Root/kernel/rcutorture.c

1/*
2 * Read-Copy Update module-based torture test facility
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
17 *
18 * Copyright (C) IBM Corporation, 2005, 2006
19 *
20 * Authors: Paul E. McKenney <paulmck@us.ibm.com>
21 * Josh Triplett <josh@freedesktop.org>
22 *
23 * See also: Documentation/RCU/torture.txt
24 */
25#include <linux/types.h>
26#include <linux/kernel.h>
27#include <linux/init.h>
28#include <linux/module.h>
29#include <linux/kthread.h>
30#include <linux/err.h>
31#include <linux/spinlock.h>
32#include <linux/smp.h>
33#include <linux/rcupdate.h>
34#include <linux/interrupt.h>
35#include <linux/sched.h>
36#include <linux/atomic.h>
37#include <linux/bitops.h>
38#include <linux/completion.h>
39#include <linux/moduleparam.h>
40#include <linux/percpu.h>
41#include <linux/notifier.h>
42#include <linux/reboot.h>
43#include <linux/freezer.h>
44#include <linux/cpu.h>
45#include <linux/delay.h>
46#include <linux/stat.h>
47#include <linux/srcu.h>
48#include <linux/slab.h>
49#include <asm/byteorder.h>
50
51MODULE_LICENSE("GPL");
52MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and "
53          "Josh Triplett <josh@freedesktop.org>");
54
55static int nreaders = -1; /* # reader threads, defaults to 2*ncpus */
56static int nfakewriters = 4; /* # fake writer threads */
57static int stat_interval; /* Interval between stats, in seconds. */
58                /* Defaults to "only at end of test". */
59static bool verbose; /* Print more debug info. */
60static bool test_no_idle_hz; /* Test RCU's 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 { printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
124#define VERBOSE_PRINTK_STRING(s) \
125    do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
126#define VERBOSE_PRINTK_ERRSTRING(s) \
127    do { if (verbose) printk(KERN_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 long n_online_attempts;
181static long n_online_successes;
182static long n_barrier_attempts;
183static long n_barrier_successes;
184static struct list_head rcu_torture_removed;
185static cpumask_var_t shuffle_tmp_mask;
186
187static int stutter_pause_test;
188
189#if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
190#define RCUTORTURE_RUNNABLE_INIT 1
191#else
192#define RCUTORTURE_RUNNABLE_INIT 0
193#endif
194int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT;
195module_param(rcutorture_runnable, int, 0444);
196MODULE_PARM_DESC(rcutorture_runnable, "Start rcutorture at boot");
197
198#if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
199#define rcu_can_boost() 1
200#else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
201#define rcu_can_boost() 0
202#endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
203
204static unsigned long shutdown_time; /* jiffies to system shutdown. */
205static unsigned long boost_starttime; /* jiffies of next boost test start. */
206DEFINE_MUTEX(boost_mutex); /* protect setting boost_starttime */
207                    /* and boost task create/destroy. */
208static atomic_t barrier_cbs_count; /* Barrier callbacks registered. */
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
414static int rcu_no_completed(void)
415{
416    return 0;
417}
418
419static void rcu_torture_deferred_free(struct rcu_torture *p)
420{
421    call_rcu(&p->rtort_rcu, rcu_torture_cb);
422}
423
424static struct rcu_torture_ops rcu_ops = {
425    .init = NULL,
426    .cleanup = NULL,
427    .readlock = rcu_torture_read_lock,
428    .read_delay = rcu_read_delay,
429    .readunlock = rcu_torture_read_unlock,
430    .completed = rcu_torture_completed,
431    .deferred_free = rcu_torture_deferred_free,
432    .sync = synchronize_rcu,
433    .call = call_rcu,
434    .cb_barrier = rcu_barrier,
435    .fqs = rcu_force_quiescent_state,
436    .stats = NULL,
437    .irq_capable = 1,
438    .can_boost = rcu_can_boost(),
439    .name = "rcu"
440};
441
442static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
443{
444    int i;
445    struct rcu_torture *rp;
446    struct rcu_torture *rp1;
447
448    cur_ops->sync();
449    list_add(&p->rtort_free, &rcu_torture_removed);
450    list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
451        i = rp->rtort_pipe_count;
452        if (i > RCU_TORTURE_PIPE_LEN)
453            i = RCU_TORTURE_PIPE_LEN;
454        atomic_inc(&rcu_torture_wcount[i]);
455        if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
456            rp->rtort_mbtest = 0;
457            list_del(&rp->rtort_free);
458            rcu_torture_free(rp);
459        }
460    }
461}
462
463static void rcu_sync_torture_init(void)
464{
465    INIT_LIST_HEAD(&rcu_torture_removed);
466}
467
468static struct rcu_torture_ops rcu_sync_ops = {
469    .init = rcu_sync_torture_init,
470    .cleanup = NULL,
471    .readlock = rcu_torture_read_lock,
472    .read_delay = rcu_read_delay,
473    .readunlock = rcu_torture_read_unlock,
474    .completed = rcu_torture_completed,
475    .deferred_free = rcu_sync_torture_deferred_free,
476    .sync = synchronize_rcu,
477    .call = NULL,
478    .cb_barrier = NULL,
479    .fqs = rcu_force_quiescent_state,
480    .stats = NULL,
481    .irq_capable = 1,
482    .can_boost = rcu_can_boost(),
483    .name = "rcu_sync"
484};
485
486static struct rcu_torture_ops rcu_expedited_ops = {
487    .init = rcu_sync_torture_init,
488    .cleanup = NULL,
489    .readlock = rcu_torture_read_lock,
490    .read_delay = rcu_read_delay, /* just reuse rcu's version. */
491    .readunlock = rcu_torture_read_unlock,
492    .completed = rcu_no_completed,
493    .deferred_free = rcu_sync_torture_deferred_free,
494    .sync = synchronize_rcu_expedited,
495    .call = NULL,
496    .cb_barrier = NULL,
497    .fqs = rcu_force_quiescent_state,
498    .stats = NULL,
499    .irq_capable = 1,
500    .can_boost = rcu_can_boost(),
501    .name = "rcu_expedited"
502};
503
504/*
505 * Definitions for rcu_bh torture testing.
506 */
507
508static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
509{
510    rcu_read_lock_bh();
511    return 0;
512}
513
514static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
515{
516    rcu_read_unlock_bh();
517}
518
519static int rcu_bh_torture_completed(void)
520{
521    return rcu_batches_completed_bh();
522}
523
524static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
525{
526    call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
527}
528
529static struct rcu_torture_ops rcu_bh_ops = {
530    .init = NULL,
531    .cleanup = NULL,
532    .readlock = rcu_bh_torture_read_lock,
533    .read_delay = rcu_read_delay, /* just reuse rcu's version. */
534    .readunlock = rcu_bh_torture_read_unlock,
535    .completed = rcu_bh_torture_completed,
536    .deferred_free = rcu_bh_torture_deferred_free,
537    .sync = synchronize_rcu_bh,
538    .call = call_rcu_bh,
539    .cb_barrier = rcu_barrier_bh,
540    .fqs = rcu_bh_force_quiescent_state,
541    .stats = NULL,
542    .irq_capable = 1,
543    .name = "rcu_bh"
544};
545
546static struct rcu_torture_ops rcu_bh_sync_ops = {
547    .init = rcu_sync_torture_init,
548    .cleanup = NULL,
549    .readlock = rcu_bh_torture_read_lock,
550    .read_delay = rcu_read_delay, /* just reuse rcu's version. */
551    .readunlock = rcu_bh_torture_read_unlock,
552    .completed = rcu_bh_torture_completed,
553    .deferred_free = rcu_sync_torture_deferred_free,
554    .sync = synchronize_rcu_bh,
555    .call = NULL,
556    .cb_barrier = NULL,
557    .fqs = rcu_bh_force_quiescent_state,
558    .stats = NULL,
559    .irq_capable = 1,
560    .name = "rcu_bh_sync"
561};
562
563static struct rcu_torture_ops rcu_bh_expedited_ops = {
564    .init = rcu_sync_torture_init,
565    .cleanup = NULL,
566    .readlock = rcu_bh_torture_read_lock,
567    .read_delay = rcu_read_delay, /* just reuse rcu's version. */
568    .readunlock = rcu_bh_torture_read_unlock,
569    .completed = rcu_bh_torture_completed,
570    .deferred_free = rcu_sync_torture_deferred_free,
571    .sync = synchronize_rcu_bh_expedited,
572    .call = NULL,
573    .cb_barrier = NULL,
574    .fqs = rcu_bh_force_quiescent_state,
575    .stats = NULL,
576    .irq_capable = 1,
577    .name = "rcu_bh_expedited"
578};
579
580/*
581 * Definitions for srcu torture testing.
