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1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * Read-Copy Update module-based scalability-test facility
4 *
5 * Copyright (C) IBM Corporation, 2015
6 *
7 * Authors: Paul E. McKenney <paulmck@linux.ibm.com>
8 */
9
10#define pr_fmt(fmt) fmt
11
12#include <linux/types.h>
13#include <linux/kernel.h>
14#include <linux/init.h>
15#include <linux/mm.h>
16#include <linux/module.h>
17#include <linux/kthread.h>
18#include <linux/err.h>
19#include <linux/spinlock.h>
20#include <linux/smp.h>
21#include <linux/rcupdate.h>
22#include <linux/interrupt.h>
23#include <linux/sched.h>
24#include <uapi/linux/sched/types.h>
25#include <linux/atomic.h>
26#include <linux/bitops.h>
27#include <linux/completion.h>
28#include <linux/moduleparam.h>
29#include <linux/percpu.h>
30#include <linux/notifier.h>
31#include <linux/reboot.h>
32#include <linux/freezer.h>
33#include <linux/cpu.h>
34#include <linux/delay.h>
35#include <linux/stat.h>
36#include <linux/srcu.h>
37#include <linux/slab.h>
38#include <asm/byteorder.h>
39#include <linux/torture.h>
40#include <linux/vmalloc.h>
41#include <linux/rcupdate_trace.h>
42
43#include "rcu.h"
44
45MODULE_LICENSE("GPL");
46MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com>");
47
48#define SCALE_FLAG "-scale:"
49#define SCALEOUT_STRING(s) \
50 pr_alert("%s" SCALE_FLAG " %s\n", scale_type, s)
51#define VERBOSE_SCALEOUT_STRING(s) \
52 do { if (verbose) pr_alert("%s" SCALE_FLAG " %s\n", scale_type, s); } while (0)
53#define SCALEOUT_ERRSTRING(s) \
54 pr_alert("%s" SCALE_FLAG "!!! %s\n", scale_type, s)
55
56/*
57 * The intended use cases for the nreaders and nwriters module parameters
58 * are as follows:
59 *
60 * 1. Specify only the nr_cpus kernel boot parameter. This will
61 * set both nreaders and nwriters to the value specified by
62 * nr_cpus for a mixed reader/writer test.
63 *
64 * 2. Specify the nr_cpus kernel boot parameter, but set
65 * rcuscale.nreaders to zero. This will set nwriters to the
66 * value specified by nr_cpus for an update-only test.
67 *
68 * 3. Specify the nr_cpus kernel boot parameter, but set
69 * rcuscale.nwriters to zero. This will set nreaders to the
70 * value specified by nr_cpus for a read-only test.
71 *
72 * Various other use cases may of course be specified.
73 *
74 * Note that this test's readers are intended only as a test load for
75 * the writers. The reader scalability statistics will be overly
76 * pessimistic due to the per-critical-section interrupt disabling,
77 * test-end checks, and the pair of calls through pointers.
78 */
79
80#ifdef MODULE
81# define RCUSCALE_SHUTDOWN 0
82#else
83# define RCUSCALE_SHUTDOWN 1
84#endif
85
86torture_param(bool, gp_async, false, "Use asynchronous GP wait primitives");
87torture_param(int, gp_async_max, 1000, "Max # outstanding waits per reader");
88torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
89torture_param(int, holdoff, 10, "Holdoff time before test start (s)");
90torture_param(int, nreaders, -1, "Number of RCU reader threads");
91torture_param(int, nwriters, -1, "Number of RCU updater threads");
92torture_param(bool, shutdown, RCUSCALE_SHUTDOWN,
93 "Shutdown at end of scalability tests.");
94torture_param(int, verbose, 1, "Enable verbose debugging printk()s");
95torture_param(int, writer_holdoff, 0, "Holdoff (us) between GPs, zero to disable");
96torture_param(int, kfree_rcu_test, 0, "Do we run a kfree_rcu() scale test?");
97torture_param(int, kfree_mult, 1, "Multiple of kfree_obj size to allocate.");
98torture_param(int, kfree_by_call_rcu, 0, "Use call_rcu() to emulate kfree_rcu()?");
99
100static char *scale_type = "rcu";
101module_param(scale_type, charp, 0444);
102MODULE_PARM_DESC(scale_type, "Type of RCU to scalability-test (rcu, srcu, ...)");
103
104static int nrealreaders;
105static int nrealwriters;
106static struct task_struct **writer_tasks;
107static struct task_struct **reader_tasks;
108static struct task_struct *shutdown_task;
109
110static u64 **writer_durations;
111static int *writer_n_durations;
112static atomic_t n_rcu_scale_reader_started;
113static atomic_t n_rcu_scale_writer_started;
114static atomic_t n_rcu_scale_writer_finished;
115static wait_queue_head_t shutdown_wq;
116static u64 t_rcu_scale_writer_started;
117static u64 t_rcu_scale_writer_finished;
118static unsigned long b_rcu_gp_test_started;
119static unsigned long b_rcu_gp_test_finished;
120static DEFINE_PER_CPU(atomic_t, n_async_inflight);
121
122#define MAX_MEAS 10000
123#define MIN_MEAS 100
124
125/*
126 * Operations vector for selecting different types of tests.
127 */
128
129struct rcu_scale_ops {
130 int ptype;
131 void (*init)(void);
132 void (*cleanup)(void);
133 int (*readlock)(void);
134 void (*readunlock)(int idx);
135 unsigned long (*get_gp_seq)(void);
136 unsigned long (*gp_diff)(unsigned long new, unsigned long old);
137 unsigned long (*exp_completed)(void);
138 void (*async)(struct rcu_head *head, rcu_callback_t func);
139 void (*gp_barrier)(void);
140 void (*sync)(void);
141 void (*exp_sync)(void);
142 const char *name;
143};
144
145static struct rcu_scale_ops *cur_ops;
146
147/*
148 * Definitions for rcu scalability testing.
149 */
150
151static int rcu_scale_read_lock(void) __acquires(RCU)
152{
153 rcu_read_lock();
154 return 0;
155}
156
157static void rcu_scale_read_unlock(int idx) __releases(RCU)
158{
159 rcu_read_unlock();
160}
161
162static unsigned long __maybe_unused rcu_no_completed(void)
163{
164 return 0;
165}
166
167static void rcu_sync_scale_init(void)
168{
169}
170
171static struct rcu_scale_ops rcu_ops = {
172 .ptype = RCU_FLAVOR,
173 .init = rcu_sync_scale_init,
174 .readlock = rcu_scale_read_lock,
175 .readunlock = rcu_scale_read_unlock,
176 .get_gp_seq = rcu_get_gp_seq,
177 .gp_diff = rcu_seq_diff,
178 .exp_completed = rcu_exp_batches_completed,
179 .async = call_rcu_hurry,
180 .gp_barrier = rcu_barrier,
181 .sync = synchronize_rcu,
182 .exp_sync = synchronize_rcu_expedited,
183 .name = "rcu"
184};
185
186/*
187 * Definitions for srcu scalability testing.
188 */
189
190DEFINE_STATIC_SRCU(srcu_ctl_scale);
191static struct srcu_struct *srcu_ctlp = &srcu_ctl_scale;
192
193static int srcu_scale_read_lock(void) __acquires(srcu_ctlp)
194{
195 return srcu_read_lock(srcu_ctlp);
196}
197
198static void srcu_scale_read_unlock(int idx) __releases(srcu_ctlp)
199{
200 srcu_read_unlock(srcu_ctlp, idx);
201}
202
203static unsigned long srcu_scale_completed(void)
204{
205 return srcu_batches_completed(srcu_ctlp);
206}
207
208static void srcu_call_rcu(struct rcu_head *head, rcu_callback_t func)
209{
210 call_srcu(srcu_ctlp, head, func);
211}
212
213static void srcu_rcu_barrier(void)
214{
215 srcu_barrier(srcu_ctlp);
216}
217
218static void srcu_scale_synchronize(void)
219{
220 synchronize_srcu(srcu_ctlp);
221}
222
223static void srcu_scale_synchronize_expedited(void)
224{
225 synchronize_srcu_expedited(srcu_ctlp);
226}
227
228static struct rcu_scale_ops srcu_ops = {
229 .ptype = SRCU_FLAVOR,
230 .init = rcu_sync_scale_init,
231 .readlock = srcu_scale_read_lock,
232 .readunlock = srcu_scale_read_unlock,
233 .get_gp_seq = srcu_scale_completed,
234 .gp_diff = rcu_seq_diff,
235 .exp_completed = srcu_scale_completed,
236 .async = srcu_call_rcu,
237 .gp_barrier = srcu_rcu_barrier,
238 .sync = srcu_scale_synchronize,
239 .exp_sync = srcu_scale_synchronize_expedited,
240 .name = "srcu"
241};
242
243static struct srcu_struct srcud;
244
245static void srcu_sync_scale_init(void)
246{
247 srcu_ctlp = &srcud;
248 init_srcu_struct(srcu_ctlp);
249}
250
251static void srcu_sync_scale_cleanup(void)
252{
253 cleanup_srcu_struct(srcu_ctlp);
254}
255
256static struct rcu_scale_ops srcud_ops = {
257 .ptype = SRCU_FLAVOR,
258 .init = srcu_sync_scale_init,
259 .cleanup = srcu_sync_scale_cleanup,
260 .readlock = srcu_scale_read_lock,
261 .readunlock = srcu_scale_read_unlock,
262 .get_gp_seq = srcu_scale_completed,
263 .gp_diff = rcu_seq_diff,
264 .exp_completed = srcu_scale_completed,
265 .async = srcu_call_rcu,
266 .gp_barrier = srcu_rcu_barrier,
267 .sync = srcu_scale_synchronize,
268 .exp_sync = srcu_scale_synchronize_expedited,
269 .name = "srcud"
270};
271
272#ifdef CONFIG_TASKS_RCU
273
274/*
275 * Definitions for RCU-tasks scalability testing.
