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 <linux/trace_clock.h>
  50 #include <asm/byteorder.h>
  51
  52 MODULE_LICENSE("GPL");
  53 MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and Josh Triplett <josh@freedesktop.org>");
  54
  55 static int nreaders = -1;       /* # reader threads, defaults to 2*ncpus */
  56 static int nfakewriters = 4;    /* # fake writer threads */
  57 static int stat_interval = 60;  /* Interval between stats, in seconds. */
  58                                 /*  Zero means "only at end of test". */
  59 static bool verbose;            /* Print more debug info. */
  60 static bool test_no_idle_hz = true;
  61                                 /* Test RCU support for tickless idle CPUs. */
  62 static int shuffle_interval = 3; /* Interval between shuffles (in sec)*/
  63 static int stutter = 5;         /* Start/stop testing interval (in sec) */
  64 static int irqreader = 1;       /* RCU readers from irq (timers). */
  65 static int fqs_duration;        /* Duration of bursts (us), 0 to disable. */
  66 static int fqs_holdoff;         /* Hold time within burst (us). */
  67 static int fqs_stutter = 3;     /* Wait time between bursts (s). */
  68 static int n_barrier_cbs;       /* Number of callbacks to test RCU barriers. */
  69 static int onoff_interval;      /* Wait time between CPU hotplugs, 0=disable. */
  70 static int onoff_holdoff;       /* Seconds after boot before CPU hotplugs. */
  71 static int shutdown_secs;       /* Shutdown time (s).  <=0 for no shutdown. */
  72 static int stall_cpu;           /* CPU-stall duration (s).  0 for no stall. */
  73 static int stall_cpu_holdoff = 10; /* Time to wait until stall (s).  */
  74 static int test_boost = 1;      /* Test RCU prio boost: 0=no, 1=maybe, 2=yes. */
  75 static int test_boost_interval = 7; /* Interval between boost tests, seconds. */
  76 static int test_boost_duration = 4; /* Duration of each boost test, seconds. */
  77 static char *torture_type = "rcu"; /* What RCU implementation to torture. */
  78
  79 module_param(nreaders, int, 0444);
  80 MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
  81 module_param(nfakewriters, int, 0444);
  82 MODULE_PARM_DESC(nfakewriters, "Number of RCU fake writer threads");
  83 module_param(stat_interval, int, 0644);
  84 MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
  85 module_param(verbose, bool, 0444);
  86 MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
  87 module_param(test_no_idle_hz, bool, 0444);
  88 MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
  89 module_param(shuffle_interval, int, 0444);
  90 MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
  91 module_param(stutter, int, 0444);
  92 MODULE_PARM_DESC(stutter, "Number of seconds to run/halt test");
  93 module_param(irqreader, int, 0444);
  94 MODULE_PARM_DESC(irqreader, "Allow RCU readers from irq handlers");
  95 module_param(fqs_duration, int, 0444);
  96 MODULE_PARM_DESC(fqs_duration, "Duration of fqs bursts (us)");
  97 module_param(fqs_holdoff, int, 0444);
  98 MODULE_PARM_DESC(fqs_holdoff, "Holdoff time within fqs bursts (us)");
  99 module_param(fqs_stutter, int, 0444);
 100 MODULE_PARM_DESC(fqs_stutter, "Wait time between fqs bursts (s)");
 101 module_param(n_barrier_cbs, int, 0444);
 102 MODULE_PARM_DESC(n_barrier_cbs, "# of callbacks/kthreads for barrier testing");
 103 module_param(onoff_interval, int, 0444);
 104 MODULE_PARM_DESC(onoff_interval, "Time between CPU hotplugs (s), 0=disable");
 105 module_param(onoff_holdoff, int, 0444);
 106 MODULE_PARM_DESC(onoff_holdoff, "Time after boot before CPU hotplugs (s)");
 107 module_param(shutdown_secs, int, 0444);
 108 MODULE_PARM_DESC(shutdown_secs, "Shutdown time (s), zero to disable.");
 109 module_param(stall_cpu, int, 0444);
 110 MODULE_PARM_DESC(stall_cpu, "Stall duration (s), zero to disable.");
 111 module_param(stall_cpu_holdoff, int, 0444);
 112 MODULE_PARM_DESC(stall_cpu_holdoff, "Time to wait before starting stall (s).");
 113 module_param(test_boost, int, 0444);
 114 MODULE_PARM_DESC(test_boost, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
 115 module_param(test_boost_interval, int, 0444);
 116 MODULE_PARM_DESC(test_boost_interval, "Interval between boost tests, seconds.");
 117 module_param(test_boost_duration, int, 0444);
 118 MODULE_PARM_DESC(test_boost_duration, "Duration of each boost test, seconds.");
 119 module_param(torture_type, charp, 0444);
 120 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, srcu)");
 121
 122 #define TORTURE_FLAG "-torture:"
 123 #define PRINTK_STRING(s) \
 124         do { pr_alert("%s" TORTURE_FLAG s "\n", torture_type); } while (0)
 125 #define VERBOSE_PRINTK_STRING(s) \
 126         do { if (verbose) pr_alert("%s" TORTURE_FLAG s "\n", torture_type); } while (0)
 127 #define VERBOSE_PRINTK_ERRSTRING(s) \
 128         do { if (verbose) pr_alert("%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
 129
 130 static char printk_buf[4096];
 131
 132 static int nrealreaders;
 133 static struct task_struct *writer_task;
 134 static struct task_struct **fakewriter_tasks;
 135 static struct task_struct **reader_tasks;
 136 static struct task_struct *stats_task;
 137 static struct task_struct *shuffler_task;
 138 static struct task_struct *stutter_task;
 139 static struct task_struct *fqs_task;
 140 static struct task_struct *boost_tasks[NR_CPUS];
 141 static struct task_struct *shutdown_task;
 142 #ifdef CONFIG_HOTPLUG_CPU
 143 static struct task_struct *onoff_task;
 144 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
 145 static struct task_struct *stall_task;
 146 static struct task_struct **barrier_cbs_tasks;
 147 static struct task_struct *barrier_task;
 148
 149 #define RCU_TORTURE_PIPE_LEN 10
 150
 151 struct rcu_torture {
 152         struct rcu_head rtort_rcu;
 153         int rtort_pipe_count;
 154         struct list_head rtort_free;
 155         int rtort_mbtest;
 156 };
 157
 158 static LIST_HEAD(rcu_torture_freelist);
 159 static struct rcu_torture __rcu *rcu_torture_current;
 160 static unsigned long rcu_torture_current_version;
 161 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 162 static DEFINE_SPINLOCK(rcu_torture_lock);
 163 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
 164         { 0 };
 165 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) =
 166         { 0 };
 167 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 168 static atomic_t n_rcu_torture_alloc;
 169 static atomic_t n_rcu_torture_alloc_fail;
 170 static atomic_t n_rcu_torture_free;
 171 static atomic_t n_rcu_torture_mberror;
 172 static atomic_t n_rcu_torture_error;
 173 static long n_rcu_torture_barrier_error;
 174 static long n_rcu_torture_boost_ktrerror;
 175 static long n_rcu_torture_boost_rterror;
 176 static long n_rcu_torture_boost_failure;
 177 static long n_rcu_torture_boosts;
 178 static long n_rcu_torture_timers;
 179 static long n_offline_attempts;
 180 static long n_offline_successes;
 181 static unsigned long sum_offline;
 182 static int min_offline = -1;
 183 static int max_offline;
 184 static long n_online_attempts;
 185 static long n_online_successes;
 186 static unsigned long sum_online;
 187 static int min_online = -1;
 188 static int max_online;
 189 static long n_barrier_attempts;
 190 static long n_barrier_successes;
 191 static struct list_head rcu_torture_removed;
 192 static cpumask_var_t shuffle_tmp_mask;
 193
 194 static int stutter_pause_test;
 195
 196 #if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
 197 #define RCUTORTURE_RUNNABLE_INIT 1
 198 #else
 199 #define RCUTORTURE_RUNNABLE_INIT 0
 200 #endif
 201 int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT;
 202 module_param(rcutorture_runnable, int, 0444);
 203 MODULE_PARM_DESC(rcutorture_runnable, "Start rcutorture at boot");
 204
 205 #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
 206 #define rcu_can_boost() 1
 207 #else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 208 #define rcu_can_boost() 0
 209 #endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 210
 211 #ifdef CONFIG_RCU_TRACE
 212 static u64 notrace rcu_trace_clock_local(void)
 213 {
 214         u64 ts = trace_clock_local();
 215         unsigned long __maybe_unused ts_rem = do_div(ts, NSEC_PER_USEC);
 216         return ts;
 217 }
 218 #else /* #ifdef CONFIG_RCU_TRACE */
 219 static u64 notrace rcu_trace_clock_local(void)
 220 {
 221         return 0ULL;
 222 }
 223 #endif /* #else #ifdef CONFIG_RCU_TRACE */
 224
 225 static unsigned long shutdown_time;     /* jiffies to system shutdown. */
 226 static unsigned long boost_starttime;   /* jiffies of next boost test start. */
 227 DEFINE_MUTEX(boost_mutex);              /* protect setting boost_starttime */
 228                                         /*  and boost task create/destroy. */
 229 static atomic_t barrier_cbs_count;      /* Barrier callbacks registered. */
 230 static bool barrier_phase;              /* Test phase. */
 231 static atomic_t barrier_cbs_invoked;    /* Barrier callbacks invoked. */
 232 static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */
 233 static DECLARE_WAIT_QUEUE_HEAD(barrier_wq);
 234
 235 /* Mediate rmmod and system shutdown.  Concurrent rmmod & shutdown illegal! */
 236
 237 #define FULLSTOP_DONTSTOP 0     /* Normal operation. */
 238 #define FULLSTOP_SHUTDOWN 1     /* System shutdown with rcutorture running. */
 239 #define FULLSTOP_RMMOD    2     /* Normal rmmod of rcutorture. */
 240 static int fullstop = FULLSTOP_RMMOD;
 241 /*
 242  * Protect fullstop transitions and spawning of kthreads.
 243  */
 244 static DEFINE_MUTEX(fullstop_mutex);
 245
 246 /* Forward reference. */
 247 static void rcu_torture_cleanup(void);
 248
 249 /*
 250  * Detect and respond to a system shutdown.