582 */
583
584static struct srcu_struct srcu_ctl;
585
586static void srcu_torture_init(void)
587{
588    init_srcu_struct(&srcu_ctl);
589    rcu_sync_torture_init();
590}
591
592static void srcu_torture_cleanup(void)
593{
594    synchronize_srcu(&srcu_ctl);
595    cleanup_srcu_struct(&srcu_ctl);
596}
597
598static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
599{
600    return srcu_read_lock(&srcu_ctl);
601}
602
603static void srcu_read_delay(struct rcu_random_state *rrsp)
604{
605    long delay;
606    const long uspertick = 1000000 / HZ;
607    const long longdelay = 10;
608
609    /* We want there to be long-running readers, but not all the time. */
610
611    delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
612    if (!delay)
613        schedule_timeout_interruptible(longdelay);
614    else
615        rcu_read_delay(rrsp);
616}
617
618static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
619{
620    srcu_read_unlock(&srcu_ctl, idx);
621}
622
623static int srcu_torture_completed(void)
624{
625    return srcu_batches_completed(&srcu_ctl);
626}
627
628static void srcu_torture_deferred_free(struct rcu_torture *rp)
629{
630    call_srcu(&srcu_ctl, &rp->rtort_rcu, rcu_torture_cb);
631}
632
633static void srcu_torture_synchronize(void)
634{
635    synchronize_srcu(&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 = srcu_torture_init,
657    .cleanup = srcu_torture_cleanup,
658    .readlock = srcu_torture_read_lock,
659    .read_delay = srcu_read_delay,
660    .readunlock = srcu_torture_read_unlock,
661    .completed = srcu_torture_completed,
662    .deferred_free = srcu_torture_deferred_free,
663    .sync = srcu_torture_synchronize,
664    .call = NULL,
665    .cb_barrier = NULL,
666    .stats = srcu_torture_stats,
667    .name = "srcu"
668};
669
670static struct rcu_torture_ops srcu_sync_ops = {
671    .init = srcu_torture_init,
672    .cleanup = srcu_torture_cleanup,
673    .readlock = srcu_torture_read_lock,
674    .read_delay = srcu_read_delay,
675    .readunlock = srcu_torture_read_unlock,
676    .completed = srcu_torture_completed,
677    .deferred_free = rcu_sync_torture_deferred_free,
678    .sync = srcu_torture_synchronize,
679    .call = NULL,
680    .cb_barrier = NULL,
681    .stats = srcu_torture_stats,
682    .name = "srcu_sync"
683};
684
685static int srcu_torture_read_lock_raw(void) __acquires(&srcu_ctl)
686{
687    return srcu_read_lock_raw(&srcu_ctl);
688}
689
690static void srcu_torture_read_unlock_raw(int idx) __releases(&srcu_ctl)
691{
692    srcu_read_unlock_raw(&srcu_ctl, idx);
693}
694
695static struct rcu_torture_ops srcu_raw_ops = {
696    .init = srcu_torture_init,
697    .cleanup = srcu_torture_cleanup,
698    .readlock = srcu_torture_read_lock_raw,
699    .read_delay = srcu_read_delay,
700    .readunlock = srcu_torture_read_unlock_raw,
701    .completed = srcu_torture_completed,
702    .deferred_free = srcu_torture_deferred_free,
703    .sync = srcu_torture_synchronize,
704    .call = NULL,
705    .cb_barrier = NULL,
706    .stats = srcu_torture_stats,
707    .name = "srcu_raw"
708};
709
710static struct rcu_torture_ops srcu_raw_sync_ops = {
711    .init = srcu_torture_init,
712    .cleanup = srcu_torture_cleanup,
713    .readlock = srcu_torture_read_lock_raw,
714    .read_delay = srcu_read_delay,
715    .readunlock = srcu_torture_read_unlock_raw,
716    .completed = srcu_torture_completed,
717    .deferred_free = rcu_sync_torture_deferred_free,
718    .sync = srcu_torture_synchronize,
719    .call = NULL,
720    .cb_barrier = NULL,
721    .stats = srcu_torture_stats,
722    .name = "srcu_raw_sync"
723};
724
725static void srcu_torture_synchronize_expedited(void)
726{
727    synchronize_srcu_expedited(&srcu_ctl);
728}
729
730static struct rcu_torture_ops srcu_expedited_ops = {
731    .init = srcu_torture_init,
732    .cleanup = srcu_torture_cleanup,
733    .readlock = srcu_torture_read_lock,
734    .read_delay = srcu_read_delay,
735    .readunlock = srcu_torture_read_unlock,
736    .completed = srcu_torture_completed,
737    .deferred_free = rcu_sync_torture_deferred_free,
738    .sync = srcu_torture_synchronize_expedited,
739    .call = NULL,
740    .cb_barrier = NULL,
741    .stats = srcu_torture_stats,
742    .name = "srcu_expedited"
743};
744
745/*
746 * Definitions for sched torture testing.
747 */
748
749static int sched_torture_read_lock(void)
750{
751    preempt_disable();
752    return 0;
753}
754
755static void sched_torture_read_unlock(int idx)
756{
757    preempt_enable();
758}
759
760static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
761{
762    call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
763}
764
765static struct rcu_torture_ops sched_ops = {
766    .init = rcu_sync_torture_init,
767    .cleanup = NULL,
768    .readlock = sched_torture_read_lock,
769    .read_delay = rcu_read_delay, /* just reuse rcu's version. */
770    .readunlock = sched_torture_read_unlock,
771    .completed = rcu_no_completed,
772    .deferred_free = rcu_sched_torture_deferred_free,
773    .sync = synchronize_sched,
774    .cb_barrier = rcu_barrier_sched,
775    .fqs = rcu_sched_force_quiescent_state,
776    .stats = NULL,
777    .irq_capable = 1,
778    .name = "sched"
779};
780
781static struct rcu_torture_ops sched_sync_ops = {
782    .init = rcu_sync_torture_init,
783    .cleanup = NULL,
784    .readlock = sched_torture_read_lock,
785    .read_delay = rcu_read_delay, /* just reuse rcu's version. */
786    .readunlock = sched_torture_read_unlock,
787    .completed = rcu_no_completed,
788    .deferred_free = rcu_sync_torture_deferred_free,
789    .sync = synchronize_sched,
790    .cb_barrier = NULL,
791    .fqs = rcu_sched_force_quiescent_state,
792    .stats = NULL,
793    .name = "sched_sync"
794};
795
796static struct rcu_torture_ops sched_expedited_ops = {
797    .init = rcu_sync_torture_init,
798    .cleanup = NULL,
799    .readlock = sched_torture_read_lock,
800    .read_delay = rcu_read_delay, /* just reuse rcu's version. */
801    .readunlock = sched_torture_read_unlock,
802    .completed = rcu_no_completed,
803    .deferred_free = rcu_sync_torture_deferred_free,
804    .sync = synchronize_sched_expedited,
805    .cb_barrier = NULL,
806    .fqs = rcu_sched_force_quiescent_state,
807    .stats = NULL,
808    .irq_capable = 1,
809    .name = "sched_expedited"
810};
811
812/*
813 * RCU torture priority-boost testing. Runs one real-time thread per
814 * CPU for moderate bursts, repeatedly registering RCU callbacks and
815 * spinning waiting for them to be invoked. If a given callback takes
816 * too long to be invoked, we assume that priority inversion has occurred.