276 */
277
278static int tasks_scale_read_lock(void)
279{
280 return 0;
281}
282
283static void tasks_scale_read_unlock(int idx)
284{
285}
286
287static struct rcu_scale_ops tasks_ops = {
288 .ptype = RCU_TASKS_FLAVOR,
289 .init = rcu_sync_scale_init,
290 .readlock = tasks_scale_read_lock,
291 .readunlock = tasks_scale_read_unlock,
292 .get_gp_seq = rcu_no_completed,
293 .gp_diff = rcu_seq_diff,
294 .async = call_rcu_tasks,
295 .gp_barrier = rcu_barrier_tasks,
296 .sync = synchronize_rcu_tasks,
297 .exp_sync = synchronize_rcu_tasks,
298 .name = "tasks"
299};
300
301#define TASKS_OPS &tasks_ops,
302
303#else // #ifdef CONFIG_TASKS_RCU
304
305#define TASKS_OPS
306
307#endif // #else // #ifdef CONFIG_TASKS_RCU
308
309#ifdef CONFIG_TASKS_TRACE_RCU
310
311/*
312 * Definitions for RCU-tasks-trace scalability testing.
313 */
314
315static int tasks_trace_scale_read_lock(void)
316{
317 rcu_read_lock_trace();
318 return 0;
319}
320
321static void tasks_trace_scale_read_unlock(int idx)
322{
323 rcu_read_unlock_trace();
324}
325
326static struct rcu_scale_ops tasks_tracing_ops = {
327 .ptype = RCU_TASKS_FLAVOR,
328 .init = rcu_sync_scale_init,
329 .readlock = tasks_trace_scale_read_lock,
330 .readunlock = tasks_trace_scale_read_unlock,
331 .get_gp_seq = rcu_no_completed,
332 .gp_diff = rcu_seq_diff,
333 .async = call_rcu_tasks_trace,
334 .gp_barrier = rcu_barrier_tasks_trace,
335 .sync = synchronize_rcu_tasks_trace,
336 .exp_sync = synchronize_rcu_tasks_trace,
337 .name = "tasks-tracing"
338};
339
340#define TASKS_TRACING_OPS &tasks_tracing_ops,
341
342#else // #ifdef CONFIG_TASKS_TRACE_RCU
343
344#define TASKS_TRACING_OPS
345
346#endif // #else // #ifdef CONFIG_TASKS_TRACE_RCU
347
348static unsigned long rcuscale_seq_diff(unsigned long new, unsigned long old)
349{
350 if (!cur_ops->gp_diff)
351 return new - old;
352 return cur_ops->gp_diff(new, old);
353}
354
355/*
356 * If scalability tests complete, wait for shutdown to commence.
357 */
358static void rcu_scale_wait_shutdown(void)
359{
360 cond_resched_tasks_rcu_qs();
361 if (atomic_read(&n_rcu_scale_writer_finished) < nrealwriters)
362 return;
363 while (!torture_must_stop())
364 schedule_timeout_uninterruptible(1);
365}
366
367/*
368 * RCU scalability reader kthread. Repeatedly does empty RCU read-side
369 * critical section, minimizing update-side interference. However, the
370 * point of this test is not to evaluate reader scalability, but instead
371 * to serve as a test load for update-side scalability testing.
372 */
373static int
374rcu_scale_reader(void *arg)
375{
376 unsigned long flags;
377 int idx;
378 long me = (long)arg;
379
380 VERBOSE_SCALEOUT_STRING("rcu_scale_reader task started");
381 set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
382 set_user_nice(current, MAX_NICE);
383 atomic_inc(&n_rcu_scale_reader_started);
384
385 do {
386 local_irq_save(flags);
387 idx = cur_ops->readlock();
388 cur_ops->readunlock(idx);
389 local_irq_restore(flags);
390 rcu_scale_wait_shutdown();
391 } while (!torture_must_stop());
392 torture_kthread_stopping("rcu_scale_reader");
393 return 0;
394}
395
396/*
397 * Callback function for asynchronous grace periods from rcu_scale_writer().
398 */
399static void rcu_scale_async_cb(struct rcu_head *rhp)
400{
401 atomic_dec(this_cpu_ptr(&n_async_inflight));
402 kfree(rhp);
403}
404
405/*
406 * RCU scale writer kthread. Repeatedly does a grace period.
407 */
408static int
409rcu_scale_writer(void *arg)
410{
411 int i = 0;
412 int i_max;
413 long me = (long)arg;
414 struct rcu_head *rhp = NULL;
415 bool started = false, done = false, alldone = false;
416 u64 t;
417 u64 *wdp;
418 u64 *wdpp = writer_durations[me];
419
420 VERBOSE_SCALEOUT_STRING("rcu_scale_writer task started");
421 WARN_ON(!wdpp);
422 set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
423 current->flags |= PF_NO_SETAFFINITY;
424 sched_set_fifo_low(current);
425
426 if (holdoff)
427 schedule_timeout_uninterruptible(holdoff * HZ);
428
429 /*
430 * Wait until rcu_end_inkernel_boot() is called for normal GP tests
431 * so that RCU is not always expedited for normal GP tests.
432 * The system_state test is approximate, but works well in practice.
433 */
434 while (!gp_exp && system_state != SYSTEM_RUNNING)
435 schedule_timeout_uninterruptible(1);
436
437 t = ktime_get_mono_fast_ns();
438 if (atomic_inc_return(&n_rcu_scale_writer_started) >= nrealwriters) {
439 t_rcu_scale_writer_started = t;
440 if (gp_exp) {
441 b_rcu_gp_test_started =
442 cur_ops->exp_completed() / 2;
443 } else {
444 b_rcu_gp_test_started = cur_ops->get_gp_seq();
445 }
446 }
447
448 do {
449 if (writer_holdoff)
450 udelay(writer_holdoff);
451 wdp = &wdpp[i];
452 *wdp = ktime_get_mono_fast_ns();
453 if (gp_async) {
454retry:
455 if (!rhp)
456 rhp = kmalloc(sizeof(*rhp), GFP_KERNEL);
457 if (rhp && atomic_read(this_cpu_ptr(&n_async_inflight)) < gp_async_max) {
458 atomic_inc(this_cpu_ptr(&n_async_inflight));
459 cur_ops->async(rhp, rcu_scale_async_cb);
460 rhp = NULL;
461 } else if (!kthread_should_stop()) {
462 cur_ops->gp_barrier();
463 goto retry;
464 } else {
465 kfree(rhp); /* Because we are stopping. */
466 }
467 } else if (gp_exp) {
468 cur_ops->exp_sync();
469 } else {
470 cur_ops->sync();
471 }
472 t = ktime_get_mono_fast_ns();
473 *wdp = t - *wdp;
474 i_max = i;
475 if (!started &&
476 atomic_read(&n_rcu_scale_writer_started) >= nrealwriters)
477 started = true;
478 if (!done && i >= MIN_MEAS) {
479 done = true;
480 sched_set_normal(current, 0);
481 pr_alert("%s%s rcu_scale_writer %ld has %d measurements\n",
482 scale_type, SCALE_FLAG, me, MIN_MEAS);
483 if (atomic_inc_return(&n_rcu_scale_writer_finished) >=
484 nrealwriters) {
485 schedule_timeout_interruptible(10);
486 rcu_ftrace_dump(DUMP_ALL);
487 SCALEOUT_STRING("Test complete");
488 t_rcu_scale_writer_finished = t;
489 if (gp_exp) {
490 b_rcu_gp_test_finished =
491 cur_ops->exp_completed() / 2;
492 } else {
493 b_rcu_gp_test_finished =
494 cur_ops->get_gp_seq();
495 }
496 if (shutdown) {
497 smp_mb(); /* Assign before wake. */
498 wake_up(&shutdown_wq);
499 }
500 }
501 }
502 if (done && !alldone &&
503 atomic_read(&n_rcu_scale_writer_finished) >= nrealwriters)
504 alldone = true;
505 if (started && !alldone && i < MAX_MEAS - 1)
506 i++;
507 rcu_scale_wait_shutdown();
508 } while (!torture_must_stop());
509 if (gp_async) {
510 cur_ops->gp_barrier();
511 }
512 writer_n_durations[me] = i_max + 1;
513 torture_kthread_stopping("rcu_scale_writer");
514 return 0;
515}
516
517static void
518rcu_scale_print_module_parms(struct rcu_scale_ops *cur_ops, const char *tag)
519{
520 pr_alert("%s" SCALE_FLAG
521 "--- %s: nreaders=%d nwriters=%d verbose=%d shutdown=%d\n",
522 scale_type, tag, nrealreaders, nrealwriters, verbose, shutdown);
523}
524
525static void
526rcu_scale_cleanup(void)
527{
528 int i;
529 int j;
530 int ngps = 0;
531 u64 *wdp;
532 u64 *wdpp;
533
534 /*
535 * Would like warning at start, but everything is expedited
536 * during the mid-boot phase, so have to wait till the end.
