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TOMOYO Linux Cross Reference
Linux/kernel/rcu/rcutorture.c

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  1 /*
  2  * Read-Copy Update module-based torture test facility
  3  *
  4  * This program is free software; you can redistribute it and/or modify
  5  * it under the terms of the GNU General Public License as published by
  6  * the Free Software Foundation; either version 2 of the License, or
  7  * (at your option) any later version.
  8  *
  9  * This program is distributed in the hope that it will be useful,
 10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 12  * GNU General Public License for more details.
 13  *
 14  * You should have received a copy of the GNU General Public License
 15  * along with this program; if not, you can access it online at
 16  * http://www.gnu.org/licenses/gpl-2.0.html.
 17  *
 18  * Copyright (C) IBM Corporation, 2005, 2006
 19  *
 20  * Authors: Paul E. McKenney <paulmck@us.ibm.com>
 21  *        Josh Triplett <josh@joshtriplett.org>
 22  *
 23  * See also:  Documentation/RCU/torture.txt
 24  */
 25 
 26 #define pr_fmt(fmt) fmt
 27 
 28 #include <linux/types.h>
 29 #include <linux/kernel.h>
 30 #include <linux/init.h>
 31 #include <linux/module.h>
 32 #include <linux/kthread.h>
 33 #include <linux/err.h>
 34 #include <linux/spinlock.h>
 35 #include <linux/smp.h>
 36 #include <linux/rcupdate.h>
 37 #include <linux/interrupt.h>
 38 #include <linux/sched/signal.h>
 39 #include <uapi/linux/sched/types.h>
 40 #include <linux/atomic.h>
 41 #include <linux/bitops.h>
 42 #include <linux/completion.h>
 43 #include <linux/moduleparam.h>
 44 #include <linux/percpu.h>
 45 #include <linux/notifier.h>
 46 #include <linux/reboot.h>
 47 #include <linux/freezer.h>
 48 #include <linux/cpu.h>
 49 #include <linux/delay.h>
 50 #include <linux/stat.h>
 51 #include <linux/srcu.h>
 52 #include <linux/slab.h>
 53 #include <linux/trace_clock.h>
 54 #include <asm/byteorder.h>
 55 #include <linux/torture.h>
 56 #include <linux/vmalloc.h>
 57 #include <linux/sched/debug.h>
 58 #include <linux/sched/sysctl.h>
 59 
 60 #include "rcu.h"
 61 
 62 MODULE_LICENSE("GPL");
 63 MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and Josh Triplett <josh@joshtriplett.org>");
 64 
 65 
 66 /* Bits for ->extendables field, extendables param, and related definitions. */
 67 #define RCUTORTURE_RDR_SHIFT     8      /* Put SRCU index in upper bits. */
 68 #define RCUTORTURE_RDR_MASK      ((1 << RCUTORTURE_RDR_SHIFT) - 1)
 69 #define RCUTORTURE_RDR_BH        0x1    /* Extend readers by disabling bh. */
 70 #define RCUTORTURE_RDR_IRQ       0x2    /*  ... disabling interrupts. */
 71 #define RCUTORTURE_RDR_PREEMPT   0x4    /*  ... disabling preemption. */
 72 #define RCUTORTURE_RDR_RCU       0x8    /*  ... entering another RCU reader. */
 73 #define RCUTORTURE_RDR_NBITS     4      /* Number of bits defined above. */
 74 #define RCUTORTURE_MAX_EXTEND    (RCUTORTURE_RDR_BH | RCUTORTURE_RDR_IRQ | \
 75                                   RCUTORTURE_RDR_PREEMPT)
 76 #define RCUTORTURE_RDR_MAX_LOOPS 0x7    /* Maximum reader extensions. */
 77                                         /* Must be power of two minus one. */
 78 
 79 torture_param(int, cbflood_inter_holdoff, HZ,
 80               "Holdoff between floods (jiffies)");
 81 torture_param(int, cbflood_intra_holdoff, 1,
 82               "Holdoff between bursts (jiffies)");
 83 torture_param(int, cbflood_n_burst, 3, "# bursts in flood, zero to disable");
 84 torture_param(int, cbflood_n_per_burst, 20000,
 85               "# callbacks per burst in flood");
 86 torture_param(int, extendables, RCUTORTURE_MAX_EXTEND,
 87               "Extend readers by disabling bh (1), irqs (2), or preempt (4)");
 88 torture_param(int, fqs_duration, 0,
 89               "Duration of fqs bursts (us), 0 to disable");
 90 torture_param(int, fqs_holdoff, 0, "Holdoff time within fqs bursts (us)");
 91 torture_param(int, fqs_stutter, 3, "Wait time between fqs bursts (s)");
 92 torture_param(bool, gp_cond, false, "Use conditional/async GP wait primitives");
 93 torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
 94 torture_param(bool, gp_normal, false,
 95              "Use normal (non-expedited) GP wait primitives");
 96 torture_param(bool, gp_sync, false, "Use synchronous GP wait primitives");
 97 torture_param(int, irqreader, 1, "Allow RCU readers from irq handlers");
 98 torture_param(int, n_barrier_cbs, 0,
 99              "# of callbacks/kthreads for barrier testing");
100 torture_param(int, nfakewriters, 4, "Number of RCU fake writer threads");
101 torture_param(int, nreaders, -1, "Number of RCU reader threads");
102 torture_param(int, object_debug, 0,
103              "Enable debug-object double call_rcu() testing");
104 torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)");
105 torture_param(int, onoff_interval, 0,
106              "Time between CPU hotplugs (jiffies), 0=disable");
107 torture_param(int, shuffle_interval, 3, "Number of seconds between shuffles");
108 torture_param(int, shutdown_secs, 0, "Shutdown time (s), <= zero to disable.");
109 torture_param(int, stall_cpu, 0, "Stall duration (s), zero to disable.");
110 torture_param(int, stall_cpu_holdoff, 10,
111              "Time to wait before starting stall (s).");
112 torture_param(int, stall_cpu_irqsoff, 0, "Disable interrupts while stalling.");
113 torture_param(int, stat_interval, 60,
114              "Number of seconds between stats printk()s");
115 torture_param(int, stutter, 5, "Number of seconds to run/halt test");
116 torture_param(int, test_boost, 1, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
117 torture_param(int, test_boost_duration, 4,
118              "Duration of each boost test, seconds.");
119 torture_param(int, test_boost_interval, 7,
120              "Interval between boost tests, seconds.");
121 torture_param(bool, test_no_idle_hz, true,
122              "Test support for tickless idle CPUs");
123 torture_param(int, verbose, 1,
124              "Enable verbose debugging printk()s");
125 
126 static char *torture_type = "rcu";
127 module_param(torture_type, charp, 0444);
128 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, ...)");
129 
130 static int nrealreaders;
131 static int ncbflooders;
132 static struct task_struct *writer_task;
133 static struct task_struct **fakewriter_tasks;
134 static struct task_struct **reader_tasks;
135 static struct task_struct *stats_task;
136 static struct task_struct **cbflood_task;
137 static struct task_struct *fqs_task;
138 static struct task_struct *boost_tasks[NR_CPUS];
139 static struct task_struct *stall_task;
140 static struct task_struct **barrier_cbs_tasks;
141 static struct task_struct *barrier_task;
142 
143 #define RCU_TORTURE_PIPE_LEN 10
144 
145 struct rcu_torture {
146         struct rcu_head rtort_rcu;
147         int rtort_pipe_count;
148         struct list_head rtort_free;
149         int rtort_mbtest;
150 };
151 
152 static LIST_HEAD(rcu_torture_freelist);
153 static struct rcu_torture __rcu *rcu_torture_current;
154 static unsigned long rcu_torture_current_version;
155 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
156 static DEFINE_SPINLOCK(rcu_torture_lock);
157 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count);
158 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch);
159 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
160 static atomic_t n_rcu_torture_alloc;
161 static atomic_t n_rcu_torture_alloc_fail;
162 static atomic_t n_rcu_torture_free;
163 static atomic_t n_rcu_torture_mberror;
164 static atomic_t n_rcu_torture_error;
165 static long n_rcu_torture_barrier_error;
166 static long n_rcu_torture_boost_ktrerror;
167 static long n_rcu_torture_boost_rterror;
168 static long n_rcu_torture_boost_failure;
169 static long n_rcu_torture_boosts;
170 static atomic_long_t n_rcu_torture_timers;
171 static long n_barrier_attempts;
172 static long n_barrier_successes; /* did rcu_barrier test succeed? */
173 static atomic_long_t n_cbfloods;
174 static struct list_head rcu_torture_removed;
175 
176 static int rcu_torture_writer_state;
177 #define RTWS_FIXED_DELAY        0
178 #define RTWS_DELAY              1
179 #define RTWS_REPLACE            2
180 #define RTWS_DEF_FREE           3
181 #define RTWS_EXP_SYNC           4
182 #define RTWS_COND_GET           5
183 #define RTWS_COND_SYNC          6
184 #define RTWS_SYNC               7
185 #define RTWS_STUTTER            8
186 #define RTWS_STOPPING           9
187 static const char * const rcu_torture_writer_state_names[] = {
188         "RTWS_FIXED_DELAY",
189         "RTWS_DELAY",
190         "RTWS_REPLACE",
191         "RTWS_DEF_FREE",
192         "RTWS_EXP_SYNC",
193         "RTWS_COND_GET",
194         "RTWS_COND_SYNC",
195         "RTWS_SYNC",
196         "RTWS_STUTTER",
197         "RTWS_STOPPING",
198 };
199 
200 static const char *rcu_torture_writer_state_getname(void)
201 {
202         unsigned int i = READ_ONCE(rcu_torture_writer_state);
203 
204         if (i >= ARRAY_SIZE(rcu_torture_writer_state_names))
205                 return "???";
206         return rcu_torture_writer_state_names[i];
207 }
208 
209 #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
210 #define rcu_can_boost() 1
211 #else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
212 #define rcu_can_boost() 0
213 #endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
214 
215 #ifdef CONFIG_RCU_TRACE
216 static u64 notrace rcu_trace_clock_local(void)
217 {
218         u64 ts = trace_clock_local();
219 
220         (void)do_div(ts, NSEC_PER_USEC);
221         return ts;
222 }
223 #else /* #ifdef CONFIG_RCU_TRACE */
224 static u64 notrace rcu_trace_clock_local(void)
225 {
226         return 0ULL;
227 }
228 #endif /* #else #ifdef CONFIG_RCU_TRACE */
229 
230 static unsigned long boost_starttime;   /* jiffies of next boost test start. */
231 static DEFINE_MUTEX(boost_mutex);       /* protect setting boost_starttime */
232                                         /*  and boost task create/destroy. */
233 static atomic_t barrier_cbs_count;      /* Barrier callbacks registered. */
234 static bool barrier_phase;              /* Test phase. */
235 static atomic_t barrier_cbs_invoked;    /* Barrier callbacks invoked. */
236 static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */
237 static DECLARE_WAIT_QUEUE_HEAD(barrier_wq);
238 
239 /*
240  * Allocate an element from the rcu_tortures pool.