817 */
818
819struct rcu_boost_inflight {
820    struct rcu_head rcu;
821    int inflight;
822};
823
824static void rcu_torture_boost_cb(struct rcu_head *head)
825{
826    struct rcu_boost_inflight *rbip =
827        container_of(head, struct rcu_boost_inflight, rcu);
828
829    smp_mb(); /* Ensure RCU-core accesses precede clearing ->inflight */
830    rbip->inflight = 0;
831}
832
833static int rcu_torture_boost(void *arg)
834{
835    unsigned long call_rcu_time;
836    unsigned long endtime;
837    unsigned long oldstarttime;
838    struct rcu_boost_inflight rbi = { .inflight = 0 };
839    struct sched_param sp;
840
841    VERBOSE_PRINTK_STRING("rcu_torture_boost started");
842
843    /* Set real-time priority. */
844    sp.sched_priority = 1;
845    if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
846        VERBOSE_PRINTK_STRING("rcu_torture_boost RT prio failed!");
847        n_rcu_torture_boost_rterror++;
848    }
849
850    init_rcu_head_on_stack(&rbi.rcu);
851    /* Each pass through the following loop does one boost-test cycle. */
852    do {
853        /* Wait for the next test interval. */
854        oldstarttime = boost_starttime;
855        while (ULONG_CMP_LT(jiffies, oldstarttime)) {
856            schedule_timeout_uninterruptible(1);
857            rcu_stutter_wait("rcu_torture_boost");
858            if (kthread_should_stop() ||
859                fullstop != FULLSTOP_DONTSTOP)
860                goto checkwait;
861        }
862
863        /* Do one boost-test interval. */
864        endtime = oldstarttime + test_boost_duration * HZ;
865        call_rcu_time = jiffies;
866        while (ULONG_CMP_LT(jiffies, endtime)) {
867            /* If we don't have a callback in flight, post one. */
868            if (!rbi.inflight) {
869                smp_mb(); /* RCU core before ->inflight = 1. */
870                rbi.inflight = 1;
871                call_rcu(&rbi.rcu, rcu_torture_boost_cb);
872                if (jiffies - call_rcu_time >
873                     test_boost_duration * HZ - HZ / 2) {
874                    VERBOSE_PRINTK_STRING("rcu_torture_boost boosting failed");
875                    n_rcu_torture_boost_failure++;
876                }
877                call_rcu_time = jiffies;
878            }
879            cond_resched();
880            rcu_stutter_wait("rcu_torture_boost");
881            if (kthread_should_stop() ||
882                fullstop != FULLSTOP_DONTSTOP)
883                goto checkwait;
884        }
885
886        /*
887         * Set the start time of the next test interval.
888         * Yes, this is vulnerable to long delays, but such
889         * delays simply cause a false negative for the next
890         * interval. Besides, we are running at RT priority,
891         * so delays should be relatively rare.
892         */
893        while (oldstarttime == boost_starttime &&
894               !kthread_should_stop()) {
895            if (mutex_trylock(&boost_mutex)) {
896                boost_starttime = jiffies +
897                          test_boost_interval * HZ;
898                n_rcu_torture_boosts++;
899                mutex_unlock(&boost_mutex);
900                break;
901            }
902            schedule_timeout_uninterruptible(1);
903        }
904
905        /* Go do the stutter. */
906checkwait: rcu_stutter_wait("rcu_torture_boost");
907    } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
908
909    /* Clean up and exit. */
910    VERBOSE_PRINTK_STRING("rcu_torture_boost task stopping");
911    rcutorture_shutdown_absorb("rcu_torture_boost");
912    while (!kthread_should_stop() || rbi.inflight)
913        schedule_timeout_uninterruptible(1);
914    smp_mb(); /* order accesses to ->inflight before stack-frame death. */
915    destroy_rcu_head_on_stack(&rbi.rcu);
916    return 0;
917}
918
919/*
920 * RCU torture force-quiescent-state kthread. Repeatedly induces
921 * bursts of calls to force_quiescent_state(), increasing the probability
922 * of occurrence of some important types of race conditions.
923 */
924static int
925rcu_torture_fqs(void *arg)
926{
927    unsigned long fqs_resume_time;
928    int fqs_burst_remaining;
929
930    VERBOSE_PRINTK_STRING("rcu_torture_fqs task started");
931    do {
932        fqs_resume_time = jiffies + fqs_stutter * HZ;
933        while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
934               !kthread_should_stop()) {
935            schedule_timeout_interruptible(1);
936        }
937        fqs_burst_remaining = fqs_duration;
938        while (fqs_burst_remaining > 0 &&
939               !kthread_should_stop()) {
940            cur_ops->fqs();
941            udelay(fqs_holdoff);
942            fqs_burst_remaining -= fqs_holdoff;
943        }
944        rcu_stutter_wait("rcu_torture_fqs");
945    } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
946    VERBOSE_PRINTK_STRING("rcu_torture_fqs task stopping");
947    rcutorture_shutdown_absorb("rcu_torture_fqs");
948    while (!kthread_should_stop())
949        schedule_timeout_uninterruptible(1);
950    return 0;
951}
952
953/*
954 * RCU torture writer kthread. Repeatedly substitutes a new structure
955 * for that pointed to by rcu_torture_current, freeing the old structure
956 * after a series of grace periods (the "pipeline").
957 */
958static int
959rcu_torture_writer(void *arg)
960{
961    int i;
962    long oldbatch = rcu_batches_completed();
963    struct rcu_torture *rp;
964    struct rcu_torture *old_rp;
965    static DEFINE_RCU_RANDOM(rand);
966
967    VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
968    set_user_nice(current, 19);
969
970    do {
971        schedule_timeout_uninterruptible(1);
972        rp = rcu_torture_alloc();
973        if (rp == NULL)
974            continue;
975        rp->rtort_pipe_count = 0;
976        udelay(rcu_random(&rand) & 0x3ff);
977        old_rp = rcu_dereference_check(rcu_torture_current,
978                           current == writer_task);
979        rp->rtort_mbtest = 1;
980        rcu_assign_pointer(rcu_torture_current, rp);
981        smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
982        if (old_rp) {
983            i = old_rp->rtort_pipe_count;
984            if (i > RCU_TORTURE_PIPE_LEN)
985                i = RCU_TORTURE_PIPE_LEN;
986            atomic_inc(&rcu_torture_wcount[i]);
987            old_rp->rtort_pipe_count++;
988            cur_ops->deferred_free(old_rp);
989        }
990        rcutorture_record_progress(++rcu_torture_current_version);
991        oldbatch = cur_ops->completed();
992        rcu_stutter_wait("rcu_torture_writer");
993    } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
994    VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
995    rcutorture_shutdown_absorb("rcu_torture_writer");
996    while (!kthread_should_stop())
997        schedule_timeout_uninterruptible(1);
998    return 0;
999}
1000
1001/*
1002 * RCU torture fake writer kthread. Repeatedly calls sync, with a random
1003 * delay between calls.
1004 */
1005static int
1006rcu_torture_fakewriter(void *arg)
1007{
1008    DEFINE_RCU_RANDOM(rand);
1009
1010    VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
1011    set_user_nice(current, 19);
1012
1013    do {
1014        schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
1015        udelay(rcu_random(&rand) & 0x3ff);
1016        cur_ops->sync();
1017        rcu_stutter_wait("rcu_torture_fakewriter");
1018    } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1019
1020    VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
1021    rcutorture_shutdown_absorb("rcu_torture_fakewriter");
1022    while (!kthread_should_stop())
1023        schedule_timeout_uninterruptible(1);
1024    return 0;
1025}
1026
1027void rcutorture_trace_dump(void)
1028{
1029    static atomic_t beenhere = ATOMIC_INIT(0);
1030
1031    if (atomic_read(&beenhere))
1032        return;
1033    if (atomic_xchg(&beenhere, 1) != 0)
1034        return;
1035    do_trace_rcu_torture_read(cur_ops->name, (struct rcu_head *)~0UL);
1036    ftrace_dump(DUMP_ALL);
1037}
1038
1039/*
1040 * RCU torture reader from timer handler. Dereferences rcu_torture_current,
1041 * incrementing the corresponding element of the pipeline array. The
1042 * counter in the element should never be greater than 1, otherwise, the
1043 * RCU implementation is broken.
