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 int verbose;             /* Print more debug info. */
  60 static int 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 = 0;    /* Duration of bursts (us), 0 to disable. */
  65 static int fqs_holdoff = 0;     /* Hold time within burst (us). */
  66 static int fqs_stutter = 3;     /* Wait time between bursts (s). */
  67 static int test_boost = 1;      /* Test RCU prio boost: 0=no, 1=maybe, 2=yes. */
  68 static int test_boost_interval = 7; /* Interval between boost tests, seconds. */
  69 static int test_boost_duration = 4; /* Duration of each boost test, seconds. */
  70 static char *torture_type = "rcu"; /* What RCU implementation to torture. */
  71
  72 module_param(nreaders, int, 0444);
  73 MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
  74 module_param(nfakewriters, int, 0444);
  75 MODULE_PARM_DESC(nfakewriters, "Number of RCU fake writer threads");
  76 module_param(stat_interval, int, 0644);
  77 MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
  78 module_param(verbose, bool, 0444);
  79 MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
  80 module_param(test_no_idle_hz, bool, 0444);
  81 MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
  82 module_param(shuffle_interval, int, 0444);
  83 MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
  84 module_param(stutter, int, 0444);
  85 MODULE_PARM_DESC(stutter, "Number of seconds to run/halt test");
  86 module_param(irqreader, int, 0444);
  87 MODULE_PARM_DESC(irqreader, "Allow RCU readers from irq handlers");
  88 module_param(fqs_duration, int, 0444);
  89 MODULE_PARM_DESC(fqs_duration, "Duration of fqs bursts (us)");
  90 module_param(fqs_holdoff, int, 0444);
  91 MODULE_PARM_DESC(fqs_holdoff, "Holdoff time within fqs bursts (us)");
  92 module_param(fqs_stutter, int, 0444);
  93 MODULE_PARM_DESC(fqs_stutter, "Wait time between fqs bursts (s)");
  94 module_param(test_boost, int, 0444);
  95 MODULE_PARM_DESC(test_boost, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
  96 module_param(test_boost_interval, int, 0444);
  97 MODULE_PARM_DESC(test_boost_interval, "Interval between boost tests, seconds.");
  98 module_param(test_boost_duration, int, 0444);
  99 MODULE_PARM_DESC(test_boost_duration, "Duration of each boost test, seconds.");
 100 module_param(torture_type, charp, 0444);
 101 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, srcu)");
 102
 103 #define TORTURE_FLAG "-torture:"
 104 #define PRINTK_STRING(s) \
 105         do { printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
 106 #define VERBOSE_PRINTK_STRING(s) \
 107         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
 108 #define VERBOSE_PRINTK_ERRSTRING(s) \
 109         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
 110
 111 static char printk_buf[4096];
 112
 113 static int nrealreaders;
 114 static struct task_struct *writer_task;
 115 static struct task_struct **fakewriter_tasks;
 116 static struct task_struct **reader_tasks;
 117 static struct task_struct *stats_task;
 118 static struct task_struct *shuffler_task;
 119 static struct task_struct *stutter_task;
 120 static struct task_struct *fqs_task;
 121 static struct task_struct *boost_tasks[NR_CPUS];
 122
 123 #define RCU_TORTURE_PIPE_LEN 10
 124
 125 struct rcu_torture {
 126         struct rcu_head rtort_rcu;
 127         int rtort_pipe_count;
 128         struct list_head rtort_free;
 129         int rtort_mbtest;
 130 };
 131
 132 static LIST_HEAD(rcu_torture_freelist);
 133 static struct rcu_torture __rcu *rcu_torture_current;
 134 static unsigned long rcu_torture_current_version;
 135 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 136 static DEFINE_SPINLOCK(rcu_torture_lock);
 137 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
 138         { 0 };
 139 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) =
 140         { 0 };
 141 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 142 static atomic_t n_rcu_torture_alloc;
 143 static atomic_t n_rcu_torture_alloc_fail;
 144 static atomic_t n_rcu_torture_free;
 145 static atomic_t n_rcu_torture_mberror;
 146 static atomic_t n_rcu_torture_error;
 147 static long n_rcu_torture_boost_ktrerror;
 148 static long n_rcu_torture_boost_rterror;
 149 static long n_rcu_torture_boost_failure;
 150 static long n_rcu_torture_boosts;
 151 static long n_rcu_torture_timers;
 152 static struct list_head rcu_torture_removed;
 153 static cpumask_var_t shuffle_tmp_mask;
 154
 155 static int stutter_pause_test;
 156
 157 #if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
 158 #define RCUTORTURE_RUNNABLE_INIT 1
 159 #else
 160 #define RCUTORTURE_RUNNABLE_INIT 0
 161 #endif
 162 int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT;
 163
 164 #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
 165 #define rcu_can_boost() 1
 166 #else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 167 #define rcu_can_boost() 0
 168 #endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 169
 170 static unsigned long boost_starttime;   /* jiffies of next boost test start. */
 171 DEFINE_MUTEX(boost_mutex);              /* protect setting boost_starttime */
 172                                         /*  and boost task create/destroy. */
 173
 174 /* Mediate rmmod and system shutdown.  Concurrent rmmod & shutdown illegal! */
 175
 176 #define FULLSTOP_DONTSTOP 0     /* Normal operation. */
 177 #define FULLSTOP_SHUTDOWN 1     /* System shutdown with rcutorture running. */
 178 #define FULLSTOP_RMMOD    2     /* Normal rmmod of rcutorture. */
 179 static int fullstop = FULLSTOP_RMMOD;
 180 /*
 181  * Protect fullstop transitions and spawning of kthreads.
 182  */
 183 static DEFINE_MUTEX(fullstop_mutex);
 184
 185 /*
 186  * Detect and respond to a system shutdown.
 187  */
 188 static int
 189 rcutorture_shutdown_notify(struct notifier_block *unused1,
 190                            unsigned long unused2, void *unused3)
 191 {
 192         mutex_lock(&fullstop_mutex);
 193         if (fullstop == FULLSTOP_DONTSTOP)
 194                 fullstop = FULLSTOP_SHUTDOWN;
 195         else
 196                 printk(KERN_WARNING /* but going down anyway, so... */
 197                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
 198         mutex_unlock(&fullstop_mutex);
 199         return NOTIFY_DONE;
 200 }
 201
 202 /*
 203  * Absorb kthreads into a kernel function that won't return, so that
 204  * they won't ever access module text or data again.
 205  */
 206 static void rcutorture_shutdown_absorb(char *title)
 207 {
 208         if (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
 209                 printk(KERN_NOTICE
 210                        "rcutorture thread %s parking due to system shutdown\n",
 211                        title);
 212                 schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
 213         }
 214 }
 215
 216 /*
 217  * Allocate an element from the rcu_tortures pool.
 218  */
 219 static struct rcu_torture *
 220 rcu_torture_alloc(void)
 221 {
 222         struct list_head *p;
 223
 224         spin_lock_bh(&rcu_torture_lock);
 225         if (list_empty(&rcu_torture_freelist)) {
 226                 atomic_inc(&n_rcu_torture_alloc_fail);
 227                 spin_unlock_bh(&rcu_torture_lock);
 228                 return NULL;
 229         }
 230         atomic_inc(&n_rcu_torture_alloc);
 231         p = rcu_torture_freelist.next;
 232         list_del_init(p);
 233         spin_unlock_bh(&rcu_torture_lock);
 234         return container_of(p, struct rcu_torture, rtort_free);
 235 }
 236
 237 /*
 238  * Free an element to the rcu_tortures pool.