241  */
242 static struct rcu_torture *
243 rcu_torture_alloc(void)
244 {
245         struct list_head *p;
246 
247         spin_lock_bh(&rcu_torture_lock);
248         if (list_empty(&rcu_torture_freelist)) {
249                 atomic_inc(&n_rcu_torture_alloc_fail);
250                 spin_unlock_bh(&rcu_torture_lock);
251                 return NULL;
252         }
253         atomic_inc(&n_rcu_torture_alloc);
254         p = rcu_torture_freelist.next;
255         list_del_init(p);
256         spin_unlock_bh(&rcu_torture_lock);
257         return container_of(p, struct rcu_torture, rtort_free);
258 }
259 
260 /*
261  * Free an element to the rcu_tortures pool.
262  */
263 static void
264 rcu_torture_free(struct rcu_torture *p)
265 {
266         atomic_inc(&n_rcu_torture_free);
267         spin_lock_bh(&rcu_torture_lock);
268         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
269         spin_unlock_bh(&rcu_torture_lock);
270 }
271 
272 /*
273  * Operations vector for selecting different types of tests.
274  */
275 
276 struct rcu_torture_ops {
277         int ttype;
278         void (*init)(void);
279         void (*cleanup)(void);
280         int (*readlock)(void);
281         void (*read_delay)(struct torture_random_state *rrsp);
282         void (*readunlock)(int idx);
283         unsigned long (*get_gp_seq)(void);
284         unsigned long (*gp_diff)(unsigned long new, unsigned long old);
285         void (*deferred_free)(struct rcu_torture *p);
286         void (*sync)(void);
287         void (*exp_sync)(void);
288         unsigned long (*get_state)(void);
289         void (*cond_sync)(unsigned long oldstate);
290         call_rcu_func_t call;
291         void (*cb_barrier)(void);
292         void (*fqs)(void);
293         void (*stats)(void);
294         int irq_capable;
295         int can_boost;
296         int extendables;
297         int ext_irq_conflict;
298         const char *name;
299 };
300 
301 static struct rcu_torture_ops *cur_ops;
302 
303 /*
304  * Definitions for rcu torture testing.
305  */
306 
307 static int rcu_torture_read_lock(void) __acquires(RCU)
308 {
309         rcu_read_lock();
310         return 0;
311 }
312 
313 static void rcu_read_delay(struct torture_random_state *rrsp)
314 {
315         unsigned long started;
316         unsigned long completed;
317         const unsigned long shortdelay_us = 200;
318         const unsigned long longdelay_ms = 50;
319         unsigned long long ts;
320 
321         /* We want a short delay sometimes to make a reader delay the grace
322          * period, and we want a long delay occasionally to trigger
323          * force_quiescent_state. */
324 
325         if (!(torture_random(rrsp) % (nrealreaders * 2000 * longdelay_ms))) {
326                 started = cur_ops->get_gp_seq();
327                 ts = rcu_trace_clock_local();
328                 mdelay(longdelay_ms);
329                 completed = cur_ops->get_gp_seq();
330                 do_trace_rcu_torture_read(cur_ops->name, NULL, ts,
331                                           started, completed);
332         }
333         if (!(torture_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
334                 udelay(shortdelay_us);
335         if (!preempt_count() &&
336             !(torture_random(rrsp) % (nrealreaders * 500)))
337                 torture_preempt_schedule();  /* QS only if preemptible. */
338 }
339 
340 static void rcu_torture_read_unlock(int idx) __releases(RCU)
341 {
342         rcu_read_unlock();
343 }
344 
345 /*
346  * Update callback in the pipe.  This should be invoked after a grace period.
347  */
348 static bool
349 rcu_torture_pipe_update_one(struct rcu_torture *rp)
350 {
351         int i;
352 
353         i = rp->rtort_pipe_count;
354         if (i > RCU_TORTURE_PIPE_LEN)
355                 i = RCU_TORTURE_PIPE_LEN;
356         atomic_inc(&rcu_torture_wcount[i]);
357         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
358                 rp->rtort_mbtest = 0;
359                 return true;
360         }
361         return false;
362 }
363 
364 /*
365  * Update all callbacks in the pipe.  Suitable for synchronous grace-period
366  * primitives.
367  */
368 static void
369 rcu_torture_pipe_update(struct rcu_torture *old_rp)
370 {
371         struct rcu_torture *rp;
372         struct rcu_torture *rp1;
373 
374         if (old_rp)
375                 list_add(&old_rp->rtort_free, &rcu_torture_removed);
376         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
377                 if (rcu_torture_pipe_update_one(rp)) {
378                         list_del(&rp->rtort_free);
379                         rcu_torture_free(rp);
380                 }
381         }
382 }
383 
384 static void
385 rcu_torture_cb(struct rcu_head *p)
386 {
387         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
388 
389         if (torture_must_stop_irq()) {
390                 /* Test is ending, just drop callbacks on the floor. */
391                 /* The next initialization will pick up the pieces. */
392                 return;
393         }
394         if (rcu_torture_pipe_update_one(rp))
395                 rcu_torture_free(rp);
396         else
397                 cur_ops->deferred_free(rp);
398 }
399 
400 static unsigned long rcu_no_completed(void)
401 {
402         return 0;
403 }
404 
405 static void rcu_torture_deferred_free(struct rcu_torture *p)
406 {
407         call_rcu(&p->rtort_rcu, rcu_torture_cb);
408 }
409 
410 static void rcu_sync_torture_init(void)
411 {
412         INIT_LIST_HEAD(&rcu_torture_removed);
413 }
414 
415 static struct rcu_torture_ops rcu_ops = {
416         .ttype          = RCU_FLAVOR,
417         .init           = rcu_sync_torture_init,
418         .readlock       = rcu_torture_read_lock,
419         .read_delay     = rcu_read_delay,
420         .readunlock     = rcu_torture_read_unlock,
421         .get_gp_seq     = rcu_get_gp_seq,
422         .gp_diff        = rcu_seq_diff,
423         .deferred_free  = rcu_torture_deferred_free,
424         .sync           = synchronize_rcu,
425         .exp_sync       = synchronize_rcu_expedited,
426         .get_state      = get_state_synchronize_rcu,
427         .cond_sync      = cond_synchronize_rcu,
428         .call           = call_rcu,
429         .cb_barrier     = rcu_barrier,
430         .fqs            = rcu_force_quiescent_state,
431         .stats          = NULL,
432         .irq_capable    = 1,
433         .can_boost      = rcu_can_boost(),
434         .name           = "rcu"
435 };
436 
437 /*
438  * Definitions for rcu_bh torture testing.
439  */
440 
441 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
442 {
443         rcu_read_lock_bh();
444         return 0;
445 }
446 
447 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
448 {
449         rcu_read_unlock_bh();
450 }
451 
452 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
453 {
454         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
455 }
456 
457 static struct rcu_torture_ops rcu_bh_ops = {
458         .ttype          = RCU_BH_FLAVOR,
459         .init           = rcu_sync_torture_init,
460         .readlock       = rcu_bh_torture_read_lock,
461         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
462         .readunlock     = rcu_bh_torture_read_unlock,
463         .get_gp_seq     = rcu_bh_get_gp_seq,
464         .gp_diff        = rcu_seq_diff,
465         .deferred_free  = rcu_bh_torture_deferred_free,
466         .sync           = synchronize_rcu_bh,
467         .exp_sync       = synchronize_rcu_bh_expedited,
468         .call           = call_rcu_bh,
469         .cb_barrier     = rcu_barrier_bh,
470         .fqs            = rcu_bh_force_quiescent_state,
471         .stats          = NULL,
472         .irq_capable    = 1,
473         .extendables    = (RCUTORTURE_RDR_BH | RCUTORTURE_RDR_IRQ),
474         .ext_irq_conflict = RCUTORTURE_RDR_RCU,
475         .name           = "rcu_bh"
476 };
477 
478 /*
479  * Don't even think about trying any of these in real life!!!
480  * The names includes "busted", and they really means it!
481  * The only purpose of these functions is to provide a buggy RCU
482  * implementation to make sure that rcutorture correctly emits
483  * buggy-RCU error messages.
484  */
485 static void rcu_busted_torture_deferred_free(struct rcu_torture *p)
486 {
487         /* This is a deliberate bug for testing purposes only! */
488         rcu_torture_cb(&p->rtort_rcu);
489 }
490 
491 static void synchronize_rcu_busted(void)
492 {
493         /* This is a deliberate bug for testing purposes only! */
494 }
495 
496 static void
497 call_rcu_busted(struct rcu_head *head, rcu_callback_t func)
498 {
499         /* This is a deliberate bug for testing purposes only! */
500         func(head);
501 }
502 
503 static struct rcu_torture_ops rcu_busted_ops = {
504         .ttype          = INVALID_RCU_FLAVOR,
505         .init           = rcu_sync_torture_init,
506         .readlock       = rcu_torture_read_lock,
507         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
508         .readunlock     = rcu_torture_read_unlock,
509         .get_gp_seq     = rcu_no_completed,
510         .deferred_free  = rcu_busted_torture_deferred_free,
511         .sync           = synchronize_rcu_busted,
512         .exp_sync       = synchronize_rcu_busted,
513         .call           = call_rcu_busted,
514         .cb_barrier     = NULL,
515         .fqs            = NULL,
516         .stats          = NULL,
517         .irq_capable    = 1,
518         .name           = "busted"
519 };
520 
521 /*
522  * Definitions for srcu torture testing.
