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   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 static struct list_head rcu_torture_removed;
 121
 122 /*
 123  * Allocate an element from the rcu_tortures pool.
 124  */
 125 static struct rcu_torture *
 126 rcu_torture_alloc(void)
 127 {
 128         struct list_head *p;
 129
 130         spin_lock_bh(&rcu_torture_lock);
 131         if (list_empty(&rcu_torture_freelist)) {
 132                 atomic_inc(&n_rcu_torture_alloc_fail);
 133                 spin_unlock_bh(&rcu_torture_lock);
 134                 return NULL;
 135         }
 136         atomic_inc(&n_rcu_torture_alloc);
 137         p = rcu_torture_freelist.next;
 138         list_del_init(p);
 139         spin_unlock_bh(&rcu_torture_lock);
 140         return container_of(p, struct rcu_torture, rtort_free);
 141 }
 142
 143 /*
 144  * Free an element to the rcu_tortures pool.
 145  */
 146 static void
 147 rcu_torture_free(struct rcu_torture *p)
 148 {
 149         atomic_inc(&n_rcu_torture_free);
 150         spin_lock_bh(&rcu_torture_lock);
 151         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 152         spin_unlock_bh(&rcu_torture_lock);
 153 }
 154
 155 struct rcu_random_state {
 156         unsigned long rrs_state;
 157         long rrs_count;
 158 };
 159
 160 #define RCU_RANDOM_MULT 39916801  /* prime */
 161 #define RCU_RANDOM_ADD  479001701 /* prime */
 162 #define RCU_RANDOM_REFRESH 10000
 163
 164 #define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
 165
 166 /*
 167  * Crude but fast random-number generator.  Uses a linear congruential
 168  * generator, with occasional help from get_random_bytes().
 169  */
 170 static unsigned long
 171 rcu_random(struct rcu_random_state *rrsp)
 172 {
 173         long refresh;
 174
 175         if (--rrsp->rrs_count < 0) {
 176                 get_random_bytes(&refresh, sizeof(refresh));
 177                 rrsp->rrs_state += refresh;
 178                 rrsp->rrs_count = RCU_RANDOM_REFRESH;
 179         }
 180         rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
 181         return swahw32(rrsp->rrs_state);
 182 }
 183
 184 /*
 185  * Operations vector for selecting different types of tests.
 186  */
 187
 188 struct rcu_torture_ops {
 189         void (*init)(void);
 190         void (*cleanup)(void);
 191         int (*readlock)(void);
 192         void (*readdelay)(struct rcu_random_state *rrsp);
 193         void (*readunlock)(int idx);
 194         int (*completed)(void);
 195         void (*deferredfree)(struct rcu_torture *p);
 196         void (*sync)(void);
 197         int (*stats)(char *page);
 198         char *name;
 199 };
 200 static struct rcu_torture_ops *cur_ops = NULL;
 201
 202 /*
 203  * Definitions for rcu torture testing.
