kernel/rcu/torture.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 MODULE_ALIAS("rcutorture");
  56 #ifdef MODULE_PARAM_PREFIX
  57 #undef MODULE_PARAM_PREFIX
  58 #endif
  59 #define MODULE_PARAM_PREFIX "rcutorture."
  60
  61 static int fqs_duration;
  62 module_param(fqs_duration, int, 0444);
  63 MODULE_PARM_DESC(fqs_duration, "Duration of fqs bursts (us), 0 to disable");
  64 static int fqs_holdoff;
  65 module_param(fqs_holdoff, int, 0444);
  66 MODULE_PARM_DESC(fqs_holdoff, "Holdoff time within fqs bursts (us)");
  67 static int fqs_stutter = 3;
  68 module_param(fqs_stutter, int, 0444);
  69 MODULE_PARM_DESC(fqs_stutter, "Wait time between fqs bursts (s)");
  70 static bool gp_exp;
  71 module_param(gp_exp, bool, 0444);
  72 MODULE_PARM_DESC(gp_exp, "Use expedited GP wait primitives");
  73 static bool gp_normal;
  74 module_param(gp_normal, bool, 0444);
  75 MODULE_PARM_DESC(gp_normal, "Use normal (non-expedited) GP wait primitives");
  76 static int irqreader = 1;
  77 module_param(irqreader, int, 0444);
  78 MODULE_PARM_DESC(irqreader, "Allow RCU readers from irq handlers");
  79 static int n_barrier_cbs;
  80 module_param(n_barrier_cbs, int, 0444);
  81 MODULE_PARM_DESC(n_barrier_cbs, "# of callbacks/kthreads for barrier testing");
  82 static int nfakewriters = 4;
  83 module_param(nfakewriters, int, 0444);
  84 MODULE_PARM_DESC(nfakewriters, "Number of RCU fake writer threads");
  85 static int nreaders = -1;
  86 module_param(nreaders, int, 0444);
  87 MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
  88 static int object_debug;
  89 module_param(object_debug, int, 0444);
  90 MODULE_PARM_DESC(object_debug, "Enable debug-object double call_rcu() testing");
  91 static int onoff_holdoff;
  92 module_param(onoff_holdoff, int, 0444);
  93 MODULE_PARM_DESC(onoff_holdoff, "Time after boot before CPU hotplugs (s)");
  94 static int onoff_interval;
  95 module_param(onoff_interval, int, 0444);
  96 MODULE_PARM_DESC(onoff_interval, "Time between CPU hotplugs (s), 0=disable");
  97 static int shuffle_interval = 3;
  98 module_param(shuffle_interval, int, 0444);
  99 MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
 100 static int shutdown_secs;
 101 module_param(shutdown_secs, int, 0444);
 102 MODULE_PARM_DESC(shutdown_secs, "Shutdown time (s), <= zero to disable.");
 103 static int stall_cpu;
 104 module_param(stall_cpu, int, 0444);
 105 MODULE_PARM_DESC(stall_cpu, "Stall duration (s), zero to disable.");
 106 static int stall_cpu_holdoff = 10;
 107 module_param(stall_cpu_holdoff, int, 0444);
 108 MODULE_PARM_DESC(stall_cpu_holdoff, "Time to wait before starting stall (s).");
 109 static int stat_interval = 60;
 110 module_param(stat_interval, int, 0644);
 111 MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
 112 static int stutter = 5;
 113 module_param(stutter, int, 0444);
 114 MODULE_PARM_DESC(stutter, "Number of seconds to run/halt test");
 115 static int test_boost = 1;
 116 module_param(test_boost, int, 0444);
 117 MODULE_PARM_DESC(test_boost, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
 118 static int test_boost_duration = 4;
 119 module_param(test_boost_duration, int, 0444);
 120 MODULE_PARM_DESC(test_boost_duration, "Duration of each boost test, seconds.");
 121 static int test_boost_interval = 7;
 122 module_param(test_boost_interval, int, 0444);
 123 MODULE_PARM_DESC(test_boost_interval, "Interval between boost tests, seconds.");
 124 static bool test_no_idle_hz = true;
 125 module_param(test_no_idle_hz, bool, 0444);
 126 MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
 127 static char *torture_type = "rcu";
 128 module_param(torture_type, charp, 0444);
 129 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, ...)");
 130 static bool verbose;
 131 module_param(verbose, bool, 0444);
 132 MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
 133
 134 #define TORTURE_FLAG "-torture:"
 135 #define PRINTK_STRING(s) \
 136         do { pr_alert("%s" TORTURE_FLAG s "\n", torture_type); } while (0)
 137 #define VERBOSE_PRINTK_STRING(s) \
 138         do { if (verbose) pr_alert("%s" TORTURE_FLAG s "\n", torture_type); } while (0)
 139 #define VERBOSE_PRINTK_ERRSTRING(s) \
 140         do { if (verbose) pr_alert("%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
 141
 142 static char printk_buf[4096];
 143
 144 static int nrealreaders;
 145 static struct task_struct *writer_task;
 146 static struct task_struct **fakewriter_tasks;
 147 static struct task_struct **reader_tasks;
 148 static struct task_struct *stats_task;
 149 static struct task_struct *shuffler_task;
 150 static struct task_struct *stutter_task;
 151 static struct task_struct *fqs_task;
 152 static struct task_struct *boost_tasks[NR_CPUS];
 153 static struct task_struct *shutdown_task;
 154 #ifdef CONFIG_HOTPLUG_CPU
 155 static struct task_struct *onoff_task;
 156 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
 157 static struct task_struct *stall_task;
 158 static struct task_struct **barrier_cbs_tasks;
 159 static struct task_struct *barrier_task;
 160
 161 #define RCU_TORTURE_PIPE_LEN 10
 162
 163 struct rcu_torture {
 164         struct rcu_head rtort_rcu;
 165         int rtort_pipe_count;
 166         struct list_head rtort_free;
 167         int rtort_mbtest;
 168 };
 169
 170 static LIST_HEAD(rcu_torture_freelist);
 171 static struct rcu_torture __rcu *rcu_torture_current;
 172 static unsigned long rcu_torture_current_version;
 173 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 174 static DEFINE_SPINLOCK(rcu_torture_lock);
 175 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
 176         { 0 };
 177 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) =
 178         { 0 };
 179 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 180 static atomic_t n_rcu_torture_alloc;
 181 static atomic_t n_rcu_torture_alloc_fail;
 182 static atomic_t n_rcu_torture_free;
 183 static atomic_t n_rcu_torture_mberror;
 184 static atomic_t n_rcu_torture_error;
 185 static long n_rcu_torture_barrier_error;
 186 static long n_rcu_torture_boost_ktrerror;
 187 static long n_rcu_torture_boost_rterror;
 188 static long n_rcu_torture_boost_failure;
 189 static long n_rcu_torture_boosts;
 190 static long n_rcu_torture_timers;
 191 static long n_offline_attempts;
 192 static long n_offline_successes;
 193 static unsigned long sum_offline;
 194 static int min_offline = -1;
 195 static int max_offline;
 196 static long n_online_attempts;
 197 static long n_online_successes;
 198 static unsigned long sum_online;
 199 static int min_online = -1;
 200 static int max_online;
 201 static long n_barrier_attempts;
 202 static long n_barrier_successes;
 203 static struct list_head rcu_torture_removed;
 204 static cpumask_var_t shuffle_tmp_mask;
 205
 206 static int stutter_pause_test;
 207
 208 #if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
 209 #define RCUTORTURE_RUNNABLE_INIT 1
 210 #else
 211 #define RCUTORTURE_RUNNABLE_INIT 0
 212 #endif
 213 int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT;
 214 module_param(rcutorture_runnable, int, 0444);
 215 MODULE_PARM_DESC(rcutorture_runnable, "Start rcutorture at boot");
 216
 217 #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
 218 #define rcu_can_boost() 1
 219 #else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 220 #define rcu_can_boost() 0
 221 #endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 222
 223 #ifdef CONFIG_RCU_TRACE
 224 static u64 notrace rcu_trace_clock_local(void)
 225 {
 226         u64 ts = trace_clock_local();
 227         unsigned long __maybe_unused ts_rem = do_div(ts, NSEC_PER_USEC);
 228         return ts;
 229 }
 230 #else /* #ifdef CONFIG_RCU_TRACE */
 231 static u64 notrace rcu_trace_clock_local(void)
 232 {
 233         return 0ULL;
 234 }
 235 #endif /* #else #ifdef CONFIG_RCU_TRACE */
 236
 237 static unsigned long shutdown_time;     /* jiffies to system shutdown. */
 238 static unsigned long boost_starttime;   /* jiffies of next boost test start. */
 239 DEFINE_MUTEX(boost_mutex);              /* protect setting boost_starttime */
 240                                         /*  and boost task create/destroy. */
 241 static atomic_t barrier_cbs_count;      /* Barrier callbacks registered. */
 242 static bool barrier_phase;              /* Test phase. */
 243 static atomic_t barrier_cbs_invoked;    /* Barrier callbacks invoked. */
 244 static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */
 245 static DECLARE_WAIT_QUEUE_HEAD(barrier_wq);
 246
 247 /* Mediate rmmod and system shutdown.  Concurrent rmmod & shutdown illegal! */
 248
 249 #define FULLSTOP_DONTSTOP 0     /* Normal operation. */
 250 #define FULLSTOP_SHUTDOWN 1     /* System shutdown with rcutorture running. */
 251 #define FULLSTOP_RMMOD    2     /* Normal rmmod of rcutorture. */
 252 static int fullstop = FULLSTOP_RMMOD;
 253 /*
 254  * Protect fullstop transitions and spawning of kthreads.
 255  */
 256 static DEFINE_MUTEX(fullstop_mutex);
 257
 258 /* Forward reference. */
 259 static void rcu_torture_cleanup(void);
 260
 261 /*
 262  * Detect and respond to a system shutdown.
