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