 204  */
 205
 206 static int rcu_torture_read_lock(void) __acquires(RCU)
 207 {
 208         rcu_read_lock();
 209         return 0;
 210 }
 211
 212 static void rcu_read_delay(struct rcu_random_state *rrsp)
 213 {
 214         long delay;
 215         const long longdelay = 200;
 216
 217         /* We want there to be long-running readers, but not all the time. */
 218
 219         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay);
 220         if (!delay)
 221                 udelay(longdelay);
 222 }
 223
 224 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 225 {
 226         rcu_read_unlock();
 227 }
 228
 229 static int rcu_torture_completed(void)
 230 {
 231         return rcu_batches_completed();
 232 }
 233
 234 static void
 235 rcu_torture_cb(struct rcu_head *p)
 236 {
 237         int i;
 238         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 239
 240         if (fullstop) {
 241                 /* Test is ending, just drop callbacks on the floor. */
 242                 /* The next initialization will pick up the pieces. */
 243                 return;
 244         }
 245         i = rp->rtort_pipe_count;
 246         if (i > RCU_TORTURE_PIPE_LEN)
 247                 i = RCU_TORTURE_PIPE_LEN;
 248         atomic_inc(&rcu_torture_wcount[i]);
 249         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 250                 rp->rtort_mbtest = 0;
 251                 rcu_torture_free(rp);
 252         } else
 253                 cur_ops->deferredfree(rp);
 254 }
 255
 256 static void rcu_torture_deferred_free(struct rcu_torture *p)
 257 {
 258         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 259 }
 260
 261 static struct rcu_torture_ops rcu_ops = {
 262         .init = NULL,
 263         .cleanup = NULL,
 264         .readlock = rcu_torture_read_lock,
 265         .readdelay = rcu_read_delay,
 266         .readunlock = rcu_torture_read_unlock,
 267         .completed = rcu_torture_completed,
 268         .deferredfree = rcu_torture_deferred_free,
 269         .sync = synchronize_rcu,
 270         .stats = NULL,
 271         .name = "rcu"
 272 };
 273
 274 static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
 275 {
 276         int i;
 277         struct rcu_torture *rp;
 278         struct rcu_torture *rp1;
 279
 280         cur_ops->sync();
 281         list_add(&p->rtort_free, &rcu_torture_removed);
 282         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 283                 i = rp->rtort_pipe_count;
 284                 if (i > RCU_TORTURE_PIPE_LEN)
 285                         i = RCU_TORTURE_PIPE_LEN;
 286                 atomic_inc(&rcu_torture_wcount[i]);
 287                 if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 288                         rp->rtort_mbtest = 0;
 289                         list_del(&rp->rtort_free);
 290                         rcu_torture_free(rp);
 291                 }
 292         }
 293 }
 294
 295 static void rcu_sync_torture_init(void)
 296 {
 297         INIT_LIST_HEAD(&rcu_torture_removed);
 298 }
 299
 300 /*
 301  * Definitions for rcu_bh torture testing.
 302  */
 303
 304 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
 305 {
 306         rcu_read_lock_bh();
 307         return 0;
 308 }
 309
 310 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
 311 {
 312         rcu_read_unlock_bh();
 313 }
 314
 315 static int rcu_bh_torture_completed(void)
 316 {
 317         return rcu_batches_completed_bh();
 318 }
 319
 320 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 321 {
 322         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
 323 }
 324
 325 struct rcu_bh_torture_synchronize {
 326         struct rcu_head head;
 327         struct completion completion;
 328 };
 329
 330 static void rcu_bh_torture_wakeme_after_cb(struct rcu_head *head)
 331 {
 332         struct rcu_bh_torture_synchronize *rcu;
 333
 334         rcu = container_of(head, struct rcu_bh_torture_synchronize, head);
 335         complete(&rcu->completion);
 336 }
 337
 338 static void rcu_bh_torture_synchronize(void)
 339 {
 340         struct rcu_bh_torture_synchronize rcu;
 341
 342         init_completion(&rcu.completion);
 343         call_rcu_bh(&rcu.head, rcu_bh_torture_wakeme_after_cb);
 344         wait_for_completion(&rcu.completion);
 345 }
 346
 347 static struct rcu_torture_ops rcu_bh_ops = {
 348         .init = NULL,
 349         .cleanup = NULL,
 350         .readlock = rcu_bh_torture_read_lock,
 351         .readdelay = rcu_read_delay,  /* just reuse rcu's version. */
 352         .readunlock = rcu_bh_torture_read_unlock,
 353         .completed = rcu_bh_torture_completed,
 354         .deferredfree = rcu_bh_torture_deferred_free,
 355         .sync = rcu_bh_torture_synchronize,
 356         .stats = NULL,
 357         .name = "rcu_bh"
 358 };
 359
 360 /*
 361  * Definitions for srcu torture testing.
