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 fqs_duration;
  56 module_param(fqs_duration, int, 0444);
  57 MODULE_PARM_DESC(fqs_duration, "Duration of fqs bursts (us), 0 to disable");
  58 static int fqs_holdoff;
  59 module_param(fqs_holdoff, int, 0444);
  60 MODULE_PARM_DESC(fqs_holdoff, "Holdoff time within fqs bursts (us)");
  61 static int fqs_stutter = 3;
  62 module_param(fqs_stutter, int, 0444);
  63 MODULE_PARM_DESC(fqs_stutter, "Wait time between fqs bursts (s)");
  64 static bool gp_exp;
  65 module_param(gp_exp, bool, 0444);
  66 MODULE_PARM_DESC(gp_exp, "Use expedited GP wait primitives");
  67 static bool gp_normal;
  68 module_param(gp_normal, bool, 0444);
  69 MODULE_PARM_DESC(gp_normal, "Use normal (non-expedited) GP wait primitives");
  70 static int irqreader = 1;
  71 module_param(irqreader, int, 0444);
  72 MODULE_PARM_DESC(irqreader, "Allow RCU readers from irq handlers");
  73 static int n_barrier_cbs;
  74 module_param(n_barrier_cbs, int, 0444);
  75 MODULE_PARM_DESC(n_barrier_cbs, "# of callbacks/kthreads for barrier testing");
  76 static int nfakewriters = 4;
  77 module_param(nfakewriters, int, 0444);
  78 MODULE_PARM_DESC(nfakewriters, "Number of RCU fake writer threads");
  79 static int nreaders = -1;
  80 module_param(nreaders, int, 0444);
  81 MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
  82 static int object_debug;
  83 module_param(object_debug, int, 0444);
  84 MODULE_PARM_DESC(object_debug, "Enable debug-object double call_rcu() testing");
  85 static int onoff_holdoff;
  86 module_param(onoff_holdoff, int, 0444);
  87 MODULE_PARM_DESC(onoff_holdoff, "Time after boot before CPU hotplugs (s)");
  88 static int onoff_interval;
  89 module_param(onoff_interval, int, 0444);
  90 MODULE_PARM_DESC(onoff_interval, "Time between CPU hotplugs (s), 0=disable");
  91 static int shuffle_interval = 3;
  92 module_param(shuffle_interval, int, 0444);
  93 MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
  94 static int shutdown_secs;
  95 module_param(shutdown_secs, int, 0444);
  96 MODULE_PARM_DESC(shutdown_secs, "Shutdown time (s), <= zero to disable.");
  97 static int stall_cpu;
  98 module_param(stall_cpu, int, 0444);
  99 MODULE_PARM_DESC(stall_cpu, "Stall duration (s), zero to disable.");
 100 static int stall_cpu_holdoff = 10;
 101 module_param(stall_cpu_holdoff, int, 0444);
 102 MODULE_PARM_DESC(stall_cpu_holdoff, "Time to wait before starting stall (s).");
 103 static int stat_interval = 60;
 104 module_param(stat_interval, int, 0644);
 105 MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
 106 static int stutter = 5;
 107 module_param(stutter, int, 0444);
 108 MODULE_PARM_DESC(stutter, "Number of seconds to run/halt test");
 109 static int test_boost = 1;
 110 module_param(test_boost, int, 0444);
 111 MODULE_PARM_DESC(test_boost, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
 112 static int test_boost_duration = 4;
 113 module_param(test_boost_duration, int, 0444);
 114 MODULE_PARM_DESC(test_boost_duration, "Duration of each boost test, seconds.");
 115 static int test_boost_interval = 7;
 116 module_param(test_boost_interval, int, 0444);
 117 MODULE_PARM_DESC(test_boost_interval, "Interval between boost tests, seconds.");
 118 static bool test_no_idle_hz = true;
 119 module_param(test_no_idle_hz, bool, 0444);
 120 MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
 121 static char *torture_type = "rcu";
 122 module_param(torture_type, charp, 0444);
 123 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, ...)");
 124 static bool verbose;
 125 module_param(verbose, bool, 0444);
 126 MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
 127
 128 #define TORTURE_FLAG "-torture:"
 129 #define PRINTK_STRING(s) \
 130         do { pr_alert("%s" TORTURE_FLAG s "\n", torture_type); } while (0)
 131 #define VERBOSE_PRINTK_STRING(s) \
 132         do { if (verbose) pr_alert("%s" TORTURE_FLAG s "\n", torture_type); } while (0)
 133 #define VERBOSE_PRINTK_ERRSTRING(s) \
 134         do { if (verbose) pr_alert("%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
 135
 136 static char printk_buf[4096];
 137
 138 static int nrealreaders;
 139 static struct task_struct *writer_task;
 140 static struct task_struct **fakewriter_tasks;
 141 static struct task_struct **reader_tasks;
 142 static struct task_struct *stats_task;
 143 static struct task_struct *shuffler_task;
 144 static struct task_struct *stutter_task;
 145 static struct task_struct *fqs_task;
 146 static struct task_struct *boost_tasks[NR_CPUS];
 147 static struct task_struct *shutdown_task;
 148 #ifdef CONFIG_HOTPLUG_CPU
 149 static struct task_struct *onoff_task;
 150 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
 151 static struct task_struct *stall_task;
 152 static struct task_struct **barrier_cbs_tasks;
 153 static struct task_struct *barrier_task;
 154
 155 #define RCU_TORTURE_PIPE_LEN 10
 156
 157 struct rcu_torture {
 158         struct rcu_head rtort_rcu;
 159         int rtort_pipe_count;
 160         struct list_head rtort_free;
 161         int rtort_mbtest;
 162 };
 163
 164 static LIST_HEAD(rcu_torture_freelist);
 165 static struct rcu_torture __rcu *rcu_torture_current;
 166 static unsigned long rcu_torture_current_version;
 167 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 168 static DEFINE_SPINLOCK(rcu_torture_lock);
 169 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
 170         { 0 };
 171 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) =
 172         { 0 };
 173 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 174 static atomic_t n_rcu_torture_alloc;
 175 static atomic_t n_rcu_torture_alloc_fail;
 176 static atomic_t n_rcu_torture_free;
 177 static atomic_t n_rcu_torture_mberror;
 178 static atomic_t n_rcu_torture_error;
 179 static long n_rcu_torture_barrier_error;
 180 static long n_rcu_torture_boost_ktrerror;
 181 static long n_rcu_torture_boost_rterror;
 182 static long n_rcu_torture_boost_failure;
 183 static long n_rcu_torture_boosts;
 184 static long n_rcu_torture_timers;
 185 static long n_offline_attempts;
 186 static long n_offline_successes;
 187 static unsigned long sum_offline;
 188 static int min_offline = -1;
 189 static int max_offline;
 190 static long n_online_attempts;
 191 static long n_online_successes;
 192 static unsigned long sum_online;
 193 static int min_online = -1;
 194 static int max_online;
 195 static long n_barrier_attempts;
 196 static long n_barrier_successes;
 197 static struct list_head rcu_torture_removed;
 198 static cpumask_var_t shuffle_tmp_mask;
 199
 200 static int stutter_pause_test;
 201
 202 #if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
 203 #define RCUTORTURE_RUNNABLE_INIT 1
 204 #else
 205 #define RCUTORTURE_RUNNABLE_INIT 0
 206 #endif
 207 int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT;
 208 module_param(rcutorture_runnable, int, 0444);
 209 MODULE_PARM_DESC(rcutorture_runnable, "Start rcutorture at boot");
 210
 211 #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
 212 #define rcu_can_boost() 1
 213 #else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 214 #define rcu_can_boost() 0
 215 #endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 216
 217 #ifdef CONFIG_RCU_TRACE
 218 static u64 notrace rcu_trace_clock_local(void)
 219 {
 220         u64 ts = trace_clock_local();
 221         unsigned long __maybe_unused ts_rem = do_div(ts, NSEC_PER_USEC);
 222         return ts;
 223 }
 224 #else /* #ifdef CONFIG_RCU_TRACE */
 225 static u64 notrace rcu_trace_clock_local(void)
 226 {
 227         return 0ULL;
 228 }
 229 #endif /* #else #ifdef CONFIG_RCU_TRACE */
 230
 231 static unsigned long shutdown_time;     /* jiffies to system shutdown. */
 232 static unsigned long boost_starttime;   /* jiffies of next boost test start. */
 233 DEFINE_MUTEX(boost_mutex);              /* protect setting boost_starttime */
 234                                         /*  and boost task create/destroy. */
 235 static atomic_t barrier_cbs_count;      /* Barrier callbacks registered. */
 236 static bool barrier_phase;              /* Test phase. */
 237 static atomic_t barrier_cbs_invoked;    /* Barrier callbacks invoked. */
 238 static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */
 239 static DECLARE_WAIT_QUEUE_HEAD(barrier_wq);
 240
 241 /* Mediate rmmod and system shutdown.  Concurrent rmmod & shutdown illegal! */
 242
 243 #define FULLSTOP_DONTSTOP 0     /* Normal operation. */
 244 #define FULLSTOP_SHUTDOWN 1     /* System shutdown with rcutorture running. */
 245 #define FULLSTOP_RMMOD    2     /* Normal rmmod of rcutorture. */
 246 static int fullstop = FULLSTOP_RMMOD;
 247 /*
 248  * Protect fullstop transitions and spawning of kthreads.
 249  */
 250 static DEFINE_MUTEX(fullstop_mutex);
 251
 252 /* Forward reference. */
 253 static void rcu_torture_cleanup(void);
 254
 255 /*
 256  * Detect and respond to a system shutdown.
 257  */
 258 static int
 259 rcutorture_shutdown_notify(struct notifier_block *unused1,
 260                            unsigned long unused2, void *unused3)
 261 {
 262         mutex_lock(&fullstop_mutex);
 263         if (fullstop == FULLSTOP_DONTSTOP)
 264                 fullstop = FULLSTOP_SHUTDOWN;
 265         else
 266                 pr_warn(/* but going down anyway, so... */
 267                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
 268         mutex_unlock(&fullstop_mutex);
 269         return NOTIFY_DONE;
 270 }
 271
 272 /*
 273  * Absorb kthreads into a kernel function that won't return, so that
 274  * they won't ever access module text or data again.