 263  */
 264 static int
 265 rcutorture_shutdown_notify(struct notifier_block *unused1,
 266                            unsigned long unused2, void *unused3)
 267 {
 268         mutex_lock(&fullstop_mutex);
 269         if (fullstop == FULLSTOP_DONTSTOP)
 270                 fullstop = FULLSTOP_SHUTDOWN;
 271         else
 272                 pr_warn(/* but going down anyway, so... */
 273                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
 274         mutex_unlock(&fullstop_mutex);
 275         return NOTIFY_DONE;
 276 }
 277
 278 /*
 279  * Absorb kthreads into a kernel function that won't return, so that
 280  * they won't ever access module text or data again.
 281  */
 282 static void rcutorture_shutdown_absorb(const char *title)
 283 {
 284         if (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
 285                 pr_notice(
 286                        "rcutorture thread %s parking due to system shutdown\n",
 287                        title);
 288                 schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
 289         }
 290 }
 291
 292 /*
 293  * Allocate an element from the rcu_tortures pool.
 294  */
 295 static struct rcu_torture *
 296 rcu_torture_alloc(void)
 297 {
 298         struct list_head *p;
 299
 300         spin_lock_bh(&rcu_torture_lock);
 301         if (list_empty(&rcu_torture_freelist)) {
 302                 atomic_inc(&n_rcu_torture_alloc_fail);
 303                 spin_unlock_bh(&rcu_torture_lock);
 304                 return NULL;
 305         }
 306         atomic_inc(&n_rcu_torture_alloc);
 307         p = rcu_torture_freelist.next;
 308         list_del_init(p);
 309         spin_unlock_bh(&rcu_torture_lock);
 310         return container_of(p, struct rcu_torture, rtort_free);
 311 }
 312
 313 /*
 314  * Free an element to the rcu_tortures pool.
 315  */
 316 static void
 317 rcu_torture_free(struct rcu_torture *p)
 318 {
 319         atomic_inc(&n_rcu_torture_free);
 320         spin_lock_bh(&rcu_torture_lock);
 321         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 322         spin_unlock_bh(&rcu_torture_lock);
 323 }
 324
 325 struct rcu_random_state {
 326         unsigned long rrs_state;
 327         long rrs_count;
 328 };
 329
 330 #define RCU_RANDOM_MULT 39916801  /* prime */
 331 #define RCU_RANDOM_ADD  479001701 /* prime */
 332 #define RCU_RANDOM_REFRESH 10000
 333
 334 #define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
 335
 336 /*
 337  * Crude but fast random-number generator.  Uses a linear congruential
 338  * generator, with occasional help from cpu_clock().
 339  */
 340 static unsigned long
 341 rcu_random(struct rcu_random_state *rrsp)
 342 {
 343         if (--rrsp->rrs_count < 0) {
 344                 rrsp->rrs_state += (unsigned long)local_clock();
 345                 rrsp->rrs_count = RCU_RANDOM_REFRESH;
 346         }
 347         rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
 348         return swahw32(rrsp->rrs_state);
 349 }
 350
 351 static void
 352 rcu_stutter_wait(const char *title)
 353 {
 354         while (stutter_pause_test || !rcutorture_runnable) {
 355                 if (rcutorture_runnable)
 356                         schedule_timeout_interruptible(1);
 357                 else
 358                         schedule_timeout_interruptible(round_jiffies_relative(HZ));
 359                 rcutorture_shutdown_absorb(title);
 360         }
 361 }
 362
 363 /*
 364  * Operations vector for selecting different types of tests.
 365  */
 366
 367 struct rcu_torture_ops {
 368         void (*init)(void);
 369         int (*readlock)(void);
 370         void (*read_delay)(struct rcu_random_state *rrsp);
 371         void (*readunlock)(int idx);
 372         int (*completed)(void);
 373         void (*deferred_free)(struct rcu_torture *p);
 374         void (*sync)(void);
 375         void (*exp_sync)(void);
 376         void (*call)(struct rcu_head *head, void (*func)(struct rcu_head *rcu));
 377         void (*cb_barrier)(void);
 378         void (*fqs)(void);
 379         int (*stats)(char *page);
 380         int irq_capable;
 381         int can_boost;
 382         const char *name;
 383 };
 384
 385 static struct rcu_torture_ops *cur_ops;
 386
 387 /*
 388  * Definitions for rcu torture testing.
 389  */
 390
 391 static int rcu_torture_read_lock(void) __acquires(RCU)
 392 {
 393         rcu_read_lock();
 394         return 0;
 395 }
 396
 397 static void rcu_read_delay(struct rcu_random_state *rrsp)
 398 {
 399         const unsigned long shortdelay_us = 200;
 400         const unsigned long longdelay_ms = 50;
 401
 402         /* We want a short delay sometimes to make a reader delay the grace
 403          * period, and we want a long delay occasionally to trigger
 404          * force_quiescent_state. */
 405
 406         if (!(rcu_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
 407                 mdelay(longdelay_ms);
 408         if (!(rcu_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
 409                 udelay(shortdelay_us);
 410 #ifdef CONFIG_PREEMPT
 411         if (!preempt_count() && !(rcu_random(rrsp) % (nrealreaders * 20000)))
 412                 preempt_schedule();  /* No QS if preempt_disable() in effect */
 413 #endif
 414 }
 415
 416 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 417 {
 418         rcu_read_unlock();
 419 }
 420
 421 static int rcu_torture_completed(void)
 422 {
 423         return rcu_batches_completed();
 424 }
 425
 426 static void
 427 rcu_torture_cb(struct rcu_head *p)
 428 {
 429         int i;
 430         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 431
 432         if (fullstop != FULLSTOP_DONTSTOP) {
 433                 /* Test is ending, just drop callbacks on the floor. */
 434                 /* The next initialization will pick up the pieces. */
 435                 return;
 436         }
 437         i = rp->rtort_pipe_count;
 438         if (i > RCU_TORTURE_PIPE_LEN)
 439                 i = RCU_TORTURE_PIPE_LEN;
 440         atomic_inc(&rcu_torture_wcount[i]);
 441         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 442                 rp->rtort_mbtest = 0;
 443                 rcu_torture_free(rp);
 444         } else {
 445                 cur_ops->deferred_free(rp);
 446         }
 447 }
 448
 449 static int rcu_no_completed(void)
 450 {
 451         return 0;
 452 }
 453
 454 static void rcu_torture_deferred_free(struct rcu_torture *p)
 455 {
 456         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 457 }
 458
 459 static void rcu_sync_torture_init(void)
 460 {
 461         INIT_LIST_HEAD(&rcu_torture_removed);
 462 }
 463
 464 static struct rcu_torture_ops rcu_ops = {
 465         .init           = rcu_sync_torture_init,
 466         .readlock       = rcu_torture_read_lock,
 467         .read_delay     = rcu_read_delay,
 468         .readunlock     = rcu_torture_read_unlock,
 469         .completed      = rcu_torture_completed,
 470         .deferred_free  = rcu_torture_deferred_free,
 471         .sync           = synchronize_rcu,
 472         .exp_sync       = synchronize_rcu_expedited,
 473         .call           = call_rcu,
 474         .cb_barrier     = rcu_barrier,
 475         .fqs            = rcu_force_quiescent_state,
 476         .stats          = NULL,
 477         .irq_capable    = 1,
 478         .can_boost      = rcu_can_boost(),
 479         .name           = "rcu"
 480 };
 481
 482 /*
 483  * Definitions for rcu_bh torture testing.
 484  */
 485
 486 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
 487 {
 488         rcu_read_lock_bh();
 489         return 0;
 490 }
 491
 492 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
 493 {
 494         rcu_read_unlock_bh();
 495 }
 496
 497 static int rcu_bh_torture_completed(void)
 498 {
 499         return rcu_batches_completed_bh();
 500 }
 501
 502 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 503 {
 504         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
 505 }
 506
 507 static struct rcu_torture_ops rcu_bh_ops = {
 508         .init           = rcu_sync_torture_init,
 509         .readlock       = rcu_bh_torture_read_lock,
 510         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 511         .readunlock     = rcu_bh_torture_read_unlock,
 512         .completed      = rcu_bh_torture_completed,
 513         .deferred_free  = rcu_bh_torture_deferred_free,
 514         .sync           = synchronize_rcu_bh,
 515         .exp_sync       = synchronize_rcu_bh_expedited,
 516         .call           = call_rcu_bh,
 517         .cb_barrier     = rcu_barrier_bh,
 518         .fqs            = rcu_bh_force_quiescent_state,
 519         .stats          = NULL,
 520         .irq_capable    = 1,
 521         .name           = "rcu_bh"
 522 };
 523
 524 /*
 525  * Definitions for srcu torture testing.
 526  */
 527
 528 DEFINE_STATIC_SRCU(srcu_ctl);
 529
 530 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
 531 {
 532         return srcu_read_lock(&srcu_ctl);
 533 }
 534
 535 static void srcu_read_delay(struct rcu_random_state *rrsp)
 536 {
 537         long delay;
 538         const long uspertick = 1000000 / HZ;
 539         const long longdelay = 10;
 540
 541         /* We want there to be long-running readers, but not all the time. */
 542
 543         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
 544         if (!delay)
 545                 schedule_timeout_interruptible(longdelay);
 546         else
 547                 rcu_read_delay(rrsp);
 548 }
 549
 550 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
 551 {
 552         srcu_read_unlock(&srcu_ctl, idx);
 553 }
 554
 555 static int srcu_torture_completed(void)
 556 {
 557         return srcu_batches_completed(&srcu_ctl);
 558 }
 559
 560 static void srcu_torture_deferred_free(struct rcu_torture *rp)
 561 {
 562         call_srcu(&srcu_ctl, &rp->rtort_rcu, rcu_torture_cb);
 563 }
 564
 565 static void srcu_torture_synchronize(void)
 566 {
 567         synchronize_srcu(&srcu_ctl);
 568 }
 569
 570 static void srcu_torture_call(struct rcu_head *head,
 571                               void (*func)(struct rcu_head *head))
 572 {
 573         call_srcu(&srcu_ctl, head, func);
 574 }
 575
 576 static void srcu_torture_barrier(void)
 577 {
 578         srcu_barrier(&srcu_ctl);
 579 }
 580
 581 static int srcu_torture_stats(char *page)
 582 {
 583         int cnt = 0;
 584         int cpu;
 585         int idx = srcu_ctl.completed & 0x1;
 586
 587         cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
 588                        torture_type, TORTURE_FLAG, idx);
 589         for_each_possible_cpu(cpu) {
 590                 cnt += sprintf(&page[cnt], " %d(%lu,%lu)", cpu,
 591                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
 592                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
 593         }
 594         cnt += sprintf(&page[cnt], "\n");
 595         return cnt;
 596 }
 597
 598 static void srcu_torture_synchronize_expedited(void)
 599 {
 600         synchronize_srcu_expedited(&srcu_ctl);
 601 }
 602
 603 static struct rcu_torture_ops srcu_ops = {
 604         .init           = rcu_sync_torture_init,
 605         .readlock       = srcu_torture_read_lock,
 606         .read_delay     = srcu_read_delay,
 607         .readunlock     = srcu_torture_read_unlock,
 608         .completed      = srcu_torture_completed,
 609         .deferred_free  = srcu_torture_deferred_free,
 610         .sync           = srcu_torture_synchronize,
 611         .exp_sync       = srcu_torture_synchronize_expedited,
 612         .call           = srcu_torture_call,
 613         .cb_barrier     = srcu_torture_barrier,
 614         .stats          = srcu_torture_stats,
 615         .name           = "srcu"
 616 };
 617
 618 /*
 619  * Definitions for sched torture testing.