 239  */
 240 static void
 241 rcu_torture_free(struct rcu_torture *p)
 242 {
 243         atomic_inc(&n_rcu_torture_free);
 244         spin_lock_bh(&rcu_torture_lock);
 245         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 246         spin_unlock_bh(&rcu_torture_lock);
 247 }
 248
 249 struct rcu_random_state {
 250         unsigned long rrs_state;
 251         long rrs_count;
 252 };
 253
 254 #define RCU_RANDOM_MULT 39916801  /* prime */
 255 #define RCU_RANDOM_ADD  479001701 /* prime */
 256 #define RCU_RANDOM_REFRESH 10000
 257
 258 #define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
 259
 260 /*
 261  * Crude but fast random-number generator.  Uses a linear congruential
 262  * generator, with occasional help from cpu_clock().
 263  */
 264 static unsigned long
 265 rcu_random(struct rcu_random_state *rrsp)
 266 {
 267         if (--rrsp->rrs_count < 0) {
 268                 rrsp->rrs_state += (unsigned long)local_clock();
 269                 rrsp->rrs_count = RCU_RANDOM_REFRESH;
 270         }
 271         rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
 272         return swahw32(rrsp->rrs_state);
 273 }
 274
 275 static void
 276 rcu_stutter_wait(char *title)
 277 {
 278         while (stutter_pause_test || !rcutorture_runnable) {
 279                 if (rcutorture_runnable)
 280                         schedule_timeout_interruptible(1);
 281                 else
 282                         schedule_timeout_interruptible(round_jiffies_relative(HZ));
 283                 rcutorture_shutdown_absorb(title);
 284         }
 285 }
 286
 287 /*
 288  * Operations vector for selecting different types of tests.
 289  */
 290
 291 struct rcu_torture_ops {
 292         void (*init)(void);
 293         void (*cleanup)(void);
 294         int (*readlock)(void);
 295         void (*read_delay)(struct rcu_random_state *rrsp);
 296         void (*readunlock)(int idx);
 297         int (*completed)(void);
 298         void (*deferred_free)(struct rcu_torture *p);
 299         void (*sync)(void);
 300         void (*cb_barrier)(void);
 301         void (*fqs)(void);
 302         int (*stats)(char *page);
 303         int irq_capable;
 304         int can_boost;
 305         char *name;
 306 };
 307
 308 static struct rcu_torture_ops *cur_ops;
 309
 310 /*
 311  * Definitions for rcu torture testing.
 312  */
 313
 314 static int rcu_torture_read_lock(void) __acquires(RCU)
 315 {
 316         rcu_read_lock();
 317         return 0;
 318 }
 319
 320 static void rcu_read_delay(struct rcu_random_state *rrsp)
 321 {
 322         const unsigned long shortdelay_us = 200;
 323         const unsigned long longdelay_ms = 50;
 324
 325         /* We want a short delay sometimes to make a reader delay the grace
 326          * period, and we want a long delay occasionally to trigger
 327          * force_quiescent_state. */
 328
 329         if (!(rcu_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
 330                 mdelay(longdelay_ms);
 331         if (!(rcu_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
 332                 udelay(shortdelay_us);
 333 #ifdef CONFIG_PREEMPT
 334         if (!preempt_count() && !(rcu_random(rrsp) % (nrealreaders * 20000)))
 335                 preempt_schedule();  /* No QS if preempt_disable() in effect */
 336 #endif
 337 }
 338
 339 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 340 {
 341         rcu_read_unlock();
 342 }
 343
 344 static int rcu_torture_completed(void)
 345 {
 346         return rcu_batches_completed();
 347 }
 348
 349 static void
 350 rcu_torture_cb(struct rcu_head *p)
 351 {
 352         int i;
 353         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 354
 355         if (fullstop != FULLSTOP_DONTSTOP) {
 356                 /* Test is ending, just drop callbacks on the floor. */
 357                 /* The next initialization will pick up the pieces. */
 358                 return;
 359         }
 360         i = rp->rtort_pipe_count;
 361         if (i > RCU_TORTURE_PIPE_LEN)
 362                 i = RCU_TORTURE_PIPE_LEN;
 363         atomic_inc(&rcu_torture_wcount[i]);
 364         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 365                 rp->rtort_mbtest = 0;
 366                 rcu_torture_free(rp);
 367         } else
 368                 cur_ops->deferred_free(rp);
 369 }
 370
 371 static int rcu_no_completed(void)
 372 {
 373         return 0;
 374 }
 375
 376 static void rcu_torture_deferred_free(struct rcu_torture *p)
 377 {
 378         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 379 }
 380
 381 static struct rcu_torture_ops rcu_ops = {
 382         .init           = NULL,
 383         .cleanup        = NULL,
 384         .readlock       = rcu_torture_read_lock,
 385         .read_delay     = rcu_read_delay,
 386         .readunlock     = rcu_torture_read_unlock,
 387         .completed      = rcu_torture_completed,
 388         .deferred_free  = rcu_torture_deferred_free,
 389         .sync           = synchronize_rcu,
 390         .cb_barrier     = rcu_barrier,
 391         .fqs            = rcu_force_quiescent_state,
 392         .stats          = NULL,
 393         .irq_capable    = 1,
 394         .can_boost      = rcu_can_boost(),
 395         .name           = "rcu"
 396 };
 397
 398 static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
 399 {
 400         int i;
 401         struct rcu_torture *rp;
 402         struct rcu_torture *rp1;
 403
 404         cur_ops->sync();
 405         list_add(&p->rtort_free, &rcu_torture_removed);
 406         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 407                 i = rp->rtort_pipe_count;
 408                 if (i > RCU_TORTURE_PIPE_LEN)
 409                         i = RCU_TORTURE_PIPE_LEN;
 410                 atomic_inc(&rcu_torture_wcount[i]);
 411                 if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 412                         rp->rtort_mbtest = 0;
 413                         list_del(&rp->rtort_free);
 414                         rcu_torture_free(rp);
 415                 }
 416         }
 417 }
 418
 419 static void rcu_sync_torture_init(void)
 420 {
 421         INIT_LIST_HEAD(&rcu_torture_removed);
 422 }
 423
 424 static struct rcu_torture_ops rcu_sync_ops = {
 425         .init           = rcu_sync_torture_init,
 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_sync_torture_deferred_free,
 432         .sync           = synchronize_rcu,
 433         .cb_barrier     = NULL,
 434         .fqs            = rcu_force_quiescent_state,
 435         .stats          = NULL,
 436         .irq_capable    = 1,
 437         .can_boost      = rcu_can_boost(),
 438         .name           = "rcu_sync"
 439 };
 440
 441 static struct rcu_torture_ops rcu_expedited_ops = {
 442         .init           = rcu_sync_torture_init,
 443         .cleanup        = NULL,
 444         .readlock       = rcu_torture_read_lock,
 445         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 446         .readunlock     = rcu_torture_read_unlock,
 447         .completed      = rcu_no_completed,
 448         .deferred_free  = rcu_sync_torture_deferred_free,
 449         .sync           = synchronize_rcu_expedited,
 450         .cb_barrier     = NULL,
 451         .fqs            = rcu_force_quiescent_state,
 452         .stats          = NULL,
 453         .irq_capable    = 1,
 454         .can_boost      = rcu_can_boost(),
 455         .name           = "rcu_expedited"
 456 };
 457
 458 /*
 459  * Definitions for rcu_bh torture testing.