 251  */
 252 static int
 253 rcutorture_shutdown_notify(struct notifier_block *unused1,
 254                            unsigned long unused2, void *unused3)
 255 {
 256         mutex_lock(&fullstop_mutex);
 257         if (fullstop == FULLSTOP_DONTSTOP)
 258                 fullstop = FULLSTOP_SHUTDOWN;
 259         else
 260                 pr_warn(/* but going down anyway, so... */
 261                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
 262         mutex_unlock(&fullstop_mutex);
 263         return NOTIFY_DONE;
 264 }
 265
 266 /*
 267  * Absorb kthreads into a kernel function that won't return, so that
 268  * they won't ever access module text or data again.
 269  */
 270 static void rcutorture_shutdown_absorb(char *title)
 271 {
 272         if (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
 273                 pr_notice(
 274                        "rcutorture thread %s parking due to system shutdown\n",
 275                        title);
 276                 schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
 277         }
 278 }
 279
 280 /*
 281  * Allocate an element from the rcu_tortures pool.
 282  */
 283 static struct rcu_torture *
 284 rcu_torture_alloc(void)
 285 {
 286         struct list_head *p;
 287
 288         spin_lock_bh(&rcu_torture_lock);
 289         if (list_empty(&rcu_torture_freelist)) {
 290                 atomic_inc(&n_rcu_torture_alloc_fail);
 291                 spin_unlock_bh(&rcu_torture_lock);
 292                 return NULL;
 293         }
 294         atomic_inc(&n_rcu_torture_alloc);
 295         p = rcu_torture_freelist.next;
 296         list_del_init(p);
 297         spin_unlock_bh(&rcu_torture_lock);
 298         return container_of(p, struct rcu_torture, rtort_free);
 299 }
 300
 301 /*
 302  * Free an element to the rcu_tortures pool.
 303  */
 304 static void
 305 rcu_torture_free(struct rcu_torture *p)
 306 {
 307         atomic_inc(&n_rcu_torture_free);
 308         spin_lock_bh(&rcu_torture_lock);
 309         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 310         spin_unlock_bh(&rcu_torture_lock);
 311 }
 312
 313 struct rcu_random_state {
 314         unsigned long rrs_state;
 315         long rrs_count;
 316 };
 317
 318 #define RCU_RANDOM_MULT 39916801  /* prime */
 319 #define RCU_RANDOM_ADD  479001701 /* prime */
 320 #define RCU_RANDOM_REFRESH 10000
 321
 322 #define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
 323
 324 /*
 325  * Crude but fast random-number generator.  Uses a linear congruential
 326  * generator, with occasional help from cpu_clock().
 327  */
 328 static unsigned long
 329 rcu_random(struct rcu_random_state *rrsp)
 330 {
 331         if (--rrsp->rrs_count < 0) {
 332                 rrsp->rrs_state += (unsigned long)local_clock();
 333                 rrsp->rrs_count = RCU_RANDOM_REFRESH;
 334         }
 335         rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
 336         return swahw32(rrsp->rrs_state);
 337 }
 338
 339 static void
 340 rcu_stutter_wait(char *title)
 341 {
 342         while (stutter_pause_test || !rcutorture_runnable) {
 343                 if (rcutorture_runnable)
 344                         schedule_timeout_interruptible(1);
 345                 else
 346                         schedule_timeout_interruptible(round_jiffies_relative(HZ));
 347                 rcutorture_shutdown_absorb(title);
 348         }
 349 }
 350
 351 /*
 352  * Operations vector for selecting different types of tests.
 353  */
 354
 355 struct rcu_torture_ops {
 356         void (*init)(void);
 357         int (*readlock)(void);
 358         void (*read_delay)(struct rcu_random_state *rrsp);
 359         void (*readunlock)(int idx);
 360         int (*completed)(void);
 361         void (*deferred_free)(struct rcu_torture *p);
 362         void (*sync)(void);
 363         void (*call)(struct rcu_head *head, void (*func)(struct rcu_head *rcu));
 364         void (*cb_barrier)(void);
 365         void (*fqs)(void);
 366         int (*stats)(char *page);
 367         int irq_capable;
 368         int can_boost;
 369         char *name;
 370 };
 371
 372 static struct rcu_torture_ops *cur_ops;
 373
 374 /*
 375  * Definitions for rcu torture testing.
 376  */
 377
 378 static int rcu_torture_read_lock(void) __acquires(RCU)
 379 {
 380         rcu_read_lock();
 381         return 0;
 382 }
 383
 384 static void rcu_read_delay(struct rcu_random_state *rrsp)
 385 {
 386         const unsigned long shortdelay_us = 200;
 387         const unsigned long longdelay_ms = 50;
 388
 389         /* We want a short delay sometimes to make a reader delay the grace
 390          * period, and we want a long delay occasionally to trigger
 391          * force_quiescent_state. */
 392
 393         if (!(rcu_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
 394                 mdelay(longdelay_ms);
 395         if (!(rcu_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
 396                 udelay(shortdelay_us);
 397 #ifdef CONFIG_PREEMPT
 398         if (!preempt_count() && !(rcu_random(rrsp) % (nrealreaders * 20000)))
 399                 preempt_schedule();  /* No QS if preempt_disable() in effect */
 400 #endif
 401 }
 402
 403 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 404 {
 405         rcu_read_unlock();
 406 }
 407
 408 static int rcu_torture_completed(void)
 409 {
 410         return rcu_batches_completed();
 411 }
 412
 413 static void
 414 rcu_torture_cb(struct rcu_head *p)
 415 {
 416         int i;
 417         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 418
 419         if (fullstop != FULLSTOP_DONTSTOP) {
 420                 /* Test is ending, just drop callbacks on the floor. */
 421                 /* The next initialization will pick up the pieces. */
 422                 return;
 423         }
 424         i = rp->rtort_pipe_count;
 425         if (i > RCU_TORTURE_PIPE_LEN)
 426                 i = RCU_TORTURE_PIPE_LEN;
 427         atomic_inc(&rcu_torture_wcount[i]);
 428         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 429                 rp->rtort_mbtest = 0;
 430                 rcu_torture_free(rp);
 431         } else {
 432                 cur_ops->deferred_free(rp);
 433         }
 434 }
 435
 436 static int rcu_no_completed(void)
 437 {
 438         return 0;
 439 }
 440
 441 static void rcu_torture_deferred_free(struct rcu_torture *p)
 442 {
 443         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 444 }
 445
 446 static struct rcu_torture_ops rcu_ops = {
 447         .init           = NULL,
 448         .readlock       = rcu_torture_read_lock,
 449         .read_delay     = rcu_read_delay,
 450         .readunlock     = rcu_torture_read_unlock,
 451         .completed      = rcu_torture_completed,
 452         .deferred_free  = rcu_torture_deferred_free,
 453         .sync           = synchronize_rcu,
 454         .call           = call_rcu,
 455         .cb_barrier     = rcu_barrier,
 456         .fqs            = rcu_force_quiescent_state,
 457         .stats          = NULL,
 458         .irq_capable    = 1,
 459         .can_boost      = rcu_can_boost(),
 460         .name           = "rcu"
 461 };
 462
 463 static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
 464 {
 465         int i;
 466         struct rcu_torture *rp;
 467         struct rcu_torture *rp1;
 468
 469         cur_ops->sync();
 470         list_add(&p->rtort_free, &rcu_torture_removed);
 471         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 472                 i = rp->rtort_pipe_count;
 473                 if (i > RCU_TORTURE_PIPE_LEN)
 474                         i = RCU_TORTURE_PIPE_LEN;
 475                 atomic_inc(&rcu_torture_wcount[i]);
 476                 if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 477                         rp->rtort_mbtest = 0;
 478                         list_del(&rp->rtort_free);
 479                         rcu_torture_free(rp);
 480                 }
 481         }
 482 }
 483
 484 static void rcu_sync_torture_init(void)
 485 {
 486         INIT_LIST_HEAD(&rcu_torture_removed);
 487 }
 488
 489 static struct rcu_torture_ops rcu_sync_ops = {
 490         .init           = rcu_sync_torture_init,
 491         .readlock       = rcu_torture_read_lock,
 492         .read_delay     = rcu_read_delay,
 493         .readunlock     = rcu_torture_read_unlock,
 494         .completed      = rcu_torture_completed,
 495         .deferred_free  = rcu_sync_torture_deferred_free,
 496         .sync           = synchronize_rcu,
 497         .call           = NULL,
 498         .cb_barrier     = NULL,
 499         .fqs            = rcu_force_quiescent_state,
 500         .stats          = NULL,
 501         .irq_capable    = 1,
 502         .can_boost      = rcu_can_boost(),
 503         .name           = "rcu_sync"
 504 };
 505
 506 static struct rcu_torture_ops rcu_expedited_ops = {
 507         .init           = rcu_sync_torture_init,
 508         .readlock       = rcu_torture_read_lock,
 509         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 510         .readunlock     = rcu_torture_read_unlock,
 511         .completed      = rcu_no_completed,
 512         .deferred_free  = rcu_sync_torture_deferred_free,
 513         .sync           = synchronize_rcu_expedited,
 514         .call           = NULL,
 515         .cb_barrier     = NULL,
 516         .fqs            = rcu_force_quiescent_state,
 517         .stats          = NULL,
 518         .irq_capable    = 1,
 519         .can_boost      = rcu_can_boost(),
 520         .name           = "rcu_expedited"
 521 };
 522
 523 /*
 524  * Definitions for rcu_bh torture testing.