 620  */
 621
 622 static int sched_torture_read_lock(void)
 623 {
 624         preempt_disable();
 625         return 0;
 626 }
 627
 628 static void sched_torture_read_unlock(int idx)
 629 {
 630         preempt_enable();
 631 }
 632
 633 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
 634 {
 635         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
 636 }
 637
 638 static struct rcu_torture_ops sched_ops = {
 639         .init           = rcu_sync_torture_init,
 640         .readlock       = sched_torture_read_lock,
 641         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 642         .readunlock     = sched_torture_read_unlock,
 643         .completed      = rcu_no_completed,
 644         .deferred_free  = rcu_sched_torture_deferred_free,
 645         .sync           = synchronize_sched,
 646         .exp_sync       = synchronize_sched_expedited,
 647         .call           = call_rcu_sched,
 648         .cb_barrier     = rcu_barrier_sched,
 649         .fqs            = rcu_sched_force_quiescent_state,
 650         .stats          = NULL,
 651         .irq_capable    = 1,
 652         .name           = "sched"
 653 };
 654
 655 /*
 656  * RCU torture priority-boost testing.  Runs one real-time thread per
 657  * CPU for moderate bursts, repeatedly registering RCU callbacks and
 658  * spinning waiting for them to be invoked.  If a given callback takes
 659  * too long to be invoked, we assume that priority inversion has occurred.
 660  */
 661
 662 struct rcu_boost_inflight {
 663         struct rcu_head rcu;
 664         int inflight;
 665 };
 666
 667 static void rcu_torture_boost_cb(struct rcu_head *head)
 668 {
 669         struct rcu_boost_inflight *rbip =
 670                 container_of(head, struct rcu_boost_inflight, rcu);
 671
 672         smp_mb(); /* Ensure RCU-core accesses precede clearing ->inflight */
 673         rbip->inflight = 0;
 674 }
 675
 676 static int rcu_torture_boost(void *arg)
 677 {
 678         unsigned long call_rcu_time;
 679         unsigned long endtime;
 680         unsigned long oldstarttime;
 681         struct rcu_boost_inflight rbi = { .inflight = 0 };
 682         struct sched_param sp;
 683
 684         VERBOSE_PRINTK_STRING("rcu_torture_boost started");
 685
 686         /* Set real-time priority. */
 687         sp.sched_priority = 1;
 688         if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 689                 VERBOSE_PRINTK_STRING("rcu_torture_boost RT prio failed!");
 690                 n_rcu_torture_boost_rterror++;
 691         }
 692
 693         init_rcu_head_on_stack(&rbi.rcu);
 694         /* Each pass through the following loop does one boost-test cycle. */
 695         do {
 696                 /* Wait for the next test interval. */
 697                 oldstarttime = boost_starttime;
 698                 while (ULONG_CMP_LT(jiffies, oldstarttime)) {
 699                         schedule_timeout_interruptible(oldstarttime - jiffies);
 700                         rcu_stutter_wait("rcu_torture_boost");
 701                         if (kthread_should_stop() ||
 702                             fullstop != FULLSTOP_DONTSTOP)
 703                                 goto checkwait;
 704                 }
 705
 706                 /* Do one boost-test interval. */
 707                 endtime = oldstarttime + test_boost_duration * HZ;
 708                 call_rcu_time = jiffies;
 709                 while (ULONG_CMP_LT(jiffies, endtime)) {
 710                         /* If we don't have a callback in flight, post one. */
 711                         if (!rbi.inflight) {
 712                                 smp_mb(); /* RCU core before ->inflight = 1. */
 713                                 rbi.inflight = 1;
 714                                 call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 715                                 if (jiffies - call_rcu_time >
 716                                          test_boost_duration * HZ - HZ / 2) {
 717                                         VERBOSE_PRINTK_STRING("rcu_torture_boost boosting failed");
 718                                         n_rcu_torture_boost_failure++;
 719                                 }
 720                                 call_rcu_time = jiffies;
 721                         }
 722                         cond_resched();
 723                         rcu_stutter_wait("rcu_torture_boost");
 724                         if (kthread_should_stop() ||
 725                             fullstop != FULLSTOP_DONTSTOP)
 726                                 goto checkwait;
 727                 }
 728
 729                 /*
 730                  * Set the start time of the next test interval.
 731                  * Yes, this is vulnerable to long delays, but such
 732                  * delays simply cause a false negative for the next
 733                  * interval.  Besides, we are running at RT priority,
 734                  * so delays should be relatively rare.
 735                  */
 736                 while (oldstarttime == boost_starttime &&
 737                        !kthread_should_stop()) {
 738                         if (mutex_trylock(&boost_mutex)) {
 739                                 boost_starttime = jiffies +
 740                                                   test_boost_interval * HZ;
 741                                 n_rcu_torture_boosts++;
 742                                 mutex_unlock(&boost_mutex);
 743                                 break;
 744                         }
 745                         schedule_timeout_uninterruptible(1);
 746                 }
 747
 748                 /* Go do the stutter. */
 749 checkwait:      rcu_stutter_wait("rcu_torture_boost");
 750         } while (!kthread_should_stop() && fullstop  == FULLSTOP_DONTSTOP);
 751
 752         /* Clean up and exit. */
 753         VERBOSE_PRINTK_STRING("rcu_torture_boost task stopping");
 754         rcutorture_shutdown_absorb("rcu_torture_boost");
 755         while (!kthread_should_stop() || rbi.inflight)
 756                 schedule_timeout_uninterruptible(1);
 757         smp_mb(); /* order accesses to ->inflight before stack-frame death. */
 758         destroy_rcu_head_on_stack(&rbi.rcu);
 759         return 0;
 760 }
 761
 762 /*
 763  * RCU torture force-quiescent-state kthread.  Repeatedly induces
 764  * bursts of calls to force_quiescent_state(), increasing the probability
 765  * of occurrence of some important types of race conditions.
 766  */
 767 static int
 768 rcu_torture_fqs(void *arg)
 769 {
 770         unsigned long fqs_resume_time;
 771         int fqs_burst_remaining;
 772
 773         VERBOSE_PRINTK_STRING("rcu_torture_fqs task started");
 774         do {
 775                 fqs_resume_time = jiffies + fqs_stutter * HZ;
 776                 while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
 777                        !kthread_should_stop()) {
 778                         schedule_timeout_interruptible(1);
 779                 }
 780                 fqs_burst_remaining = fqs_duration;
 781                 while (fqs_burst_remaining > 0 &&
 782                        !kthread_should_stop()) {
 783                         cur_ops->fqs();
 784                         udelay(fqs_holdoff);
 785                         fqs_burst_remaining -= fqs_holdoff;
 786                 }
 787                 rcu_stutter_wait("rcu_torture_fqs");
 788         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 789         VERBOSE_PRINTK_STRING("rcu_torture_fqs task stopping");
 790         rcutorture_shutdown_absorb("rcu_torture_fqs");
 791         while (!kthread_should_stop())
 792                 schedule_timeout_uninterruptible(1);
 793         return 0;
 794 }
 795
 796 /*
 797  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 798  * for that pointed to by rcu_torture_current, freeing the old structure
 799  * after a series of grace periods (the "pipeline").
 800  */
 801 static int
 802 rcu_torture_writer(void *arg)
 803 {
 804         bool exp;
 805         int i;
 806         struct rcu_torture *rp;
 807         struct rcu_torture *rp1;
 808         struct rcu_torture *old_rp;
 809         static DEFINE_RCU_RANDOM(rand);
 810
 811         VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
 812         set_user_nice(current, 19);
 813
 814         do {
 815                 schedule_timeout_uninterruptible(1);
 816                 rp = rcu_torture_alloc();
 817                 if (rp == NULL)
 818                         continue;
 819                 rp->rtort_pipe_count = 0;
 820                 udelay(rcu_random(&rand) & 0x3ff);
 821                 old_rp = rcu_dereference_check(rcu_torture_current,
 822                                                current == writer_task);
 823                 rp->rtort_mbtest = 1;
 824                 rcu_assign_pointer(rcu_torture_current, rp);
 825                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
 826                 if (old_rp) {
 827                         i = old_rp->rtort_pipe_count;
 828                         if (i > RCU_TORTURE_PIPE_LEN)
 829                                 i = RCU_TORTURE_PIPE_LEN;
 830                         atomic_inc(&rcu_torture_wcount[i]);
 831                         old_rp->rtort_pipe_count++;
 832                         if (gp_normal == gp_exp)
 833                                 exp = !!(rcu_random(&rand) & 0x80);
 834                         else
 835                                 exp = gp_exp;
 836                         if (!exp) {
 837                                 cur_ops->deferred_free(old_rp);
 838                         } else {
 839                                 cur_ops->exp_sync();
 840                                 list_add(&old_rp->rtort_free,
 841                                          &rcu_torture_removed);
 842                                 list_for_each_entry_safe(rp, rp1,
 843                                                          &rcu_torture_removed,
 844                                                          rtort_free) {
 845                                         i = rp->rtort_pipe_count;
 846                                         if (i > RCU_TORTURE_PIPE_LEN)
 847                                                 i = RCU_TORTURE_PIPE_LEN;
 848                                         atomic_inc(&rcu_torture_wcount[i]);
 849                                         if (++rp->rtort_pipe_count >=
 850                                             RCU_TORTURE_PIPE_LEN) {
 851                                                 rp->rtort_mbtest = 0;
 852                                                 list_del(&rp->rtort_free);
 853                                                 rcu_torture_free(rp);
 854                                         }
 855                                  }
 856                         }
 857                 }
 858                 rcutorture_record_progress(++rcu_torture_current_version);
 859                 rcu_stutter_wait("rcu_torture_writer");
 860         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 861         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
 862         rcutorture_shutdown_absorb("rcu_torture_writer");
 863         while (!kthread_should_stop())
 864                 schedule_timeout_uninterruptible(1);
 865         return 0;
 866 }
 867
 868 /*
 869  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
 870  * delay between calls.