 275  */
 276 static void rcutorture_shutdown_absorb(const char *title)
 277 {
 278         if (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
 279                 pr_notice(
 280                        "rcutorture thread %s parking due to system shutdown\n",
 281                        title);
 282                 schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
 283         }
 284 }
 285
 286 /*
 287  * Allocate an element from the rcu_tortures pool.
 288  */
 289 static struct rcu_torture *
 290 rcu_torture_alloc(void)
 291 {
 292         struct list_head *p;
 293
 294         spin_lock_bh(&rcu_torture_lock);
 295         if (list_empty(&rcu_torture_freelist)) {
 296                 atomic_inc(&n_rcu_torture_alloc_fail);
 297                 spin_unlock_bh(&rcu_torture_lock);
 298                 return NULL;
 299         }
 300         atomic_inc(&n_rcu_torture_alloc);
 301         p = rcu_torture_freelist.next;
 302         list_del_init(p);
 303         spin_unlock_bh(&rcu_torture_lock);
 304         return container_of(p, struct rcu_torture, rtort_free);
 305 }
 306
 307 /*
 308  * Free an element to the rcu_tortures pool.
 309  */
 310 static void
 311 rcu_torture_free(struct rcu_torture *p)
 312 {
 313         atomic_inc(&n_rcu_torture_free);
 314         spin_lock_bh(&rcu_torture_lock);
 315         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 316         spin_unlock_bh(&rcu_torture_lock);
 317 }
 318
 319 struct rcu_random_state {
 320         unsigned long rrs_state;
 321         long rrs_count;
 322 };
 323
 324 #define RCU_RANDOM_MULT 39916801  /* prime */
 325 #define RCU_RANDOM_ADD  479001701 /* prime */
 326 #define RCU_RANDOM_REFRESH 10000
 327
 328 #define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
 329
 330 /*
 331  * Crude but fast random-number generator.  Uses a linear congruential
 332  * generator, with occasional help from cpu_clock().
 333  */
 334 static unsigned long
 335 rcu_random(struct rcu_random_state *rrsp)
 336 {
 337         if (--rrsp->rrs_count < 0) {
 338                 rrsp->rrs_state += (unsigned long)local_clock();
 339                 rrsp->rrs_count = RCU_RANDOM_REFRESH;
 340         }
 341         rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
 342         return swahw32(rrsp->rrs_state);
 343 }
 344
 345 static void
 346 rcu_stutter_wait(const char *title)
 347 {
 348         while (stutter_pause_test || !rcutorture_runnable) {
 349                 if (rcutorture_runnable)
 350                         schedule_timeout_interruptible(1);
 351                 else
 352                         schedule_timeout_interruptible(round_jiffies_relative(HZ));
 353                 rcutorture_shutdown_absorb(title);
 354         }
 355 }
 356
 357 /*
 358  * Operations vector for selecting different types of tests.
 359  */
 360
 361 struct rcu_torture_ops {
 362         void (*init)(void);
 363         int (*readlock)(void);
 364         void (*read_delay)(struct rcu_random_state *rrsp);
 365         void (*readunlock)(int idx);
 366         int (*completed)(void);
 367         void (*deferred_free)(struct rcu_torture *p);
 368         void (*sync)(void);
 369         void (*exp_sync)(void);
 370         void (*call)(struct rcu_head *head, void (*func)(struct rcu_head *rcu));
 371         void (*cb_barrier)(void);
 372         void (*fqs)(void);
 373         int (*stats)(char *page);
 374         int irq_capable;
 375         int can_boost;
 376         const char *name;
 377 };
 378
 379 static struct rcu_torture_ops *cur_ops;
 380
 381 /*
 382  * Definitions for rcu torture testing.
 383  */
 384
 385 static int rcu_torture_read_lock(void) __acquires(RCU)
 386 {
 387         rcu_read_lock();
 388         return 0;
 389 }
 390
 391 static void rcu_read_delay(struct rcu_random_state *rrsp)
 392 {
 393         const unsigned long shortdelay_us = 200;
 394         const unsigned long longdelay_ms = 50;
 395
 396         /* We want a short delay sometimes to make a reader delay the grace
 397          * period, and we want a long delay occasionally to trigger
 398          * force_quiescent_state. */
 399
 400         if (!(rcu_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
 401                 mdelay(longdelay_ms);
 402         if (!(rcu_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
 403                 udelay(shortdelay_us);
 404 #ifdef CONFIG_PREEMPT
 405         if (!preempt_count() && !(rcu_random(rrsp) % (nrealreaders * 20000)))
 406                 preempt_schedule();  /* No QS if preempt_disable() in effect */
 407 #endif
 408 }
 409
 410 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 411 {
 412         rcu_read_unlock();
 413 }
 414
 415 static int rcu_torture_completed(void)
 416 {
 417         return rcu_batches_completed();
 418 }
 419
 420 static void
 421 rcu_torture_cb(struct rcu_head *p)
 422 {
 423         int i;
 424         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 425
 426         if (fullstop != FULLSTOP_DONTSTOP) {
 427                 /* Test is ending, just drop callbacks on the floor. */
 428                 /* The next initialization will pick up the pieces. */
 429                 return;
 430         }
 431         i = rp->rtort_pipe_count;
 432         if (i > RCU_TORTURE_PIPE_LEN)
 433                 i = RCU_TORTURE_PIPE_LEN;
 434         atomic_inc(&rcu_torture_wcount[i]);
 435         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 436                 rp->rtort_mbtest = 0;
 437                 rcu_torture_free(rp);
 438         } else {
 439                 cur_ops->deferred_free(rp);
 440         }
 441 }
 442
 443 static int rcu_no_completed(void)
 444 {
 445         return 0;
 446 }
 447
 448 static void rcu_torture_deferred_free(struct rcu_torture *p)
 449 {
 450         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 451 }
 452
 453 static void rcu_sync_torture_init(void)
 454 {
 455         INIT_LIST_HEAD(&rcu_torture_removed);
 456 }
 457
 458 static struct rcu_torture_ops rcu_ops = {
 459         .init           = rcu_sync_torture_init,
 460         .readlock       = rcu_torture_read_lock,
 461         .read_delay     = rcu_read_delay,
 462         .readunlock     = rcu_torture_read_unlock,
 463         .completed      = rcu_torture_completed,
 464         .deferred_free  = rcu_torture_deferred_free,
 465         .sync           = synchronize_rcu,
 466         .exp_sync       = synchronize_rcu_expedited,
 467         .call           = call_rcu,
 468         .cb_barrier     = rcu_barrier,
 469         .fqs            = rcu_force_quiescent_state,
 470         .stats          = NULL,
 471         .irq_capable    = 1,
 472         .can_boost      = rcu_can_boost(),
 473         .name           = "rcu"
 474 };
 475
 476 /*
 477  * Definitions for rcu_bh torture testing.
 478  */
 479
 480 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
 481 {
 482         rcu_read_lock_bh();
 483         return 0;
 484 }
 485
 486 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
 487 {
 488         rcu_read_unlock_bh();
 489 }
 490
 491 static int rcu_bh_torture_completed(void)
 492 {
 493         return rcu_batches_completed_bh();
 494 }
 495
 496 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 497 {
 498         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
 499 }
 500
 501 static struct rcu_torture_ops rcu_bh_ops = {
 502         .init           = rcu_sync_torture_init,
 503         .readlock       = rcu_bh_torture_read_lock,
 504         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 505         .readunlock     = rcu_bh_torture_read_unlock,
 506         .completed      = rcu_bh_torture_completed,
 507         .deferred_free  = rcu_bh_torture_deferred_free,
 508         .sync           = synchronize_rcu_bh,
 509         .exp_sync       = synchronize_rcu_bh_expedited,
 510         .call           = call_rcu_bh,
 511         .cb_barrier     = rcu_barrier_bh,
 512         .fqs            = rcu_bh_force_quiescent_state,
 513         .stats          = NULL,
 514         .irq_capable    = 1,
 515         .name           = "rcu_bh"
 516 };
 517
 518 /*
 519  * Definitions for srcu torture testing.
 520  */
 521
 522 DEFINE_STATIC_SRCU(srcu_ctl);
 523
 524 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
 525 {
 526         return srcu_read_lock(&srcu_ctl);
 527 }
 528
 529 static void srcu_read_delay(struct rcu_random_state *rrsp)
 530 {
 531         long delay;
 532         const long uspertick = 1000000 / HZ;
 533         const long longdelay = 10;
 534
 535         /* We want there to be long-running readers, but not all the time. */
 536
 537         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
 538         if (!delay)
 539                 schedule_timeout_interruptible(longdelay);
 540         else
 541                 rcu_read_delay(rrsp);
 542 }
 543
 544 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
 545 {
 546         srcu_read_unlock(&srcu_ctl, idx);
 547 }
 548
 549 static int srcu_torture_completed(void)
 550 {
 551         return srcu_batches_completed(&srcu_ctl);
 552 }
 553
 554 static void srcu_torture_deferred_free(struct rcu_torture *rp)
 555 {
 556         call_srcu(&srcu_ctl, &rp->rtort_rcu, rcu_torture_cb);
 557 }
 558
 559 static void srcu_torture_synchronize(void)
 560 {
 561         synchronize_srcu(&srcu_ctl);
 562 }
 563
 564 static void srcu_torture_call(struct rcu_head *head,
 565                               void (*func)(struct rcu_head *head))
 566 {
 567         call_srcu(&srcu_ctl, head, func);
 568 }
 569
 570 static void srcu_torture_barrier(void)
 571 {
 572         srcu_barrier(&srcu_ctl);
 573 }
 574
 575 static int srcu_torture_stats(char *page)
 576 {
 577         int cnt = 0;
 578         int cpu;
 579         int idx = srcu_ctl.completed & 0x1;
 580
 581         cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
 582                        torture_type, TORTURE_FLAG, idx);
 583         for_each_possible_cpu(cpu) {
 584                 cnt += sprintf(&page[cnt], " %d(%lu,%lu)", cpu,
 585                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
 586                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
 587         }
 588         cnt += sprintf(&page[cnt], "\n");
 589         return cnt;
 590 }
 591
 592 static void srcu_torture_synchronize_expedited(void)
 593 {
 594         synchronize_srcu_expedited(&srcu_ctl);
 595 }
 596
 597 static struct rcu_torture_ops srcu_ops = {
 598         .init           = rcu_sync_torture_init,
 599         .readlock       = srcu_torture_read_lock,
 600         .read_delay     = srcu_read_delay,
 601         .readunlock     = srcu_torture_read_unlock,
 602         .completed      = srcu_torture_completed,
 603         .deferred_free  = srcu_torture_deferred_free,
 604         .sync           = srcu_torture_synchronize,
 605         .exp_sync       = srcu_torture_synchronize_expedited,
 606         .call           = srcu_torture_call,
 607         .cb_barrier     = srcu_torture_barrier,
 608         .stats          = srcu_torture_stats,
 609         .name           = "srcu"
 610 };
 611
 612 /*
 613  * Definitions for sched torture testing.
