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