 460  */
 461
 462 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
 463 {
 464         rcu_read_lock_bh();
 465         return 0;
 466 }
 467
 468 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
 469 {
 470         rcu_read_unlock_bh();
 471 }
 472
 473 static int rcu_bh_torture_completed(void)
 474 {
 475         return rcu_batches_completed_bh();
 476 }
 477
 478 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 479 {
 480         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
 481 }
 482
 483 static struct rcu_torture_ops rcu_bh_ops = {
 484         .init           = NULL,
 485         .cleanup        = NULL,
 486         .readlock       = rcu_bh_torture_read_lock,
 487         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 488         .readunlock     = rcu_bh_torture_read_unlock,
 489         .completed      = rcu_bh_torture_completed,
 490         .deferred_free  = rcu_bh_torture_deferred_free,
 491         .sync           = synchronize_rcu_bh,
 492         .cb_barrier     = rcu_barrier_bh,
 493         .fqs            = rcu_bh_force_quiescent_state,
 494         .stats          = NULL,
 495         .irq_capable    = 1,
 496         .name           = "rcu_bh"
 497 };
 498
 499 static struct rcu_torture_ops rcu_bh_sync_ops = {
 500         .init           = rcu_sync_torture_init,
 501         .cleanup        = NULL,
 502         .readlock       = rcu_bh_torture_read_lock,
 503         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 504         .readunlock     = rcu_bh_torture_read_unlock,
 505         .completed      = rcu_bh_torture_completed,
 506         .deferred_free  = rcu_sync_torture_deferred_free,
 507         .sync           = synchronize_rcu_bh,
 508         .cb_barrier     = NULL,
 509         .fqs            = rcu_bh_force_quiescent_state,
 510         .stats          = NULL,
 511         .irq_capable    = 1,
 512         .name           = "rcu_bh_sync"
 513 };
 514
 515 static struct rcu_torture_ops rcu_bh_expedited_ops = {
 516         .init           = rcu_sync_torture_init,
 517         .cleanup        = NULL,
 518         .readlock       = rcu_bh_torture_read_lock,
 519         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 520         .readunlock     = rcu_bh_torture_read_unlock,
 521         .completed      = rcu_bh_torture_completed,
 522         .deferred_free  = rcu_sync_torture_deferred_free,
 523         .sync           = synchronize_rcu_bh_expedited,
 524         .cb_barrier     = NULL,
 525         .fqs            = rcu_bh_force_quiescent_state,
 526         .stats          = NULL,
 527         .irq_capable    = 1,
 528         .name           = "rcu_bh_expedited"
 529 };
 530
 531 /*
 532  * Definitions for srcu torture testing.
 533  */
 534
 535 static struct srcu_struct srcu_ctl;
 536
 537 static void srcu_torture_init(void)
 538 {
 539         init_srcu_struct(&srcu_ctl);
 540         rcu_sync_torture_init();
 541 }
 542
 543 static void srcu_torture_cleanup(void)
 544 {
 545         synchronize_srcu(&srcu_ctl);
 546         cleanup_srcu_struct(&srcu_ctl);
 547 }
 548
 549 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
 550 {
 551         return srcu_read_lock(&srcu_ctl);
 552 }
 553
 554 static void srcu_read_delay(struct rcu_random_state *rrsp)
 555 {
 556         long delay;
 557         const long uspertick = 1000000 / HZ;
 558         const long longdelay = 10;
 559
 560         /* We want there to be long-running readers, but not all the time. */
 561
 562         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
 563         if (!delay)
 564                 schedule_timeout_interruptible(longdelay);
 565         else
 566                 rcu_read_delay(rrsp);
 567 }
 568
 569 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
 570 {
 571         srcu_read_unlock(&srcu_ctl, idx);
 572 }
 573
 574 static int srcu_torture_completed(void)
 575 {
 576         return srcu_batches_completed(&srcu_ctl);
 577 }
 578
 579 static void srcu_torture_synchronize(void)
 580 {
 581         synchronize_srcu(&srcu_ctl);
 582 }
 583
 584 static int srcu_torture_stats(char *page)
 585 {
 586         int cnt = 0;
 587         int cpu;
 588         int idx = srcu_ctl.completed & 0x1;
 589
 590         cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
 591                        torture_type, TORTURE_FLAG, idx);
 592         for_each_possible_cpu(cpu) {
 593                 cnt += sprintf(&page[cnt], " %d(%d,%d)", cpu,
 594                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
 595                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
 596         }
 597         cnt += sprintf(&page[cnt], "\n");
 598         return cnt;
 599 }
 600
 601 static struct rcu_torture_ops srcu_ops = {
 602         .init           = srcu_torture_init,
 603         .cleanup        = srcu_torture_cleanup,
 604         .readlock       = srcu_torture_read_lock,
 605         .read_delay     = srcu_read_delay,
 606         .readunlock     = srcu_torture_read_unlock,
 607         .completed      = srcu_torture_completed,
 608         .deferred_free  = rcu_sync_torture_deferred_free,
 609         .sync           = srcu_torture_synchronize,
 610         .cb_barrier     = NULL,
 611         .stats          = srcu_torture_stats,
 612         .name           = "srcu"
 613 };
 614
 615 static void srcu_torture_synchronize_expedited(void)
 616 {
 617         synchronize_srcu_expedited(&srcu_ctl);
 618 }
 619
 620 static struct rcu_torture_ops srcu_expedited_ops = {
 621         .init           = srcu_torture_init,
 622         .cleanup        = srcu_torture_cleanup,
 623         .readlock       = srcu_torture_read_lock,
 624         .read_delay     = srcu_read_delay,
 625         .readunlock     = srcu_torture_read_unlock,
 626         .completed      = srcu_torture_completed,
 627         .deferred_free  = rcu_sync_torture_deferred_free,
 628         .sync           = srcu_torture_synchronize_expedited,
 629         .cb_barrier     = NULL,
 630         .stats          = srcu_torture_stats,
 631         .name           = "srcu_expedited"
 632 };
 633
 634 /*
 635  * Definitions for sched torture testing.