 614  */
 615
 616 static int sched_torture_read_lock(void)
 617 {
 618         preempt_disable();
 619         return 0;
 620 }
 621
 622 static void sched_torture_read_unlock(int idx)
 623 {
 624         preempt_enable();
 625 }
 626
 627 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
 628 {
 629         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
 630 }
 631
 632 static struct rcu_torture_ops sched_ops = {
 633         .init           = rcu_sync_torture_init,
 634         .readlock       = sched_torture_read_lock,
 635         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 636         .readunlock     = sched_torture_read_unlock,
 637         .completed      = rcu_no_completed,
 638         .deferred_free  = rcu_sched_torture_deferred_free,
 639         .sync           = synchronize_sched,
 640         .exp_sync       = synchronize_sched_expedited,
 641         .call           = call_rcu_sched,
 642         .cb_barrier     = rcu_barrier_sched,
 643         .fqs            = rcu_sched_force_quiescent_state,
 644         .stats          = NULL,
 645         .irq_capable    = 1,
 646         .name           = "sched"
 647 };
 648
 649 /*
 650  * RCU torture priority-boost testing.  Runs one real-time thread per
 651  * CPU for moderate bursts, repeatedly registering RCU callbacks and
 652  * spinning waiting for them to be invoked.  If a given callback takes
 653  * too long to be invoked, we assume that priority inversion has occurred.
 654  */
 655
 656 struct rcu_boost_inflight {
 657         struct rcu_head rcu;
 658         int inflight;
 659 };
 660
 661 static void rcu_torture_boost_cb(struct rcu_head *head)
 662 {
 663         struct rcu_boost_inflight *rbip =
 664                 container_of(head, struct rcu_boost_inflight, rcu);
 665
 666         smp_mb(); /* Ensure RCU-core accesses precede clearing ->inflight */
 667         rbip->inflight = 0;
 668 }
 669
 670 static int rcu_torture_boost(void *arg)
 671 {
 672         unsigned long call_rcu_time;
 673         unsigned long endtime;
 674         unsigned long oldstarttime;
 675         struct rcu_boost_inflight rbi = { .inflight = 0 };
 676         struct sched_param sp;
 677
 678         VERBOSE_PRINTK_STRING("rcu_torture_boost started");
 679
 680         /* Set real-time priority. */
 681         sp.sched_priority = 1;
 682         if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 683                 VERBOSE_PRINTK_STRING("rcu_torture_boost RT prio failed!");
 684                 n_rcu_torture_boost_rterror++;
 685         }
 686
 687         init_rcu_head_on_stack(&rbi.rcu);
 688         /* Each pass through the following loop does one boost-test cycle. */
 689         do {
 690                 /* Wait for the next test interval. */
 691                 oldstarttime = boost_starttime;
 692                 while (ULONG_CMP_LT(jiffies, oldstarttime)) {
 693                         schedule_timeout_interruptible(oldstarttime - jiffies);
 694                         rcu_stutter_wait("rcu_torture_boost");
 695                         if (kthread_should_stop() ||
 696                             fullstop != FULLSTOP_DONTSTOP)
 697                                 goto checkwait;
 698                 }
 699
 700                 /* Do one boost-test interval. */
 701                 endtime = oldstarttime + test_boost_duration * HZ;
 702                 call_rcu_time = jiffies;
 703                 while (ULONG_CMP_LT(jiffies, endtime)) {
 704                         /* If we don't have a callback in flight, post one. */
 705                         if (!rbi.inflight) {
 706                                 smp_mb(); /* RCU core before ->inflight = 1. */
 707                                 rbi.inflight = 1;
 708                                 call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 709                                 if (jiffies - call_rcu_time >
 710                                          test_boost_duration * HZ - HZ / 2) {
 711                                         VERBOSE_PRINTK_STRING("rcu_torture_boost boosting failed");
 712                                         n_rcu_torture_boost_failure++;
 713                                 }
 714                                 call_rcu_time = jiffies;
 715                         }
 716                         cond_resched();
 717                         rcu_stutter_wait("rcu_torture_boost");
 718                         if (kthread_should_stop() ||
 719                             fullstop != FULLSTOP_DONTSTOP)
 720                                 goto checkwait;
 721                 }
 722
 723                 /*
 724                  * Set the start time of the next test interval.
 725                  * Yes, this is vulnerable to long delays, but such
 726                  * delays simply cause a false negative for the next
 727                  * interval.  Besides, we are running at RT priority,
 728                  * so delays should be relatively rare.
 729                  */
 730                 while (oldstarttime == boost_starttime &&
 731                        !kthread_should_stop()) {
 732                         if (mutex_trylock(&boost_mutex)) {
 733                                 boost_starttime = jiffies +
 734                                                   test_boost_interval * HZ;
 735                                 n_rcu_torture_boosts++;
 736                                 mutex_unlock(&boost_mutex);
 737                                 break;
 738                         }
 739                         schedule_timeout_uninterruptible(1);
 740                 }
 741
 742                 /* Go do the stutter. */
 743 checkwait:      rcu_stutter_wait("rcu_torture_boost");
 744         } while (!kthread_should_stop() && fullstop  == FULLSTOP_DONTSTOP);
 745
 746         /* Clean up and exit. */
 747         VERBOSE_PRINTK_STRING("rcu_torture_boost task stopping");
 748         rcutorture_shutdown_absorb("rcu_torture_boost");
 749         while (!kthread_should_stop() || rbi.inflight)
 750                 schedule_timeout_uninterruptible(1);
 751         smp_mb(); /* order accesses to ->inflight before stack-frame death. */
 752         destroy_rcu_head_on_stack(&rbi.rcu);
 753         return 0;
 754 }
 755
 756 /*
 757  * RCU torture force-quiescent-state kthread.  Repeatedly induces
 758  * bursts of calls to force_quiescent_state(), increasing the probability
 759  * of occurrence of some important types of race conditions.
 760  */
 761 static int
 762 rcu_torture_fqs(void *arg)
 763 {
 764         unsigned long fqs_resume_time;
 765         int fqs_burst_remaining;
 766
 767         VERBOSE_PRINTK_STRING("rcu_torture_fqs task started");
 768         do {
 769                 fqs_resume_time = jiffies + fqs_stutter * HZ;
 770                 while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
 771                        !kthread_should_stop()) {
 772                         schedule_timeout_interruptible(1);
 773                 }
 774                 fqs_burst_remaining = fqs_duration;
 775                 while (fqs_burst_remaining > 0 &&
 776                        !kthread_should_stop()) {
 777                         cur_ops->fqs();
 778                         udelay(fqs_holdoff);
 779                         fqs_burst_remaining -= fqs_holdoff;
 780                 }
 781                 rcu_stutter_wait("rcu_torture_fqs");
 782         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 783         VERBOSE_PRINTK_STRING("rcu_torture_fqs task stopping");
 784         rcutorture_shutdown_absorb("rcu_torture_fqs");
 785         while (!kthread_should_stop())
 786                 schedule_timeout_uninterruptible(1);
 787         return 0;
 788 }
 789
 790 /*
 791  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 792  * for that pointed to by rcu_torture_current, freeing the old structure
 793  * after a series of grace periods (the "pipeline").
 794  */
 795 static int
 796 rcu_torture_writer(void *arg)
 797 {
 798         bool exp;
 799         int i;
 800         struct rcu_torture *rp;
 801         struct rcu_torture *rp1;
 802         struct rcu_torture *old_rp;
 803         static DEFINE_RCU_RANDOM(rand);
 804
 805         VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
 806         set_user_nice(current, 19);
 807
 808         do {
 809                 schedule_timeout_uninterruptible(1);
 810                 rp = rcu_torture_alloc();
 811                 if (rp == NULL)
 812                         continue;
 813                 rp->rtort_pipe_count = 0;
 814                 udelay(rcu_random(&rand) & 0x3ff);
 815                 old_rp = rcu_dereference_check(rcu_torture_current,
 816                                                current == writer_task);
 817                 rp->rtort_mbtest = 1;
 818                 rcu_assign_pointer(rcu_torture_current, rp);
 819                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
 820                 if (old_rp) {
 821                         i = old_rp->rtort_pipe_count;
 822                         if (i > RCU_TORTURE_PIPE_LEN)
 823                                 i = RCU_TORTURE_PIPE_LEN;
 824                         atomic_inc(&rcu_torture_wcount[i]);
 825                         old_rp->rtort_pipe_count++;
 826                         if (gp_normal == gp_exp)
 827                                 exp = !!(rcu_random(&rand) & 0x80);
 828                         else
 829                                 exp = gp_exp;
 830                         if (!exp) {
 831                                 cur_ops->deferred_free(old_rp);
 832                         } else {
 833                                 cur_ops->exp_sync();
 834                                 list_add(&old_rp->rtort_free,
 835                                          &rcu_torture_removed);
 836                                 list_for_each_entry_safe(rp, rp1,
 837                                                          &rcu_torture_removed,
 838                                                          rtort_free) {
 839                                         i = rp->rtort_pipe_count;
 840                                         if (i > RCU_TORTURE_PIPE_LEN)
 841                                                 i = RCU_TORTURE_PIPE_LEN;
 842                                         atomic_inc(&rcu_torture_wcount[i]);
 843                                         if (++rp->rtort_pipe_count >=
 844                                             RCU_TORTURE_PIPE_LEN) {
 845                                                 rp->rtort_mbtest = 0;
 846                                                 list_del(&rp->rtort_free);
 847                                                 rcu_torture_free(rp);
 848                                         }
 849                                  }
 850                         }
 851                 }
 852                 rcutorture_record_progress(++rcu_torture_current_version);
 853                 rcu_stutter_wait("rcu_torture_writer");
 854         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 855         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
 856         rcutorture_shutdown_absorb("rcu_torture_writer");
 857         while (!kthread_should_stop())
 858                 schedule_timeout_uninterruptible(1);
 859         return 0;
 860 }
 861
 862 /*
 863  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
 864  * delay between calls.
