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