 525  */
 526
 527 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
 528 {
 529         rcu_read_lock_bh();
 530         return 0;
 531 }
 532
 533 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
 534 {
 535         rcu_read_unlock_bh();
 536 }
 537
 538 static int rcu_bh_torture_completed(void)
 539 {
 540         return rcu_batches_completed_bh();
 541 }
 542
 543 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 544 {
 545         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
 546 }
 547
 548 static struct rcu_torture_ops rcu_bh_ops = {
 549         .init           = NULL,
 550         .readlock       = rcu_bh_torture_read_lock,
 551         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 552         .readunlock     = rcu_bh_torture_read_unlock,
 553         .completed      = rcu_bh_torture_completed,
 554         .deferred_free  = rcu_bh_torture_deferred_free,
 555         .sync           = synchronize_rcu_bh,
 556         .call           = call_rcu_bh,
 557         .cb_barrier     = rcu_barrier_bh,
 558         .fqs            = rcu_bh_force_quiescent_state,
 559         .stats          = NULL,
 560         .irq_capable    = 1,
 561         .name           = "rcu_bh"
 562 };
 563
 564 static struct rcu_torture_ops rcu_bh_sync_ops = {
 565         .init           = rcu_sync_torture_init,
 566         .readlock       = rcu_bh_torture_read_lock,
 567         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 568         .readunlock     = rcu_bh_torture_read_unlock,
 569         .completed      = rcu_bh_torture_completed,
 570         .deferred_free  = rcu_sync_torture_deferred_free,
 571         .sync           = synchronize_rcu_bh,
 572         .call           = NULL,
 573         .cb_barrier     = NULL,
 574         .fqs            = rcu_bh_force_quiescent_state,
 575         .stats          = NULL,
 576         .irq_capable    = 1,
 577         .name           = "rcu_bh_sync"
 578 };
 579
 580 static struct rcu_torture_ops rcu_bh_expedited_ops = {
 581         .init           = rcu_sync_torture_init,
 582         .readlock       = rcu_bh_torture_read_lock,
 583         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 584         .readunlock     = rcu_bh_torture_read_unlock,
 585         .completed      = rcu_bh_torture_completed,
 586         .deferred_free  = rcu_sync_torture_deferred_free,
 587         .sync           = synchronize_rcu_bh_expedited,
 588         .call           = NULL,
 589         .cb_barrier     = NULL,
 590         .fqs            = rcu_bh_force_quiescent_state,
 591         .stats          = NULL,
 592         .irq_capable    = 1,
 593         .name           = "rcu_bh_expedited"
 594 };
 595
 596 /*
 597  * Definitions for srcu torture testing.
 598  */
 599
 600 DEFINE_STATIC_SRCU(srcu_ctl);
 601
 602 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
 603 {
 604         return srcu_read_lock(&srcu_ctl);
 605 }
 606
 607 static void srcu_read_delay(struct rcu_random_state *rrsp)
 608 {
 609         long delay;
 610         const long uspertick = 1000000 / HZ;
 611         const long longdelay = 10;
 612
 613         /* We want there to be long-running readers, but not all the time. */
 614
 615         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
 616         if (!delay)
 617                 schedule_timeout_interruptible(longdelay);
 618         else
 619                 rcu_read_delay(rrsp);
 620 }
 621
 622 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
 623 {
 624         srcu_read_unlock(&srcu_ctl, idx);
 625 }
 626
 627 static int srcu_torture_completed(void)
 628 {
 629         return srcu_batches_completed(&srcu_ctl);
 630 }
 631
 632 static void srcu_torture_deferred_free(struct rcu_torture *rp)
 633 {
 634         call_srcu(&srcu_ctl, &rp->rtort_rcu, rcu_torture_cb);
 635 }
 636
 637 static void srcu_torture_synchronize(void)
 638 {
 639         synchronize_srcu(&srcu_ctl);
 640 }
 641
 642 static void srcu_torture_call(struct rcu_head *head,
 643                               void (*func)(struct rcu_head *head))
 644 {
 645         call_srcu(&srcu_ctl, head, func);
 646 }
 647
 648 static void srcu_torture_barrier(void)
 649 {
 650         srcu_barrier(&srcu_ctl);
 651 }
 652
 653 static int srcu_torture_stats(char *page)
 654 {
 655         int cnt = 0;
 656         int cpu;
 657         int idx = srcu_ctl.completed & 0x1;
 658
 659         cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
 660                        torture_type, TORTURE_FLAG, idx);
 661         for_each_possible_cpu(cpu) {
 662                 cnt += sprintf(&page[cnt], " %d(%lu,%lu)", cpu,
 663                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
 664                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
 665         }
 666         cnt += sprintf(&page[cnt], "\n");
 667         return cnt;
 668 }
 669
 670 static struct rcu_torture_ops srcu_ops = {
 671         .init           = rcu_sync_torture_init,
 672         .readlock       = srcu_torture_read_lock,
 673         .read_delay     = srcu_read_delay,
 674         .readunlock     = srcu_torture_read_unlock,
 675         .completed      = srcu_torture_completed,
 676         .deferred_free  = srcu_torture_deferred_free,
 677         .sync           = srcu_torture_synchronize,
 678         .call           = srcu_torture_call,
 679         .cb_barrier     = srcu_torture_barrier,
 680         .stats          = srcu_torture_stats,
 681         .name           = "srcu"
 682 };
 683
 684 static struct rcu_torture_ops srcu_sync_ops = {
 685         .init           = rcu_sync_torture_init,
 686         .readlock       = srcu_torture_read_lock,
 687         .read_delay     = srcu_read_delay,
 688         .readunlock     = srcu_torture_read_unlock,
 689         .completed      = srcu_torture_completed,
 690         .deferred_free  = rcu_sync_torture_deferred_free,
 691         .sync           = srcu_torture_synchronize,
 692         .call           = NULL,
 693         .cb_barrier     = NULL,
 694         .stats          = srcu_torture_stats,
 695         .name           = "srcu_sync"
 696 };
 697
 698 static void srcu_torture_synchronize_expedited(void)
 699 {
 700         synchronize_srcu_expedited(&srcu_ctl);
 701 }
 702
 703 static struct rcu_torture_ops srcu_expedited_ops = {
 704         .init           = rcu_sync_torture_init,
 705         .readlock       = srcu_torture_read_lock,
 706         .read_delay     = srcu_read_delay,
 707         .readunlock     = srcu_torture_read_unlock,
 708         .completed      = srcu_torture_completed,
 709         .deferred_free  = rcu_sync_torture_deferred_free,
 710         .sync           = srcu_torture_synchronize_expedited,
 711         .call           = NULL,
 712         .cb_barrier     = NULL,
 713         .stats          = srcu_torture_stats,
 714         .name           = "srcu_expedited"
 715 };
 716
 717 /*
 718  * Definitions for sched torture testing.
 719  */
 720
 721 static int sched_torture_read_lock(void)
 722 {
 723         preempt_disable();
 724         return 0;
 725 }
 726
 727 static void sched_torture_read_unlock(int idx)
 728 {
 729         preempt_enable();
 730 }
 731
 732 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
 733 {
 734         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
 735 }
 736
 737 static struct rcu_torture_ops sched_ops = {
 738         .init           = rcu_sync_torture_init,
 739         .readlock       = sched_torture_read_lock,
 740         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 741         .readunlock     = sched_torture_read_unlock,
 742         .completed      = rcu_no_completed,
 743         .deferred_free  = rcu_sched_torture_deferred_free,
 744         .sync           = synchronize_sched,
 745         .cb_barrier     = rcu_barrier_sched,
 746         .fqs            = rcu_sched_force_quiescent_state,
 747         .stats          = NULL,
 748         .irq_capable    = 1,
 749         .name           = "sched"
 750 };
 751
 752 static struct rcu_torture_ops sched_sync_ops = {
 753         .init           = rcu_sync_torture_init,
 754         .readlock       = sched_torture_read_lock,
 755         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 756         .readunlock     = sched_torture_read_unlock,
 757         .completed      = rcu_no_completed,
 758         .deferred_free  = rcu_sync_torture_deferred_free,
 759         .sync           = synchronize_sched,
 760         .cb_barrier     = NULL,
 761         .fqs            = rcu_sched_force_quiescent_state,
 762         .stats          = NULL,
 763         .name           = "sched_sync"
 764 };
 765
 766 static struct rcu_torture_ops sched_expedited_ops = {
 767         .init           = rcu_sync_torture_init,
 768         .readlock       = sched_torture_read_lock,
 769         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 770         .readunlock     = sched_torture_read_unlock,
 771         .completed      = rcu_no_completed,
 772         .deferred_free  = rcu_sync_torture_deferred_free,
 773         .sync           = synchronize_sched_expedited,
 774         .cb_barrier     = NULL,
 775         .fqs            = rcu_sched_force_quiescent_state,
 776         .stats          = NULL,
 777         .irq_capable    = 1,
 778         .name           = "sched_expedited"
 779 };
 780
 781 /*
 782  * RCU torture priority-boost testing.  Runs one real-time thread per
 783  * CPU for moderate bursts, repeatedly registering RCU callbacks and
 784  * spinning waiting for them to be invoked.  If a given callback takes
 785  * too long to be invoked, we assume that priority inversion has occurred.
 786  */
 787
 788 struct rcu_boost_inflight {
 789         struct rcu_head rcu;
 790         int inflight;
 791 };
 792
 793 static void rcu_torture_boost_cb(struct rcu_head *head)
 794 {
 795         struct rcu_boost_inflight *rbip =
 796                 container_of(head, struct rcu_boost_inflight, rcu);
 797
 798         smp_mb(); /* Ensure RCU-core accesses precede clearing ->inflight */
 799         rbip->inflight = 0;
 800 }
 801
 802 static int rcu_torture_boost(void *arg)
 803 {
 804         unsigned long call_rcu_time;
 805         unsigned long endtime;
 806         unsigned long oldstarttime;
 807         struct rcu_boost_inflight rbi = { .inflight = 0 };
 808         struct sched_param sp;
 809
 810         VERBOSE_PRINTK_STRING("rcu_torture_boost started");
 811
 812         /* Set real-time priority. */
 813         sp.sched_priority = 1;
 814         if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 815                 VERBOSE_PRINTK_STRING("rcu_torture_boost RT prio failed!");
 816                 n_rcu_torture_boost_rterror++;
 817         }
 818
 819         init_rcu_head_on_stack(&rbi.rcu);
 820         /* Each pass through the following loop does one boost-test cycle. */
 821         do {
 822                 /* Wait for the next test interval. */
 823                 oldstarttime = boost_starttime;
 824                 while (ULONG_CMP_LT(jiffies, oldstarttime)) {
 825                         schedule_timeout_interruptible(oldstarttime - jiffies);
 826                         rcu_stutter_wait("rcu_torture_boost");
 827                         if (kthread_should_stop() ||
 828                             fullstop != FULLSTOP_DONTSTOP)
 829                                 goto checkwait;
 830                 }
 831
 832                 /* Do one boost-test interval. */
 833                 endtime = oldstarttime + test_boost_duration * HZ;
 834                 call_rcu_time = jiffies;
 835                 while (ULONG_CMP_LT(jiffies, endtime)) {
 836                         /* If we don't have a callback in flight, post one. */
 837                         if (!rbi.inflight) {
 838                                 smp_mb(); /* RCU core before ->inflight = 1. */
 839                                 rbi.inflight = 1;
 840                                 call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 841                                 if (jiffies - call_rcu_time >
 842                                          test_boost_duration * HZ - HZ / 2) {
 843                                         VERBOSE_PRINTK_STRING("rcu_torture_boost boosting failed");
 844                                         n_rcu_torture_boost_failure++;
 845                                 }
 846                                 call_rcu_time = jiffies;
 847                         }
 848                         cond_resched();
 849                         rcu_stutter_wait("rcu_torture_boost");
 850                         if (kthread_should_stop() ||
 851                             fullstop != FULLSTOP_DONTSTOP)
 852                                 goto checkwait;
 853                 }
 854
 855                 /*
 856                  * Set the start time of the next test interval.