 865  */
 866 static int
 867 rcu_torture_fakewriter(void *arg)
 868 {
 869         DEFINE_RCU_RANDOM(rand);
 870
 871         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
 872         set_user_nice(current, 19);
 873
 874         do {
 875                 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
 876                 udelay(rcu_random(&rand) & 0x3ff);
 877                 if (cur_ops->cb_barrier != NULL &&
 878                     rcu_random(&rand) % (nfakewriters * 8) == 0) {
 879                         cur_ops->cb_barrier();
 880                 } else if (gp_normal == gp_exp) {
 881                         if (rcu_random(&rand) & 0x80)
 882                                 cur_ops->sync();
 883                         else
 884                                 cur_ops->exp_sync();
 885                 } else if (gp_normal) {
 886                         cur_ops->sync();
 887                 } else {
 888                         cur_ops->exp_sync();
 889                 }
 890                 rcu_stutter_wait("rcu_torture_fakewriter");
 891         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 892
 893         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
 894         rcutorture_shutdown_absorb("rcu_torture_fakewriter");
 895         while (!kthread_should_stop())
 896                 schedule_timeout_uninterruptible(1);
 897         return 0;
 898 }
 899
 900 void rcutorture_trace_dump(void)
 901 {
 902         static atomic_t beenhere = ATOMIC_INIT(0);
 903
 904         if (atomic_read(&beenhere))
 905                 return;
 906         if (atomic_xchg(&beenhere, 1) != 0)
 907                 return;
 908         ftrace_dump(DUMP_ALL);
 909 }
 910
 911 /*
 912  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
 913  * incrementing the corresponding element of the pipeline array.  The
 914  * counter in the element should never be greater than 1, otherwise, the
 915  * RCU implementation is broken.
 916  */
 917 static void rcu_torture_timer(unsigned long unused)
 918 {
 919         int idx;
 920         int completed;
 921         int completed_end;
 922         static DEFINE_RCU_RANDOM(rand);
 923         static DEFINE_SPINLOCK(rand_lock);
 924         struct rcu_torture *p;
 925         int pipe_count;
 926         unsigned long long ts;
 927
 928         idx = cur_ops->readlock();
 929         completed = cur_ops->completed();
 930         ts = rcu_trace_clock_local();
 931         p = rcu_dereference_check(rcu_torture_current,
 932                                   rcu_read_lock_bh_held() ||
 933                                   rcu_read_lock_sched_held() ||
 934                                   srcu_read_lock_held(&srcu_ctl));
 935         if (p == NULL) {
 936                 /* Leave because rcu_torture_writer is not yet underway */
 937                 cur_ops->readunlock(idx);
 938                 return;
 939         }
 940         if (p->rtort_mbtest == 0)
 941                 atomic_inc(&n_rcu_torture_mberror);
 942         spin_lock(&rand_lock);
 943         cur_ops->read_delay(&rand);
 944         n_rcu_torture_timers++;
 945         spin_unlock(&rand_lock);
 946         preempt_disable();
 947         pipe_count = p->rtort_pipe_count;
 948         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
 949                 /* Should not happen, but... */
 950                 pipe_count = RCU_TORTURE_PIPE_LEN;
 951         }
 952         completed_end = cur_ops->completed();
 953         if (pipe_count > 1) {
 954                 do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu, ts,
 955                                           completed, completed_end);
 956                 rcutorture_trace_dump();
 957         }
 958         __this_cpu_inc(rcu_torture_count[pipe_count]);
 959         completed = completed_end - completed;
 960         if (completed > RCU_TORTURE_PIPE_LEN) {
 961                 /* Should not happen, but... */
 962                 completed = RCU_TORTURE_PIPE_LEN;
 963         }
 964         __this_cpu_inc(rcu_torture_batch[completed]);
 965         preempt_enable();
 966         cur_ops->readunlock(idx);
 967 }
 968
 969 /*
 970  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
 971  * incrementing the corresponding element of the pipeline array.  The
 972  * counter in the element should never be greater than 1, otherwise, the
 973  * RCU implementation is broken.
 974  */
 975 static int
 976 rcu_torture_reader(void *arg)
 977 {
 978         int completed;
 979         int completed_end;
 980         int idx;
 981         DEFINE_RCU_RANDOM(rand);
 982         struct rcu_torture *p;
 983         int pipe_count;
 984         struct timer_list t;
 985         unsigned long long ts;
 986
 987         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
 988         set_user_nice(current, 19);
 989         if (irqreader && cur_ops->irq_capable)
 990                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
 991
 992         do {
 993                 if (irqreader && cur_ops->irq_capable) {
 994                         if (!timer_pending(&t))
 995                                 mod_timer(&t, jiffies + 1);
 996                 }
 997                 idx = cur_ops->readlock();
 998                 completed = cur_ops->completed();
 999                 ts = rcu_trace_clock_local();
1000                 p = rcu_dereference_check(rcu_torture_current,
1001                                           rcu_read_lock_bh_held() ||
1002                                           rcu_read_lock_sched_held() ||
1003                                           srcu_read_lock_held(&srcu_ctl));
1004                 if (p == NULL) {
1005                         /* Wait for rcu_torture_writer to get underway */
1006                         cur_ops->readunlock(idx);
1007                         schedule_timeout_interruptible(HZ);
1008                         continue;
1009                 }
1010                 if (p->rtort_mbtest == 0)
1011                         atomic_inc(&n_rcu_torture_mberror);
1012                 cur_ops->read_delay(&rand);
1013                 preempt_disable();
1014                 pipe_count = p->rtort_pipe_count;
1015                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1016                         /* Should not happen, but... */
1017                         pipe_count = RCU_TORTURE_PIPE_LEN;
1018                 }
1019                 completed_end = cur_ops->completed();
1020                 if (pipe_count > 1) {
1021                         do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
1022                                                   ts, completed, completed_end);
1023                         rcutorture_trace_dump();
1024                 }
1025                 __this_cpu_inc(rcu_torture_count[pipe_count]);
1026                 completed = completed_end - completed;
1027                 if (completed > RCU_TORTURE_PIPE_LEN) {
1028                         /* Should not happen, but... */
1029                         completed = RCU_TORTURE_PIPE_LEN;
1030                 }
1031                 __this_cpu_inc(rcu_torture_batch[completed]);
1032                 preempt_enable();
1033                 cur_ops->readunlock(idx);
1034                 schedule();
1035                 rcu_stutter_wait("rcu_torture_reader");
1036         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1037         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
1038         rcutorture_shutdown_absorb("rcu_torture_reader");
1039         if (irqreader && cur_ops->irq_capable)
1040                 del_timer_sync(&t);
1041         while (!kthread_should_stop())
1042                 schedule_timeout_uninterruptible(1);
1043         return 0;
1044 }
1045
1046 /*
1047  * Create an RCU-torture statistics message in the specified buffer.
1048  */
1049 static int
1050 rcu_torture_printk(char *page)
1051 {
1052         int cnt = 0;
1053         int cpu;
1054         int i;
1055         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1056         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1057
1058         for_each_possible_cpu(cpu) {
1059                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1060                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1061                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1062                 }
1063         }
1064         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1065                 if (pipesummary[i] != 0)
1066                         break;
1067         }
1068         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
1069         cnt += sprintf(&page[cnt],
1070                        "rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
1071                        rcu_torture_current,
1072                        rcu_torture_current_version,
1073                        list_empty(&rcu_torture_freelist),
1074                        atomic_read(&n_rcu_torture_alloc),
1075                        atomic_read(&n_rcu_torture_alloc_fail),
1076                        atomic_read(&n_rcu_torture_free));
1077         cnt += sprintf(&page[cnt], "rtmbe: %d rtbke: %ld rtbre: %ld ",
1078                        atomic_read(&n_rcu_torture_mberror),
1079                        n_rcu_torture_boost_ktrerror,
1080                        n_rcu_torture_boost_rterror);
1081         cnt += sprintf(&page[cnt], "rtbf: %ld rtb: %ld nt: %ld ",
1082                        n_rcu_torture_boost_failure,
1083                        n_rcu_torture_boosts,
1084                        n_rcu_torture_timers);
1085         cnt += sprintf(&page[cnt],
1086                        "onoff: %ld/%ld:%ld/%ld %d,%d:%d,%d %lu:%lu (HZ=%d) ",
1087                        n_online_successes, n_online_attempts,
1088                        n_offline_successes, n_offline_attempts,
1089                        min_online, max_online,
1090                        min_offline, max_offline,
1091                        sum_online, sum_offline, HZ);
1092         cnt += sprintf(&page[cnt], "barrier: %ld/%ld:%ld",
1093                        n_barrier_successes,
1094                        n_barrier_attempts,
1095                        n_rcu_torture_barrier_error);
1096         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1097         if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1098             n_rcu_torture_barrier_error != 0 ||
1099             n_rcu_torture_boost_ktrerror != 0 ||
1100             n_rcu_torture_boost_rterror != 0 ||
1101             n_rcu_torture_boost_failure != 0 ||
1102             i > 1) {
1103                 cnt += sprintf(&page[cnt], "!!! ");
1104                 atomic_inc(&n_rcu_torture_error);
1105                 WARN_ON_ONCE(1);
1106         }
1107         cnt += sprintf(&page[cnt], "Reader Pipe: ");
1108         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1109                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
1110         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1111         cnt += sprintf(&page[cnt], "Reader Batch: ");
1112         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1113                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
1114         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1115         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
1116         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1117                 cnt += sprintf(&page[cnt], " %d",
1118                                atomic_read(&rcu_torture_wcount[i]));
1119         }
1120         cnt += sprintf(&page[cnt], "\n");
1121         if (cur_ops->stats)
1122                 cnt += cur_ops->stats(&page[cnt]);
1123         return cnt;
1124 }
1125
1126 /*
1127  * Print torture statistics.  Caller must ensure that there is only
1128  * one call to this function at a given time!!!  This is normally
1129  * accomplished by relying on the module system to only have one copy
1130  * of the module loaded, and then by giving the rcu_torture_stats
1131  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1132  * thread is not running).
