2 * Read-Copy Update module-based torture test facility
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.
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.
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
18 * Copyright (C) IBM Corporation, 2005
20 * Authors: Paul E. McKenney <paulmck@us.ibm.com>
22 * See also: Documentation/RCU/torture.txt
24 #include <linux/types.h>
25 #include <linux/kernel.h>
26 #include <linux/init.h>
27 #include <linux/module.h>
28 #include <linux/kthread.h>
29 #include <linux/err.h>
30 #include <linux/spinlock.h>
31 #include <linux/smp.h>
32 #include <linux/rcupdate.h>
33 #include <linux/interrupt.h>
34 #include <linux/sched.h>
35 #include <asm/atomic.h>
36 #include <linux/bitops.h>
37 #include <linux/module.h>
38 #include <linux/completion.h>
39 #include <linux/moduleparam.h>
40 #include <linux/percpu.h>
41 #include <linux/notifier.h>
42 #include <linux/cpu.h>
43 #include <linux/random.h>
44 #include <linux/delay.h>
45 #include <linux/byteorder/swabb.h>
46 #include <linux/stat.h>
48 MODULE_LICENSE("GPL");
50 static int nreaders = -1; /* # reader threads, defaults to 4*ncpus */
51 static int stat_interval; /* Interval between stats, in seconds. */
52 /* Defaults to "only at end of test". */
53 static int verbose; /* Print more debug info. */
54 static int test_no_idle_hz; /* Test RCU's support for tickless idle CPUs. */
55 static int shuffle_interval = 5; /* Interval between shuffles (in sec)*/
56 static char *torture_type = "rcu"; /* What to torture. */
58 module_param(nreaders, int, 0);
59 MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
60 module_param(stat_interval, int, 0);
61 MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
62 module_param(verbose, bool, 0);
63 MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
64 module_param(test_no_idle_hz, bool, 0);
65 MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
66 module_param(shuffle_interval, int, 0);
67 MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
68 module_param(torture_type, charp, 0);
69 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu)");
71 #define TORTURE_FLAG "-torture:"
72 #define PRINTK_STRING(s) \
73 do { printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
74 #define VERBOSE_PRINTK_STRING(s) \
75 do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
76 #define VERBOSE_PRINTK_ERRSTRING(s) \
77 do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
79 static char printk_buf[4096];
81 static int nrealreaders;
82 static struct task_struct *writer_task;
83 static struct task_struct **reader_tasks;
84 static struct task_struct *stats_task;
85 static struct task_struct *shuffler_task;
87 #define RCU_TORTURE_PIPE_LEN 10
90 struct rcu_head rtort_rcu;
92 struct list_head rtort_free;
96 static int fullstop = 0; /* stop generating callbacks at test end. */
97 static LIST_HEAD(rcu_torture_freelist);
98 static struct rcu_torture *rcu_torture_current = NULL;
99 static long rcu_torture_current_version = 0;
100 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
101 static DEFINE_SPINLOCK(rcu_torture_lock);
102 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
104 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) =
106 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
107 atomic_t n_rcu_torture_alloc;
108 atomic_t n_rcu_torture_alloc_fail;
109 atomic_t n_rcu_torture_free;
110 atomic_t n_rcu_torture_mberror;
111 atomic_t n_rcu_torture_error;
114 * Allocate an element from the rcu_tortures pool.
116 static struct rcu_torture *
117 rcu_torture_alloc(void)
121 spin_lock_bh(&rcu_torture_lock);
122 if (list_empty(&rcu_torture_freelist)) {
123 atomic_inc(&n_rcu_torture_alloc_fail);
124 spin_unlock_bh(&rcu_torture_lock);
127 atomic_inc(&n_rcu_torture_alloc);
128 p = rcu_torture_freelist.next;
130 spin_unlock_bh(&rcu_torture_lock);
131 return container_of(p, struct rcu_torture, rtort_free);
135 * Free an element to the rcu_tortures pool.
138 rcu_torture_free(struct rcu_torture *p)
140 atomic_inc(&n_rcu_torture_free);
141 spin_lock_bh(&rcu_torture_lock);
142 list_add_tail(&p->rtort_free, &rcu_torture_freelist);
143 spin_unlock_bh(&rcu_torture_lock);
146 struct rcu_random_state {
147 unsigned long rrs_state;
148 unsigned long rrs_count;
151 #define RCU_RANDOM_MULT 39916801 /* prime */
152 #define RCU_RANDOM_ADD 479001701 /* prime */
153 #define RCU_RANDOM_REFRESH 10000
155 #define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
158 * Crude but fast random-number generator. Uses a linear congruential
159 * generator, with occasional help from get_random_bytes().