 857                  * Yes, this is vulnerable to long delays, but such
 858                  * delays simply cause a false negative for the next
 859                  * interval.  Besides, we are running at RT priority,
 860                  * so delays should be relatively rare.
 861                  */
 862                 while (oldstarttime == boost_starttime &&
 863                        !kthread_should_stop()) {
 864                         if (mutex_trylock(&boost_mutex)) {
 865                                 boost_starttime = jiffies +
 866                                                   test_boost_interval * HZ;
 867                                 n_rcu_torture_boosts++;
 868                                 mutex_unlock(&boost_mutex);
 869                                 break;
 870                         }
 871                         schedule_timeout_uninterruptible(1);
 872                 }
 873
 874                 /* Go do the stutter. */
 875 checkwait:      rcu_stutter_wait("rcu_torture_boost");
 876         } while (!kthread_should_stop() && fullstop  == FULLSTOP_DONTSTOP);
 877
 878         /* Clean up and exit. */
 879         VERBOSE_PRINTK_STRING("rcu_torture_boost task stopping");
 880         rcutorture_shutdown_absorb("rcu_torture_boost");
 881         while (!kthread_should_stop() || rbi.inflight)
 882                 schedule_timeout_uninterruptible(1);
 883         smp_mb(); /* order accesses to ->inflight before stack-frame death. */
 884         destroy_rcu_head_on_stack(&rbi.rcu);
 885         return 0;
 886 }
 887
 888 /*
 889  * RCU torture force-quiescent-state kthread.  Repeatedly induces
 890  * bursts of calls to force_quiescent_state(), increasing the probability
 891  * of occurrence of some important types of race conditions.
 892  */
 893 static int
 894 rcu_torture_fqs(void *arg)
 895 {
 896         unsigned long fqs_resume_time;
 897         int fqs_burst_remaining;
 898
 899         VERBOSE_PRINTK_STRING("rcu_torture_fqs task started");
 900         do {
 901                 fqs_resume_time = jiffies + fqs_stutter * HZ;
 902                 while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
 903                        !kthread_should_stop()) {
 904                         schedule_timeout_interruptible(1);
 905                 }
 906                 fqs_burst_remaining = fqs_duration;
 907                 while (fqs_burst_remaining > 0 &&
 908                        !kthread_should_stop()) {
 909                         cur_ops->fqs();
 910                         udelay(fqs_holdoff);
 911                         fqs_burst_remaining -= fqs_holdoff;
 912                 }
 913                 rcu_stutter_wait("rcu_torture_fqs");
 914         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 915         VERBOSE_PRINTK_STRING("rcu_torture_fqs task stopping");
 916         rcutorture_shutdown_absorb("rcu_torture_fqs");
 917         while (!kthread_should_stop())
 918                 schedule_timeout_uninterruptible(1);
 919         return 0;
 920 }
 921
 922 /*
 923  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 924  * for that pointed to by rcu_torture_current, freeing the old structure
 925  * after a series of grace periods (the "pipeline").
 926  */
 927 static int
 928 rcu_torture_writer(void *arg)
 929 {
 930         int i;
 931         long oldbatch = rcu_batches_completed();
 932         struct rcu_torture *rp;
 933         struct rcu_torture *old_rp;
 934         static DEFINE_RCU_RANDOM(rand);
 935
 936         VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
 937         set_user_nice(current, 19);
 938
 939         do {
 940                 schedule_timeout_uninterruptible(1);
 941                 rp = rcu_torture_alloc();
 942                 if (rp == NULL)
 943                         continue;
 944                 rp->rtort_pipe_count = 0;
 945                 udelay(rcu_random(&rand) & 0x3ff);
 946                 old_rp = rcu_dereference_check(rcu_torture_current,
 947                                                current == writer_task);
 948                 rp->rtort_mbtest = 1;
 949                 rcu_assign_pointer(rcu_torture_current, rp);
 950                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
 951                 if (old_rp) {
 952                         i = old_rp->rtort_pipe_count;
 953                         if (i > RCU_TORTURE_PIPE_LEN)
 954                                 i = RCU_TORTURE_PIPE_LEN;
 955                         atomic_inc(&rcu_torture_wcount[i]);
 956                         old_rp->rtort_pipe_count++;
 957                         cur_ops->deferred_free(old_rp);
 958                 }
 959                 rcutorture_record_progress(++rcu_torture_current_version);
 960                 oldbatch = cur_ops->completed();
 961                 rcu_stutter_wait("rcu_torture_writer");
 962         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 963         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
 964         rcutorture_shutdown_absorb("rcu_torture_writer");
 965         while (!kthread_should_stop())
 966                 schedule_timeout_uninterruptible(1);
 967         return 0;
 968 }
 969
 970 /*
 971  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
 972  * delay between calls.
 973  */
 974 static int
 975 rcu_torture_fakewriter(void *arg)
 976 {
 977         DEFINE_RCU_RANDOM(rand);
 978
 979         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
 980         set_user_nice(current, 19);
 981
 982         do {
 983                 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
 984                 udelay(rcu_random(&rand) & 0x3ff);
 985                 if (cur_ops->cb_barrier != NULL &&
 986                     rcu_random(&rand) % (nfakewriters * 8) == 0)
 987                         cur_ops->cb_barrier();
 988                 else
 989                         cur_ops->sync();
 990                 rcu_stutter_wait("rcu_torture_fakewriter");
 991         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 992
 993         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
 994         rcutorture_shutdown_absorb("rcu_torture_fakewriter");
 995         while (!kthread_should_stop())
 996                 schedule_timeout_uninterruptible(1);
 997         return 0;
 998 }
 999
1000 void rcutorture_trace_dump(void)
1001 {
1002         static atomic_t beenhere = ATOMIC_INIT(0);
1003
1004         if (atomic_read(&beenhere))
1005                 return;
1006         if (atomic_xchg(&beenhere, 1) != 0)
1007                 return;
1008         ftrace_dump(DUMP_ALL);
1009 }
1010
1011 /*
1012  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
1013  * incrementing the corresponding element of the pipeline array.  The
1014  * counter in the element should never be greater than 1, otherwise, the
1015  * RCU implementation is broken.
1016  */
1017 static void rcu_torture_timer(unsigned long unused)
1018 {
1019         int idx;
1020         int completed;
1021         int completed_end;
1022         static DEFINE_RCU_RANDOM(rand);
1023         static DEFINE_SPINLOCK(rand_lock);
1024         struct rcu_torture *p;
1025         int pipe_count;
1026         unsigned long long ts;
1027
1028         idx = cur_ops->readlock();
1029         completed = cur_ops->completed();
1030         ts = rcu_trace_clock_local();
1031         p = rcu_dereference_check(rcu_torture_current,
1032                                   rcu_read_lock_bh_held() ||
1033                                   rcu_read_lock_sched_held() ||
1034                                   srcu_read_lock_held(&srcu_ctl));
1035         if (p == NULL) {
1036                 /* Leave because rcu_torture_writer is not yet underway */
1037                 cur_ops->readunlock(idx);
1038                 return;
1039         }
1040         if (p->rtort_mbtest == 0)
1041                 atomic_inc(&n_rcu_torture_mberror);
1042         spin_lock(&rand_lock);
1043         cur_ops->read_delay(&rand);
1044         n_rcu_torture_timers++;
1045         spin_unlock(&rand_lock);
1046         preempt_disable();
1047         pipe_count = p->rtort_pipe_count;
1048         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1049                 /* Should not happen, but... */
1050                 pipe_count = RCU_TORTURE_PIPE_LEN;
1051         }
1052         completed_end = cur_ops->completed();
1053         if (pipe_count > 1) {
1054                 do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu, ts,
1055                                           completed, completed_end);
1056                 rcutorture_trace_dump();
1057         }
1058         __this_cpu_inc(rcu_torture_count[pipe_count]);
1059         completed = completed_end - completed;
1060         if (completed > RCU_TORTURE_PIPE_LEN) {
1061                 /* Should not happen, but... */
1062                 completed = RCU_TORTURE_PIPE_LEN;
1063         }
1064         __this_cpu_inc(rcu_torture_batch[completed]);
1065         preempt_enable();
1066         cur_ops->readunlock(idx);
1067 }
1068
1069 /*
1070  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
1071  * incrementing the corresponding element of the pipeline array.  The
1072  * counter in the element should never be greater than 1, otherwise, the
1073  * RCU implementation is broken.