537 */
538 if (rcu_gp_is_expedited() && !rcu_gp_is_normal() && !gp_exp)
539 SCALEOUT_ERRSTRING("All grace periods expedited, no normal ones to measure!");
540 if (rcu_gp_is_normal() && gp_exp)
541 SCALEOUT_ERRSTRING("All grace periods normal, no expedited ones to measure!");
542 if (gp_exp && gp_async)
543 SCALEOUT_ERRSTRING("No expedited async GPs, so went with async!");
544
545 if (torture_cleanup_begin())
546 return;
547 if (!cur_ops) {
548 torture_cleanup_end();
549 return;
550 }
551
552 if (reader_tasks) {
553 for (i = 0; i < nrealreaders; i++)
554 torture_stop_kthread(rcu_scale_reader,
555 reader_tasks[i]);
556 kfree(reader_tasks);
557 }
558
559 if (writer_tasks) {
560 for (i = 0; i < nrealwriters; i++) {
561 torture_stop_kthread(rcu_scale_writer,
562 writer_tasks[i]);
563 if (!writer_n_durations)
564 continue;
565 j = writer_n_durations[i];
566 pr_alert("%s%s writer %d gps: %d\n",
567 scale_type, SCALE_FLAG, i, j);
568 ngps += j;
569 }
570 pr_alert("%s%s start: %llu end: %llu duration: %llu gps: %d batches: %ld\n",
571 scale_type, SCALE_FLAG,
572 t_rcu_scale_writer_started, t_rcu_scale_writer_finished,
573 t_rcu_scale_writer_finished -
574 t_rcu_scale_writer_started,
575 ngps,
576 rcuscale_seq_diff(b_rcu_gp_test_finished,
577 b_rcu_gp_test_started));
578 for (i = 0; i < nrealwriters; i++) {
579 if (!writer_durations)
580 break;
581 if (!writer_n_durations)
582 continue;
583 wdpp = writer_durations[i];
584 if (!wdpp)
585 continue;
586 for (j = 0; j < writer_n_durations[i]; j++) {
587 wdp = &wdpp[j];
588 pr_alert("%s%s %4d writer-duration: %5d %llu\n",
589 scale_type, SCALE_FLAG,
590 i, j, *wdp);
591 if (j % 100 == 0)
592 schedule_timeout_uninterruptible(1);
593 }
594 kfree(writer_durations[i]);
595 }
596 kfree(writer_tasks);
597 kfree(writer_durations);
598 kfree(writer_n_durations);
599 }
600
601 /* Do torture-type-specific cleanup operations. */
602 if (cur_ops->cleanup != NULL)
603 cur_ops->cleanup();
604
605 torture_cleanup_end();
606}
607
608/*
609 * Return the number if non-negative. If -1, the number of CPUs.
610 * If less than -1, that much less than the number of CPUs, but
611 * at least one.
612 */
613static int compute_real(int n)
614{
615 int nr;
616
617 if (n >= 0) {
618 nr = n;
619 } else {
620 nr = num_online_cpus() + 1 + n;
621 if (nr <= 0)
622 nr = 1;
623 }
624 return nr;
625}
626
627/*
628 * RCU scalability shutdown kthread. Just waits to be awakened, then shuts
629 * down system.
630 */
631static int
632rcu_scale_shutdown(void *arg)
633{
634 wait_event(shutdown_wq,
635 atomic_read(&n_rcu_scale_writer_finished) >= nrealwriters);
636 smp_mb(); /* Wake before output. */
637 rcu_scale_cleanup();
638 kernel_power_off();
639 return -EINVAL;
640}
641
642/*
643 * kfree_rcu() scalability tests: Start a kfree_rcu() loop on all CPUs for number
644 * of iterations and measure total time and number of GP for all iterations to complete.
645 */
646
647torture_param(int, kfree_nthreads, -1, "Number of threads running loops of kfree_rcu().");
648torture_param(int, kfree_alloc_num, 8000, "Number of allocations and frees done in an iteration.");
649torture_param(int, kfree_loops, 10, "Number of loops doing kfree_alloc_num allocations and frees.");
650torture_param(bool, kfree_rcu_test_double, false, "Do we run a kfree_rcu() double-argument scale test?");
651torture_param(bool, kfree_rcu_test_single, false, "Do we run a kfree_rcu() single-argument scale test?");
652
653static struct task_struct **kfree_reader_tasks;
654static int kfree_nrealthreads;
655static atomic_t n_kfree_scale_thread_started;
656static atomic_t n_kfree_scale_thread_ended;
657
658struct kfree_obj {
659 char kfree_obj[8];
660 struct rcu_head rh;
661};
662
663/* Used if doing RCU-kfree'ing via call_rcu(). */
664static void kfree_call_rcu(struct rcu_head *rh)
665{
666 struct kfree_obj *obj = container_of(rh, struct kfree_obj, rh);
667
668 kfree(obj);
669}
670
671static int
672kfree_scale_thread(void *arg)
673{
674 int i, loop = 0;
675 long me = (long)arg;
676 struct kfree_obj *alloc_ptr;
677 u64 start_time, end_time;
678 long long mem_begin, mem_during = 0;
679 bool kfree_rcu_test_both;
680 DEFINE_TORTURE_RANDOM(tr);
681
682 VERBOSE_SCALEOUT_STRING("kfree_scale_thread task started");
683 set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
684 set_user_nice(current, MAX_NICE);
685 kfree_rcu_test_both = (kfree_rcu_test_single == kfree_rcu_test_double);
686
687 start_time = ktime_get_mono_fast_ns();
688
689 if (atomic_inc_return(&n_kfree_scale_thread_started) >= kfree_nrealthreads) {
690 if (gp_exp)
691 b_rcu_gp_test_started = cur_ops->exp_completed() / 2;
692 else
693 b_rcu_gp_test_started = cur_ops->get_gp_seq();
694 }
695
696 do {
697 if (!mem_during) {
698 mem_during = mem_begin = si_mem_available();
699 } else if (loop % (kfree_loops / 4) == 0) {
700 mem_during = (mem_during + si_mem_available()) / 2;
701 }
702
703 for (i = 0; i < kfree_alloc_num; i++) {
704 alloc_ptr = kmalloc(kfree_mult * sizeof(struct kfree_obj), GFP_KERNEL);
705 if (!alloc_ptr)
706 return -ENOMEM;
707
708 if (kfree_by_call_rcu) {
709 call_rcu(&(alloc_ptr->rh), kfree_call_rcu);
710 continue;
711 }
712
713 // By default kfree_rcu_test_single and kfree_rcu_test_double are
714 // initialized to false. If both have the same value (false or true)
715 // both are randomly tested, otherwise only the one with value true
716 // is tested.
717 if ((kfree_rcu_test_single && !kfree_rcu_test_double) ||
718 (kfree_rcu_test_both && torture_random(&tr) & 0x800))
719 kfree_rcu(alloc_ptr);
720 else
721 kfree_rcu(alloc_ptr, rh);
722 }
723
724 cond_resched();
725 } while (!torture_must_stop() && ++loop < kfree_loops);
726
727 if (atomic_inc_return(&n_kfree_scale_thread_ended) >= kfree_nrealthreads) {
728 end_time = ktime_get_mono_fast_ns();
729
730 if (gp_exp)
731 b_rcu_gp_test_finished = cur_ops->exp_completed() / 2;
732 else
733 b_rcu_gp_test_finished = cur_ops->get_gp_seq();
734
735 pr_alert("Total time taken by all kfree'ers: %llu ns, loops: %d, batches: %ld, memory footprint: %lldMB\n",
736 (unsigned long long)(end_time - start_time), kfree_loops,
737 rcuscale_seq_diff(b_rcu_gp_test_finished, b_rcu_gp_test_started),
738 (mem_begin - mem_during) >> (20 - PAGE_SHIFT));
739
740 if (shutdown) {
741 smp_mb(); /* Assign before wake. */
742 wake_up(&shutdown_wq);
743 }
744 }
745
746 torture_kthread_stopping("kfree_scale_thread");
747 return 0;
748}
749
750static void
751kfree_scale_cleanup(void)
752{
753 int i;
754
755 if (torture_cleanup_begin())
756 return;
757
758 if (kfree_reader_tasks) {
759 for (i = 0; i < kfree_nrealthreads; i++)
760 torture_stop_kthread(kfree_scale_thread,
761 kfree_reader_tasks[i]);
762 kfree(kfree_reader_tasks);
763 }
764
765 torture_cleanup_end();
766}
767
768/*
769 * shutdown kthread. Just waits to be awakened, then shuts down system.
770 */
771static int
772kfree_scale_shutdown(void *arg)
773{
774 wait_event(shutdown_wq,
775 atomic_read(&n_kfree_scale_thread_ended) >= kfree_nrealthreads);
776
777 smp_mb(); /* Wake before output. */
778
779 kfree_scale_cleanup();
780 kernel_power_off();
781 return -EINVAL;
782}
783
784// Used if doing RCU-kfree'ing via call_rcu().
785static unsigned long jiffies_at_lazy_cb;
786static struct rcu_head lazy_test1_rh;
787static int rcu_lazy_test1_cb_called;
788static void call_rcu_lazy_test1(struct rcu_head *rh)
789{
790 jiffies_at_lazy_cb = jiffies;
791 WRITE_ONCE(rcu_lazy_test1_cb_called, 1);
792}
793
794static int __init
795kfree_scale_init(void)
796{
797 int firsterr = 0;
798 long i;
799 unsigned long jif_start;
800 unsigned long orig_jif;
801
802 // Also, do a quick self-test to ensure laziness is as much as
803 // expected.