1044 */
1045static void rcu_torture_timer(unsigned long unused)
1046{
1047    int idx;
1048    int completed;
1049    static DEFINE_RCU_RANDOM(rand);
1050    static DEFINE_SPINLOCK(rand_lock);
1051    struct rcu_torture *p;
1052    int pipe_count;
1053
1054    idx = cur_ops->readlock();
1055    completed = cur_ops->completed();
1056    p = rcu_dereference_check(rcu_torture_current,
1057                  rcu_read_lock_bh_held() ||
1058                  rcu_read_lock_sched_held() ||
1059                  srcu_read_lock_held(&srcu_ctl));
1060    if (p == NULL) {
1061        /* Leave because rcu_torture_writer is not yet underway */
1062        cur_ops->readunlock(idx);
1063        return;
1064    }
1065    do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu);
1066    if (p->rtort_mbtest == 0)
1067        atomic_inc(&n_rcu_torture_mberror);
1068    spin_lock(&rand_lock);
1069    cur_ops->read_delay(&rand);
1070    n_rcu_torture_timers++;
1071    spin_unlock(&rand_lock);
1072    preempt_disable();
1073    pipe_count = p->rtort_pipe_count;
1074    if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1075        /* Should not happen, but... */
1076        pipe_count = RCU_TORTURE_PIPE_LEN;
1077    }
1078    if (pipe_count > 1)
1079        rcutorture_trace_dump();
1080    __this_cpu_inc(rcu_torture_count[pipe_count]);
1081    completed = cur_ops->completed() - completed;
1082    if (completed > RCU_TORTURE_PIPE_LEN) {
1083        /* Should not happen, but... */
1084        completed = RCU_TORTURE_PIPE_LEN;
1085    }
1086    __this_cpu_inc(rcu_torture_batch[completed]);
1087    preempt_enable();
1088    cur_ops->readunlock(idx);
1089}
1090
1091/*
1092 * RCU torture reader kthread. Repeatedly dereferences rcu_torture_current,
1093 * incrementing the corresponding element of the pipeline array. The
1094 * counter in the element should never be greater than 1, otherwise, the
1095 * RCU implementation is broken.
1096 */
1097static int
1098rcu_torture_reader(void *arg)
1099{
1100    int completed;
1101    int idx;
1102    DEFINE_RCU_RANDOM(rand);
1103    struct rcu_torture *p;
1104    int pipe_count;
1105    struct timer_list t;
1106
1107    VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
1108    set_user_nice(current, 19);
1109    if (irqreader && cur_ops->irq_capable)
1110        setup_timer_on_stack(&t, rcu_torture_timer, 0);
1111
1112    do {
1113        if (irqreader && cur_ops->irq_capable) {
1114            if (!timer_pending(&t))
1115                mod_timer(&t, jiffies + 1);
1116        }
1117        idx = cur_ops->readlock();
1118        completed = cur_ops->completed();
1119        p = rcu_dereference_check(rcu_torture_current,
1120                      rcu_read_lock_bh_held() ||
1121                      rcu_read_lock_sched_held() ||
1122                      srcu_read_lock_held(&srcu_ctl));
1123        if (p == NULL) {
1124            /* Wait for rcu_torture_writer to get underway */
1125            cur_ops->readunlock(idx);
1126            schedule_timeout_interruptible(HZ);
1127            continue;
1128        }
1129        do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu);
1130        if (p->rtort_mbtest == 0)
1131            atomic_inc(&n_rcu_torture_mberror);
1132        cur_ops->read_delay(&rand);
1133        preempt_disable();
1134        pipe_count = p->rtort_pipe_count;
1135        if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1136            /* Should not happen, but... */
1137            pipe_count = RCU_TORTURE_PIPE_LEN;
1138        }
1139        if (pipe_count > 1)
1140            rcutorture_trace_dump();
1141        __this_cpu_inc(rcu_torture_count[pipe_count]);
1142        completed = cur_ops->completed() - completed;
1143        if (completed > RCU_TORTURE_PIPE_LEN) {
1144            /* Should not happen, but... */
1145            completed = RCU_TORTURE_PIPE_LEN;
1146        }
1147        __this_cpu_inc(rcu_torture_batch[completed]);
1148        preempt_enable();
1149        cur_ops->readunlock(idx);
1150        schedule();
1151        rcu_stutter_wait("rcu_torture_reader");
1152    } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1153    VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
1154    rcutorture_shutdown_absorb("rcu_torture_reader");
1155    if (irqreader && cur_ops->irq_capable)
1156        del_timer_sync(&t);
1157    while (!kthread_should_stop())
1158        schedule_timeout_uninterruptible(1);
1159    return 0;
1160}
1161
1162/*
1163 * Create an RCU-torture statistics message in the specified buffer.
1164 */
1165static int
1166rcu_torture_printk(char *page)
1167{
1168    int cnt = 0;
1169    int cpu;
1170    int i;
1171    long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1172    long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1173
1174    for_each_possible_cpu(cpu) {
1175        for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1176            pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1177            batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1178        }
1179    }
1180    for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1181        if (pipesummary[i] != 0)
1182            break;
1183    }
1184    cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
1185    cnt += sprintf(&page[cnt],
1186               "rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d "
1187               "rtmbe: %d rtbke: %ld rtbre: %ld "
1188               "rtbf: %ld rtb: %ld nt: %ld "
1189               "onoff: %ld/%ld:%ld/%ld "
1190               "barrier: %ld/%ld:%ld",
1191               rcu_torture_current,
1192               rcu_torture_current_version,
1193               list_empty(&rcu_torture_freelist),
1194               atomic_read(&n_rcu_torture_alloc),
1195               atomic_read(&n_rcu_torture_alloc_fail),
1196               atomic_read(&n_rcu_torture_free),
1197               atomic_read(&n_rcu_torture_mberror),
1198               n_rcu_torture_boost_ktrerror,
1199               n_rcu_torture_boost_rterror,
1200               n_rcu_torture_boost_failure,
1201               n_rcu_torture_boosts,
1202               n_rcu_torture_timers,
1203               n_online_successes,
1204               n_online_attempts,
1205               n_offline_successes,
1206               n_offline_attempts,
1207               n_barrier_successes,
1208               n_barrier_attempts,
1209               n_rcu_torture_barrier_error);
1210    cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1211    if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1212        n_rcu_torture_barrier_error != 0 ||
1213        n_rcu_torture_boost_ktrerror != 0 ||
1214        n_rcu_torture_boost_rterror != 0 ||
1215        n_rcu_torture_boost_failure != 0 ||
1216        i > 1) {
1217        cnt += sprintf(&page[cnt], "!!! ");
1218        atomic_inc(&n_rcu_torture_error);
1219        WARN_ON_ONCE(1);
1220    }
1221    cnt += sprintf(&page[cnt], "Reader Pipe: ");
1222    for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1223        cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
1224    cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1225    cnt += sprintf(&page[cnt], "Reader Batch: ");
1226    for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1227        cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
1228    cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1229    cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
1230    for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1231        cnt += sprintf(&page[cnt], " %d",
1232                   atomic_read(&rcu_torture_wcount[i]));
1233    }
1234    cnt += sprintf(&page[cnt], "\n");
1235    if (cur_ops->stats)
1236        cnt += cur_ops->stats(&page[cnt]);
1237    return cnt;
1238}
1239
1240/*
1241 * Print torture statistics. Caller must ensure that there is only
1242 * one call to this function at a given time!!! This is normally
1243 * accomplished by relying on the module system to only have one copy
1244 * of the module loaded, and then by giving the rcu_torture_stats
1245 * kthread full control (or the init/cleanup functions when rcu_torture_stats
1246 * thread is not running).
1247 */
1248static void
1249rcu_torture_stats_print(void)
1250{
1251    int cnt;
1252
1253    cnt = rcu_torture_printk(printk_buf);
1254    printk(KERN_ALERT "%s", printk_buf);
1255}
1256
1257/*
1258 * Periodically prints torture statistics, if periodic statistics printing
1259 * was specified via the stat_interval module parameter.
1260 *
1261 * No need to worry about fullstop here, since this one doesn't reference
1262 * volatile state or register callbacks.