1074  */
1075 static int
1076 rcu_torture_reader(void *arg)
1077 {
1078         int completed;
1079         int completed_end;
1080         int idx;
1081         DEFINE_RCU_RANDOM(rand);
1082         struct rcu_torture *p;
1083         int pipe_count;
1084         struct timer_list t;
1085         unsigned long long ts;
1086
1087         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
1088         set_user_nice(current, 19);
1089         if (irqreader && cur_ops->irq_capable)
1090                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
1091
1092         do {
1093                 if (irqreader && cur_ops->irq_capable) {
1094                         if (!timer_pending(&t))
1095                                 mod_timer(&t, jiffies + 1);
1096                 }
1097                 idx = cur_ops->readlock();
1098                 completed = cur_ops->completed();
1099                 ts = rcu_trace_clock_local();
1100                 p = rcu_dereference_check(rcu_torture_current,
1101                                           rcu_read_lock_bh_held() ||
1102                                           rcu_read_lock_sched_held() ||
1103                                           srcu_read_lock_held(&srcu_ctl));
1104                 if (p == NULL) {
1105                         /* Wait for rcu_torture_writer to get underway */
1106                         cur_ops->readunlock(idx);
1107                         schedule_timeout_interruptible(HZ);
1108                         continue;
1109                 }
1110                 if (p->rtort_mbtest == 0)
1111                         atomic_inc(&n_rcu_torture_mberror);
1112                 cur_ops->read_delay(&rand);
1113                 preempt_disable();
1114                 pipe_count = p->rtort_pipe_count;
1115                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1116                         /* Should not happen, but... */
1117                         pipe_count = RCU_TORTURE_PIPE_LEN;
1118                 }
1119                 completed_end = cur_ops->completed();
1120                 if (pipe_count > 1) {
1121                         do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
1122                                                   ts, completed, completed_end);
1123                         rcutorture_trace_dump();
1124                 }
1125                 __this_cpu_inc(rcu_torture_count[pipe_count]);
1126                 completed = completed_end - completed;
1127                 if (completed > RCU_TORTURE_PIPE_LEN) {
1128                         /* Should not happen, but... */
1129                         completed = RCU_TORTURE_PIPE_LEN;
1130                 }
1131                 __this_cpu_inc(rcu_torture_batch[completed]);
1132                 preempt_enable();
1133                 cur_ops->readunlock(idx);
1134                 schedule();
1135                 rcu_stutter_wait("rcu_torture_reader");
1136         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1137         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
1138         rcutorture_shutdown_absorb("rcu_torture_reader");
1139         if (irqreader && cur_ops->irq_capable)
1140                 del_timer_sync(&t);
1141         while (!kthread_should_stop())
1142                 schedule_timeout_uninterruptible(1);
1143         return 0;
1144 }
1145
1146 /*
1147  * Create an RCU-torture statistics message in the specified buffer.
1148  */
1149 static int
1150 rcu_torture_printk(char *page)
1151 {
1152         int cnt = 0;
1153         int cpu;
1154         int i;
1155         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1156         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1157
1158         for_each_possible_cpu(cpu) {
1159                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1160                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1161                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1162                 }
1163         }
1164         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1165                 if (pipesummary[i] != 0)
1166                         break;
1167         }
1168         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
1169         cnt += sprintf(&page[cnt],
1170                        "rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
1171                        rcu_torture_current,
1172                        rcu_torture_current_version,
1173                        list_empty(&rcu_torture_freelist),
1174                        atomic_read(&n_rcu_torture_alloc),
1175                        atomic_read(&n_rcu_torture_alloc_fail),
1176                        atomic_read(&n_rcu_torture_free));
1177         cnt += sprintf(&page[cnt], "rtmbe: %d rtbke: %ld rtbre: %ld ",
1178                        atomic_read(&n_rcu_torture_mberror),
1179                        n_rcu_torture_boost_ktrerror,
1180                        n_rcu_torture_boost_rterror);
1181         cnt += sprintf(&page[cnt], "rtbf: %ld rtb: %ld nt: %ld ",
1182                        n_rcu_torture_boost_failure,
1183                        n_rcu_torture_boosts,
1184                        n_rcu_torture_timers);
1185         cnt += sprintf(&page[cnt],
1186                        "onoff: %ld/%ld:%ld/%ld %d,%d:%d,%d %lu:%lu (HZ=%d) ",
1187                        n_online_successes, n_online_attempts,
1188                        n_offline_successes, n_offline_attempts,
1189                        min_online, max_online,
1190                        min_offline, max_offline,
1191                        sum_online, sum_offline, HZ);
1192         cnt += sprintf(&page[cnt], "barrier: %ld/%ld:%ld",
1193                        n_barrier_successes,
1194                        n_barrier_attempts,
1195                        n_rcu_torture_barrier_error);
1196         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1197         if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1198             n_rcu_torture_barrier_error != 0 ||
1199             n_rcu_torture_boost_ktrerror != 0 ||
1200             n_rcu_torture_boost_rterror != 0 ||
1201             n_rcu_torture_boost_failure != 0 ||
1202             i > 1) {
1203                 cnt += sprintf(&page[cnt], "!!! ");
1204                 atomic_inc(&n_rcu_torture_error);
1205                 WARN_ON_ONCE(1);
1206         }
1207         cnt += sprintf(&page[cnt], "Reader Pipe: ");
1208         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1209                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
1210         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1211         cnt += sprintf(&page[cnt], "Reader Batch: ");
1212         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1213                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
1214         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1215         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
1216         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1217                 cnt += sprintf(&page[cnt], " %d",
1218                                atomic_read(&rcu_torture_wcount[i]));
1219         }
1220         cnt += sprintf(&page[cnt], "\n");
1221         if (cur_ops->stats)
1222                 cnt += cur_ops->stats(&page[cnt]);
1223         return cnt;
1224 }
1225
1226 /*
1227  * Print torture statistics.  Caller must ensure that there is only
1228  * one call to this function at a given time!!!  This is normally
1229  * accomplished by relying on the module system to only have one copy
1230  * of the module loaded, and then by giving the rcu_torture_stats
1231  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1232  * thread is not running).
1233  */
1234 static void
1235 rcu_torture_stats_print(void)
1236 {
1237         int cnt;
1238
1239         cnt = rcu_torture_printk(printk_buf);
1240         pr_alert("%s", printk_buf);
1241 }
1242
1243 /*
1244  * Periodically prints torture statistics, if periodic statistics printing
1245  * was specified via the stat_interval module parameter.
1246  *
1247  * No need to worry about fullstop here, since this one doesn't reference
1248  * volatile state or register callbacks.
1249  */
1250 static int
1251 rcu_torture_stats(void *arg)
1252 {
1253         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
1254         do {
1255                 schedule_timeout_interruptible(stat_interval * HZ);
1256                 rcu_torture_stats_print();
1257                 rcutorture_shutdown_absorb("rcu_torture_stats");
1258         } while (!kthread_should_stop());
1259         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
1260         return 0;
1261 }
1262
1263 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
1264
1265 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
1266  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
1267  */
1268 static void rcu_torture_shuffle_tasks(void)
1269 {
1270         int i;
1271
1272         cpumask_setall(shuffle_tmp_mask);
1273         get_online_cpus();
1274
1275         /* No point in shuffling if there is only one online CPU (ex: UP) */
1276         if (num_online_cpus() == 1) {
1277                 put_online_cpus();
1278                 return;
1279         }
1280
1281         if (rcu_idle_cpu != -1)
1282                 cpumask_clear_cpu(rcu_idle_cpu, shuffle_tmp_mask);
1283
1284         set_cpus_allowed_ptr(current, shuffle_tmp_mask);
1285
1286         if (reader_tasks) {
1287                 for (i = 0; i < nrealreaders; i++)
1288                         if (reader_tasks[i])
1289                                 set_cpus_allowed_ptr(reader_tasks[i],
1290                                                      shuffle_tmp_mask);
1291         }
1292         if (fakewriter_tasks) {
1293                 for (i = 0; i < nfakewriters; i++)
1294                         if (fakewriter_tasks[i])
1295                                 set_cpus_allowed_ptr(fakewriter_tasks[i],
1296                                                      shuffle_tmp_mask);
1297         }
1298         if (writer_task)
1299                 set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
1300         if (stats_task)
1301                 set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
1302         if (stutter_task)
1303                 set_cpus_allowed_ptr(stutter_task, shuffle_tmp_mask);
1304         if (fqs_task)
1305                 set_cpus_allowed_ptr(fqs_task, shuffle_tmp_mask);
1306         if (shutdown_task)
1307                 set_cpus_allowed_ptr(shutdown_task, shuffle_tmp_mask);
1308 #ifdef CONFIG_HOTPLUG_CPU
1309         if (onoff_task)
1310                 set_cpus_allowed_ptr(onoff_task, shuffle_tmp_mask);
1311 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
1312         if (stall_task)
1313                 set_cpus_allowed_ptr(stall_task, shuffle_tmp_mask);
1314         if (barrier_cbs_tasks)
1315                 for (i = 0; i < n_barrier_cbs; i++)
1316                         if (barrier_cbs_tasks[i])
1317                                 set_cpus_allowed_ptr(barrier_cbs_tasks[i],
1318                                                      shuffle_tmp_mask);
1319         if (barrier_task)
1320                 set_cpus_allowed_ptr(barrier_task, shuffle_tmp_mask);
1321
1322         if (rcu_idle_cpu == -1)
1323                 rcu_idle_cpu = num_online_cpus() - 1;
1324         else
1325                 rcu_idle_cpu--;
1326
1327         put_online_cpus();
1328 }
1329
1330 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
1331  * system to become idle at a time and cut off its timer ticks. This is meant
1332  * to test the support for such tickless idle CPU in RCU.
1333  */
1334 static int
1335 rcu_torture_shuffle(void *arg)
1336 {
1337         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
1338         do {
1339                 schedule_timeout_interruptible(shuffle_interval * HZ);
1340                 rcu_torture_shuffle_tasks();
1341                 rcutorture_shutdown_absorb("rcu_torture_shuffle");
1342         } while (!kthread_should_stop());
1343         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
1344         return 0;
1345 }
1346
1347 /* Cause the rcutorture test to "stutter", starting and stopping all
1348  * threads periodically.