523  */
524 
525 DEFINE_STATIC_SRCU(srcu_ctl);
526 static struct srcu_struct srcu_ctld;
527 static struct srcu_struct *srcu_ctlp = &srcu_ctl;
528 
529 static int srcu_torture_read_lock(void) __acquires(srcu_ctlp)
530 {
531         return srcu_read_lock(srcu_ctlp);
532 }
533 
534 static void srcu_read_delay(struct torture_random_state *rrsp)
535 {
536         long delay;
537         const long uspertick = 1000000 / HZ;
538         const long longdelay = 10;
539 
540         /* We want there to be long-running readers, but not all the time. */
541 
542         delay = torture_random(rrsp) %
543                 (nrealreaders * 2 * longdelay * uspertick);
544         if (!delay && in_task())
545                 schedule_timeout_interruptible(longdelay);
546         else
547                 rcu_read_delay(rrsp);
548 }
549 
550 static void srcu_torture_read_unlock(int idx) __releases(srcu_ctlp)
551 {
552         srcu_read_unlock(srcu_ctlp, idx);
553 }
554 
555 static unsigned long srcu_torture_completed(void)
556 {
557         return srcu_batches_completed(srcu_ctlp);
558 }
559 
560 static void srcu_torture_deferred_free(struct rcu_torture *rp)
561 {
562         call_srcu(srcu_ctlp, &rp->rtort_rcu, rcu_torture_cb);
563 }
564 
565 static void srcu_torture_synchronize(void)
566 {
567         synchronize_srcu(srcu_ctlp);
568 }
569 
570 static void srcu_torture_call(struct rcu_head *head,
571                               rcu_callback_t func)
572 {
573         call_srcu(srcu_ctlp, head, func);
574 }
575 
576 static void srcu_torture_barrier(void)
577 {
578         srcu_barrier(srcu_ctlp);
579 }
580 
581 static void srcu_torture_stats(void)
582 {
583         srcu_torture_stats_print(srcu_ctlp, torture_type, TORTURE_FLAG);
584 }
585 
586 static void srcu_torture_synchronize_expedited(void)
587 {
588         synchronize_srcu_expedited(srcu_ctlp);
589 }
590 
591 static struct rcu_torture_ops srcu_ops = {
592         .ttype          = SRCU_FLAVOR,
593         .init           = rcu_sync_torture_init,
594         .readlock       = srcu_torture_read_lock,
595         .read_delay     = srcu_read_delay,
596         .readunlock     = srcu_torture_read_unlock,
597         .get_gp_seq     = srcu_torture_completed,
598         .deferred_free  = srcu_torture_deferred_free,
599         .sync           = srcu_torture_synchronize,
600         .exp_sync       = srcu_torture_synchronize_expedited,
601         .call           = srcu_torture_call,
602         .cb_barrier     = srcu_torture_barrier,
603         .stats          = srcu_torture_stats,
604         .irq_capable    = 1,
605         .name           = "srcu"
606 };
607 
608 static void srcu_torture_init(void)
609 {
610         rcu_sync_torture_init();
611         WARN_ON(init_srcu_struct(&srcu_ctld));
612         srcu_ctlp = &srcu_ctld;
613 }
614 
615 static void srcu_torture_cleanup(void)
616 {
617         static DEFINE_TORTURE_RANDOM(rand);
618 
619         if (torture_random(&rand) & 0x800)
620                 cleanup_srcu_struct(&srcu_ctld);
621         else
622                 cleanup_srcu_struct_quiesced(&srcu_ctld);
623         srcu_ctlp = &srcu_ctl; /* In case of a later rcutorture run. */
624 }
625 
626 /* As above, but dynamically allocated. */
627 static struct rcu_torture_ops srcud_ops = {
628         .ttype          = SRCU_FLAVOR,
629         .init           = srcu_torture_init,
630         .cleanup        = srcu_torture_cleanup,
631         .readlock       = srcu_torture_read_lock,
632         .read_delay     = srcu_read_delay,
633         .readunlock     = srcu_torture_read_unlock,
634         .get_gp_seq     = srcu_torture_completed,
635         .deferred_free  = srcu_torture_deferred_free,
636         .sync           = srcu_torture_synchronize,
637         .exp_sync       = srcu_torture_synchronize_expedited,
638         .call           = srcu_torture_call,
639         .cb_barrier     = srcu_torture_barrier,
640         .stats          = srcu_torture_stats,
641         .irq_capable    = 1,
642         .name           = "srcud"
643 };
644 
645 /* As above, but broken due to inappropriate reader extension. */
646 static struct rcu_torture_ops busted_srcud_ops = {
647         .ttype          = SRCU_FLAVOR,
648         .init           = srcu_torture_init,
649         .cleanup        = srcu_torture_cleanup,
650         .readlock       = srcu_torture_read_lock,
651         .read_delay     = rcu_read_delay,
652         .readunlock     = srcu_torture_read_unlock,
653         .get_gp_seq     = srcu_torture_completed,
654         .deferred_free  = srcu_torture_deferred_free,
655         .sync           = srcu_torture_synchronize,
656         .exp_sync       = srcu_torture_synchronize_expedited,
657         .call           = srcu_torture_call,
658         .cb_barrier     = srcu_torture_barrier,
659         .stats          = srcu_torture_stats,
660         .irq_capable    = 1,
661         .extendables    = RCUTORTURE_MAX_EXTEND,
662         .name           = "busted_srcud"
663 };
664 
665 /*
666  * Definitions for sched torture testing.
667  */
668 
669 static int sched_torture_read_lock(void)
670 {
671         preempt_disable();
672         return 0;
673 }
674 
675 static void sched_torture_read_unlock(int idx)
676 {
677         preempt_enable();
678 }
679 
680 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
681 {
682         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
683 }
684 
685 static struct rcu_torture_ops sched_ops = {
686         .ttype          = RCU_SCHED_FLAVOR,
687         .init           = rcu_sync_torture_init,
688         .readlock       = sched_torture_read_lock,
689         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
690         .readunlock     = sched_torture_read_unlock,
691         .get_gp_seq     = rcu_sched_get_gp_seq,
692         .gp_diff        = rcu_seq_diff,
693         .deferred_free  = rcu_sched_torture_deferred_free,
694         .sync           = synchronize_sched,
695         .exp_sync       = synchronize_sched_expedited,
696         .get_state      = get_state_synchronize_sched,
697         .cond_sync      = cond_synchronize_sched,
698         .call           = call_rcu_sched,
699         .cb_barrier     = rcu_barrier_sched,
700         .fqs            = rcu_sched_force_quiescent_state,
701         .stats          = NULL,
702         .irq_capable    = 1,
703         .extendables    = RCUTORTURE_MAX_EXTEND,
704         .name           = "sched"
705 };
706 
707 /*
708  * Definitions for RCU-tasks torture testing.
709  */
710 
711 static int tasks_torture_read_lock(void)
712 {
713         return 0;
714 }
715 
716 static void tasks_torture_read_unlock(int idx)
717 {
718 }
719 
720 static void rcu_tasks_torture_deferred_free(struct rcu_torture *p)
721 {
722         call_rcu_tasks(&p->rtort_rcu, rcu_torture_cb);
723 }
724 
725 static struct rcu_torture_ops tasks_ops = {
726         .ttype          = RCU_TASKS_FLAVOR,
727         .init           = rcu_sync_torture_init,
728         .readlock       = tasks_torture_read_lock,
729         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
730         .readunlock     = tasks_torture_read_unlock,
731         .get_gp_seq     = rcu_no_completed,
732         .deferred_free  = rcu_tasks_torture_deferred_free,
733         .sync           = synchronize_rcu_tasks,
734         .exp_sync       = synchronize_rcu_tasks,
735         .call           = call_rcu_tasks,
736         .cb_barrier     = rcu_barrier_tasks,
737         .fqs            = NULL,
738         .stats          = NULL,
739         .irq_capable    = 1,
740         .name           = "tasks"
741 };
742 
743 static unsigned long rcutorture_seq_diff(unsigned long new, unsigned long old)
744 {
745         if (!cur_ops->gp_diff)
746                 return new - old;
747         return cur_ops->gp_diff(new, old);
748 }
749 
750 static bool __maybe_unused torturing_tasks(void)
751 {
752         return cur_ops == &tasks_ops;
753 }
754 
755 /*
756  * RCU torture priority-boost testing.  Runs one real-time thread per
757  * CPU for moderate bursts, repeatedly registering RCU callbacks and
758  * spinning waiting for them to be invoked.  If a given callback takes
759  * too long to be invoked, we assume that priority inversion has occurred.
760  */
761 
762 struct rcu_boost_inflight {
763         struct rcu_head rcu;
764         int inflight;
765 };
766 
767 static void rcu_torture_boost_cb(struct rcu_head *head)
768 {
769         struct rcu_boost_inflight *rbip =
770                 container_of(head, struct rcu_boost_inflight, rcu);
771 
772         /* Ensure RCU-core accesses precede clearing ->inflight */
773         smp_store_release(&rbip->inflight, 0);
774 }
775 
776 static int old_rt_runtime = -1;
777 
778 static void rcu_torture_disable_rt_throttle(void)
779 {
780         /*
781          * Disable RT throttling so that rcutorture's boost threads don't get
782          * throttled. Only possible if rcutorture is built-in otherwise the
783          * user should manually do this by setting the sched_rt_period_us and
784          * sched_rt_runtime sysctls.
785          */
786         if (!IS_BUILTIN(CONFIG_RCU_TORTURE_TEST) || old_rt_runtime != -1)
787                 return;
788 
789         old_rt_runtime = sysctl_sched_rt_runtime;
790         sysctl_sched_rt_runtime = -1;
791 }
792 
793 static void rcu_torture_enable_rt_throttle(void)
794 {
795         if (!IS_BUILTIN(CONFIG_RCU_TORTURE_TEST) || old_rt_runtime == -1)
796                 return;
797 
798         sysctl_sched_rt_runtime = old_rt_runtime;
799         old_rt_runtime = -1;
800 }
801 
802 static bool rcu_torture_boost_failed(unsigned long start, unsigned long end)
803 {
804         if (end - start > test_boost_duration * HZ - HZ / 2) {
805                 VERBOSE_TOROUT_STRING("rcu_torture_boost boosting failed");
806                 n_rcu_torture_boost_failure++;
807 
808                 return true; /* failed */
809         }
810 
811         return false; /* passed */
812 }
813 
814 static int rcu_torture_boost(void *arg)
815 {
816         unsigned long call_rcu_time;
817         unsigned long endtime;
818         unsigned long oldstarttime;
819         struct rcu_boost_inflight rbi = { .inflight = 0 };
820         struct sched_param sp;
821 
822         VERBOSE_TOROUT_STRING("rcu_torture_boost started");
823 
824         /* Set real-time priority. */
825         sp.sched_priority = 1;
826         if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
827                 VERBOSE_TOROUT_STRING("rcu_torture_boost RT prio failed!");
828                 n_rcu_torture_boost_rterror++;
829         }
830 
831         init_rcu_head_on_stack(&rbi.rcu);
832         /* Each pass through the following loop does one boost-test cycle. */
833         do {
834                 /* Track if the test failed already in this test interval? */
835                 bool failed = false;
836 
837                 /* Increment n_rcu_torture_boosts once per boost-test */
838                 while (!kthread_should_stop()) {
839                         if (mutex_trylock(&boost_mutex)) {
840                                 n_rcu_torture_boosts++;
841                                 mutex_unlock(&boost_mutex);
842                                 break;
843                         }
844                         schedule_timeout_uninterruptible(1);
845                 }
846                 if (kthread_should_stop())
847                         goto checkwait;
848 
849                 /* Wait for the next test interval. */
850                 oldstarttime = boost_starttime;
851                 while (ULONG_CMP_LT(jiffies, oldstarttime)) {
852                         schedule_timeout_interruptible(oldstarttime - jiffies);
853                         stutter_wait("rcu_torture_boost");
854                         if (torture_must_stop())
855                                 goto checkwait;
856                 }
857 
858                 /* Do one boost-test interval. */
859                 endtime = oldstarttime + test_boost_duration * HZ;
860                 call_rcu_time = jiffies;
861                 while (ULONG_CMP_LT(jiffies, endtime)) {
862                         /* If we don't have a callback in flight, post one. */
863                         if (!smp_load_acquire(&rbi.inflight)) {
864                                 /* RCU core before ->inflight = 1. */
865                                 smp_store_release(&rbi.inflight, 1);
866                                 call_rcu(&rbi.rcu, rcu_torture_boost_cb);
867                                 /* Check if the boost test failed */
868                                 failed = failed ||
869                                          rcu_torture_boost_failed(call_rcu_time,
870                                                                  jiffies);
871                                 call_rcu_time = jiffies;
872                         }
873                         stutter_wait("rcu_torture_boost");
874                         if (torture_must_stop())
875                                 goto checkwait;
876                 }
877 
878                 /*
879                  * If boost never happened, then inflight will always be 1, in
880                  * this case the boost check would never happen in the above
881                  * loop so do another one here.