804 if (kfree_by_call_rcu && !IS_ENABLED(CONFIG_RCU_LAZY)) {
805 pr_alert("CONFIG_RCU_LAZY is disabled, falling back to kfree_rcu() for delayed RCU kfree'ing\n");
806 kfree_by_call_rcu = 0;
807 }
808
809 if (kfree_by_call_rcu) {
810 /* do a test to check the timeout. */
811 orig_jif = rcu_lazy_get_jiffies_till_flush();
812
813 rcu_lazy_set_jiffies_till_flush(2 * HZ);
814 rcu_barrier();
815
816 jif_start = jiffies;
817 jiffies_at_lazy_cb = 0;
818 call_rcu(&lazy_test1_rh, call_rcu_lazy_test1);
819
820 smp_cond_load_relaxed(&rcu_lazy_test1_cb_called, VAL == 1);
821
822 rcu_lazy_set_jiffies_till_flush(orig_jif);
823
824 if (WARN_ON_ONCE(jiffies_at_lazy_cb - jif_start < 2 * HZ)) {
825 pr_alert("ERROR: call_rcu() CBs are not being lazy as expected!\n");
826 WARN_ON_ONCE(1);
827 return -1;
828 }
829
830 if (WARN_ON_ONCE(jiffies_at_lazy_cb - jif_start > 3 * HZ)) {
831 pr_alert("ERROR: call_rcu() CBs are being too lazy!\n");
832 WARN_ON_ONCE(1);
833 return -1;
834 }
835 }
836
837 kfree_nrealthreads = compute_real(kfree_nthreads);
838 /* Start up the kthreads. */
839 if (shutdown) {
840 init_waitqueue_head(&shutdown_wq);
841 firsterr = torture_create_kthread(kfree_scale_shutdown, NULL,
842 shutdown_task);
843 if (torture_init_error(firsterr))
844 goto unwind;
845 schedule_timeout_uninterruptible(1);
846 }
847
848 pr_alert("kfree object size=%zu, kfree_by_call_rcu=%d\n",
849 kfree_mult * sizeof(struct kfree_obj),
850 kfree_by_call_rcu);
851
852 kfree_reader_tasks = kcalloc(kfree_nrealthreads, sizeof(kfree_reader_tasks[0]),
853 GFP_KERNEL);
854 if (kfree_reader_tasks == NULL) {
855 firsterr = -ENOMEM;
856 goto unwind;
857 }
858
859 for (i = 0; i < kfree_nrealthreads; i++) {
860 firsterr = torture_create_kthread(kfree_scale_thread, (void *)i,
861 kfree_reader_tasks[i]);
862 if (torture_init_error(firsterr))
863 goto unwind;
864 }
865
866 while (atomic_read(&n_kfree_scale_thread_started) < kfree_nrealthreads)
867 schedule_timeout_uninterruptible(1);
868
869 torture_init_end();
870 return 0;
871
872unwind:
873 torture_init_end();
874 kfree_scale_cleanup();
875 return firsterr;
876}
877
878static int __init
879rcu_scale_init(void)
880{
881 long i;
882 int firsterr = 0;
883 static struct rcu_scale_ops *scale_ops[] = {
884 &rcu_ops, &srcu_ops, &srcud_ops, TASKS_OPS TASKS_TRACING_OPS
885 };
886
887 if (!torture_init_begin(scale_type, verbose))
888 return -EBUSY;
889
890 /* Process args and announce that the scalability'er is on the job. */
891 for (i = 0; i < ARRAY_SIZE(scale_ops); i++) {
892 cur_ops = scale_ops[i];
893 if (strcmp(scale_type, cur_ops->name) == 0)
894 break;
895 }
896 if (i == ARRAY_SIZE(scale_ops)) {
897 pr_alert("rcu-scale: invalid scale type: \"%s\"\n", scale_type);
898 pr_alert("rcu-scale types:");
899 for (i = 0; i < ARRAY_SIZE(scale_ops); i++)
900 pr_cont(" %s", scale_ops[i]->name);
901 pr_cont("\n");
902 firsterr = -EINVAL;
903 cur_ops = NULL;
904 goto unwind;
905 }
906 if (cur_ops->init)
907 cur_ops->init();
908
909 if (kfree_rcu_test)
910 return kfree_scale_init();
911
912 nrealwriters = compute_real(nwriters);
913 nrealreaders = compute_real(nreaders);
914 atomic_set(&n_rcu_scale_reader_started, 0);
915 atomic_set(&n_rcu_scale_writer_started, 0);
916 atomic_set(&n_rcu_scale_writer_finished, 0);
917 rcu_scale_print_module_parms(cur_ops, "Start of test");
918
919 /* Start up the kthreads. */
920
921 if (shutdown) {
922 init_waitqueue_head(&shutdown_wq);
923 firsterr = torture_create_kthread(rcu_scale_shutdown, NULL,
924 shutdown_task);
925 if (torture_init_error(firsterr))
926 goto unwind;
927 schedule_timeout_uninterruptible(1);
928 }
929 reader_tasks = kcalloc(nrealreaders, sizeof(reader_tasks[0]),
930 GFP_KERNEL);
931 if (reader_tasks == NULL) {
932 SCALEOUT_ERRSTRING("out of memory");
933 firsterr = -ENOMEM;
934 goto unwind;
935 }
936 for (i = 0; i < nrealreaders; i++) {
937 firsterr = torture_create_kthread(rcu_scale_reader, (void *)i,
938 reader_tasks[i]);
939 if (torture_init_error(firsterr))
940 goto unwind;
941 }
942 while (atomic_read(&n_rcu_scale_reader_started) < nrealreaders)
943 schedule_timeout_uninterruptible(1);
944 writer_tasks = kcalloc(nrealwriters, sizeof(reader_tasks[0]),
945 GFP_KERNEL);
946 writer_durations = kcalloc(nrealwriters, sizeof(*writer_durations),
947 GFP_KERNEL);
948 writer_n_durations =
949 kcalloc(nrealwriters, sizeof(*writer_n_durations),
950 GFP_KERNEL);
951 if (!writer_tasks || !writer_durations || !writer_n_durations) {
952 SCALEOUT_ERRSTRING("out of memory");
953 firsterr = -ENOMEM;
954 goto unwind;
955 }
956 for (i = 0; i < nrealwriters; i++) {
957 writer_durations[i] =
958 kcalloc(MAX_MEAS, sizeof(*writer_durations[i]),
959 GFP_KERNEL);
960 if (!writer_durations[i]) {
961 firsterr = -ENOMEM;
962 goto unwind;
963 }
964 firsterr = torture_create_kthread(rcu_scale_writer, (void *)i,
965 writer_tasks[i]);
966 if (torture_init_error(firsterr))
967 goto unwind;
968 }
969 torture_init_end();
970 return 0;
971
972unwind:
973 torture_init_end();
974 rcu_scale_cleanup();
975 if (shutdown) {
976 WARN_ON(!IS_MODULE(CONFIG_RCU_SCALE_TEST));
977 kernel_power_off();
978 }
979 return firsterr;
980}
981
982module_init(rcu_scale_init);
983module_exit(rcu_scale_cleanup);
1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * Read-Copy Update module-based scalability-test facility
4 *
5 * Copyright (C) IBM Corporation, 2015
6 *
7 * Authors: Paul E. McKenney <paulmck@linux.ibm.com>
8 */
9
10#define pr_fmt(fmt) fmt
11
12#include <linux/types.h>
13#include <linux/kernel.h>
14#include <linux/init.h>
15#include <linux/mm.h>
16#include <linux/module.h>
17#include <linux/kthread.h>
18#include <linux/err.h>
19#include <linux/spinlock.h>
20#include <linux/smp.h>
21#include <linux/rcupdate.h>
22#include <linux/interrupt.h>
23#include <linux/sched.h>
24#include <uapi/linux/sched/types.h>
25#include <linux/atomic.h>
26#include <linux/bitops.h>
27#include <linux/completion.h>
28#include <linux/moduleparam.h>
29#include <linux/percpu.h>
30#include <linux/notifier.h>
31#include <linux/reboot.h>
32#include <linux/freezer.h>
33#include <linux/cpu.h>
34#include <linux/delay.h>
35#include <linux/stat.h>
36#include <linux/srcu.h>
37#include <linux/slab.h>
38#include <asm/byteorder.h>
39#include <linux/torture.h>
40#include <linux/vmalloc.h>
41#include <linux/rcupdate_trace.h>
42
43#include "rcu.h"
44
45MODULE_LICENSE("GPL");
46MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com>");
47
48#define SCALE_FLAG "-scale:"
49#define SCALEOUT_STRING(s) \
50 pr_alert("%s" SCALE_FLAG " %s\n", scale_type, s)
51#define VERBOSE_SCALEOUT_STRING(s) \
52 do { if (verbose) pr_alert("%s" SCALE_FLAG " %s\n", scale_type, s); } while (0)
53#define SCALEOUT_ERRSTRING(s) \
54 pr_alert("%s" SCALE_FLAG "!!! %s\n", scale_type, s)
55
56/*
57 * The intended use cases for the nreaders and nwriters module parameters
58 * are as follows:
59 *
60 * 1. Specify only the nr_cpus kernel boot parameter. This will
61 * set both nreaders and nwriters to the value specified by
62 * nr_cpus for a mixed reader/writer test.