1349  */
1350 static int
1351 rcu_torture_stutter(void *arg)
1352 {
1353         VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
1354         do {
1355                 schedule_timeout_interruptible(stutter * HZ);
1356                 stutter_pause_test = 1;
1357                 if (!kthread_should_stop())
1358                         schedule_timeout_interruptible(stutter * HZ);
1359                 stutter_pause_test = 0;
1360                 rcutorture_shutdown_absorb("rcu_torture_stutter");
1361         } while (!kthread_should_stop());
1362         VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
1363         return 0;
1364 }
1365
1366 static inline void
1367 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, char *tag)
1368 {
1369         pr_alert("%s" TORTURE_FLAG
1370                  "--- %s: nreaders=%d nfakewriters=%d "
1371                  "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1372                  "shuffle_interval=%d stutter=%d irqreader=%d "
1373                  "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1374                  "test_boost=%d/%d test_boost_interval=%d "
1375                  "test_boost_duration=%d shutdown_secs=%d "
1376                  "stall_cpu=%d stall_cpu_holdoff=%d "
1377                  "n_barrier_cbs=%d "
1378                  "onoff_interval=%d onoff_holdoff=%d\n",
1379                  torture_type, tag, nrealreaders, nfakewriters,
1380                  stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1381                  stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1382                  test_boost, cur_ops->can_boost,
1383                  test_boost_interval, test_boost_duration, shutdown_secs,
1384                  stall_cpu, stall_cpu_holdoff,
1385                  n_barrier_cbs,
1386                  onoff_interval, onoff_holdoff);
1387 }
1388
1389 static struct notifier_block rcutorture_shutdown_nb = {
1390         .notifier_call = rcutorture_shutdown_notify,
1391 };
1392
1393 static void rcutorture_booster_cleanup(int cpu)
1394 {
1395         struct task_struct *t;
1396
1397         if (boost_tasks[cpu] == NULL)
1398                 return;
1399         mutex_lock(&boost_mutex);
1400         VERBOSE_PRINTK_STRING("Stopping rcu_torture_boost task");
1401         t = boost_tasks[cpu];
1402         boost_tasks[cpu] = NULL;
1403         mutex_unlock(&boost_mutex);
1404
1405         /* This must be outside of the mutex, otherwise deadlock! */
1406         kthread_stop(t);
1407         boost_tasks[cpu] = NULL;
1408 }
1409
1410 static int rcutorture_booster_init(int cpu)
1411 {
1412         int retval;
1413
1414         if (boost_tasks[cpu] != NULL)
1415                 return 0;  /* Already created, nothing more to do. */
1416
1417         /* Don't allow time recalculation while creating a new task. */
1418         mutex_lock(&boost_mutex);
1419         VERBOSE_PRINTK_STRING("Creating rcu_torture_boost task");
1420         boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1421                                                   cpu_to_node(cpu),
1422                                                   "rcu_torture_boost");
1423         if (IS_ERR(boost_tasks[cpu])) {
1424                 retval = PTR_ERR(boost_tasks[cpu]);
1425                 VERBOSE_PRINTK_STRING("rcu_torture_boost task create failed");
1426                 n_rcu_torture_boost_ktrerror++;
1427                 boost_tasks[cpu] = NULL;
1428                 mutex_unlock(&boost_mutex);
1429                 return retval;
1430         }
1431         kthread_bind(boost_tasks[cpu], cpu);
1432         wake_up_process(boost_tasks[cpu]);
1433         mutex_unlock(&boost_mutex);
1434         return 0;
1435 }
1436
1437 /*
1438  * Cause the rcutorture test to shutdown the system after the test has
1439  * run for the time specified by the shutdown_secs module parameter.
1440  */
1441 static int
1442 rcu_torture_shutdown(void *arg)
1443 {
1444         long delta;
1445         unsigned long jiffies_snap;
1446
1447         VERBOSE_PRINTK_STRING("rcu_torture_shutdown task started");
1448         jiffies_snap = ACCESS_ONCE(jiffies);
1449         while (ULONG_CMP_LT(jiffies_snap, shutdown_time) &&
1450                !kthread_should_stop()) {
1451                 delta = shutdown_time - jiffies_snap;
1452                 if (verbose)
1453                         pr_alert("%s" TORTURE_FLAG
1454                                  "rcu_torture_shutdown task: %lu jiffies remaining\n",
1455                                  torture_type, delta);
1456                 schedule_timeout_interruptible(delta);
1457                 jiffies_snap = ACCESS_ONCE(jiffies);
1458         }
1459         if (kthread_should_stop()) {
1460                 VERBOSE_PRINTK_STRING("rcu_torture_shutdown task stopping");
1461                 return 0;
1462         }
1463
1464         /* OK, shut down the system. */
1465
1466         VERBOSE_PRINTK_STRING("rcu_torture_shutdown task shutting down system");
1467         shutdown_task = NULL;   /* Avoid self-kill deadlock. */
1468         rcu_torture_cleanup();  /* Get the success/failure message. */
1469         kernel_power_off();     /* Shut down the system. */
1470         return 0;
1471 }
1472
1473 #ifdef CONFIG_HOTPLUG_CPU
1474
1475 /*
1476  * Execute random CPU-hotplug operations at the interval specified
1477  * by the onoff_interval.
1478  */
1479 static int
1480 rcu_torture_onoff(void *arg)
1481 {
1482         int cpu;
1483         unsigned long delta;
1484         int maxcpu = -1;
1485         DEFINE_RCU_RANDOM(rand);
1486         int ret;
1487         unsigned long starttime;
1488
1489         VERBOSE_PRINTK_STRING("rcu_torture_onoff task started");
1490         for_each_online_cpu(cpu)
1491                 maxcpu = cpu;
1492         WARN_ON(maxcpu < 0);
1493         if (onoff_holdoff > 0) {
1494                 VERBOSE_PRINTK_STRING("rcu_torture_onoff begin holdoff");
1495                 schedule_timeout_interruptible(onoff_holdoff * HZ);
1496                 VERBOSE_PRINTK_STRING("rcu_torture_onoff end holdoff");
1497         }
1498         while (!kthread_should_stop()) {
1499                 cpu = (rcu_random(&rand) >> 4) % (maxcpu + 1);
1500                 if (cpu_online(cpu) && cpu_is_hotpluggable(cpu)) {
1501                         if (verbose)
1502                                 pr_alert("%s" TORTURE_FLAG
1503                                          "rcu_torture_onoff task: offlining %d\n",
1504                                          torture_type, cpu);
1505                         starttime = jiffies;
1506                         n_offline_attempts++;
1507                         ret = cpu_down(cpu);
1508                         if (ret) {
1509                                 if (verbose)
1510                                         pr_alert("%s" TORTURE_FLAG
1511                                                  "rcu_torture_onoff task: offline %d failed: errno %d\n",
1512                                                  torture_type, cpu, ret);
1513                         } else {
1514                                 if (verbose)
1515                                         pr_alert("%s" TORTURE_FLAG
1516                                                  "rcu_torture_onoff task: offlined %d\n",
1517                                                  torture_type, cpu);
1518                                 n_offline_successes++;
1519                                 delta = jiffies - starttime;
1520                                 sum_offline += delta;
1521                                 if (min_offline < 0) {
1522                                         min_offline = delta;
1523                                         max_offline = delta;
1524                                 }
1525                                 if (min_offline > delta)
1526                                         min_offline = delta;
1527                                 if (max_offline < delta)
1528                                         max_offline = delta;
1529                         }
1530                 } else if (cpu_is_hotpluggable(cpu)) {
1531                         if (verbose)
1532                                 pr_alert("%s" TORTURE_FLAG
1533                                          "rcu_torture_onoff task: onlining %d\n",
1534                                          torture_type, cpu);
1535                         starttime = jiffies;
1536                         n_online_attempts++;
1537                         if (cpu_up(cpu) == 0) {
1538                                 if (verbose)
1539                                         pr_alert("%s" TORTURE_FLAG
1540                                                  "rcu_torture_onoff task: onlined %d\n",
1541                                                  torture_type, cpu);
1542                                 n_online_successes++;
1543                                 delta = jiffies - starttime;
1544                                 sum_online += delta;
1545                                 if (min_online < 0) {
1546                                         min_online = delta;
1547                                         max_online = delta;
1548                                 }
1549                                 if (min_online > delta)
1550                                         min_online = delta;
1551                                 if (max_online < delta)
1552                                         max_online = delta;
1553                         }
1554                 }
1555                 schedule_timeout_interruptible(onoff_interval * HZ);
1556         }
1557         VERBOSE_PRINTK_STRING("rcu_torture_onoff task stopping");
1558         return 0;
1559 }
1560
1561 static int
1562 rcu_torture_onoff_init(void)
1563 {
1564         int ret;
1565
1566         if (onoff_interval <= 0)
1567                 return 0;
1568         onoff_task = kthread_run(rcu_torture_onoff, NULL, "rcu_torture_onoff");
1569         if (IS_ERR(onoff_task)) {
1570                 ret = PTR_ERR(onoff_task);
1571                 onoff_task = NULL;
1572                 return ret;
1573         }
1574         return 0;
1575 }
1576
1577 static void rcu_torture_onoff_cleanup(void)
1578 {
1579         if (onoff_task == NULL)
1580                 return;
1581         VERBOSE_PRINTK_STRING("Stopping rcu_torture_onoff task");
1582         kthread_stop(onoff_task);
1583         onoff_task = NULL;
1584 }
1585
1586 #else /* #ifdef CONFIG_HOTPLUG_CPU */
1587
1588 static int
1589 rcu_torture_onoff_init(void)
1590 {
1591         return 0;
1592 }
1593
1594 static void rcu_torture_onoff_cleanup(void)
1595 {
1596 }
1597
1598 #endif /* #else #ifdef CONFIG_HOTPLUG_CPU */
1599
1600 /*
1601  * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
1602  * induces a CPU stall for the time specified by stall_cpu.