 636  */
 637
 638 static int sched_torture_read_lock(void)
 639 {
 640         preempt_disable();
 641         return 0;
 642 }
 643
 644 static void sched_torture_read_unlock(int idx)
 645 {
 646         preempt_enable();
 647 }
 648
 649 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
 650 {
 651         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
 652 }
 653
 654 static struct rcu_torture_ops sched_ops = {
 655         .init           = rcu_sync_torture_init,
 656         .cleanup        = NULL,
 657         .readlock       = sched_torture_read_lock,
 658         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 659         .readunlock     = sched_torture_read_unlock,
 660         .completed      = rcu_no_completed,
 661         .deferred_free  = rcu_sched_torture_deferred_free,
 662         .sync           = synchronize_sched,
 663         .cb_barrier     = rcu_barrier_sched,
 664         .fqs            = rcu_sched_force_quiescent_state,
 665         .stats          = NULL,
 666         .irq_capable    = 1,
 667         .name           = "sched"
 668 };
 669
 670 static struct rcu_torture_ops sched_sync_ops = {
 671         .init           = rcu_sync_torture_init,
 672         .cleanup        = NULL,
 673         .readlock       = sched_torture_read_lock,
 674         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 675         .readunlock     = sched_torture_read_unlock,
 676         .completed      = rcu_no_completed,
 677         .deferred_free  = rcu_sync_torture_deferred_free,
 678         .sync           = synchronize_sched,
 679         .cb_barrier     = NULL,
 680         .fqs            = rcu_sched_force_quiescent_state,
 681         .stats          = NULL,
 682         .name           = "sched_sync"
 683 };
 684
 685 static struct rcu_torture_ops sched_expedited_ops = {
 686         .init           = rcu_sync_torture_init,
 687         .cleanup        = NULL,
 688         .readlock       = sched_torture_read_lock,
 689         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 690         .readunlock     = sched_torture_read_unlock,
 691         .completed      = rcu_no_completed,
 692         .deferred_free  = rcu_sync_torture_deferred_free,
 693         .sync           = synchronize_sched_expedited,
 694         .cb_barrier     = NULL,
 695         .fqs            = rcu_sched_force_quiescent_state,
 696         .stats          = NULL,
 697         .irq_capable    = 1,
 698         .name           = "sched_expedited"
 699 };
 700
 701 /*
 702  * RCU torture priority-boost testing.  Runs one real-time thread per
 703  * CPU for moderate bursts, repeatedly registering RCU callbacks and
 704  * spinning waiting for them to be invoked.  If a given callback takes
 705  * too long to be invoked, we assume that priority inversion has occurred.
 706  */
 707
 708 struct rcu_boost_inflight {
 709         struct rcu_head rcu;
 710         int inflight;
 711 };
 712
 713 static void rcu_torture_boost_cb(struct rcu_head *head)
 714 {
 715         struct rcu_boost_inflight *rbip =
 716                 container_of(head, struct rcu_boost_inflight, rcu);
 717
 718         smp_mb(); /* Ensure RCU-core accesses precede clearing ->inflight */
 719         rbip->inflight = 0;
 720 }
 721
 722 static int rcu_torture_boost(void *arg)
 723 {
 724         unsigned long call_rcu_time;
 725         unsigned long endtime;
 726         unsigned long oldstarttime;
 727         struct rcu_boost_inflight rbi = { .inflight = 0 };
 728         struct sched_param sp;
 729
 730         VERBOSE_PRINTK_STRING("rcu_torture_boost started");
 731
 732         /* Set real-time priority. */
 733         sp.sched_priority = 1;
 734         if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 735                 VERBOSE_PRINTK_STRING("rcu_torture_boost RT prio failed!");
 736                 n_rcu_torture_boost_rterror++;
 737         }
 738
 739         init_rcu_head_on_stack(&rbi.rcu);
 740         /* Each pass through the following loop does one boost-test cycle. */
 741         do {
 742                 /* Wait for the next test interval. */
 743                 oldstarttime = boost_starttime;
 744                 while (ULONG_CMP_LT(jiffies, oldstarttime)) {
 745                         schedule_timeout_uninterruptible(1);
 746                         rcu_stutter_wait("rcu_torture_boost");
 747                         if (kthread_should_stop() ||
 748                             fullstop != FULLSTOP_DONTSTOP)
 749                                 goto checkwait;
 750                 }
 751
 752                 /* Do one boost-test interval. */
 753                 endtime = oldstarttime + test_boost_duration * HZ;
 754                 call_rcu_time = jiffies;
 755                 while (ULONG_CMP_LT(jiffies, endtime)) {
 756                         /* If we don't have a callback in flight, post one. */
 757                         if (!rbi.inflight) {
 758                                 smp_mb(); /* RCU core before ->inflight = 1. */
 759                                 rbi.inflight = 1;
 760                                 call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 761                                 if (jiffies - call_rcu_time >
 762                                          test_boost_duration * HZ - HZ / 2) {
 763                                         VERBOSE_PRINTK_STRING("rcu_torture_boost boosting failed");
 764                                         n_rcu_torture_boost_failure++;
 765                                 }
 766                                 call_rcu_time = jiffies;
 767                         }
 768                         cond_resched();
 769                         rcu_stutter_wait("rcu_torture_boost");
 770                         if (kthread_should_stop() ||
 771                             fullstop != FULLSTOP_DONTSTOP)
 772                                 goto checkwait;
 773                 }
 774
 775                 /*
 776                  * Set the start time of the next test interval.
 777                  * Yes, this is vulnerable to long delays, but such
 778                  * delays simply cause a false negative for the next
 779                  * interval.  Besides, we are running at RT priority,
 780                  * so delays should be relatively rare.
 781                  */
 782                 while (oldstarttime == boost_starttime &&
 783                        !kthread_should_stop()) {
 784                         if (mutex_trylock(&boost_mutex)) {
 785                                 boost_starttime = jiffies +
 786                                                   test_boost_interval * HZ;
 787                                 n_rcu_torture_boosts++;
 788                                 mutex_unlock(&boost_mutex);
 789                                 break;
 790                         }
 791                         schedule_timeout_uninterruptible(1);
 792                 }
 793
 794                 /* Go do the stutter. */
 795 checkwait:      rcu_stutter_wait("rcu_torture_boost");
 796         } while (!kthread_should_stop() && fullstop  == FULLSTOP_DONTSTOP);
 797
 798         /* Clean up and exit. */
 799         VERBOSE_PRINTK_STRING("rcu_torture_boost task stopping");
 800         rcutorture_shutdown_absorb("rcu_torture_boost");
 801         while (!kthread_should_stop() || rbi.inflight)
 802                 schedule_timeout_uninterruptible(1);
 803         smp_mb(); /* order accesses to ->inflight before stack-frame death. */
 804         destroy_rcu_head_on_stack(&rbi.rcu);
 805         return 0;
 806 }
 807
 808 /*
 809  * RCU torture force-quiescent-state kthread.  Repeatedly induces
 810  * bursts of calls to force_quiescent_state(), increasing the probability
 811  * of occurrence of some important types of race conditions.
 812  */
 813 static int
 814 rcu_torture_fqs(void *arg)
 815 {
 816         unsigned long fqs_resume_time;
 817         int fqs_burst_remaining;
 818
 819         VERBOSE_PRINTK_STRING("rcu_torture_fqs task started");
 820         do {
 821                 fqs_resume_time = jiffies + fqs_stutter * HZ;
 822                 while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
 823                        !kthread_should_stop()) {
 824                         schedule_timeout_interruptible(1);
 825                 }
 826                 fqs_burst_remaining = fqs_duration;
 827                 while (fqs_burst_remaining > 0 &&
 828                        !kthread_should_stop()) {
 829                         cur_ops->fqs();
 830                         udelay(fqs_holdoff);
 831                         fqs_burst_remaining -= fqs_holdoff;
 832                 }
 833                 rcu_stutter_wait("rcu_torture_fqs");
 834         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 835         VERBOSE_PRINTK_STRING("rcu_torture_fqs task stopping");
 836         rcutorture_shutdown_absorb("rcu_torture_fqs");
 837         while (!kthread_should_stop())
 838                 schedule_timeout_uninterruptible(1);
 839         return 0;
 840 }
 841
 842 /*
 843  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 844  * for that pointed to by rcu_torture_current, freeing the old structure
 845  * after a series of grace periods (the "pipeline").
