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 <asm/atomic.h>
  37 #include <linux/bitops.h>
  38 #include <linux/module.h>
  39 #include <linux/completion.h>
  40 #include <linux/moduleparam.h>
  41 #include <linux/percpu.h>
  42 #include <linux/notifier.h>
  43 #include <linux/cpu.h>
  44 #include <linux/random.h>
  45 #include <linux/delay.h>
  46 #include <linux/byteorder/swabb.h>
  47 #include <linux/stat.h>
  48 #include <linux/srcu.h>
  49
  50 MODULE_LICENSE("GPL");
  51 MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and "
  52               "Josh Triplett <josh@freedesktop.org>");
  53
  54 static int nreaders = -1;       /* # reader threads, defaults to 2*ncpus */
  55 static int nfakewriters = 4;    /* # fake writer threads */
  56 static int stat_interval;       /* Interval between stats, in seconds. */
  57                                 /*  Defaults to "only at end of test". */
  58 static int verbose;             /* Print more debug info. */
  59 static int test_no_idle_hz;     /* Test RCU's support for tickless idle CPUs. */
  60 static int shuffle_interval = 5; /* Interval between shuffles (in sec)*/
  61 static char *torture_type = "rcu"; /* What to torture: rcu, rcu_bh, srcu. */
  62
  63 module_param(nreaders, int, 0);
  64 MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
  65 module_param(nfakewriters, int, 0);
  66 MODULE_PARM_DESC(nfakewriters, "Number of RCU fake writer threads");
  67 module_param(stat_interval, int, 0);
  68 MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
  69 module_param(verbose, bool, 0);
  70 MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
  71 module_param(test_no_idle_hz, bool, 0);
  72 MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
  73 module_param(shuffle_interval, int, 0);
  74 MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
  75 module_param(torture_type, charp, 0);
  76 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, srcu)");
  77
  78 #define TORTURE_FLAG "-torture:"
  79 #define PRINTK_STRING(s) \
  80         do { printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
  81 #define VERBOSE_PRINTK_STRING(s) \
  82         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
  83 #define VERBOSE_PRINTK_ERRSTRING(s) \
  84         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
  85
  86 static char printk_buf[4096];
  87
  88 static int nrealreaders;
  89 static struct task_struct *writer_task;
  90 static struct task_struct **fakewriter_tasks;
  91 static struct task_struct **reader_tasks;
  92 static struct task_struct *stats_task;
  93 static struct task_struct *shuffler_task;
  94
  95 #define RCU_TORTURE_PIPE_LEN 10
  96
  97 struct rcu_torture {
  98         struct rcu_head rtort_rcu;
  99         int rtort_pipe_count;
 100         struct list_head rtort_free;
 101         int rtort_mbtest;
 102 };
 103
 104 static int fullstop = 0;        /* stop generating callbacks at test end. */
 105 static LIST_HEAD(rcu_torture_freelist);
 106 static struct rcu_torture *rcu_torture_current = NULL;
 107 static long rcu_torture_current_version = 0;
 108 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 109 static DEFINE_SPINLOCK(rcu_torture_lock);
 110 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
 111         { 0 };
 112 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) =
 113         { 0 };
 114 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 115 static atomic_t n_rcu_torture_alloc;
 116 static atomic_t n_rcu_torture_alloc_fail;
 117 static atomic_t n_rcu_torture_free;
 118 static atomic_t n_rcu_torture_mberror;
 119 static atomic_t n_rcu_torture_error;
 120
 121 /*
 122  * Allocate an element from the rcu_tortures pool.
