kernel/rcutorture.c

   1 /*
   2  * Read-Copy Update module-based torture test facility
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  17  *
  18  * Copyright (C) IBM Corporation, 2005, 2006
  19  *
  20  * Authors: Paul E. McKenney <paulmck@us.ibm.com>
  21  *        Josh Triplett <josh@freedesktop.org>
  22  *
  23  * See also:  Documentation/RCU/torture.txt
  24  */
  25 #include <linux/types.h>
  26 #include <linux/kernel.h>
  27 #include <linux/init.h>
  28 #include <linux/module.h>
  29 #include <linux/kthread.h>
  30 #include <linux/err.h>
  31 #include <linux/spinlock.h>
  32 #include <linux/smp.h>
  33 #include <linux/rcupdate.h>
  34 #include <linux/interrupt.h>
  35 #include <linux/sched.h>
  36 #include <linux/atomic.h>
  37 #include <linux/bitops.h>
  38 #include <linux/completion.h>
  39 #include <linux/moduleparam.h>
  40 #include <linux/percpu.h>
  41 #include <linux/notifier.h>
  42 #include <linux/reboot.h>
  43 #include <linux/freezer.h>
  44 #include <linux/cpu.h>
  45 #include <linux/delay.h>
  46 #include <linux/stat.h>
  47 #include <linux/srcu.h>
  48 #include <linux/slab.h>
  49 #include <linux/trace_clock.h>
  50 #include <asm/byteorder.h>
  51
  52 MODULE_LICENSE("GPL");
  53 MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and Josh Triplett <josh@freedesktop.org>");
  54
  55 static int nreaders = -1;       /* # reader threads, defaults to 2*ncpus */
  56 static int nfakewriters = 4;    /* # fake writer threads */
  57 static int stat_interval = 60;  /* Interval between stats, in seconds. */
  58                                 /*  Zero means "only at end of test". */
  59 static bool verbose;            /* Print more debug info. */
  60 static bool test_no_idle_hz = true;
  61                                 /* Test RCU support for tickless idle CPUs. */
  62 static int shuffle_interval = 3; /* Interval between shuffles (in sec)*/
  63 static int stutter = 5;         /* Start/stop testing interval (in sec) */
  64 static int irqreader = 1;       /* RCU readers from irq (timers). */
  65 static int fqs_duration;        /* Duration of bursts (us), 0 to disable. */
  66 static int fqs_holdoff;         /* Hold time within burst (us). */
  67 static int fqs_stutter = 3;     /* Wait time between bursts (s). */
  68 static int n_barrier_cbs;       /* Number of callbacks to test RCU barriers. */
  69 static int onoff_interval;      /* Wait time between CPU hotplugs, 0=disable. */
  70 static int onoff_holdoff;       /* Seconds after boot before CPU hotplugs. */
  71 static int shutdown_secs;       /* Shutdown time (s).  <=0 for no shutdown. */
  72 static int stall_cpu;           /* CPU-stall duration (s).  0 for no stall. */
  73 static int stall_cpu_holdoff = 10; /* Time to wait until stall (s).  */
  74 static int test_boost = 1;      /* Test RCU prio boost: 0=no, 1=maybe, 2=yes. */
  75 static int test_boost_interval = 7; /* Interval between boost tests, seconds. */
  76 static int test_boost_duration = 4; /* Duration of each boost test, seconds. */
  77 static char *torture_type = "rcu"; /* What RCU implementation to torture. */
  78
  79 module_param(nreaders, int, 0444);
  80 MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
  81 module_param(nfakewriters, int, 0444);
  82 MODULE_PARM_DESC(nfakewriters, "Number of RCU fake writer threads");
  83 module_param(stat_interval, int, 0644);
  84 MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
  85 module_param(verbose, bool, 0444);
  86 MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
  87 module_param(test_no_idle_hz, bool, 0444);
  88 MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
  89 module_param(shuffle_interval, int, 0444);
  90 MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
  91 module_param(stutter, int, 0444);
  92 MODULE_PARM_DESC(stutter, "Number of seconds to run/halt test");
  93 module_param(irqreader, int, 0444);
  94 MODULE_PARM_DESC(irqreader, "Allow RCU readers from irq handlers");
  95 module_param(fqs_duration, int, 0444);
  96 MODULE_PARM_DESC(fqs_duration, "Duration of fqs bursts (us)");
  97 module_param(fqs_holdoff, int, 0444);
  98 MODULE_PARM_DESC(fqs_holdoff, "Holdoff time within fqs bursts (us)");
  99 module_param(fqs_stutter, int, 0444);
 100 MODULE_PARM_DESC(fqs_stutter, "Wait time between fqs bursts (s)");
 101 module_param(n_barrier_cbs, int, 0444);
 102 MODULE_PARM_DESC(n_barrier_cbs, "# of callbacks/kthreads for barrier testing");
 103 module_param(onoff_interval, int, 0444);
 104 MODULE_PARM_DESC(onoff_interval, "Time between CPU hotplugs (s), 0=disable");
 105 module_param(onoff_holdoff, int, 0444);
 106 MODULE_PARM_DESC(onoff_holdoff, "Time after boot before CPU hotplugs (s)");
 107 module_param(shutdown_secs, int, 0444);
 108 MODULE_PARM_DESC(shutdown_secs, "Shutdown time (s), zero to disable.");
 109 module_param(stall_cpu, int, 0444);
 110 MODULE_PARM_DESC(stall_cpu, "Stall duration (s), zero to disable.");
 111 module_param(stall_cpu_holdoff, int, 0444);
 112 MODULE_PARM_DESC(stall_cpu_holdoff, "Time to wait before starting stall (s).");
 113 module_param(test_boost, int, 0444);
 114 MODULE_PARM_DESC(test_boost, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
 115 module_param(test_boost_interval, int, 0444);
 116 MODULE_PARM_DESC(test_boost_interval, "Interval between boost tests, seconds.");
 117 module_param(test_boost_duration, int, 0444);
 118 MODULE_PARM_DESC(test_boost_duration, "Duration of each boost test, seconds.");
 119 module_param(torture_type, charp, 0444);
 120 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, srcu)");
 121
 122 #define TORTURE_FLAG "-torture:"
 123 #define PRINTK_STRING(s) \
 124         do { pr_alert("%s" TORTURE_FLAG s "\n", torture_type); } while (0)
 125 #define VERBOSE_PRINTK_STRING(s) \
 126         do { if (verbose) pr_alert("%s" TORTURE_FLAG s "\n", torture_type); } while (0)
 127 #define VERBOSE_PRINTK_ERRSTRING(s) \
 128         do { if (verbose) pr_alert("%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
 129
 130 static char printk_buf[4096];
 131
 132 static int nrealreaders;
 133 static struct task_struct *writer_task;
 134 static struct task_struct **fakewriter_tasks;
 135 static struct task_struct **reader_tasks;
 136 static struct task_struct *stats_task;
 137 static struct task_struct *shuffler_task;
 138 static struct task_struct *stutter_task;
 139 static struct task_struct *fqs_task;
 140 static struct task_struct *boost_tasks[NR_CPUS];
 141 static struct task_struct *shutdown_task;
 142 #ifdef CONFIG_HOTPLUG_CPU
 143 static struct task_struct *onoff_task;
 144 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
 145 static struct task_struct *stall_task;
 146 static struct task_struct **barrier_cbs_tasks;
 147 static struct task_struct *barrier_task;
 148
 149 #define RCU_TORTURE_PIPE_LEN 10
 150
 151 struct rcu_torture {
 152         struct rcu_head rtort_rcu;
 153         int rtort_pipe_count;
 154         struct list_head rtort_free;
 155         int rtort_mbtest;
 156 };
 157
 158 static LIST_HEAD(rcu_torture_freelist);
 159 static struct rcu_torture __rcu *rcu_torture_current;
 160 static unsigned long rcu_torture_current_version;
 161 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 162 static DEFINE_SPINLOCK(rcu_torture_lock);
 163 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
 164         { 0 };
 165 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) =
 166         { 0 };
 167 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 168 static atomic_t n_rcu_torture_alloc;
 169 static atomic_t n_rcu_torture_alloc_fail;
 170 static atomic_t n_rcu_torture_free;
 171 static atomic_t n_rcu_torture_mberror;
 172 static atomic_t n_rcu_torture_error;
 173 static long n_rcu_torture_barrier_error;
 174 static long n_rcu_torture_boost_ktrerror;
 175 static long n_rcu_torture_boost_rterror;
 176 static long n_rcu_torture_boost_failure;
 177 static long n_rcu_torture_boosts;
 178 static long n_rcu_torture_timers;
 179 static long n_offline_attempts;
 180 static long n_offline_successes;
 181 static unsigned long sum_offline;
 182 static int min_offline = -1;
 183 static int max_offline;
 184 static long n_online_attempts;
 185 static long n_online_successes;
 186 static unsigned long sum_online;
 187 static int min_online = -1;
 188 static int max_online;
 189 static long n_barrier_attempts;
 190 static long n_barrier_successes;
 191 static struct list_head rcu_torture_removed;
 192 static cpumask_var_t shuffle_tmp_mask;
 193
 194 static int stutter_pause_test;
 195
 196 #if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
 197 #define RCUTORTURE_RUNNABLE_INIT 1
 198 #else
 199 #define RCUTORTURE_RUNNABLE_INIT 0
 200 #endif
 201 int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT;
 202 module_param(rcutorture_runnable, int, 0444);
 203 MODULE_PARM_DESC(rcutorture_runnable, "Start rcutorture at boot");
 204
 205 #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
 206 #define rcu_can_boost() 1
 207 #else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 208 #define rcu_can_boost() 0
 209 #endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 210
 211 #ifdef CONFIG_RCU_TRACE
 212 static u64 notrace rcu_trace_clock_local(void)
 213 {
 214         u64 ts = trace_clock_local();
 215         unsigned long __maybe_unused ts_rem = do_div(ts, NSEC_PER_USEC);
 216         return ts;
 217 }
 218 #else /* #ifdef CONFIG_RCU_TRACE */
 219 static u64 notrace rcu_trace_clock_local(void)
 220 {
 221         return 0ULL;
 222 }
 223 #endif /* #else #ifdef CONFIG_RCU_TRACE */
 224
 225 static unsigned long shutdown_time;     /* jiffies to system shutdown. */
 226 static unsigned long boost_starttime;   /* jiffies of next boost test start. */
 227 DEFINE_MUTEX(boost_mutex);              /* protect setting boost_starttime */
 228                                         /*  and boost task create/destroy. */
 229 static atomic_t barrier_cbs_count;      /* Barrier callbacks registered. */
 230 static bool barrier_phase;              /* Test phase. */
 231 static atomic_t barrier_cbs_invoked;    /* Barrier callbacks invoked. */
 232 static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */
 233 static DECLARE_WAIT_QUEUE_HEAD(barrier_wq);
 234
 235 /* Mediate rmmod and system shutdown.  Concurrent rmmod & shutdown illegal! */
 236
 237 #define FULLSTOP_DONTSTOP 0     /* Normal operation. */
 238 #define FULLSTOP_SHUTDOWN 1     /* System shutdown with rcutorture running. */
 239 #define FULLSTOP_RMMOD    2     /* Normal rmmod of rcutorture. */
 240 static int fullstop = FULLSTOP_RMMOD;
 241 /*
 242  * Protect fullstop transitions and spawning of kthreads.
