ftrace_dump(DUMP_ALL);
1060 }
1061
1062 /*
1063  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
1064  * incrementing the corresponding element of the pipeline array.  The
1065  * counter in the element should never be greater than 1, otherwise, the
1066  * RCU implementation is broken.
1067  */
1068 static void rcu_torture_timer(unsigned long unused)
1069 {
1070         int idx;
1071         int completed;
1072         static DEFINE_RCU_RANDOM(rand);
1073         static DEFINE_SPINLOCK(rand_lock);
1074         struct rcu_torture *p;
1075         int pipe_count;
1076
1077         idx = cur_ops->readlock();
1078         completed = cur_ops->completed();
1079         p = rcu_dereference_check(rcu_torture_current,
1080                                   rcu_read_lock_bh_held() ||
1081                                   rcu_read_lock_sched_held() ||
1082                                   srcu_read_lock_held(&srcu_ctl));
1083         if (p == NULL) {
1084                 /* Leave because rcu_torture_writer is not yet underway */
1085                 cur_ops->readunlock(idx);
1086                 return;
1087         }
1088         do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu);
1089         if (p->rtort_mbtest == 0)
1090                 atomic_inc(&n_rcu_torture_mberror);
1091         spin_lock(&rand_lock);
1092         cur_ops->read_delay(&rand);
1093         n_rcu_torture_timers++;
1094         spin_unlock(&rand_lock);
1095         preempt_disable();
1096         pipe_count = p->rtort_pipe_count;
1097         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1098                 /* Should not happen, but... */
1099                 pipe_count = RCU_TORTURE_PIPE_LEN;
1100         }
1101         if (pipe_count > 1)
1102                 rcutorture_trace_dump();
1103         __this_cpu_inc(rcu_torture_count[pipe_count]);
1104         completed = cur_ops->completed() - completed;
1105         if (completed > RCU_TORTURE_PIPE_LEN) {
1106                 /* Should not happen, but... */
1107                 completed = RCU_TORTURE_PIPE_LEN;
1108         }
1109         __this_cpu_inc(rcu_torture_batch[completed]);
1110         preempt_enable();
1111         cur_ops->readunlock(idx);
1112 }
1113
1114 /*
1115  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
1116  * incrementing the corresponding element of the pipeline array.  The
1117  * counter in the element should never be greater than 1, otherwise, the
1118  * RCU implementation is broken.
1119  */
1120 static int
1121 rcu_torture_reader(void *arg)
1122 {
1123         int completed;
1124         int idx;
1125         DEFINE_RCU_RANDOM(rand);
1126         struct rcu_torture *p;
1127         int pipe_count;
1128         struct timer_list t;
1129
1130         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
1131         set_user_nice(current, 19);
1132         if (irqreader && cur_ops->irq_capable)
1133                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
1134
1135         do {
1136                 if (irqreader && cur_ops->irq_capable) {
1137                         if (!timer_pending(&t))
1138                                 mod_timer(&t, jiffies + 1);
1139                 }
1140                 idx = cur_ops->readlock();
1141                 completed = cur_ops->completed();
1142                 p = rcu_dereference_check(rcu_torture_current,
1143                                           rcu_read_lock_bh_held() ||
1144                                           rcu_read_lock_sched_held() ||
1145                                           srcu_read_lock_held(&srcu_ctl));
1146                 if (p == NULL) {
1147                         /* Wait for rcu_torture_writer to get underway */
1148                         cur_ops->readunlock(idx);
1149                         schedule_timeout_interruptible(HZ);
1150                         continue;
1151                 }
1152                 do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu);
1153                 if (p->rtort_mbtest == 0)
1154                         atomic_inc(&n_rcu_torture_mberror);
1155                 cur_ops->read_delay(&rand);
1156                 preempt_disable();
1157                 pipe_count = p->rtort_pipe_count;
1158                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1159                         /* Should not happen, but... */
1160                         pipe_count = RCU_TORTURE_PIPE_LEN;
1161                 }
1162                 if (pipe_count > 1)
1163                         rcutorture_trace_dump();
1164                 __this_cpu_inc(rcu_torture_count[pipe_count]);
1165                 completed = cur_ops->completed() - completed;
1166                 if (completed > RCU_TORTURE_PIPE_LEN) {
1167                         /* Should not happen, but... */
1168                         completed = RCU_TORTURE_PIPE_LEN;
1169                 }
1170                 __this_cpu_inc(rcu_torture_batch[completed]);
1171                 preempt_enable();
1172                 cur_ops->readunlock(idx);
1173                 schedule();
1174                 rcu_stutter_wait("rcu_torture_reader");
1175         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1176         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
1177         rcutorture_shutdown_absorb("rcu_torture_reader");
1178         if (irqreader && cur_ops->irq_capable)
1179                 del_timer_sync(&t);
1180         while (!kthread_should_stop())
1181                 schedule_timeout_uninterruptible(1);
1182         return 0;
1183 }
1184
1185 /*
1186  * Create an RCU-torture statistics message in the specified buffer.