 123  */
 124 static struct rcu_torture *
 125 rcu_torture_alloc(void)
 126 {
 127         struct list_head *p;
 128
 129         spin_lock_bh(&rcu_torture_lock);
 130         if (list_empty(&rcu_torture_freelist)) {
 131                 atomic_inc(&n_rcu_torture_alloc_fail);
 132                 spin_unlock_bh(&rcu_torture_lock);
 133                 return NULL;
 134         }
 135         atomic_inc(&n_rcu_torture_alloc);
 136         p = rcu_torture_freelist.next;
 137         list_del_init(p);
 138         spin_unlock_bh(&rcu_torture_lock);
 139         return container_of(p, struct rcu_torture, rtort_free);
 140 }
 141
 142 /*
 143  * Free an element to the rcu_tortures pool.
 144  */
 145 static void
 146 rcu_torture_free(struct rcu_torture *p)
 147 {
 148         atomic_inc(&n_rcu_torture_free);
 149         spin_lock_bh(&rcu_torture_lock);
 150         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 151         spin_unlock_bh(&rcu_torture_lock);
 152 }
 153
 154 struct rcu_random_state {
 155         unsigned long rrs_state;
 156         long rrs_count;
 157 };
 158
 159 #define RCU_RANDOM_MULT 39916801  /* prime */
 160 #define RCU_RANDOM_ADD  479001701 /* prime */
 161 #define RCU_RANDOM_REFRESH 10000
 162
 163 #define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
 164
 165 /*
 166  * Crude but fast random-number generator.  Uses a linear congruential
 167  * generator, with occasional help from get_random_bytes().
 168  */
 169 static unsigned long
 170 rcu_random(struct rcu_random_state *rrsp)
 171 {
 172         long refresh;
 173
 174         if (--rrsp->rrs_count < 0) {
 175                 get_random_bytes(&refresh, sizeof(refresh));
 176                 rrsp->rrs_state += refresh;
 177                 rrsp->rrs_count = RCU_RANDOM_REFRESH;
 178         }
 179         rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
 180         return swahw32(rrsp->rrs_state);
 181 }
 182
 183 /*
 184  * Operations vector for selecting different types of tests.
 185  */
 186
 187 struct rcu_torture_ops {
 188         void (*init)(void);
 189         void (*cleanup)(void);
 190         int (*readlock)(void);
 191         void (*readdelay)(struct rcu_random_state *rrsp);
 192         void (*readunlock)(int idx);
 193         int (*completed)(void);
 194         void (*deferredfree)(struct rcu_torture *p);
 195         void (*sync)(void);
 196         int (*stats)(char *page);
 197         char *name;
 198 };
 199 static struct rcu_torture_ops *cur_ops = NULL;
 200
 201 /*
 202  * Definitions for rcu torture testing.
 203  */
 204
 205 static int rcu_torture_read_lock(void) __acquires(RCU)
 206 {
 207         rcu_read_lock();
 208         return 0;
 209 }
 210
 211 static void rcu_read_delay(struct rcu_random_state *rrsp)
 212 {
 213         long delay;
 214         const long longdelay = 200;
 215
 216         /* We want there to be long-running readers, but not all the time. */
 217
 218         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay);
 219         if (!delay)
 220                 udelay(longdelay);
 221 }
 222
 223 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 224 {
 225         rcu_read_unlock();
 226 }
 227
 228 static int rcu_torture_completed(void)
 229 {
 230         return rcu_batches_completed();
 231 }
 232
 233 static void
 234 rcu_torture_cb(struct rcu_head *p)
 235 {
 236         int i;
 237         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 238
 239         if (fullstop) {
 240                 /* Test is ending, just drop callbacks on the floor. */
 241                 /* The next initialization will pick up the pieces. */
 242                 return;
 243         }
 244         i = rp->rtort_pipe_count;
 245         if (i > RCU_TORTURE_PIPE_LEN)
 246                 i = RCU_TORTURE_PIPE_LEN;
 247         atomic_inc(&rcu_torture_wcount[i]);
 248         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 249                 rp->rtort_mbtest = 0;
 250                 rcu_torture_free(rp);
 251         } else
 252                 cur_ops->deferredfree(rp);
 253 }
 254
 255 static void rcu_torture_deferred_free(struct rcu_torture *p)
 256 {
 257         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 258 }
 259
 260 static struct rcu_torture_ops rcu_ops = {
 261         .init = NULL,
 262         .cleanup = NULL,
 263         .readlock = rcu_torture_read_lock,
 264         .readdelay = rcu_read_delay,
 265         .readunlock = rcu_torture_read_unlock,
 266         .completed = rcu_torture_completed,
 267         .deferredfree = rcu_torture_deferred_free,
 268         .sync = synchronize_rcu,
 269         .stats = NULL,
 270         .name = "rcu"
 271 };
 272
 273 /*
 274  * Definitions for rcu_bh torture testing.