162 rcu_random(struct rcu_random_state *rrsp)
166 if (--rrsp->rrs_count < 0) {
167 get_random_bytes(&refresh, sizeof(refresh));
168 rrsp->rrs_state += refresh;
169 rrsp->rrs_count = RCU_RANDOM_REFRESH;
171 rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
172 return swahw32(rrsp->rrs_state);
176 * Operations vector for selecting different types of tests.
179 struct rcu_torture_ops {
181 void (*cleanup)(void);
182 int (*readlock)(void);
183 void (*readunlock)(int idx);
184 int (*completed)(void);
185 void (*deferredfree)(struct rcu_torture *p);
186 int (*stats)(char *page);
189 static struct rcu_torture_ops *cur_ops = NULL;
192 * Definitions for rcu torture testing.
195 static int rcu_torture_read_lock(void)
201 static void rcu_torture_read_unlock(int idx)
206 static int rcu_torture_completed(void)
208 return rcu_batches_completed();
212 rcu_torture_cb(struct rcu_head *p)
215 struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
218 /* Test is ending, just drop callbacks on the floor. */
219 /* The next initialization will pick up the pieces. */
222 i = rp->rtort_pipe_count;
223 if (i > RCU_TORTURE_PIPE_LEN)
224 i = RCU_TORTURE_PIPE_LEN;
225 atomic_inc(&rcu_torture_wcount[i]);
226 if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
227 rp->rtort_mbtest = 0;
228 rcu_torture_free(rp);
230 cur_ops->deferredfree(rp);
233 static void rcu_torture_deferred_free(struct rcu_torture *p)
235 call_rcu(&p->rtort_rcu, rcu_torture_cb);
238 static struct rcu_torture_ops rcu_ops = {
241 .readlock = rcu_torture_read_lock,
242 .readunlock = rcu_torture_read_unlock,
243 .completed = rcu_torture_completed,
244 .deferredfree = rcu_torture_deferred_free,
249 static struct rcu_torture_ops *torture_ops[] =
253 * RCU torture writer kthread. Repeatedly substitutes a new structure
254 * for that pointed to by rcu_torture_current, freeing the old structure
255 * after a series of grace periods (the "pipeline").
258 rcu_torture_writer(void *arg)
261 long oldbatch = rcu_batches_completed();
262 struct rcu_torture *rp;
263 struct rcu_torture *old_rp;
264 static DEFINE_RCU_RANDOM(rand);
266 VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
267 set_user_nice(current, 19);
270 schedule_timeout_uninterruptible(1);
271 if ((rp = rcu_torture_alloc()) == NULL)
273 rp->rtort_pipe_count = 0;
274 udelay(rcu_random(&rand) & 0x3ff);
275 old_rp = rcu_torture_current;
276 rp->rtort_mbtest = 1;
277 rcu_assign_pointer(rcu_torture_current, rp);
279 if (old_rp != NULL) {
280 i = old_rp->rtort_pipe_count;
281 if (i > RCU_TORTURE_PIPE_LEN)
282 i = RCU_TORTURE_PIPE_LEN;
283 atomic_inc(&rcu_torture_wcount[i]);
284 old_rp->rtort_pipe_count++;
285 cur_ops->deferredfree(old_rp);
287 rcu_torture_current_version++;
288 oldbatch = cur_ops->completed();
289 } while (!kthread_should_stop() && !fullstop);
290 VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
291 while (!kthread_should_stop())
292 schedule_timeout_uninterruptible(1);
297 * RCU torture reader kthread. Repeatedly dereferences rcu_torture_current,
298 * incrementing the corresponding element of the pipeline array. The
299 * counter in the element should never be greater than 1, otherwise, the
300 * RCU implementation is broken.
303 rcu_torture_reader(void *arg)
307 DEFINE_RCU_RANDOM(rand);
308 struct rcu_torture *p;
311 VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
312 set_user_nice(current, 19);
315 idx = cur_ops->readlock();
316 completed = cur_ops->completed();
317 p = rcu_dereference(rcu_torture_current);
319 /* Wait for rcu_torture_writer to get underway */
320 cur_ops->readunlock(idx);
321 schedule_timeout_interruptible(HZ);
324 if (p->rtort_mbtest == 0)
325 atomic_inc(&n_rcu_torture_mberror);
326 udelay(rcu_random(&rand) & 0x7f);
328 pipe_count = p->rtort_pipe_count;
329 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
330 /* Should not happen, but... */
331 pipe_count = RCU_TORTURE_PIPE_LEN;
333 ++__get_cpu_var(rcu_torture_count)[pipe_count];
334 completed = cur_ops->completed() - completed;
335 if (completed > RCU_TORTURE_PIPE_LEN) {
336 /* Should not happen, but... */
337 completed = RCU_TORTURE_PIPE_LEN;
339 ++__get_cpu_var(rcu_torture_batch)[completed];
341 cur_ops->readunlock(idx);
343 } while (!kthread_should_stop() && !fullstop);
344 VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
345 while (!kthread_should_stop())
346 schedule_timeout_uninterruptible(1);
351 * Create an RCU-torture statistics message in the specified buffer.