 362  */
 363
 364 static struct srcu_struct srcu_ctl;
 365
 366 static void srcu_torture_init(void)
 367 {
 368         init_srcu_struct(&srcu_ctl);
 369         rcu_sync_torture_init();
 370 }
 371
 372 static void srcu_torture_cleanup(void)
 373 {
 374         synchronize_srcu(&srcu_ctl);
 375         cleanup_srcu_struct(&srcu_ctl);
 376 }
 377
 378 static int srcu_torture_read_lock(void)
 379 {
 380         return srcu_read_lock(&srcu_ctl);
 381 }
 382
 383 static void srcu_read_delay(struct rcu_random_state *rrsp)
 384 {
 385         long delay;
 386         const long uspertick = 1000000 / HZ;
 387         const long longdelay = 10;
 388
 389         /* We want there to be long-running readers, but not all the time. */
 390
 391         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
 392         if (!delay)
 393                 schedule_timeout_interruptible(longdelay);
 394 }
 395
 396 static void srcu_torture_read_unlock(int idx)
 397 {
 398         srcu_read_unlock(&srcu_ctl, idx);
 399 }
 400
 401 static int srcu_torture_completed(void)
 402 {
 403         return srcu_batches_completed(&srcu_ctl);
 404 }
 405
 406 static void srcu_torture_synchronize(void)
 407 {
 408         synchronize_srcu(&srcu_ctl);
 409 }
 410
 411 static int srcu_torture_stats(char *page)
 412 {
 413         int cnt = 0;
 414         int cpu;
 415         int idx = srcu_ctl.completed & 0x1;
 416
 417         cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
 418                        torture_type, TORTURE_FLAG, idx);
 419         for_each_possible_cpu(cpu) {
 420                 cnt += sprintf(&page[cnt], " %d(%d,%d)", cpu,
 421                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
 422                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
 423         }
 424         cnt += sprintf(&page[cnt], "\n");
 425         return cnt;
 426 }
 427
 428 static struct rcu_torture_ops srcu_ops = {
 429         .init = srcu_torture_init,
 430         .cleanup = srcu_torture_cleanup,
 431         .readlock = srcu_torture_read_lock,
 432         .readdelay = srcu_read_delay,
 433         .readunlock = srcu_torture_read_unlock,
 434         .completed = srcu_torture_completed,
 435         .deferredfree = rcu_sync_torture_deferred_free,
 436         .sync = srcu_torture_synchronize,
 437         .stats = srcu_torture_stats,
 438         .name = "srcu"
 439 };
 440
 441 static struct rcu_torture_ops *torture_ops[] =
 442         { &rcu_ops, &rcu_bh_ops, &srcu_ops, NULL };
 443
 444 /*
 445  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 446  * for that pointed to by rcu_torture_current, freeing the old structure
 447  * after a series of grace periods (the "pipeline").
 448  */
 449 static int
 450 rcu_torture_writer(void *arg)
 451 {
 452         int i;
 453         long oldbatch = rcu_batches_completed();
 454         struct rcu_torture *rp;
 455         struct rcu_torture *old_rp;
 456         static DEFINE_RCU_RANDOM(rand);
 457
 458         VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
 459         set_user_nice(current, 19);
 460
 461         do {
 462                 schedule_timeout_uninterruptible(1);
 463                 if ((rp = rcu_torture_alloc()) == NULL)
 464                         continue;
 465                 rp->rtort_pipe_count = 0;
 466                 udelay(rcu_random(&rand) & 0x3ff);
 467                 old_rp = rcu_torture_current;
 468                 rp->rtort_mbtest = 1;
 469                 rcu_assign_pointer(rcu_torture_current, rp);
 470                 smp_wmb();
 471                 if (old_rp != NULL) {
 472                         i = old_rp->rtort_pipe_count;
 473                         if (i > RCU_TORTURE_PIPE_LEN)
 474                                 i = RCU_TORTURE_PIPE_LEN;
 475                         atomic_inc(&rcu_torture_wcount[i]);
 476                         old_rp->rtort_pipe_count++;
 477                         cur_ops->deferredfree(old_rp);
 478                 }
 479                 rcu_torture_current_version++;
 480                 oldbatch = cur_ops->completed();
 481         } while (!kthread_should_stop() && !fullstop);
 482         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
 483         while (!kthread_should_stop())
 484                 schedule_timeout_uninterruptible(1);
 485         return 0;
 486 }
 487
 488 /*
 489  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
 490  * delay between calls.