 275  */
 276
 277 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
 278 {
 279         rcu_read_lock_bh();
 280         return 0;
 281 }
 282
 283 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
 284 {
 285         rcu_read_unlock_bh();
 286 }
 287
 288 static int rcu_bh_torture_completed(void)
 289 {
 290         return rcu_batches_completed_bh();
 291 }
 292
 293 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 294 {
 295         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
 296 }
 297
 298 struct rcu_bh_torture_synchronize {
 299         struct rcu_head head;
 300         struct completion completion;
 301 };
 302
 303 static void rcu_bh_torture_wakeme_after_cb(struct rcu_head *head)
 304 {
 305         struct rcu_bh_torture_synchronize *rcu;
 306
 307         rcu = container_of(head, struct rcu_bh_torture_synchronize, head);
 308         complete(&rcu->completion);
 309 }
 310
 311 static void rcu_bh_torture_synchronize(void)
 312 {
 313         struct rcu_bh_torture_synchronize rcu;
 314
 315         init_completion(&rcu.completion);
 316         call_rcu_bh(&rcu.head, rcu_bh_torture_wakeme_after_cb);
 317         wait_for_completion(&rcu.completion);
 318 }
 319
 320 static struct rcu_torture_ops rcu_bh_ops = {
 321         .init = NULL,
 322         .cleanup = NULL,
 323         .readlock = rcu_bh_torture_read_lock,
 324         .readdelay = rcu_read_delay,  /* just reuse rcu's version. */
 325         .readunlock = rcu_bh_torture_read_unlock,
 326         .completed = rcu_bh_torture_completed,
 327         .deferredfree = rcu_bh_torture_deferred_free,
 328         .sync = rcu_bh_torture_synchronize,
 329         .stats = NULL,
 330         .name = "rcu_bh"
 331 };
 332
 333 /*
 334  * Definitions for srcu torture testing.
 335  */
 336
 337 static struct srcu_struct srcu_ctl;
 338 static struct list_head srcu_removed;
 339
 340 static void srcu_torture_init(void)
 341 {
 342         init_srcu_struct(&srcu_ctl);
 343         INIT_LIST_HEAD(&srcu_removed);
 344 }
 345
 346 static void srcu_torture_cleanup(void)
 347 {
 348         synchronize_srcu(&srcu_ctl);
 349         cleanup_srcu_struct(&srcu_ctl);
 350 }
 351
 352 static int srcu_torture_read_lock(void)
 353 {
 354         return srcu_read_lock(&srcu_ctl);
 355 }
 356
 357 static void srcu_read_delay(struct rcu_random_state *rrsp)
 358 {
 359         long delay;
 360         const long uspertick = 1000000 / HZ;
 361         const long longdelay = 10;
 362
 363         /* We want there to be long-running readers, but not all the time. */
 364
 365         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
 366         if (!delay)
 367                 schedule_timeout_interruptible(longdelay);
 368 }
 369
 370 static void srcu_torture_read_unlock(int idx)
 371 {
 372         srcu_read_unlock(&srcu_ctl, idx);
 373 }
 374
 375 static int srcu_torture_completed(void)
 376 {
 377         return srcu_batches_completed(&srcu_ctl);
 378 }
 379
 380 static void srcu_torture_deferred_free(struct rcu_torture *p)
 381 {
 382         int i;
 383         struct rcu_torture *rp;
 384         struct rcu_torture *rp1;
 385
 386         synchronize_srcu(&srcu_ctl);
 387         list_add(&p->rtort_free, &srcu_removed);
 388         list_for_each_entry_safe(rp, rp1, &srcu_removed, rtort_free) {
 389                 i = rp->rtort_pipe_count;
 390                 if (i > RCU_TORTURE_PIPE_LEN)
 391                         i = RCU_TORTURE_PIPE_LEN;
 392                 atomic_inc(&rcu_torture_wcount[i]);