1263 */
1264static int
1265rcu_torture_stats(void *arg)
1266{
1267    VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
1268    do {
1269        schedule_timeout_interruptible(stat_interval * HZ);
1270        rcu_torture_stats_print();
1271        rcutorture_shutdown_absorb("rcu_torture_stats");
1272    } while (!kthread_should_stop());
1273    VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
1274    return 0;
1275}
1276
1277static int rcu_idle_cpu; /* Force all torture tasks off this CPU */
1278
1279/* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
1280 * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
1281 */
1282static void rcu_torture_shuffle_tasks(void)
1283{
1284    int i;
1285
1286    cpumask_setall(shuffle_tmp_mask);
1287    get_online_cpus();
1288
1289    /* No point in shuffling if there is only one online CPU (ex: UP) */
1290    if (num_online_cpus() == 1) {
1291        put_online_cpus();
1292        return;
1293    }
1294
1295    if (rcu_idle_cpu != -1)
1296        cpumask_clear_cpu(rcu_idle_cpu, shuffle_tmp_mask);
1297
1298    set_cpus_allowed_ptr(current, shuffle_tmp_mask);
1299
1300    if (reader_tasks) {
1301        for (i = 0; i < nrealreaders; i++)
1302            if (reader_tasks[i])
1303                set_cpus_allowed_ptr(reader_tasks[i],
1304                             shuffle_tmp_mask);
1305    }
1306
1307    if (fakewriter_tasks) {
1308        for (i = 0; i < nfakewriters; i++)
1309            if (fakewriter_tasks[i])
1310                set_cpus_allowed_ptr(fakewriter_tasks[i],
1311                             shuffle_tmp_mask);
1312    }
1313
1314    if (writer_task)
1315        set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
1316
1317    if (stats_task)
1318        set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
1319
1320    if (rcu_idle_cpu == -1)
1321        rcu_idle_cpu = num_online_cpus() - 1;
1322    else
1323        rcu_idle_cpu--;
1324
1325    put_online_cpus();
1326}
1327
1328/* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
1329 * system to become idle at a time and cut off its timer ticks. This is meant
1330 * to test the support for such tickless idle CPU in RCU.
1331 */
1332static int
1333rcu_torture_shuffle(void *arg)
1334{
1335    VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
1336    do {
1337        schedule_timeout_interruptible(shuffle_interval * HZ);
1338        rcu_torture_shuffle_tasks();
1339        rcutorture_shutdown_absorb("rcu_torture_shuffle");
1340    } while (!kthread_should_stop());
1341    VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
1342    return 0;
1343}
1344
1345/* Cause the rcutorture test to "stutter", starting and stopping all
1346 * threads periodically.
1347 */
1348static int
1349rcu_torture_stutter(void *arg)
1350{
1351    VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
1352    do {
1353        schedule_timeout_interruptible(stutter * HZ);
1354        stutter_pause_test = 1;
1355        if (!kthread_should_stop())
1356            schedule_timeout_interruptible(stutter * HZ);
1357        stutter_pause_test = 0;
1358        rcutorture_shutdown_absorb("rcu_torture_stutter");
1359    } while (!kthread_should_stop());
1360    VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
1361    return 0;
1362}
1363
1364static inline void
1365rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, char *tag)
1366{
1367    printk(KERN_ALERT "%s" TORTURE_FLAG
1368        "--- %s: nreaders=%d nfakewriters=%d "
1369        "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1370        "shuffle_interval=%d stutter=%d irqreader=%d "
1371        "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1372        "test_boost=%d/%d test_boost_interval=%d "
1373        "test_boost_duration=%d shutdown_secs=%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        onoff_interval, onoff_holdoff);
1381}
1382
1383static struct notifier_block rcutorture_shutdown_nb = {
1384    .notifier_call = rcutorture_shutdown_notify,
1385};
1386
1387static void rcutorture_booster_cleanup(int cpu)
1388{
1389    struct task_struct *t;
1390
1391    if (boost_tasks[cpu] == NULL)
1392        return;
1393    mutex_lock(&boost_mutex);
1394    VERBOSE_PRINTK_STRING("Stopping rcu_torture_boost task");
1395    t = boost_tasks[cpu];
1396    boost_tasks[cpu] = NULL;
1397    mutex_unlock(&boost_mutex);
1398
1399    /* This must be outside of the mutex, otherwise deadlock! */
1400    kthread_stop(t);
1401    boost_tasks[cpu] = NULL;
1402}
1403
1404static int rcutorture_booster_init(int cpu)
1405{
1406    int retval;
1407
1408    if (boost_tasks[cpu] != NULL)
1409        return 0; /* Already created, nothing more to do. */
1410
1411    /* Don't allow time recalculation while creating a new task. */
1412    mutex_lock(&boost_mutex);
1413    VERBOSE_PRINTK_STRING("Creating rcu_torture_boost task");
1414    boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1415                          cpu_to_node(cpu),
1416                          "rcu_torture_boost");
1417    if (IS_ERR(boost_tasks[cpu])) {
1418        retval = PTR_ERR(boost_tasks[cpu]);
1419        VERBOSE_PRINTK_STRING("rcu_torture_boost task create failed");
1420        n_rcu_torture_boost_ktrerror++;
1421        boost_tasks[cpu] = NULL;
1422        mutex_unlock(&boost_mutex);
1423        return retval;
1424    }
1425    kthread_bind(boost_tasks[cpu], cpu);
1426    wake_up_process(boost_tasks[cpu]);
1427    mutex_unlock(&boost_mutex);
1428    return 0;
1429}
1430
1431/*
1432 * Cause the rcutorture test to shutdown the system after the test has
1433 * run for the time specified by the shutdown_secs module parameter.
1434 */
1435static int
1436rcu_torture_shutdown(void *arg)
1437{
1438    long delta;
1439    unsigned long jiffies_snap;
1440
1441    VERBOSE_PRINTK_STRING("rcu_torture_shutdown task started");
1442    jiffies_snap = ACCESS_ONCE(jiffies);
1443    while (ULONG_CMP_LT(jiffies_snap, shutdown_time) &&
1444           !kthread_should_stop()) {
1445        delta = shutdown_time - jiffies_snap;
1446        if (verbose)
1447            printk(KERN_ALERT "%s" TORTURE_FLAG
1448                   "rcu_torture_shutdown task: %lu "
1449                   "jiffies remaining\n",
1450                   torture_type, delta);
1451        schedule_timeout_interruptible(delta);
1452        jiffies_snap = ACCESS_ONCE(jiffies);
1453    }
1454    if (kthread_should_stop()) {
1455        VERBOSE_PRINTK_STRING("rcu_torture_shutdown task stopping");
1456        return 0;
1457    }
1458
1459    /* OK, shut down the system. */
1460
1461    VERBOSE_PRINTK_STRING("rcu_torture_shutdown task shutting down system");
1462    shutdown_task = NULL; /* Avoid self-kill deadlock. */
1463    rcu_torture_cleanup(); /* Get the success/failure message. */
1464    kernel_power_off(); /* Shut down the system. */
1465    return 0;
1466}
1467
1468#ifdef CONFIG_HOTPLUG_CPU
1469
1470/*
1471 * Execute random CPU-hotplug operations at the interval specified
1472 * by the onoff_interval.