 871  */
 872 static int
 873 rcu_torture_fakewriter(void *arg)
 874 {
 875         DEFINE_RCU_RANDOM(rand);
 876
 877         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
 878         set_user_nice(current, 19);
 879
 880         do {
 881                 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
 882                 udelay(rcu_random(&rand) & 0x3ff);
 883                 if (cur_ops->cb_barrier != NULL &&
 884                     rcu_random(&rand) % (nfakewriters * 8) == 0) {
 885                         cur_ops->cb_barrier();
 886                 } else if (gp_normal == gp_exp) {
 887                         if (rcu_random(&rand) & 0x80)
 888                                 cur_ops->sync();
 889                         else
 890                                 cur_ops->exp_sync();
 891                 } else if (gp_normal) {
 892                         cur_ops->sync();
 893                 } else {
 894                         cur_ops->exp_sync();
 895                 }
 896                 rcu_stutter_wait("rcu_torture_fakewriter");
 897         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 898
 899         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
 900         rcutorture_shutdown_absorb("rcu_torture_fakewriter");
 901         while (!kthread_should_stop())
 902                 schedule_timeout_uninterruptible(1);
 903         return 0;
 904 }
 905
 906 void rcutorture_trace_dump(void)
 907 {
 908         static atomic_t beenhere = ATOMIC_INIT(0);
 909
 910         if (atomic_read(&beenhere))
 911                 return;
 912         if (atomic_xchg(&beenhere, 1) != 0)
 913                 return;
 914         ftrace_dump(DUMP_ALL);
 915 }
 916
 917 /*
 918  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
 919  * incrementing the corresponding element of the pipeline array.  The
 920  * counter in the element should never be greater than 1, otherwise, the
 921  * RCU implementation is broken.
 922  */
 923 static void rcu_torture_timer(unsigned long unused)
 924 {
 925         int idx;
 926         int completed;
 927         int completed_end;
 928         static DEFINE_RCU_RANDOM(rand);
 929         static DEFINE_SPINLOCK(rand_lock);
 930         struct rcu_torture *p;
 931         int pipe_count;
 932         unsigned long long ts;
 933
 934         idx = cur_ops->readlock();
 935         completed = cur_ops->completed();
 936         ts = rcu_trace_clock_local();
 937         p = rcu_dereference_check(rcu_torture_current,
 938                                   rcu_read_lock_bh_held() ||
 939                                   rcu_read_lock_sched_held() ||
 940                                   srcu_read_lock_held(&srcu_ctl));
 941         if (p == NULL) {
 942                 /* Leave because rcu_torture_writer is not yet underway */
 943                 cur_ops->readunlock(idx);
 944                 return;
 945         }
 946         if (p->rtort_mbtest == 0)
 947                 atomic_inc(&n_rcu_torture_mberror);
 948         spin_lock(&rand_lock);
 949         cur_ops->read_delay(&rand);
 950         n_rcu_torture_timers++;
 951         spin_unlock(&rand_lock);
 952         preempt_disable();
 953         pipe_count = p->rtort_pipe_count;
 954         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
 955                 /* Should not happen, but... */
 956                 pipe_count = RCU_TORTURE_PIPE_LEN;
 957         }
 958         completed_end = cur_ops->completed();
 959         if (pipe_count > 1) {
 960                 do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu, ts,
 961                                           completed, completed_end);
 962                 rcutorture_trace_dump();
 963         }
 964         __this_cpu_inc(rcu_torture_count[pipe_count]);
 965         completed = completed_end - completed;
 966         if (completed > RCU_TORTURE_PIPE_LEN) {
 967                 /* Should not happen, but... */
 968                 completed = RCU_TORTURE_PIPE_LEN;
 969         }
 970         __this_cpu_inc(rcu_torture_batch[completed]);
 971         preempt_enable();
 972         cur_ops->readunlock(idx);
 973 }
 974
 975 /*
 976  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
 977  * incrementing the corresponding element of the pipeline array.  The
 978  * counter in the element should never be greater than 1, otherwise, the
 979  * RCU implementation is broken.
 980  */
 981 static int
 982 rcu_torture_reader(void *arg)
 983 {
 984         int completed;
 985         int completed_end;
 986         int idx;
 987         DEFINE_RCU_RANDOM(rand);
 988         struct rcu_torture *p;
 989         int pipe_count;
 990         struct timer_list t;
 991         unsigned long long ts;
 992
 993         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
 994         set_user_nice(current, 19);
 995         if (irqreader && cur_ops->irq_capable)
 996                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
 997
 998         do {
 999                 if (irqreader && cur_ops->irq_capable) {
1000                         if (!timer_pending(&t))
1001                                 mod_timer(&t, jiffies + 1);
1002                 }
1003                 idx = cur_ops->readlock();
1004                 completed = cur_ops->completed();
1005                 ts = rcu_trace_clock_local();
1006                 p = rcu_dereference_check(rcu_torture_current,
1007                                           rcu_read_lock_bh_held() ||
1008                                           rcu_read_lock_sched_held() ||
1009                                           srcu_read_lock_held(&srcu_ctl));
1010                 if (p == NULL) {
1011                         /* Wait for rcu_torture_writer to get underway */
1012                         cur_ops->readunlock(idx);
1013                         schedule_timeout_interruptible(HZ);
1014                         continue;
1015                 }
1016                 if (p->rtort_mbtest == 0)
1017                         atomic_inc(&n_rcu_torture_mberror);
1018                 cur_ops->read_delay(&rand);
1019                 preempt_disable();
1020                 pipe_count = p->rtort_pipe_count;
1021                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1022                         /* Should not happen, but... */
1023                         pipe_count = RCU_TORTURE_PIPE_LEN;
1024                 }
1025                 completed_end = cur_ops->completed();
1026                 if (pipe_count > 1) {
1027                         do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
1028                                                   ts, completed, completed_end);
1029                         rcutorture_trace_dump();
1030                 }
1031                 __this_cpu_inc(rcu_torture_count[pipe_count]);
1032                 completed = completed_end - completed;
1033                 if (completed > RCU_TORTURE_PIPE_LEN) {
1034                         /* Should not happen, but... */
1035                         completed = RCU_TORTURE_PIPE_LEN;
1036                 }
1037                 __this_cpu_inc(rcu_torture_batch[completed]);
1038                 preempt_enable();
1039                 cur_ops->readunlock(idx);
1040                 schedule();
1041                 rcu_stutter_wait("rcu_torture_reader");
1042         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1043         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
1044         rcutorture_shutdown_absorb("rcu_torture_reader");
1045         if (irqreader && cur_ops->irq_capable)
1046                 del_timer_sync(&t);
1047         while (!kthread_should_stop())
1048                 schedule_timeout_uninterruptible(1);
1049         return 0;
1050 }
1051
1052 /*
1053  * Create an RCU-torture statistics message in the specified buffer.
1054  */
1055 static int
1056 rcu_torture_printk(char *page)
1057 {
1058         int cnt = 0;
1059         int cpu;
1060         int i;
1061         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1062         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1063
1064         for_each_possible_cpu(cpu) {
1065                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1066                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1067                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1068                 }
1069         }
1070         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1071                 if (pipesummary[i] != 0)
1072                         break;
1073         }
1074         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
1075         cnt += sprintf(&page[cnt],
1076                        "rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
1077                        rcu_torture_current,
1078                        rcu_torture_current_version,
1079                        list_empty(&rcu_torture_freelist),
1080                        atomic_read(&n_rcu_torture_alloc),
1081                        atomic_read(&n_rcu_torture_alloc_fail),
1082                        atomic_read(&n_rcu_torture_free));
1083         cnt += sprintf(&page[cnt], "rtmbe: %d rtbke: %ld rtbre: %ld ",
1084                        atomic_read(&n_rcu_torture_mberror),
1085                        n_rcu_torture_boost_ktrerror,
1086                        n_rcu_torture_boost_rterror);
1087         cnt += sprintf(&page[cnt], "rtbf: %ld rtb: %ld nt: %ld ",
1088                        n_rcu_torture_boost_failure,
1089                        n_rcu_torture_boosts,
1090                        n_rcu_torture_timers);
1091         cnt += sprintf(&page[cnt],
1092                        "onoff: %ld/%ld:%ld/%ld %d,%d:%d,%d %lu:%lu (HZ=%d) ",
1093                        n_online_successes, n_online_attempts,
1094                        n_offline_successes, n_offline_attempts,
1095                        min_online, max_online,
1096                        min_offline, max_offline,
1097                        sum_online, sum_offline, HZ);
1098         cnt += sprintf(&page[cnt], "barrier: %ld/%ld:%ld",
1099                        n_barrier_successes,
1100                        n_barrier_attempts,
1101                        n_rcu_torture_barrier_error);
1102         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1103         if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1104             n_rcu_torture_barrier_error != 0 ||
1105             n_rcu_torture_boost_ktrerror != 0 ||
1106             n_rcu_torture_boost_rterror != 0 ||
1107             n_rcu_torture_boost_failure != 0 ||
1108             i > 1) {
1109                 cnt += sprintf(&page[cnt], "!!! ");
1110                 atomic_inc(&n_rcu_torture_error);
1111                 WARN_ON_ONCE(1);
1112         }
1113         cnt += sprintf(&page[cnt], "Reader Pipe: ");
1114         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1115                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
1116         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1117         cnt += sprintf(&page[cnt], "Reader Batch: ");
1118         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1119                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
1120         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1121         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
1122         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1123                 cnt += sprintf(&page[cnt], " %d",
1124                                atomic_read(&rcu_torture_wcount[i]));
1125         }
1126         cnt += sprintf(&page[cnt], "\n");
1127         if (cur_ops->stats)
1128                 cnt += cur_ops->stats(&page[cnt]);
1129         return cnt;
1130 }
1131
1132 /*
1133  * Print torture statistics.  Caller must ensure that there is only
1134  * one call to this function at a given time!!!  This is normally
1135  * accomplished by relying on the module system to only have one copy
1136  * of the module loaded, and then by giving the rcu_torture_stats
1137  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1138  * thread is not running).