882                  */
883                 if (!failed && smp_load_acquire(&rbi.inflight))
884                         rcu_torture_boost_failed(call_rcu_time, jiffies);
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                                 mutex_unlock(&boost_mutex);
899                                 break;
900                         }
901                         schedule_timeout_uninterruptible(1);
902                 }
903 
904                 /* Go do the stutter. */
905 checkwait:      stutter_wait("rcu_torture_boost");
906         } while (!torture_must_stop());
907 
908         /* Clean up and exit. */
909         while (!kthread_should_stop() || smp_load_acquire(&rbi.inflight)) {
910                 torture_shutdown_absorb("rcu_torture_boost");
911                 schedule_timeout_uninterruptible(1);
912         }
913         destroy_rcu_head_on_stack(&rbi.rcu);
914         torture_kthread_stopping("rcu_torture_boost");
915         return 0;
916 }
917 
918 static void rcu_torture_cbflood_cb(struct rcu_head *rhp)
919 {
920 }
921 
922 /*
923  * RCU torture callback-flood kthread.  Repeatedly induces bursts of calls
924  * to call_rcu() or analogous, increasing the probability of occurrence
925  * of callback-overflow corner cases.
926  */
927 static int
928 rcu_torture_cbflood(void *arg)
929 {
930         int err = 1;
931         int i;
932         int j;
933         struct rcu_head *rhp;
934 
935         if (cbflood_n_per_burst > 0 &&
936             cbflood_inter_holdoff > 0 &&
937             cbflood_intra_holdoff > 0 &&
938             cur_ops->call &&
939             cur_ops->cb_barrier) {
940                 rhp = vmalloc(array3_size(cbflood_n_burst,
941                                           cbflood_n_per_burst,
942                                           sizeof(*rhp)));
943                 err = !rhp;
944         }
945         if (err) {
946                 VERBOSE_TOROUT_STRING("rcu_torture_cbflood disabled: Bad args or OOM");
947                 goto wait_for_stop;
948         }
949         VERBOSE_TOROUT_STRING("rcu_torture_cbflood task started");
950         do {
951                 schedule_timeout_interruptible(cbflood_inter_holdoff);
952                 atomic_long_inc(&n_cbfloods);
953                 WARN_ON(signal_pending(current));
954                 for (i = 0; i < cbflood_n_burst; i++) {
955                         for (j = 0; j < cbflood_n_per_burst; j++) {
956                                 cur_ops->call(&rhp[i * cbflood_n_per_burst + j],
957                                               rcu_torture_cbflood_cb);
958                         }
959                         schedule_timeout_interruptible(cbflood_intra_holdoff);
960                         WARN_ON(signal_pending(current));
961                 }
962                 cur_ops->cb_barrier();
963                 stutter_wait("rcu_torture_cbflood");
964         } while (!torture_must_stop());
965         vfree(rhp);
966 wait_for_stop:
967         torture_kthread_stopping("rcu_torture_cbflood");
968         return 0;
969 }
970 
971 /*
972  * RCU torture force-quiescent-state kthread.  Repeatedly induces
973  * bursts of calls to force_quiescent_state(), increasing the probability
974  * of occurrence of some important types of race conditions.
975  */
976 static int
977 rcu_torture_fqs(void *arg)
978 {
979         unsigned long fqs_resume_time;
980         int fqs_burst_remaining;
981 
982         VERBOSE_TOROUT_STRING("rcu_torture_fqs task started");
983         do {
984                 fqs_resume_time = jiffies + fqs_stutter * HZ;
985                 while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
986                        !kthread_should_stop()) {
987                         schedule_timeout_interruptible(1);
988                 }
989                 fqs_burst_remaining = fqs_duration;
990                 while (fqs_burst_remaining > 0 &&
991                        !kthread_should_stop()) {
992                         cur_ops->fqs();
993                         udelay(fqs_holdoff);
994                         fqs_burst_remaining -= fqs_holdoff;
995                 }
996                 stutter_wait("rcu_torture_fqs");
997         } while (!torture_must_stop());
998         torture_kthread_stopping("rcu_torture_fqs");
999         return 0;
1000 }
1001 
1002 /*
1003  * RCU torture writer kthread.  Repeatedly substitutes a new structure
1004  * for that pointed to by rcu_torture_current, freeing the old structure
1005  * after a series of grace periods (the "pipeline").
1006  */
1007 static int
1008 rcu_torture_writer(void *arg)
1009 {
1010         bool can_expedite = !rcu_gp_is_expedited() && !rcu_gp_is_normal();
1011         int expediting = 0;
1012         unsigned long gp_snap;
1013         bool gp_cond1 = gp_cond, gp_exp1 = gp_exp, gp_normal1 = gp_normal;
1014         bool gp_sync1 = gp_sync;
1015         int i;
1016         struct rcu_torture *rp;
1017         struct rcu_torture *old_rp;
1018         static DEFINE_TORTURE_RANDOM(rand);
1019         int synctype[] = { RTWS_DEF_FREE, RTWS_EXP_SYNC,
1020                            RTWS_COND_GET, RTWS_SYNC };
1021         int nsynctypes = 0;
1022 
1023         VERBOSE_TOROUT_STRING("rcu_torture_writer task started");
1024         if (!can_expedite)
1025                 pr_alert("%s" TORTURE_FLAG
1026                          " GP expediting controlled from boot/sysfs for %s.\n",
1027                          torture_type, cur_ops->name);
1028 
1029         /* Initialize synctype[] array.  If none set, take default. */
1030         if (!gp_cond1 && !gp_exp1 && !gp_normal1 && !gp_sync1)
1031                 gp_cond1 = gp_exp1 = gp_normal1 = gp_sync1 = true;
1032         if (gp_cond1 && cur_ops->get_state && cur_ops->cond_sync) {
1033                 synctype[nsynctypes++] = RTWS_COND_GET;
1034                 pr_info("%s: Testing conditional GPs.\n", __func__);
1035         } else if (gp_cond && (!cur_ops->get_state || !cur_ops->cond_sync)) {
1036                 pr_alert("%s: gp_cond without primitives.\n", __func__);
1037         }
1038         if (gp_exp1 && cur_ops->exp_sync) {
1039                 synctype[nsynctypes++] = RTWS_EXP_SYNC;
1040                 pr_info("%s: Testing expedited GPs.\n", __func__);
1041         } else if (gp_exp && !cur_ops->exp_sync) {
1042                 pr_alert("%s: gp_exp without primitives.\n", __func__);
1043         }
1044         if (gp_normal1 && cur_ops->deferred_free) {
1045                 synctype[nsynctypes++] = RTWS_DEF_FREE;
1046                 pr_info("%s: Testing asynchronous GPs.\n", __func__);
1047         } else if (gp_normal && !cur_ops->deferred_free) {
1048                 pr_alert("%s: gp_normal without primitives.\n", __func__);
1049         }
1050         if (gp_sync1 && cur_ops->sync) {
1051                 synctype[nsynctypes++] = RTWS_SYNC;
1052                 pr_info("%s: Testing normal GPs.\n", __func__);
1053         } else if (gp_sync && !cur_ops->sync) {
1054                 pr_alert("%s: gp_sync without primitives.\n", __func__);
1055         }
1056         if (WARN_ONCE(nsynctypes == 0,
1057                       "rcu_torture_writer: No update-side primitives.\n")) {
1058                 /*
1059                  * No updates primitives, so don't try updating.
1060                  * The resulting test won't be testing much, hence the
1061                  * above WARN_ONCE().