63 *
64 * 2. Specify the nr_cpus kernel boot parameter, but set
65 * rcuscale.nreaders to zero. This will set nwriters to the
66 * value specified by nr_cpus for an update-only test.
67 *
68 * 3. Specify the nr_cpus kernel boot parameter, but set
69 * rcuscale.nwriters to zero. This will set nreaders to the
70 * value specified by nr_cpus for a read-only test.
71 *
72 * Various other use cases may of course be specified.
73 *
74 * Note that this test's readers are intended only as a test load for
75 * the writers. The reader scalability statistics will be overly
76 * pessimistic due to the per-critical-section interrupt disabling,
77 * test-end checks, and the pair of calls through pointers.
78 */
79
80#ifdef MODULE
81# define RCUSCALE_SHUTDOWN 0
82#else
83# define RCUSCALE_SHUTDOWN 1
84#endif
85
86torture_param(bool, gp_async, false, "Use asynchronous GP wait primitives");
87torture_param(int, gp_async_max, 1000, "Max # outstanding waits per writer");
88torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
89torture_param(int, holdoff, 10, "Holdoff time before test start (s)");
90torture_param(int, minruntime, 0, "Minimum run time (s)");
91torture_param(int, nreaders, -1, "Number of RCU reader threads");
92torture_param(int, nwriters, -1, "Number of RCU updater threads");
93torture_param(bool, shutdown, RCUSCALE_SHUTDOWN,
94 "Shutdown at end of scalability tests.");
95torture_param(int, verbose, 1, "Enable verbose debugging printk()s");
96torture_param(int, writer_holdoff, 0, "Holdoff (us) between GPs, zero to disable");
97torture_param(int, writer_holdoff_jiffies, 0, "Holdoff (jiffies) between GPs, zero to disable");
98torture_param(int, kfree_rcu_test, 0, "Do we run a kfree_rcu() scale test?");
99torture_param(int, kfree_mult, 1, "Multiple of kfree_obj size to allocate.");
100torture_param(int, kfree_by_call_rcu, 0, "Use call_rcu() to emulate kfree_rcu()?");
101
102static char *scale_type = "rcu";
103module_param(scale_type, charp, 0444);
104MODULE_PARM_DESC(scale_type, "Type of RCU to scalability-test (rcu, srcu, ...)");
105
106static int nrealreaders;
107static int nrealwriters;
108static struct task_struct **writer_tasks;
109static struct task_struct **reader_tasks;
110static struct task_struct *shutdown_task;
111
112static u64 **writer_durations;
113static int *writer_n_durations;
114static atomic_t n_rcu_scale_reader_started;
115static atomic_t n_rcu_scale_writer_started;
116static atomic_t n_rcu_scale_writer_finished;
117static wait_queue_head_t shutdown_wq;
118static u64 t_rcu_scale_writer_started;
119static u64 t_rcu_scale_writer_finished;
120static unsigned long b_rcu_gp_test_started;
121static unsigned long b_rcu_gp_test_finished;
122static DEFINE_PER_CPU(atomic_t, n_async_inflight);
123
124#define MAX_MEAS 10000
125#define MIN_MEAS 100
126
127/*
128 * Operations vector for selecting different types of tests.
129 */
130
131struct rcu_scale_ops {
132 int ptype;
133 void (*init)(void);
134 void (*cleanup)(void);
135 int (*readlock)(void);
136 void (*readunlock)(int idx);
137 unsigned long (*get_gp_seq)(void);
138 unsigned long (*gp_diff)(unsigned long new, unsigned long old);
139 unsigned long (*exp_completed)(void);
140 void (*async)(struct rcu_head *head, rcu_callback_t func);
141 void (*gp_barrier)(void);
142 void (*sync)(void);
143 void (*exp_sync)(void);
144 struct task_struct *(*rso_gp_kthread)(void);
145 const char *name;
146};
147
148static struct rcu_scale_ops *cur_ops;
149
150/*
151 * Definitions for rcu scalability testing.
152 */
153
154static int rcu_scale_read_lock(void) __acquires(RCU)
155{
156 rcu_read_lock();
157 return 0;
158}
159
160static void rcu_scale_read_unlock(int idx) __releases(RCU)
161{
162 rcu_read_unlock();
163}
164
165static unsigned long __maybe_unused rcu_no_completed(void)
166{
167 return 0;
168}
169
170static void rcu_sync_scale_init(void)
171{
172}
173
174static struct rcu_scale_ops rcu_ops = {
175 .ptype = RCU_FLAVOR,
176 .init = rcu_sync_scale_init,
177 .readlock = rcu_scale_read_lock,
178 .readunlock = rcu_scale_read_unlock,
179 .get_gp_seq = rcu_get_gp_seq,
180 .gp_diff = rcu_seq_diff,
181 .exp_completed = rcu_exp_batches_completed,
182 .async = call_rcu_hurry,
183 .gp_barrier = rcu_barrier,
184 .sync = synchronize_rcu,
185 .exp_sync = synchronize_rcu_expedited,
186 .name = "rcu"
187};
188
189/*
190 * Definitions for srcu scalability testing.
191 */
192
193DEFINE_STATIC_SRCU(srcu_ctl_scale);
194static struct srcu_struct *srcu_ctlp = &srcu_ctl_scale;
195
196static int srcu_scale_read_lock(void) __acquires(srcu_ctlp)
197{
198 return srcu_read_lock(srcu_ctlp);
199}
200
201static void srcu_scale_read_unlock(int idx) __releases(srcu_ctlp)
202{
203 srcu_read_unlock(srcu_ctlp, idx);
204}
205
206static unsigned long srcu_scale_completed(void)
207{
208 return srcu_batches_completed(srcu_ctlp);
209}
210
211static void srcu_call_rcu(struct rcu_head *head, rcu_callback_t func)
212{
213 call_srcu(srcu_ctlp, head, func);
214}
215
216static void srcu_rcu_barrier(void)
217{
218 srcu_barrier(srcu_ctlp);
219}
220
221static void srcu_scale_synchronize(void)
222{
223 synchronize_srcu(srcu_ctlp);
224}
225
226static void srcu_scale_synchronize_expedited(void)
227{
228 synchronize_srcu_expedited(srcu_ctlp);
229}
230
231static struct rcu_scale_ops srcu_ops = {
232 .ptype = SRCU_FLAVOR,
233 .init = rcu_sync_scale_init,
234 .readlock = srcu_scale_read_lock,
235 .readunlock = srcu_scale_read_unlock,
236 .get_gp_seq = srcu_scale_completed,
237 .gp_diff = rcu_seq_diff,
238 .exp_completed = srcu_scale_completed,
239 .async = srcu_call_rcu,
240 .gp_barrier = srcu_rcu_barrier,
241 .sync = srcu_scale_synchronize,
242 .exp_sync = srcu_scale_synchronize_expedited,
243 .name = "srcu"
244};
245
246static struct srcu_struct srcud;
247
248static void srcu_sync_scale_init(void)
249{
250 srcu_ctlp = &srcud;
251 init_srcu_struct(srcu_ctlp);
252}
253
254static void srcu_sync_scale_cleanup(void)
255{
256 cleanup_srcu_struct(srcu_ctlp);
257}
258
259static struct rcu_scale_ops srcud_ops = {
260 .ptype = SRCU_FLAVOR,
261 .init = srcu_sync_scale_init,
262 .cleanup = srcu_sync_scale_cleanup,
263 .readlock = srcu_scale_read_lock,
264 .readunlock = srcu_scale_read_unlock,
265 .get_gp_seq = srcu_scale_completed,
266 .gp_diff = rcu_seq_diff,
267 .exp_completed = srcu_scale_completed,
268 .async = srcu_call_rcu,
269 .gp_barrier = srcu_rcu_barrier,
270 .sync = srcu_scale_synchronize,
271 .exp_sync = srcu_scale_synchronize_expedited,
272 .name = "srcud"
273};
274
275#ifdef CONFIG_TASKS_RCU
276
277/*
278 * Definitions for RCU-tasks scalability testing.
279 */
280
281static int tasks_scale_read_lock(void)
282{
283 return 0;
284}
285
286static void tasks_scale_read_unlock(int idx)
287{
288}
289
290static struct rcu_scale_ops tasks_ops = {
291 .ptype = RCU_TASKS_FLAVOR,
292 .init = rcu_sync_scale_init,
293 .readlock = tasks_scale_read_lock,
294 .readunlock = tasks_scale_read_unlock,
295 .get_gp_seq = rcu_no_completed,
296 .gp_diff = rcu_seq_diff,
297 .async = call_rcu_tasks,
298 .gp_barrier = rcu_barrier_tasks,
299 .sync = synchronize_rcu_tasks,
300 .exp_sync = synchronize_rcu_tasks,
301 .rso_gp_kthread = get_rcu_tasks_gp_kthread,
302 .name = "tasks"
303};
304
305#define TASKS_OPS &tasks_ops,
306
307#else // #ifdef CONFIG_TASKS_RCU
308
309#define TASKS_OPS
310
311#endif // #else // #ifdef CONFIG_TASKS_RCU
312
313#ifdef CONFIG_TASKS_RUDE_RCU
314
315/*
316 * Definitions for RCU-tasks-rude scalability testing.