1473 */
1474static int __cpuinit
1475rcu_torture_onoff(void *arg)
1476{
1477    int cpu;
1478    int maxcpu = -1;
1479    DEFINE_RCU_RANDOM(rand);
1480
1481    VERBOSE_PRINTK_STRING("rcu_torture_onoff task started");
1482    for_each_online_cpu(cpu)
1483        maxcpu = cpu;
1484    WARN_ON(maxcpu < 0);
1485    if (onoff_holdoff > 0) {
1486        VERBOSE_PRINTK_STRING("rcu_torture_onoff begin holdoff");
1487        schedule_timeout_interruptible(onoff_holdoff * HZ);
1488        VERBOSE_PRINTK_STRING("rcu_torture_onoff end holdoff");
1489    }
1490    while (!kthread_should_stop()) {
1491        cpu = (rcu_random(&rand) >> 4) % (maxcpu + 1);
1492        if (cpu_online(cpu) && cpu_is_hotpluggable(cpu)) {
1493            if (verbose)
1494                printk(KERN_ALERT "%s" TORTURE_FLAG
1495                       "rcu_torture_onoff task: offlining %d\n",
1496                       torture_type, cpu);
1497            n_offline_attempts++;
1498            if (cpu_down(cpu) == 0) {
1499                if (verbose)
1500                    printk(KERN_ALERT "%s" TORTURE_FLAG
1501                           "rcu_torture_onoff task: "
1502                           "offlined %d\n",
1503                           torture_type, cpu);
1504                n_offline_successes++;
1505            }
1506        } else if (cpu_is_hotpluggable(cpu)) {
1507            if (verbose)
1508                printk(KERN_ALERT "%s" TORTURE_FLAG
1509                       "rcu_torture_onoff task: onlining %d\n",
1510                       torture_type, cpu);
1511            n_online_attempts++;
1512            if (cpu_up(cpu) == 0) {
1513                if (verbose)
1514                    printk(KERN_ALERT "%s" TORTURE_FLAG
1515                           "rcu_torture_onoff task: "
1516                           "onlined %d\n",
1517                           torture_type, cpu);
1518                n_online_successes++;
1519            }
1520        }
1521        schedule_timeout_interruptible(onoff_interval * HZ);
1522    }
1523    VERBOSE_PRINTK_STRING("rcu_torture_onoff task stopping");
1524    return 0;
1525}
1526
1527static int __cpuinit
1528rcu_torture_onoff_init(void)
1529{
1530    int ret;
1531
1532    if (onoff_interval <= 0)
1533        return 0;
1534    onoff_task = kthread_run(rcu_torture_onoff, NULL, "rcu_torture_onoff");
1535    if (IS_ERR(onoff_task)) {
1536        ret = PTR_ERR(onoff_task);
1537        onoff_task = NULL;
1538        return ret;
1539    }
1540    return 0;
1541}
1542
1543static void rcu_torture_onoff_cleanup(void)
1544{
1545    if (onoff_task == NULL)
1546        return;
1547    VERBOSE_PRINTK_STRING("Stopping rcu_torture_onoff task");
1548    kthread_stop(onoff_task);
1549    onoff_task = NULL;
1550}
1551
1552#else /* #ifdef CONFIG_HOTPLUG_CPU */
1553
1554static int
1555rcu_torture_onoff_init(void)
1556{
1557    return 0;
1558}
1559
1560static void rcu_torture_onoff_cleanup(void)
1561{
1562}
1563
1564#endif /* #else #ifdef CONFIG_HOTPLUG_CPU */
1565
1566/*
1567 * CPU-stall kthread. It waits as specified by stall_cpu_holdoff, then
1568 * induces a CPU stall for the time specified by stall_cpu.
1569 */
1570static int __cpuinit rcu_torture_stall(void *args)
1571{
1572    unsigned long stop_at;
1573
1574    VERBOSE_PRINTK_STRING("rcu_torture_stall task started");
1575    if (stall_cpu_holdoff > 0) {
1576        VERBOSE_PRINTK_STRING("rcu_torture_stall begin holdoff");
1577        schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1578        VERBOSE_PRINTK_STRING("rcu_torture_stall end holdoff");
1579    }
1580    if (!kthread_should_stop()) {
1581        stop_at = get_seconds() + stall_cpu;
1582        /* RCU CPU stall is expected behavior in following code. */
1583        printk(KERN_ALERT "rcu_torture_stall start.\n");
1584        rcu_read_lock();
1585        preempt_disable();
1586        while (ULONG_CMP_LT(get_seconds(), stop_at))
1587            continue; /* Induce RCU CPU stall warning. */
1588        preempt_enable();
1589        rcu_read_unlock();
1590        printk(KERN_ALERT "rcu_torture_stall end.\n");
1591    }
1592    rcutorture_shutdown_absorb("rcu_torture_stall");
1593    while (!kthread_should_stop())
1594        schedule_timeout_interruptible(10 * HZ);
1595    return 0;
1596}
1597
1598/* Spawn CPU-stall kthread, if stall_cpu specified. */
1599static int __init rcu_torture_stall_init(void)
1600{
1601    int ret;
1602
1603    if (stall_cpu <= 0)
1604        return 0;
1605    stall_task = kthread_run(rcu_torture_stall, NULL, "rcu_torture_stall");
1606    if (IS_ERR(stall_task)) {
1607        ret = PTR_ERR(stall_task);
1608        stall_task = NULL;
1609        return ret;
1610    }
1611    return 0;
1612}
1613
1614/* Clean up after the CPU-stall kthread, if one was spawned. */
1615static void rcu_torture_stall_cleanup(void)
1616{
1617    if (stall_task == NULL)
1618        return;
1619    VERBOSE_PRINTK_STRING("Stopping rcu_torture_stall_task.");
1620    kthread_stop(stall_task);
1621    stall_task = NULL;
1622}
1623
1624/* Callback function for RCU barrier testing. */
1625void rcu_torture_barrier_cbf(struct rcu_head *rcu)
1626{
1627    atomic_inc(&barrier_cbs_invoked);
1628}
1629
1630/* kthread function to register callbacks used to test RCU barriers. */
1631static int rcu_torture_barrier_cbs(void *arg)
1632{
1633    long myid = (long)arg;
1634    struct rcu_head rcu;
1635
1636    init_rcu_head_on_stack(&rcu);
1637    VERBOSE_PRINTK_STRING("rcu_torture_barrier_cbs task started");
1638    set_user_nice(current, 19);
1639    do {
1640        wait_event(barrier_cbs_wq[myid],
1641               atomic_read(&barrier_cbs_count) == n_barrier_cbs ||
1642               kthread_should_stop() ||
1643               fullstop != FULLSTOP_DONTSTOP);
1644        if (kthread_should_stop() || fullstop != FULLSTOP_DONTSTOP)
1645            break;
1646        cur_ops->call(&rcu, rcu_torture_barrier_cbf);
1647        if (atomic_dec_and_test(&barrier_cbs_count))
1648            wake_up(&barrier_wq);
1649    } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1650    VERBOSE_PRINTK_STRING("rcu_torture_barrier_cbs task stopping");
1651    rcutorture_shutdown_absorb("rcu_torture_barrier_cbs");
1652    while (!kthread_should_stop())
1653        schedule_timeout_interruptible(1);
1654    cur_ops->cb_barrier();
1655    destroy_rcu_head_on_stack(&rcu);
1656    return 0;
1657}
1658
1659/* kthread function to drive and coordinate RCU barrier testing. */
1660static int rcu_torture_barrier(void *arg)
1661{
1662    int i;
1663
1664    VERBOSE_PRINTK_STRING("rcu_torture_barrier task starting");
1665    do {
1666        atomic_set(&barrier_cbs_invoked, 0);
1667        atomic_set(&barrier_cbs_count, n_barrier_cbs);
1668        /* wake_up() path contains the required barriers. */
1669        for (i = 0; i < n_barrier_cbs; i++)
1670            wake_up(&barrier_cbs_wq[i]);
1671        wait_event(barrier_wq,
1672               atomic_read(&barrier_cbs_count) == 0 ||
1673               kthread_should_stop() ||
1674               fullstop != FULLSTOP_DONTSTOP);
1675        if (kthread_should_stop() || fullstop != FULLSTOP_DONTSTOP)
1676            break;
1677        n_barrier_attempts++;
1678        cur_ops->cb_barrier();
1679        if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
1680            n_rcu_torture_barrier_error++;
1681            WARN_ON_ONCE(1);
1682        }
1683        n_barrier_successes++;
1684        schedule_timeout_interruptible(HZ / 10);
1685    } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1686    VERBOSE_PRINTK_STRING("rcu_torture_barrier task stopping");
1687    rcutorture_shutdown_absorb("rcu_torture_barrier_cbs");
1688    while (!kthread_should_stop())
1689        schedule_timeout_interruptible(1);
1690    return 0;
1691}
1692
1693/* Initialize RCU barrier testing. */
1694static int rcu_torture_barrier_init(void)
1695{
1696    int i;
1697    int ret;
1698
1699    if (n_barrier_cbs == 0)
1700        return 0;
1701    if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