1062                  */
1063                 rcu_torture_writer_state = RTWS_STOPPING;
1064                 torture_kthread_stopping("rcu_torture_writer");
1065         }
1066 
1067         do {
1068                 rcu_torture_writer_state = RTWS_FIXED_DELAY;
1069                 schedule_timeout_uninterruptible(1);
1070                 rp = rcu_torture_alloc();
1071                 if (rp == NULL)
1072                         continue;
1073                 rp->rtort_pipe_count = 0;
1074                 rcu_torture_writer_state = RTWS_DELAY;
1075                 udelay(torture_random(&rand) & 0x3ff);
1076                 rcu_torture_writer_state = RTWS_REPLACE;
1077                 old_rp = rcu_dereference_check(rcu_torture_current,
1078                                                current == writer_task);
1079                 rp->rtort_mbtest = 1;
1080                 rcu_assign_pointer(rcu_torture_current, rp);
1081                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
1082                 if (old_rp) {
1083                         i = old_rp->rtort_pipe_count;
1084                         if (i > RCU_TORTURE_PIPE_LEN)
1085                                 i = RCU_TORTURE_PIPE_LEN;
1086                         atomic_inc(&rcu_torture_wcount[i]);
1087                         old_rp->rtort_pipe_count++;
1088                         switch (synctype[torture_random(&rand) % nsynctypes]) {
1089                         case RTWS_DEF_FREE:
1090                                 rcu_torture_writer_state = RTWS_DEF_FREE;
1091                                 cur_ops->deferred_free(old_rp);
1092                                 break;
1093                         case RTWS_EXP_SYNC:
1094                                 rcu_torture_writer_state = RTWS_EXP_SYNC;
1095                                 cur_ops->exp_sync();
1096                                 rcu_torture_pipe_update(old_rp);
1097                                 break;
1098                         case RTWS_COND_GET:
1099                                 rcu_torture_writer_state = RTWS_COND_GET;
1100                                 gp_snap = cur_ops->get_state();
1101                                 i = torture_random(&rand) % 16;
1102                                 if (i != 0)
1103                                         schedule_timeout_interruptible(i);
1104                                 udelay(torture_random(&rand) % 1000);
1105                                 rcu_torture_writer_state = RTWS_COND_SYNC;
1106                                 cur_ops->cond_sync(gp_snap);
1107                                 rcu_torture_pipe_update(old_rp);
1108                                 break;
1109                         case RTWS_SYNC:
1110                                 rcu_torture_writer_state = RTWS_SYNC;
1111                                 cur_ops->sync();
1112                                 rcu_torture_pipe_update(old_rp);
1113                                 break;
1114                         default:
1115                                 WARN_ON_ONCE(1);
1116                                 break;
1117                         }
1118                 }
1119                 rcu_torture_current_version++;
1120                 /* Cycle through nesting levels of rcu_expedite_gp() calls. */
1121                 if (can_expedite &&
1122                     !(torture_random(&rand) & 0xff & (!!expediting - 1))) {
1123                         WARN_ON_ONCE(expediting == 0 && rcu_gp_is_expedited());
1124                         if (expediting >= 0)
1125                                 rcu_expedite_gp();
1126                         else
1127                                 rcu_unexpedite_gp();
1128                         if (++expediting > 3)
1129                                 expediting = -expediting;
1130                 } else if (!can_expedite) { /* Disabled during boot, recheck. */
1131                         can_expedite = !rcu_gp_is_expedited() &&
1132                                        !rcu_gp_is_normal();
1133                 }
1134                 rcu_torture_writer_state = RTWS_STUTTER;
1135                 stutter_wait("rcu_torture_writer");
1136         } while (!torture_must_stop());
1137         /* Reset expediting back to unexpedited. */
1138         if (expediting > 0)
1139                 expediting = -expediting;
1140         while (can_expedite && expediting++ < 0)
1141                 rcu_unexpedite_gp();
1142         WARN_ON_ONCE(can_expedite && rcu_gp_is_expedited());
1143         if (!can_expedite)
1144                 pr_alert("%s" TORTURE_FLAG
1145                          " Dynamic grace-period expediting was disabled.\n",
1146                          torture_type);
1147         rcu_torture_writer_state = RTWS_STOPPING;
1148         torture_kthread_stopping("rcu_torture_writer");
1149         return 0;
1150 }
1151 
1152 /*
1153  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
1154  * delay between calls.
1155  */
1156 static int
1157 rcu_torture_fakewriter(void *arg)
1158 {
1159         DEFINE_TORTURE_RANDOM(rand);
1160 
1161         VERBOSE_TOROUT_STRING("rcu_torture_fakewriter task started");
1162         set_user_nice(current, MAX_NICE);
1163 
1164         do {
1165                 schedule_timeout_uninterruptible(1 + torture_random(&rand)%10);
1166                 udelay(torture_random(&rand) & 0x3ff);
1167                 if (cur_ops->cb_barrier != NULL &&
1168                     torture_random(&rand) % (nfakewriters * 8) == 0) {
1169                         cur_ops->cb_barrier();
1170                 } else if (gp_normal == gp_exp) {
1171                         if (cur_ops->sync && torture_random(&rand) & 0x80)
1172                                 cur_ops->sync();
1173                         else if (cur_ops->exp_sync)
1174                                 cur_ops->exp_sync();
1175                 } else if (gp_normal && cur_ops->sync) {
1176                         cur_ops->sync();
1177                 } else if (cur_ops->exp_sync) {
1178                         cur_ops->exp_sync();
1179                 }
1180                 stutter_wait("rcu_torture_fakewriter");
1181         } while (!torture_must_stop());
1182 
1183         torture_kthread_stopping("rcu_torture_fakewriter");
1184         return 0;
1185 }
1186 
1187 static void rcu_torture_timer_cb(struct rcu_head *rhp)
1188 {
1189         kfree(rhp);
1190 }
1191 
1192 /*
1193  * Do one extension of an RCU read-side critical section using the
1194  * current reader state in readstate (set to zero for initial entry
1195  * to extended critical section), set the new state as specified by
1196  * newstate (set to zero for final exit from extended critical section),
1197  * and random-number-generator state in trsp.  If this is neither the
1198  * beginning or end of the critical section and if there was actually a
1199  * change, do a ->read_delay().
1200  */
1201 static void rcutorture_one_extend(int *readstate, int newstate,
1202                                   struct torture_random_state *trsp)
1203 {
1204         int idxnew = -1;
1205         int idxold = *readstate;
1206         int statesnew = ~*readstate & newstate;
1207         int statesold = *readstate & ~newstate;
1208 
1209         WARN_ON_ONCE(idxold < 0);
1210         WARN_ON_ONCE((idxold >> RCUTORTURE_RDR_SHIFT) > 1);
1211 
1212         /* First, put new protection in place to avoid critical-section gap. */
1213         if (statesnew & RCUTORTURE_RDR_BH)
1214                 local_bh_disable();
1215         if (statesnew & RCUTORTURE_RDR_IRQ)
1216                 local_irq_disable();
1217         if (statesnew & RCUTORTURE_RDR_PREEMPT)
1218                 preempt_disable();
1219         if (statesnew & RCUTORTURE_RDR_RCU)
1220                 idxnew = cur_ops->readlock() << RCUTORTURE_RDR_SHIFT;
1221 
1222         /* Next, remove old protection, irq first due to bh conflict. */
1223         if (statesold & RCUTORTURE_RDR_IRQ)
1224                 local_irq_enable();
1225         if (statesold & RCUTORTURE_RDR_BH)
1226                 local_bh_enable();
1227         if (statesold & RCUTORTURE_RDR_PREEMPT)
1228                 preempt_enable();
1229         if (statesold & RCUTORTURE_RDR_RCU)
1230                 cur_ops->readunlock(idxold >> RCUTORTURE_RDR_SHIFT);
1231 
1232         /* Delay if neither beginning nor end and there was a change. */
1233         if ((statesnew || statesold) && *readstate && newstate)
1234                 cur_ops->read_delay(trsp);
1235 
1236         /* Update the reader state. */
1237         if (idxnew == -1)
1238                 idxnew = idxold & ~RCUTORTURE_RDR_MASK;
1239         WARN_ON_ONCE(idxnew < 0);
1240         WARN_ON_ONCE((idxnew >> RCUTORTURE_RDR_SHIFT) > 1);
1241         *readstate = idxnew | newstate;
1242         WARN_ON_ONCE((*readstate >> RCUTORTURE_RDR_SHIFT) < 0);
1243         WARN_ON_ONCE((*readstate >> RCUTORTURE_RDR_SHIFT) > 1);
1244 }
1245 
1246 /* Return the biggest extendables mask given current RCU and boot parameters. */
1247 static int rcutorture_extend_mask_max(void)
1248 {
1249         int mask;
1250 
1251         WARN_ON_ONCE(extendables & ~RCUTORTURE_MAX_EXTEND);
1252         mask = extendables & RCUTORTURE_MAX_EXTEND & cur_ops->extendables;
1253         mask = mask | RCUTORTURE_RDR_RCU;
1254         return mask;
1255 }
1256 
1257 /* Return a random protection state mask, but with at least one bit set. */
1258 static int
1259 rcutorture_extend_mask(int oldmask, struct torture_random_state *trsp)
1260 {
1261         int mask = rcutorture_extend_mask_max();
1262         unsigned long randmask1 = torture_random(trsp) >> 8;
1263         unsigned long randmask2 = randmask1 >> 1;
1264 
1265         WARN_ON_ONCE(mask >> RCUTORTURE_RDR_SHIFT);
1266         /* Half the time lots of bits, half the time only one bit. */
1267         if (randmask1 & 0x1)
1268                 mask = mask & randmask2;
1269         else
1270                 mask = mask & (1 << (randmask2 % RCUTORTURE_RDR_NBITS));
1271         if ((mask & RCUTORTURE_RDR_IRQ) &&
1272             !(mask & RCUTORTURE_RDR_BH) &&
1273             (oldmask & RCUTORTURE_RDR_BH))
1274                 mask |= RCUTORTURE_RDR_BH; /* Can't enable bh w/irq disabled. */
1275         if ((mask & RCUTORTURE_RDR_IRQ) &&
1276             !(mask & cur_ops->ext_irq_conflict) &&
1277             (oldmask & cur_ops->ext_irq_conflict))
1278                 mask |= cur_ops->ext_irq_conflict; /* Or if readers object. */
1279         return mask ?: RCUTORTURE_RDR_RCU;
1280 }
1281 
1282 /*
1283  * Do a randomly selected number of extensions of an existing RCU read-side
1284  * critical section.
1285  */
1286 static void rcutorture_loop_extend(int *readstate,
1287                                    struct torture_random_state *trsp)
1288 {
1289         int i;
1290         int mask = rcutorture_extend_mask_max();
1291 
1292         WARN_ON_ONCE(!*readstate); /* -Existing- RCU read-side critsect! */
1293         if (!((mask - 1) & mask))
1294                 return;  /* Current RCU flavor not extendable. */
1295         i = (torture_random(trsp) >> 3) & RCUTORTURE_RDR_MAX_LOOPS;
1296         while (i--) {
1297                 mask = rcutorture_extend_mask(*readstate, trsp);
1298                 rcutorture_one_extend(readstate, mask, trsp);
1299         }
1300 }
1301 
1302 /*
1303  * Do one read-side critical section, returning false if there was
1304  * no data to read.  Can be invoked both from process context and
1305  * from a timer handler.
1306  */
1307 static bool rcu_torture_one_read(struct torture_random_state *trsp)
1308 {
1309         unsigned long started;
1310         unsigned long completed;
1311         int newstate;
1312         struct rcu_torture *p;
1313         int pipe_count;
1314         int readstate = 0;
1315         unsigned long long ts;
1316 
1317         newstate = rcutorture_extend_mask(readstate, trsp);
1318         rcutorture_one_extend(&readstate, newstate, trsp);
1319         started = cur_ops->get_gp_seq();
1320         ts = rcu_trace_clock_local();
1321         p = rcu_dereference_check(rcu_torture_current,
1322                                   rcu_read_lock_bh_held() ||
1323                                   rcu_read_lock_sched_held() ||
1324                                   srcu_read_lock_held(srcu_ctlp) ||
1325                                   torturing_tasks());
1326         if (p == NULL) {
1327                 /* Wait for rcu_torture_writer to get underway */
1328                 rcutorture_one_extend(&readstate, 0, trsp);
1329                 return false;
1330         }
1331         if (p->rtort_mbtest == 0)
1332                 atomic_inc(&n_rcu_torture_mberror);
1333         rcutorture_loop_extend(&readstate, trsp);
1334         preempt_disable();
1335         pipe_count = p->rtort_pipe_count;
1336         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1337                 /* Should not happen, but... */
1338                 pipe_count = RCU_TORTURE_PIPE_LEN;
1339         }
1340         completed = cur_ops->get_gp_seq();
1341         if (pipe_count > 1) {
1342                 do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
1343                                           ts, started, completed);
1344                 rcu_ftrace_dump(DUMP_ALL);
1345         }
1346         __this_cpu_inc(rcu_torture_count[pipe_count]);
1347         completed = rcutorture_seq_diff(completed, started);
1348         if (completed > RCU_TORTURE_PIPE_LEN) {
1349                 /* Should not happen, but... */
1350                 completed = RCU_TORTURE_PIPE_LEN;
1351         }
1352         __this_cpu_inc(rcu_torture_batch[completed]);
1353         preempt_enable();
1354         rcutorture_one_extend(&readstate, 0, trsp);
1355         WARN_ON_ONCE(readstate & RCUTORTURE_RDR_MASK);
1356         return true;
1357 }
1358 
1359 static DEFINE_TORTURE_RANDOM_PERCPU(rcu_torture_timer_rand);
1360 
1361 /*
1362  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
1363  * incrementing the corresponding element of the pipeline array.  The
1364  * counter in the element should never be greater than 1, otherwise, the
1365  * RCU implementation is broken.