354 rcu_torture_printk(char *page)
359 long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
360 long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
362 for_each_possible_cpu(cpu) {
363 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
364 pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
365 batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
368 for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
369 if (pipesummary[i] != 0)
372 cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
373 cnt += sprintf(&page[cnt],
374 "rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d "
377 rcu_torture_current_version,
378 list_empty(&rcu_torture_freelist),
379 atomic_read(&n_rcu_torture_alloc),
380 atomic_read(&n_rcu_torture_alloc_fail),
381 atomic_read(&n_rcu_torture_free),
382 atomic_read(&n_rcu_torture_mberror));
383 if (atomic_read(&n_rcu_torture_mberror) != 0)
384 cnt += sprintf(&page[cnt], " !!!");
385 cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
387 cnt += sprintf(&page[cnt], "!!! ");
388 atomic_inc(&n_rcu_torture_error);
390 cnt += sprintf(&page[cnt], "Reader Pipe: ");
391 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
392 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
393 cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
394 cnt += sprintf(&page[cnt], "Reader Batch: ");
395 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
396 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
397 cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
398 cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
399 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
400 cnt += sprintf(&page[cnt], " %d",
401 atomic_read(&rcu_torture_wcount[i]));
403 cnt += sprintf(&page[cnt], "\n");
404 if (cur_ops->stats != NULL)
405 cnt += cur_ops->stats(&page[cnt]);
410 * Print torture statistics. Caller must ensure that there is only
411 * one call to this function at a given time!!! This is normally
412 * accomplished by relying on the module system to only have one copy
413 * of the module loaded, and then by giving the rcu_torture_stats
414 * kthread full control (or the init/cleanup functions when rcu_torture_stats
415 * thread is not running).
418 rcu_torture_stats_print(void)
422 cnt = rcu_torture_printk(printk_buf);
423 printk(KERN_ALERT "%s", printk_buf);
427 * Periodically prints torture statistics, if periodic statistics printing
428 * was specified via the stat_interval module parameter.
430 * No need to worry about fullstop here, since this one doesn't reference
431 * volatile state or register callbacks.
434 rcu_torture_stats(void *arg)
436 VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
438 schedule_timeout_interruptible(stat_interval * HZ);
439 rcu_torture_stats_print();
440 } while (!kthread_should_stop());
441 VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
445 static int rcu_idle_cpu; /* Force all torture tasks off this CPU */
447 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
448 * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
450 void rcu_torture_shuffle_tasks(void)
452 cpumask_t tmp_mask = CPU_MASK_ALL;
457 /* No point in shuffling if there is only one online CPU (ex: UP) */
458 if (num_online_cpus() == 1) {
459 unlock_cpu_hotplug();
463 if (rcu_idle_cpu != -1)
464 cpu_clear(rcu_idle_cpu, tmp_mask);
466 set_cpus_allowed(current, tmp_mask);
468 if (reader_tasks != NULL) {
469 for (i = 0; i < nrealreaders; i++)
471 set_cpus_allowed(reader_tasks[i], tmp_mask);
475 set_cpus_allowed(writer_task, tmp_mask);
478 set_cpus_allowed(stats_task, tmp_mask);
480 if (rcu_idle_cpu == -1)
481 rcu_idle_cpu = num_online_cpus() - 1;
485 unlock_cpu_hotplug();
488 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
489 * system to become idle at a time and cut off its timer ticks. This is meant
490 * to test the support for such tickless idle CPU in RCU.