1702        printk(KERN_ALERT "%s" TORTURE_FLAG
1703               " Call or barrier ops missing for %s,\n",
1704               torture_type, cur_ops->name);
1705        printk(KERN_ALERT "%s" TORTURE_FLAG
1706               " RCU barrier testing omitted from run.\n",
1707               torture_type);
1708        return 0;
1709    }
1710    atomic_set(&barrier_cbs_count, 0);
1711    atomic_set(&barrier_cbs_invoked, 0);
1712    barrier_cbs_tasks =
1713        kzalloc(n_barrier_cbs * sizeof(barrier_cbs_tasks[0]),
1714            GFP_KERNEL);
1715    barrier_cbs_wq =
1716        kzalloc(n_barrier_cbs * sizeof(barrier_cbs_wq[0]),
1717            GFP_KERNEL);
1718    if (barrier_cbs_tasks == NULL || barrier_cbs_wq == 0)
1719        return -ENOMEM;
1720    for (i = 0; i < n_barrier_cbs; i++) {
1721        init_waitqueue_head(&barrier_cbs_wq[i]);
1722        barrier_cbs_tasks[i] = kthread_run(rcu_torture_barrier_cbs,
1723                           (void *)(long)i,
1724                           "rcu_torture_barrier_cbs");
1725        if (IS_ERR(barrier_cbs_tasks[i])) {
1726            ret = PTR_ERR(barrier_cbs_tasks[i]);
1727            VERBOSE_PRINTK_ERRSTRING("Failed to create rcu_torture_barrier_cbs");
1728            barrier_cbs_tasks[i] = NULL;
1729            return ret;
1730        }
1731    }
1732    barrier_task = kthread_run(rcu_torture_barrier, NULL,
1733                   "rcu_torture_barrier");
1734    if (IS_ERR(barrier_task)) {
1735        ret = PTR_ERR(barrier_task);
1736        VERBOSE_PRINTK_ERRSTRING("Failed to create rcu_torture_barrier");
1737        barrier_task = NULL;
1738    }
1739    return 0;
1740}
1741
1742/* Clean up after RCU barrier testing. */
1743static void rcu_torture_barrier_cleanup(void)
1744{
1745    int i;
1746
1747    if (barrier_task != NULL) {
1748        VERBOSE_PRINTK_STRING("Stopping rcu_torture_barrier task");
1749        kthread_stop(barrier_task);
1750        barrier_task = NULL;
1751    }
1752    if (barrier_cbs_tasks != NULL) {
1753        for (i = 0; i < n_barrier_cbs; i++) {
1754            if (barrier_cbs_tasks[i] != NULL) {
1755                VERBOSE_PRINTK_STRING("Stopping rcu_torture_barrier_cbs task");
1756                kthread_stop(barrier_cbs_tasks[i]);
1757                barrier_cbs_tasks[i] = NULL;
1758            }
1759        }
1760        kfree(barrier_cbs_tasks);
1761        barrier_cbs_tasks = NULL;
1762    }
1763    if (barrier_cbs_wq != NULL) {
1764        kfree(barrier_cbs_wq);
1765        barrier_cbs_wq = NULL;
1766    }
1767}
1768
1769static int rcutorture_cpu_notify(struct notifier_block *self,
1770                 unsigned long action, void *hcpu)
1771{
1772    long cpu = (long)hcpu;
1773
1774    switch (action) {
1775    case CPU_ONLINE:
1776    case CPU_DOWN_FAILED:
1777        (void)rcutorture_booster_init(cpu);
1778        break;
1779    case CPU_DOWN_PREPARE:
1780        rcutorture_booster_cleanup(cpu);
1781        break;
1782    default:
1783        break;
1784    }
1785    return NOTIFY_OK;
1786}
1787
1788static struct notifier_block rcutorture_cpu_nb = {
1789    .notifier_call = rcutorture_cpu_notify,
1790};
1791
1792static void
1793rcu_torture_cleanup(void)
1794{
1795    int i;
1796
1797    mutex_lock(&fullstop_mutex);
1798    rcutorture_record_test_transition();
1799    if (fullstop == FULLSTOP_SHUTDOWN) {
1800        printk(KERN_WARNING /* but going down anyway, so... */
1801               "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
1802        mutex_unlock(&fullstop_mutex);
1803        schedule_timeout_uninterruptible(10);
1804        if (cur_ops->cb_barrier != NULL)
1805            cur_ops->cb_barrier();
1806        return;
1807    }
1808    fullstop = FULLSTOP_RMMOD;
1809    mutex_unlock(&fullstop_mutex);
1810    unregister_reboot_notifier(&rcutorture_shutdown_nb);
1811    rcu_torture_barrier_cleanup();
1812    rcu_torture_stall_cleanup();
1813    if (stutter_task) {
1814        VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
1815        kthread_stop(stutter_task);
1816    }
1817    stutter_task = NULL;
1818    if (shuffler_task) {
1819        VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
1820        kthread_stop(shuffler_task);
1821        free_cpumask_var(shuffle_tmp_mask);
1822    }
1823    shuffler_task = NULL;
1824
1825    if (writer_task) {
1826        VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
1827        kthread_stop(writer_task);
1828    }
1829    writer_task = NULL;
1830
1831    if (reader_tasks) {
1832        for (i = 0; i < nrealreaders; i++) {
1833            if (reader_tasks[i]) {
1834                VERBOSE_PRINTK_STRING(
1835                    "Stopping rcu_torture_reader task");
1836                kthread_stop(reader_tasks[i]);
1837            }
1838            reader_tasks[i] = NULL;
1839        }
1840        kfree(reader_tasks);
1841        reader_tasks = NULL;
1842    }
1843    rcu_torture_current = NULL;
1844
1845    if (fakewriter_tasks) {
1846        for (i = 0; i < nfakewriters; i++) {
1847            if (fakewriter_tasks[i]) {
1848                VERBOSE_PRINTK_STRING(
1849                    "Stopping rcu_torture_fakewriter task");
1850                kthread_stop(fakewriter_tasks[i]);
1851            }
1852            fakewriter_tasks[i] = NULL;
1853        }
1854        kfree(fakewriter_tasks);
1855        fakewriter_tasks = NULL;
1856    }
1857
1858    if (stats_task) {
1859        VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
1860        kthread_stop(stats_task);
1861    }
1862    stats_task = NULL;
1863
1864    if (fqs_task) {
1865        VERBOSE_PRINTK_STRING("Stopping rcu_torture_fqs task");
1866        kthread_stop(fqs_task);
1867    }
1868    fqs_task = NULL;
1869    if ((test_boost == 1 && cur_ops->can_boost) ||
1870        test_boost == 2) {
1871        unregister_cpu_notifier(&rcutorture_cpu_nb);
1872        for_each_possible_cpu(i)
1873            rcutorture_booster_cleanup(i);
1874    }
1875    if (shutdown_task != NULL) {
1876        VERBOSE_PRINTK_STRING("Stopping rcu_torture_shutdown task");
1877        kthread_stop(shutdown_task);
1878    }
1879    shutdown_task = NULL;
1880    rcu_torture_onoff_cleanup();
1881
1882    /* Wait for all RCU callbacks to fire. */
1883
1884    if (cur_ops->cb_barrier != NULL)
1885        cur_ops->cb_barrier();
1886
1887    rcu_torture_stats_print(); /* -After- the stats thread is stopped! */
1888
1889    if (cur_ops->cleanup)
1890        cur_ops->cleanup();
1891    if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
1892        rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1893    else if (n_online_successes != n_online_attempts ||
1894         n_offline_successes != n_offline_attempts)
1895        rcu_torture_print_module_parms(cur_ops,
1896                           "End of test: RCU_HOTPLUG");
1897    else
1898        rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1899}
1900
1901static int __init
1902rcu_torture_init(void)
1903{
1904    int i;
1905    int cpu;
1906    int firsterr = 0;
1907    int retval;
1908    static struct rcu_torture_ops *torture_ops[] =
1909        { &rcu_ops, &rcu_sync_ops, &rcu_expedited_ops,
1910          &rcu_bh_ops, &rcu_bh_sync_ops, &rcu_bh_expedited_ops,
1911          &srcu_ops, &srcu_sync_ops, &srcu_raw_ops,
1912          &srcu_raw_sync_ops, &srcu_expedited_ops,
1913          &sched_ops, &sched_sync_ops, &sched_expedited_ops, };
1914
1915    mutex_lock(&fullstop_mutex);
1916
1917    /* Process args and tell the world that the torturer is on the job. */
1918    for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1919        cur_ops = torture_ops[i];
1920        if (strcmp(torture_type, cur_ops->name) == 0)
1921            break;
1922    }
1923    if (i == ARRAY_SIZE(torture_ops)) {
1924        printk(KERN_ALERT "rcu-torture: invalid torture type: \"%s\"\n",
1925               torture_type);
1926        printk(KERN_ALERT "rcu-torture types:");
1927        for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1928            printk(KERN_ALERT " %s", torture_ops[i]->name);