 846  */
 847 static int
 848 rcu_torture_writer(void *arg)
 849 {
 850         int i;
 851         long oldbatch = rcu_batches_completed();
 852         struct rcu_torture *rp;
 853         struct rcu_torture *old_rp;
 854         static DEFINE_RCU_RANDOM(rand);
 855
 856         VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
 857         set_user_nice(current, 19);
 858
 859         do {
 860                 schedule_timeout_uninterruptible(1);
 861                 rp = rcu_torture_alloc();
 862                 if (rp == NULL)
 863                         continue;
 864                 rp->rtort_pipe_count = 0;
 865                 udelay(rcu_random(&rand) & 0x3ff);
 866                 old_rp = rcu_dereference_check(rcu_torture_current,
 867                                                current == writer_task);
 868                 rp->rtort_mbtest = 1;
 869                 rcu_assign_pointer(rcu_torture_current, rp);
 870                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
 871                 if (old_rp) {
 872                         i = old_rp->rtort_pipe_count;
 873                         if (i > RCU_TORTURE_PIPE_LEN)
 874                                 i = RCU_TORTURE_PIPE_LEN;
 875                         atomic_inc(&rcu_torture_wcount[i]);
 876                         old_rp->rtort_pipe_count++;
 877                         cur_ops->deferred_free(old_rp);
 878                 }
 879                 rcutorture_record_progress(++rcu_torture_current_version);
 880                 oldbatch = cur_ops->completed();
 881                 rcu_stutter_wait("rcu_torture_writer");
 882         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 883         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
 884         rcutorture_shutdown_absorb("rcu_torture_writer");
 885         while (!kthread_should_stop())
 886                 schedule_timeout_uninterruptible(1);
 887         return 0;
 888 }
 889
 890 /*
 891  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
 892  * delay between calls.
 893  */
 894 static int
 895 rcu_torture_fakewriter(void *arg)
 896 {
 897         DEFINE_RCU_RANDOM(rand);
 898
 899         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
 900         set_user_nice(current, 19);
 901
 902         do {
 903                 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
 904                 udelay(rcu_random(&rand) & 0x3ff);
 905                 cur_ops->sync();
 906                 rcu_stutter_wait("rcu_torture_fakewriter");
 907         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 908
 909         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
 910         rcutorture_shutdown_absorb("rcu_torture_fakewriter");
 911         while (!kthread_should_stop())
 912                 schedule_timeout_uninterruptible(1);
 913         return 0;
 914 }
 915
 916 void rcutorture_trace_dump(void)
 917 {
 918         static atomic_t beenhere = ATOMIC_INIT(0);
 919
 920         if (atomic_read(&beenhere))
 921                 return;
 922         if (atomic_xchg(&beenhere, 1) != 0)
 923                 return;
 924         do_trace_rcu_torture_read(cur_ops->name, (struct rcu_head *)~0UL);
 925         ftrace_dump(DUMP_ALL);
 926 }
 927
 928 /*
 929  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
 930  * incrementing the corresponding element of the pipeline array.  The
 931  * counter in the element should never be greater than 1, otherwise, the
 932  * RCU implementation is broken.
 933  */
 934 static void rcu_torture_timer(unsigned long unused)
 935 {
 936         int idx;
 937         int completed;
 938         static DEFINE_RCU_RANDOM(rand);
 939         static DEFINE_SPINLOCK(rand_lock);
 940         struct rcu_torture *p;
 941         int pipe_count;
 942
 943         idx = cur_ops->readlock();
 944         completed = cur_ops->completed();
 945         p = rcu_dereference_check(rcu_torture_current,
 946                                   rcu_read_lock_bh_held() ||
 947                                   rcu_read_lock_sched_held() ||
 948                                   srcu_read_lock_held(&srcu_ctl));
 949         do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu);
 950         if (p == NULL) {
 951                 /* Leave because rcu_torture_writer is not yet underway */
 952                 cur_ops->readunlock(idx);
 953                 return;
 954         }
 955         if (p->rtort_mbtest == 0)
 956                 atomic_inc(&n_rcu_torture_mberror);
 957         spin_lock(&rand_lock);
 958         cur_ops->read_delay(&rand);
 959         n_rcu_torture_timers++;
 960         spin_unlock(&rand_lock);
 961         preempt_disable();
 962         pipe_count = p->rtort_pipe_count;
 963         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
 964                 /* Should not happen, but... */
 965                 pipe_count = RCU_TORTURE_PIPE_LEN;
 966         }
 967         if (pipe_count > 1)
 968                 rcutorture_trace_dump();
 969         __this_cpu_inc(rcu_torture_count[pipe_count]);
 970         completed = cur_ops->completed() - completed;
 971         if (completed > RCU_TORTURE_PIPE_LEN) {
 972                 /* Should not happen, but... */
 973                 completed = RCU_TORTURE_PIPE_LEN;
 974         }
 975         __this_cpu_inc(rcu_torture_batch[completed]);
 976         preempt_enable();
 977         cur_ops->readunlock(idx);
 978 }
 979
 980 /*
 981  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
 982  * incrementing the corresponding element of the pipeline array.  The
 983  * counter in the element should never be greater than 1, otherwise, the
 984  * RCU implementation is broken.
 985  */
 986 static int
 987 rcu_torture_reader(void *arg)
 988 {
 989         int completed;
 990         int idx;
 991         DEFINE_RCU_RANDOM(rand);
 992         struct rcu_torture *p;
 993         int pipe_count;
 994         struct timer_list t;
 995
 996         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
 997         set_user_nice(current, 19);
 998         if (irqreader && cur_ops->irq_capable)
 999                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
1000
1001         do {
1002                 if (irqreader && cur_ops->irq_capable) {
1003                         if (!timer_pending(&t))
1004                                 mod_timer(&t, jiffies + 1);
1005                 }
1006                 idx = cur_ops->readlock();
1007                 completed = cur_ops->completed();
1008                 p = rcu_dereference_check(rcu_torture_current,
1009                                           rcu_read_lock_bh_held() ||
1010                                           rcu_read_lock_sched_held() ||
1011                                           srcu_read_lock_held(&srcu_ctl));
1012                 do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu);
1013                 if (p == NULL) {
1014                         /* Wait for rcu_torture_writer to get underway */
1015                         cur_ops->readunlock(idx);
1016                         schedule_timeout_interruptible(HZ);
1017                         continue;
1018                 }
1019                 if (p->rtort_mbtest == 0)
1020                         atomic_inc(&n_rcu_torture_mberror);
1021                 cur_ops->read_delay(&rand);
1022                 preempt_disable();
1023                 pipe_count = p->rtort_pipe_count;
1024                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1025                         /* Should not happen, but... */
1026                         pipe_count = RCU_TORTURE_PIPE_LEN;
1027                 }
1028                 if (pipe_count > 1)
1029                         rcutorture_trace_dump();
1030                 __this_cpu_inc(rcu_torture_count[pipe_count]);
1031                 completed = cur_ops->completed() - completed;
1032                 if (completed > RCU_TORTURE_PIPE_LEN) {
1033                         /* Should not happen, but... */
1034                         completed = RCU_TORTURE_PIPE_LEN;
1035                 }
1036                 __this_cpu_inc(rcu_torture_batch[completed]);
1037                 preempt_enable();
1038                 cur_ops->readunlock(idx);
1039                 schedule();
1040                 rcu_stutter_wait("rcu_torture_reader");
1041         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1042         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
1043         rcutorture_shutdown_absorb("rcu_torture_reader");
1044         if (irqreader && cur_ops->irq_capable)
1045                 del_timer_sync(&t);
1046         while (!kthread_should_stop())
1047                 schedule_timeout_uninterruptible(1);
1048         return 0;
1049 }
1050
1051 /*
1052  * Create an RCU-torture statistics message in the specified buffer.