 243  */
 244 static DEFINE_MUTEX(fullstop_mutex);
 245
 246 /* Forward reference. */
 247 static void rcu_torture_cleanup(void);
 248
 249 /*
 250  * Detect and respond to a system shutdown.
 251  */
 252 static int
 253 rcutorture_shutdown_notify(struct notifier_block *unused1,
 254                            unsigned long unused2, void *unused3)
 255 {
 256         mutex_lock(&fullstop_mutex);
 257         if (fullstop == FULLSTOP_DONTSTOP)
 258                 fullstop = FULLSTOP_SHUTDOWN;
 259         else
 260                 pr_warn(/* but going down anyway, so... */
 261                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
 262         mutex_unlock(&fullstop_mutex);
 263         return NOTIFY_DONE;
 264 }
 265
 266 /*
 267  * Absorb kthreads into a kernel function that won't return, so that
 268  * they won't ever access module text or data again.
 269  */
 270 static void rcutorture_shutdown_absorb(char *title)
 271 {
 272         if (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
 273                 pr_notice(
 274                        "rcutorture thread %s parking due to system shutdown\n",
 275                        title);
 276                 schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
 277         }
 278 }
 279
 280 /*
 281  * Allocate an element from the rcu_tortures pool.
 282  */
 283 static struct rcu_torture *
 284 rcu_torture_alloc(void)
 285 {
 286         struct list_head *p;
 287
 288         spin_lock_bh(&rcu_torture_lock);
 289         if (list_empty(&rcu_torture_freelist)) {
 290                 atomic_inc(&n_rcu_torture_alloc_fail);
 291                 spin_unlock_bh(&rcu_torture_lock);
 292                 return NULL;
 293         }
 294         atomic_inc(&n_rcu_torture_alloc);
 295         p = rcu_torture_freelist.next;
 296         list_del_init(p);
 297         spin_unlock_bh(&rcu_torture_lock);
 298         return container_of(p, struct rcu_torture, rtort_free);
 299 }
 300
 301 /*
 302  * Free an element to the rcu_tortures pool.
 303  */
 304 static void
 305 rcu_torture_free(struct rcu_torture *p)
 306 {
 307         atomic_inc(&n_rcu_torture_free);
 308         spin_lock_bh(&rcu_torture_lock);
 309         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 310         spin_unlock_bh(&rcu_torture_lock);
 311 }
 312
 313 struct rcu_random_state {
 314         unsigned long rrs_state;
 315         long rrs_count;
 316 };
 317
 318 #define RCU_RANDOM_MULT 39916801  /* prime */
 319 #define RCU_RANDOM_ADD  479001701 /* prime */
 320 #define RCU_RANDOM_REFRESH 10000
 321
 322 #define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
 323
 324 /*
 325  * Crude but fast random-number generator.  Uses a linear congruential
 326  * generator, with occasional help from cpu_clock().
 327  */
 328 static unsigned long
 329 rcu_random(struct rcu_random_state *rrsp)
 330 {
 331         if (--rrsp->rrs_count < 0) {
 332                 rrsp->rrs_state += (unsigned long)local_clock();
 333                 rrsp->rrs_count = RCU_RANDOM_REFRESH;
 334         }
 335         rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
 336         return swahw32(rrsp->rrs_state);
 337 }
 338
 339 static void
 340 rcu_stutter_wait(char *title)
 341 {
 342         while (stutter_pause_test || !rcutorture_runnable) {
 343                 if (rcutorture_runnable)
 344                         schedule_timeout_interruptible(1);
 345                 else
 346                         schedule_timeout_interruptible(round_jiffies_relative(HZ));
 347                 rcutorture_shutdown_absorb(title);
 348         }
 349 }
 350
 351 /*
 352  * Operations vector for selecting different types of tests.
 353  */
 354
 355 struct rcu_torture_ops {
 356         void (*init)(void);
 357         int (*readlock)(void);
 358         void (*read_delay)(struct rcu_random_state *rrsp);
 359         void (*readunlock)(int idx);
 360         int (*completed)(void);
 361         void (*deferred_free)(struct rcu_torture *p);
 362         void (*sync)(void);
 363         void (*call)(struct rcu_head *head, void (*func)(struct rcu_head *rcu));
 364         void (*cb_barrier)(void);
 365         void (*fqs)(void);
 366         int (*stats)(char *page);
 367         int irq_capable;
 368         int can_boost;
 369         char *name;
 370 };
 371
 372 static struct rcu_torture_ops *cur_ops;
 373
 374 /*
 375  * Definitions for rcu torture testing.
 376  */
 377
 378 static int rcu_torture_read_lock(void) __acquires(RCU)
 379 {
 380         rcu_read_lock();
 381         return 0;
 382 }
 383
 384 static void rcu_read_delay(struct rcu_random_state *rrsp)
 385 {
 386         const unsigned long shortdelay_us = 200;
 387         const unsigned long longdelay_ms = 50;
 388
 389         /* We want a short delay sometimes to make a reader delay the grace
 390          * period, and we want a long delay occasionally to trigger
 391          * force_quiescent_state. */
 392
 393         if (!(rcu_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
 394                 mdelay(longdelay_ms);
 395         if (!(rcu_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
 396                 udelay(shortdelay_us);
 397 #ifdef CONFIG_PREEMPT
 398         if (!preempt_count() && !(rcu_random(rrsp) % (nrealreaders * 20000)))
 399                 preempt_schedule();  /* No QS if preempt_disable() in effect */
 400 #endif
 401 }
 402
 403 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 404 {
 405         rcu_read_unlock();
 406 }
 407
 408 static int rcu_torture_completed(void)
 409 {
 410         return rcu_batches_completed();
 411 }
 412
 413 static void
 414 rcu_torture_cb(struct rcu_head *p)
 415 {
 416         int i;
 417         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 418
 419         if (fullstop != FULLSTOP_DONTSTOP) {
 420                 /* Test is ending, just drop callbacks on the floor. */
 421                 /* The next initialization will pick up the pieces. */
 422                 return;
 423         }
 424         i = rp->rtort_pipe_count;
 425         if (i > RCU_TORTURE_PIPE_LEN)
 426                 i = RCU_TORTURE_PIPE_LEN;
 427         atomic_inc(&rcu_torture_wcount[i]);
 428         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 429                 rp->rtort_mbtest = 0;
 430                 rcu_torture_free(rp);
 431         } else {
 432                 cur_ops->deferred_free(rp);
 433         }
 434 }
 435
 436 static int rcu_no_completed(void)
 437 {
 438         return 0;
 439 }
 440
 441 static void rcu_torture_deferred_free(struct rcu_torture *p)
 442 {
 443         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 444 }
 445
 446 static struct rcu_torture_ops rcu_ops = {
 447         .init           = NULL,
 448         .readlock       = rcu_torture_read_lock,
 449         .read_delay     = rcu_read_delay,
 450         .readunlock     = rcu_torture_read_unlock,
 451         .completed      = rcu_torture_completed,
 452         .deferred_free  = rcu_torture_deferred_free,
 453         .sync           = synchronize_rcu,
 454         .call           = call_rcu,
 455         .cb_barrier     = rcu_barrier,
 456         .fqs            = rcu_force_quiescent_state,
 457         .stats          = NULL,
 458         .irq_capable    = 1,
 459         .can_boost      = rcu_can_boost(),
 460         .name           = "rcu"
 461 };
 462
 463 static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
 464 {
 465         int i;
 466         struct rcu_torture *rp;
 467         struct rcu_torture *rp1;
 468
 469         cur_ops->sync();
 470         list_add(&p->rtort_free, &rcu_torture_removed);
 471         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 472                 i = rp->rtort_pipe_count;
 473                 if (i > RCU_TORTURE_PIPE_LEN)
 474                         i = RCU_TORTURE_PIPE_LEN;
 475                 atomic_inc(&rcu_torture_wcount[i]);
 476                 if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 477                         rp->rtort_mbtest = 0;
 478                         list_del(&rp->rtort_free);
 479                         rcu_torture_free(rp);
 480                 }
 481         }
 482 }
 483
 484 static void rcu_sync_torture_init(void)
 485 {
 486         INIT_LIST_HEAD(&rcu_torture_removed);
 487 }
 488
 489 static struct rcu_torture_ops rcu_sync_ops = {
 490         .init           = rcu_sync_torture_init,
 491         .readlock       = rcu_torture_read_lock,
 492         .read_delay     = rcu_read_delay,
 493         .readunlock     = rcu_torture_read_unlock,
 494         .completed      = rcu_torture_completed,
 495         .deferred_free  = rcu_sync_torture_deferred_free,
 496         .sync           = synchronize_rcu,
 497         .call           = NULL,
 498         .cb_barrier     = NULL,
 499         .fqs            = rcu_force_quiescent_state,
 500         .stats          = NULL,
 501         .irq_capable    = 1,
 502         .can_boost      = rcu_can_boost(),
 503         .name           = "rcu_sync"
 504 };
 505
 506 static struct rcu_torture_ops rcu_expedited_ops = {
 507         .init           = rcu_sync_torture_init,
 508         .readlock       = rcu_torture_read_lock,
 509         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 510         .readunlock     = rcu_torture_read_unlock,
 511         .completed      = rcu_no_completed,
 512         .deferred_free  = rcu_sync_torture_deferred_free,
 513         .sync           = synchronize_rcu_expedited,
 514         .call           = NULL,
 515         .cb_barrier     = NULL,
 516         .fqs            = rcu_force_quiescent_state,
 517         .stats          = NULL,
 518         .irq_capable    = 1,
 519         .can_boost      = rcu_can_boost(),
 520         .name           = "rcu_expedited"
 521 };
 522
 523 /*
 524  * Definitions for rcu_bh torture testing.