1139  */
1140 static void
1141 rcu_torture_stats_print(void)
1142 {
1143         int cnt;
1144
1145         cnt = rcu_torture_printk(printk_buf);
1146         pr_alert("%s", printk_buf);
1147 }
1148
1149 /*
1150  * Periodically prints torture statistics, if periodic statistics printing
1151  * was specified via the stat_interval module parameter.
1152  *
1153  * No need to worry about fullstop here, since this one doesn't reference
1154  * volatile state or register callbacks.
1155  */
1156 static int
1157 rcu_torture_stats(void *arg)
1158 {
1159         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
1160         do {
1161                 schedule_timeout_interruptible(stat_interval * HZ);
1162                 rcu_torture_stats_print();
1163                 rcutorture_shutdown_absorb("rcu_torture_stats");
1164         } while (!kthread_should_stop());
1165         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
1166         return 0;
1167 }
1168
1169 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
1170
1171 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
1172  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
1173  */
1174 static void rcu_torture_shuffle_tasks(void)
1175 {
1176         int i;
1177
1178         cpumask_setall(shuffle_tmp_mask);
1179         get_online_cpus();
1180
1181         /* No point in shuffling if there is only one online CPU (ex: UP) */
1182         if (num_online_cpus() == 1) {
1183                 put_online_cpus();
1184                 return;
1185         }
1186
1187         if (rcu_idle_cpu != -1)
1188                 cpumask_clear_cpu(rcu_idle_cpu, shuffle_tmp_mask);
1189
1190         set_cpus_allowed_ptr(current, shuffle_tmp_mask);
1191
1192         if (reader_tasks) {
1193                 for (i = 0; i < nrealreaders; i++)
1194                         if (reader_tasks[i])
1195                                 set_cpus_allowed_ptr(reader_tasks[i],
1196                                                      shuffle_tmp_mask);
1197         }
1198         if (fakewriter_tasks) {
1199                 for (i = 0; i < nfakewriters; i++)
1200                         if (fakewriter_tasks[i])
1201                                 set_cpus_allowed_ptr(fakewriter_tasks[i],
1202                                                      shuffle_tmp_mask);
1203         }
1204         if (writer_task)
1205                 set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
1206         if (stats_task)
1207                 set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
1208         if (stutter_task)
1209                 set_cpus_allowed_ptr(stutter_task, shuffle_tmp_mask);
1210         if (fqs_task)
1211                 set_cpus_allowed_ptr(fqs_task, shuffle_tmp_mask);
1212         if (shutdown_task)
1213                 set_cpus_allowed_ptr(shutdown_task, shuffle_tmp_mask);
1214 #ifdef CONFIG_HOTPLUG_CPU
1215         if (onoff_task)
1216                 set_cpus_allowed_ptr(onoff_task, shuffle_tmp_mask);
1217 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
1218         if (stall_task)
1219                 set_cpus_allowed_ptr(stall_task, shuffle_tmp_mask);
1220         if (barrier_cbs_tasks)
1221                 for (i = 0; i < n_barrier_cbs; i++)
1222                         if (barrier_cbs_tasks[i])
1223                                 set_cpus_allowed_ptr(barrier_cbs_tasks[i],
1224                                                      shuffle_tmp_mask);
1225         if (barrier_task)
1226                 set_cpus_allowed_ptr(barrier_task, shuffle_tmp_mask);
1227
1228         if (rcu_idle_cpu == -1)
1229                 rcu_idle_cpu = num_online_cpus() - 1;
1230         else
1231                 rcu_idle_cpu--;
1232
1233         put_online_cpus();
1234 }
1235
1236 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
1237  * system to become idle at a time and cut off its timer ticks. This is meant
1238  * to test the support for such tickless idle CPU in RCU.
1239  */
1240 static int
1241 rcu_torture_shuffle(void *arg)
1242 {
1243         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
1244         do {
1245                 schedule_timeout_interruptible(shuffle_interval * HZ);
1246                 rcu_torture_shuffle_tasks();
1247                 rcutorture_shutdown_absorb("rcu_torture_shuffle");
1248         } while (!kthread_should_stop());
1249         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
1250         return 0;
1251 }
1252
1253 /* Cause the rcutorture test to "stutter", starting and stopping all
1254  * threads periodically.
1255  */
1256 static int
1257 rcu_torture_stutter(void *arg)
1258 {
1259         VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
1260         do {
1261                 schedule_timeout_interruptible(stutter * HZ);
1262                 stutter_pause_test = 1;
1263                 if (!kthread_should_stop())
1264                         schedule_timeout_interruptible(stutter * HZ);
1265                 stutter_pause_test = 0;
1266                 rcutorture_shutdown_absorb("rcu_torture_stutter");
1267         } while (!kthread_should_stop());
1268         VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
1269         return 0;
1270 }
1271
1272 static inline void
1273 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
1274 {
1275         pr_alert("%s" TORTURE_FLAG
1276                  "--- %s: nreaders=%d nfakewriters=%d "
1277                  "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1278                  "shuffle_interval=%d stutter=%d irqreader=%d "
1279                  "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1280                  "test_boost=%d/%d test_boost_interval=%d "
1281                  "test_boost_duration=%d shutdown_secs=%d "
1282                  "stall_cpu=%d stall_cpu_holdoff=%d "
1283                  "n_barrier_cbs=%d "
1284                  "onoff_interval=%d onoff_holdoff=%d\n",
1285                  torture_type, tag, nrealreaders, nfakewriters,
1286                  stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1287                  stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1288                  test_boost, cur_ops->can_boost,
1289                  test_boost_interval, test_boost_duration, shutdown_secs,
1290                  stall_cpu, stall_cpu_holdoff,
1291                  n_barrier_cbs,
1292                  onoff_interval, onoff_holdoff);
1293 }
1294
1295 static struct notifier_block rcutorture_shutdown_nb = {
1296         .notifier_call = rcutorture_shutdown_notify,
1297 };
1298
1299 static void rcutorture_booster_cleanup(int cpu)
1300 {
1301         struct task_struct *t;
1302
1303         if (boost_tasks[cpu] == NULL)
1304                 return;
1305         mutex_lock(&boost_mutex);
1306         VERBOSE_PRINTK_STRING("Stopping rcu_torture_boost task");
1307         t = boost_tasks[cpu];
1308         boost_tasks[cpu] = NULL;
1309         mutex_unlock(&boost_mutex);
1310
1311         /* This must be outside of the mutex, otherwise deadlock! */
1312         kthread_stop(t);
1313         boost_tasks[cpu] = NULL;
1314 }
1315
1316 static int rcutorture_booster_init(int cpu)
1317 {
1318         int retval;
1319
1320         if (boost_tasks[cpu] != NULL)
1321                 return 0;  /* Already created, nothing more to do. */
1322
1323         /* Don't allow time recalculation while creating a new task. */
1324         mutex_lock(&boost_mutex);
1325         VERBOSE_PRINTK_STRING("Creating rcu_torture_boost task");
1326         boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1327                                                   cpu_to_node(cpu),
1328                                                   "rcu_torture_boost");
1329         if (IS_ERR(boost_tasks[cpu])) {
1330                 retval = PTR_ERR(boost_tasks[cpu]);
1331                 VERBOSE_PRINTK_STRING("rcu_torture_boost task create failed");
1332                 n_rcu_torture_boost_ktrerror++;
1333                 boost_tasks[cpu] = NULL;
1334                 mutex_unlock(&boost_mutex);
1335                 return retval;
1336         }
1337         kthread_bind(boost_tasks[cpu], cpu);
1338         wake_up_process(boost_tasks[cpu]);
1339         mutex_unlock(&boost_mutex);
1340         return 0;
1341 }
1342
1343 /*
1344  * Cause the rcutorture test to shutdown the system after the test has
1345  * run for the time specified by the shutdown_secs module parameter.
1346  */
1347 static int
1348 rcu_torture_shutdown(void *arg)
1349 {
1350         long delta;
1351         unsigned long jiffies_snap;
1352
1353         VERBOSE_PRINTK_STRING("rcu_torture_shutdown task started");
1354         jiffies_snap = ACCESS_ONCE(jiffies);
1355         while (ULONG_CMP_LT(jiffies_snap, shutdown_time) &&
1356                !kthread_should_stop()) {
1357                 delta = shutdown_time - jiffies_snap;
1358                 if (verbose)
1359                         pr_alert("%s" TORTURE_FLAG
1360                                  "rcu_torture_shutdown task: %lu jiffies remaining\n",
1361                                  torture_type, delta);
1362                 schedule_timeout_interruptible(delta);
1363                 jiffies_snap = ACCESS_ONCE(jiffies);
1364         }
1365         if (kthread_should_stop()) {
1366                 VERBOSE_PRINTK_STRING("rcu_torture_shutdown task stopping");
1367                 return 0;
1368         }
1369
1370         /* OK, shut down the system. */
1371
1372         VERBOSE_PRINTK_STRING("rcu_torture_shutdown task shutting down system");
1373         shutdown_task = NULL;   /* Avoid self-kill deadlock. */
1374         rcu_torture_cleanup();  /* Get the success/failure message. */
1375         kernel_power_off();     /* Shut down the system. */
1376         return 0;
1377 }
1378
1379 #ifdef CONFIG_HOTPLUG_CPU
1380
1381 /*
1382  * Execute random CPU-hotplug operations at the interval specified
1383  * by the onoff_interval.