1187  */
1188 static int
1189 rcu_torture_printk(char *page)
1190 {
1191         int cnt = 0;
1192         int cpu;
1193         int i;
1194         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1195         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1196
1197         for_each_possible_cpu(cpu) {
1198                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1199                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1200                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1201                 }
1202         }
1203         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1204                 if (pipesummary[i] != 0)
1205                         break;
1206         }
1207         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
1208         cnt += sprintf(&page[cnt],
1209                        "rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
1210                        rcu_torture_current,
1211                        rcu_torture_current_version,
1212                        list_empty(&rcu_torture_freelist),
1213                        atomic_read(&n_rcu_torture_alloc),
1214                        atomic_read(&n_rcu_torture_alloc_fail),
1215                        atomic_read(&n_rcu_torture_free));
1216         cnt += sprintf(&page[cnt], "rtmbe: %d rtbke: %ld rtbre: %ld ",
1217                        atomic_read(&n_rcu_torture_mberror),
1218                        n_rcu_torture_boost_ktrerror,
1219                        n_rcu_torture_boost_rterror);
1220         cnt += sprintf(&page[cnt], "rtbf: %ld rtb: %ld nt: %ld ",
1221                        n_rcu_torture_boost_failure,
1222                        n_rcu_torture_boosts,
1223                        n_rcu_torture_timers);
1224         cnt += sprintf(&page[cnt],
1225                        "onoff: %ld/%ld:%ld/%ld %d,%d:%d,%d %lu:%lu (HZ=%d) ",
1226                        n_online_successes, n_online_attempts,
1227                        n_offline_successes, n_offline_attempts,
1228                        min_online, max_online,
1229                        min_offline, max_offline,
1230                        sum_online, sum_offline, HZ);
1231         cnt += sprintf(&page[cnt], "barrier: %ld/%ld:%ld",
1232                        n_barrier_successes,
1233                        n_barrier_attempts,
1234                        n_rcu_torture_barrier_error);
1235         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1236         if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1237             n_rcu_torture_barrier_error != 0 ||
1238             n_rcu_torture_boost_ktrerror != 0 ||
1239             n_rcu_torture_boost_rterror != 0 ||
1240             n_rcu_torture_boost_failure != 0 ||
1241             i > 1) {
1242                 cnt += sprintf(&page[cnt], "!!! ");
1243                 atomic_inc(&n_rcu_torture_error);
1244                 WARN_ON_ONCE(1);
1245         }
1246         cnt += sprintf(&page[cnt], "Reader Pipe: ");
1247         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1248                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
1249         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1250         cnt += sprintf(&page[cnt], "Reader Batch: ");
1251         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1252                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
1253         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1254         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
1255         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1256                 cnt += sprintf(&page[cnt], " %d",
1257                                atomic_read(&rcu_torture_wcount[i]));
1258         }
1259         cnt += sprintf(&page[cnt], "\n");
1260         if (cur_ops->stats)
1261                 cnt += cur_ops->stats(&page[cnt]);
1262         return cnt;
1263 }
1264
1265 /*
1266  * Print torture statistics.  Caller must ensure that there is only
1267  * one call to this function at a given time!!!  This is normally
1268  * accomplished by relying on the module system to only have one copy
1269  * of the module loaded, and then by giving the rcu_torture_stats
1270  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1271  * thread is not running).
1272  */
1273 static void
1274 rcu_torture_stats_print(void)
1275 {
1276         int cnt;
1277
1278         cnt = rcu_torture_printk(printk_buf);
1279         pr_alert("%s", printk_buf);
1280 }
1281
1282 /*
1283  * Periodically prints torture statistics, if periodic statistics printing
1284  * was specified via the stat_interval module parameter.
1285  *
1286  * No need to worry about fullstop here, since this one doesn't reference
1287  * volatile state or register callbacks.
1288  */
1289 static int
1290 rcu_torture_stats(void *arg)
1291 {
1292         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
1293         do {
1294                 schedule_timeout_interruptible(stat_interval * HZ);
1295                 rcu_torture_stats_print();
1296                 rcutorture_shutdown_absorb("rcu_torture_stats");
1297         } while (!kthread_should_stop());
1298         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
1299         return 0;
1300 }
1301
1302 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
1303
1304 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
1305  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
1306  */
1307 static void rcu_torture_shuffle_tasks(void)
1308 {
1309         int i;
1310
1311         cpumask_setall(shuffle_tmp_mask);
1312         get_online_cpus();
1313
1314         /* No point in shuffling if there is only one online CPU (ex: UP) */
1315         if (num_online_cpus() == 1) {
1316                 put_online_cpus();
1317                 return;
1318         }
1319
1320         if (rcu_idle_cpu != -1)
1321                 cpumask_clear_cpu(rcu_idle_cpu, shuffle_tmp_mask);
1322
1323         set_cpus_allowed_ptr(current, shuffle_tmp_mask);
1324
1325         if (reader_tasks) {
1326                 for (i = 0; i < nrealreaders; i++)
1327                         if (reader_tasks[i])
1328                                 set_cpus_allowed_ptr(reader_tasks[i],
1329                                                      shuffle_tmp_mask);
1330         }
1331
1332         if (fakewriter_tasks) {
1333                 for (i = 0; i < nfakewriters; i++)
1334                         if (fakewriter_tasks[i])
1335                                 set_cpus_allowed_ptr(fakewriter_tasks[i],
1336                                                      shuffle_tmp_mask);
1337         }
1338
1339         if (writer_task)
1340                 set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
1341
1342         if (stats_task)
1343                 set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
1344
1345         if (rcu_idle_cpu == -1)
1346                 rcu_idle_cpu = num_online_cpus() - 1;
1347         else
1348                 rcu_idle_cpu--;
1349
1350         put_online_cpus();
1351 }
1352
1353 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
1354  * system to become idle at a time and cut off its timer ticks. This is meant
1355  * to test the support for such tickless idle CPU in RCU.