1133  */
1134 static void
1135 rcu_torture_stats_print(void)
1136 {
1137         int cnt;
1138
1139         cnt = rcu_torture_printk(printk_buf);
1140         pr_alert("%s", printk_buf);
1141 }
1142
1143 /*
1144  * Periodically prints torture statistics, if periodic statistics printing
1145  * was specified via the stat_interval module parameter.
1146  *
1147  * No need to worry about fullstop here, since this one doesn't reference
1148  * volatile state or register callbacks.
1149  */
1150 static int
1151 rcu_torture_stats(void *arg)
1152 {
1153         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
1154         do {
1155                 schedule_timeout_interruptible(stat_interval * HZ);
1156                 rcu_torture_stats_print();
1157                 rcutorture_shutdown_absorb("rcu_torture_stats");
1158         } while (!kthread_should_stop());
1159         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
1160         return 0;
1161 }
1162
1163 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
1164
1165 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
1166  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
1167  */
1168 static void rcu_torture_shuffle_tasks(void)
1169 {
1170         int i;
1171
1172         cpumask_setall(shuffle_tmp_mask);
1173         get_online_cpus();
1174
1175         /* No point in shuffling if there is only one online CPU (ex: UP) */
1176         if (num_online_cpus() == 1) {
1177                 put_online_cpus();
1178                 return;
1179         }
1180
1181         if (rcu_idle_cpu != -1)
1182                 cpumask_clear_cpu(rcu_idle_cpu, shuffle_tmp_mask);
1183
1184         set_cpus_allowed_ptr(current, shuffle_tmp_mask);
1185
1186         if (reader_tasks) {
1187                 for (i = 0; i < nrealreaders; i++)
1188                         if (reader_tasks[i])
1189                                 set_cpus_allowed_ptr(reader_tasks[i],
1190                                                      shuffle_tmp_mask);
1191         }
1192         if (fakewriter_tasks) {
1193                 for (i = 0; i < nfakewriters; i++)
1194                         if (fakewriter_tasks[i])
1195                                 set_cpus_allowed_ptr(fakewriter_tasks[i],
1196                                                      shuffle_tmp_mask);
1197         }
1198         if (writer_task)
1199                 set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
1200         if (stats_task)
1201                 set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
1202         if (stutter_task)
1203                 set_cpus_allowed_ptr(stutter_task, shuffle_tmp_mask);
1204         if (fqs_task)
1205                 set_cpus_allowed_ptr(fqs_task, shuffle_tmp_mask);
1206         if (shutdown_task)
1207                 set_cpus_allowed_ptr(shutdown_task, shuffle_tmp_mask);
1208 #ifdef CONFIG_HOTPLUG_CPU
1209         if (onoff_task)
1210                 set_cpus_allowed_ptr(onoff_task, shuffle_tmp_mask);
1211 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
1212         if (stall_task)
1213                 set_cpus_allowed_ptr(stall_task, shuffle_tmp_mask);
1214         if (barrier_cbs_tasks)
1215                 for (i = 0; i < n_barrier_cbs; i++)
1216                         if (barrier_cbs_tasks[i])
1217                                 set_cpus_allowed_ptr(barrier_cbs_tasks[i],
1218                                                      shuffle_tmp_mask);
1219         if (barrier_task)
1220                 set_cpus_allowed_ptr(barrier_task, shuffle_tmp_mask);
1221
1222         if (rcu_idle_cpu == -1)
1223                 rcu_idle_cpu = num_online_cpus() - 1;
1224         else
1225                 rcu_idle_cpu--;
1226
1227         put_online_cpus();
1228 }
1229
1230 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
1231  * system to become idle at a time and cut off its timer ticks. This is meant
1232  * to test the support for such tickless idle CPU in RCU.
1233  */
1234 static int
1235 rcu_torture_shuffle(void *arg)
1236 {
1237         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
1238         do {
1239                 schedule_timeout_interruptible(shuffle_interval * HZ);
1240                 rcu_torture_shuffle_tasks();
1241                 rcutorture_shutdown_absorb("rcu_torture_shuffle");
1242         } while (!kthread_should_stop());
1243         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
1244         return 0;
1245 }
1246
1247 /* Cause the rcutorture test to "stutter", starting and stopping all
1248  * threads periodically.
1249  */
1250 static int
1251 rcu_torture_stutter(void *arg)
1252 {
1253         VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
1254         do {
1255                 schedule_timeout_interruptible(stutter * HZ);
1256                 stutter_pause_test = 1;
1257                 if (!kthread_should_stop())
1258                         schedule_timeout_interruptible(stutter * HZ);
1259                 stutter_pause_test = 0;
1260                 rcutorture_shutdown_absorb("rcu_torture_stutter");
1261         } while (!kthread_should_stop());
1262         VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
1263         return 0;
1264 }
1265
1266 static inline void
1267 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
1268 {
1269         pr_alert("%s" TORTURE_FLAG
1270                  "--- %s: nreaders=%d nfakewriters=%d "
1271                  "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1272                  "shuffle_interval=%d stutter=%d irqreader=%d "
1273                  "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1274                  "test_boost=%d/%d test_boost_interval=%d "
1275                  "test_boost_duration=%d shutdown_secs=%d "
1276                  "stall_cpu=%d stall_cpu_holdoff=%d "
1277                  "n_barrier_cbs=%d "
1278                  "onoff_interval=%d onoff_holdoff=%d\n",
1279                  torture_type, tag, nrealreaders, nfakewriters,
1280                  stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1281                  stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1282                  test_boost, cur_ops->can_boost,
1283                  test_boost_interval, test_boost_duration, shutdown_secs,
1284                  stall_cpu, stall_cpu_holdoff,
1285                  n_barrier_cbs,
1286                  onoff_interval, onoff_holdoff);
1287 }
1288
1289 static struct notifier_block rcutorture_shutdown_nb = {
1290         .notifier_call = rcutorture_shutdown_notify,
1291 };
1292
1293 static void rcutorture_booster_cleanup(int cpu)
1294 {
1295         struct task_struct *t;
1296
1297         if (boost_tasks[cpu] == NULL)
1298                 return;
1299         mutex_lock(&boost_mutex);
1300         VERBOSE_PRINTK_STRING("Stopping rcu_torture_boost task");
1301         t = boost_tasks[cpu];
1302         boost_tasks[cpu] = NULL;
1303         mutex_unlock(&boost_mutex);
1304
1305         /* This must be outside of the mutex, otherwise deadlock! */
1306         kthread_stop(t);
1307         boost_tasks[cpu] = NULL;
1308 }
1309
1310 static int rcutorture_booster_init(int cpu)
1311 {
1312         int retval;
1313
1314         if (boost_tasks[cpu] != NULL)
1315                 return 0;  /* Already created, nothing more to do. */
1316
1317         /* Don't allow time recalculation while creating a new task. */
1318         mutex_lock(&boost_mutex);
1319         VERBOSE_PRINTK_STRING("Creating rcu_torture_boost task");
1320         boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1321                                                   cpu_to_node(cpu),
1322                                                   "rcu_torture_boost");
1323         if (IS_ERR(boost_tasks[cpu])) {
1324                 retval = PTR_ERR(boost_tasks[cpu]);
1325                 VERBOSE_PRINTK_STRING("rcu_torture_boost task create failed");
1326                 n_rcu_torture_boost_ktrerror++;
1327                 boost_tasks[cpu] = NULL;
1328                 mutex_unlock(&boost_mutex);
1329                 return retval;
1330         }
1331         kthread_bind(boost_tasks[cpu], cpu);
1332         wake_up_process(boost_tasks[cpu]);
1333         mutex_unlock(&boost_mutex);
1334         return 0;
1335 }
1336
1337 /*
1338  * Cause the rcutorture test to shutdown the system after the test has
1339  * run for the time specified by the shutdown_secs module parameter.
1340  */
1341 static int
1342 rcu_torture_shutdown(void *arg)
1343 {
1344         long delta;
1345         unsigned long jiffies_snap;
1346
1347         VERBOSE_PRINTK_STRING("rcu_torture_shutdown task started");
1348         jiffies_snap = ACCESS_ONCE(jiffies);
1349         while (ULONG_CMP_LT(jiffies_snap, shutdown_time) &&
1350                !kthread_should_stop()) {
1351                 delta = shutdown_time - jiffies_snap;
1352                 if (verbose)
1353                         pr_alert("%s" TORTURE_FLAG
1354                                  "rcu_torture_shutdown task: %lu jiffies remaining\n",
1355                                  torture_type, delta);
1356                 schedule_timeout_interruptible(delta);
1357                 jiffies_snap = ACCESS_ONCE(jiffies);
1358         }
1359         if (kthread_should_stop()) {
1360                 VERBOSE_PRINTK_STRING("rcu_torture_shutdown task stopping");
1361                 return 0;
1362         }
1363
1364         /* OK, shut down the system. */
1365
1366         VERBOSE_PRINTK_STRING("rcu_torture_shutdown task shutting down system");
1367         shutdown_task = NULL;   /* Avoid self-kill deadlock. */
1368         rcu_torture_cleanup();  /* Get the success/failure message. */
1369         kernel_power_off();     /* Shut down the system. */
1370         return 0;
1371 }
1372
1373 #ifdef CONFIG_HOTPLUG_CPU
1374
1375 /*
1376  * Execute random CPU-hotplug operations at the interval specified
1377  * by the onoff_interval.