317 */
318
319static int tasks_rude_scale_read_lock(void)
320{
321 return 0;
322}
323
324static void tasks_rude_scale_read_unlock(int idx)
325{
326}
327
328static struct rcu_scale_ops tasks_rude_ops = {
329 .ptype = RCU_TASKS_RUDE_FLAVOR,
330 .init = rcu_sync_scale_init,
331 .readlock = tasks_rude_scale_read_lock,
332 .readunlock = tasks_rude_scale_read_unlock,
333 .get_gp_seq = rcu_no_completed,
334 .gp_diff = rcu_seq_diff,
335 .async = call_rcu_tasks_rude,
336 .gp_barrier = rcu_barrier_tasks_rude,
337 .sync = synchronize_rcu_tasks_rude,
338 .exp_sync = synchronize_rcu_tasks_rude,
339 .rso_gp_kthread = get_rcu_tasks_rude_gp_kthread,
340 .name = "tasks-rude"
341};
342
343#define TASKS_RUDE_OPS &tasks_rude_ops,
344
345#else // #ifdef CONFIG_TASKS_RUDE_RCU
346
347#define TASKS_RUDE_OPS
348
349#endif // #else // #ifdef CONFIG_TASKS_RUDE_RCU
350
351#ifdef CONFIG_TASKS_TRACE_RCU
352
353/*
354 * Definitions for RCU-tasks-trace scalability testing.
355 */
356
357static int tasks_trace_scale_read_lock(void)
358{
359 rcu_read_lock_trace();
360 return 0;
361}
362
363static void tasks_trace_scale_read_unlock(int idx)
364{
365 rcu_read_unlock_trace();
366}
367
368static struct rcu_scale_ops tasks_tracing_ops = {
369 .ptype = RCU_TASKS_FLAVOR,
370 .init = rcu_sync_scale_init,
371 .readlock = tasks_trace_scale_read_lock,
372 .readunlock = tasks_trace_scale_read_unlock,
373 .get_gp_seq = rcu_no_completed,
374 .gp_diff = rcu_seq_diff,
375 .async = call_rcu_tasks_trace,
376 .gp_barrier = rcu_barrier_tasks_trace,
377 .sync = synchronize_rcu_tasks_trace,
378 .exp_sync = synchronize_rcu_tasks_trace,
379 .rso_gp_kthread = get_rcu_tasks_trace_gp_kthread,
380 .name = "tasks-tracing"
381};
382
383#define TASKS_TRACING_OPS &tasks_tracing_ops,
384
385#else // #ifdef CONFIG_TASKS_TRACE_RCU
386
387#define TASKS_TRACING_OPS
388
389#endif // #else // #ifdef CONFIG_TASKS_TRACE_RCU
390
391static unsigned long rcuscale_seq_diff(unsigned long new, unsigned long old)
392{
393 if (!cur_ops->gp_diff)
394 return new - old;
395 return cur_ops->gp_diff(new, old);
396}
397
398/*
399 * If scalability tests complete, wait for shutdown to commence.
400 */
401static void rcu_scale_wait_shutdown(void)
402{
403 cond_resched_tasks_rcu_qs();
404 if (atomic_read(&n_rcu_scale_writer_finished) < nrealwriters)
405 return;
406 while (!torture_must_stop())
407 schedule_timeout_uninterruptible(1);
408}
409
410/*
411 * RCU scalability reader kthread. Repeatedly does empty RCU read-side
412 * critical section, minimizing update-side interference. However, the
413 * point of this test is not to evaluate reader scalability, but instead
414 * to serve as a test load for update-side scalability testing.
415 */
416static int
417rcu_scale_reader(void *arg)
418{
419 unsigned long flags;
420 int idx;
421 long me = (long)arg;
422
423 VERBOSE_SCALEOUT_STRING("rcu_scale_reader task started");
424 set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
425 set_user_nice(current, MAX_NICE);
426 atomic_inc(&n_rcu_scale_reader_started);
427
428 do {
429 local_irq_save(flags);
430 idx = cur_ops->readlock();
431 cur_ops->readunlock(idx);
432 local_irq_restore(flags);
433 rcu_scale_wait_shutdown();
434 } while (!torture_must_stop());
435 torture_kthread_stopping("rcu_scale_reader");
436 return 0;
437}
438
439/*
440 * Callback function for asynchronous grace periods from rcu_scale_writer().
441 */
442static void rcu_scale_async_cb(struct rcu_head *rhp)
443{
444 atomic_dec(this_cpu_ptr(&n_async_inflight));
445 kfree(rhp);
446}
447
448/*
449 * RCU scale writer kthread. Repeatedly does a grace period.
450 */
451static int
452rcu_scale_writer(void *arg)
453{
454 int i = 0;
455 int i_max;
456 unsigned long jdone;
457 long me = (long)arg;
458 struct rcu_head *rhp = NULL;
459 bool started = false, done = false, alldone = false;
460 u64 t;
461 DEFINE_TORTURE_RANDOM(tr);
462 u64 *wdp;
463 u64 *wdpp = writer_durations[me];
464
465 VERBOSE_SCALEOUT_STRING("rcu_scale_writer task started");
466 WARN_ON(!wdpp);
467 set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
468 current->flags |= PF_NO_SETAFFINITY;
469 sched_set_fifo_low(current);
470
471 if (holdoff)
472 schedule_timeout_idle(holdoff * HZ);
473
474 /*
475 * Wait until rcu_end_inkernel_boot() is called for normal GP tests
476 * so that RCU is not always expedited for normal GP tests.
477 * The system_state test is approximate, but works well in practice.
478 */
479 while (!gp_exp && system_state != SYSTEM_RUNNING)
480 schedule_timeout_uninterruptible(1);
481
482 t = ktime_get_mono_fast_ns();
483 if (atomic_inc_return(&n_rcu_scale_writer_started) >= nrealwriters) {
484 t_rcu_scale_writer_started = t;
485 if (gp_exp) {
486 b_rcu_gp_test_started =
487 cur_ops->exp_completed() / 2;
488 } else {
489 b_rcu_gp_test_started = cur_ops->get_gp_seq();
490 }
491 }
492
493 jdone = jiffies + minruntime * HZ;
494 do {
495 if (writer_holdoff)
496 udelay(writer_holdoff);
497 if (writer_holdoff_jiffies)
498 schedule_timeout_idle(torture_random(&tr) % writer_holdoff_jiffies + 1);
499 wdp = &wdpp[i];
500 *wdp = ktime_get_mono_fast_ns();
501 if (gp_async) {
502retry:
503 if (!rhp)
504 rhp = kmalloc(sizeof(*rhp), GFP_KERNEL);
505 if (rhp && atomic_read(this_cpu_ptr(&n_async_inflight)) < gp_async_max) {
506 atomic_inc(this_cpu_ptr(&n_async_inflight));
507 cur_ops->async(rhp, rcu_scale_async_cb);
508 rhp = NULL;
509 } else if (!kthread_should_stop()) {
510 cur_ops->gp_barrier();
511 goto retry;
512 } else {
513 kfree(rhp); /* Because we are stopping. */
514 }
515 } else if (gp_exp) {
516 cur_ops->exp_sync();
517 } else {
518 cur_ops->sync();
519 }
520 t = ktime_get_mono_fast_ns();
521 *wdp = t - *wdp;
522 i_max = i;
523 if (!started &&
524 atomic_read(&n_rcu_scale_writer_started) >= nrealwriters)
525 started = true;
526 if (!done && i >= MIN_MEAS && time_after(jiffies, jdone)) {
527 done = true;
528 sched_set_normal(current, 0);
529 pr_alert("%s%s rcu_scale_writer %ld has %d measurements\n",
530 scale_type, SCALE_FLAG, me, MIN_MEAS);
531 if (atomic_inc_return(&n_rcu_scale_writer_finished) >=
532 nrealwriters) {
533 schedule_timeout_interruptible(10);
534 rcu_ftrace_dump(DUMP_ALL);
535 SCALEOUT_STRING("Test complete");
536 t_rcu_scale_writer_finished = t;
537 if (gp_exp) {
538 b_rcu_gp_test_finished =
539 cur_ops->exp_completed() / 2;
540 } else {
541 b_rcu_gp_test_finished =
542 cur_ops->get_gp_seq();
543 }
544 if (shutdown) {
545 smp_mb(); /* Assign before wake. */
546 wake_up(&shutdown_wq);
547 }
548 }
549 }
550 if (done && !alldone &&
551 atomic_read(&n_rcu_scale_writer_finished) >= nrealwriters)
552 alldone = true;
553 if (started && !alldone && i < MAX_MEAS - 1)
554 i++;
555 rcu_scale_wait_shutdown();
556 } while (!torture_must_stop());
557 if (gp_async) {
558 cur_ops->gp_barrier();
559 }
560 writer_n_durations[me] = i_max + 1;
561 torture_kthread_stopping("rcu_scale_writer");
562 return 0;
563}
564
565static void
566rcu_scale_print_module_parms(struct rcu_scale_ops *cur_ops, const char *tag)
567{
568 pr_alert("%s" SCALE_FLAG
569 "--- %s: gp_async=%d gp_async_max=%d gp_exp=%d holdoff=%d minruntime=%d nreaders=%d nwriters=%d writer_holdoff=%d writer_holdoff_jiffies=%d verbose=%d shutdown=%d\n",
570 scale_type, tag, gp_async, gp_async_max, gp_exp, holdoff, minruntime, nrealreaders, nrealwriters, writer_holdoff, writer_holdoff_jiffies, verbose, shutdown);
571}
572
573/*
574 * Return the number if non-negative. If -1, the number of CPUs.