1356  */
1357 static int
1358 rcu_torture_shuffle(void *arg)
1359 {
1360         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
1361         do {
1362                 schedule_timeout_interruptible(shuffle_interval * HZ);
1363                 rcu_torture_shuffle_tasks();
1364                 rcutorture_shutdown_absorb("rcu_torture_shuffle");
1365         } while (!kthread_should_stop());
1366         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
1367         return 0;
1368 }
1369
1370 /* Cause the rcutorture test to "stutter", starting and stopping all
1371  * threads periodically.
1372  */
1373 static int
1374 rcu_torture_stutter(void *arg)
1375 {
1376         VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
1377         do {
1378                 schedule_timeout_interruptible(stutter * HZ);
1379                 stutter_pause_test = 1;
1380                 if (!kthread_should_stop())
1381                         schedule_timeout_interruptible(stutter * HZ);
1382                 stutter_pause_test = 0;
1383                 rcutorture_shutdown_absorb("rcu_torture_stutter");
1384         } while (!kthread_should_stop());
1385         VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
1386         return 0;
1387 }
1388
1389 static inline void
1390 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, char *tag)
1391 {
1392         pr_alert("%s" TORTURE_FLAG
1393                  "--- %s: nreaders=%d nfakewriters=%d "
1394                  "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1395                  "shuffle_interval=%d stutter=%d irqreader=%d "
1396                  "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1397                  "test_boost=%d/%d test_boost_interval=%d "
1398                  "test_boost_duration=%d shutdown_secs=%d "
1399                  "onoff_interval=%d onoff_holdoff=%d\n",
1400                  torture_type, tag, nrealreaders, nfakewriters,
1401                  stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1402                  stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1403                  test_boost, cur_ops->can_boost,
1404                  test_boost_interval, test_boost_duration, shutdown_secs,
1405                  onoff_interval, onoff_holdoff);
1406 }
1407
1408 static struct notifier_block rcutorture_shutdown_nb = {
1409         .notifier_call = rcutorture_shutdown_notify,
1410 };
1411
1412 static void rcutorture_booster_cleanup(int cpu)
1413 {
1414         struct task_struct *t;
1415
1416         if (boost_tasks[cpu] == NULL)
1417                 return;
1418         mutex_lock(&boost_mutex);
1419         VERBOSE_PRINTK_STRING("Stopping rcu_torture_boost task");
1420         t = boost_tasks[cpu];
1421         boost_tasks[cpu] = NULL;
1422         mutex_unlock(&boost_mutex);
1423
1424         /* This must be outside of the mutex, otherwise deadlock! */
1425         kthread_stop(t);
1426         boost_tasks[cpu] = NULL;
1427 }
1428
1429 static int rcutorture_booster_init(int cpu)
1430 {
1431         int retval;
1432
1433         if (boost_tasks[cpu] != NULL)
1434                 return 0;  /* Already created, nothing more to do. */
1435
1436         /* Don't allow time recalculation while creating a new task. */
1437         mutex_lock(&boost_mutex);
1438         VERBOSE_PRINTK_STRING("Creating rcu_torture_boost task");
1439         boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1440                                                   cpu_to_node(cpu),
1441                                                   "rcu_torture_boost");
1442         if (IS_ERR(boost_tasks[cpu])) {
1443                 retval = PTR_ERR(boost_tasks[cpu]);
1444                 VERBOSE_PRINTK_STRING("rcu_torture_boost task create failed");
1445                 n_rcu_torture_boost_ktrerror++;
1446                 boost_tasks[cpu] = NULL;
1447                 mutex_unlock(&boost_mutex);
1448                 return retval;
1449         }
1450         kthread_bind(boost_tasks[cpu], cpu);
1451         wake_up_process(boost_tasks[cpu]);
1452         mutex_unlock(&boost_mutex);
1453         return 0;
1454 }
1455
1456 /*
1457  * Cause the rcutorture test to shutdown the system after the test has
1458  * run for the time specified by the shutdown_secs module parameter.
1459  */
1460 static int
1461 rcu_torture_shutdown(void *arg)
1462 {
1463         long delta;
1464         unsigned long jiffies_snap;
1465
1466         VERBOSE_PRINTK_STRING("rcu_torture_shutdown task started");
1467         jiffies_snap = ACCESS_ONCE(jiffies);
1468         while (ULONG_CMP_LT(jiffies_snap, shutdown_time) &&
1469                !kthread_should_stop()) {
1470                 delta = shutdown_time - jiffies_snap;
1471                 if (verbose)
1472                         pr_alert("%s" TORTURE_FLAG
1473                                  "rcu_torture_shutdown task: %lu jiffies remaining\n",
1474                                  torture_type, delta);
1475                 schedule_timeout_interruptible(delta);
1476                 jiffies_snap = ACCESS_ONCE(jiffies);
1477         }
1478         if (kthread_should_stop()) {
1479                 VERBOSE_PRINTK_STRING("rcu_torture_shutdown task stopping");
1480                 return 0;
1481         }
1482
1483         /* OK, shut down the system. */
1484
1485         VERBOSE_PRINTK_STRING("rcu_torture_shutdown task shutting down system");
1486         shutdown_task = NULL;   /* Avoid self-kill deadlock. */
1487         rcu_torture_cleanup();  /* Get the success/failure message. */
1488         kernel_power_off();     /* Shut down the system. */
1489         return 0;
1490 }
1491
1492 #ifdef CONFIG_HOTPLUG_CPU
1493
1494 /*
1495  * Execute random CPU-hotplug operations at the interval specified
1496  * by the onoff_interval.