1384  */
1385 static int
1386 rcu_torture_onoff(void *arg)
1387 {
1388         int cpu;
1389         unsigned long delta;
1390         int maxcpu = -1;
1391         DEFINE_RCU_RANDOM(rand);
1392         int ret;
1393         unsigned long starttime;
1394
1395         VERBOSE_PRINTK_STRING("rcu_torture_onoff task started");
1396         for_each_online_cpu(cpu)
1397                 maxcpu = cpu;
1398         WARN_ON(maxcpu < 0);
1399         if (onoff_holdoff > 0) {
1400                 VERBOSE_PRINTK_STRING("rcu_torture_onoff begin holdoff");
1401                 schedule_timeout_interruptible(onoff_holdoff * HZ);
1402                 VERBOSE_PRINTK_STRING("rcu_torture_onoff end holdoff");
1403         }
1404         while (!kthread_should_stop()) {
1405                 cpu = (rcu_random(&rand) >> 4) % (maxcpu + 1);
1406                 if (cpu_online(cpu) && cpu_is_hotpluggable(cpu)) {
1407                         if (verbose)
1408                                 pr_alert("%s" TORTURE_FLAG
1409                                          "rcu_torture_onoff task: offlining %d\n",
1410                                          torture_type, cpu);
1411                         starttime = jiffies;
1412                         n_offline_attempts++;
1413                         ret = cpu_down(cpu);
1414                         if (ret) {
1415                                 if (verbose)
1416                                         pr_alert("%s" TORTURE_FLAG
1417                                                  "rcu_torture_onoff task: offline %d failed: errno %d\n",
1418                                                  torture_type, cpu, ret);
1419                         } else {
1420                                 if (verbose)
1421                                         pr_alert("%s" TORTURE_FLAG
1422                                                  "rcu_torture_onoff task: offlined %d\n",
1423                                                  torture_type, cpu);
1424                                 n_offline_successes++;
1425                                 delta = jiffies - starttime;
1426                                 sum_offline += delta;
1427                                 if (min_offline < 0) {
1428                                         min_offline = delta;
1429                                         max_offline = delta;
1430                                 }
1431                                 if (min_offline > delta)
1432                                         min_offline = delta;
1433                                 if (max_offline < delta)
1434                                         max_offline = delta;
1435                         }
1436                 } else if (cpu_is_hotpluggable(cpu)) {
1437                         if (verbose)
1438                                 pr_alert("%s" TORTURE_FLAG
1439                                          "rcu_torture_onoff task: onlining %d\n",
1440                                          torture_type, cpu);
1441                         starttime = jiffies;
1442                         n_online_attempts++;
1443                         ret = cpu_up(cpu);
1444                         if (ret) {
1445                                 if (verbose)
1446                                         pr_alert("%s" TORTURE_FLAG
1447                                                  "rcu_torture_onoff task: online %d failed: errno %d\n",
1448                                                  torture_type, cpu, ret);
1449                         } else {
1450                                 if (verbose)
1451                                         pr_alert("%s" TORTURE_FLAG
1452                                                  "rcu_torture_onoff task: onlined %d\n",
1453                                                  torture_type, cpu);
1454                                 n_online_successes++;
1455                                 delta = jiffies - starttime;
1456                                 sum_online += delta;
1457                                 if (min_online < 0) {
1458                                         min_online = delta;
1459                                         max_online = delta;
1460                                 }
1461                                 if (min_online > delta)
1462                                         min_online = delta;
1463                                 if (max_online < delta)
1464                                         max_online = delta;
1465                         }
1466                 }
1467                 schedule_timeout_interruptible(onoff_interval * HZ);
1468         }
1469         VERBOSE_PRINTK_STRING("rcu_torture_onoff task stopping");
1470         return 0;
1471 }
1472
1473 static int
1474 rcu_torture_onoff_init(void)
1475 {
1476         int ret;
1477
1478         if (onoff_interval <= 0)
1479                 return 0;
1480         onoff_task = kthread_run(rcu_torture_onoff, NULL, "rcu_torture_onoff");
1481         if (IS_ERR(onoff_task)) {
1482                 ret = PTR_ERR(onoff_task);
1483                 onoff_task = NULL;
1484                 return ret;
1485         }
1486         return 0;
1487 }
1488
1489 static void rcu_torture_onoff_cleanup(void)
1490 {
1491         if (onoff_task == NULL)
1492                 return;
1493         VERBOSE_PRINTK_STRING("Stopping rcu_torture_onoff task");
1494         kthread_stop(onoff_task);
1495         onoff_task = NULL;
1496 }
1497
1498 #else /* #ifdef CONFIG_HOTPLUG_CPU */
1499
1500 static int
1501 rcu_torture_onoff_init(void)
1502 {
1503         return 0;
1504 }
1505
1506 static void rcu_torture_onoff_cleanup(void)
1507 {
1508 }
1509
1510 #endif /* #else #ifdef CONFIG_HOTPLUG_CPU */
1511
1512 /*
1513  * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
1514  * induces a CPU stall for the time specified by stall_cpu.
1515  */
1516 static int rcu_torture_stall(void *args)
1517 {
1518         unsigned long stop_at;
1519
1520         VERBOSE_PRINTK_STRING("rcu_torture_stall task started");
1521         if (stall_cpu_holdoff > 0) {
1522                 VERBOSE_PRINTK_STRING("rcu_torture_stall begin holdoff");
1523                 schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1524                 VERBOSE_PRINTK_STRING("rcu_torture_stall end holdoff");
1525         }
1526         if (!kthread_should_stop()) {
1527                 stop_at = get_seconds() + stall_cpu;
1528                 /* RCU CPU stall is expected behavior in following code. */
1529                 pr_alert("rcu_torture_stall start.\n");
1530                 rcu_read_lock();
1531                 preempt_disable();
1532                 while (ULONG_CMP_LT(get_seconds(), stop_at))
1533                         continue;  /* Induce RCU CPU stall warning. */
1534                 preempt_enable();
1535                 rcu_read_unlock();
1536                 pr_alert("rcu_torture_stall end.\n");
1537         }
1538         rcutorture_shutdown_absorb("rcu_torture_stall");
1539         while (!kthread_should_stop())
1540                 schedule_timeout_interruptible(10 * HZ);
1541         return 0;
1542 }
1543
1544 /* Spawn CPU-stall kthread, if stall_cpu specified. */
1545 static int __init rcu_torture_stall_init(void)
1546 {
1547         int ret;
1548
1549         if (stall_cpu <= 0)
1550                 return 0;
1551         stall_task = kthread_run(rcu_torture_stall, NULL, "rcu_torture_stall");
1552         if (IS_ERR(stall_task)) {
1553                 ret = PTR_ERR(stall_task);
1554                 stall_task = NULL;
1555                 return ret;
1556         }
1557         return 0;
1558 }
1559
1560 /* Clean up after the CPU-stall kthread, if one was spawned. */
1561 static void rcu_torture_stall_cleanup(void)
1562 {
1563         if (stall_task == NULL)
1564                 return;
1565         VERBOSE_PRINTK_STRING("Stopping rcu_torture_stall_task.");
1566         kthread_stop(stall_task);
1567         stall_task = NULL;
1568 }
1569
1570 /* Callback function for RCU barrier testing. */
1571 void rcu_torture_barrier_cbf(struct rcu_head *rcu)
1572 {
1573         atomic_inc(&barrier_cbs_invoked);
1574 }
1575
1576 /* kthread function to register callbacks used to test RCU barriers. */
1577 static int rcu_torture_barrier_cbs(void *arg)
1578 {
1579         long myid = (long)arg;
1580         bool lastphase = 0;
1581         struct rcu_head rcu;
1582
1583         init_rcu_head_on_stack(&rcu);
1584         VERBOSE_PRINTK_STRING("rcu_torture_barrier_cbs task started");
1585         set_user_nice(current, 19);
1586         do {
1587                 wait_event(barrier_cbs_wq[myid],
1588                            barrier_phase != lastphase ||
1589                            kthread_should_stop() ||
1590                            fullstop != FULLSTOP_DONTSTOP);
1591                 lastphase = barrier_phase;
1592                 smp_mb(); /* ensure barrier_phase load before ->call(). */
1593                 if (kthread_should_stop() || fullstop != FULLSTOP_DONTSTOP)
1594                         break;
1595                 cur_ops->call(&rcu, rcu_torture_barrier_cbf);
1596                 if (atomic_dec_and_test(&barrier_cbs_count))
1597                         wake_up(&barrier_wq);
1598         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1599         VERBOSE_PRINTK_STRING("rcu_torture_barrier_cbs task stopping");
1600         rcutorture_shutdown_absorb("rcu_torture_barrier_cbs");
1601         while (!kthread_should_stop())
1602                 schedule_timeout_interruptible(1);
1603         cur_ops->cb_barrier();
1604         destroy_rcu_head_on_stack(&rcu);
1605         return 0;
1606 }
1607
1608 /* kthread function to drive and coordinate RCU barrier testing. */
1609 static int rcu_torture_barrier(void *arg)
1610 {
1611         int i;
1612
1613         VERBOSE_PRINTK_STRING("rcu_torture_barrier task starting");
1614         do {
1615                 atomic_set(&barrier_cbs_invoked, 0);
1616                 atomic_set(&barrier_cbs_count, n_barrier_cbs);
1617                 smp_mb(); /* Ensure barrier_phase after prior assignments. */
1618                 barrier_phase = !barrier_phase;
1619                 for (i = 0; i < n_barrier_cbs; i++)
1620                         wake_up(&barrier_cbs_wq[i]);
1621                 wait_event(barrier_wq,
1622                            atomic_read(&barrier_cbs_count) == 0 ||
1623                            kthread_should_stop() ||
1624                            fullstop != FULLSTOP_DONTSTOP);
