2 * Read-Copy Update /proc-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
= 0; /* Interval between stats, in seconds. */
52 /* Defaults to "only at end of test". */
53 static int verbose
= 0; /* Print more debug info. */
55 MODULE_PARM(nreaders
, "i");
56 MODULE_PARM_DESC(nreaders
, "Number of RCU reader threads");
57 MODULE_PARM(stat_interval
, "i");
58 MODULE_PARM_DESC(stat_interval
, "Number of seconds between stats printk()s");
59 MODULE_PARM(verbose
, "i");
60 MODULE_PARM_DESC(verbose
, "Enable verbose debugging printk()s");
61 #define TORTURE_FLAG "rcutorture: "
62 #define PRINTK_STRING(s) \
63 do { printk(KERN_ALERT TORTURE_FLAG s "\n"); } while (0)
64 #define VERBOSE_PRINTK_STRING(s) \
65 do { if (verbose) printk(KERN_ALERT TORTURE_FLAG s "\n"); } while (0)
66 #define VERBOSE_PRINTK_ERRSTRING(s) \
67 do { if (verbose) printk(KERN_ALERT TORTURE_FLAG "!!! " s "\n"); } while (0)
69 static char printk_buf
[4096];
71 static int nrealreaders
;
72 static struct task_struct
*writer_task
;
73 static struct task_struct
**reader_tasks
;
74 static struct task_struct
*stats_task
;
76 #define RCU_TORTURE_PIPE_LEN 10
79 struct rcu_head rtort_rcu
;
81 struct list_head rtort_free
;
85 static int fullstop
= 0; /* stop generating callbacks at test end. */
86 static LIST_HEAD(rcu_torture_freelist
);
87 static struct rcu_torture
*rcu_torture_current
= NULL
;
88 static long rcu_torture_current_version
= 0;
89 static struct rcu_torture rcu_tortures
[10 * RCU_TORTURE_PIPE_LEN
];
90 static DEFINE_SPINLOCK(rcu_torture_lock
);
91 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN
+ 1], rcu_torture_count
) =
93 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN
+ 1], rcu_torture_batch
) =
95 static atomic_t rcu_torture_wcount
[RCU_TORTURE_PIPE_LEN
+ 1];
96 atomic_t n_rcu_torture_alloc
;
97 atomic_t n_rcu_torture_alloc_fail
;
98 atomic_t n_rcu_torture_free
;
99 atomic_t n_rcu_torture_mberror
;
100 atomic_t n_rcu_torture_error
;
103 * Allocate an element from the rcu_tortures pool.
105 static struct rcu_torture
*
106 rcu_torture_alloc(void)
110 spin_lock(&rcu_torture_lock
);
111 if (list_empty(&rcu_torture_freelist
)) {
112 atomic_inc(&n_rcu_torture_alloc_fail
);
113 spin_unlock(&rcu_torture_lock
);
116 atomic_inc(&n_rcu_torture_alloc
);
117 p
= rcu_torture_freelist
.next
;
119 spin_unlock(&rcu_torture_lock
);
120 return container_of(p
, struct rcu_torture
, rtort_free
);
124 * Free an element to the rcu_tortures pool.
127 rcu_torture_free(struct rcu_torture
*p
)
129 atomic_inc(&n_rcu_torture_free
);
130 spin_lock(&rcu_torture_lock
);
131 list_add_tail(&p
->rtort_free
, &rcu_torture_freelist
);
132 spin_unlock(&rcu_torture_lock
);
136 rcu_torture_cb(struct rcu_head
*p
)
139 struct rcu_torture
*rp
= container_of(p
, struct rcu_torture
, rtort_rcu
);
142 /* Test is ending, just drop callbacks on the floor. */
143 /* The next initialization will pick up the pieces. */
146 i
= rp
->rtort_pipe_count
;
147 if (i
> RCU_TORTURE_PIPE_LEN
)
148 i
= RCU_TORTURE_PIPE_LEN
;
149 atomic_inc(&rcu_torture_wcount
[i
]);
150 if (++rp
->rtort_pipe_count
>= RCU_TORTURE_PIPE_LEN
) {
151 rp
->rtort_mbtest
= 0;
152 rcu_torture_free(rp
);
154 call_rcu(p
, rcu_torture_cb
);
157 struct rcu_random_state
{
158 unsigned long rrs_state
;
159 unsigned long rrs_count
;
162 #define RCU_RANDOM_MULT 39916801 /* prime */
163 #define RCU_RANDOM_ADD 479001701 /* prime */
164 #define RCU_RANDOM_REFRESH 10000
166 #define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
169 * Crude but fast random-number generator. Uses a linear congruential
170 * generator, with occasional help from get_random_bytes().