1497  */
1498 static int __cpuinit
1499 rcu_torture_onoff(void *arg)
1500 {
1501         int cpu;
1502         unsigned long delta;
1503         int maxcpu = -1;
1504         DEFINE_RCU_RANDOM(rand);
1505         unsigned long starttime;
1506
1507         VERBOSE_PRINTK_STRING("rcu_torture_onoff task started");
1508         for_each_online_cpu(cpu)
1509                 maxcpu = cpu;
1510         WARN_ON(maxcpu < 0);
1511         if (onoff_holdoff > 0) {
1512                 VERBOSE_PRINTK_STRING("rcu_torture_onoff begin holdoff");
1513                 schedule_timeout_interruptible(onoff_holdoff * HZ);
1514                 VERBOSE_PRINTK_STRING("rcu_torture_onoff end holdoff");
1515         }
1516         while (!kthread_should_stop()) {
1517                 cpu = (rcu_random(&rand) >> 4) % (maxcpu + 1);
1518                 if (cpu_online(cpu) && cpu_is_hotpluggable(cpu)) {
1519                         if (verbose)
1520                                 pr_alert("%s" TORTURE_FLAG
1521                                          "rcu_torture_onoff task: offlining %d\n",
1522                                          torture_type, cpu);
1523                         starttime = jiffies;
1524                         n_offline_attempts++;
1525                         if (cpu_down(cpu) == 0) {
1526                                 if (verbose)
1527                                         pr_alert("%s" TORTURE_FLAG
1528                                                  "rcu_torture_onoff task: offlined %d\n",
1529                                                  torture_type, cpu);
1530                                 n_offline_successes++;
1531                                 delta = jiffies - starttime;
1532                                 sum_offline += delta;
1533                                 if (min_offline < 0) {
1534                                         min_offline = delta;
1535                                         max_offline = delta;
1536                                 }
1537                                 if (min_offline > delta)
1538                                         min_offline = delta;
1539                                 if (max_offline < delta)
1540                                         max_offline = delta;
1541                         }
1542                 } else if (cpu_is_hotpluggable(cpu)) {
1543                         if (verbose)
1544                                 pr_alert("%s" TORTURE_FLAG
1545                                          "rcu_torture_onoff task: onlining %d\n",
1546                                          torture_type, cpu);
1547                         starttime = jiffies;
1548                         n_online_attempts++;
1549                         if (cpu_up(cpu) == 0) {
1550                                 if (verbose)
1551                                         pr_alert("%s" TORTURE_FLAG
1552                                                  "rcu_torture_onoff task: onlined %d\n",
1553                                                  torture_type, cpu);
1554                                 n_online_successes++;
1555                                 delta = jiffies - starttime;
1556                                 sum_online += delta;
1557                                 if (min_online < 0) {
1558                                         min_online = delta;
1559                                         max_online = delta;
1560                                 }
1561                                 if (min_online > delta)
1562                                         min_online = delta;
1563                                 if (max_online < delta)
1564                                         max_online = delta;
1565                         }
1566                 }
1567                 schedule_timeout_interruptible(onoff_interval * HZ);
1568         }
1569         VERBOSE_PRINTK_STRING("rcu_torture_onoff task stopping");
1570         return 0;
1571 }
1572
1573 static int __cpuinit
1574 rcu_torture_onoff_init(void)
1575 {
1576         int ret;
1577
1578         if (onoff_interval <= 0)
1579                 return 0;
1580         onoff_task = kthread_run(rcu_torture_onoff, NULL, "rcu_torture_onoff");
1581         if (IS_ERR(onoff_task)) {
1582                 ret = PTR_ERR(onoff_task);
1583                 onoff_task = NULL;
1584                 return ret;
1585         }
1586         return 0;
1587 }
1588
1589 static void rcu_torture_onoff_cleanup(void)
1590 {
1591         if (onoff_task == NULL)
1592                 return;
1593         VERBOSE_PRINTK_STRING("Stopping rcu_torture_onoff task");
1594         kthread_stop(onoff_task);
1595         onoff_task = NULL;
1596 }
1597
1598 #else /* #ifdef CONFIG_HOTPLUG_CPU */
1599
1600 static int
1601 rcu_torture_onoff_init(void)
1602 {
1603         return 0;
1604 }
1605
1606 static void rcu_torture_onoff_cleanup(void)
1607 {
1608 }
1609
1610 #endif /* #else #ifdef CONFIG_HOTPLUG_CPU */
1611
1612 /*
1613  * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
1614  * induces a CPU stall for the time specified by stall_cpu.