1603  */
1604 static int rcu_torture_stall(void *args)
1605 {
1606         unsigned long stop_at;
1607
1608         VERBOSE_PRINTK_STRING("rcu_torture_stall task started");
1609         if (stall_cpu_holdoff > 0) {
1610                 VERBOSE_PRINTK_STRING("rcu_torture_stall begin holdoff");
1611                 schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1612                 VERBOSE_PRINTK_STRING("rcu_torture_stall end holdoff");
1613         }
1614         if (!kthread_should_stop()) {
1615                 stop_at = get_seconds() + stall_cpu;
1616                 /* RCU CPU stall is expected behavior in following code. */
1617                 pr_alert("rcu_torture_stall start.\n");
1618                 rcu_read_lock();
1619                 preempt_disable();
1620                 while (ULONG_CMP_LT(get_seconds(), stop_at))
1621                         continue;  /* Induce RCU CPU stall warning. */
1622                 preempt_enable();
1623                 rcu_read_unlock();
1624                 pr_alert("rcu_torture_stall end.\n");
1625         }
1626         rcutorture_shutdown_absorb("rcu_torture_stall");
1627         while (!kthread_should_stop())
1628                 schedule_timeout_interruptible(10 * HZ);
1629         return 0;
1630 }
1631
1632 /* Spawn CPU-stall kthread, if stall_cpu specified. */
1633 static int __init rcu_torture_stall_init(void)
1634 {
1635         int ret;
1636
1637         if (stall_cpu <= 0)
1638                 return 0;
1639         stall_task = kthread_run(rcu_torture_stall, NULL, "rcu_torture_stall");
1640         if (IS_ERR(stall_task)) {
1641                 ret = PTR_ERR(stall_task);
1642                 stall_task = NULL;
1643                 return ret;
1644         }
1645         return 0;
1646 }
1647
1648 /* Clean up after the CPU-stall kthread, if one was spawned. */
1649 static void rcu_torture_stall_cleanup(void)
1650 {
1651         if (stall_task == NULL)
1652                 return;
1653         VERBOSE_PRINTK_STRING("Stopping rcu_torture_stall_task.");
1654         kthread_stop(stall_task);
1655         stall_task = NULL;
1656 }
1657
1658 /* Callback function for RCU barrier testing. */
1659 void rcu_torture_barrier_cbf(struct rcu_head *rcu)
1660 {
1661         atomic_inc(&barrier_cbs_invoked);
1662 }
1663
1664 /* kthread function to register callbacks used to test RCU barriers. */
1665 static int rcu_torture_barrier_cbs(void *arg)
1666 {
1667         long myid = (long)arg;
1668         bool lastphase = 0;
1669         struct rcu_head rcu;
1670
1671         init_rcu_head_on_stack(&rcu);
1672         VERBOSE_PRINTK_STRING("rcu_torture_barrier_cbs task started");
1673         set_user_nice(current, 19);
1674         do {
1675                 wait_event(barrier_cbs_wq[myid],
1676                            barrier_phase != lastphase ||
1677                            kthread_should_stop() ||
1678                            fullstop != FULLSTOP_DONTSTOP);
1679                 lastphase = barrier_phase;
1680                 smp_mb(); /* ensure barrier_phase load before ->call(). */
1681                 if (kthread_should_stop() || fullstop != FULLSTOP_DONTSTOP)
1682                         break;
1683                 cur_ops->call(&rcu, rcu_torture_barrier_cbf);
1684                 if (atomic_dec_and_test(&barrier_cbs_count))
1685                         wake_up(&barrier_wq);
1686         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1687         VERBOSE_PRINTK_STRING("rcu_torture_barrier_cbs task stopping");
1688         rcutorture_shutdown_absorb("rcu_torture_barrier_cbs");
1689         while (!kthread_should_stop())
1690                 schedule_timeout_interruptible(1);
1691         cur_ops->cb_barrier();
1692         destroy_rcu_head_on_stack(&rcu);
1693         return 0;
1694 }
1695
1696 /* kthread function to drive and coordinate RCU barrier testing. */
1697 static int rcu_torture_barrier(void *arg)
1698 {
1699         int i;
1700
1701         VERBOSE_PRINTK_STRING("rcu_torture_barrier task starting");
1702         do {
1703                 atomic_set(&barrier_cbs_invoked, 0);
1704                 atomic_set(&barrier_cbs_count, n_barrier_cbs);
1705                 smp_mb(); /* Ensure barrier_phase after prior assignments. */
1706                 barrier_phase = !barrier_phase;
1707                 for (i = 0; i < n_barrier_cbs; i++)
1708                         wake_up(&barrier_cbs_wq[i]);
1709                 wait_event(barrier_wq,
1710                            atomic_read(&barrier_cbs_count) == 0 ||
1711                            kthread_should_stop() ||
1712                            fullstop != FULLSTOP_DONTSTOP);
1713                 if (kthread_should_stop() || fullstop != FULLSTOP_DONTSTOP)
1714                         break;
1715                 n_barrier_attempts++;
1716                 cur_ops->cb_barrier();
1717                 if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
1718                         n_rcu_torture_barrier_error++;
1719                         WARN_ON_ONCE(1);
1720                 }
1721                 n_barrier_successes++;
1722                 schedule_timeout_interruptible(HZ / 10);
1723         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1724         VERBOSE_PRINTK_STRING("rcu_torture_barrier task stopping");
1725         rcutorture_shutdown_absorb("rcu_torture_barrier");
1726         while (!kthread_should_stop())
1727                 schedule_timeout_interruptible(1);
1728         return 0;
1729 }
1730
1731 /* Initialize RCU barrier testing. */
1732 static int rcu_torture_barrier_init(void)
1733 {
1734         int i;
1735         int ret;
1736
1737         if (n_barrier_cbs == 0)
1738                 return 0;
1739         if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
1740                 pr_alert("%s" TORTURE_FLAG
1741                          " Call or barrier ops missing for %s,\n",
1742                          torture_type, cur_ops->name);
1743                 pr_alert("%s" TORTURE_FLAG
1744                          " RCU barrier testing omitted from run.\n",
1745                          torture_type);
1746                 return 0;
1747         }
1748         atomic_set(&barrier_cbs_count, 0);
1749         atomic_set(&barrier_cbs_invoked, 0);
1750         barrier_cbs_tasks =
1751                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_tasks[0]),
1752                         GFP_KERNEL);
1753         barrier_cbs_wq =
1754                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_wq[0]),
1755                         GFP_KERNEL);
1756         if (barrier_cbs_tasks == NULL || !barrier_cbs_wq)
1757                 return -ENOMEM;
1758         for (i = 0; i < n_barrier_cbs; i++) {
1759                 init_waitqueue_head(&barrier_cbs_wq[i]);
1760                 barrier_cbs_tasks[i] = kthread_run(rcu_torture_barrier_cbs,
1761                                                    (void *)(long)i,
1762                                                    "rcu_torture_barrier_cbs");
1763                 if (IS_ERR(barrier_cbs_tasks[i])) {
1764                         ret = PTR_ERR(barrier_cbs_tasks[i]);
1765                         VERBOSE_PRINTK_ERRSTRING("Failed to create rcu_torture_barrier_cbs");
1766                         barrier_cbs_tasks[i] = NULL;
1767                         return ret;
1768                 }
1769         }
1770         barrier_task = kthread_run(rcu_torture_barrier, NULL,
1771                                    "rcu_torture_barrier");
1772         if (IS_ERR(barrier_task)) {
1773                 ret = PTR_ERR(barrier_task);
1774                 VERBOSE_PRINTK_ERRSTRING("Failed to create rcu_torture_barrier");
1775                 barrier_task = NULL;
1776         }
1777         return 0;
1778 }
1779
1780 /* Clean up after RCU barrier testing. */
1781 static void rcu_torture_barrier_cleanup(void)
1782 {
1783         int i;
1784
1785         if (barrier_task != NULL) {
1786                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_barrier task");
1787                 kthread_stop(barrier_task);
1788                 barrier_task = NULL;
1789         }
1790         if (barrier_cbs_tasks != NULL) {
1791                 for (i = 0; i < n_barrier_cbs; i++) {
1792                         if (barrier_cbs_tasks[i] != NULL) {
1793                                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_barrier_cbs task");
1794                                 kthread_stop(barrier_cbs_tasks[i]);
1795                                 barrier_cbs_tasks[i] = NULL;
1796                         }
1797                 }
1798                 kfree(barrier_cbs_tasks);
1799                 barrier_cbs_tasks = NULL;
1800         }
1801         if (barrier_cbs_wq != NULL) {
1802                 kfree(barrier_cbs_wq);
1803                 barrier_cbs_wq = NULL;
1804         }
1805 }
1806
1807 static int rcutorture_cpu_notify(struct notifier_block *self,
1808                                  unsigned long action, void *hcpu)
1809 {
1810         long cpu = (long)hcpu;
1811
1812         switch (action) {
1813         case CPU_ONLINE:
1814         case CPU_DOWN_FAILED:
1815                 (void)rcutorture_booster_init(cpu);
1816                 break;
1817         case CPU_DOWN_PREPARE:
1818                 rcutorture_booster_cleanup(cpu);
1819                 break;
1820         default:
1821                 break;
1822         }
1823         return NOTIFY_OK;
1824 }
1825
1826 static struct notifier_block rcutorture_cpu_nb = {
1827         .notifier_call = rcutorture_cpu_notify,
1828 };
1829
1830 static void
1831 rcu_torture_cleanup(void)
1832 {
1833         int i;
1834
1835         mutex_lock(&fullstop_mutex);
1836         rcutorture_record_test_transition();
1837         if (fullstop == FULLSTOP_SHUTDOWN) {
1838                 pr_warn(/* but going down anyway, so... */
1839                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
1840                 mutex_unlock(&fullstop_mutex);
1841                 schedule_timeout_uninterruptible(10);
1842                 if (cur_ops->cb_barrier != NULL)
1843                         cur_ops->cb_barrier();
1844                 return;
1845         }
1846         fullstop = FULLSTOP_RMMOD;
1847         mutex_unlock(&fullstop_mutex);
1848         unregister_reboot_notifier(&rcutorture_shutdown_nb);
1849         rcu_torture_barrier_cleanup();
1850         rcu_torture_stall_cleanup();
1851         if (stutter_task) {
1852                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
1853                 kthread_stop(stutter_task);
1854         }
1855         stutter_task = NULL;
1856         if (shuffler_task) {
1857                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
1858                 kthread_stop(shuffler_task);
1859                 free_cpumask_var(shuffle_tmp_mask);
1860         }
1861         shuffler_task = NULL;
1862
1863         if (writer_task) {
1864                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
1865                 kthread_stop(writer_task);
1866         }
1867         writer_task = NULL;
1868
1869         if (reader_tasks) {
1870                 for (i = 0; i < nrealreaders; i++) {
1871                         if (reader_tasks[i]) {
1872                                 VERBOSE_PRINTK_STRING(
1873                                         "Stopping rcu_torture_reader task");
1874                                 kthread_stop(reader_tasks[i]);
1875                         }
1876                         reader_tasks[i] = NULL;
1877                 }
1878                 kfree(reader_tasks);
1879                 reader_tasks = NULL;
1880         }
1881         rcu_torture_current = NULL;
1882
1883         if (fakewriter_tasks) {
1884                 for (i = 0; i < nfakewriters; i++) {
1885                         if (fakewriter_tasks[i]) {
1886                                 VERBOSE_PRINTK_STRING(
1887                                         "Stopping rcu_torture_fakewriter task");
1888                                 kthread_stop(fakewriter_tasks[i]);
1889                         }
1890                         fakewriter_tasks[i] = NULL;
1891                 }
1892                 kfree(fakewriter_tasks);
1893                 fakewriter_tasks = NULL;
1894         }
1895
1896         if (stats_task) {
1897                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
1898                 kthread_stop(stats_task);