 393                 if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 394                         rp->rtort_mbtest = 0;
 395                         list_del(&rp->rtort_free);
 396                         rcu_torture_free(rp);
 397                 }
 398         }
 399 }
 400
 401 static void srcu_torture_synchronize(void)
 402 {
 403         synchronize_srcu(&srcu_ctl);
 404 }
 405
 406 static int srcu_torture_stats(char *page)
 407 {
 408         int cnt = 0;
 409         int cpu;
 410         int idx = srcu_ctl.completed & 0x1;
 411
 412         cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
 413                        torture_type, TORTURE_FLAG, idx);
 414         for_each_possible_cpu(cpu) {
 415                 cnt += sprintf(&page[cnt], " %d(%d,%d)", cpu,
 416                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
 417                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
 418         }
 419         cnt += sprintf(&page[cnt], "\n");
 420         return cnt;
 421 }
 422
 423 static struct rcu_torture_ops srcu_ops = {
 424         .init = srcu_torture_init,
 425         .cleanup = srcu_torture_cleanup,
 426         .readlock = srcu_torture_read_lock,
 427         .readdelay = srcu_read_delay,
 428         .readunlock = srcu_torture_read_unlock,
 429         .completed = srcu_torture_completed,
 430         .deferredfree = srcu_torture_deferred_free,
 431         .sync = srcu_torture_synchronize,
 432         .stats = srcu_torture_stats,
 433         .name = "srcu"
 434 };
 435
 436 static struct rcu_torture_ops *torture_ops[] =
 437         { &rcu_ops, &rcu_bh_ops, &srcu_ops, NULL };
 438
 439 /*
 440  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 441  * for that pointed to by rcu_torture_current, freeing the old structure
 442  * after a series of grace periods (the "pipeline").
 443  */
 444 static int
 445 rcu_torture_writer(void *arg)
 446 {
 447         int i;
 448         long oldbatch = rcu_batches_completed();
 449         struct rcu_torture *rp;
 450         struct rcu_torture *old_rp;
 451         static DEFINE_RCU_RANDOM(rand);
 452
 453         VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
 454         set_user_nice(current, 19);
 455
 456         do {
 457                 schedule_timeout_uninterruptible(1);
 458                 if ((rp = rcu_torture_alloc()) == NULL)
 459                         continue;
 460                 rp->rtort_pipe_count = 0;
 461                 udelay(rcu_random(&rand) & 0x3ff);
 462                 old_rp = rcu_torture_current;
 463                 rp->rtort_mbtest = 1;
 464                 rcu_assign_pointer(rcu_torture_current, rp);
 465                 smp_wmb();
 466                 if (old_rp != NULL) {
 467                         i = old_rp->rtort_pipe_count;
 468                         if (i > RCU_TORTURE_PIPE_LEN)
 469                                 i = RCU_TORTURE_PIPE_LEN;
 470                         atomic_inc(&rcu_torture_wcount[i]);
 471                         old_rp->rtort_pipe_count++;
 472                         cur_ops->deferredfree(old_rp);
 473                 }
 474                 rcu_torture_current_version++;
 475                 oldbatch = cur_ops->completed();
 476         } while (!kthread_should_stop() && !fullstop);
 477         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
 478         while (!kthread_should_stop())
 479                 schedule_timeout_uninterruptible(1);
 480         return 0;
 481 }
 482
 483 /*
 484  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
 485  * delay between calls.