 525  */
 526
 527 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
 528 {
 529         rcu_read_lock_bh();
 530         return 0;
 531 }
 532
 533 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
 534 {
 535         rcu_read_unlock_bh();
 536 }
 537
 538 static int rcu_bh_torture_completed(void)
 539 {
 540         return rcu_batches_completed_bh();
 541 }
 542
 543 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 544 {
 545         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
 546 }
 547
 548 static struct rcu_torture_ops rcu_bh_ops = {
 549         .init           = NULL,
 550         .readlock       = rcu_bh_torture_read_lock,
 551         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 552         .readunlock     = rcu_bh_torture_read_unlock,
 553         .completed      = rcu_bh_torture_completed,
 554         .deferred_free  = rcu_bh_torture_deferred_free,
 555         .sync           = synchronize_rcu_bh,
 556         .call           = call_rcu_bh,
 557         .cb_barrier     = rcu_barrier_bh,
 558         .fqs            = rcu_bh_force_quiescent_state,
 559         .stats          = NULL,
 560         .irq_capable    = 1,
 561         .name           = "rcu_bh"
 562 };
 563
 564 static struct rcu_torture_ops rcu_bh_sync_ops = {
 565         .init           = rcu_sync_torture_init,
 566         .readlock       = rcu_bh_torture_read_lock,
 567         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 568         .readunlock     = rcu_bh_torture_read_unlock,
 569         .completed      = rcu_bh_torture_completed,
 570         .deferred_free  = rcu_sync_torture_deferred_free,
 571         .sync           = synchronize_rcu_bh,
 572         .call           = NULL,
 573         .cb_barrier     = NULL,
 574         .fqs            = rcu_bh_force_quiescent_state,
 575         .stats          = NULL,
 576         .irq_capable    = 1,
 577         .name           = "rcu_bh_sync"
 578 };
 579
 580 static struct rcu_torture_ops rcu_bh_expedited_ops = {
 581         .init           = rcu_sync_torture_init,
 582         .readlock       = rcu_bh_torture_read_lock,
 583         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 584         .readunlock     = rcu_bh_torture_read_unlock,
 585         .completed      = rcu_bh_torture_completed,
 586         .deferred_free  = rcu_sync_torture_deferred_free,
 587         .sync           = synchronize_rcu_bh_expedited,
 588         .call           = NULL,
 589         .cb_barrier     = NULL,
 590         .fqs            = rcu_bh_force_quiescent_state,
 591         .stats          = NULL,
 592         .irq_capable    = 1,
 593         .name           = "rcu_bh_expedited"
 594 };
 595
 596 /*
 597  * Definitions for srcu torture testing.
 598  */
 599
 600 DEFINE_STATIC_SRCU(srcu_ctl);
 601
 602 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
 603 {
 604         return srcu_read_lock(&srcu_ctl);
 605 }
 606
 607 static void srcu_read_delay(struct rcu_random_state *rrsp)
 608 {
 609         long delay;
 610         const long uspertick = 1000000 / HZ;
 611         const long longdelay = 10;
 612
 613         /* We want there to be long-running readers, but not all the time. */
 614
 615         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
 616         if (!delay)
 617                 schedule_timeout_interruptible(longdelay);
 618         else
 619                 rcu_read_delay(rrsp);
 620 }
 621
 622 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
 623 {
 624         srcu_read_unlock(&srcu_ctl, idx);
 625 }
 626
 627 static int srcu_torture_completed(void)
 628 {
 629         return srcu_batches_completed(&srcu_ctl);
 630 }
 631
 632 static void srcu_torture_deferred_free(struct rcu_torture *rp)
 633 {
 634         call_srcu(&srcu_ctl, &rp->rtort_rcu, rcu_torture_cb);
 635 }
 636
 637 static void srcu_torture_synchronize(void)
 638 {
 639         synchronize_srcu(&srcu_ctl);
 640 }
 641
 642 static void srcu_torture_call(struct rcu_head *head,
 643                               void (*func)(struct rcu_head *head))
 644 {
 645         call_srcu(&srcu_ctl, head, func);
 646 }
 647
 648 static void srcu_torture_barrier(void)
 649 {
 650         srcu_barrier(&srcu_ctl);
 651 }
 652
 653 static int srcu_torture_stats(char *page)
 654 {
 655         int cnt = 0;
 656         int cpu;
 657         int idx = srcu_ctl.completed & 0x1;
 658
 659         cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
 660                        torture_type, TORTURE_FLAG, idx);
 661         for_each_possible_cpu(cpu) {
 662                 cnt += sprintf(&page[cnt], " %d(%lu,%lu)", cpu,
 663                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
 664                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
 665         }
 666         cnt += sprintf(&page[cnt], "\n");
 667         return cnt;
 668 }
 669
 670 static struct rcu_torture_ops srcu_ops = {
 671         .init           = rcu_sync_torture_init,
 672         .readlock       = srcu_torture_read_lock,
 673         .read_delay     = srcu_read_delay,
 674         .readunlock     = srcu_torture_read_unlock,
 675         .completed      = srcu_torture_completed,
 676         .deferred_free  = srcu_torture_deferred_free,
 677         .sync           = srcu_torture_synchronize,
 678         .call           = srcu_torture_call,
 679         .cb_barrier     = srcu_torture_barrier,
 680         .stats          = srcu_torture_stats,
 681         .name           = "srcu"
 682 };
 683
 684 static struct rcu_torture_ops srcu_sync_ops = {
 685         .init           = rcu_sync_torture_init,
 686         .readlock       = srcu_torture_read_lock,
 687         .read_delay     = srcu_read_delay,
 688         .readunlock     = srcu_torture_read_unlock,
 689         .completed      = srcu_torture_completed,
 690         .deferred_free  = rcu_sync_torture_deferred_free,
 691         .sync           = srcu_torture_synchronize,
 692         .call           = NULL,
 693         .cb_barrier     = NULL,
 694         .stats          = srcu_torture_stats,
 695         .name           = "srcu_sync"
 696 };
 697
 698 static int srcu_torture_read_lock_raw(void) __acquires(&srcu_ctl)
 699 {
 700         return srcu_read_lock_raw(&srcu_ctl);
 701 }
 702
 703 static void srcu_torture_read_unlock_raw(int idx) __releases(&srcu_ctl)
 704 {
 705         srcu_read_unlock_raw(&srcu_ctl, idx);
 706 }
 707
 708 static struct rcu_torture_ops srcu_raw_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  = srcu_torture_deferred_free,
 715         .sync           = srcu_torture_synchronize,
 716         .call           = NULL,
 717         .cb_barrier     = NULL,
 718         .stats          = srcu_torture_stats,
 719         .name           = "srcu_raw"
 720 };
 721
 722 static struct rcu_torture_ops srcu_raw_sync_ops = {
 723         .init           = rcu_sync_torture_init,
 724         .readlock       = srcu_torture_read_lock_raw,
 725         .read_delay     = srcu_read_delay,
 726         .readunlock     = srcu_torture_read_unlock_raw,
 727         .completed      = srcu_torture_completed,
 728         .deferred_free  = rcu_sync_torture_deferred_free,
 729         .sync           = srcu_torture_synchronize,
 730         .call           = NULL,
 731         .cb_barrier     = NULL,
 732         .stats          = srcu_torture_stats,
 733         .name           = "srcu_raw_sync"
 734 };
 735
 736 static void srcu_torture_synchronize_expedited(void)
 737 {
 738         synchronize_srcu_expedited(&srcu_ctl);
 739 }
 740
 741 static struct rcu_torture_ops srcu_expedited_ops = {
 742         .init           = rcu_sync_torture_init,
 743         .readlock       = srcu_torture_read_lock,
 744         .read_delay     = srcu_read_delay,
 745         .readunlock     = srcu_torture_read_unlock,
 746         .completed      = srcu_torture_completed,
 747         .deferred_free  = rcu_sync_torture_deferred_free,
 748         .sync           = srcu_torture_synchronize_expedited,
 749         .call           = NULL,
 750         .cb_barrier     = NULL,
 751         .stats          = srcu_torture_stats,
 752         .name           = "srcu_expedited"
 753 };
 754
 755 /*
 756  * Definitions for sched torture testing.
 757  */
 758
 759 static int sched_torture_read_lock(void)
 760 {
 761         preempt_disable();
 762         return 0;
 763 }
 764
 765 static void sched_torture_read_unlock(int idx)
 766 {
 767         preempt_enable();
 768 }
 769
 770 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
 771 {
 772         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
 773 }
 774
 775 static struct rcu_torture_ops sched_ops = {
 776         .init           = rcu_sync_torture_init,
 777         .readlock       = sched_torture_read_lock,
 778         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 779         .readunlock     = sched_torture_read_unlock,
 780         .completed      = rcu_no_completed,
 781         .deferred_free  = rcu_sched_torture_deferred_free,
 782         .sync           = synchronize_sched,
 783         .cb_barrier     = rcu_barrier_sched,
 784         .fqs            = rcu_sched_force_quiescent_state,
 785         .stats          = NULL,
 786         .irq_capable    = 1,
 787         .name           = "sched"
 788 };
 789
 790 static struct rcu_torture_ops sched_sync_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,
 798         .cb_barrier     = NULL,
 799         .fqs            = rcu_sched_force_quiescent_state,
 800         .stats          = NULL,
 801         .name           = "sched_sync"
 802 };
 803
 804 static struct rcu_torture_ops sched_expedited_ops = {
 805         .init           = rcu_sync_torture_init,
 806         .readlock       = sched_torture_read_lock,
 807         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 808         .readunlock     = sched_torture_read_unlock,
 809         .completed      = rcu_no_completed,
 810         .deferred_free  = rcu_sync_torture_deferred_free,
 811         .sync           = synchronize_sched_expedited,
 812         .cb_barrier     = NULL,
 813         .fqs            = rcu_sched_force_quiescent_state,
 814         .stats          = NULL,
 815         .irq_capable    = 1,
 816         .name           = "sched_expedited"
 817 };
 818
 819 /*
 820  * RCU torture priority-boost testing.  Runs one real-time thread per
 821  * CPU for moderate bursts, repeatedly registering RCU callbacks and
 822  * spinning waiting for them to be invoked.  If a given callback takes
 823  * too long to be invoked, we assume that priority inversion has occurred.