1378  */
1379 static int
1380 rcu_torture_onoff(void *arg)
1381 {
1382         int cpu;
1383         unsigned long delta;
1384         int maxcpu = -1;
1385         DEFINE_RCU_RANDOM(rand);
1386         int ret;
1387         unsigned long starttime;
1388
1389         VERBOSE_PRINTK_STRING("rcu_torture_onoff task started");
1390         for_each_online_cpu(cpu)
1391                 maxcpu = cpu;
1392         WARN_ON(maxcpu < 0);
1393         if (onoff_holdoff > 0) {
1394                 VERBOSE_PRINTK_STRING("rcu_torture_onoff begin holdoff");
1395                 schedule_timeout_interruptible(onoff_holdoff * HZ);
1396                 VERBOSE_PRINTK_STRING("rcu_torture_onoff end holdoff");
1397         }
1398         while (!kthread_should_stop()) {
1399                 cpu = (rcu_random(&rand) >> 4) % (maxcpu + 1);
1400                 if (cpu_online(cpu) && cpu_is_hotpluggable(cpu)) {
1401                         if (verbose)
1402                                 pr_alert("%s" TORTURE_FLAG
1403                                          "rcu_torture_onoff task: offlining %d\n",
1404                                          torture_type, cpu);
1405                         starttime = jiffies;
1406                         n_offline_attempts++;
1407                         ret = cpu_down(cpu);
1408                         if (ret) {
1409                                 if (verbose)
1410                                         pr_alert("%s" TORTURE_FLAG
1411                                                  "rcu_torture_onoff task: offline %d failed: errno %d\n",
1412                                                  torture_type, cpu, ret);
1413                         } else {
1414                                 if (verbose)
1415                                         pr_alert("%s" TORTURE_FLAG
1416                                                  "rcu_torture_onoff task: offlined %d\n",
1417                                                  torture_type, cpu);
1418                                 n_offline_successes++;
1419                                 delta = jiffies - starttime;
1420                                 sum_offline += delta;
1421                                 if (min_offline < 0) {
1422                                         min_offline = delta;
1423                                         max_offline = delta;
1424                                 }
1425                                 if (min_offline > delta)
1426                                         min_offline = delta;
1427                                 if (max_offline < delta)
1428                                         max_offline = delta;
1429                         }
1430                 } else if (cpu_is_hotpluggable(cpu)) {
1431                         if (verbose)
1432                                 pr_alert("%s" TORTURE_FLAG
1433                                          "rcu_torture_onoff task: onlining %d\n",
1434                                          torture_type, cpu);
1435                         starttime = jiffies;
1436                         n_online_attempts++;
1437                         ret = cpu_up(cpu);
1438                         if (ret) {
1439                                 if (verbose)
1440                                         pr_alert("%s" TORTURE_FLAG
1441                                                  "rcu_torture_onoff task: online %d failed: errno %d\n",
1442                                                  torture_type, cpu, ret);
1443                         } else {
1444                                 if (verbose)
1445                                         pr_alert("%s" TORTURE_FLAG
1446                                                  "rcu_torture_onoff task: onlined %d\n",
1447                                                  torture_type, cpu);
1448                                 n_online_successes++;
1449                                 delta = jiffies - starttime;
1450                                 sum_online += delta;
1451                                 if (min_online < 0) {
1452                                         min_online = delta;
1453                                         max_online = delta;
1454                                 }
1455                                 if (min_online > delta)
1456                                         min_online = delta;
1457                                 if (max_online < delta)
1458                                         max_online = delta;
1459                         }
1460                 }
1461                 schedule_timeout_interruptible(onoff_interval * HZ);
1462         }
1463         VERBOSE_PRINTK_STRING("rcu_torture_onoff task stopping");
1464         return 0;
1465 }
1466
1467 static int
1468 rcu_torture_onoff_init(void)
1469 {
1470         int ret;
1471
1472         if (onoff_interval <= 0)
1473                 return 0;
1474         onoff_task = kthread_run(rcu_torture_onoff, NULL, "rcu_torture_onoff");
1475         if (IS_ERR(onoff_task)) {
1476                 ret = PTR_ERR(onoff_task);
1477                 onoff_task = NULL;
1478                 return ret;
1479         }
1480         return 0;
1481 }
1482
1483 static void rcu_torture_onoff_cleanup(void)
1484 {
1485         if (onoff_task == NULL)
1486                 return;
1487         VERBOSE_PRINTK_STRING("Stopping rcu_torture_onoff task");
1488         kthread_stop(onoff_task);
1489         onoff_task = NULL;
1490 }
1491
1492 #else /* #ifdef CONFIG_HOTPLUG_CPU */
1493
1494 static int
1495 rcu_torture_onoff_init(void)
1496 {
1497         return 0;
1498 }
1499
1500 static void rcu_torture_onoff_cleanup(void)
1501 {
1502 }
1503
1504 #endif /* #else #ifdef CONFIG_HOTPLUG_CPU */
1505
1506 /*
1507  * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
1508  * induces a CPU stall for the time specified by stall_cpu.
1509  */
1510 static int rcu_torture_stall(void *args)
1511 {
1512         unsigned long stop_at;
1513
1514         VERBOSE_PRINTK_STRING("rcu_torture_stall task started");
1515         if (stall_cpu_holdoff > 0) {
1516                 VERBOSE_PRINTK_STRING("rcu_torture_stall begin holdoff");
1517                 schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1518                 VERBOSE_PRINTK_STRING("rcu_torture_stall end holdoff");
1519         }
1520         if (!kthread_should_stop()) {
1521                 stop_at = get_seconds() + stall_cpu;
1522                 /* RCU CPU stall is expected behavior in following code. */
1523                 pr_alert("rcu_torture_stall start.\n");
1524                 rcu_read_lock();
1525                 preempt_disable();
1526                 while (ULONG_CMP_LT(get_seconds(), stop_at))
1527                         continue;  /* Induce RCU CPU stall warning. */
1528                 preempt_enable();
1529                 rcu_read_unlock();
1530                 pr_alert("rcu_torture_stall end.\n");
1531         }
1532         rcutorture_shutdown_absorb("rcu_torture_stall");
1533         while (!kthread_should_stop())
1534                 schedule_timeout_interruptible(10 * HZ);
1535         return 0;
1536 }
1537
1538 /* Spawn CPU-stall kthread, if stall_cpu specified. */
1539 static int __init rcu_torture_stall_init(void)
1540 {
1541         int ret;
1542
1543         if (stall_cpu <= 0)
1544                 return 0;
1545         stall_task = kthread_run(rcu_torture_stall, NULL, "rcu_torture_stall");
1546         if (IS_ERR(stall_task)) {
1547                 ret = PTR_ERR(stall_task);
1548                 stall_task = NULL;
1549                 return ret;
1550         }
1551         return 0;
1552 }
1553
1554 /* Clean up after the CPU-stall kthread, if one was spawned. */
1555 static void rcu_torture_stall_cleanup(void)
1556 {
1557         if (stall_task == NULL)
1558                 return;
1559         VERBOSE_PRINTK_STRING("Stopping rcu_torture_stall_task.");
1560         kthread_stop(stall_task);
1561         stall_task = NULL;
1562 }
1563
1564 /* Callback function for RCU barrier testing. */
1565 void rcu_torture_barrier_cbf(struct rcu_head *rcu)
1566 {
1567         atomic_inc(&barrier_cbs_invoked);
1568 }
1569
1570 /* kthread function to register callbacks used to test RCU barriers. */
1571 static int rcu_torture_barrier_cbs(void *arg)
1572 {
1573         long myid = (long)arg;
1574         bool lastphase = 0;
1575         struct rcu_head rcu;
1576
1577         init_rcu_head_on_stack(&rcu);
1578         VERBOSE_PRINTK_STRING("rcu_torture_barrier_cbs task started");
1579         set_user_nice(current, 19);
1580         do {
1581                 wait_event(barrier_cbs_wq[myid],
1582                            barrier_phase != lastphase ||
1583                            kthread_should_stop() ||
1584                            fullstop != FULLSTOP_DONTSTOP);
1585                 lastphase = barrier_phase;
1586                 smp_mb(); /* ensure barrier_phase load before ->call(). */
1587                 if (kthread_should_stop() || fullstop != FULLSTOP_DONTSTOP)
1588                         break;
1589                 cur_ops->call(&rcu, rcu_torture_barrier_cbf);
1590                 if (atomic_dec_and_test(&barrier_cbs_count))
1591                         wake_up(&barrier_wq);
1592         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1593         VERBOSE_PRINTK_STRING("rcu_torture_barrier_cbs task stopping");
1594         rcutorture_shutdown_absorb("rcu_torture_barrier_cbs");
1595         while (!kthread_should_stop())
1596                 schedule_timeout_interruptible(1);
1597         cur_ops->cb_barrier();
1598         destroy_rcu_head_on_stack(&rcu);
1599         return 0;
1600 }
1601
1602 /* kthread function to drive and coordinate RCU barrier testing. */
1603 static int rcu_torture_barrier(void *arg)
1604 {
1605         int i;
1606
1607         VERBOSE_PRINTK_STRING("rcu_torture_barrier task starting");
1608         do {
1609                 atomic_set(&barrier_cbs_invoked, 0);
1610                 atomic_set(&barrier_cbs_count, n_barrier_cbs);
1611                 smp_mb(); /* Ensure barrier_phase after prior assignments. */
1612                 barrier_phase = !barrier_phase;
1613                 for (i = 0; i < n_barrier_cbs; i++)
1614                         wake_up(&barrier_cbs_wq[i]);
1615                 wait_event(barrier_wq,
1616                            atomic_read(&barrier_cbs_count) == 0 ||
1617                            kthread_should_stop() ||
1618                            fullstop != FULLSTOP_DONTSTOP);