 486  */
 487 static int
 488 rcu_torture_fakewriter(void *arg)
 489 {
 490         DEFINE_RCU_RANDOM(rand);
 491
 492         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
 493         set_user_nice(current, 19);
 494
 495         do {
 496                 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
 497                 udelay(rcu_random(&rand) & 0x3ff);
 498                 cur_ops->sync();
 499         } while (!kthread_should_stop() && !fullstop);
 500
 501         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
 502         while (!kthread_should_stop())
 503                 schedule_timeout_uninterruptible(1);
 504         return 0;
 505 }
 506
 507 /*
 508  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
 509  * incrementing the corresponding element of the pipeline array.  The
 510  * counter in the element should never be greater than 1, otherwise, the
 511  * RCU implementation is broken.
 512  */
 513 static int
 514 rcu_torture_reader(void *arg)
 515 {
 516         int completed;
 517         int idx;
 518         DEFINE_RCU_RANDOM(rand);
 519         struct rcu_torture *p;
 520         int pipe_count;
 521
 522         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
 523         set_user_nice(current, 19);
 524
 525         do {
 526                 idx = cur_ops->readlock();
 527                 completed = cur_ops->completed();
 528                 p = rcu_dereference(rcu_torture_current);
 529                 if (p == NULL) {
 530                         /* Wait for rcu_torture_writer to get underway */
 531                         cur_ops->readunlock(idx);
 532                         schedule_timeout_interruptible(HZ);
 533                         continue;
 534                 }
 535                 if (p->rtort_mbtest == 0)
 536                         atomic_inc(&n_rcu_torture_mberror);
 537                 cur_ops->readdelay(&rand);
 538                 preempt_disable();
 539                 pipe_count = p->rtort_pipe_count;
 540                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
 541                         /* Should not happen, but... */
 542                         pipe_count = RCU_TORTURE_PIPE_LEN;
 543                 }
 544                 ++__get_cpu_var(rcu_torture_count)[pipe_count];
 545                 completed = cur_ops->completed() - completed;
 546                 if (completed > RCU_TORTURE_PIPE_LEN) {
 547                         /* Should not happen, but... */
 548                         completed = RCU_TORTURE_PIPE_LEN;
 549                 }
 550                 ++__get_cpu_var(rcu_torture_batch)[completed];
 551                 preempt_enable();
 552                 cur_ops->readunlock(idx);
 553                 schedule();
 554         } while (!kthread_should_stop() && !fullstop);
 555         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
 556         while (!kthread_should_stop())
 557                 schedule_timeout_uninterruptible(1);
 558         return 0;
 559 }
 560
 561 /*
 562  * Create an RCU-torture statistics message in the specified buffer.