 824  */
 825
 826 struct rcu_boost_inflight {
 827         struct rcu_head rcu;
 828         int inflight;
 829 };
 830
 831 static void rcu_torture_boost_cb(struct rcu_head *head)
 832 {
 833         struct rcu_boost_inflight *rbip =
 834                 container_of(head, struct rcu_boost_inflight, rcu);
 835
 836         smp_mb(); /* Ensure RCU-core accesses precede clearing ->inflight */
 837         rbip->inflight = 0;
 838 }
 839
 840 static int rcu_torture_boost(void *arg)
 841 {
 842         unsigned long call_rcu_time;
 843         unsigned long endtime;
 844         unsigned long oldstarttime;
 845         struct rcu_boost_inflight rbi = { .inflight = 0 };
 846         struct sched_param sp;
 847
 848         VERBOSE_PRINTK_STRING("rcu_torture_boost started");
 849
 850         /* Set real-time priority. */
 851         sp.sched_priority = 1;
 852         if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 853                 VERBOSE_PRINTK_STRING("rcu_torture_boost RT prio failed!");
 854                 n_rcu_torture_boost_rterror++;
 855         }
 856
 857         init_rcu_head_on_stack(&rbi.rcu);
 858         /* Each pass through the following loop does one boost-test cycle. */
 859         do {
 860                 /* Wait for the next test interval. */
 861                 oldstarttime = boost_starttime;
 862                 while (ULONG_CMP_LT(jiffies, oldstarttime)) {
 863                         schedule_timeout_interruptible(oldstarttime - jiffies);
 864                         rcu_stutter_wait("rcu_torture_boost");
 865                         if (kthread_should_stop() ||
 866                             fullstop != FULLSTOP_DONTSTOP)
 867                                 goto checkwait;
 868                 }
 869
 870                 /* Do one boost-test interval. */
 871                 endtime = oldstarttime + test_boost_duration * HZ;
 872                 call_rcu_time = jiffies;
 873                 while (ULONG_CMP_LT(jiffies, endtime)) {
 874                         /* If we don't have a callback in flight, post one. */
 875                         if (!rbi.inflight) {
 876                                 smp_mb(); /* RCU core before ->inflight = 1. */
 877                                 rbi.inflight = 1;
 878                                 call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 879                                 if (jiffies - call_rcu_time >
 880                                          test_boost_duration * HZ - HZ / 2) {
 881                                         VERBOSE_PRINTK_STRING("rcu_torture_boost boosting failed");
 882                                         n_rcu_torture_boost_failure++;
 883                                 }
 884                                 call_rcu_time = jiffies;
 885                         }
 886                         cond_resched();
 887                         rcu_stutter_wait("rcu_torture_boost");
 888                         if (kthread_should_stop() ||
 889                             fullstop != FULLSTOP_DONTSTOP)
 890                                 goto checkwait;
 891                 }
 892
 893                 /*
 894                  * Set the start time of the next test interval.
 895                  * Yes, this is vulnerable to long delays, but such
 896                  * delays simply cause a false negative for the next
 897                  * interval.  Besides, we are running at RT priority,
 898                  * so delays should be relatively rare.
 899                  */
 900                 while (oldstarttime == boost_starttime &&
 901                        !kthread_should_stop()) {
 902                         if (mutex_trylock(&boost_mutex)) {
 903                                 boost_starttime = jiffies +
 904                                                   test_boost_interval * HZ;
 905                                 n_rcu_torture_boosts++;
 906                                 mutex_unlock(&boost_mutex);
 907                                 break;
 908                         }
 909                         schedule_timeout_uninterruptible(1);
 910                 }
 911
 912                 /* Go do the stutter. */
 913 checkwait:      rcu_stutter_wait("rcu_torture_boost");
 914         } while (!kthread_should_stop() && fullstop  == FULLSTOP_DONTSTOP);
 915
 916         /* Clean up and exit. */
 917         VERBOSE_PRINTK_STRING("rcu_torture_boost task stopping");
 918         rcutorture_shutdown_absorb("rcu_torture_boost");
 919         while (!kthread_should_stop() || rbi.inflight)
 920                 schedule_timeout_uninterruptible(1);
 921         smp_mb(); /* order accesses to ->inflight before stack-frame death. */
 922         destroy_rcu_head_on_stack(&rbi.rcu);
 923         return 0;
 924 }
 925
 926 /*
 927  * RCU torture force-quiescent-state kthread.  Repeatedly induces
 928  * bursts of calls to force_quiescent_state(), increasing the probability
 929  * of occurrence of some important types of race conditions.
 930  */
 931 static int
 932 rcu_torture_fqs(void *arg)
 933 {
 934         unsigned long fqs_resume_time;
 935         int fqs_burst_remaining;
 936
 937         VERBOSE_PRINTK_STRING("rcu_torture_fqs task started");
 938         do {
 939                 fqs_resume_time = jiffies + fqs_stutter * HZ;
 940                 while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
 941                        !kthread_should_stop()) {
 942                         schedule_timeout_interruptible(1);
 943                 }
 944                 fqs_burst_remaining = fqs_duration;
 945                 while (fqs_burst_remaining > 0 &&
 946                        !kthread_should_stop()) {
 947                         cur_ops->fqs();
 948                         udelay(fqs_holdoff);
 949                         fqs_burst_remaining -= fqs_holdoff;
 950                 }
 951                 rcu_stutter_wait("rcu_torture_fqs");
 952         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 953         VERBOSE_PRINTK_STRING("rcu_torture_fqs task stopping");
 954         rcutorture_shutdown_absorb("rcu_torture_fqs");
 955         while (!kthread_should_stop())
 956                 schedule_timeout_uninterruptible(1);
 957         return 0;
 958 }
 959
 960 /*
 961  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 962  * for that pointed to by rcu_torture_current, freeing the old structure
 963  * after a series of grace periods (the "pipeline").
 964  */
 965 static int
 966 rcu_torture_writer(void *arg)
 967 {
 968         int i;
 969         long oldbatch = rcu_batches_completed();
 970         struct rcu_torture *rp;
 971         struct rcu_torture *old_rp;
 972         static DEFINE_RCU_RANDOM(rand);
 973
 974         VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
 975         set_user_nice(current, 19);
 976
 977         do {
 978                 schedule_timeout_uninterruptible(1);
 979                 rp = rcu_torture_alloc();
 980                 if (rp == NULL)
 981                         continue;
 982                 rp->rtort_pipe_count = 0;
 983                 udelay(rcu_random(&rand) & 0x3ff);
 984                 old_rp = rcu_dereference_check(rcu_torture_current,
 985                                                current == writer_task);
 986                 rp->rtort_mbtest = 1;
 987                 rcu_assign_pointer(rcu_torture_current, rp);
 988                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
 989                 if (old_rp) {
 990                         i = old_rp->rtort_pipe_count;
 991                         if (i > RCU_TORTURE_PIPE_LEN)
 992                                 i = RCU_TORTURE_PIPE_LEN;
 993                         atomic_inc(&rcu_torture_wcount[i]);
 994                         old_rp->rtort_pipe_count++;
 995                         cur_ops->deferred_free(old_rp);
 996                 }
 997                 rcutorture_record_progress(++rcu_torture_current_version);
 998                 oldbatch = cur_ops->completed();
 999                 rcu_stutter_wait("rcu_torture_writer");
1000         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1001         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
1002         rcutorture_shutdown_absorb("rcu_torture_writer");
1003         while (!kthread_should_stop())
1004                 schedule_timeout_uninterruptible(1);
1005         return 0;
1006 }
1007
1008 /*
1009  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
1010  * delay between calls.
1011  */
1012 static int
1013 rcu_torture_fakewriter(void *arg)
1014 {
1015         DEFINE_RCU_RANDOM(rand);
1016
1017         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
1018         set_user_nice(current, 19);
1019
1020         do {
1021                 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
1022                 udelay(rcu_random(&rand) & 0x3ff);
1023                 if (cur_ops->cb_barrier != NULL &&
1024                     rcu_random(&rand) % (nfakewriters * 8) == 0)
1025                         cur_ops->cb_barrier();
1026                 else
1027                         cur_ops->sync();
1028                 rcu_stutter_wait("rcu_torture_fakewriter");
1029         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1030
1031         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
1032         rcutorture_shutdown_absorb("rcu_torture_fakewriter");
1033         while (!kthread_should_stop())
1034                 schedule_timeout_uninterruptible(1);
1035         return 0;
1036 }
1037
1038 void rcutorture_trace_dump(void)
1039 {
1040         static atomic_t beenhere = ATOMIC_INIT(0);
1041
1042         if (atomic_read(&beenhere))
1043                 return;
1044         if (atomic_xchg(&beenhere, 1) != 0)
1045                 return;
1046         ftrace_dump(DUMP_ALL);
1047 }
1048
1049 /*
1050  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
1051  * incrementing the corresponding element of the pipeline array.  The
1052  * counter in the element should never be greater than 1, otherwise, the
1053  * RCU implementation is broken.
1054  */
1055 static void rcu_torture_timer(unsigned long unused)
1056 {
1057         int idx;
1058         int completed;
1059         int completed_end;
1060         static DEFINE_RCU_RANDOM(rand);
1061         static DEFINE_SPINLOCK(rand_lock);
1062         struct rcu_torture *p;
1063         int pipe_count;
1064         unsigned long long ts;
1065
1066         idx = cur_ops->readlock();
1067         completed = cur_ops->completed();
1068         ts = rcu_trace_clock_local();
1069         p = rcu_dereference_check(rcu_torture_current,
1070                                   rcu_read_lock_bh_held() ||
1071                                   rcu_read_lock_sched_held() ||
1072                                   srcu_read_lock_held(&srcu_ctl));
1073         if (p == NULL) {
1074                 /* Leave because rcu_torture_writer is not yet underway */
1075                 cur_ops->readunlock(idx);
1076                 return;
1077         }
1078         if (p->rtort_mbtest == 0)
1079                 atomic_inc(&n_rcu_torture_mberror);
1080         spin_lock(&rand_lock);
1081         cur_ops->read_delay(&rand);
1082         n_rcu_torture_timers++;
1083         spin_unlock(&rand_lock);
1084         preempt_disable();
1085         pipe_count = p->rtort_pipe_count;
1086         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1087                 /* Should not happen, but... */
1088                 pipe_count = RCU_TORTURE_PIPE_LEN;
1089         }
1090         completed_end = cur_ops->completed();
1091         if (pipe_count > 1) {
1092                 do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu, ts,
1093                                           completed, completed_end);
1094                 rcutorture_trace_dump();
1095         }
1096         __this_cpu_inc(rcu_torture_count[pipe_count]);
1097         completed = completed_end - completed;
1098         if (completed > RCU_TORTURE_PIPE_LEN) {
1099                 /* Should not happen, but... */
1100                 completed = RCU_TORTURE_PIPE_LEN;
1101         }
1102         __this_cpu_inc(rcu_torture_batch[completed]);
1103         preempt_enable();
1104         cur_ops->readunlock(idx);
1105 }
1106
1107 /*
1108  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
1109  * incrementing the corresponding element of the pipeline array.  The
1110  * counter in the element should never be greater than 1, otherwise, the
1111  * RCU implementation is broken.