1615  */
1616 static int __cpuinit rcu_torture_stall(void *args)
1617 {
1618         unsigned long stop_at;
1619
1620         VERBOSE_PRINTK_STRING("rcu_torture_stall task started");
1621         if (stall_cpu_holdoff > 0) {
1622                 VERBOSE_PRINTK_STRING("rcu_torture_stall begin holdoff");
1623                 schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1624                 VERBOSE_PRINTK_STRING("rcu_torture_stall end holdoff");
1625         }
1626         if (!kthread_should_stop()) {
1627                 stop_at = get_seconds() + stall_cpu;
1628                 /* RCU CPU stall is expected behavior in following code. */
1629                 pr_alert("rcu_torture_stall start.\n");
1630                 rcu_read_lock();
1631                 preempt_disable();
1632                 while (ULONG_CMP_LT(get_seconds(), stop_at))
1633                         continue;  /* Induce RCU CPU stall warning. */
1634                 preempt_enable();
1635                 rcu_read_unlock();
1636                 pr_alert("rcu_torture_stall end.\n");
1637         }
1638         rcutorture_shutdown_absorb("rcu_torture_stall");
1639         while (!kthread_should_stop())
1640                 schedule_timeout_interruptible(10 * HZ);
1641         return 0;
1642 }
1643
1644 /* Spawn CPU-stall kthread, if stall_cpu specified. */
1645 static int __init rcu_torture_stall_init(void)
1646 {
1647         int ret;
1648
1649         if (stall_cpu <= 0)
1650                 return 0;
1651         stall_task = kthread_run(rcu_torture_stall, NULL, "rcu_torture_stall");
1652         if (IS_ERR(stall_task)) {
1653                 ret = PTR_ERR(stall_task);
1654                 stall_task = NULL;
1655                 return ret;
1656         }
1657         return 0;
1658 }
1659
1660 /* Clean up after the CPU-stall kthread, if one was spawned. */
1661 static void rcu_torture_stall_cleanup(void)
1662 {
1663         if (stall_task == NULL)
1664                 return;
1665         VERBOSE_PRINTK_STRING("Stopping rcu_torture_stall_task.");
1666         kthread_stop(stall_task);
1667         stall_task = NULL;
1668 }
1669
1670 /* Callback function for RCU barrier testing. */
1671 void rcu_torture_barrier_cbf(struct rcu_head *rcu)
1672 {
1673         atomic_inc(&barrier_cbs_invoked);
1674 }
1675
1676 /* kthread function to register callbacks used to test RCU barriers. */
1677 static int rcu_torture_barrier_cbs(void *arg)
1678 {
1679         long myid = (long)arg;
1680         bool lastphase = 0;
1681         struct rcu_head rcu;
1682
1683         init_rcu_head_on_stack(&rcu);
1684         VERBOSE_PRINTK_STRING("rcu_torture_barrier_cbs task started");
1685         set_user_nice(current, 19);
1686         do {
1687                 wait_event(barrier_cbs_wq[myid],
1688                            barrier_phase != lastphase ||
1689                            kthread_should_stop() ||
1690                            fullstop != FULLSTOP_DONTSTOP);
1691                 lastphase = barrier_phase;
1692                 smp_mb(); /* ensure barrier_phase load before ->call(). */
1693                 if (kthread_should_stop() || fullstop != FULLSTOP_DONTSTOP)
1694                         break;
1695                 cur_ops->call(&rcu, rcu_torture_barrier_cbf);
1696                 if (atomic_dec_and_test(&barrier_cbs_count))
1697                         wake_up(&barrier_wq);
1698         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1699         VERBOSE_PRINTK_STRING("rcu_torture_barrier_cbs task stopping");
1700         rcutorture_shutdown_absorb("rcu_torture_barrier_cbs");
1701         while (!kthread_should_stop())
1702                 schedule_timeout_interruptible(1);
1703         cur_ops->cb_barrier();
1704         destroy_rcu_head_on_stack(&rcu);
1705         return 0;
1706 }
1707
1708 /* kthread function to drive and coordinate RCU barrier testing. */
1709 static int rcu_torture_barrier(void *arg)
1710 {
1711         int i;
1712
1713         VERBOSE_PRINTK_STRING("rcu_torture_barrier task starting");
1714         do {
1715                 atomic_set(&barrier_cbs_invoked, 0);
1716                 atomic_set(&barrier_cbs_count, n_barrier_cbs);
1717                 smp_mb(); /* Ensure barrier_phase after prior assignments. */
1718                 barrier_phase = !barrier_phase;
1719                 for (i = 0; i < n_barrier_cbs; i++)
1720                         wake_up(&barrier_cbs_wq[i]);
1721                 wait_event(barrier_wq,
1722                            atomic_read(&barrier_cbs_count) == 0 ||
1723                            kthread_should_stop() ||
1724                            fullstop != FULLSTOP_DONTSTOP);
1725                 if (kthread_should_stop() || fullstop != FULLSTOP_DONTSTOP)
1726                         break;
1727                 n_barrier_attempts++;
1728                 cur_ops->cb_barrier();
1729                 if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
1730                         n_rcu_torture_barrier_error++;
1731                         WARN_ON_ONCE(1);
1732                 }
1733                 n_barrier_successes++;
1734                 schedule_timeout_interruptible(HZ / 10);
1735         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1736         VERBOSE_PRINTK_STRING("rcu_torture_barrier task stopping");
1737         rcutorture_shutdown_absorb("rcu_torture_barrier");
1738         while (!kthread_should_stop())
1739                 schedule_timeout_interruptible(1);
1740         return 0;
1741 }
1742
1743 /* Initialize RCU barrier testing. */
1744 static int rcu_torture_barrier_init(void)
1745 {
1746         int i;
1747         int ret;
1748
1749         if (n_barrier_cbs == 0)
1750                 return 0;
1751         if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
1752                 pr_alert("%s" TORTURE_FLAG
1753                          " Call or barrier ops missing for %s,\n",
1754                          torture_type, cur_ops->name);
1755                 pr_alert("%s" TORTURE_FLAG
1756                          " RCU barrier testing omitted from run.\n",
1757                          torture_type);
1758                 return 0;
1759         }
1760         atomic_set(&barrier_cbs_count, 0);
1761         atomic_set(&barrier_cbs_invoked, 0);