 563  */
 564 static int
 565 rcu_torture_printk(char *page)
 566 {
 567         int cnt = 0;
 568         int cpu;
 569         int i;
 570         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
 571         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
 572
 573         for_each_possible_cpu(cpu) {
 574                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
 575                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
 576                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
 577                 }
 578         }
 579         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
 580                 if (pipesummary[i] != 0)
 581                         break;
 582         }
 583         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
 584         cnt += sprintf(&page[cnt],
 585                        "rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d "
 586                        "rtmbe: %d",
 587                        rcu_torture_current,
 588                        rcu_torture_current_version,
 589                        list_empty(&rcu_torture_freelist),
 590                        atomic_read(&n_rcu_torture_alloc),
 591                        atomic_read(&n_rcu_torture_alloc_fail),
 592                        atomic_read(&n_rcu_torture_free),
 593                        atomic_read(&n_rcu_torture_mberror));
 594         if (atomic_read(&n_rcu_torture_mberror) != 0)
 595                 cnt += sprintf(&page[cnt], " !!!");
 596         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
 597         if (i > 1) {
 598                 cnt += sprintf(&page[cnt], "!!! ");
 599                 atomic_inc(&n_rcu_torture_error);
 600         }
 601         cnt += sprintf(&page[cnt], "Reader Pipe: ");
 602         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
 603                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
 604         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
 605         cnt += sprintf(&page[cnt], "Reader Batch: ");
 606         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
 607                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
 608         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
 609         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
 610         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
 611                 cnt += sprintf(&page[cnt], " %d",
 612                                atomic_read(&rcu_torture_wcount[i]));
 613         }
 614         cnt += sprintf(&page[cnt], "\n");
 615         if (cur_ops->stats != NULL)
 616                 cnt += cur_ops->stats(&page[cnt]);
 617         return cnt;
 618 }
 619
 620 /*
 621  * Print torture statistics.  Caller must ensure that there is only
 622  * one call to this function at a given time!!!  This is normally
 623  * accomplished by relying on the module system to only have one copy
 624  * of the module loaded, and then by giving the rcu_torture_stats
 625  * kthread full control (or the init/cleanup functions when rcu_torture_stats
 626  * thread is not running).
 627  */
 628 static void
 629 rcu_torture_stats_print(void)
 630 {
 631         int cnt;
 632
 633         cnt = rcu_torture_printk(printk_buf);
 634         printk(KERN_ALERT "%s", printk_buf);
 635 }
 636
 637 /*
 638  * Periodically prints torture statistics, if periodic statistics printing
 639  * was specified via the stat_interval module parameter.
 640  *
 641  * No need to worry about fullstop here, since this one doesn't reference
 642  * volatile state or register callbacks.
 643  */
 644 static int
 645 rcu_torture_stats(void *arg)
 646 {
 647         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
 648         do {
 649                 schedule_timeout_interruptible(stat_interval * HZ);
 650                 rcu_torture_stats_print();
 651         } while (!kthread_should_stop());
 652         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
 653         return 0;
 654 }
 655
 656 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
 657
 658 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
 659  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
 660  */
 661 static void rcu_torture_shuffle_tasks(void)
 662 {
 663         cpumask_t tmp_mask = CPU_MASK_ALL;
 664         int i;
 665
 666         lock_cpu_hotplug();
 667
 668         /* No point in shuffling if there is only one online CPU (ex: UP) */
 669         if (num_online_cpus() == 1) {
 670                 unlock_cpu_hotplug();
 671                 return;
 672         }
 673
 674         if (rcu_idle_cpu != -1)
 675                 cpu_clear(rcu_idle_cpu, tmp_mask);
 676
 677         set_cpus_allowed(current, tmp_mask);
 678
 679         if (reader_tasks != NULL) {
 680                 for (i = 0; i < nrealreaders; i++)
 681                         if (reader_tasks[i])
 682                                 set_cpus_allowed(reader_tasks[i], tmp_mask);
 683         }
 684
 685         if (fakewriter_tasks != NULL) {
 686                 for (i = 0; i < nfakewriters; i++)
 687                         if (fakewriter_tasks[i])
 688                                 set_cpus_allowed(fakewriter_tasks[i], tmp_mask);
 689         }
 690
 691         if (writer_task)
 692                 set_cpus_allowed(writer_task, tmp_mask);
 693
 694         if (stats_task)
 695                 set_cpus_allowed(stats_task, tmp_mask);
 696
 697         if (rcu_idle_cpu == -1)
 698                 rcu_idle_cpu = num_online_cpus() - 1;
 699         else
 700                 rcu_idle_cpu--;
 701
 702         unlock_cpu_hotplug();
 703 }
 704
 705 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
 706  * system to become idle at a time and cut off its timer ticks. This is meant
 707  * to test the support for such tickless idle CPU in RCU.