1625                 if (kthread_should_stop() || fullstop != FULLSTOP_DONTSTOP)
1626                         break;
1627                 n_barrier_attempts++;
1628                 cur_ops->cb_barrier();
1629                 if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
1630                         n_rcu_torture_barrier_error++;
1631                         WARN_ON_ONCE(1);
1632                 }
1633                 n_barrier_successes++;
1634                 schedule_timeout_interruptible(HZ / 10);
1635         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1636         VERBOSE_PRINTK_STRING("rcu_torture_barrier task stopping");
1637         rcutorture_shutdown_absorb("rcu_torture_barrier");
1638         while (!kthread_should_stop())
1639                 schedule_timeout_interruptible(1);
1640         return 0;
1641 }
1642
1643 /* Initialize RCU barrier testing. */
1644 static int rcu_torture_barrier_init(void)
1645 {
1646         int i;
1647         int ret;
1648
1649         if (n_barrier_cbs == 0)
1650                 return 0;
1651         if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
1652                 pr_alert("%s" TORTURE_FLAG
1653                          " Call or barrier ops missing for %s,\n",
1654                          torture_type, cur_ops->name);
1655                 pr_alert("%s" TORTURE_FLAG
1656                          " RCU barrier testing omitted from run.\n",
1657                          torture_type);
1658                 return 0;
1659         }
1660         atomic_set(&barrier_cbs_count, 0);
1661         atomic_set(&barrier_cbs_invoked, 0);
1662         barrier_cbs_tasks =
1663                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_tasks[0]),
1664                         GFP_KERNEL);
1665         barrier_cbs_wq =
1666                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_wq[0]),
1667                         GFP_KERNEL);
1668         if (barrier_cbs_tasks == NULL || !barrier_cbs_wq)
1669                 return -ENOMEM;
1670         for (i = 0; i < n_barrier_cbs; i++) {
1671                 init_waitqueue_head(&barrier_cbs_wq[i]);
1672                 barrier_cbs_tasks[i] = kthread_run(rcu_torture_barrier_cbs,
1673                                                    (void *)(long)i,
1674                                                    "rcu_torture_barrier_cbs");
1675                 if (IS_ERR(barrier_cbs_tasks[i])) {
1676                         ret = PTR_ERR(barrier_cbs_tasks[i]);
1677                         VERBOSE_PRINTK_ERRSTRING("Failed to create rcu_torture_barrier_cbs");
1678                         barrier_cbs_tasks[i] = NULL;
1679                         return ret;
1680                 }
1681         }
1682         barrier_task = kthread_run(rcu_torture_barrier, NULL,
1683                                    "rcu_torture_barrier");
1684         if (IS_ERR(barrier_task)) {
1685                 ret = PTR_ERR(barrier_task);
1686                 VERBOSE_PRINTK_ERRSTRING("Failed to create rcu_torture_barrier");
1687                 barrier_task = NULL;
1688         }
1689         return 0;
1690 }
1691
1692 /* Clean up after RCU barrier testing. */
1693 static void rcu_torture_barrier_cleanup(void)
1694 {
1695         int i;
1696
1697         if (barrier_task != NULL) {
1698                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_barrier task");
1699                 kthread_stop(barrier_task);
1700                 barrier_task = NULL;
1701         }
1702         if (barrier_cbs_tasks != NULL) {
1703                 for (i = 0; i < n_barrier_cbs; i++) {
1704                         if (barrier_cbs_tasks[i] != NULL) {
1705                                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_barrier_cbs task");
1706                                 kthread_stop(barrier_cbs_tasks[i]);
1707                                 barrier_cbs_tasks[i] = NULL;
1708                         }
1709                 }
1710                 kfree(barrier_cbs_tasks);
1711                 barrier_cbs_tasks = NULL;
1712         }
1713         if (barrier_cbs_wq != NULL) {
1714                 kfree(barrier_cbs_wq);
1715                 barrier_cbs_wq = NULL;
1716         }
1717 }
1718
1719 static int rcutorture_cpu_notify(struct notifier_block *self,
1720                                  unsigned long action, void *hcpu)
1721 {
1722         long cpu = (long)hcpu;
1723
1724         switch (action) {
1725         case CPU_ONLINE:
1726         case CPU_DOWN_FAILED:
1727                 (void)rcutorture_booster_init(cpu);
1728                 break;
1729         case CPU_DOWN_PREPARE:
1730                 rcutorture_booster_cleanup(cpu);
1731                 break;
1732         default:
1733                 break;
1734         }
1735         return NOTIFY_OK;
1736 }
1737
1738 static struct notifier_block rcutorture_cpu_nb = {
1739         .notifier_call = rcutorture_cpu_notify,
1740 };
1741
1742 static void
1743 rcu_torture_cleanup(void)
1744 {
1745         int i;
1746
1747         mutex_lock(&fullstop_mutex);
1748         rcutorture_record_test_transition();
1749         if (fullstop == FULLSTOP_SHUTDOWN) {
1750                 pr_warn(/* but going down anyway, so... */
1751                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
1752                 mutex_unlock(&fullstop_mutex);
1753                 schedule_timeout_uninterruptible(10);
1754                 if (cur_ops->cb_barrier != NULL)
1755                         cur_ops->cb_barrier();
1756                 return;
1757         }
1758         fullstop = FULLSTOP_RMMOD;
1759         mutex_unlock(&fullstop_mutex);
1760         unregister_reboot_notifier(&rcutorture_shutdown_nb);
1761         rcu_torture_barrier_cleanup();
1762         rcu_torture_stall_cleanup();
1763         if (stutter_task) {
1764                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
1765                 kthread_stop(stutter_task);
1766         }
1767         stutter_task = NULL;
1768         if (shuffler_task) {
1769                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
1770                 kthread_stop(shuffler_task);
1771                 free_cpumask_var(shuffle_tmp_mask);
1772         }
1773         shuffler_task = NULL;
1774
1775         if (writer_task) {
1776                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
1777                 kthread_stop(writer_task);
1778         }
1779         writer_task = NULL;
1780
1781         if (reader_tasks) {
1782                 for (i = 0; i < nrealreaders; i++) {
1783                         if (reader_tasks[i]) {
1784                                 VERBOSE_PRINTK_STRING(
1785                                         "Stopping rcu_torture_reader task");
1786                                 kthread_stop(reader_tasks[i]);
1787                         }
1788                         reader_tasks[i] = NULL;
1789                 }
1790                 kfree(reader_tasks);
1791                 reader_tasks = NULL;
1792         }
1793         rcu_torture_current = NULL;
1794
1795         if (fakewriter_tasks) {
1796                 for (i = 0; i < nfakewriters; i++) {
1797                         if (fakewriter_tasks[i]) {
1798                                 VERBOSE_PRINTK_STRING(
1799                                         "Stopping rcu_torture_fakewriter task");
1800                                 kthread_stop(fakewriter_tasks[i]);
1801                         }
1802                         fakewriter_tasks[i] = NULL;
1803                 }
1804                 kfree(fakewriter_tasks);
1805                 fakewriter_tasks = NULL;
1806         }
1807
1808         if (stats_task) {
1809                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
1810                 kthread_stop(stats_task);
1811         }
1812         stats_task = NULL;
1813
1814         if (fqs_task) {
1815                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_fqs task");
1816                 kthread_stop(fqs_task);
1817         }
1818         fqs_task = NULL;
1819         if ((test_boost == 1 && cur_ops->can_boost) ||
1820             test_boost == 2) {
1821                 unregister_cpu_notifier(&rcutorture_cpu_nb);
1822                 for_each_possible_cpu(i)
1823                         rcutorture_booster_cleanup(i);
1824         }
1825         if (shutdown_task != NULL) {
1826                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shutdown task");
1827                 kthread_stop(shutdown_task);
1828         }
1829         shutdown_task = NULL;
1830         rcu_torture_onoff_cleanup();
1831
1832         /* Wait for all RCU callbacks to fire.  */
1833
1834         if (cur_ops->cb_barrier != NULL)
1835                 cur_ops->cb_barrier();
1836
1837         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1838
1839         if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
1840                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1841         else if (n_online_successes != n_online_attempts ||
1842                  n_offline_successes != n_offline_attempts)
1843                 rcu_torture_print_module_parms(cur_ops,
1844                                                "End of test: RCU_HOTPLUG");
1845         else
1846                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1847 }
1848
1849 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1850 static void rcu_torture_leak_cb(struct rcu_head *rhp)
1851 {
1852 }
1853
1854 static void rcu_torture_err_cb(struct rcu_head *rhp)
1855 {
1856         /*
1857          * This -might- happen due to race conditions, but is unlikely.
1858          * The scenario that leads to this happening is that the
1859          * first of the pair of duplicate callbacks is queued,
1860          * someone else starts a grace period that includes that
1861          * callback, then the second of the pair must wait for the
1862          * next grace period.  Unlikely, but can happen.  If it
1863          * does happen, the debug-objects subsystem won't have splatted.
1864          */
1865         pr_alert("rcutorture: duplicated callback was invoked.\n");
1866 }
1867 #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1868
1869 /*
1870  * Verify that double-free causes debug-objects to complain, but only
1871  * if CONFIG_DEBUG_OBJECTS_RCU_HEAD=y.  Otherwise, say that the test
1872  * cannot be carried out.