 491  */
 492 static int
 493 rcu_torture_fakewriter(void *arg)
 494 {
 495         DEFINE_RCU_RANDOM(rand);
 496
 497         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
 498         set_user_nice(current, 19);
 499
 500         do {
 501                 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
 502                 udelay(rcu_random(&rand) & 0x3ff);
 503                 cur_ops->sync();
 504         } while (!kthread_should_stop() && !fullstop);
 505
 506         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
 507         while (!kthread_should_stop())
 508                 schedule_timeout_uninterruptible(1);
 509         return 0;
 510 }
 511
 512 /*
 513  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
 514  * incrementing the corresponding element of the pipeline array.  The
 515  * counter in the element should never be greater than 1, otherwise, the
 516  * RCU implementation is broken.
 517  */
 518 static int
 519 rcu_torture_reader(void *arg)
 520 {
 521         int completed;
 522         int idx;
 523         DEFINE_RCU_RANDOM(rand);
 524         struct rcu_torture *p;
 525         int pipe_count;
 526
 527         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
 528         set_user_nice(current, 19);
 529
 530         do {
 531                 idx = cur_ops->readlock();
 532                 completed = cur_ops->completed();
 533                 p = rcu_dereference(rcu_torture_current);
 534                 if (p == NULL) {
 535                         /* Wait for rcu_torture_writer to get underway */
 536                         cur_ops->readunlock(idx);
 537                         schedule_timeout_interruptible(HZ);
 538                         continue;
 539                 }
 540                 if (p->rtort_mbtest == 0)
 541                         atomic_inc(&n_rcu_torture_mberror);
 542                 cur_ops->readdelay(&rand);
 543                 preempt_disable();
 544                 pipe_count = p->rtort_pipe_count;
 545                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
 546                         /* Should not happen, but... */
 547                         pipe_count = RCU_TORTURE_PIPE_LEN;
 548                 }
 549                 ++__get_cpu_var(rcu_torture_count)[pipe_count];
 550                 completed = cur_ops->completed() - completed;
 551                 if (completed > RCU_TORTURE_PIPE_LEN) {
 552                         /* Should not happen, but... */
 553                         completed = RCU_TORTURE_PIPE_LEN;
 554                 }
 555                 ++__get_cpu_var(rcu_torture_batch)[completed];
 556                 preempt_enable();
 557                 cur_ops->readunlock(idx);
 558                 schedule();
 559         } while (!kthread_should_stop() && !fullstop);
 560         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
 561         while (!kthread_should_stop())
 562                 schedule_timeout_uninterruptible(1);
 563         return 0;
 564 }
 565
 566 /*
 567  * Create an RCU-torture statistics message in the specified buffer.
