kernel/rcutorture.c

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