1873  */
1874 static void rcu_test_debug_objects(void)
1875 {
1876 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1877         struct rcu_head rh1;
1878         struct rcu_head rh2;
1879
1880         init_rcu_head_on_stack(&rh1);
1881         init_rcu_head_on_stack(&rh2);
1882         pr_alert("rcutorture: WARN: Duplicate call_rcu() test starting.\n");
1883
1884         /* Try to queue the rh2 pair of callbacks for the same grace period. */
1885         preempt_disable(); /* Prevent preemption from interrupting test. */
1886         rcu_read_lock(); /* Make it impossible to finish a grace period. */
1887         call_rcu(&rh1, rcu_torture_leak_cb); /* Start grace period. */
1888         local_irq_disable(); /* Make it harder to start a new grace period. */
1889         call_rcu(&rh2, rcu_torture_leak_cb);
1890         call_rcu(&rh2, rcu_torture_err_cb); /* Duplicate callback. */
1891         local_irq_enable();
1892         rcu_read_unlock();
1893         preempt_enable();
1894
1895         /* Wait for them all to get done so we can safely return. */
1896         rcu_barrier();
1897         pr_alert("rcutorture: WARN: Duplicate call_rcu() test complete.\n");
1898         destroy_rcu_head_on_stack(&rh1);
1899         destroy_rcu_head_on_stack(&rh2);
1900 #else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1901         pr_alert("rcutorture: !CONFIG_DEBUG_OBJECTS_RCU_HEAD, not testing duplicate call_rcu()\n");
1902 #endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1903 }
1904
1905 static int __init
1906 rcu_torture_init(void)
1907 {
1908         int i;
1909         int cpu;
1910         int firsterr = 0;
1911         int retval;
1912         static struct rcu_torture_ops *torture_ops[] = {
1913                 &rcu_ops, &rcu_bh_ops, &srcu_ops, &sched_ops,
1914         };
1915
1916         mutex_lock(&fullstop_mutex);
1917
1918         /* Process args and tell the world that the torturer is on the job. */
1919         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1920                 cur_ops = torture_ops[i];
1921                 if (strcmp(torture_type, cur_ops->name) == 0)
1922                         break;
1923         }
1924         if (i == ARRAY_SIZE(torture_ops)) {
1925                 pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
1926                          torture_type);
1927                 pr_alert("rcu-torture types:");
1928                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1929                         pr_alert(" %s", torture_ops[i]->name);
1930                 pr_alert("\n");
1931                 mutex_unlock(&fullstop_mutex);
1932                 return -EINVAL;
1933         }
1934         if (cur_ops->fqs == NULL && fqs_duration != 0) {
1935                 pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
1936                 fqs_duration = 0;
1937         }
1938         if (cur_ops->init)
1939                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1940
1941         if (nreaders >= 0)
1942                 nrealreaders = nreaders;
1943         else
1944                 nrealreaders = 2 * num_online_cpus();
1945         rcu_torture_print_module_parms(cur_ops, "Start of test");
1946         fullstop = FULLSTOP_DONTSTOP;
1947
1948         /* Set up the freelist. */
1949
1950         INIT_LIST_HEAD(&rcu_torture_freelist);
1951         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1952                 rcu_tortures[i].rtort_mbtest = 0;
1953                 list_add_tail(&rcu_tortures[i].rtort_free,
1954                               &rcu_torture_freelist);
1955         }
1956
1957         /* Initialize the statistics so that each run gets its own numbers. */
1958
1959         rcu_torture_current = NULL;
1960         rcu_torture_current_version = 0;
1961         atomic_set(&n_rcu_torture_alloc, 0);
1962         atomic_set(&n_rcu_torture_alloc_fail, 0);
1963         atomic_set(&n_rcu_torture_free, 0);
1964         atomic_set(&n_rcu_torture_mberror, 0);
1965         atomic_set(&n_rcu_torture_error, 0);
1966         n_rcu_torture_barrier_error = 0;
1967         n_rcu_torture_boost_ktrerror = 0;
1968         n_rcu_torture_boost_rterror = 0;
1969         n_rcu_torture_boost_failure = 0;
1970         n_rcu_torture_boosts = 0;
1971         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1972                 atomic_set(&rcu_torture_wcount[i], 0);
1973         for_each_possible_cpu(cpu) {
1974                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1975                         per_cpu(rcu_torture_count, cpu)[i] = 0;
1976                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
1977                 }
1978         }
1979
1980         /* Start up the kthreads. */
1981
1982         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
1983         writer_task = kthread_create(rcu_torture_writer, NULL,
1984                                      "rcu_torture_writer");
1985         if (IS_ERR(writer_task)) {
1986                 firsterr = PTR_ERR(writer_task);
1987                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
1988                 writer_task = NULL;
1989                 goto unwind;
1990         }
1991         wake_up_process(writer_task);
1992         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1993                                    GFP_KERNEL);
1994         if (fakewriter_tasks == NULL) {
1995                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1996                 firsterr = -ENOMEM;
1997                 goto unwind;
1998         }
1999         for (i = 0; i < nfakewriters; i++) {
2000                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
2001                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
2002                                                   "rcu_torture_fakewriter");
2003                 if (IS_ERR(fakewriter_tasks[i])) {
2004                         firsterr = PTR_ERR(fakewriter_tasks[i]);
2005                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
2006                         fakewriter_tasks[i] = NULL;
2007                         goto unwind;
2008                 }
2009         }
2010         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
2011                                GFP_KERNEL);
2012         if (reader_tasks == NULL) {
2013                 VERBOSE_PRINTK_ERRSTRING("out of memory");
2014                 firsterr = -ENOMEM;
2015                 goto unwind;
2016         }
2017         for (i = 0; i < nrealreaders; i++) {
2018                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
2019                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
2020                                               "rcu_torture_reader");
2021                 if (IS_ERR(reader_tasks[i])) {
2022                         firsterr = PTR_ERR(reader_tasks[i]);
2023                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
2024                         reader_tasks[i] = NULL;
2025                         goto unwind;
2026                 }
2027         }
2028         if (stat_interval > 0) {
2029                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
2030                 stats_task = kthread_run(rcu_torture_stats, NULL,
2031                                         "rcu_torture_stats");
2032                 if (IS_ERR(stats_task)) {
2033                         firsterr = PTR_ERR(stats_task);
2034                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
2035                         stats_task = NULL;
2036                         goto unwind;
2037                 }
2038         }
2039         if (test_no_idle_hz) {
2040                 rcu_idle_cpu = num_online_cpus() - 1;
2041
2042                 if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
2043                         firsterr = -ENOMEM;
2044                         VERBOSE_PRINTK_ERRSTRING("Failed to alloc mask");
2045                         goto unwind;
2046                 }
2047
2048                 /* Create the shuffler thread */
2049                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
2050                                           "rcu_torture_shuffle");
2051                 if (IS_ERR(shuffler_task)) {
2052                         free_cpumask_var(shuffle_tmp_mask);
2053                         firsterr = PTR_ERR(shuffler_task);
2054                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
2055                         shuffler_task = NULL;
2056                         goto unwind;
2057                 }
2058         }
2059         if (stutter < 0)
2060                 stutter = 0;
2061         if (stutter) {
2062                 /* Create the stutter thread */
2063                 stutter_task = kthread_run(rcu_torture_stutter, NULL,
2064                                           "rcu_torture_stutter");
2065                 if (IS_ERR(stutter_task)) {
2066                         firsterr = PTR_ERR(stutter_task);
2067                         VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
2068                         stutter_task = NULL;
2069                         goto unwind;
2070                 }
2071         }
2072         if (fqs_duration < 0)
2073                 fqs_duration = 0;
2074         if (fqs_duration) {
2075                 /* Create the stutter thread */
2076                 fqs_task = kthread_run(rcu_torture_fqs, NULL,
2077                                        "rcu_torture_fqs");
2078                 if (IS_ERR(fqs_task)) {
2079                         firsterr = PTR_ERR(fqs_task);
2080                         VERBOSE_PRINTK_ERRSTRING("Failed to create fqs");
2081                         fqs_task = NULL;
2082                         goto unwind;
2083                 }
2084         }
2085         if (test_boost_interval < 1)
2086                 test_boost_interval = 1;
2087         if (test_boost_duration < 2)
2088                 test_boost_duration = 2;
2089         if ((test_boost == 1 && cur_ops->can_boost) ||
2090             test_boost == 2) {
2091
2092                 boost_starttime = jiffies + test_boost_interval * HZ;
2093                 register_cpu_notifier(&rcutorture_cpu_nb);
2094                 for_each_possible_cpu(i) {
2095                         if (cpu_is_offline(i))
2096                                 continue;  /* Heuristic: CPU can go offline. */
2097                         retval = rcutorture_booster_init(i);
2098                         if (retval < 0) {
2099                                 firsterr = retval;
2100                                 goto unwind;
2101                         }
2102                 }
2103         }
2104         if (shutdown_secs > 0) {
2105                 shutdown_time = jiffies + shutdown_secs * HZ;
2106                 shutdown_task = kthread_create(rcu_torture_shutdown, NULL,
2107                                                "rcu_torture_shutdown");
2108                 if (IS_ERR(shutdown_task)) {
2109                         firsterr = PTR_ERR(shutdown_task);
2110                         VERBOSE_PRINTK_ERRSTRING("Failed to create shutdown");
2111                         shutdown_task = NULL;
2112                         goto unwind;
2113                 }
2114                 wake_up_process(shutdown_task);
2115         }
2116         i = rcu_torture_onoff_init();
2117         if (i != 0) {
2118                 firsterr = i;
2119                 goto unwind;
2120         }
2121         register_reboot_notifier(&rcutorture_shutdown_nb);
2122         i = rcu_torture_stall_init();
2123         if (i != 0) {
2124                 firsterr = i;
2125                 goto unwind;
2126         }
2127         retval = rcu_torture_barrier_init();
2128         if (retval != 0) {
2129                 firsterr = retval;
2130                 goto unwind;
2131         }
2132         if (object_debug)
2133                 rcu_test_debug_objects();
2134         rcutorture_record_test_transition();
2135         mutex_unlock(&fullstop_mutex);
2136         return 0;
2137
2138 unwind:
2139         mutex_unlock(&fullstop_mutex);
2140         rcu_torture_cleanup();
2141         return firsterr;
2142 }
2143
2144 module_init(rcu_torture_init);
2145 module_exit(rcu_torture_cleanup);