1053  */
1054 static int
1055 rcu_torture_printk(char *page)
1056 {
1057         int cnt = 0;
1058         int cpu;
1059         int i;
1060         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1061         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1062
1063         for_each_possible_cpu(cpu) {
1064                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1065                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1066                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1067                 }
1068         }
1069         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1070                 if (pipesummary[i] != 0)
1071                         break;
1072         }
1073         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
1074         cnt += sprintf(&page[cnt],
1075                        "rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d "
1076                        "rtmbe: %d rtbke: %ld rtbre: %ld "
1077                        "rtbf: %ld rtb: %ld nt: %ld",
1078                        rcu_torture_current,
1079                        rcu_torture_current_version,
1080                        list_empty(&rcu_torture_freelist),
1081                        atomic_read(&n_rcu_torture_alloc),
1082                        atomic_read(&n_rcu_torture_alloc_fail),
1083                        atomic_read(&n_rcu_torture_free),
1084                        atomic_read(&n_rcu_torture_mberror),
1085                        n_rcu_torture_boost_ktrerror,
1086                        n_rcu_torture_boost_rterror,
1087                        n_rcu_torture_boost_failure,
1088                        n_rcu_torture_boosts,
1089                        n_rcu_torture_timers);
1090         if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1091             n_rcu_torture_boost_ktrerror != 0 ||
1092             n_rcu_torture_boost_rterror != 0 ||
1093             n_rcu_torture_boost_failure != 0)
1094                 cnt += sprintf(&page[cnt], " !!!");
1095         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1096         if (i > 1) {
1097                 cnt += sprintf(&page[cnt], "!!! ");
1098                 atomic_inc(&n_rcu_torture_error);
1099                 WARN_ON_ONCE(1);
1100         }
1101         cnt += sprintf(&page[cnt], "Reader Pipe: ");
1102         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1103                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
1104         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1105         cnt += sprintf(&page[cnt], "Reader Batch: ");
1106         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1107                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
1108         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1109         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
1110         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1111                 cnt += sprintf(&page[cnt], " %d",
1112                                atomic_read(&rcu_torture_wcount[i]));
1113         }
1114         cnt += sprintf(&page[cnt], "\n");
1115         if (cur_ops->stats)
1116                 cnt += cur_ops->stats(&page[cnt]);
1117         return cnt;
1118 }
1119
1120 /*
1121  * Print torture statistics.  Caller must ensure that there is only
1122  * one call to this function at a given time!!!  This is normally
1123  * accomplished by relying on the module system to only have one copy
1124  * of the module loaded, and then by giving the rcu_torture_stats
1125  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1126  * thread is not running).
1127  */
1128 static void
1129 rcu_torture_stats_print(void)
1130 {
1131         int cnt;
1132
1133         cnt = rcu_torture_printk(printk_buf);
1134         printk(KERN_ALERT "%s", printk_buf);
1135 }
1136
1137 /*
1138  * Periodically prints torture statistics, if periodic statistics printing
1139  * was specified via the stat_interval module parameter.
1140  *
1141  * No need to worry about fullstop here, since this one doesn't reference
1142  * volatile state or register callbacks.
1143  */
1144 static int
1145 rcu_torture_stats(void *arg)
1146 {
1147         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
1148         do {
1149                 schedule_timeout_interruptible(stat_interval * HZ);
1150                 rcu_torture_stats_print();
1151                 rcutorture_shutdown_absorb("rcu_torture_stats");
1152         } while (!kthread_should_stop());
1153         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
1154         return 0;
1155 }
1156
1157 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
1158
1159 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
1160  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
1161  */
1162 static void rcu_torture_shuffle_tasks(void)
1163 {
1164         int i;
1165
1166         cpumask_setall(shuffle_tmp_mask);
1167         get_online_cpus();
1168
1169         /* No point in shuffling if there is only one online CPU (ex: UP) */
1170         if (num_online_cpus() == 1) {
1171                 put_online_cpus();
1172                 return;
1173         }
1174
1175         if (rcu_idle_cpu != -1)
1176                 cpumask_clear_cpu(rcu_idle_cpu, shuffle_tmp_mask);
1177
1178         set_cpus_allowed_ptr(current, shuffle_tmp_mask);
1179
1180         if (reader_tasks) {
1181                 for (i = 0; i < nrealreaders; i++)
1182                         if (reader_tasks[i])
1183                                 set_cpus_allowed_ptr(reader_tasks[i],
1184                                                      shuffle_tmp_mask);
1185         }
1186
1187         if (fakewriter_tasks) {
1188                 for (i = 0; i < nfakewriters; i++)
1189                         if (fakewriter_tasks[i])
1190                                 set_cpus_allowed_ptr(fakewriter_tasks[i],
1191                                                      shuffle_tmp_mask);
1192         }
1193
1194         if (writer_task)
1195                 set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
1196
1197         if (stats_task)
1198                 set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
1199
1200         if (rcu_idle_cpu == -1)
1201                 rcu_idle_cpu = num_online_cpus() - 1;
1202         else
1203                 rcu_idle_cpu--;
1204
1205         put_online_cpus();
1206 }
1207
1208 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
1209  * system to become idle at a time and cut off its timer ticks. This is meant
1210  * to test the support for such tickless idle CPU in RCU.
1211  */
1212 static int
1213 rcu_torture_shuffle(void *arg)
1214 {
1215         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
1216         do {
1217                 schedule_timeout_interruptible(shuffle_interval * HZ);
1218                 rcu_torture_shuffle_tasks();
1219                 rcutorture_shutdown_absorb("rcu_torture_shuffle");
1220         } while (!kthread_should_stop());
1221         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
1222         return 0;
1223 }
1224
1225 /* Cause the rcutorture test to "stutter", starting and stopping all
1226  * threads periodically.