173 rcu_random(struct rcu_random_state
*rrsp
)
177 if (--rrsp
->rrs_count
< 0) {
178 get_random_bytes(&refresh
, sizeof(refresh
));
179 rrsp
->rrs_state
+= refresh
;
180 rrsp
->rrs_count
= RCU_RANDOM_REFRESH
;
182 rrsp
->rrs_state
= rrsp
->rrs_state
* RCU_RANDOM_MULT
+ RCU_RANDOM_ADD
;
183 return swahw32(rrsp
->rrs_state
);
187 * RCU torture writer kthread. Repeatedly substitutes a new structure
188 * for that pointed to by rcu_torture_current, freeing the old structure
189 * after a series of grace periods (the "pipeline").
192 rcu_torture_writer(void *arg
)
195 long oldbatch
= rcu_batches_completed();
196 struct rcu_torture
*rp
;
197 struct rcu_torture
*old_rp
;
198 static DEFINE_RCU_RANDOM(rand
);
200 VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
201 set_user_nice(current
, 19);
204 schedule_timeout_uninterruptible(1);
205 if (rcu_batches_completed() == oldbatch
)
207 if ((rp
= rcu_torture_alloc()) == NULL
)
209 rp
->rtort_pipe_count
= 0;
210 udelay(rcu_random(&rand
) & 0x3ff);
211 old_rp
= rcu_torture_current
;
212 rp
->rtort_mbtest
= 1;
213 rcu_assign_pointer(rcu_torture_current
, rp
);
215 if (old_rp
!= NULL
) {
216 i
= old_rp
->rtort_pipe_count
;
217 if (i
> RCU_TORTURE_PIPE_LEN
)
218 i
= RCU_TORTURE_PIPE_LEN
;
219 atomic_inc(&rcu_torture_wcount
[i
]);
220 old_rp
->rtort_pipe_count
++;
221 call_rcu(&old_rp
->rtort_rcu
, rcu_torture_cb
);
223 rcu_torture_current_version
++;
224 oldbatch
= rcu_batches_completed();
225 } while (!kthread_should_stop() && !fullstop
);
226 VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
227 while (!kthread_should_stop())
228 schedule_timeout_uninterruptible(1);
233 * RCU torture reader kthread. Repeatedly dereferences rcu_torture_current,
234 * incrementing the corresponding element of the pipeline array. The
235 * counter in the element should never be greater than 1, otherwise, the
236 * RCU implementation is broken.
239 rcu_torture_reader(void *arg
)
242 DEFINE_RCU_RANDOM(rand
);
243 struct rcu_torture
*p
;
246 VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
247 set_user_nice(current
, 19);
251 completed
= rcu_batches_completed();
252 p
= rcu_dereference(rcu_torture_current
);
254 /* Wait for rcu_torture_writer to get underway */
256 schedule_timeout_interruptible(HZ
);
259 if (p
->rtort_mbtest
== 0)
260 atomic_inc(&n_rcu_torture_mberror
);
261 udelay(rcu_random(&rand
) & 0x7f);
263 pipe_count
= p
->rtort_pipe_count
;
264 if (pipe_count
> RCU_TORTURE_PIPE_LEN
) {
265 /* Should not happen, but... */
266 pipe_count
= RCU_TORTURE_PIPE_LEN
;
268 ++__get_cpu_var(rcu_torture_count
)[pipe_count
];
269 completed
= rcu_batches_completed() - completed
;
270 if (completed
> RCU_TORTURE_PIPE_LEN
) {
271 /* Should not happen, but... */
272 completed
= RCU_TORTURE_PIPE_LEN
;
274 ++__get_cpu_var(rcu_torture_batch
)[completed
];
278 } while (!kthread_should_stop() && !fullstop
);
279 VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
280 while (!kthread_should_stop())
281 schedule_timeout_uninterruptible(1);
286 * Create an RCU-torture statistics message in the specified buffer.