1366  */
1367 static void rcu_torture_timer(struct timer_list *unused)
1368 {
1369         atomic_long_inc(&n_rcu_torture_timers);
1370         (void)rcu_torture_one_read(this_cpu_ptr(&rcu_torture_timer_rand));
1371 
1372         /* Test call_rcu() invocation from interrupt handler. */
1373         if (cur_ops->call) {
1374                 struct rcu_head *rhp = kmalloc(sizeof(*rhp), GFP_NOWAIT);
1375 
1376                 if (rhp)
1377                         cur_ops->call(rhp, rcu_torture_timer_cb);
1378         }
1379 }
1380 
1381 /*
1382  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
1383  * incrementing the corresponding element of the pipeline array.  The
1384  * counter in the element should never be greater than 1, otherwise, the
1385  * RCU implementation is broken.
1386  */
1387 static int
1388 rcu_torture_reader(void *arg)
1389 {
1390         DEFINE_TORTURE_RANDOM(rand);
1391         struct timer_list t;
1392 
1393         VERBOSE_TOROUT_STRING("rcu_torture_reader task started");
1394         set_user_nice(current, MAX_NICE);
1395         if (irqreader && cur_ops->irq_capable)
1396                 timer_setup_on_stack(&t, rcu_torture_timer, 0);
1397 
1398         do {
1399                 if (irqreader && cur_ops->irq_capable) {
1400                         if (!timer_pending(&t))
1401                                 mod_timer(&t, jiffies + 1);
1402                 }
1403                 if (!rcu_torture_one_read(&rand))
1404                         schedule_timeout_interruptible(HZ);
1405                 stutter_wait("rcu_torture_reader");
1406         } while (!torture_must_stop());
1407         if (irqreader && cur_ops->irq_capable) {
1408                 del_timer_sync(&t);
1409                 destroy_timer_on_stack(&t);
1410         }
1411         torture_kthread_stopping("rcu_torture_reader");
1412         return 0;
1413 }
1414 
1415 /*
1416  * Print torture statistics.  Caller must ensure that there is only
1417  * one call to this function at a given time!!!  This is normally
1418  * accomplished by relying on the module system to only have one copy
1419  * of the module loaded, and then by giving the rcu_torture_stats
1420  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1421  * thread is not running).
1422  */
1423 static void
1424 rcu_torture_stats_print(void)
1425 {
1426         int cpu;
1427         int i;
1428         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1429         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1430         static unsigned long rtcv_snap = ULONG_MAX;
1431         static bool splatted;
1432         struct task_struct *wtp;
1433 
1434         for_each_possible_cpu(cpu) {
1435                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1436                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1437                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1438                 }
1439         }
1440         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1441                 if (pipesummary[i] != 0)
1442                         break;
1443         }
1444 
1445         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1446         pr_cont("rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
1447                 rcu_torture_current,
1448                 rcu_torture_current_version,
1449                 list_empty(&rcu_torture_freelist),
1450                 atomic_read(&n_rcu_torture_alloc),
1451                 atomic_read(&n_rcu_torture_alloc_fail),
1452                 atomic_read(&n_rcu_torture_free));
1453         pr_cont("rtmbe: %d rtbe: %ld rtbke: %ld rtbre: %ld ",
1454                 atomic_read(&n_rcu_torture_mberror),
1455                 n_rcu_torture_barrier_error,
1456                 n_rcu_torture_boost_ktrerror,
1457                 n_rcu_torture_boost_rterror);
1458         pr_cont("rtbf: %ld rtb: %ld nt: %ld ",
1459                 n_rcu_torture_boost_failure,
1460                 n_rcu_torture_boosts,
1461                 atomic_long_read(&n_rcu_torture_timers));
1462         torture_onoff_stats();
1463         pr_cont("barrier: %ld/%ld:%ld ",
1464                 n_barrier_successes,
1465                 n_barrier_attempts,
1466                 n_rcu_torture_barrier_error);
1467         pr_cont("cbflood: %ld\n", atomic_long_read(&n_cbfloods));
1468 
1469         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1470         if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1471             n_rcu_torture_barrier_error != 0 ||
1472             n_rcu_torture_boost_ktrerror != 0 ||
1473             n_rcu_torture_boost_rterror != 0 ||
1474             n_rcu_torture_boost_failure != 0 ||
1475             i > 1) {
1476                 pr_cont("%s", "!!! ");
1477                 atomic_inc(&n_rcu_torture_error);
1478                 WARN_ON_ONCE(1);
1479         }
1480         pr_cont("Reader Pipe: ");
1481         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1482                 pr_cont(" %ld", pipesummary[i]);
1483         pr_cont("\n");
1484 
1485         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1486         pr_cont("Reader Batch: ");
1487         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1488                 pr_cont(" %ld", batchsummary[i]);
1489         pr_cont("\n");
1490 
1491         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1492         pr_cont("Free-Block Circulation: ");
1493         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1494                 pr_cont(" %d", atomic_read(&rcu_torture_wcount[i]));
1495         }
1496         pr_cont("\n");
1497 
1498         if (cur_ops->stats)
1499                 cur_ops->stats();
1500         if (rtcv_snap == rcu_torture_current_version &&
1501             rcu_torture_current != NULL) {
1502                 int __maybe_unused flags = 0;
1503                 unsigned long __maybe_unused gp_seq = 0;
1504 
1505                 rcutorture_get_gp_data(cur_ops->ttype,
1506                                        &flags, &gp_seq);
1507                 srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp,
1508                                         &flags, &gp_seq);
1509                 wtp = READ_ONCE(writer_task);
1510                 pr_alert("??? Writer stall state %s(%d) g%lu f%#x ->state %#lx cpu %d\n",
1511                          rcu_torture_writer_state_getname(),
1512                          rcu_torture_writer_state, gp_seq, flags,
1513                          wtp == NULL ? ~0UL : wtp->state,
1514                          wtp == NULL ? -1 : (int)task_cpu(wtp));
1515                 if (!splatted && wtp) {
1516                         sched_show_task(wtp);
1517                         splatted = true;
1518                 }
1519                 show_rcu_gp_kthreads();
1520                 rcu_ftrace_dump(DUMP_ALL);
1521         }
1522         rtcv_snap = rcu_torture_current_version;
1523 }
1524 
1525 /*
1526  * Periodically prints torture statistics, if periodic statistics printing
1527  * was specified via the stat_interval module parameter.
1528  */
1529 static int
1530 rcu_torture_stats(void *arg)
1531 {
1532         VERBOSE_TOROUT_STRING("rcu_torture_stats task started");
1533         do {
1534                 schedule_timeout_interruptible(stat_interval * HZ);
1535                 rcu_torture_stats_print();
1536                 torture_shutdown_absorb("rcu_torture_stats");
1537         } while (!torture_must_stop());
1538         torture_kthread_stopping("rcu_torture_stats");
1539         return 0;
1540 }
1541 
1542 static void
1543 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
1544 {
1545         pr_alert("%s" TORTURE_FLAG
1546                  "--- %s: nreaders=%d nfakewriters=%d "
1547                  "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1548                  "shuffle_interval=%d stutter=%d irqreader=%d "
1549                  "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1550                  "test_boost=%d/%d test_boost_interval=%d "
1551                  "test_boost_duration=%d shutdown_secs=%d "
1552                  "stall_cpu=%d stall_cpu_holdoff=%d stall_cpu_irqsoff=%d "
1553                  "n_barrier_cbs=%d "
1554                  "onoff_interval=%d onoff_holdoff=%d\n",
1555                  torture_type, tag, nrealreaders, nfakewriters,
1556                  stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1557                  stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1558                  test_boost, cur_ops->can_boost,
1559                  test_boost_interval, test_boost_duration, shutdown_secs,
1560                  stall_cpu, stall_cpu_holdoff, stall_cpu_irqsoff,
1561                  n_barrier_cbs,
1562                  onoff_interval, onoff_holdoff);
1563 }
1564 
1565 static int rcutorture_booster_cleanup(unsigned int cpu)
1566 {
1567         struct task_struct *t;
1568 
1569         if (boost_tasks[cpu] == NULL)
1570                 return 0;
1571         mutex_lock(&boost_mutex);
1572         t = boost_tasks[cpu];
1573         boost_tasks[cpu] = NULL;
1574         rcu_torture_enable_rt_throttle();
1575         mutex_unlock(&boost_mutex);
1576 
1577         /* This must be outside of the mutex, otherwise deadlock! */
1578         torture_stop_kthread(rcu_torture_boost, t);
1579         return 0;
1580 }
1581 
1582 static int rcutorture_booster_init(unsigned int cpu)
1583 {
1584         int retval;
1585 
1586         if (boost_tasks[cpu] != NULL)
1587                 return 0;  /* Already created, nothing more to do. */
1588 
1589         /* Don't allow time recalculation while creating a new task. */
1590         mutex_lock(&boost_mutex);
1591         rcu_torture_disable_rt_throttle();
1592         VERBOSE_TOROUT_STRING("Creating rcu_torture_boost task");
1593         boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1594                                                   cpu_to_node(cpu),
1595                                                   "rcu_torture_boost");
1596         if (IS_ERR(boost_tasks[cpu])) {
1597                 retval = PTR_ERR(boost_tasks[cpu]);
1598                 VERBOSE_TOROUT_STRING("rcu_torture_boost task create failed");
1599                 n_rcu_torture_boost_ktrerror++;
1600                 boost_tasks[cpu] = NULL;
1601                 mutex_unlock(&boost_mutex);
1602                 return retval;
1603         }
1604         kthread_bind(boost_tasks[cpu], cpu);
1605         wake_up_process(boost_tasks[cpu]);
1606         mutex_unlock(&boost_mutex);
1607         return 0;
1608 }
1609 
1610 /*
1611  * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
1612  * induces a CPU stall for the time specified by stall_cpu.