1762         barrier_cbs_tasks =
1763                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_tasks[0]),
1764                         GFP_KERNEL);
1765         barrier_cbs_wq =
1766                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_wq[0]),
1767                         GFP_KERNEL);
1768         if (barrier_cbs_tasks == NULL || barrier_cbs_wq == 0)
1769                 return -ENOMEM;
1770         for (i = 0; i < n_barrier_cbs; i++) {
1771                 init_waitqueue_head(&barrier_cbs_wq[i]);
1772                 barrier_cbs_tasks[i] = kthread_run(rcu_torture_barrier_cbs,
1773                                                    (void *)(long)i,
1774                                                    "rcu_torture_barrier_cbs");
1775                 if (IS_ERR(barrier_cbs_tasks[i])) {
1776                         ret = PTR_ERR(barrier_cbs_tasks[i]);
1777                         VERBOSE_PRINTK_ERRSTRING("Failed to create rcu_torture_barrier_cbs");
1778                         barrier_cbs_tasks[i] = NULL;
1779                         return ret;
1780                 }
1781         }
1782         barrier_task = kthread_run(rcu_torture_barrier, NULL,
1783                                    "rcu_torture_barrier");
1784         if (IS_ERR(barrier_task)) {
1785                 ret = PTR_ERR(barrier_task);
1786                 VERBOSE_PRINTK_ERRSTRING("Failed to create rcu_torture_barrier");
1787                 barrier_task = NULL;
1788         }
1789         return 0;
1790 }
1791
1792 /* Clean up after RCU barrier testing. */
1793 static void rcu_torture_barrier_cleanup(void)
1794 {
1795         int i;
1796
1797         if (barrier_task != NULL) {
1798                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_barrier task");
1799                 kthread_stop(barrier_task);
1800                 barrier_task = NULL;
1801         }
1802         if (barrier_cbs_tasks != NULL) {
1803                 for (i = 0; i < n_barrier_cbs; i++) {
1804                         if (barrier_cbs_tasks[i] != NULL) {
1805                                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_barrier_cbs task");
1806                                 kthread_stop(barrier_cbs_tasks[i]);
1807                                 barrier_cbs_tasks[i] = NULL;
1808                         }
1809                 }
1810                 kfree(barrier_cbs_tasks);
1811                 barrier_cbs_tasks = NULL;
1812         }
1813         if (barrier_cbs_wq != NULL) {
1814                 kfree(barrier_cbs_wq);
1815                 barrier_cbs_wq = NULL;
1816         }
1817 }
1818
1819 static int rcutorture_cpu_notify(struct notifier_block *self,
1820                                  unsigned long action, void *hcpu)
1821 {
1822         long cpu = (long)hcpu;
1823
1824         switch (action) {
1825         case CPU_ONLINE:
1826         case CPU_DOWN_FAILED:
1827                 (void)rcutorture_booster_init(cpu);
1828                 break;
1829         case CPU_DOWN_PREPARE:
1830                 rcutorture_booster_cleanup(cpu);
1831                 break;
1832         default:
1833                 break;
1834         }
1835         return NOTIFY_OK;
1836 }
1837
1838 static struct notifier_block rcutorture_cpu_nb = {
1839         .notifier_call = rcutorture_cpu_notify,
1840 };
1841
1842 static void
1843 rcu_torture_cleanup(void)
1844 {
1845         int i;
1846
1847         mutex_lock(&fullstop_mutex);
1848         rcutorture_record_test_transition();
1849         if (fullstop == FULLSTOP_SHUTDOWN) {
1850                 pr_warn(/* but going down anyway, so... */
1851                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
1852                 mutex_unlock(&fullstop_mutex);
1853                 schedule_timeout_uninterruptible(10);
1854                 if (cur_ops->cb_barrier != NULL)
1855                         cur_ops->cb_barrier();
1856                 return;
1857         }
1858         fullstop = FULLSTOP_RMMOD;
1859         mutex_unlock(&fullstop_mutex);
1860         unregister_reboot_notifier(&rcutorture_shutdown_nb);
1861         rcu_torture_barrier_cleanup();
1862         rcu_torture_stall_cleanup();
1863         if (stutter_task) {
1864                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
1865                 kthread_stop(stutter_task);
1866         }
1867         stutter_task = NULL;
1868         if (shuffler_task) {
1869                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
1870                 kthread_stop(shuffler_task);
1871                 free_cpumask_var(shuffle_tmp_mask);
1872         }
1873         shuffler_task = NULL;
1874
1875         if (writer_task) {
1876                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
1877                 kthread_stop(writer_task);
1878         }
1879         writer_task = NULL;
1880
1881         if (reader_tasks) {
1882                 for (i = 0; i < nrealreaders; i++) {
1883                         if (reader_tasks[i]) {
1884                                 VERBOSE_PRINTK_STRING(
1885                                         "Stopping rcu_torture_reader task");
1886                                 kthread_stop(reader_tasks[i]);
1887                         }
1888                         reader_tasks[i] = NULL;
1889                 }
1890                 kfree(reader_tasks);
1891                 reader_tasks = NULL;
1892         }
1893         rcu_torture_current = NULL;
1894
1895         if (fakewriter_tasks) {
1896                 for (i = 0; i < nfakewriters; i++) {
1897                         if (fakewriter_tasks[i]) {
1898                                 VERBOSE_PRINTK_STRING(
1899                                         "Stopping rcu_torture_fakewriter task");
1900                                 kthread_stop(fakewriter_tasks[i]);
1901                         }
1902                         fakewriter_tasks[i] = NULL;
1903                 }
1904                 kfree(fakewriter_tasks);
1905                 fakewriter_tasks = NULL;
1906         }
1907
1908         if (stats_task) {
1909                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
1910                 kthread_stop(stats_task);
1911         }
1912         stats_task = NULL;