1227  */
1228 static int
1229 rcu_torture_stutter(void *arg)
1230 {
1231         VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
1232         do {
1233                 schedule_timeout_interruptible(stutter * HZ);
1234                 stutter_pause_test = 1;
1235                 if (!kthread_should_stop())
1236                         schedule_timeout_interruptible(stutter * HZ);
1237                 stutter_pause_test = 0;
1238                 rcutorture_shutdown_absorb("rcu_torture_stutter");
1239         } while (!kthread_should_stop());
1240         VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
1241         return 0;
1242 }
1243
1244 static inline void
1245 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, char *tag)
1246 {
1247         printk(KERN_ALERT "%s" TORTURE_FLAG
1248                 "--- %s: nreaders=%d nfakewriters=%d "
1249                 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1250                 "shuffle_interval=%d stutter=%d irqreader=%d "
1251                 "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1252                 "test_boost=%d/%d test_boost_interval=%d "
1253                 "test_boost_duration=%d\n",
1254                 torture_type, tag, nrealreaders, nfakewriters,
1255                 stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1256                 stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1257                 test_boost, cur_ops->can_boost,
1258                 test_boost_interval, test_boost_duration);
1259 }
1260
1261 static struct notifier_block rcutorture_shutdown_nb = {
1262         .notifier_call = rcutorture_shutdown_notify,
1263 };
1264
1265 static void rcutorture_booster_cleanup(int cpu)
1266 {
1267         struct task_struct *t;
1268
1269         if (boost_tasks[cpu] == NULL)
1270                 return;
1271         mutex_lock(&boost_mutex);
1272         VERBOSE_PRINTK_STRING("Stopping rcu_torture_boost task");
1273         t = boost_tasks[cpu];
1274         boost_tasks[cpu] = NULL;
1275         mutex_unlock(&boost_mutex);
1276
1277         /* This must be outside of the mutex, otherwise deadlock! */
1278         kthread_stop(t);
1279 }
1280
1281 static int rcutorture_booster_init(int cpu)
1282 {
1283         int retval;
1284
1285         if (boost_tasks[cpu] != NULL)
1286                 return 0;  /* Already created, nothing more to do. */
1287
1288         /* Don't allow time recalculation while creating a new task. */
1289         mutex_lock(&boost_mutex);
1290         VERBOSE_PRINTK_STRING("Creating rcu_torture_boost task");
1291         boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1292                                                   cpu_to_node(cpu),
1293                                                   "rcu_torture_boost");
1294         if (IS_ERR(boost_tasks[cpu])) {
1295                 retval = PTR_ERR(boost_tasks[cpu]);
1296                 VERBOSE_PRINTK_STRING("rcu_torture_boost task create failed");
1297                 n_rcu_torture_boost_ktrerror++;
1298                 boost_tasks[cpu] = NULL;
1299                 mutex_unlock(&boost_mutex);
1300                 return retval;
1301         }
1302         kthread_bind(boost_tasks[cpu], cpu);
1303         wake_up_process(boost_tasks[cpu]);
1304         mutex_unlock(&boost_mutex);
1305         return 0;
1306 }
1307
1308 static int rcutorture_cpu_notify(struct notifier_block *self,
1309                                  unsigned long action, void *hcpu)
1310 {
1311         long cpu = (long)hcpu;
1312
1313         switch (action) {
1314         case CPU_ONLINE:
1315         case CPU_DOWN_FAILED:
1316                 (void)rcutorture_booster_init(cpu);
1317                 break;
1318         case CPU_DOWN_PREPARE:
1319                 rcutorture_booster_cleanup(cpu);
1320                 break;
1321         default:
1322                 break;
1323         }
1324         return NOTIFY_OK;
1325 }
1326
1327 static struct notifier_block rcutorture_cpu_nb = {
1328         .notifier_call = rcutorture_cpu_notify,
1329 };
1330
1331 static void
1332 rcu_torture_cleanup(void)
1333 {
1334         int i;
1335
1336         mutex_lock(&fullstop_mutex);
1337         rcutorture_record_test_transition();
1338         if (fullstop == FULLSTOP_SHUTDOWN) {
1339                 printk(KERN_WARNING /* but going down anyway, so... */
1340                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
1341                 mutex_unlock(&fullstop_mutex);
1342                 schedule_timeout_uninterruptible(10);
1343                 if (cur_ops->cb_barrier != NULL)
1344                         cur_ops->cb_barrier();
1345                 return;
1346         }
1347         fullstop = FULLSTOP_RMMOD;
1348         mutex_unlock(&fullstop_mutex);
1349         unregister_reboot_notifier(&rcutorture_shutdown_nb);
1350         if (stutter_task) {
1351                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
1352                 kthread_stop(stutter_task);
1353         }
1354         stutter_task = NULL;
1355         if (shuffler_task) {
1356                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
1357                 kthread_stop(shuffler_task);
1358                 free_cpumask_var(shuffle_tmp_mask);
1359         }
1360         shuffler_task = NULL;
1361
1362         if (writer_task) {
1363                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
1364                 kthread_stop(writer_task);
1365         }
1366         writer_task = NULL;
1367
1368         if (reader_tasks) {
1369                 for (i = 0; i < nrealreaders; i++) {
1370                         if (reader_tasks[i]) {
1371                                 VERBOSE_PRINTK_STRING(
1372                                         "Stopping rcu_torture_reader task");
1373                                 kthread_stop(reader_tasks[i]);
1374                         }
1375                         reader_tasks[i] = NULL;
1376                 }
1377                 kfree(reader_tasks);
1378                 reader_tasks = NULL;
1379         }
1380         rcu_torture_current = NULL;
1381
1382         if (fakewriter_tasks) {
1383                 for (i = 0; i < nfakewriters; i++) {
1384                         if (fakewriter_tasks[i]) {
1385                                 VERBOSE_PRINTK_STRING(
1386                                         "Stopping rcu_torture_fakewriter task");
1387                                 kthread_stop(fakewriter_tasks[i]);
1388                         }
1389                         fakewriter_tasks[i] = NULL;
1390                 }
1391                 kfree(fakewriter_tasks);
1392                 fakewriter_tasks = NULL;
1393         }
1394
1395         if (stats_task) {
1396                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
1397                 kthread_stop(stats_task);
1398         }
1399         stats_task = NULL;
1400
1401         if (fqs_task) {
1402                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_fqs task");
1403                 kthread_stop(fqs_task);
1404         }
1405         fqs_task = NULL;
1406         if ((test_boost == 1 && cur_ops->can_boost) ||
1407             test_boost == 2) {
1408                 unregister_cpu_notifier(&rcutorture_cpu_nb);
1409                 for_each_possible_cpu(i)
1410                         rcutorture_booster_cleanup(i);
1411         }
1412
1413         /* Wait for all RCU callbacks to fire.  */
1414
1415         if (cur_ops->cb_barrier != NULL)
1416                 cur_ops->cb_barrier();
1417
1418         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1419
1420         if (cur_ops->cleanup)
1421                 cur_ops->cleanup();
1422         if (atomic_read(&n_rcu_torture_error))
1423                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1424         else
1425                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1426 }
1427
1428 static int __init
1429 rcu_torture_init(void)
1430 {
1431         int i;
1432         int cpu;
1433         int firsterr = 0;
1434         static struct rcu_torture_ops *torture_ops[] =
1435                 { &rcu_ops, &rcu_sync_ops, &rcu_expedited_ops,
1436                   &rcu_bh_ops, &rcu_bh_sync_ops, &rcu_bh_expedited_ops,
1437                   &srcu_ops, &srcu_expedited_ops,
1438                   &sched_ops, &sched_sync_ops, &sched_expedited_ops, };
1439
1440         mutex_lock(&fullstop_mutex);
1441
1442         /* Process args and tell the world that the torturer is on the job. */
1443         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1444                 cur_ops = torture_ops[i];
1445                 if (strcmp(torture_type, cur_ops->name) == 0)
1446                         break;
1447         }
1448         if (i == ARRAY_SIZE(torture_ops)) {
1449                 printk(KERN_ALERT "rcu-torture: invalid torture type: \"%s\"\n",