1613  */
1614 static int rcu_torture_stall(void *args)
1615 {
1616         unsigned long stop_at;
1617 
1618         VERBOSE_TOROUT_STRING("rcu_torture_stall task started");
1619         if (stall_cpu_holdoff > 0) {
1620                 VERBOSE_TOROUT_STRING("rcu_torture_stall begin holdoff");
1621                 schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1622                 VERBOSE_TOROUT_STRING("rcu_torture_stall end holdoff");
1623         }
1624         if (!kthread_should_stop()) {
1625                 stop_at = ktime_get_seconds() + stall_cpu;
1626                 /* RCU CPU stall is expected behavior in following code. */
1627                 rcu_read_lock();
1628                 if (stall_cpu_irqsoff)
1629                         local_irq_disable();
1630                 else
1631                         preempt_disable();
1632                 pr_alert("rcu_torture_stall start on CPU %d.\n",
1633                          smp_processor_id());
1634                 while (ULONG_CMP_LT((unsigned long)ktime_get_seconds(),
1635                                     stop_at))
1636                         continue;  /* Induce RCU CPU stall warning. */
1637                 if (stall_cpu_irqsoff)
1638                         local_irq_enable();
1639                 else
1640                         preempt_enable();
1641                 rcu_read_unlock();
1642                 pr_alert("rcu_torture_stall end.\n");
1643         }
1644         torture_shutdown_absorb("rcu_torture_stall");
1645         while (!kthread_should_stop())
1646                 schedule_timeout_interruptible(10 * HZ);
1647         return 0;
1648 }
1649 
1650 /* Spawn CPU-stall kthread, if stall_cpu specified. */
1651 static int __init rcu_torture_stall_init(void)
1652 {
1653         if (stall_cpu <= 0)
1654                 return 0;
1655         return torture_create_kthread(rcu_torture_stall, NULL, stall_task);
1656 }
1657 
1658 /* Callback function for RCU barrier testing. */
1659 static void rcu_torture_barrier_cbf(struct rcu_head *rcu)
1660 {
1661         atomic_inc(&barrier_cbs_invoked);
1662 }
1663 
1664 /* kthread function to register callbacks used to test RCU barriers. */
1665 static int rcu_torture_barrier_cbs(void *arg)
1666 {
1667         long myid = (long)arg;
1668         bool lastphase = 0;
1669         bool newphase;
1670         struct rcu_head rcu;
1671 
1672         init_rcu_head_on_stack(&rcu);
1673         VERBOSE_TOROUT_STRING("rcu_torture_barrier_cbs task started");
1674         set_user_nice(current, MAX_NICE);
1675         do {
1676                 wait_event(barrier_cbs_wq[myid],
1677                            (newphase =
1678                             smp_load_acquire(&barrier_phase)) != lastphase ||
1679                            torture_must_stop());
1680                 lastphase = newphase;
1681                 if (torture_must_stop())
1682                         break;
1683                 /*
1684                  * The above smp_load_acquire() ensures barrier_phase load
1685                  * is ordered before the following ->call().
1686                  */
1687                 local_irq_disable(); /* Just to test no-irq call_rcu(). */
1688                 cur_ops->call(&rcu, rcu_torture_barrier_cbf);
1689                 local_irq_enable();
1690                 if (atomic_dec_and_test(&barrier_cbs_count))
1691                         wake_up(&barrier_wq);
1692         } while (!torture_must_stop());
1693         if (cur_ops->cb_barrier != NULL)
1694                 cur_ops->cb_barrier();
1695         destroy_rcu_head_on_stack(&rcu);
1696         torture_kthread_stopping("rcu_torture_barrier_cbs");
1697         return 0;
1698 }
1699 
1700 /* kthread function to drive and coordinate RCU barrier testing. */
1701 static int rcu_torture_barrier(void *arg)
1702 {
1703         int i;
1704 
1705         VERBOSE_TOROUT_STRING("rcu_torture_barrier task starting");
1706         do {
1707                 atomic_set(&barrier_cbs_invoked, 0);
1708                 atomic_set(&barrier_cbs_count, n_barrier_cbs);
1709                 /* Ensure barrier_phase ordered after prior assignments. */
1710                 smp_store_release(&barrier_phase, !barrier_phase);
1711                 for (i = 0; i < n_barrier_cbs; i++)
1712                         wake_up(&barrier_cbs_wq[i]);
1713                 wait_event(barrier_wq,
1714                            atomic_read(&barrier_cbs_count) == 0 ||
1715                            torture_must_stop());
1716                 if (torture_must_stop())
1717                         break;
1718                 n_barrier_attempts++;
1719                 cur_ops->cb_barrier(); /* Implies smp_mb() for wait_event(). */
1720                 if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
1721                         n_rcu_torture_barrier_error++;
1722                         pr_err("barrier_cbs_invoked = %d, n_barrier_cbs = %d\n",
1723                                atomic_read(&barrier_cbs_invoked),
1724                                n_barrier_cbs);
1725                         WARN_ON_ONCE(1);
1726                 } else {
1727                         n_barrier_successes++;
1728                 }
1729                 schedule_timeout_interruptible(HZ / 10);
1730         } while (!torture_must_stop());
1731         torture_kthread_stopping("rcu_torture_barrier");
1732         return 0;
1733 }
1734 
1735 /* Initialize RCU barrier testing. */
1736 static int rcu_torture_barrier_init(void)
1737 {
1738         int i;
1739         int ret;
1740 
1741         if (n_barrier_cbs <= 0)
1742                 return 0;
1743         if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
1744                 pr_alert("%s" TORTURE_FLAG
1745                          " Call or barrier ops missing for %s,\n",
1746                          torture_type, cur_ops->name);
1747                 pr_alert("%s" TORTURE_FLAG
1748                          " RCU barrier testing omitted from run.\n",
1749                          torture_type);
1750                 return 0;
1751         }
1752         atomic_set(&barrier_cbs_count, 0);
1753         atomic_set(&barrier_cbs_invoked, 0);
1754         barrier_cbs_tasks =
1755                 kcalloc(n_barrier_cbs, sizeof(barrier_cbs_tasks[0]),
1756                         GFP_KERNEL);
1757         barrier_cbs_wq =
1758                 kcalloc(n_barrier_cbs, sizeof(barrier_cbs_wq[0]), GFP_KERNEL);
1759         if (barrier_cbs_tasks == NULL || !barrier_cbs_wq)
1760                 return -ENOMEM;
1761         for (i = 0; i < n_barrier_cbs; i++) {
1762                 init_waitqueue_head(&barrier_cbs_wq[i]);
1763                 ret = torture_create_kthread(rcu_torture_barrier_cbs,
1764                                              (void *)(long)i,
1765                                              barrier_cbs_tasks[i]);
1766                 if (ret)
1767                         return ret;
1768         }
1769         return torture_create_kthread(rcu_torture_barrier, NULL, barrier_task);
1770 }
1771 
1772 /* Clean up after RCU barrier testing. */
1773 static void rcu_torture_barrier_cleanup(void)
1774 {
1775         int i;
1776 
1777         torture_stop_kthread(rcu_torture_barrier, barrier_task);
1778         if (barrier_cbs_tasks != NULL) {
1779                 for (i = 0; i < n_barrier_cbs; i++)
1780                         torture_stop_kthread(rcu_torture_barrier_cbs,
1781                                              barrier_cbs_tasks[i]);
1782                 kfree(barrier_cbs_tasks);
1783                 barrier_cbs_tasks = NULL;
1784         }
1785         if (barrier_cbs_wq != NULL) {
1786                 kfree(barrier_cbs_wq);
1787                 barrier_cbs_wq = NULL;
1788         }
1789 }
1790 
1791 static bool rcu_torture_can_boost(void)
1792 {
1793         static int boost_warn_once;
1794         int prio;
1795 
1796         if (!(test_boost == 1 && cur_ops->can_boost) && test_boost != 2)
1797                 return false;
1798 
1799         prio = rcu_get_gp_kthreads_prio();
1800         if (!prio)
1801                 return false;
1802 
1803         if (prio < 2) {
1804                 if (boost_warn_once  == 1)
1805                         return false;
1806 
1807                 pr_alert("%s: WARN: RCU kthread priority too low to test boosting.  Skipping RCU boost test. Try passing rcutree.kthread_prio > 1 on the kernel command line.\n", KBUILD_MODNAME);
1808                 boost_warn_once = 1;
1809                 return false;
1810         }
1811 
1812         return true;
1813 }
1814 
1815 static enum cpuhp_state rcutor_hp;
1816 
1817 static void
1818 rcu_torture_cleanup(void)
1819 {
1820         int flags = 0;
1821         unsigned long gp_seq = 0;
1822         int i;
1823 
1824         if (torture_cleanup_begin()) {
1825                 if (cur_ops->cb_barrier != NULL)
1826                         cur_ops->cb_barrier();
1827                 return;
1828         }
1829 
1830         rcu_torture_barrier_cleanup();
1831         torture_stop_kthread(rcu_torture_stall, stall_task);
1832         torture_stop_kthread(rcu_torture_writer, writer_task);
1833 
1834         if (reader_tasks) {
1835                 for (i = 0; i < nrealreaders; i++)
1836                         torture_stop_kthread(rcu_torture_reader,
1837                                              reader_tasks[i]);
1838                 kfree(reader_tasks);
1839         }
1840         rcu_torture_current = NULL;
1841 
1842         if (fakewriter_tasks) {
1843                 for (i = 0; i < nfakewriters; i++) {
1844                         torture_stop_kthread(rcu_torture_fakewriter,
1845                                              fakewriter_tasks[i]);
1846                 }
1847                 kfree(fakewriter_tasks);
1848                 fakewriter_tasks = NULL;
1849         }
1850 
1851         rcutorture_get_gp_data(cur_ops->ttype, &flags, &gp_seq);
1852         srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp, &flags, &gp_seq);
1853         pr_alert("%s:  End-test grace-period state: g%lu f%#x\n",
1854                  cur_ops->name, gp_seq, flags);
1855         torture_stop_kthread(rcu_torture_stats, stats_task);
1856         torture_stop_kthread(rcu_torture_fqs, fqs_task);
1857         for (i = 0; i < ncbflooders; i++)
1858                 torture_stop_kthread(rcu_torture_cbflood, cbflood_task[i]);
1859         if (rcu_torture_can_boost())
1860                 cpuhp_remove_state(rcutor_hp);
1861 
1862         /*
1863          * Wait for all RCU callbacks to fire, then do flavor-specific
1864          * cleanup operations.