1899         }
1900         stats_task = NULL;
1901
1902         if (fqs_task) {
1903                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_fqs task");
1904                 kthread_stop(fqs_task);
1905         }
1906         fqs_task = NULL;
1907         if ((test_boost == 1 && cur_ops->can_boost) ||
1908             test_boost == 2) {
1909                 unregister_cpu_notifier(&rcutorture_cpu_nb);
1910                 for_each_possible_cpu(i)
1911                         rcutorture_booster_cleanup(i);
1912         }
1913         if (shutdown_task != NULL) {
1914                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shutdown task");
1915                 kthread_stop(shutdown_task);
1916         }
1917         shutdown_task = NULL;
1918         rcu_torture_onoff_cleanup();
1919
1920         /* Wait for all RCU callbacks to fire.  */
1921
1922         if (cur_ops->cb_barrier != NULL)
1923                 cur_ops->cb_barrier();
1924
1925         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1926
1927         if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
1928                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1929         else if (n_online_successes != n_online_attempts ||
1930                  n_offline_successes != n_offline_attempts)
1931                 rcu_torture_print_module_parms(cur_ops,
1932                                                "End of test: RCU_HOTPLUG");
1933         else
1934                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1935 }
1936
1937 static int __init
1938 rcu_torture_init(void)
1939 {
1940         int i;
1941         int cpu;
1942         int firsterr = 0;
1943         int retval;
1944         static struct rcu_torture_ops *torture_ops[] =
1945                 { &rcu_ops, &rcu_sync_ops, &rcu_expedited_ops,
1946                   &rcu_bh_ops, &rcu_bh_sync_ops, &rcu_bh_expedited_ops,
1947                   &srcu_ops, &srcu_sync_ops, &srcu_expedited_ops,
1948                   &sched_ops, &sched_sync_ops, &sched_expedited_ops, };
1949
1950         mutex_lock(&fullstop_mutex);
1951
1952         /* Process args and tell the world that the torturer is on the job. */
1953         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1954                 cur_ops = torture_ops[i];
1955                 if (strcmp(torture_type, cur_ops->name) == 0)
1956                         break;
1957         }
1958         if (i == ARRAY_SIZE(torture_ops)) {
1959                 pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
1960                          torture_type);
1961                 pr_alert("rcu-torture types:");
1962                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1963                         pr_alert(" %s", torture_ops[i]->name);
1964                 pr_alert("\n");
1965                 mutex_unlock(&fullstop_mutex);
1966                 return -EINVAL;
1967         }
1968         if (cur_ops->fqs == NULL && fqs_duration != 0) {
1969                 pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
1970                 fqs_duration = 0;
1971         }
1972         if (cur_ops->init)
1973                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1974
1975         if (nreaders >= 0)
1976                 nrealreaders = nreaders;
1977         else
1978                 nrealreaders = 2 * num_online_cpus();
1979         rcu_torture_print_module_parms(cur_ops, "Start of test");
1980         fullstop = FULLSTOP_DONTSTOP;
1981
1982         /* Set up the freelist. */
1983
1984         INIT_LIST_HEAD(&rcu_torture_freelist);
1985         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1986                 rcu_tortures[i].rtort_mbtest = 0;
1987                 list_add_tail(&rcu_tortures[i].rtort_free,
1988                               &rcu_torture_freelist);
1989         }
1990
1991         /* Initialize the statistics so that each run gets its own numbers. */
1992
1993         rcu_torture_current = NULL;
1994         rcu_torture_current_version = 0;
1995         atomic_set(&n_rcu_torture_alloc, 0);
1996         atomic_set(&n_rcu_torture_alloc_fail, 0);
1997         atomic_set(&n_rcu_torture_free, 0);
1998         atomic_set(&n_rcu_torture_mberror, 0);
1999         atomic_set(&n_rcu_torture_error, 0);
2000         n_rcu_torture_barrier_error = 0;
2001         n_rcu_torture_boost_ktrerror = 0;
2002         n_rcu_torture_boost_rterror = 0;
2003         n_rcu_torture_boost_failure = 0;
2004         n_rcu_torture_boosts = 0;
2005         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
2006                 atomic_set(&rcu_torture_wcount[i], 0);
2007         for_each_possible_cpu(cpu) {
2008                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
2009                         per_cpu(rcu_torture_count, cpu)[i] = 0;
2010                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
2011                 }
2012         }
2013
2014         /* Start up the kthreads. */
2015
2016         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
2017         writer_task = kthread_create(rcu_torture_writer, NULL,
2018                                      "rcu_torture_writer");
2019         if (IS_ERR(writer_task)) {
2020                 firsterr = PTR_ERR(writer_task);
2021                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
2022                 writer_task = NULL;
2023                 goto unwind;
2024         }
2025         wake_up_process(writer_task);
2026         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
2027                                    GFP_KERNEL);
2028         if (fakewriter_tasks == NULL) {
2029                 VERBOSE_PRINTK_ERRSTRING("out of memory");
2030                 firsterr = -ENOMEM;
2031                 goto unwind;
2032         }
2033         for (i = 0; i < nfakewriters; i++) {
2034                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
2035                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
2036                                                   "rcu_torture_fakewriter");
2037                 if (IS_ERR(fakewriter_tasks[i])) {
2038                         firsterr = PTR_ERR(fakewriter_tasks[i]);
2039                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
2040                         fakewriter_tasks[i] = NULL;
2041                         goto unwind;
2042                 }
2043         }
2044         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
2045                                GFP_KERNEL);
2046         if (reader_tasks == NULL) {
2047                 VERBOSE_PRINTK_ERRSTRING("out of memory");
2048                 firsterr = -ENOMEM;
2049                 goto unwind;
2050         }
2051         for (i = 0; i < nrealreaders; i++) {
2052                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
2053                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
2054                                               "rcu_torture_reader");
2055                 if (IS_ERR(reader_tasks[i])) {
2056                         firsterr = PTR_ERR(reader_tasks[i]);
2057                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
2058                         reader_tasks[i] = NULL;
2059                         goto unwind;
2060                 }
2061         }
2062         if (stat_interval > 0) {
2063                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
2064                 stats_task = kthread_run(rcu_torture_stats, NULL,
2065                                         "rcu_torture_stats");
2066                 if (IS_ERR(stats_task)) {
2067                         firsterr = PTR_ERR(stats_task);
2068                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
2069                         stats_task = NULL;
2070                         goto unwind;
2071                 }
2072         }
2073         if (test_no_idle_hz) {
2074                 rcu_idle_cpu = num_online_cpus() - 1;
2075
2076                 if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
2077                         firsterr = -ENOMEM;
2078                         VERBOSE_PRINTK_ERRSTRING("Failed to alloc mask");
2079                         goto unwind;
2080                 }
2081
2082                 /* Create the shuffler thread */
2083                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
2084                                           "rcu_torture_shuffle");
2085                 if (IS_ERR(shuffler_task)) {
2086                         free_cpumask_var(shuffle_tmp_mask);
2087                         firsterr = PTR_ERR(shuffler_task);
2088                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
2089                         shuffler_task = NULL;
2090                         goto unwind;
2091                 }
2092         }
2093         if (stutter < 0)
2094                 stutter = 0;
2095         if (stutter) {
2096                 /* Create the stutter thread */
2097                 stutter_task = kthread_run(rcu_torture_stutter, NULL,
2098                                           "rcu_torture_stutter");
2099                 if (IS_ERR(stutter_task)) {
2100                         firsterr = PTR_ERR(stutter_task);
2101                         VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
2102                         stutter_task = NULL;
2103                         goto unwind;
2104                 }
2105         }
2106         if (fqs_duration < 0)
2107                 fqs_duration = 0;
2108         if (fqs_duration) {
2109                 /* Create the stutter thread */
2110                 fqs_task = kthread_run(rcu_torture_fqs, NULL,
2111                                        "rcu_torture_fqs");
2112                 if (IS_ERR(fqs_task)) {
2113                         firsterr = PTR_ERR(fqs_task);
2114                         VERBOSE_PRINTK_ERRSTRING("Failed to create fqs");
2115                         fqs_task = NULL;
2116                         goto unwind;
2117                 }
2118         }
2119         if (test_boost_interval < 1)
2120                 test_boost_interval = 1;
2121         if (test_boost_duration < 2)
2122                 test_boost_duration = 2;
2123         if ((test_boost == 1 && cur_ops->can_boost) ||
2124             test_boost == 2) {
2125
2126                 boost_starttime = jiffies + test_boost_interval * HZ;
2127                 register_cpu_notifier(&rcutorture_cpu_nb);
2128                 for_each_possible_cpu(i) {
2129                         if (cpu_is_offline(i))
2130                                 continue;  /* Heuristic: CPU can go offline. */
2131                         retval = rcutorture_booster_init(i);
2132                         if (retval < 0) {
2133                                 firsterr = retval;
2134                                 goto unwind;
2135                         }
2136                 }
2137         }
2138         if (shutdown_secs > 0) {
2139                 shutdown_time = jiffies + shutdown_secs * HZ;
2140                 shutdown_task = kthread_create(rcu_torture_shutdown, NULL,
2141                                                "rcu_torture_shutdown");
2142                 if (IS_ERR(shutdown_task)) {
2143                         firsterr = PTR_ERR(shutdown_task);
2144                         VERBOSE_PRINTK_ERRSTRING("Failed to create shutdown");
2145                         shutdown_task = NULL;
2146                         goto unwind;
2147                 }
2148                 wake_up_process(shutdown_task);
2149         }
2150         i = rcu_torture_onoff_init();
2151         if (i != 0) {
2152                 firsterr = i;
2153                 goto unwind;
2154         }
2155         register_reboot_notifier(&rcutorture_shutdown_nb);
2156         i = rcu_torture_stall_init();
2157         if (i != 0) {
2158                 firsterr = i;
2159                 goto unwind;
2160         }
2161         retval = rcu_torture_barrier_init();
2162         if (retval != 0) {
2163                 firsterr = retval;
2164                 goto unwind;
2165         }
2166         rcutorture_record_test_transition();
2167         mutex_unlock(&fullstop_mutex);
2168         return 0;
2169
2170 unwind:
2171         mutex_unlock(&fullstop_mutex);
2172         rcu_torture_cleanup();
2173         return firsterr;
2174 }
2175
2176 module_init(rcu_torture_init);
2177 module_exit(rcu_torture_cleanup);