1929        printk(KERN_ALERT "\n");
1930        mutex_unlock(&fullstop_mutex);
1931        return -EINVAL;
1932    }
1933    if (cur_ops->fqs == NULL && fqs_duration != 0) {
1934        printk(KERN_ALERT "rcu-torture: ->fqs NULL and non-zero "
1935                  "fqs_duration, fqs disabled.\n");
1936        fqs_duration = 0;
1937    }
1938    if (cur_ops->init)
1939        cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1940
1941    if (nreaders >= 0)
1942        nrealreaders = nreaders;
1943    else
1944        nrealreaders = 2 * num_online_cpus();
1945    rcu_torture_print_module_parms(cur_ops, "Start of test");
1946    fullstop = FULLSTOP_DONTSTOP;
1947
1948    /* Set up the freelist. */
1949
1950    INIT_LIST_HEAD(&rcu_torture_freelist);
1951    for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1952        rcu_tortures[i].rtort_mbtest = 0;
1953        list_add_tail(&rcu_tortures[i].rtort_free,
1954                  &rcu_torture_freelist);
1955    }
1956
1957    /* Initialize the statistics so that each run gets its own numbers. */
1958
1959    rcu_torture_current = NULL;
1960    rcu_torture_current_version = 0;
1961    atomic_set(&n_rcu_torture_alloc, 0);
1962    atomic_set(&n_rcu_torture_alloc_fail, 0);
1963    atomic_set(&n_rcu_torture_free, 0);
1964    atomic_set(&n_rcu_torture_mberror, 0);
1965    atomic_set(&n_rcu_torture_error, 0);
1966    n_rcu_torture_barrier_error = 0;
1967    n_rcu_torture_boost_ktrerror = 0;
1968    n_rcu_torture_boost_rterror = 0;
1969    n_rcu_torture_boost_failure = 0;
1970    n_rcu_torture_boosts = 0;
1971    for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1972        atomic_set(&rcu_torture_wcount[i], 0);
1973    for_each_possible_cpu(cpu) {
1974        for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1975            per_cpu(rcu_torture_count, cpu)[i] = 0;
1976            per_cpu(rcu_torture_batch, cpu)[i] = 0;
1977        }
1978    }
1979
1980    /* Start up the kthreads. */
1981
1982    VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
1983    writer_task = kthread_run(rcu_torture_writer, NULL,
1984                  "rcu_torture_writer");
1985    if (IS_ERR(writer_task)) {
1986        firsterr = PTR_ERR(writer_task);
1987        VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
1988        writer_task = NULL;
1989        goto unwind;
1990    }
1991    fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1992                   GFP_KERNEL);
1993    if (fakewriter_tasks == NULL) {
1994        VERBOSE_PRINTK_ERRSTRING("out of memory");
1995        firsterr = -ENOMEM;
1996        goto unwind;
1997    }
1998    for (i = 0; i < nfakewriters; i++) {
1999        VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
2000        fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
2001                          "rcu_torture_fakewriter");
2002        if (IS_ERR(fakewriter_tasks[i])) {
2003            firsterr = PTR_ERR(fakewriter_tasks[i]);
2004            VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
2005            fakewriter_tasks[i] = NULL;
2006            goto unwind;
2007        }
2008    }
2009    reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
2010                   GFP_KERNEL);
2011    if (reader_tasks == NULL) {
2012        VERBOSE_PRINTK_ERRSTRING("out of memory");
2013        firsterr = -ENOMEM;
2014        goto unwind;
2015    }
2016    for (i = 0; i < nrealreaders; i++) {
2017        VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
2018        reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
2019                          "rcu_torture_reader");
2020        if (IS_ERR(reader_tasks[i])) {
2021            firsterr = PTR_ERR(reader_tasks[i]);
2022            VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
2023            reader_tasks[i] = NULL;
2024            goto unwind;
2025        }
2026    }
2027    if (stat_interval > 0) {
2028        VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
2029        stats_task = kthread_run(rcu_torture_stats, NULL,
2030                    "rcu_torture_stats");
2031        if (IS_ERR(stats_task)) {
2032            firsterr = PTR_ERR(stats_task);
2033            VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
2034            stats_task = NULL;
2035            goto unwind;
2036        }
2037    }
2038    if (test_no_idle_hz) {
2039        rcu_idle_cpu = num_online_cpus() - 1;
2040
2041        if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
2042            firsterr = -ENOMEM;
2043            VERBOSE_PRINTK_ERRSTRING("Failed to alloc mask");
2044            goto unwind;
2045        }
2046
2047        /* Create the shuffler thread */
2048        shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
2049                      "rcu_torture_shuffle");
2050        if (IS_ERR(shuffler_task)) {
2051            free_cpumask_var(shuffle_tmp_mask);
2052            firsterr = PTR_ERR(shuffler_task);
2053            VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
2054            shuffler_task = NULL;
2055            goto unwind;
2056        }
2057    }
2058    if (stutter < 0)
2059        stutter = 0;
2060    if (stutter) {
2061        /* Create the stutter thread */
2062        stutter_task = kthread_run(rcu_torture_stutter, NULL,
2063                      "rcu_torture_stutter");
2064        if (IS_ERR(stutter_task)) {
2065            firsterr = PTR_ERR(stutter_task);
2066            VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
2067            stutter_task = NULL;
2068            goto unwind;
2069        }
2070    }
2071    if (fqs_duration < 0)
2072        fqs_duration = 0;
2073    if (fqs_duration) {
2074        /* Create the stutter thread */
2075        fqs_task = kthread_run(rcu_torture_fqs, NULL,
2076                       "rcu_torture_fqs");
2077        if (IS_ERR(fqs_task)) {
2078            firsterr = PTR_ERR(fqs_task);
2079            VERBOSE_PRINTK_ERRSTRING("Failed to create fqs");
2080            fqs_task = NULL;
2081            goto unwind;
2082        }
2083    }
2084    if (test_boost_interval < 1)
2085        test_boost_interval = 1;
2086    if (test_boost_duration < 2)
2087        test_boost_duration = 2;
2088    if ((test_boost == 1 && cur_ops->can_boost) ||
2089        test_boost == 2) {
2090
2091        boost_starttime = jiffies + test_boost_interval * HZ;
2092        register_cpu_notifier(&rcutorture_cpu_nb);
2093        for_each_possible_cpu(i) {
2094            if (cpu_is_offline(i))
2095                continue; /* Heuristic: CPU can go offline. */
2096            retval = rcutorture_booster_init(i);
2097            if (retval < 0) {
2098                firsterr = retval;
2099                goto unwind;
2100            }
2101        }
2102    }
2103    if (shutdown_secs > 0) {
2104        shutdown_time = jiffies + shutdown_secs * HZ;
2105        shutdown_task = kthread_run(rcu_torture_shutdown, NULL,
2106                        "rcu_torture_shutdown");
2107        if (IS_ERR(shutdown_task)) {
2108            firsterr = PTR_ERR(shutdown_task);
2109            VERBOSE_PRINTK_ERRSTRING("Failed to create shutdown");
2110            shutdown_task = NULL;
2111            goto unwind;
2112        }
2113    }
2114    i = rcu_torture_onoff_init();
2115    if (i != 0) {
2116        firsterr = i;
2117        goto unwind;
2118    }
2119    register_reboot_notifier(&rcutorture_shutdown_nb);
2120    i = rcu_torture_stall_init();
2121    if (i != 0) {
2122        firsterr = i;
2123        goto unwind;
2124    }
2125    retval = rcu_torture_barrier_init();
2126    if (retval != 0) {
2127        firsterr = retval;
2128        goto unwind;
2129    }
2130    rcutorture_record_test_transition();
2131    mutex_unlock(&fullstop_mutex);
2132    return 0;
2133
2134unwind:
2135    mutex_unlock(&fullstop_mutex);
2136    rcu_torture_cleanup();
2137    return firsterr;
2138}
2139
2140module_init(rcu_torture_init);
2141module_exit(rcu_torture_cleanup);
2142

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