1112  */
1113 static int
1114 rcu_torture_reader(void *arg)
1115 {
1116         int completed;
1117         int completed_end;
1118         int idx;
1119         DEFINE_RCU_RANDOM(rand);
1120         struct rcu_torture *p;
1121         int pipe_count;
1122         struct timer_list t;
1123         unsigned long long ts;
1124
1125         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
1126         set_user_nice(current, 19);
1127         if (irqreader && cur_ops->irq_capable)
1128                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
1129
1130         do {
1131                 if (irqreader && cur_ops->irq_capable) {
1132                         if (!timer_pending(&t))
1133                                 mod_timer(&t, jiffies + 1);
1134                 }
1135                 idx = cur_ops->readlock();
1136                 completed = cur_ops->completed();
1137                 ts = rcu_trace_clock_local();
1138                 p = rcu_dereference_check(rcu_torture_current,
1139                                           rcu_read_lock_bh_held() ||
1140                                           rcu_read_lock_sched_held() ||
1141                                           srcu_read_lock_held(&srcu_ctl));
1142                 if (p == NULL) {
1143                         /* Wait for rcu_torture_writer to get underway */
1144                         cur_ops->readunlock(idx);
1145                         schedule_timeout_interruptible(HZ);
1146                         continue;
1147                 }
1148                 if (p->rtort_mbtest == 0)
1149                         atomic_inc(&n_rcu_torture_mberror);
1150                 cur_ops->read_delay(&rand);
1151                 preempt_disable();
1152                 pipe_count = p->rtort_pipe_count;
1153                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1154                         /* Should not happen, but... */
1155                         pipe_count = RCU_TORTURE_PIPE_LEN;
1156                 }
1157                 completed_end = cur_ops->completed();
1158                 if (pipe_count > 1) {
1159                         do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
1160                                                   ts, completed, completed_end);
1161                         rcutorture_trace_dump();
1162                 }
1163                 __this_cpu_inc(rcu_torture_count[pipe_count]);
1164                 completed = completed_end - completed;
1165                 if (completed > RCU_TORTURE_PIPE_LEN) {
1166                         /* Should not happen, but... */
1167                         completed = RCU_TORTURE_PIPE_LEN;
1168                 }
1169                 __this_cpu_inc(rcu_torture_batch[completed]);
1170                 preempt_enable();
1171                 cur_ops->readunlock(idx);
1172                 schedule();
1173                 rcu_stutter_wait("rcu_torture_reader");
1174         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1175         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
1176         rcutorture_shutdown_absorb("rcu_torture_reader");
1177         if (irqreader && cur_ops->irq_capable)
1178                 del_timer_sync(&t);
1179         while (!kthread_should_stop())
1180                 schedule_timeout_uninterruptible(1);
1181         return 0;
1182 }
1183
1184 /*
1185  * Create an RCU-torture statistics message in the specified buffer.
1186  */
1187 static int
1188 rcu_torture_printk(char *page)
1189 {
1190         int cnt = 0;
1191         int cpu;
1192         int i;
1193         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1194         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1195
1196         for_each_possible_cpu(cpu) {
1197                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1198                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1199                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1200                 }
1201         }
1202         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1203                 if (pipesummary[i] != 0)
1204                         break;
1205         }
1206         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
1207         cnt += sprintf(&page[cnt],
1208                        "rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
1209                        rcu_torture_current,
1210                        rcu_torture_current_version,
1211                        list_empty(&rcu_torture_freelist),
1212                        atomic_read(&n_rcu_torture_alloc),
1213                        atomic_read(&n_rcu_torture_alloc_fail),
1214                        atomic_read(&n_rcu_torture_free));
1215         cnt += sprintf(&page[cnt], "rtmbe: %d rtbke: %ld rtbre: %ld ",
1216                        atomic_read(&n_rcu_torture_mberror),
1217                        n_rcu_torture_boost_ktrerror,
1218                        n_rcu_torture_boost_rterror);
1219         cnt += sprintf(&page[cnt], "rtbf: %ld rtb: %ld nt: %ld ",
1220                        n_rcu_torture_boost_failure,
1221                        n_rcu_torture_boosts,
1222                        n_rcu_torture_timers);
1223         cnt += sprintf(&page[cnt],
1224                        "onoff: %ld/%ld:%ld/%ld %d,%d:%d,%d %lu:%lu (HZ=%d) ",
1225                        n_online_successes, n_online_attempts,
1226                        n_offline_successes, n_offline_attempts,
1227                        min_online, max_online,
1228                        min_offline, max_offline,
1229                        sum_online, sum_offline, HZ);
1230         cnt += sprintf(&page[cnt], "barrier: %ld/%ld:%ld",
1231                        n_barrier_successes,
1232                        n_barrier_attempts,
1233                        n_rcu_torture_barrier_error);
1234         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1235         if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1236             n_rcu_torture_barrier_error != 0 ||
1237             n_rcu_torture_boost_ktrerror != 0 ||
1238             n_rcu_torture_boost_rterror != 0 ||
1239             n_rcu_torture_boost_failure != 0 ||
1240             i > 1) {
1241                 cnt += sprintf(&page[cnt], "!!! ");
1242                 atomic_inc(&n_rcu_torture_error);
1243                 WARN_ON_ONCE(1);
1244         }
1245         cnt += sprintf(&page[cnt], "Reader Pipe: ");
1246         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1247                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
1248         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1249         cnt += sprintf(&page[cnt], "Reader Batch: ");
1250         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1251                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
1252         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1253         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
1254         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1255                 cnt += sprintf(&page[cnt], " %d",
1256                                atomic_read(&rcu_torture_wcount[i]));
1257         }
1258         cnt += sprintf(&page[cnt], "\n");
1259         if (cur_ops->stats)
1260                 cnt += cur_ops->stats(&page[cnt]);
1261         return cnt;
1262 }
1263
1264 /*
1265  * Print torture statistics.  Caller must ensure that there is only
1266  * one call to this function at a given time!!!  This is normally
1267  * accomplished by relying on the module system to only have one copy
1268  * of the module loaded, and then by giving the rcu_torture_stats
1269  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1270  * thread is not running).
1271  */
1272 static void
1273 rcu_torture_stats_print(void)
1274 {
1275         int cnt;
1276
1277         cnt = rcu_torture_printk(printk_buf);
1278         pr_alert("%s", printk_buf);
1279 }
1280
1281 /*
1282  * Periodically prints torture statistics, if periodic statistics printing
1283  * was specified via the stat_interval module parameter.
1284  *
1285  * No need to worry about fullstop here, since this one doesn't reference
1286  * volatile state or register callbacks.
1287  */
1288 static int
1289 rcu_torture_stats(void *arg)
1290 {
1291         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
1292         do {
1293                 schedule_timeout_interruptible(stat_interval * HZ);
1294                 rcu_torture_stats_print();
1295                 rcutorture_shutdown_absorb("rcu_torture_stats");
1296         } while (!kthread_should_stop());
1297         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
1298         return 0;
1299 }
1300
1301 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
1302
1303 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
1304  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
1305  */
1306 static void rcu_torture_shuffle_tasks(void)
1307 {
1308         int i;
1309
1310         cpumask_setall(shuffle_tmp_mask);
1311         get_online_cpus();
1312
1313         /* No point in shuffling if there is only one online CPU (ex: UP) */
1314         if (num_online_cpus() == 1) {
1315                 put_online_cpus();
1316                 return;
1317         }
1318
1319         if (rcu_idle_cpu != -1)
1320                 cpumask_clear_cpu(rcu_idle_cpu, shuffle_tmp_mask);
1321
1322         set_cpus_allowed_ptr(current, shuffle_tmp_mask);
1323
1324         if (reader_tasks) {
1325                 for (i = 0; i < nrealreaders; i++)
1326                         if (reader_tasks[i])
1327                                 set_cpus_allowed_ptr(reader_tasks[i],
1328                                                      shuffle_tmp_mask);
1329         }
1330         if (fakewriter_tasks) {
1331                 for (i = 0; i < nfakewriters; i++)
1332                         if (fakewriter_tasks[i])
1333                                 set_cpus_allowed_ptr(fakewriter_tasks[i],
1334                                                      shuffle_tmp_mask);
1335         }
1336         if (writer_task)
1337                 set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
1338         if (stats_task)
1339                 set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
1340         if (stutter_task)
1341                 set_cpus_allowed_ptr(stutter_task, shuffle_tmp_mask);
1342         if (fqs_task)
1343                 set_cpus_allowed_ptr(fqs_task, shuffle_tmp_mask);
1344         if (shutdown_task)
1345                 set_cpus_allowed_ptr(shutdown_task, shuffle_tmp_mask);
1346 #ifdef CONFIG_HOTPLUG_CPU
1347         if (onoff_task)
1348                 set_cpus_allowed_ptr(onoff_task, shuffle_tmp_mask);
1349 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
1350         if (stall_task)
1351                 set_cpus_allowed_ptr(stall_task, shuffle_tmp_mask);
1352         if (barrier_cbs_tasks)
1353                 for (i = 0; i < n_barrier_cbs; i++)
1354                         if (barrier_cbs_tasks[i])
1355                                 set_cpus_allowed_ptr(barrier_cbs_tasks[i],
1356                                                      shuffle_tmp_mask);
1357         if (barrier_task)
1358                 set_cpus_allowed_ptr(barrier_task, shuffle_tmp_mask);
1359
1360         if (rcu_idle_cpu == -1)
1361                 rcu_idle_cpu = num_online_cpus() - 1;
1362         else
1363                 rcu_idle_cpu--;
1364
1365         put_online_cpus();
1366 }
1367
1368 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
1369  * system to become idle at a time and cut off its timer ticks. This is meant
1370  * to test the support for such tickless idle CPU in RCU.
1371  */
1372 static int
1373 rcu_torture_shuffle(void *arg)
1374 {
1375         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
1376         do {
1377                 schedule_timeout_interruptible(shuffle_interval * HZ);
1378                 rcu_torture_shuffle_tasks();
1379                 rcutorture_shutdown_absorb("rcu_torture_shuffle");
1380         } while (!kthread_should_stop());
1381         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
1382         return 0;
1383 }
1384
1385 /* Cause the rcutorture test to "stutter", starting and stopping all
1386  * threads periodically.