 708  */
 709 static int
 710 rcu_torture_shuffle(void *arg)
 711 {
 712         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
 713         do {
 714                 schedule_timeout_interruptible(shuffle_interval * HZ);
 715                 rcu_torture_shuffle_tasks();
 716         } while (!kthread_should_stop());
 717         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
 718         return 0;
 719 }
 720
 721 static inline void
 722 rcu_torture_print_module_parms(char *tag)
 723 {
 724         printk(KERN_ALERT "%s" TORTURE_FLAG
 725                 "--- %s: nreaders=%d nfakewriters=%d "
 726                 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
 727                 "shuffle_interval = %d\n",
 728                 torture_type, tag, nrealreaders, nfakewriters,
 729                 stat_interval, verbose, test_no_idle_hz, shuffle_interval);
 730 }
 731
 732 static void
 733 rcu_torture_cleanup(void)
 734 {
 735         int i;
 736
 737         fullstop = 1;
 738         if (shuffler_task != NULL) {
 739                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
 740                 kthread_stop(shuffler_task);
 741         }
 742         shuffler_task = NULL;
 743
 744         if (writer_task != NULL) {
 745                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
 746                 kthread_stop(writer_task);
 747         }
 748         writer_task = NULL;
 749
 750         if (reader_tasks != NULL) {
 751                 for (i = 0; i < nrealreaders; i++) {
 752                         if (reader_tasks[i] != NULL) {
 753                                 VERBOSE_PRINTK_STRING(
 754                                         "Stopping rcu_torture_reader task");
 755                                 kthread_stop(reader_tasks[i]);
 756                         }
 757                         reader_tasks[i] = NULL;
 758                 }
 759                 kfree(reader_tasks);
 760                 reader_tasks = NULL;
 761         }
 762         rcu_torture_current = NULL;
 763
 764         if (fakewriter_tasks != NULL) {
 765                 for (i = 0; i < nfakewriters; i++) {
 766                         if (fakewriter_tasks[i] != NULL) {
 767                                 VERBOSE_PRINTK_STRING(
 768                                         "Stopping rcu_torture_fakewriter task");
 769                                 kthread_stop(fakewriter_tasks[i]);
 770                         }
 771                         fakewriter_tasks[i] = NULL;
 772                 }
 773                 kfree(fakewriter_tasks);
 774                 fakewriter_tasks = NULL;
 775         }
 776
 777         if (stats_task != NULL) {
 778                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
 779                 kthread_stop(stats_task);
 780         }
 781         stats_task = NULL;
 782
 783         /* Wait for all RCU callbacks to fire.  */
 784         rcu_barrier();
 785
 786         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
 787
 788         if (cur_ops->cleanup != NULL)
 789                 cur_ops->cleanup();
 790         if (atomic_read(&n_rcu_torture_error))
 791                 rcu_torture_print_module_parms("End of test: FAILURE");
 792         else
 793                 rcu_torture_print_module_parms("End of test: SUCCESS");
 794 }
 795
 796 static int
 797 rcu_torture_init(void)
 798 {
 799         int i;
 800         int cpu;
 801         int firsterr = 0;
 802
 803         /* Process args and tell the world that the torturer is on the job. */
 804
 805         for (i = 0; cur_ops = torture_ops[i], cur_ops != NULL; i++) {
 806                 cur_ops = torture_ops[i];
 807                 if (strcmp(torture_type, cur_ops->name) == 0) {
 808                         break;
 809                 }
 810         }
 811         if (cur_ops == NULL) {
 812                 printk(KERN_ALERT "rcutorture: invalid torture type: \"%s\"\n",
 813                        torture_type);
 814                 return (-EINVAL);
 815         }
 816         if (cur_ops->init != NULL)
 817                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
 818
 819         if (nreaders >= 0)
 820                 nrealreaders = nreaders;
 821         else
 822                 nrealreaders = 2 * num_online_cpus();
 823         rcu_torture_print_module_parms("Start of test");
 824         fullstop = 0;
 825
 826         /* Set up the freelist. */
 827
 828         INIT_LIST_HEAD(&rcu_torture_freelist);
 829         for (i = 0; i < sizeof(rcu_tortures) / sizeof(rcu_tortures[0]); i++) {
 830                 rcu_tortures[i].rtort_mbtest = 0;