 568  */
 569 static int
 570 rcu_torture_printk(char *page)
 571 {
 572         int cnt = 0;
 573         int cpu;
 574         int i;
 575         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
 576         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
 577
 578         for_each_possible_cpu(cpu) {
 579                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
 580                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
 581                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
 582                 }
 583         }
 584         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
 585                 if (pipesummary[i] != 0)
 586                         break;
 587         }
 588         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
 589         cnt += sprintf(&page[cnt],
 590                        "rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d "
 591                        "rtmbe: %d",
 592                        rcu_torture_current,
 593                        rcu_torture_current_version,
 594                        list_empty(&rcu_torture_freelist),
 595                        atomic_read(&n_rcu_torture_alloc),
 596                        atomic_read(&n_rcu_torture_alloc_fail),
 597                        atomic_read(&n_rcu_torture_free),
 598                        atomic_read(&n_rcu_torture_mberror));
 599         if (atomic_read(&n_rcu_torture_mberror) != 0)
 600                 cnt += sprintf(&page[cnt], " !!!");
 601         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
 602         if (i > 1) {
 603                 cnt += sprintf(&page[cnt], "!!! ");
 604                 atomic_inc(&n_rcu_torture_error);
 605         }
 606         cnt += sprintf(&page[cnt], "Reader Pipe: ");
 607         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
 608                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
 609         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
 610         cnt += sprintf(&page[cnt], "Reader Batch: ");
 611         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
 612                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
 613         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
 614         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
 615         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
 616                 cnt += sprintf(&page[cnt], " %d",
 617                                atomic_read(&rcu_torture_wcount[i]));
 618         }
 619         cnt += sprintf(&page[cnt], "\n");
 620         if (cur_ops->stats != NULL)
 621                 cnt += cur_ops->stats(&page[cnt]);
 622         return cnt;
 623 }
 624
 625 /*
 626  * Print torture statistics.  Caller must ensure that there is only
 627  * one call to this function at a given time!!!  This is normally
 628  * accomplished by relying on the module system to only have one copy
 629  * of the module loaded, and then by giving the rcu_torture_stats
 630  * kthread full control (or the init/cleanup functions when rcu_torture_stats
 631  * thread is not running).
 632  */
 633 static void
 634 rcu_torture_stats_print(void)
 635 {
 636         int cnt;
 637
 638         cnt = rcu_torture_printk(printk_buf);
 639         printk(KERN_ALERT "%s", printk_buf);
 640 }
 641
 642 /*
 643  * Periodically prints torture statistics, if periodic statistics printing
 644  * was specified via the stat_interval module parameter.
 645  *
 646  * No need to worry about fullstop here, since this one doesn't reference
 647  * volatile state or register callbacks.
 648  */
 649 static int
 650 rcu_torture_stats(void *arg)
 651 {
 652         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
 653         do {
 654                 schedule_timeout_interruptible(stat_interval * HZ);
 655                 rcu_torture_stats_print();
 656         } while (!kthread_should_stop());
 657         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
 658         return 0;
 659 }
 660
 661 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
 662
 663 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
 664  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
 665  */
 666 static void rcu_torture_shuffle_tasks(void)
 667 {
 668         cpumask_t tmp_mask = CPU_MASK_ALL;
 669         int i;
 670
 671         lock_cpu_hotplug();
 672
 673         /* No point in shuffling if there is only one online CPU (ex: UP) */
 674         if (num_online_cpus() == 1) {
 675                 unlock_cpu_hotplug();
 676                 return;
 677         }
 678
 679         if (rcu_idle_cpu != -1)
 680                 cpu_clear(rcu_idle_cpu, tmp_mask);
 681
 682         set_cpus_allowed(current, tmp_mask);
 683
 684         if (reader_tasks != NULL) {
 685                 for (i = 0; i < nrealreaders; i++)
 686                         if (reader_tasks[i])
 687                                 set_cpus_allowed(reader_tasks[i], tmp_mask);
 688         }
 689
 690         if (fakewriter_tasks != NULL) {
 691                 for (i = 0; i < nfakewriters; i++)
 692                         if (fakewriter_tasks[i])
 693                                 set_cpus_allowed(fakewriter_tasks[i], tmp_mask);
 694         }
 695
 696         if (writer_task)
 697                 set_cpus_allowed(writer_task, tmp_mask);
 698
 699         if (stats_task)
 700                 set_cpus_allowed(stats_task, tmp_mask);
 701
 702         if (rcu_idle_cpu == -1)
 703                 rcu_idle_cpu = num_online_cpus() - 1;
 704         else
 705                 rcu_idle_cpu--;
 706
 707         unlock_cpu_hotplug();
 708 }
 709
 710 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
 711  * system to become idle at a time and cut off its timer ticks. This is meant
 712  * to test the support for such tickless idle CPU in RCU.