1387  */
1388 static int
1389 rcu_torture_stutter(void *arg)
1390 {
1391         VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
1392         do {
1393                 schedule_timeout_interruptible(stutter * HZ);
1394                 stutter_pause_test = 1;
1395                 if (!kthread_should_stop())
1396                         schedule_timeout_interruptible(stutter * HZ);
1397                 stutter_pause_test = 0;
1398                 rcutorture_shutdown_absorb("rcu_torture_stutter");
1399         } while (!kthread_should_stop());
1400         VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
1401         return 0;
1402 }
1403
1404 static inline void
1405 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, char *tag)
1406 {
1407         pr_alert("%s" TORTURE_FLAG
1408                  "--- %s: nreaders=%d nfakewriters=%d "
1409                  "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1410                  "shuffle_interval=%d stutter=%d irqreader=%d "
1411                  "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1412                  "test_boost=%d/%d test_boost_interval=%d "
1413                  "test_boost_duration=%d shutdown_secs=%d "
1414                  "stall_cpu=%d stall_cpu_holdoff=%d "
1415                  "n_barrier_cbs=%d "
1416                  "onoff_interval=%d onoff_holdoff=%d\n",
1417                  torture_type, tag, nrealreaders, nfakewriters,
1418                  stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1419                  stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1420                  test_boost, cur_ops->can_boost,
1421                  test_boost_interval, test_boost_duration, shutdown_secs,
1422                  stall_cpu, stall_cpu_holdoff,
1423                  n_barrier_cbs,
1424                  onoff_interval, onoff_holdoff);
1425 }
1426
1427 static struct notifier_block rcutorture_shutdown_nb = {
1428         .notifier_call = rcutorture_shutdown_notify,
1429 };
1430
1431 static void rcutorture_booster_cleanup(int cpu)
1432 {
1433         struct task_struct *t;
1434
1435         if (boost_tasks[cpu] == NULL)
1436                 return;
1437         mutex_lock(&boost_mutex);
1438         VERBOSE_PRINTK_STRING("Stopping rcu_torture_boost task");
1439         t = boost_tasks[cpu];
1440         boost_tasks[cpu] = NULL;
1441         mutex_unlock(&boost_mutex);
1442
1443         /* This must be outside of the mutex, otherwise deadlock! */
1444         kthread_stop(t);
1445         boost_tasks[cpu] = NULL;
1446 }
1447
1448 static int rcutorture_booster_init(int cpu)
1449 {
1450         int retval;
1451
1452         if (boost_tasks[cpu] != NULL)
1453                 return 0;  /* Already created, nothing more to do. */
1454
1455         /* Don't allow time recalculation while creating a new task. */
1456         mutex_lock(&boost_mutex);
1457         VERBOSE_PRINTK_STRING("Creating rcu_torture_boost task");
1458         boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1459                                                   cpu_to_node(cpu),
1460                                                   "rcu_torture_boost");
1461         if (IS_ERR(boost_tasks[cpu])) {
1462                 retval = PTR_ERR(boost_tasks[cpu]);
1463                 VERBOSE_PRINTK_STRING("rcu_torture_boost task create failed");
1464                 n_rcu_torture_boost_ktrerror++;
1465                 boost_tasks[cpu] = NULL;
1466                 mutex_unlock(&boost_mutex);
1467                 return retval;
1468         }
1469         kthread_bind(boost_tasks[cpu], cpu);
1470         wake_up_process(boost_tasks[cpu]);
1471         mutex_unlock(&boost_mutex);
1472         return 0;
1473 }
1474
1475 /*
1476  * Cause the rcutorture test to shutdown the system after the test has
1477  * run for the time specified by the shutdown_secs module parameter.
1478  */
1479 static int
1480 rcu_torture_shutdown(void *arg)
1481 {
1482         long delta;
1483         unsigned long jiffies_snap;
1484
1485         VERBOSE_PRINTK_STRING("rcu_torture_shutdown task started");
1486         jiffies_snap = ACCESS_ONCE(jiffies);
1487         while (ULONG_CMP_LT(jiffies_snap, shutdown_time) &&
1488                !kthread_should_stop()) {
1489                 delta = shutdown_time - jiffies_snap;
1490                 if (verbose)
1491                         pr_alert("%s" TORTURE_FLAG
1492                                  "rcu_torture_shutdown task: %lu jiffies remaining\n",
1493                                  torture_type, delta);
1494                 schedule_timeout_interruptible(delta);
1495                 jiffies_snap = ACCESS_ONCE(jiffies);
1496         }
1497         if (kthread_should_stop()) {
1498                 VERBOSE_PRINTK_STRING("rcu_torture_shutdown task stopping");
1499                 return 0;
1500         }
1501
1502         /* OK, shut down the system. */
1503
1504         VERBOSE_PRINTK_STRING("rcu_torture_shutdown task shutting down system");
1505         shutdown_task = NULL;   /* Avoid self-kill deadlock. */
1506         rcu_torture_cleanup();  /* Get the success/failure message. */
1507         kernel_power_off();     /* Shut down the system. */
1508         return 0;
1509 }
1510
1511 #ifdef CONFIG_HOTPLUG_CPU
1512
1513 /*
1514  * Execute random CPU-hotplug operations at the interval specified
1515  * by the onoff_interval.
1516  */
1517 static int __cpuinit
1518 rcu_torture_onoff(void *arg)
1519 {
1520         int cpu;
1521         unsigned long delta;
1522         int maxcpu = -1;
1523         DEFINE_RCU_RANDOM(rand);
1524         int ret;
1525         unsigned long starttime;
1526
1527         VERBOSE_PRINTK_STRING("rcu_torture_onoff task started");
1528         for_each_online_cpu(cpu)
1529                 maxcpu = cpu;
1530         WARN_ON(maxcpu < 0);
1531         if (onoff_holdoff > 0) {
1532                 VERBOSE_PRINTK_STRING("rcu_torture_onoff begin holdoff");
1533                 schedule_timeout_interruptible(onoff_holdoff * HZ);
1534                 VERBOSE_PRINTK_STRING("rcu_torture_onoff end holdoff");
1535         }
1536         while (!kthread_should_stop()) {
1537                 cpu = (rcu_random(&rand) >> 4) % (maxcpu + 1);
1538                 if (cpu_online(cpu) && cpu_is_hotpluggable(cpu)) {
1539                         if (verbose)
1540                                 pr_alert("%s" TORTURE_FLAG
1541                                          "rcu_torture_onoff task: offlining %d\n",
1542                                          torture_type, cpu);
1543                         starttime = jiffies;
1544                         n_offline_attempts++;
1545                         ret = cpu_down(cpu);
1546                         if (ret) {
1547                                 if (verbose)
1548                                         pr_alert("%s" TORTURE_FLAG
1549                                                  "rcu_torture_onoff task: offline %d failed: errno %d\n",
1550                                                  torture_type, cpu, ret);
1551                         } else {
1552                                 if (verbose)
1553                                         pr_alert("%s" TORTURE_FLAG
1554                                                  "rcu_torture_onoff task: offlined %d\n",
1555                                                  torture_type, cpu);
1556                                 n_offline_successes++;
1557                                 delta = jiffies - starttime;
1558                                 sum_offline += delta;
1559                                 if (min_offline < 0) {
1560                                         min_offline = delta;
1561                                         max_offline = delta;
1562                                 }
1563                                 if (min_offline > delta)
1564                                         min_offline = delta;
1565                                 if (max_offline < delta)
1566                                         max_offline = delta;
1567                         }
1568                 } else if (cpu_is_hotpluggable(cpu)) {
1569                         if (verbose)
1570                                 pr_alert("%s" TORTURE_FLAG
1571                                          "rcu_torture_onoff task: onlining %d\n",
1572                                          torture_type, cpu);
1573                         starttime = jiffies;
1574                         n_online_attempts++;
1575                         if (cpu_up(cpu) == 0) {
1576                                 if (verbose)
1577                                         pr_alert("%s" TORTURE_FLAG
1578                                                  "rcu_torture_onoff task: onlined %d\n",
1579                                                  torture_type, cpu);
1580                                 n_online_successes++;
1581                                 delta = jiffies - starttime;
1582                                 sum_online += delta;
1583                                 if (min_online < 0) {
1584                                         min_online = delta;
1585                                         max_online = delta;
1586                                 }
1587                                 if (min_online > delta)
1588                                         min_online = delta;
1589                                 if (max_online < delta)
1590                                         max_online = delta;
1591                         }
1592                 }
1593                 schedule_timeout_interruptible(onoff_interval * HZ);
1594         }
1595         VERBOSE_PRINTK_STRING("rcu_torture_onoff task stopping");
1596         return 0;
1597 }
1598
1599 static int __cpuinit
1600 rcu_torture_onoff_init(void)
1601 {
1602         int ret;
1603
1604         if (onoff_interval <= 0)
1605                 return 0;
1606         onoff_task = kthread_run(rcu_torture_onoff, NULL, "rcu_torture_onoff");
1607         if (IS_ERR(onoff_task)) {
1608                 ret = PTR_ERR(onoff_task);
1609                 onoff_task = NULL;
1610                 return ret;
1611         }
1612         return 0;
1613 }
1614
1615 static void rcu_torture_onoff_cleanup(void)
1616 {
1617         if (onoff_task == NULL)
1618                 return;
1619         VERBOSE_PRINTK_STRING("Stopping rcu_torture_onoff task");
1620         kthread_stop(onoff_task);
1621         onoff_task = NULL;
1622 }
1623
1624 #else /* #ifdef CONFIG_HOTPLUG_CPU */
1625
1626 static int
1627 rcu_torture_onoff_init(void)
1628 {
1629         return 0;
1630 }
1631
1632 static void rcu_torture_onoff_cleanup(void)
1633 {
1634 }
1635
1636 #endif /* #else #ifdef CONFIG_HOTPLUG_CPU */
1637
1638 /*
1639  * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
1640  * induces a CPU stall for the time specified by stall_cpu.