1913
1914         if (fqs_task) {
1915                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_fqs task");
1916                 kthread_stop(fqs_task);
1917         }
1918         fqs_task = NULL;
1919         if ((test_boost == 1 && cur_ops->can_boost) ||
1920             test_boost == 2) {
1921                 unregister_cpu_notifier(&rcutorture_cpu_nb);
1922                 for_each_possible_cpu(i)
1923                         rcutorture_booster_cleanup(i);
1924         }
1925         if (shutdown_task != NULL) {
1926                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shutdown task");
1927                 kthread_stop(shutdown_task);
1928         }
1929         shutdown_task = NULL;
1930         rcu_torture_onoff_cleanup();
1931
1932         /* Wait for all RCU callbacks to fire.  */
1933
1934         if (cur_ops->cb_barrier != NULL)
1935                 cur_ops->cb_barrier();
1936
1937         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1938
1939         if (cur_ops->cleanup)
1940                 cur_ops->cleanup();
1941         if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
1942                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1943         else if (n_online_successes != n_online_attempts ||
1944                  n_offline_successes != n_offline_attempts)
1945                 rcu_torture_print_module_parms(cur_ops,
1946                                                "End of test: RCU_HOTPLUG");
1947         else
1948                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1949 }
1950
1951 static int __init
1952 rcu_torture_init(void)
1953 {
1954         int i;
1955         int cpu;
1956         int firsterr = 0;
1957         int retval;
1958         static struct rcu_torture_ops *torture_ops[] =
1959                 { &rcu_ops, &rcu_sync_ops, &rcu_expedited_ops,
1960                   &rcu_bh_ops, &rcu_bh_sync_ops, &rcu_bh_expedited_ops,
1961                   &srcu_ops, &srcu_sync_ops, &srcu_expedited_ops,
1962                   &srcu_raw_ops, &srcu_raw_sync_ops,
1963                   &sched_ops, &sched_sync_ops, &sched_expedited_ops, };
1964
1965         mutex_lock(&fullstop_mutex);
1966
1967         /* Process args and tell the world that the torturer is on the job. */
1968         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1969                 cur_ops = torture_ops[i];
1970                 if (strcmp(torture_type, cur_ops->name) == 0)
1971                         break;
1972         }
1973         if (i == ARRAY_SIZE(torture_ops)) {
1974                 pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
1975                          torture_type);
1976                 pr_alert("rcu-torture types:");
1977                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1978                         pr_alert(" %s", torture_ops[i]->name);
1979                 pr_alert("\n");
1980                 mutex_unlock(&fullstop_mutex);
1981                 return -EINVAL;
1982         }
1983         if (cur_ops->fqs == NULL && fqs_duration != 0) {
1984                 pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
1985                 fqs_duration = 0;
1986         }
1987         if (cur_ops->init)
1988                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1989
1990         if (nreaders >= 0)
1991                 nrealreaders = nreaders;
1992         else
1993                 nrealreaders = 2 * num_online_cpus();
1994         rcu_torture_print_module_parms(cur_ops, "Start of test");
1995         fullstop = FULLSTOP_DONTSTOP;
1996
1997         /* Set up the freelist. */
1998
1999         INIT_LIST_HEAD(&rcu_torture_freelist);
2000         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
2001                 rcu_tortures[i].rtort_mbtest = 0;
2002                 list_add_tail(&rcu_tortures[i].rtort_free,
2003                               &rcu_torture_freelist);
2004         }
2005
2006         /* Initialize the statistics so that each run gets its own numbers. */
2007
2008         rcu_torture_current = NULL;
2009         rcu_torture_current_version = 0;
2010         atomic_set(&n_rcu_torture_alloc, 0);
2011         atomic_set(&n_rcu_torture_alloc_fail, 0);
2012         atomic_set(&n_rcu_torture_free, 0);
2013         atomic_set(&n_rcu_torture_mberror, 0);
2014         atomic_set(&n_rcu_torture_error, 0);
2015         n_rcu_torture_barrier_error = 0;
2016         n_rcu_torture_boost_ktrerror = 0;
2017         n_rcu_torture_boost_rterror = 0;
2018         n_rcu_torture_boost_failure = 0;
2019         n_rcu_torture_boosts = 0;
2020         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
2021                 atomic_set(&rcu_torture_wcount[i], 0);
2022         for_each_possible_cpu(cpu) {
2023                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
2024                         per_cpu(rcu_torture_count, cpu)[i] = 0;
2025                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
2026                 }
2027         }
2028
2029         /* Start up the kthreads. */
2030
2031         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
2032         writer_task = kthread_create(rcu_torture_writer, NULL,
2033                                      "rcu_torture_writer");
2034         if (IS_ERR(writer_task)) {
2035                 firsterr = PTR_ERR(writer_task);
2036                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
2037                 writer_task = NULL;
2038                 goto unwind;
2039         }
2040         wake_up_process(writer_task);
2041         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
2042                                    GFP_KERNEL);
2043         if (fakewriter_tasks == NULL) {
2044                 VERBOSE_PRINTK_ERRSTRING("out of memory");
2045                 firsterr = -ENOMEM;
2046                 goto unwind;
2047         }
2048         for (i = 0; i < nfakewriters; i++) {
2049                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
2050                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
2051                                                   "rcu_torture_fakewriter");
2052                 if (IS_ERR(fakewriter_tasks[i])) {