575 * If less than -1, that much less than the number of CPUs, but
576 * at least one.
577 */
578static int compute_real(int n)
579{
580 int nr;
581
582 if (n >= 0) {
583 nr = n;
584 } else {
585 nr = num_online_cpus() + 1 + n;
586 if (nr <= 0)
587 nr = 1;
588 }
589 return nr;
590}
591
592/*
593 * kfree_rcu() scalability tests: Start a kfree_rcu() loop on all CPUs for number
594 * of iterations and measure total time and number of GP for all iterations to complete.
595 */
596
597torture_param(int, kfree_nthreads, -1, "Number of threads running loops of kfree_rcu().");
598torture_param(int, kfree_alloc_num, 8000, "Number of allocations and frees done in an iteration.");
599torture_param(int, kfree_loops, 10, "Number of loops doing kfree_alloc_num allocations and frees.");
600torture_param(bool, kfree_rcu_test_double, false, "Do we run a kfree_rcu() double-argument scale test?");
601torture_param(bool, kfree_rcu_test_single, false, "Do we run a kfree_rcu() single-argument scale test?");
602
603static struct task_struct **kfree_reader_tasks;
604static int kfree_nrealthreads;
605static atomic_t n_kfree_scale_thread_started;
606static atomic_t n_kfree_scale_thread_ended;
607static struct task_struct *kthread_tp;
608static u64 kthread_stime;
609
610struct kfree_obj {
611 char kfree_obj[8];
612 struct rcu_head rh;
613};
614
615/* Used if doing RCU-kfree'ing via call_rcu(). */
616static void kfree_call_rcu(struct rcu_head *rh)
617{
618 struct kfree_obj *obj = container_of(rh, struct kfree_obj, rh);
619
620 kfree(obj);
621}
622
623static int
624kfree_scale_thread(void *arg)
625{
626 int i, loop = 0;
627 long me = (long)arg;
628 struct kfree_obj *alloc_ptr;
629 u64 start_time, end_time;
630 long long mem_begin, mem_during = 0;
631 bool kfree_rcu_test_both;
632 DEFINE_TORTURE_RANDOM(tr);
633
634 VERBOSE_SCALEOUT_STRING("kfree_scale_thread task started");
635 set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
636 set_user_nice(current, MAX_NICE);
637 kfree_rcu_test_both = (kfree_rcu_test_single == kfree_rcu_test_double);
638
639 start_time = ktime_get_mono_fast_ns();
640
641 if (atomic_inc_return(&n_kfree_scale_thread_started) >= kfree_nrealthreads) {
642 if (gp_exp)
643 b_rcu_gp_test_started = cur_ops->exp_completed() / 2;
644 else
645 b_rcu_gp_test_started = cur_ops->get_gp_seq();
646 }
647
648 do {
649 if (!mem_during) {
650 mem_during = mem_begin = si_mem_available();
651 } else if (loop % (kfree_loops / 4) == 0) {
652 mem_during = (mem_during + si_mem_available()) / 2;
653 }
654
655 for (i = 0; i < kfree_alloc_num; i++) {
656 alloc_ptr = kmalloc(kfree_mult * sizeof(struct kfree_obj), GFP_KERNEL);
657 if (!alloc_ptr)
658 return -ENOMEM;
659
660 if (kfree_by_call_rcu) {
661 call_rcu(&(alloc_ptr->rh), kfree_call_rcu);
662 continue;
663 }
664
665 // By default kfree_rcu_test_single and kfree_rcu_test_double are
666 // initialized to false. If both have the same value (false or true)
667 // both are randomly tested, otherwise only the one with value true
668 // is tested.
669 if ((kfree_rcu_test_single && !kfree_rcu_test_double) ||
670 (kfree_rcu_test_both && torture_random(&tr) & 0x800))
671 kfree_rcu_mightsleep(alloc_ptr);
672 else
673 kfree_rcu(alloc_ptr, rh);
674 }
675
676 cond_resched();
677 } while (!torture_must_stop() && ++loop < kfree_loops);
678
679 if (atomic_inc_return(&n_kfree_scale_thread_ended) >= kfree_nrealthreads) {
680 end_time = ktime_get_mono_fast_ns();
681
682 if (gp_exp)
683 b_rcu_gp_test_finished = cur_ops->exp_completed() / 2;
684 else
685 b_rcu_gp_test_finished = cur_ops->get_gp_seq();
686
687 pr_alert("Total time taken by all kfree'ers: %llu ns, loops: %d, batches: %ld, memory footprint: %lldMB\n",
688 (unsigned long long)(end_time - start_time), kfree_loops,
689 rcuscale_seq_diff(b_rcu_gp_test_finished, b_rcu_gp_test_started),
690 (mem_begin - mem_during) >> (20 - PAGE_SHIFT));
691
692 if (shutdown) {
693 smp_mb(); /* Assign before wake. */
694 wake_up(&shutdown_wq);
695 }
696 }
697
698 torture_kthread_stopping("kfree_scale_thread");
699 return 0;
700}
701
702static void
703kfree_scale_cleanup(void)
704{
705 int i;
706
707 if (torture_cleanup_begin())
708 return;
709
710 if (kfree_reader_tasks) {
711 for (i = 0; i < kfree_nrealthreads; i++)
712 torture_stop_kthread(kfree_scale_thread,
713 kfree_reader_tasks[i]);
714 kfree(kfree_reader_tasks);
715 }
716
717 torture_cleanup_end();
718}
719
720/*
721 * shutdown kthread. Just waits to be awakened, then shuts down system.
722 */
723static int
724kfree_scale_shutdown(void *arg)
725{
726 wait_event_idle(shutdown_wq,
727 atomic_read(&n_kfree_scale_thread_ended) >= kfree_nrealthreads);
728
729 smp_mb(); /* Wake before output. */
730
731 kfree_scale_cleanup();
732 kernel_power_off();
733 return -EINVAL;
734}
735
736// Used if doing RCU-kfree'ing via call_rcu().
737static unsigned long jiffies_at_lazy_cb;
738static struct rcu_head lazy_test1_rh;
739static int rcu_lazy_test1_cb_called;
740static void call_rcu_lazy_test1(struct rcu_head *rh)
741{
742 jiffies_at_lazy_cb = jiffies;
743 WRITE_ONCE(rcu_lazy_test1_cb_called, 1);
744}
745
746static int __init
747kfree_scale_init(void)
748{
749 int firsterr = 0;
750 long i;
751 unsigned long jif_start;
752 unsigned long orig_jif;
753
754 pr_alert("%s" SCALE_FLAG
755 "--- kfree_rcu_test: kfree_mult=%d kfree_by_call_rcu=%d kfree_nthreads=%d kfree_alloc_num=%d kfree_loops=%d kfree_rcu_test_double=%d kfree_rcu_test_single=%d\n",
756 scale_type, kfree_mult, kfree_by_call_rcu, kfree_nthreads, kfree_alloc_num, kfree_loops, kfree_rcu_test_double, kfree_rcu_test_single);
757
758 // Also, do a quick self-test to ensure laziness is as much as
759 // expected.
760 if (kfree_by_call_rcu && !IS_ENABLED(CONFIG_RCU_LAZY)) {
761 pr_alert("CONFIG_RCU_LAZY is disabled, falling back to kfree_rcu() for delayed RCU kfree'ing\n");
762 kfree_by_call_rcu = 0;
763 }
764
765 if (kfree_by_call_rcu) {
766 /* do a test to check the timeout. */
767 orig_jif = rcu_lazy_get_jiffies_till_flush();
768
769 rcu_lazy_set_jiffies_till_flush(2 * HZ);
770 rcu_barrier();
771
772 jif_start = jiffies;
773 jiffies_at_lazy_cb = 0;
774 call_rcu(&lazy_test1_rh, call_rcu_lazy_test1);
775
776 smp_cond_load_relaxed(&rcu_lazy_test1_cb_called, VAL == 1);
777
778 rcu_lazy_set_jiffies_till_flush(orig_jif);
779
780 if (WARN_ON_ONCE(jiffies_at_lazy_cb - jif_start < 2 * HZ)) {
781 pr_alert("ERROR: call_rcu() CBs are not being lazy as expected!\n");
782 WARN_ON_ONCE(1);
783 return -1;
784 }
785
786 if (WARN_ON_ONCE(jiffies_at_lazy_cb - jif_start > 3 * HZ)) {
787 pr_alert("ERROR: call_rcu() CBs are being too lazy!\n");
788 WARN_ON_ONCE(1);
789 return -1;
790 }
791 }
792
793 kfree_nrealthreads = compute_real(kfree_nthreads);
794 /* Start up the kthreads. */
795 if (shutdown) {
796 init_waitqueue_head(&shutdown_wq);
797 firsterr = torture_create_kthread(kfree_scale_shutdown, NULL,
798 shutdown_task);
799 if (torture_init_error(firsterr))
800 goto unwind;
801 schedule_timeout_uninterruptible(1);
802 }
803
804 pr_alert("kfree object size=%zu, kfree_by_call_rcu=%d\n",
805 kfree_mult * sizeof(struct kfree_obj),
806 kfree_by_call_rcu);
807
808 kfree_reader_tasks = kcalloc(kfree_nrealthreads, sizeof(kfree_reader_tasks[0]),
809 GFP_KERNEL);
810 if (kfree_reader_tasks == NULL) {
811 firsterr = -ENOMEM;
812 goto unwind;
813 }
814
815 for (i = 0; i < kfree_nrealthreads; i++) {
816 firsterr = torture_create_kthread(kfree_scale_thread, (void *)i,
817 kfree_reader_tasks[i]);
818 if (torture_init_error(firsterr))
819 goto unwind;
820 }
821
822 while (atomic_read(&n_kfree_scale_thread_started) < kfree_nrealthreads)
823 schedule_timeout_uninterruptible(1);
824
825 torture_init_end();
826 return 0;
827
828unwind:
829 torture_init_end();
830 kfree_scale_cleanup();
831 return firsterr;
832}
833
834static void
835rcu_scale_cleanup(void)
836{
837 int i;
838 int j;
839 int ngps = 0;
840 u64 *wdp;
841 u64 *wdpp;
842
843 /*
844 * Would like warning at start, but everything is expedited
845 * during the mid-boot phase, so have to wait till the end.