 713  */
 714 static int
 715 rcu_torture_shuffle(void *arg)
 716 {
 717         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
 718         do {
 719                 schedule_timeout_interruptible(shuffle_interval * HZ);
 720                 rcu_torture_shuffle_tasks();
 721         } while (!kthread_should_stop());
 722         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
 723         return 0;
 724 }
 725
 726 static inline void
 727 rcu_torture_print_module_parms(char *tag)
 728 {
 729         printk(KERN_ALERT "%s" TORTURE_FLAG
 730                 "--- %s: nreaders=%d nfakewriters=%d "
 731                 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
 732                 "shuffle_interval = %d\n",
 733                 torture_type, tag, nrealreaders, nfakewriters,
 734                 stat_interval, verbose, test_no_idle_hz, shuffle_interval);
 735 }
 736
 737 static void
 738 rcu_torture_cleanup(void)
 739 {
 740         int i;
 741
 742         fullstop = 1;
 743         if (shuffler_task != NULL) {
 744                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
 745                 kthread_stop(shuffler_task);
 746         }
 747         shuffler_task = NULL;
 748
 749         if (writer_task != NULL) {
 750                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
 751                 kthread_stop(writer_task);
 752         }
 753         writer_task = NULL;
 754
 755         if (reader_tasks != NULL) {
 756                 for (i = 0; i < nrealreaders; i++) {
 757                         if (reader_tasks[i] != NULL) {
 758                                 VERBOSE_PRINTK_STRING(
 759                                         "Stopping rcu_torture_reader task");
 760                                 kthread_stop(reader_tasks[i]);
 761                         }
 762                         reader_tasks[i] = NULL;
 763                 }
 764                 kfree(reader_tasks);
 765                 reader_tasks = NULL;
 766         }
 767         rcu_torture_current = NULL;
 768
 769         if (fakewriter_tasks != NULL) {
 770                 for (i = 0; i < nfakewriters; i++) {
 771                         if (fakewriter_tasks[i] != NULL) {
 772                                 VERBOSE_PRINTK_STRING(
 773                                         "Stopping rcu_torture_fakewriter task");
 774                                 kthread_stop(fakewriter_tasks[i]);
 775                         }
 776                         fakewriter_tasks[i] = NULL;
 777                 }
 778                 kfree(fakewriter_tasks);
 779                 fakewriter_tasks = NULL;
 780         }
 781
 782         if (stats_task != NULL) {
 783                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
 784                 kthread_stop(stats_task);
 785         }
 786         stats_task = NULL;
 787
 788         /* Wait for all RCU callbacks to fire.  */
 789         rcu_barrier();
 790
 791         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
 792
 793         if (cur_ops->cleanup != NULL)
 794                 cur_ops->cleanup();
 795         if (atomic_read(&n_rcu_torture_error))
 796                 rcu_torture_print_module_parms("End of test: FAILURE");
 797         else
 798                 rcu_torture_print_module_parms("End of test: SUCCESS");
 799 }
 800
 801 static int
 802 rcu_torture_init(void)
 803 {
 804         int i;
 805         int cpu;
 806         int firsterr = 0;
 807
 808         /* Process args and tell the world that the torturer is on the job. */
 809
 810         for (i = 0; cur_ops = torture_ops[i], cur_ops != NULL; i++) {
 811                 cur_ops = torture_ops[i];
 812                 if (strcmp(torture_type, cur_ops->name) == 0) {
 813                         break;
 814                 }
 815         }
 816         if (cur_ops == NULL) {
 817                 printk(KERN_ALERT "rcutorture: invalid torture type: \"%s\"\n",
 818                        torture_type);
 819                 return (-EINVAL);
 820         }
 821         if (cur_ops->init != NULL)
 822                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
 823
 824         if (nreaders >= 0)
 825                 nrealreaders = nreaders;
 826         else
 827                 nrealreaders = 2 * num_online_cpus();
 828         rcu_torture_print_module_parms("Start of test");
 829         fullstop = 0;
 830
 831         /* Set up the freelist. */
 832
 833         INIT_LIST_HEAD(&rcu_torture_freelist);
 834         for (i = 0; i < sizeof(rcu_tortures) / sizeof(rcu_tortures[0]); i++) {
 835                 rcu_tortures[i].rtort_mbtest = 0;