2053                         firsterr = PTR_ERR(fakewriter_tasks[i]);
2054                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
2055                         fakewriter_tasks[i] = NULL;
2056                         goto unwind;
2057                 }
2058         }
2059         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
2060                                GFP_KERNEL);
2061         if (reader_tasks == NULL) {
2062                 VERBOSE_PRINTK_ERRSTRING("out of memory");
2063                 firsterr = -ENOMEM;
2064                 goto unwind;
2065         }
2066         for (i = 0; i < nrealreaders; i++) {
2067                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
2068                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
2069                                               "rcu_torture_reader");
2070                 if (IS_ERR(reader_tasks[i])) {
2071                         firsterr = PTR_ERR(reader_tasks[i]);
2072                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
2073                         reader_tasks[i] = NULL;
2074                         goto unwind;
2075                 }
2076         }
2077         if (stat_interval > 0) {
2078                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
2079                 stats_task = kthread_run(rcu_torture_stats, NULL,
2080                                         "rcu_torture_stats");
2081                 if (IS_ERR(stats_task)) {
2082                         firsterr = PTR_ERR(stats_task);
2083                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
2084                         stats_task = NULL;
2085                         goto unwind;
2086                 }
2087         }
2088         if (test_no_idle_hz) {
2089                 rcu_idle_cpu = num_online_cpus() - 1;
2090
2091                 if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
2092                         firsterr = -ENOMEM;
2093                         VERBOSE_PRINTK_ERRSTRING("Failed to alloc mask");
2094                         goto unwind;
2095                 }
2096
2097                 /* Create the shuffler thread */
2098                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
2099                                           "rcu_torture_shuffle");
2100                 if (IS_ERR(shuffler_task)) {
2101                         free_cpumask_var(shuffle_tmp_mask);
2102                         firsterr = PTR_ERR(shuffler_task);
2103                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
2104                         shuffler_task = NULL;
2105                         goto unwind;
2106                 }
2107         }
2108         if (stutter < 0)
2109                 stutter = 0;
2110         if (stutter) {
2111                 /* Create the stutter thread */
2112                 stutter_task = kthread_run(rcu_torture_stutter, NULL,
2113                                           "rcu_torture_stutter");
2114                 if (IS_ERR(stutter_task)) {
2115                         firsterr = PTR_ERR(stutter_task);
2116                         VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
2117                         stutter_task = NULL;
2118                         goto unwind;
2119                 }
2120         }
2121         if (fqs_duration < 0)
2122                 fqs_duration = 0;
2123         if (fqs_duration) {
2124                 /* Create the stutter thread */
2125                 fqs_task = kthread_run(rcu_torture_fqs, NULL,
2126                                        "rcu_torture_fqs");
2127                 if (IS_ERR(fqs_task)) {
2128                         firsterr = PTR_ERR(fqs_task);
2129                         VERBOSE_PRINTK_ERRSTRING("Failed to create fqs");
2130                         fqs_task = NULL;
2131                         goto unwind;
2132                 }
2133         }
2134         if (test_boost_interval < 1)
2135                 test_boost_interval = 1;
2136         if (test_boost_duration < 2)
2137                 test_boost_duration = 2;
2138         if ((test_boost == 1 && cur_ops->can_boost) ||
2139             test_boost == 2) {
2140
2141                 boost_starttime = jiffies + test_boost_interval * HZ;
2142                 register_cpu_notifier(&rcutorture_cpu_nb);
2143                 for_each_possible_cpu(i) {
2144                         if (cpu_is_offline(i))
2145                                 continue;  /* Heuristic: CPU can go offline. */
2146                         retval = rcutorture_booster_init(i);
2147                         if (retval < 0) {
2148                                 firsterr = retval;
2149                                 goto unwind;
2150                         }
2151                 }
2152         }
2153         if (shutdown_secs > 0) {
2154                 shutdown_time = jiffies + shutdown_secs * HZ;
2155                 shutdown_task = kthread_create(rcu_torture_shutdown, NULL,
2156                                                "rcu_torture_shutdown");
2157                 if (IS_ERR(shutdown_task)) {
2158                         firsterr = PTR_ERR(shutdown_task);
2159                         VERBOSE_PRINTK_ERRSTRING("Failed to create shutdown");
2160                         shutdown_task = NULL;
2161                         goto unwind;
2162                 }
2163                 wake_up_process(shutdown_task);
2164         }
2165         i = rcu_torture_onoff_init();
2166         if (i != 0) {
2167                 firsterr = i;
2168                 goto unwind;
2169         }
2170         register_reboot_notifier(&rcutorture_shutdown_nb);
2171         i = rcu_torture_stall_init();
2172         if (i != 0) {
2173                 firsterr = i;
2174                 goto unwind;
2175         }
2176         retval = rcu_torture_barrier_init();
2177         if (retval != 0) {
2178                 firsterr = retval;
2179                 goto unwind;
2180         }
2181         rcutorture_record_test_transition();
2182         mutex_unlock(&fullstop_mutex);
2183         return 0;
2184
2185 unwind:
2186         mutex_unlock(&fullstop_mutex);
2187         rcu_torture_cleanup();
2188         return firsterr;
2189 }
2190
2191 module_init(rcu_torture_init);
2192 module_exit(rcu_torture_cleanup);