1641  */
1642 static int __cpuinit rcu_torture_stall(void *args)
1643 {
1644         unsigned long stop_at;
1645
1646         VERBOSE_PRINTK_STRING("rcu_torture_stall task started");
1647         if (stall_cpu_holdoff > 0) {
1648                 VERBOSE_PRINTK_STRING("rcu_torture_stall begin holdoff");
1649                 schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1650                 VERBOSE_PRINTK_STRING("rcu_torture_stall end holdoff");
1651         }
1652         if (!kthread_should_stop()) {
1653                 stop_at = get_seconds() + stall_cpu;
1654                 /* RCU CPU stall is expected behavior in following code. */
1655                 pr_alert("rcu_torture_stall start.\n");
1656                 rcu_read_lock();
1657                 preempt_disable();
1658                 while (ULONG_CMP_LT(get_seconds(), stop_at))
1659                         continue;  /* Induce RCU CPU stall warning. */
1660                 preempt_enable();
1661                 rcu_read_unlock();
1662                 pr_alert("rcu_torture_stall end.\n");
1663         }
1664         rcutorture_shutdown_absorb("rcu_torture_stall");
1665         while (!kthread_should_stop())
1666                 schedule_timeout_interruptible(10 * HZ);
1667         return 0;
1668 }
1669
1670 /* Spawn CPU-stall kthread, if stall_cpu specified. */
1671 static int __init rcu_torture_stall_init(void)
1672 {
1673         int ret;
1674
1675         if (stall_cpu <= 0)
1676                 return 0;
1677         stall_task = kthread_run(rcu_torture_stall, NULL, "rcu_torture_stall");
1678         if (IS_ERR(stall_task)) {
1679                 ret = PTR_ERR(stall_task);
1680                 stall_task = NULL;
1681                 return ret;
1682         }
1683         return 0;
1684 }
1685
1686 /* Clean up after the CPU-stall kthread, if one was spawned. */
1687 static void rcu_torture_stall_cleanup(void)
1688 {
1689         if (stall_task == NULL)
1690                 return;
1691         VERBOSE_PRINTK_STRING("Stopping rcu_torture_stall_task.");
1692         kthread_stop(stall_task);
1693         stall_task = NULL;
1694 }
1695
1696 /* Callback function for RCU barrier testing. */
1697 void rcu_torture_barrier_cbf(struct rcu_head *rcu)
1698 {
1699         atomic_inc(&barrier_cbs_invoked);
1700 }
1701
1702 /* kthread function to register callbacks used to test RCU barriers. */
1703 static int rcu_torture_barrier_cbs(void *arg)
1704 {
1705         long myid = (long)arg;
1706         bool lastphase = 0;
1707         struct rcu_head rcu;
1708
1709         init_rcu_head_on_stack(&rcu);
1710         VERBOSE_PRINTK_STRING("rcu_torture_barrier_cbs task started");
1711         set_user_nice(current, 19);
1712         do {
1713                 wait_event(barrier_cbs_wq[myid],
1714                            barrier_phase != lastphase ||
1715                            kthread_should_stop() ||
1716                            fullstop != FULLSTOP_DONTSTOP);
1717                 lastphase = barrier_phase;
1718                 smp_mb(); /* ensure barrier_phase load before ->call(). */
1719                 if (kthread_should_stop() || fullstop != FULLSTOP_DONTSTOP)
1720                         break;
1721                 cur_ops->call(&rcu, rcu_torture_barrier_cbf);
1722                 if (atomic_dec_and_test(&barrier_cbs_count))
1723                         wake_up(&barrier_wq);
1724         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1725         VERBOSE_PRINTK_STRING("rcu_torture_barrier_cbs task stopping");
1726         rcutorture_shutdown_absorb("rcu_torture_barrier_cbs");
1727         while (!kthread_should_stop())
1728                 schedule_timeout_interruptible(1);
1729         cur_ops->cb_barrier();
1730         destroy_rcu_head_on_stack(&rcu);
1731         return 0;
1732 }
1733
1734 /* kthread function to drive and coordinate RCU barrier testing. */
1735 static int rcu_torture_barrier(void *arg)
1736 {
1737         int i;
1738
1739         VERBOSE_PRINTK_STRING("rcu_torture_barrier task starting");
1740         do {
1741                 atomic_set(&barrier_cbs_invoked, 0);
1742                 atomic_set(&barrier_cbs_count, n_barrier_cbs);
1743                 smp_mb(); /* Ensure barrier_phase after prior assignments. */
1744                 barrier_phase = !barrier_phase;
1745                 for (i = 0; i < n_barrier_cbs; i++)
1746                         wake_up(&barrier_cbs_wq[i]);
1747                 wait_event(barrier_wq,
1748                            atomic_read(&barrier_cbs_count) == 0 ||
1749                            kthread_should_stop() ||
1750                            fullstop != FULLSTOP_DONTSTOP);
1751                 if (kthread_should_stop() || fullstop != FULLSTOP_DONTSTOP)
1752                         break;
1753                 n_barrier_attempts++;
1754                 cur_ops->cb_barrier();
1755                 if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
1756                         n_rcu_torture_barrier_error++;
1757                         WARN_ON_ONCE(1);
1758                 }
1759                 n_barrier_successes++;
1760                 schedule_timeout_interruptible(HZ / 10);
1761         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1762         VERBOSE_PRINTK_STRING("rcu_torture_barrier task stopping");
1763         rcutorture_shutdown_absorb("rcu_torture_barrier");
1764         while (!kthread_should_stop())
1765                 schedule_timeout_interruptible(1);
1766         return 0;
1767 }
1768
1769 /* Initialize RCU barrier testing. */
1770 static int rcu_torture_barrier_init(void)
1771 {
1772         int i;
1773         int ret;
1774
1775         if (n_barrier_cbs == 0)
1776                 return 0;
1777         if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
1778                 pr_alert("%s" TORTURE_FLAG
1779                          " Call or barrier ops missing for %s,\n",
1780                          torture_type, cur_ops->name);
1781                 pr_alert("%s" TORTURE_FLAG
1782                          " RCU barrier testing omitted from run.\n",
1783                          torture_type);
1784                 return 0;
1785         }
1786         atomic_set(&barrier_cbs_count, 0);
1787         atomic_set(&barrier_cbs_invoked, 0);
1788         barrier_cbs_tasks =
1789                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_tasks[0]),
1790                         GFP_KERNEL);
1791         barrier_cbs_wq =
1792                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_wq[0]),
1793                         GFP_KERNEL);
1794         if (barrier_cbs_tasks == NULL || !barrier_cbs_wq)
1795                 return -ENOMEM;
1796         for (i = 0; i < n_barrier_cbs; i++) {
1797                 init_waitqueue_head(&barrier_cbs_wq[i]);
1798                 barrier_cbs_tasks[i] = kthread_run(rcu_torture_barrier_cbs,
1799                                                    (void *)(long)i,
1800                                                    "rcu_torture_barrier_cbs");
1801                 if (IS_ERR(barrier_cbs_tasks[i])) {
1802                         ret = PTR_ERR(barrier_cbs_tasks[i]);
1803                         VERBOSE_PRINTK_ERRSTRING("Failed to create rcu_torture_barrier_cbs");
1804                         barrier_cbs_tasks[i] = NULL;
1805                         return ret;
1806                 }
1807         }
1808         barrier_task = kthread_run(rcu_torture_barrier, NULL,
1809                                    "rcu_torture_barrier");
1810         if (IS_ERR(barrier_task)) {
1811                 ret = PTR_ERR(barrier_task);
1812                 VERBOSE_PRINTK_ERRSTRING("Failed to create rcu_torture_barrier");
1813                 barrier_task = NULL;
1814         }
1815         return 0;
1816 }
1817
1818 /* Clean up after RCU barrier testing. */
1819 static void rcu_torture_barrier_cleanup(void)
1820 {
1821         int i;
1822
1823         if (barrier_task != NULL) {
1824                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_barrier task");
1825                 kthread_stop(barrier_task);
1826                 barrier_task = NULL;
1827         }
1828         if (barrier_cbs_tasks != NULL) {
1829                 for (i = 0; i < n_barrier_cbs; i++) {
1830                         if (barrier_cbs_tasks[i] != NULL) {
1831                                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_barrier_cbs task");
1832                                 kthread_stop(barrier_cbs_tasks[i]);
1833                                 barrier_cbs_tasks[i] = NULL;
1834                         }
1835                 }
1836                 kfree(barrier_cbs_tasks);
1837                 barrier_cbs_tasks = NULL;
1838         }
1839         if (barrier_cbs_wq != NULL) {
1840                 kfree(barrier_cbs_wq);
1841                 barrier_cbs_wq = NULL;
1842         }
1843 }
1844
1845 static int rcutorture_cpu_notify(struct notifier_block *self,
1846                                  unsigned long action, void *hcpu)
1847 {
1848         long cpu = (long)hcpu;
1849
1850         switch (action) {
1851         case CPU_ONLINE:
1852         case CPU_DOWN_FAILED:
1853                 (void)rcutorture_booster_init(cpu);
1854                 break;
1855         case CPU_DOWN_PREPARE:
1856                 rcutorture_booster_cleanup(cpu);
1857                 break;
1858         default:
1859                 break;
1860         }
1861         return NOTIFY_OK;
1862 }
1863
1864 static struct notifier_block rcutorture_cpu_nb = {
1865         .notifier_call = rcutorture_cpu_notify,
1866 };
1867
1868 static void
1869 rcu_torture_cleanup(void)
1870 {
1871         int i;
1872
1873         mutex_lock(&fullstop_mutex);
1874         rcutorture_record_test_transition();
1875         if (fullstop == FULLSTOP_SHUTDOWN) {
1876                 pr_warn(/* but going down anyway, so... */
1877                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
1878                 mutex_unlock(&fullstop_mutex);
1879                 schedule_timeout_uninterruptible(10);
1880                 if (cur_ops->cb_barrier != NULL)
1881                         cur_ops->cb_barrier();
1882                 return;
1883         }
1884         fullstop = FULLSTOP_RMMOD;
1885         mutex_unlock(&fullstop_mutex);
1886         unregister_reboot_notifier(&rcutorture_shutdown_nb);
1887         rcu_torture_barrier_cleanup();
1888         rcu_torture_stall_cleanup();
1889         if (stutter_task) {
1890                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
1891                 kthread_stop(stutter_task);
1892         }
1893         stutter_task = NULL;
1894         if (shuffler_task) {
1895                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
1896                 kthread_stop(shuffler_task);
1897                 free_cpumask_var(shuffle_tmp_mask);
1898         }
1899         shuffler_task = NULL;
1900
1901         if (writer_task) {
1902                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
1903                 kthread_stop(writer_task);
1904         }
1905         writer_task = NULL;
1906
1907         if (reader_tasks) {
1908                 for (i = 0; i < nrealreaders; i++) {
1909                         if (reader_tasks[i]) {
1910                                 VERBOSE_PRINTK_STRING(
1911                                         "Stopping rcu_torture_reader task");
1912                                 kthread_stop(reader_tasks[i]);
1913                         }
1914                         reader_tasks[i] = NULL;
1915                 }
1916                 kfree(reader_tasks);
1917                 reader_tasks = NULL;
1918         }
1919         rcu_torture_current = NULL;
1920
1921         if (fakewriter_tasks) {
1922                 for (i = 0; i < nfakewriters; i++) {
1923                         if (fakewriter_tasks[i]) {
1924                                 VERBOSE_PRINTK_STRING(
1925                                         "Stopping rcu_torture_fakewriter task");
1926                                 kthread_stop(fakewriter_tasks[i]);
1927                         }
1928                         fakewriter_tasks[i] = NULL;
1929                 }
1930                 kfree(fakewriter_tasks);
1931                 fakewriter_tasks = NULL;
1932         }
1933
1934         if (stats_task) {
1935                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
1936                 kthread_stop(stats_task);