846 */
847 if (rcu_gp_is_expedited() && !rcu_gp_is_normal() && !gp_exp)
848 SCALEOUT_ERRSTRING("All grace periods expedited, no normal ones to measure!");
849 if (rcu_gp_is_normal() && gp_exp)
850 SCALEOUT_ERRSTRING("All grace periods normal, no expedited ones to measure!");
851 if (gp_exp && gp_async)
852 SCALEOUT_ERRSTRING("No expedited async GPs, so went with async!");
853
854 // If built-in, just report all of the GP kthread's CPU time.
855 if (IS_BUILTIN(CONFIG_RCU_SCALE_TEST) && !kthread_tp && cur_ops->rso_gp_kthread)
856 kthread_tp = cur_ops->rso_gp_kthread();
857 if (kthread_tp) {
858 u32 ns;
859 u64 us;
860
861 kthread_stime = kthread_tp->stime - kthread_stime;
862 us = div_u64_rem(kthread_stime, 1000, &ns);
863 pr_info("rcu_scale: Grace-period kthread CPU time: %llu.%03u us\n", us, ns);
864 show_rcu_gp_kthreads();
865 }
866 if (kfree_rcu_test) {
867 kfree_scale_cleanup();
868 return;
869 }
870
871 if (torture_cleanup_begin())
872 return;
873 if (!cur_ops) {
874 torture_cleanup_end();
875 return;
876 }
877
878 if (reader_tasks) {
879 for (i = 0; i < nrealreaders; i++)
880 torture_stop_kthread(rcu_scale_reader,
881 reader_tasks[i]);
882 kfree(reader_tasks);
883 }
884
885 if (writer_tasks) {
886 for (i = 0; i < nrealwriters; i++) {
887 torture_stop_kthread(rcu_scale_writer,
888 writer_tasks[i]);
889 if (!writer_n_durations)
890 continue;
891 j = writer_n_durations[i];
892 pr_alert("%s%s writer %d gps: %d\n",
893 scale_type, SCALE_FLAG, i, j);
894 ngps += j;
895 }
896 pr_alert("%s%s start: %llu end: %llu duration: %llu gps: %d batches: %ld\n",
897 scale_type, SCALE_FLAG,
898 t_rcu_scale_writer_started, t_rcu_scale_writer_finished,
899 t_rcu_scale_writer_finished -
900 t_rcu_scale_writer_started,
901 ngps,
902 rcuscale_seq_diff(b_rcu_gp_test_finished,
903 b_rcu_gp_test_started));
904 for (i = 0; i < nrealwriters; i++) {
905 if (!writer_durations)
906 break;
907 if (!writer_n_durations)
908 continue;
909 wdpp = writer_durations[i];
910 if (!wdpp)
911 continue;
912 for (j = 0; j < writer_n_durations[i]; j++) {
913 wdp = &wdpp[j];
914 pr_alert("%s%s %4d writer-duration: %5d %llu\n",
915 scale_type, SCALE_FLAG,
916 i, j, *wdp);
917 if (j % 100 == 0)
918 schedule_timeout_uninterruptible(1);
919 }
920 kfree(writer_durations[i]);
921 }
922 kfree(writer_tasks);
923 kfree(writer_durations);
924 kfree(writer_n_durations);
925 }
926
927 /* Do torture-type-specific cleanup operations. */
928 if (cur_ops->cleanup != NULL)
929 cur_ops->cleanup();
930
931 torture_cleanup_end();
932}
933
934/*
935 * RCU scalability shutdown kthread. Just waits to be awakened, then shuts
936 * down system.
937 */
938static int
939rcu_scale_shutdown(void *arg)
940{
941 wait_event_idle(shutdown_wq, atomic_read(&n_rcu_scale_writer_finished) >= nrealwriters);
942 smp_mb(); /* Wake before output. */
943 rcu_scale_cleanup();
944 kernel_power_off();
945 return -EINVAL;
946}
947
948static int __init
949rcu_scale_init(void)
950{
951 long i;
952 int firsterr = 0;
953 static struct rcu_scale_ops *scale_ops[] = {
954 &rcu_ops, &srcu_ops, &srcud_ops, TASKS_OPS TASKS_RUDE_OPS TASKS_TRACING_OPS
955 };
956
957 if (!torture_init_begin(scale_type, verbose))
958 return -EBUSY;
959
960 /* Process args and announce that the scalability'er is on the job. */
961 for (i = 0; i < ARRAY_SIZE(scale_ops); i++) {
962 cur_ops = scale_ops[i];
963 if (strcmp(scale_type, cur_ops->name) == 0)
964 break;
965 }
966 if (i == ARRAY_SIZE(scale_ops)) {
967 pr_alert("rcu-scale: invalid scale type: \"%s\"\n", scale_type);
968 pr_alert("rcu-scale types:");
969 for (i = 0; i < ARRAY_SIZE(scale_ops); i++)
970 pr_cont(" %s", scale_ops[i]->name);
971 pr_cont("\n");
972 firsterr = -EINVAL;
973 cur_ops = NULL;
974 goto unwind;
975 }
976 if (cur_ops->init)
977 cur_ops->init();
978
979 if (cur_ops->rso_gp_kthread) {
980 kthread_tp = cur_ops->rso_gp_kthread();
981 if (kthread_tp)
982 kthread_stime = kthread_tp->stime;
983 }
984 if (kfree_rcu_test)
985 return kfree_scale_init();
986
987 nrealwriters = compute_real(nwriters);
988 nrealreaders = compute_real(nreaders);
989 atomic_set(&n_rcu_scale_reader_started, 0);
990 atomic_set(&n_rcu_scale_writer_started, 0);
991 atomic_set(&n_rcu_scale_writer_finished, 0);
992 rcu_scale_print_module_parms(cur_ops, "Start of test");
993
994 /* Start up the kthreads. */
995
996 if (shutdown) {
997 init_waitqueue_head(&shutdown_wq);
998 firsterr = torture_create_kthread(rcu_scale_shutdown, NULL,
999 shutdown_task);
1000 if (torture_init_error(firsterr))
1001 goto unwind;
1002 schedule_timeout_uninterruptible(1);
1003 }
1004 reader_tasks = kcalloc(nrealreaders, sizeof(reader_tasks[0]),
1005 GFP_KERNEL);
1006 if (reader_tasks == NULL) {
1007 SCALEOUT_ERRSTRING("out of memory");
1008 firsterr = -ENOMEM;
1009 goto unwind;
1010 }
1011 for (i = 0; i < nrealreaders; i++) {
1012 firsterr = torture_create_kthread(rcu_scale_reader, (void *)i,
1013 reader_tasks[i]);
1014 if (torture_init_error(firsterr))
1015 goto unwind;
1016 }
1017 while (atomic_read(&n_rcu_scale_reader_started) < nrealreaders)
1018 schedule_timeout_uninterruptible(1);
1019 writer_tasks = kcalloc(nrealwriters, sizeof(reader_tasks[0]),
1020 GFP_KERNEL);
1021 writer_durations = kcalloc(nrealwriters, sizeof(*writer_durations),
1022 GFP_KERNEL);
1023 writer_n_durations =
1024 kcalloc(nrealwriters, sizeof(*writer_n_durations),
1025 GFP_KERNEL);
1026 if (!writer_tasks || !writer_durations || !writer_n_durations) {
1027 SCALEOUT_ERRSTRING("out of memory");
1028 firsterr = -ENOMEM;
1029 goto unwind;
1030 }
1031 for (i = 0; i < nrealwriters; i++) {
1032 writer_durations[i] =
1033 kcalloc(MAX_MEAS, sizeof(*writer_durations[i]),
1034 GFP_KERNEL);
1035 if (!writer_durations[i]) {
1036 firsterr = -ENOMEM;
1037 goto unwind;
1038 }
1039 firsterr = torture_create_kthread(rcu_scale_writer, (void *)i,
1040 writer_tasks[i]);
1041 if (torture_init_error(firsterr))
1042 goto unwind;
1043 }
1044 torture_init_end();
1045 return 0;
1046
1047unwind:
1048 torture_init_end();
1049 rcu_scale_cleanup();
1050 if (shutdown) {
1051 WARN_ON(!IS_MODULE(CONFIG_RCU_SCALE_TEST));
1052 kernel_power_off();
1053 }
1054 return firsterr;
1055}
1056
1057module_init(rcu_scale_init);
1058module_exit(rcu_scale_cleanup);