1865          */
1866         if (cur_ops->cb_barrier != NULL)
1867                 cur_ops->cb_barrier();
1868         if (cur_ops->cleanup != NULL)
1869                 cur_ops->cleanup();
1870 
1871         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1872 
1873         if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
1874                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1875         else if (torture_onoff_failures())
1876                 rcu_torture_print_module_parms(cur_ops,
1877                                                "End of test: RCU_HOTPLUG");
1878         else
1879                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1880         torture_cleanup_end();
1881 }
1882 
1883 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1884 static void rcu_torture_leak_cb(struct rcu_head *rhp)
1885 {
1886 }
1887 
1888 static void rcu_torture_err_cb(struct rcu_head *rhp)
1889 {
1890         /*
1891          * This -might- happen due to race conditions, but is unlikely.
1892          * The scenario that leads to this happening is that the
1893          * first of the pair of duplicate callbacks is queued,
1894          * someone else starts a grace period that includes that
1895          * callback, then the second of the pair must wait for the
1896          * next grace period.  Unlikely, but can happen.  If it
1897          * does happen, the debug-objects subsystem won't have splatted.
1898          */
1899         pr_alert("%s: duplicated callback was invoked.\n", KBUILD_MODNAME);
1900 }
1901 #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1902 
1903 /*
1904  * Verify that double-free causes debug-objects to complain, but only
1905  * if CONFIG_DEBUG_OBJECTS_RCU_HEAD=y.  Otherwise, say that the test
1906  * cannot be carried out.
1907  */
1908 static void rcu_test_debug_objects(void)
1909 {
1910 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1911         struct rcu_head rh1;
1912         struct rcu_head rh2;
1913 
1914         init_rcu_head_on_stack(&rh1);
1915         init_rcu_head_on_stack(&rh2);
1916         pr_alert("%s: WARN: Duplicate call_rcu() test starting.\n", KBUILD_MODNAME);
1917 
1918         /* Try to queue the rh2 pair of callbacks for the same grace period. */
1919         preempt_disable(); /* Prevent preemption from interrupting test. */
1920         rcu_read_lock(); /* Make it impossible to finish a grace period. */
1921         call_rcu(&rh1, rcu_torture_leak_cb); /* Start grace period. */
1922         local_irq_disable(); /* Make it harder to start a new grace period. */
1923         call_rcu(&rh2, rcu_torture_leak_cb);
1924         call_rcu(&rh2, rcu_torture_err_cb); /* Duplicate callback. */
1925         local_irq_enable();
1926         rcu_read_unlock();
1927         preempt_enable();
1928 
1929         /* Wait for them all to get done so we can safely return. */
1930         rcu_barrier();
1931         pr_alert("%s: WARN: Duplicate call_rcu() test complete.\n", KBUILD_MODNAME);
1932         destroy_rcu_head_on_stack(&rh1);
1933         destroy_rcu_head_on_stack(&rh2);
1934 #else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1935         pr_alert("%s: !CONFIG_DEBUG_OBJECTS_RCU_HEAD, not testing duplicate call_rcu()\n", KBUILD_MODNAME);
1936 #endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1937 }
1938 
1939 static int __init
1940 rcu_torture_init(void)
1941 {
1942         int i;
1943         int cpu;
1944         int firsterr = 0;
1945         static struct rcu_torture_ops *torture_ops[] = {
1946                 &rcu_ops, &rcu_bh_ops, &rcu_busted_ops, &srcu_ops, &srcud_ops,
1947                 &busted_srcud_ops, &sched_ops, &tasks_ops,
1948         };
1949 
1950         if (!torture_init_begin(torture_type, verbose))
1951                 return -EBUSY;
1952 
1953         /* Process args and tell the world that the torturer is on the job. */
1954         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1955                 cur_ops = torture_ops[i];
1956                 if (strcmp(torture_type, cur_ops->name) == 0)
1957                         break;
1958         }
1959         if (i == ARRAY_SIZE(torture_ops)) {
1960                 pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
1961                          torture_type);
1962                 pr_alert("rcu-torture types:");
1963                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1964                         pr_cont(" %s", torture_ops[i]->name);
1965                 pr_cont("\n");
1966                 firsterr = -EINVAL;
1967                 goto unwind;
1968         }
1969         if (cur_ops->fqs == NULL && fqs_duration != 0) {
1970                 pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
1971                 fqs_duration = 0;
1972         }
1973         if (cur_ops->init)
1974                 cur_ops->init();
1975 
1976         if (nreaders >= 0) {
1977                 nrealreaders = nreaders;
1978         } else {
1979                 nrealreaders = num_online_cpus() - 2 - nreaders;
1980                 if (nrealreaders <= 0)
1981                         nrealreaders = 1;
1982         }
1983         rcu_torture_print_module_parms(cur_ops, "Start of test");
1984 
1985         /* Set up the freelist. */
1986 
1987         INIT_LIST_HEAD(&rcu_torture_freelist);
1988         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1989                 rcu_tortures[i].rtort_mbtest = 0;
1990                 list_add_tail(&rcu_tortures[i].rtort_free,
1991                               &rcu_torture_freelist);
1992         }
1993 
1994         /* Initialize the statistics so that each run gets its own numbers. */
1995 
1996         rcu_torture_current = NULL;
1997         rcu_torture_current_version = 0;
1998         atomic_set(&n_rcu_torture_alloc, 0);
1999         atomic_set(&n_rcu_torture_alloc_fail, 0);
2000         atomic_set(&n_rcu_torture_free, 0);
2001         atomic_set(&n_rcu_torture_mberror, 0);
2002         atomic_set(&n_rcu_torture_error, 0);
2003         n_rcu_torture_barrier_error = 0;
2004         n_rcu_torture_boost_ktrerror = 0;
2005         n_rcu_torture_boost_rterror = 0;
2006         n_rcu_torture_boost_failure = 0;
2007         n_rcu_torture_boosts = 0;
2008         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
2009                 atomic_set(&rcu_torture_wcount[i], 0);
2010         for_each_possible_cpu(cpu) {
2011                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
2012                         per_cpu(rcu_torture_count, cpu)[i] = 0;
2013                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
2014                 }
2015         }
2016 
2017         /* Start up the kthreads. */
2018 
2019         firsterr = torture_create_kthread(rcu_torture_writer, NULL,
2020                                           writer_task);
2021         if (firsterr)
2022                 goto unwind;
2023         if (nfakewriters > 0) {
2024                 fakewriter_tasks = kcalloc(nfakewriters,
2025                                            sizeof(fakewriter_tasks[0]),
2026                                            GFP_KERNEL);
2027                 if (fakewriter_tasks == NULL) {
2028                         VERBOSE_TOROUT_ERRSTRING("out of memory");
2029                         firsterr = -ENOMEM;
2030                         goto unwind;
2031                 }
2032         }
2033         for (i = 0; i < nfakewriters; i++) {
2034                 firsterr = torture_create_kthread(rcu_torture_fakewriter,
2035                                                   NULL, fakewriter_tasks[i]);
2036                 if (firsterr)
2037                         goto unwind;
2038         }
2039         reader_tasks = kcalloc(nrealreaders, sizeof(reader_tasks[0]),
2040                                GFP_KERNEL);
2041         if (reader_tasks == NULL) {
2042                 VERBOSE_TOROUT_ERRSTRING("out of memory");
2043                 firsterr = -ENOMEM;
2044                 goto unwind;
2045         }
2046         for (i = 0; i < nrealreaders; i++) {
2047                 firsterr = torture_create_kthread(rcu_torture_reader, NULL,
2048                                                   reader_tasks[i]);
2049                 if (firsterr)
2050                         goto unwind;
2051         }
2052         if (stat_interval > 0) {
2053                 firsterr = torture_create_kthread(rcu_torture_stats, NULL,
2054                                                   stats_task);
2055                 if (firsterr)
2056                         goto unwind;
2057         }
2058         if (test_no_idle_hz && shuffle_interval > 0) {
2059                 firsterr = torture_shuffle_init(shuffle_interval * HZ);
2060                 if (firsterr)
2061                         goto unwind;
2062         }
2063         if (stutter < 0)
2064                 stutter = 0;
2065         if (stutter) {
2066                 firsterr = torture_stutter_init(stutter * HZ);
2067                 if (firsterr)
2068                         goto unwind;
2069         }
2070         if (fqs_duration < 0)
2071                 fqs_duration = 0;
2072         if (fqs_duration) {
2073                 /* Create the fqs thread */
2074                 firsterr = torture_create_kthread(rcu_torture_fqs, NULL,
2075                                                   fqs_task);
2076                 if (firsterr)
2077                         goto unwind;
2078         }
2079         if (test_boost_interval < 1)
2080                 test_boost_interval = 1;
2081         if (test_boost_duration < 2)
2082                 test_boost_duration = 2;
2083         if (rcu_torture_can_boost()) {
2084 
2085                 boost_starttime = jiffies + test_boost_interval * HZ;
2086 
2087                 firsterr = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "RCU_TORTURE",
2088                                              rcutorture_booster_init,
2089                                              rcutorture_booster_cleanup);
2090                 if (firsterr < 0)
2091                         goto unwind;
2092                 rcutor_hp = firsterr;
2093         }
2094         firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup);
2095         if (firsterr)
2096                 goto unwind;
2097         firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval);
2098         if (firsterr)
2099                 goto unwind;
2100         firsterr = rcu_torture_stall_init();
2101         if (firsterr)
2102                 goto unwind;
2103         firsterr = rcu_torture_barrier_init();
2104         if (firsterr)
2105                 goto unwind;
2106         if (object_debug)
2107                 rcu_test_debug_objects();
2108         if (cbflood_n_burst > 0) {
2109                 /* Create the cbflood threads */
2110                 ncbflooders = (num_online_cpus() + 3) / 4;
2111                 cbflood_task = kcalloc(ncbflooders, sizeof(*cbflood_task),
2112                                        GFP_KERNEL);
2113                 if (!cbflood_task) {
2114                         VERBOSE_TOROUT_ERRSTRING("out of memory");
2115                         firsterr = -ENOMEM;
2116                         goto unwind;
2117                 }
2118                 for (i = 0; i < ncbflooders; i++) {
2119                         firsterr = torture_create_kthread(rcu_torture_cbflood,
2120                                                           NULL,
2121                                                           cbflood_task[i]);
2122                         if (firsterr)
2123                                 goto unwind;
2124                 }
2125         }
2126         torture_init_end();
2127         return 0;
2128 
2129 unwind:
2130         torture_init_end();
2131         rcu_torture_cleanup();
2132         return firsterr;
2133 }
2134 
2135 module_init(rcu_torture_init);
2136 module_exit(rcu_torture_cleanup);
2137 

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