 836                 list_add_tail(&rcu_tortures[i].rtort_free,
 837                               &rcu_torture_freelist);
 838         }
 839
 840         /* Initialize the statistics so that each run gets its own numbers. */
 841
 842         rcu_torture_current = NULL;
 843         rcu_torture_current_version = 0;
 844         atomic_set(&n_rcu_torture_alloc, 0);
 845         atomic_set(&n_rcu_torture_alloc_fail, 0);
 846         atomic_set(&n_rcu_torture_free, 0);
 847         atomic_set(&n_rcu_torture_mberror, 0);
 848         atomic_set(&n_rcu_torture_error, 0);
 849         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
 850                 atomic_set(&rcu_torture_wcount[i], 0);
 851         for_each_possible_cpu(cpu) {
 852                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
 853                         per_cpu(rcu_torture_count, cpu)[i] = 0;
 854                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
 855                 }
 856         }
 857
 858         /* Start up the kthreads. */
 859
 860         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
 861         writer_task = kthread_run(rcu_torture_writer, NULL,
 862                                   "rcu_torture_writer");
 863         if (IS_ERR(writer_task)) {
 864                 firsterr = PTR_ERR(writer_task);
 865                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
 866                 writer_task = NULL;
 867                 goto unwind;
 868         }
 869         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
 870                                    GFP_KERNEL);
 871         if (fakewriter_tasks == NULL) {
 872                 VERBOSE_PRINTK_ERRSTRING("out of memory");
 873                 firsterr = -ENOMEM;
 874                 goto unwind;
 875         }
 876         for (i = 0; i < nfakewriters; i++) {
 877                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
 878                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
 879                                                   "rcu_torture_fakewriter");
 880                 if (IS_ERR(fakewriter_tasks[i])) {
 881                         firsterr = PTR_ERR(fakewriter_tasks[i]);
 882                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
 883                         fakewriter_tasks[i] = NULL;
 884                         goto unwind;
 885                 }
 886         }
 887         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
 888                                GFP_KERNEL);
 889         if (reader_tasks == NULL) {
 890                 VERBOSE_PRINTK_ERRSTRING("out of memory");
 891                 firsterr = -ENOMEM;
 892                 goto unwind;
 893         }
 894         for (i = 0; i < nrealreaders; i++) {
 895                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
 896                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
 897                                               "rcu_torture_reader");
 898                 if (IS_ERR(reader_tasks[i])) {
 899                         firsterr = PTR_ERR(reader_tasks[i]);
 900                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
 901                         reader_tasks[i] = NULL;
 902                         goto unwind;
 903                 }
 904         }
 905         if (stat_interval > 0) {
 906                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
 907                 stats_task = kthread_run(rcu_torture_stats, NULL,
 908                                         "rcu_torture_stats");
 909                 if (IS_ERR(stats_task)) {
 910                         firsterr = PTR_ERR(stats_task);
 911                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
 912                         stats_task = NULL;
 913                         goto unwind;
 914                 }
 915         }
 916         if (test_no_idle_hz) {
 917                 rcu_idle_cpu = num_online_cpus() - 1;
 918                 /* Create the shuffler thread */
 919                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
 920                                           "rcu_torture_shuffle");
 921                 if (IS_ERR(shuffler_task)) {
 922                         firsterr = PTR_ERR(shuffler_task);
 923                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
 924                         shuffler_task = NULL;
 925                         goto unwind;
 926                 }
 927         }
 928         return 0;
 929
 930 unwind:
 931         rcu_torture_cleanup();
 932         return firsterr;
 933 }
 934
 935 module_init(rcu_torture_init);
 936 module_exit(rcu_torture_cleanup);