1450                        torture_type);
1451                 printk(KERN_ALERT "rcu-torture types:");
1452                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1453                         printk(KERN_ALERT " %s", torture_ops[i]->name);
1454                 printk(KERN_ALERT "\n");
1455                 mutex_unlock(&fullstop_mutex);
1456                 return -EINVAL;
1457         }
1458         if (cur_ops->fqs == NULL && fqs_duration != 0) {
1459                 printk(KERN_ALERT "rcu-torture: ->fqs NULL and non-zero "
1460                                   "fqs_duration, fqs disabled.\n");
1461                 fqs_duration = 0;
1462         }
1463         if (cur_ops->init)
1464                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1465
1466         if (nreaders >= 0)
1467                 nrealreaders = nreaders;
1468         else
1469                 nrealreaders = 2 * num_online_cpus();
1470         rcu_torture_print_module_parms(cur_ops, "Start of test");
1471         fullstop = FULLSTOP_DONTSTOP;
1472
1473         /* Set up the freelist. */
1474
1475         INIT_LIST_HEAD(&rcu_torture_freelist);
1476         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1477                 rcu_tortures[i].rtort_mbtest = 0;
1478                 list_add_tail(&rcu_tortures[i].rtort_free,
1479                               &rcu_torture_freelist);
1480         }
1481
1482         /* Initialize the statistics so that each run gets its own numbers. */
1483
1484         rcu_torture_current = NULL;
1485         rcu_torture_current_version = 0;
1486         atomic_set(&n_rcu_torture_alloc, 0);
1487         atomic_set(&n_rcu_torture_alloc_fail, 0);
1488         atomic_set(&n_rcu_torture_free, 0);
1489         atomic_set(&n_rcu_torture_mberror, 0);
1490         atomic_set(&n_rcu_torture_error, 0);
1491         n_rcu_torture_boost_ktrerror = 0;
1492         n_rcu_torture_boost_rterror = 0;
1493         n_rcu_torture_boost_failure = 0;
1494         n_rcu_torture_boosts = 0;
1495         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1496                 atomic_set(&rcu_torture_wcount[i], 0);
1497         for_each_possible_cpu(cpu) {
1498                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1499                         per_cpu(rcu_torture_count, cpu)[i] = 0;
1500                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
1501                 }
1502         }
1503
1504         /* Start up the kthreads. */
1505
1506         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
1507         writer_task = kthread_run(rcu_torture_writer, NULL,
1508                                   "rcu_torture_writer");
1509         if (IS_ERR(writer_task)) {
1510                 firsterr = PTR_ERR(writer_task);
1511                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
1512                 writer_task = NULL;
1513                 goto unwind;
1514         }
1515         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1516                                    GFP_KERNEL);
1517         if (fakewriter_tasks == NULL) {
1518                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1519                 firsterr = -ENOMEM;
1520                 goto unwind;
1521         }
1522         for (i = 0; i < nfakewriters; i++) {
1523                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
1524                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
1525                                                   "rcu_torture_fakewriter");
1526                 if (IS_ERR(fakewriter_tasks[i])) {
1527                         firsterr = PTR_ERR(fakewriter_tasks[i]);
1528                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
1529                         fakewriter_tasks[i] = NULL;
1530                         goto unwind;
1531                 }
1532         }
1533         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1534                                GFP_KERNEL);
1535         if (reader_tasks == NULL) {
1536                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1537                 firsterr = -ENOMEM;
1538                 goto unwind;
1539         }
1540         for (i = 0; i < nrealreaders; i++) {
1541                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
1542                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
1543                                               "rcu_torture_reader");
1544                 if (IS_ERR(reader_tasks[i])) {
1545                         firsterr = PTR_ERR(reader_tasks[i]);
1546                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
1547                         reader_tasks[i] = NULL;
1548                         goto unwind;
1549                 }
1550         }
1551         if (stat_interval > 0) {
1552                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
1553                 stats_task = kthread_run(rcu_torture_stats, NULL,
1554                                         "rcu_torture_stats");
1555                 if (IS_ERR(stats_task)) {
1556                         firsterr = PTR_ERR(stats_task);
1557                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
1558                         stats_task = NULL;
1559                         goto unwind;
1560                 }
1561         }
1562         if (test_no_idle_hz) {
1563                 rcu_idle_cpu = num_online_cpus() - 1;
1564
1565                 if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
1566                         firsterr = -ENOMEM;
1567                         VERBOSE_PRINTK_ERRSTRING("Failed to alloc mask");
1568                         goto unwind;
1569                 }
1570
1571                 /* Create the shuffler thread */
1572                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
1573                                           "rcu_torture_shuffle");
1574                 if (IS_ERR(shuffler_task)) {
1575                         free_cpumask_var(shuffle_tmp_mask);
1576                         firsterr = PTR_ERR(shuffler_task);
1577                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
1578                         shuffler_task = NULL;
1579                         goto unwind;
1580                 }
1581         }
1582         if (stutter < 0)
1583                 stutter = 0;
1584         if (stutter) {
1585                 /* Create the stutter thread */
1586                 stutter_task = kthread_run(rcu_torture_stutter, NULL,
1587                                           "rcu_torture_stutter");
1588                 if (IS_ERR(stutter_task)) {
1589                         firsterr = PTR_ERR(stutter_task);
1590                         VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
1591                         stutter_task = NULL;
1592                         goto unwind;
1593                 }
1594         }
1595         if (fqs_duration < 0)
1596                 fqs_duration = 0;
1597         if (fqs_duration) {
1598                 /* Create the stutter thread */
1599                 fqs_task = kthread_run(rcu_torture_fqs, NULL,
1600                                        "rcu_torture_fqs");
1601                 if (IS_ERR(fqs_task)) {
1602                         firsterr = PTR_ERR(fqs_task);
1603                         VERBOSE_PRINTK_ERRSTRING("Failed to create fqs");
1604                         fqs_task = NULL;
1605                         goto unwind;
1606                 }
1607         }
1608         if (test_boost_interval < 1)
1609                 test_boost_interval = 1;
1610         if (test_boost_duration < 2)
1611                 test_boost_duration = 2;
1612         if ((test_boost == 1 && cur_ops->can_boost) ||
1613             test_boost == 2) {
1614                 int retval;
1615
1616                 boost_starttime = jiffies + test_boost_interval * HZ;
1617                 register_cpu_notifier(&rcutorture_cpu_nb);
1618                 for_each_possible_cpu(i) {
1619                         if (cpu_is_offline(i))
1620                                 continue;  /* Heuristic: CPU can go offline. */
1621                         retval = rcutorture_booster_init(i);
1622                         if (retval < 0) {
1623                                 firsterr = retval;
1624                                 goto unwind;
1625                         }
1626                 }
1627         }
1628         register_reboot_notifier(&rcutorture_shutdown_nb);
1629         rcutorture_record_test_transition();
1630         mutex_unlock(&fullstop_mutex);
1631         return 0;
1632
1633 unwind:
1634         mutex_unlock(&fullstop_mutex);
1635         rcu_torture_cleanup();
1636         return firsterr;
1637 }
1638
1639 module_init(rcu_torture_init);
1640 module_exit(rcu_torture_cleanup);