 831                 list_add_tail(&rcu_tortures[i].rtort_free,
 832                               &rcu_torture_freelist);
 833         }
 834
 835         /* Initialize the statistics so that each run gets its own numbers. */
 836
 837         rcu_torture_current = NULL;
 838         rcu_torture_current_version = 0;
 839         atomic_set(&n_rcu_torture_alloc, 0);
 840         atomic_set(&n_rcu_torture_alloc_fail, 0);
 841         atomic_set(&n_rcu_torture_free, 0);
 842         atomic_set(&n_rcu_torture_mberror, 0);
 843         atomic_set(&n_rcu_torture_error, 0);
 844         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
 845                 atomic_set(&rcu_torture_wcount[i], 0);
 846         for_each_possible_cpu(cpu) {
 847                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
 848                         per_cpu(rcu_torture_count, cpu)[i] = 0;
 849                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
 850                 }
 851         }
 852
 853         /* Start up the kthreads. */
 854
 855         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
 856         writer_task = kthread_run(rcu_torture_writer, NULL,
 857                                   "rcu_torture_writer");
 858         if (IS_ERR(writer_task)) {
 859                 firsterr = PTR_ERR(writer_task);
 860                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
 861                 writer_task = NULL;
 862                 goto unwind;
 863         }
 864         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
 865                                    GFP_KERNEL);
 866         if (fakewriter_tasks == NULL) {
 867                 VERBOSE_PRINTK_ERRSTRING("out of memory");
 868                 firsterr = -ENOMEM;
 869                 goto unwind;
 870         }
 871         for (i = 0; i < nfakewriters; i++) {
 872                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
 873                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
 874                                                   "rcu_torture_fakewriter");
 875                 if (IS_ERR(fakewriter_tasks[i])) {
 876                         firsterr = PTR_ERR(fakewriter_tasks[i]);
 877                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
 878                         fakewriter_tasks[i] = NULL;
 879                         goto unwind;
 880                 }
 881         }
 882         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
 883                                GFP_KERNEL);
 884         if (reader_tasks == NULL) {
 885                 VERBOSE_PRINTK_ERRSTRING("out of memory");
 886                 firsterr = -ENOMEM;
 887                 goto unwind;
 888         }
 889         for (i = 0; i < nrealreaders; i++) {
 890                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
 891                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
 892                                               "rcu_torture_reader");
 893                 if (IS_ERR(reader_tasks[i])) {
 894                         firsterr = PTR_ERR(reader_tasks[i]);
 895                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
 896                         reader_tasks[i] = NULL;
 897                         goto unwind;
 898                 }
 899         }
 900         if (stat_interval > 0) {
 901                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
 902                 stats_task = kthread_run(rcu_torture_stats, NULL,
 903                                         "rcu_torture_stats");
 904                 if (IS_ERR(stats_task)) {
 905                         firsterr = PTR_ERR(stats_task);
 906                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
 907                         stats_task = NULL;
 908                         goto unwind;
 909                 }
 910         }
 911         if (test_no_idle_hz) {
 912                 rcu_idle_cpu = num_online_cpus() - 1;
 913                 /* Create the shuffler thread */
 914                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
 915                                           "rcu_torture_shuffle");
 916                 if (IS_ERR(shuffler_task)) {
 917                         firsterr = PTR_ERR(shuffler_task);
 918                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
 919                         shuffler_task = NULL;
 920                         goto unwind;
 921                 }
 922         }
 923         return 0;
 924
 925 unwind:
 926         rcu_torture_cleanup();
 927         return firsterr;
 928 }
 929
 930 module_init(rcu_torture_init);
 931 module_exit(rcu_torture_cleanup);