289 rcu_torture_printk(char *page
)
294 long pipesummary
[RCU_TORTURE_PIPE_LEN
+ 1] = { 0 };
295 long batchsummary
[RCU_TORTURE_PIPE_LEN
+ 1] = { 0 };
298 for (i
= 0; i
< RCU_TORTURE_PIPE_LEN
+ 1; i
++) {
299 pipesummary
[i
] += per_cpu(rcu_torture_count
, cpu
)[i
];
300 batchsummary
[i
] += per_cpu(rcu_torture_batch
, cpu
)[i
];
303 for (i
= RCU_TORTURE_PIPE_LEN
- 1; i
>= 0; i
--) {
304 if (pipesummary
[i
] != 0)
307 cnt
+= sprintf(&page
[cnt
], "rcutorture: ");
308 cnt
+= sprintf(&page
[cnt
],
309 "rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d "
312 rcu_torture_current_version
,
313 list_empty(&rcu_torture_freelist
),
314 atomic_read(&n_rcu_torture_alloc
),
315 atomic_read(&n_rcu_torture_alloc_fail
),
316 atomic_read(&n_rcu_torture_free
),
317 atomic_read(&n_rcu_torture_mberror
));
318 if (atomic_read(&n_rcu_torture_mberror
) != 0)
319 cnt
+= sprintf(&page
[cnt
], " !!!");
320 cnt
+= sprintf(&page
[cnt
], "\nrcutorture: ");
322 cnt
+= sprintf(&page
[cnt
], "!!! ");
323 atomic_inc(&n_rcu_torture_error
);
325 cnt
+= sprintf(&page
[cnt
], "Reader Pipe: ");
326 for (i
= 0; i
< RCU_TORTURE_PIPE_LEN
+ 1; i
++)
327 cnt
+= sprintf(&page
[cnt
], " %ld", pipesummary
[i
]);
328 cnt
+= sprintf(&page
[cnt
], "\nrcutorture: ");
329 cnt
+= sprintf(&page
[cnt
], "Reader Batch: ");
330 for (i
= 0; i
< RCU_TORTURE_PIPE_LEN
; i
++)
331 cnt
+= sprintf(&page
[cnt
], " %ld", batchsummary
[i
]);
332 cnt
+= sprintf(&page
[cnt
], "\nrcutorture: ");
333 cnt
+= sprintf(&page
[cnt
], "Free-Block Circulation: ");
334 for (i
= 0; i
< RCU_TORTURE_PIPE_LEN
+ 1; i
++) {
335 cnt
+= sprintf(&page
[cnt
], " %d",
336 atomic_read(&rcu_torture_wcount
[i
]));
338 cnt
+= sprintf(&page
[cnt
], "\n");
343 * Print torture statistics. Caller must ensure that there is only
344 * one call to this function at a given time!!! This is normally
345 * accomplished by relying on the module system to only have one copy
346 * of the module loaded, and then by giving the rcu_torture_stats
347 * kthread full control (or the init/cleanup functions when rcu_torture_stats
348 * thread is not running).
351 rcu_torture_stats_print(void)
355 cnt
= rcu_torture_printk(printk_buf
);
356 printk(KERN_ALERT
"%s", printk_buf
);
360 * Periodically prints torture statistics, if periodic statistics printing
361 * was specified via the stat_interval module parameter.
363 * No need to worry about fullstop here, since this one doesn't reference
364 * volatile state or register callbacks.