1937         }
1938         stats_task = NULL;
1939
1940         if (fqs_task) {
1941                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_fqs task");
1942                 kthread_stop(fqs_task);
1943         }
1944         fqs_task = NULL;
1945         if ((test_boost == 1 && cur_ops->can_boost) ||
1946             test_boost == 2) {
1947                 unregister_cpu_notifier(&rcutorture_cpu_nb);
1948                 for_each_possible_cpu(i)
1949                         rcutorture_booster_cleanup(i);
1950         }
1951         if (shutdown_task != NULL) {
1952                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shutdown task");
1953                 kthread_stop(shutdown_task);
1954         }
1955         shutdown_task = NULL;
1956         rcu_torture_onoff_cleanup();
1957
1958         /* Wait for all RCU callbacks to fire.  */
1959
1960         if (cur_ops->cb_barrier != NULL)
1961                 cur_ops->cb_barrier();
1962
1963         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1964
1965         if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
1966                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1967         else if (n_online_successes != n_online_attempts ||
1968                  n_offline_successes != n_offline_attempts)
1969                 rcu_torture_print_module_parms(cur_ops,
1970                                                "End of test: RCU_HOTPLUG");
1971         else
1972                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1973 }
1974
1975 static int __init
1976 rcu_torture_init(void)
1977 {
1978         int i;
1979         int cpu;
1980         int firsterr = 0;
1981         int retval;
1982         static struct rcu_torture_ops *torture_ops[] =
1983                 { &rcu_ops, &rcu_sync_ops, &rcu_expedited_ops,
1984                   &rcu_bh_ops, &rcu_bh_sync_ops, &rcu_bh_expedited_ops,
1985                   &srcu_ops, &srcu_sync_ops, &srcu_expedited_ops,
1986                   &srcu_raw_ops, &srcu_raw_sync_ops,
1987                   &sched_ops, &sched_sync_ops, &sched_expedited_ops, };
1988
1989         mutex_lock(&fullstop_mutex);
1990
1991         /* Process args and tell the world that the torturer is on the job. */
1992         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1993                 cur_ops = torture_ops[i];
1994                 if (strcmp(torture_type, cur_ops->name) == 0)
1995                         break;
1996         }
1997         if (i == ARRAY_SIZE(torture_ops)) {
1998                 pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
1999                          torture_type);
2000                 pr_alert("rcu-torture types:");
2001                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
2002                         pr_alert(" %s", torture_ops[i]->name);
2003                 pr_alert("\n");
2004                 mutex_unlock(&fullstop_mutex);
2005                 return -EINVAL;
2006         }
2007         if (cur_ops->fqs == NULL && fqs_duration != 0) {
2008                 pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
2009                 fqs_duration = 0;
2010         }
2011         if (cur_ops->init)
2012                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
2013
2014         if (nreaders >= 0)
2015                 nrealreaders = nreaders;
2016         else
2017                 nrealreaders = 2 * num_online_cpus();
2018         rcu_torture_print_module_parms(cur_ops, "Start of test");
2019         fullstop = FULLSTOP_DONTSTOP;
2020
2021         /* Set up the freelist. */
2022
2023         INIT_LIST_HEAD(&rcu_torture_freelist);
2024         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
2025                 rcu_tortures[i].rtort_mbtest = 0;
2026                 list_add_tail(&rcu_tortures[i].rtort_free,
2027                               &rcu_torture_freelist);
2028         }
2029
2030         /* Initialize the statistics so that each run gets its own numbers. */
2031
2032         rcu_torture_current = NULL;
2033         rcu_torture_current_version = 0;
2034         atomic_set(&n_rcu_torture_alloc, 0);
2035         atomic_set(&n_rcu_torture_alloc_fail, 0);
2036         atomic_set(&n_rcu_torture_free, 0);
2037         atomic_set(&n_rcu_torture_mberror, 0);
2038         atomic_set(&n_rcu_torture_error, 0);
2039         n_rcu_torture_barrier_error = 0;
2040         n_rcu_torture_boost_ktrerror = 0;
2041         n_rcu_torture_boost_rterror = 0;
2042         n_rcu_torture_boost_failure = 0;
2043         n_rcu_torture_boosts = 0;
2044         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
2045                 atomic_set(&rcu_torture_wcount[i], 0);
2046         for_each_possible_cpu(cpu) {
2047                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
2048                         per_cpu(rcu_torture_count, cpu)[i] = 0;
2049                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
2050                 }
2051         }
2052
2053         /* Start up the kthreads. */
2054
2055         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
2056         writer_task = kthread_create(rcu_torture_writer, NULL,
2057                                      "rcu_torture_writer");
2058         if (IS_ERR(writer_task)) {
2059                 firsterr = PTR_ERR(writer_task);
2060                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
2061                 writer_task = NULL;
2062                 goto unwind;
2063         }
2064         wake_up_process(writer_task);
2065         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
2066                                    GFP_KERNEL);
2067         if (fakewriter_tasks == NULL) {
2068                 VERBOSE_PRINTK_ERRSTRING("out of memory");
2069                 firsterr = -ENOMEM;
2070                 goto unwind;
2071         }
2072         for (i = 0; i < nfakewriters; i++) {
2073                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
2074                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
2075                                                   "rcu_torture_fakewriter");
2076                 if (IS_ERR(fakewriter_tasks[i])) {
2077                         firsterr = PTR_ERR(fakewriter_tasks[i]);
2078                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
2079                         fakewriter_tasks[i] = NULL;
2080                         goto unwind;
2081                 }
2082         }
2083         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
2084                                GFP_KERNEL);
2085         if (reader_tasks == NULL) {
2086                 VERBOSE_PRINTK_ERRSTRING("out of memory");
2087                 firsterr = -ENOMEM;
2088                 goto unwind;
2089         }
2090         for (i = 0; i < nrealreaders; i++) {
2091                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
2092                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
2093                                               "rcu_torture_reader");
2094                 if (IS_ERR(reader_tasks[i])) {
2095                         firsterr = PTR_ERR(reader_tasks[i]);
2096                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
2097                         reader_tasks[i] = NULL;
2098                         goto unwind;
2099                 }
2100         }
2101         if (stat_interval > 0) {
2102                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
2103                 stats_task = kthread_run(rcu_torture_stats, NULL,
2104                                         "rcu_torture_stats");
2105                 if (IS_ERR(stats_task)) {
2106                         firsterr = PTR_ERR(stats_task);
2107                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
2108                         stats_task = NULL;
2109                         goto unwind;
2110                 }
2111         }
2112         if (test_no_idle_hz) {
2113                 rcu_idle_cpu = num_online_cpus() - 1;
2114
2115                 if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
2116                         firsterr = -ENOMEM;
2117                         VERBOSE_PRINTK_ERRSTRING("Failed to alloc mask");
2118                         goto unwind;
2119                 }
2120
2121                 /* Create the shuffler thread */
2122                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
2123                                           "rcu_torture_shuffle");
2124                 if (IS_ERR(shuffler_task)) {
2125                         free_cpumask_var(shuffle_tmp_mask);
2126                         firsterr = PTR_ERR(shuffler_task);
2127                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
2128                         shuffler_task = NULL;
2129                         goto unwind;
2130                 }
2131         }
2132         if (stutter < 0)
2133                 stutter = 0;
2134         if (stutter) {
2135                 /* Create the stutter thread */
2136                 stutter_task = kthread_run(rcu_torture_stutter, NULL,
2137                                           "rcu_torture_stutter");
2138                 if (IS_ERR(stutter_task)) {
2139                         firsterr = PTR_ERR(stutter_task);
2140                         VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
2141                         stutter_task = NULL;
2142                         goto unwind;
2143                 }
2144         }
2145         if (fqs_duration < 0)
2146                 fqs_duration = 0;
2147         if (fqs_duration) {
2148                 /* Create the stutter thread */
2149                 fqs_task = kthread_run(rcu_torture_fqs, NULL,
2150                                        "rcu_torture_fqs");
2151                 if (IS_ERR(fqs_task)) {
2152                         firsterr = PTR_ERR(fqs_task);
2153                         VERBOSE_PRINTK_ERRSTRING("Failed to create fqs");
2154                         fqs_task = NULL;
2155                         goto unwind;
2156                 }
2157         }
2158         if (test_boost_interval < 1)
2159                 test_boost_interval = 1;
2160         if (test_boost_duration < 2)
2161                 test_boost_duration = 2;
2162         if ((test_boost == 1 && cur_ops->can_boost) ||
2163             test_boost == 2) {
2164
2165                 boost_starttime = jiffies + test_boost_interval * HZ;
2166                 register_cpu_notifier(&rcutorture_cpu_nb);
2167                 for_each_possible_cpu(i) {
2168                         if (cpu_is_offline(i))
2169                                 continue;  /* Heuristic: CPU can go offline. */
2170                         retval = rcutorture_booster_init(i);
2171                         if (retval < 0) {
2172                                 firsterr = retval;
2173                                 goto unwind;
2174                         }
2175                 }
2176         }
2177         if (shutdown_secs > 0) {
2178                 shutdown_time = jiffies + shutdown_secs * HZ;
2179                 shutdown_task = kthread_create(rcu_torture_shutdown, NULL,
2180                                                "rcu_torture_shutdown");
2181                 if (IS_ERR(shutdown_task)) {
2182                         firsterr = PTR_ERR(shutdown_task);
2183                         VERBOSE_PRINTK_ERRSTRING("Failed to create shutdown");
2184                         shutdown_task = NULL;
2185                         goto unwind;
2186                 }
2187                 wake_up_process(shutdown_task);
2188         }
2189         i = rcu_torture_onoff_init();
2190         if (i != 0) {
2191                 firsterr = i;
2192                 goto unwind;
2193         }
2194         register_reboot_notifier(&rcutorture_shutdown_nb);
2195         i = rcu_torture_stall_init();
2196         if (i != 0) {
2197                 firsterr = i;
2198                 goto unwind;
2199         }
2200         retval = rcu_torture_barrier_init();
2201         if (retval != 0) {
2202                 firsterr = retval;
2203                 goto unwind;
2204         }
2205         rcutorture_record_test_transition();
2206         mutex_unlock(&fullstop_mutex);
2207         return 0;
2208
2209 unwind:
2210         mutex_unlock(&fullstop_mutex);
2211         rcu_torture_cleanup();
2212         return firsterr;
2213 }
2214
2215 module_init(rcu_torture_init);
2216 module_exit(rcu_torture_cleanup);