1619                 if (kthread_should_stop() || fullstop != FULLSTOP_DONTSTOP)
1620                         break;
1621                 n_barrier_attempts++;
1622                 cur_ops->cb_barrier();
1623                 if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
1624                         n_rcu_torture_barrier_error++;
1625                         WARN_ON_ONCE(1);
1626                 }
1627                 n_barrier_successes++;
1628                 schedule_timeout_interruptible(HZ / 10);
1629         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1630         VERBOSE_PRINTK_STRING("rcu_torture_barrier task stopping");
1631         rcutorture_shutdown_absorb("rcu_torture_barrier");
1632         while (!kthread_should_stop())
1633                 schedule_timeout_interruptible(1);
1634         return 0;
1635 }
1636
1637 /* Initialize RCU barrier testing. */
1638 static int rcu_torture_barrier_init(void)
1639 {
1640         int i;
1641         int ret;
1642
1643         if (n_barrier_cbs == 0)
1644                 return 0;
1645         if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
1646                 pr_alert("%s" TORTURE_FLAG
1647                          " Call or barrier ops missing for %s,\n",
1648                          torture_type, cur_ops->name);
1649                 pr_alert("%s" TORTURE_FLAG
1650                          " RCU barrier testing omitted from run.\n",
1651                          torture_type);
1652                 return 0;
1653         }
1654         atomic_set(&barrier_cbs_count, 0);
1655         atomic_set(&barrier_cbs_invoked, 0);
1656         barrier_cbs_tasks =
1657                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_tasks[0]),
1658                         GFP_KERNEL);
1659         barrier_cbs_wq =
1660                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_wq[0]),
1661                         GFP_KERNEL);
1662         if (barrier_cbs_tasks == NULL || !barrier_cbs_wq)
1663                 return -ENOMEM;
1664         for (i = 0; i < n_barrier_cbs; i++) {
1665                 init_waitqueue_head(&barrier_cbs_wq[i]);
1666                 barrier_cbs_tasks[i] = kthread_run(rcu_torture_barrier_cbs,
1667                                                    (void *)(long)i,
1668                                                    "rcu_torture_barrier_cbs");
1669                 if (IS_ERR(barrier_cbs_tasks[i])) {
1670                         ret = PTR_ERR(barrier_cbs_tasks[i]);
1671                         VERBOSE_PRINTK_ERRSTRING("Failed to create rcu_torture_barrier_cbs");
1672                         barrier_cbs_tasks[i] = NULL;
1673                         return ret;
1674                 }
1675         }
1676         barrier_task = kthread_run(rcu_torture_barrier, NULL,
1677                                    "rcu_torture_barrier");
1678         if (IS_ERR(barrier_task)) {
1679                 ret = PTR_ERR(barrier_task);
1680                 VERBOSE_PRINTK_ERRSTRING("Failed to create rcu_torture_barrier");
1681                 barrier_task = NULL;
1682         }
1683         return 0;
1684 }
1685
1686 /* Clean up after RCU barrier testing. */
1687 static void rcu_torture_barrier_cleanup(void)
1688 {
1689         int i;
1690
1691         if (barrier_task != NULL) {
1692                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_barrier task");
1693                 kthread_stop(barrier_task);
1694                 barrier_task = NULL;
1695         }
1696         if (barrier_cbs_tasks != NULL) {
1697                 for (i = 0; i < n_barrier_cbs; i++) {
1698                         if (barrier_cbs_tasks[i] != NULL) {
1699                                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_barrier_cbs task");
1700                                 kthread_stop(barrier_cbs_tasks[i]);
1701                                 barrier_cbs_tasks[i] = NULL;
1702                         }
1703                 }
1704                 kfree(barrier_cbs_tasks);
1705                 barrier_cbs_tasks = NULL;
1706         }
1707         if (barrier_cbs_wq != NULL) {
1708                 kfree(barrier_cbs_wq);
1709                 barrier_cbs_wq = NULL;
1710         }
1711 }
1712
1713 static int rcutorture_cpu_notify(struct notifier_block *self,
1714                                  unsigned long action, void *hcpu)
1715 {
1716         long cpu = (long)hcpu;
1717
1718         switch (action) {
1719         case CPU_ONLINE:
1720         case CPU_DOWN_FAILED:
1721                 (void)rcutorture_booster_init(cpu);
1722                 break;
1723         case CPU_DOWN_PREPARE:
1724                 rcutorture_booster_cleanup(cpu);
1725                 break;
1726         default:
1727                 break;
1728         }
1729         return NOTIFY_OK;
1730 }
1731
1732 static struct notifier_block rcutorture_cpu_nb = {
1733         .notifier_call = rcutorture_cpu_notify,
1734 };
1735
1736 static void
1737 rcu_torture_cleanup(void)
1738 {
1739         int i;
1740
1741         mutex_lock(&fullstop_mutex);
1742         rcutorture_record_test_transition();
1743         if (fullstop == FULLSTOP_SHUTDOWN) {
1744                 pr_warn(/* but going down anyway, so... */
1745                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
1746                 mutex_unlock(&fullstop_mutex);
1747                 schedule_timeout_uninterruptible(10);
1748                 if (cur_ops->cb_barrier != NULL)
1749                         cur_ops->cb_barrier();
1750                 return;
1751         }
1752         fullstop = FULLSTOP_RMMOD;
1753         mutex_unlock(&fullstop_mutex);
1754         unregister_reboot_notifier(&rcutorture_shutdown_nb);
1755         rcu_torture_barrier_cleanup();
1756         rcu_torture_stall_cleanup();
1757         if (stutter_task) {
1758                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
1759                 kthread_stop(stutter_task);
1760         }
1761         stutter_task = NULL;
1762         if (shuffler_task) {
1763                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
1764                 kthread_stop(shuffler_task);
1765                 free_cpumask_var(shuffle_tmp_mask);
1766         }
1767         shuffler_task = NULL;
1768
1769         if (writer_task) {
1770                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
1771                 kthread_stop(writer_task);
1772         }
1773         writer_task = NULL;
1774
1775         if (reader_tasks) {
1776                 for (i = 0; i < nrealreaders; i++) {
1777                         if (reader_tasks[i]) {
1778                                 VERBOSE_PRINTK_STRING(
1779                                         "Stopping rcu_torture_reader task");
1780                                 kthread_stop(reader_tasks[i]);
1781                         }
1782                         reader_tasks[i] = NULL;
1783                 }
1784                 kfree(reader_tasks);
1785                 reader_tasks = NULL;
1786         }
1787         rcu_torture_current = NULL;
1788
1789         if (fakewriter_tasks) {
1790                 for (i = 0; i < nfakewriters; i++) {
1791                         if (fakewriter_tasks[i]) {
1792                                 VERBOSE_PRINTK_STRING(
1793                                         "Stopping rcu_torture_fakewriter task");
1794                                 kthread_stop(fakewriter_tasks[i]);
1795                         }
1796                         fakewriter_tasks[i] = NULL;
1797                 }
1798                 kfree(fakewriter_tasks);
1799                 fakewriter_tasks = NULL;
1800         }
1801
1802         if (stats_task) {
1803                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
1804                 kthread_stop(stats_task);
1805         }
1806         stats_task = NULL;
1807
1808         if (fqs_task) {
1809                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_fqs task");
1810                 kthread_stop(fqs_task);
1811         }
1812         fqs_task = NULL;
1813         if ((test_boost == 1 && cur_ops->can_boost) ||
1814             test_boost == 2) {
1815                 unregister_cpu_notifier(&rcutorture_cpu_nb);
1816                 for_each_possible_cpu(i)
1817                         rcutorture_booster_cleanup(i);
1818         }
1819         if (shutdown_task != NULL) {
1820                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shutdown task");
1821                 kthread_stop(shutdown_task);
1822         }
1823         shutdown_task = NULL;
1824         rcu_torture_onoff_cleanup();
1825
1826         /* Wait for all RCU callbacks to fire.  */
1827
1828         if (cur_ops->cb_barrier != NULL)
1829                 cur_ops->cb_barrier();
1830
1831         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1832
1833         if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
1834                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1835         else if (n_online_successes != n_online_attempts ||
1836                  n_offline_successes != n_offline_attempts)
1837                 rcu_torture_print_module_parms(cur_ops,
1838                                                "End of test: RCU_HOTPLUG");
1839         else
1840                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1841 }
1842
1843 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1844 static void rcu_torture_leak_cb(struct rcu_head *rhp)
1845 {
1846 }
1847
1848 static void rcu_torture_err_cb(struct rcu_head *rhp)
1849 {
1850         /*
1851          * This -might- happen due to race conditions, but is unlikely.
1852          * The scenario that leads to this happening is that the
1853          * first of the pair of duplicate callbacks is queued,
1854          * someone else starts a grace period that includes that
1855          * callback, then the second of the pair must wait for the
1856          * next grace period.  Unlikely, but can happen.  If it
1857          * does happen, the debug-objects subsystem won't have splatted.
1858          */
1859         pr_alert("rcutorture: duplicated callback was invoked.\n");
1860 }
1861 #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1862
1863 /*
1864  * Verify that double-free causes debug-objects to complain, but only
1865  * if CONFIG_DEBUG_OBJECTS_RCU_HEAD=y.  Otherwise, say that the test
1866  * cannot be carried out.