367 rcu_torture_stats(void *arg
)
369 VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
371 schedule_timeout_interruptible(stat_interval
* HZ
);
372 rcu_torture_stats_print();
373 } while (!kthread_should_stop());
374 VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
379 rcu_torture_cleanup(void)
384 if (writer_task
!= NULL
) {
385 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
386 kthread_stop(writer_task
);
390 if (reader_tasks
!= NULL
) {
391 for (i
= 0; i
< nrealreaders
; i
++) {
392 if (reader_tasks
[i
] != NULL
) {
393 VERBOSE_PRINTK_STRING(
394 "Stopping rcu_torture_reader task");
395 kthread_stop(reader_tasks
[i
]);
397 reader_tasks
[i
] = NULL
;
402 rcu_torture_current
= NULL
;
404 if (stats_task
!= NULL
) {
405 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
406 kthread_stop(stats_task
);
410 /* Wait for all RCU callbacks to fire. */
413 rcu_torture_stats_print(); /* -After- the stats thread is stopped! */
414 printk(KERN_ALERT TORTURE_FLAG
415 "--- End of test: %s\n",
416 atomic_read(&n_rcu_torture_error
) == 0 ? "SUCCESS" : "FAILURE");
420 rcu_torture_init(void)
426 /* Process args and tell the world that the torturer is on the job. */
429 nrealreaders
= nreaders
;
431 nrealreaders
= 2 * num_online_cpus();
432 printk(KERN_ALERT TORTURE_FLAG
433 "--- Start of test: nreaders=%d stat_interval=%d verbose=%d\n",
434 nrealreaders
, stat_interval
, verbose
);
437 /* Set up the freelist. */
439 INIT_LIST_HEAD(&rcu_torture_freelist
);
440 for (i
= 0; i
< sizeof(rcu_tortures
) / sizeof(rcu_tortures
[0]); i
++) {
441 rcu_tortures
[i
].rtort_mbtest
= 0;
442 list_add_tail(&rcu_tortures
[i
].rtort_free
,
443 &rcu_torture_freelist
);
446 /* Initialize the statistics so that each run gets its own numbers. */
448 rcu_torture_current
= NULL
;
449 rcu_torture_current_version
= 0;
450 atomic_set(&n_rcu_torture_alloc
, 0);
451 atomic_set(&n_rcu_torture_alloc_fail
, 0);
452 atomic_set(&n_rcu_torture_free
, 0);
453 atomic_set(&n_rcu_torture_mberror
, 0);
454 atomic_set(&n_rcu_torture_error
, 0);
455 for (i
= 0; i
< RCU_TORTURE_PIPE_LEN
+ 1; i
++)
456 atomic_set(&rcu_torture_wcount
[i
], 0);
458 for (i
= 0; i
< RCU_TORTURE_PIPE_LEN
+ 1; i
++) {
459 per_cpu(rcu_torture_count
, cpu
)[i
] = 0;
460 per_cpu(rcu_torture_batch
, cpu
)[i
] = 0;
464 /* Start up the kthreads. */
466 VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
467 writer_task
= kthread_run(rcu_torture_writer
, NULL
,
468 "rcu_torture_writer");
469 if (IS_ERR(writer_task
)) {
470 firsterr
= PTR_ERR(writer_task
);
471 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
475 reader_tasks
= kmalloc(nrealreaders
* sizeof(reader_tasks
[0]),
477 if (reader_tasks
== NULL
) {
478 VERBOSE_PRINTK_ERRSTRING("out of memory");
482 for (i
= 0; i
< nrealreaders
; i
++) {
483 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
484 reader_tasks
[i
] = kthread_run(rcu_torture_reader
, NULL
,
485 "rcu_torture_reader");
486 if (IS_ERR(reader_tasks
[i
])) {
487 firsterr
= PTR_ERR(reader_tasks
[i
]);
488 VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
489 reader_tasks
[i
] = NULL
;
493 if (stat_interval
> 0) {
494 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
495 stats_task
= kthread_run(rcu_torture_stats
, NULL
,
496 "rcu_torture_stats");
497 if (IS_ERR(stats_task
)) {
498 firsterr
= PTR_ERR(stats_task
);
499 VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
507 rcu_torture_cleanup();
511 module_init(rcu_torture_init
);
512 module_exit(rcu_torture_cleanup
);