493 rcu_torture_shuffle(void *arg)
495 VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
497 schedule_timeout_interruptible(shuffle_interval * HZ);
498 rcu_torture_shuffle_tasks();
499 } while (!kthread_should_stop());
500 VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
505 rcu_torture_print_module_parms(char *tag)
507 printk(KERN_ALERT "%s" TORTURE_FLAG "--- %s: nreaders=%d "
508 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
509 "shuffle_interval = %d\n",
510 torture_type, tag, nrealreaders, stat_interval, verbose,
511 test_no_idle_hz, shuffle_interval);
515 rcu_torture_cleanup(void)
520 if (shuffler_task != NULL) {
521 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
522 kthread_stop(shuffler_task);
524 shuffler_task = NULL;
526 if (writer_task != NULL) {
527 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
528 kthread_stop(writer_task);
532 if (reader_tasks != NULL) {
533 for (i = 0; i < nrealreaders; i++) {
534 if (reader_tasks[i] != NULL) {
535 VERBOSE_PRINTK_STRING(
536 "Stopping rcu_torture_reader task");
537 kthread_stop(reader_tasks[i]);
539 reader_tasks[i] = NULL;
544 rcu_torture_current = NULL;
546 if (stats_task != NULL) {
547 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
548 kthread_stop(stats_task);
552 /* Wait for all RCU callbacks to fire. */
555 rcu_torture_stats_print(); /* -After- the stats thread is stopped! */
557 if (cur_ops->cleanup != NULL)
559 if (atomic_read(&n_rcu_torture_error))
560 rcu_torture_print_module_parms("End of test: FAILURE");
562 rcu_torture_print_module_parms("End of test: SUCCESS");
566 rcu_torture_init(void)
572 /* Process args and tell the world that the torturer is on the job. */
574 for (i = 0; cur_ops = torture_ops[i], cur_ops != NULL; i++) {
575 cur_ops = torture_ops[i];
576 if (strcmp(torture_type, cur_ops->name) == 0) {
580 if (cur_ops == NULL) {
581 printk(KERN_ALERT "rcutorture: invalid torture type: \"%s\"\n",
585 if (cur_ops->init != NULL)
586 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
589 nrealreaders = nreaders;
591 nrealreaders = 2 * num_online_cpus();
592 rcu_torture_print_module_parms("Start of test");
595 /* Set up the freelist. */
597 INIT_LIST_HEAD(&rcu_torture_freelist);
598 for (i = 0; i < sizeof(rcu_tortures) / sizeof(rcu_tortures[0]); i++) {
599 rcu_tortures[i].rtort_mbtest = 0;
600 list_add_tail(&rcu_tortures[i].rtort_free,
601 &rcu_torture_freelist);
604 /* Initialize the statistics so that each run gets its own numbers. */
606 rcu_torture_current = NULL;
607 rcu_torture_current_version = 0;
608 atomic_set(&n_rcu_torture_alloc, 0);
609 atomic_set(&n_rcu_torture_alloc_fail, 0);
610 atomic_set(&n_rcu_torture_free, 0);
611 atomic_set(&n_rcu_torture_mberror, 0);
612 atomic_set(&n_rcu_torture_error, 0);
613 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
614 atomic_set(&rcu_torture_wcount[i], 0);
615 for_each_possible_cpu(cpu) {
616 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
617 per_cpu(rcu_torture_count, cpu)[i] = 0;
618 per_cpu(rcu_torture_batch, cpu)[i] = 0;
622 /* Start up the kthreads. */
624 VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
625 writer_task = kthread_run(rcu_torture_writer, NULL,
626 "rcu_torture_writer");
627 if (IS_ERR(writer_task)) {
628 firsterr = PTR_ERR(writer_task);
629 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
633 reader_tasks = kmalloc(nrealreaders * sizeof(reader_tasks[0]),
635 if (reader_tasks == NULL) {
636 VERBOSE_PRINTK_ERRSTRING("out of memory");
640 for (i = 0; i < nrealreaders; i++) {
641 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
642 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
643 "rcu_torture_reader");
644 if (IS_ERR(reader_tasks[i])) {
645 firsterr = PTR_ERR(reader_tasks[i]);
646 VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
647 reader_tasks[i] = NULL;
651 if (stat_interval > 0) {
652 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
653 stats_task = kthread_run(rcu_torture_stats, NULL,
654 "rcu_torture_stats");
655 if (IS_ERR(stats_task)) {
656 firsterr = PTR_ERR(stats_task);
657 VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
662 if (test_no_idle_hz) {
663 rcu_idle_cpu = num_online_cpus() - 1;
664 /* Create the shuffler thread */
665 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
666 "rcu_torture_shuffle");
667 if (IS_ERR(shuffler_task)) {
668 firsterr = PTR_ERR(shuffler_task);
669 VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
670 shuffler_task = NULL;
677 rcu_torture_cleanup();
681 module_init(rcu_torture_init);
682 module_exit(rcu_torture_cleanup);