1867  */
1868 static void rcu_test_debug_objects(void)
1869 {
1870 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1871         struct rcu_head rh1;
1872         struct rcu_head rh2;
1873
1874         init_rcu_head_on_stack(&rh1);
1875         init_rcu_head_on_stack(&rh2);
1876         pr_alert("rcutorture: WARN: Duplicate call_rcu() test starting.\n");
1877
1878         /* Try to queue the rh2 pair of callbacks for the same grace period. */
1879         preempt_disable(); /* Prevent preemption from interrupting test. */
1880         rcu_read_lock(); /* Make it impossible to finish a grace period. */
1881         call_rcu(&rh1, rcu_torture_leak_cb); /* Start grace period. */
1882         local_irq_disable(); /* Make it harder to start a new grace period. */
1883         call_rcu(&rh2, rcu_torture_leak_cb);
1884         call_rcu(&rh2, rcu_torture_err_cb); /* Duplicate callback. */
1885         local_irq_enable();
1886         rcu_read_unlock();
1887         preempt_enable();
1888
1889         /* Wait for them all to get done so we can safely return. */
1890         rcu_barrier();
1891         pr_alert("rcutorture: WARN: Duplicate call_rcu() test complete.\n");
1892         destroy_rcu_head_on_stack(&rh1);
1893         destroy_rcu_head_on_stack(&rh2);
1894 #else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1895         pr_alert("rcutorture: !CONFIG_DEBUG_OBJECTS_RCU_HEAD, not testing duplicate call_rcu()\n");
1896 #endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1897 }
1898
1899 static int __init
1900 rcu_torture_init(void)
1901 {
1902         int i;
1903         int cpu;
1904         int firsterr = 0;
1905         int retval;
1906         static struct rcu_torture_ops *torture_ops[] = {
1907                 &rcu_ops, &rcu_bh_ops, &srcu_ops, &sched_ops,
1908         };
1909
1910         mutex_lock(&fullstop_mutex);
1911
1912         /* Process args and tell the world that the torturer is on the job. */
1913         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1914                 cur_ops = torture_ops[i];
1915                 if (strcmp(torture_type, cur_ops->name) == 0)
1916                         break;
1917         }
1918         if (i == ARRAY_SIZE(torture_ops)) {
1919                 pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
1920                          torture_type);
1921                 pr_alert("rcu-torture types:");
1922                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1923                         pr_alert(" %s", torture_ops[i]->name);
1924                 pr_alert("\n");
1925                 mutex_unlock(&fullstop_mutex);
1926                 return -EINVAL;
1927         }
1928         if (cur_ops->fqs == NULL && fqs_duration != 0) {
1929                 pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
1930                 fqs_duration = 0;
1931         }
1932         if (cur_ops->init)
1933                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1934
1935         if (nreaders >= 0)
1936                 nrealreaders = nreaders;
1937         else
1938                 nrealreaders = 2 * num_online_cpus();
1939         rcu_torture_print_module_parms(cur_ops, "Start of test");
1940         fullstop = FULLSTOP_DONTSTOP;
1941
1942         /* Set up the freelist. */
1943
1944         INIT_LIST_HEAD(&rcu_torture_freelist);
1945         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1946                 rcu_tortures[i].rtort_mbtest = 0;
1947                 list_add_tail(&rcu_tortures[i].rtort_free,
1948                               &rcu_torture_freelist);
1949         }
1950
1951         /* Initialize the statistics so that each run gets its own numbers. */
1952
1953         rcu_torture_current = NULL;
1954         rcu_torture_current_version = 0;
1955         atomic_set(&n_rcu_torture_alloc, 0);
1956         atomic_set(&n_rcu_torture_alloc_fail, 0);
1957         atomic_set(&n_rcu_torture_free, 0);
1958         atomic_set(&n_rcu_torture_mberror, 0);
1959         atomic_set(&n_rcu_torture_error, 0);
1960         n_rcu_torture_barrier_error = 0;
1961         n_rcu_torture_boost_ktrerror = 0;
1962         n_rcu_torture_boost_rterror = 0;
1963         n_rcu_torture_boost_failure = 0;
1964         n_rcu_torture_boosts = 0;
1965         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1966                 atomic_set(&rcu_torture_wcount[i], 0);
1967         for_each_possible_cpu(cpu) {
1968                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1969                         per_cpu(rcu_torture_count, cpu)[i] = 0;
1970                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
1971                 }
1972         }
1973
1974         /* Start up the kthreads. */
1975
1976         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
1977         writer_task = kthread_create(rcu_torture_writer, NULL,
1978                                      "rcu_torture_writer");
1979         if (IS_ERR(writer_task)) {
1980                 firsterr = PTR_ERR(writer_task);
1981                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
1982                 writer_task = NULL;
1983                 goto unwind;
1984         }
1985         wake_up_process(writer_task);
1986         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1987                                    GFP_KERNEL);
1988         if (fakewriter_tasks == NULL) {
1989                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1990                 firsterr = -ENOMEM;
1991                 goto unwind;
1992         }
1993         for (i = 0; i < nfakewriters; i++) {
1994                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
1995                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
1996                                                   "rcu_torture_fakewriter");
1997                 if (IS_ERR(fakewriter_tasks[i])) {
1998                         firsterr = PTR_ERR(fakewriter_tasks[i]);
1999                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
2000                         fakewriter_tasks[i] = NULL;
2001                         goto unwind;
2002                 }
2003         }
2004         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
2005                                GFP_KERNEL);
2006         if (reader_tasks == NULL) {
2007                 VERBOSE_PRINTK_ERRSTRING("out of memory");
2008                 firsterr = -ENOMEM;
2009                 goto unwind;
2010         }
2011         for (i = 0; i < nrealreaders; i++) {
2012                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
2013                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
2014                                               "rcu_torture_reader");
2015                 if (IS_ERR(reader_tasks[i])) {
2016                         firsterr = PTR_ERR(reader_tasks[i]);
2017                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
2018                         reader_tasks[i] = NULL;
2019                         goto unwind;
2020                 }
2021         }
2022         if (stat_interval > 0) {
2023                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
2024                 stats_task = kthread_run(rcu_torture_stats, NULL,
2025                                         "rcu_torture_stats");
2026                 if (IS_ERR(stats_task)) {
2027                         firsterr = PTR_ERR(stats_task);
2028                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
2029                         stats_task = NULL;
2030                         goto unwind;
2031                 }
2032         }
2033         if (test_no_idle_hz) {
2034                 rcu_idle_cpu = num_online_cpus() - 1;
2035
2036                 if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
2037                         firsterr = -ENOMEM;
2038                         VERBOSE_PRINTK_ERRSTRING("Failed to alloc mask");
2039                         goto unwind;
2040                 }
2041
2042                 /* Create the shuffler thread */
2043                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
2044                                           "rcu_torture_shuffle");
2045                 if (IS_ERR(shuffler_task)) {
2046                         free_cpumask_var(shuffle_tmp_mask);
2047                         firsterr = PTR_ERR(shuffler_task);
2048                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
2049                         shuffler_task = NULL;
2050                         goto unwind;
2051                 }
2052         }
2053         if (stutter < 0)
2054                 stutter = 0;
2055         if (stutter) {
2056                 /* Create the stutter thread */
2057                 stutter_task = kthread_run(rcu_torture_stutter, NULL,
2058                                           "rcu_torture_stutter");
2059                 if (IS_ERR(stutter_task)) {
2060                         firsterr = PTR_ERR(stutter_task);
2061                         VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
2062                         stutter_task = NULL;
2063                         goto unwind;
2064                 }
2065         }
2066         if (fqs_duration < 0)
2067                 fqs_duration = 0;
2068         if (fqs_duration) {
2069                 /* Create the stutter thread */
2070                 fqs_task = kthread_run(rcu_torture_fqs, NULL,
2071                                        "rcu_torture_fqs");
2072                 if (IS_ERR(fqs_task)) {
2073                         firsterr = PTR_ERR(fqs_task);
2074                         VERBOSE_PRINTK_ERRSTRING("Failed to create fqs");
2075                         fqs_task = NULL;
2076                         goto unwind;
2077                 }
2078         }
2079         if (test_boost_interval < 1)
2080                 test_boost_interval = 1;
2081         if (test_boost_duration < 2)
2082                 test_boost_duration = 2;
2083         if ((test_boost == 1 && cur_ops->can_boost) ||
2084             test_boost == 2) {
2085
2086                 boost_starttime = jiffies + test_boost_interval * HZ;
2087                 register_cpu_notifier(&rcutorture_cpu_nb);
2088                 for_each_possible_cpu(i) {
2089                         if (cpu_is_offline(i))
2090                                 continue;  /* Heuristic: CPU can go offline. */
2091                         retval = rcutorture_booster_init(i);
2092                         if (retval < 0) {
2093                                 firsterr = retval;
2094                                 goto unwind;
2095                         }
2096                 }
2097         }
2098         if (shutdown_secs > 0) {
2099                 shutdown_time = jiffies + shutdown_secs * HZ;
2100                 shutdown_task = kthread_create(rcu_torture_shutdown, NULL,
2101                                                "rcu_torture_shutdown");
2102                 if (IS_ERR(shutdown_task)) {
2103                         firsterr = PTR_ERR(shutdown_task);
2104                         VERBOSE_PRINTK_ERRSTRING("Failed to create shutdown");
2105                         shutdown_task = NULL;
2106                         goto unwind;
2107                 }
2108                 wake_up_process(shutdown_task);
2109         }
2110         i = rcu_torture_onoff_init();
2111         if (i != 0) {
2112                 firsterr = i;
2113                 goto unwind;
2114         }
2115         register_reboot_notifier(&rcutorture_shutdown_nb);
2116         i = rcu_torture_stall_init();
2117         if (i != 0) {
2118                 firsterr = i;
2119                 goto unwind;
2120         }
2121         retval = rcu_torture_barrier_init();
2122         if (retval != 0) {
2123                 firsterr = retval;
2124                 goto unwind;
2125         }
2126         if (object_debug)
2127                 rcu_test_debug_objects();
2128         rcutorture_record_test_transition();
2129         mutex_unlock(&fullstop_mutex);
2130         return 0;
2131
2132 unwind:
2133         mutex_unlock(&fullstop_mutex);
2134         rcu_torture_cleanup();
2135         return firsterr;
2136 }
2137
2138 module_init(rcu_torture_init);
2139 module_exit(rcu_torture_cleanup);