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1 | /* |
2 | * Read-Copy Update /proc-based torture test facility | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or modify | |
5 | * it under the terms of the GNU General Public License as published by | |
6 | * the Free Software Foundation; either version 2 of the License, or | |
7 | * (at your option) any later version. | |
8 | * | |
9 | * This program is distributed in the hope that it will be useful, | |
10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
12 | * GNU General Public License for more details. | |
13 | * | |
14 | * You should have received a copy of the GNU General Public License | |
15 | * along with this program; if not, write to the Free Software | |
16 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. | |
17 | * | |
18 | * Copyright (C) IBM Corporation, 2005 | |
19 | * | |
20 | * Authors: Paul E. McKenney <paulmck@us.ibm.com> | |
21 | * | |
22 | * See also: Documentation/RCU/torture.txt | |
23 | */ | |
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/rcuref.h> | |
43 | #include <linux/cpu.h> | |
44 | #include <linux/random.h> | |
45 | #include <linux/delay.h> | |
46 | #include <linux/byteorder/swabb.h> | |
47 | #include <linux/stat.h> | |
48 | ||
49 | MODULE_LICENSE("GPL"); | |
50 | ||
51 | static int nreaders = -1; /* # reader threads, defaults to 4*ncpus */ | |
52 | static int stat_interval = 0; /* Interval between stats, in seconds. */ | |
53 | /* Defaults to "only at end of test". */ | |
54 | static int verbose = 0; /* Print more debug info. */ | |
55 | ||
56 | MODULE_PARM(nreaders, "i"); | |
57 | MODULE_PARM_DESC(nreaders, "Number of RCU reader threads"); | |
58 | MODULE_PARM(stat_interval, "i"); | |
59 | MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s"); | |
60 | MODULE_PARM(verbose, "i"); | |
61 | MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s"); | |
62 | #define TORTURE_FLAG "rcutorture: " | |
63 | #define PRINTK_STRING(s) \ | |
64 | do { printk(KERN_ALERT TORTURE_FLAG s "\n"); } while (0) | |
65 | #define VERBOSE_PRINTK_STRING(s) \ | |
66 | do { if (verbose) printk(KERN_ALERT TORTURE_FLAG s "\n"); } while (0) | |
67 | #define VERBOSE_PRINTK_ERRSTRING(s) \ | |
68 | do { if (verbose) printk(KERN_ALERT TORTURE_FLAG "!!! " s "\n"); } while (0) | |
69 | ||
70 | static char printk_buf[4096]; | |
71 | ||
72 | static int nrealreaders; | |
73 | static struct task_struct *writer_task; | |
74 | static struct task_struct **reader_tasks; | |
75 | static struct task_struct *stats_task; | |
76 | ||
77 | #define RCU_TORTURE_PIPE_LEN 10 | |
78 | ||
79 | struct rcu_torture { | |
80 | struct rcu_head rtort_rcu; | |
81 | int rtort_pipe_count; | |
82 | struct list_head rtort_free; | |
83 | }; | |
84 | ||
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) = | |
92 | { 0 }; | |
93 | static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) = | |
94 | { 0 }; | |
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 | ||
100 | /* | |
101 | * Allocate an element from the rcu_tortures pool. | |
102 | */ | |
103 | struct rcu_torture * | |
104 | rcu_torture_alloc(void) | |
105 | { | |
106 | struct list_head *p; | |
107 | ||
108 | spin_lock(&rcu_torture_lock); | |
109 | if (list_empty(&rcu_torture_freelist)) { | |
110 | atomic_inc(&n_rcu_torture_alloc_fail); | |
111 | spin_unlock(&rcu_torture_lock); | |
112 | return NULL; | |
113 | } | |
114 | atomic_inc(&n_rcu_torture_alloc); | |
115 | p = rcu_torture_freelist.next; | |
116 | list_del_init(p); | |
117 | spin_unlock(&rcu_torture_lock); | |
118 | return container_of(p, struct rcu_torture, rtort_free); | |
119 | } | |
120 | ||
121 | /* | |
122 | * Free an element to the rcu_tortures pool. | |
123 | */ | |
124 | static void | |
125 | rcu_torture_free(struct rcu_torture *p) | |
126 | { | |
127 | atomic_inc(&n_rcu_torture_free); | |
128 | spin_lock(&rcu_torture_lock); | |
129 | list_add_tail(&p->rtort_free, &rcu_torture_freelist); | |
130 | spin_unlock(&rcu_torture_lock); | |
131 | } | |
132 | ||
133 | static void | |
134 | rcu_torture_cb(struct rcu_head *p) | |
135 | { | |
136 | int i; | |
137 | struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu); | |
138 | ||
139 | if (fullstop) { | |
140 | /* Test is ending, just drop callbacks on the floor. */ | |
141 | /* The next initialization will pick up the pieces. */ | |
142 | return; | |
143 | } | |
144 | i = rp->rtort_pipe_count; | |
145 | if (i > RCU_TORTURE_PIPE_LEN) | |
146 | i = RCU_TORTURE_PIPE_LEN; | |
147 | atomic_inc(&rcu_torture_wcount[i]); | |
148 | if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) | |
149 | rcu_torture_free(rp); | |
150 | else | |
151 | call_rcu(p, rcu_torture_cb); | |
152 | } | |
153 | ||
154 | struct rcu_random_state { | |
155 | unsigned long rrs_state; | |
156 | unsigned long rrs_count; | |
157 | }; | |
158 | ||
159 | #define RCU_RANDOM_MULT 39916801 /* prime */ | |
160 | #define RCU_RANDOM_ADD 479001701 /* prime */ | |
161 | #define RCU_RANDOM_REFRESH 10000 | |
162 | ||
163 | #define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 } | |
164 | ||
165 | /* | |
166 | * Crude but fast random-number generator. Uses a linear congruential | |
167 | * generator, with occasional help from get_random_bytes(). | |
168 | */ | |
169 | static long | |
170 | rcu_random(struct rcu_random_state *rrsp) | |
171 | { | |
172 | long refresh; | |
173 | ||
174 | if (--rrsp->rrs_count < 0) { | |
175 | get_random_bytes(&refresh, sizeof(refresh)); | |
176 | rrsp->rrs_state += refresh; | |
177 | rrsp->rrs_count = RCU_RANDOM_REFRESH; | |
178 | } | |
179 | rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD; | |
180 | return swahw32(rrsp->rrs_state); | |
181 | } | |
182 | ||
183 | /* | |
184 | * RCU torture writer kthread. Repeatedly substitutes a new structure | |
185 | * for that pointed to by rcu_torture_current, freeing the old structure | |
186 | * after a series of grace periods (the "pipeline"). | |
187 | */ | |
188 | static int | |
189 | rcu_torture_writer(void *arg) | |
190 | { | |
191 | int i; | |
192 | long oldbatch = rcu_batches_completed(); | |
193 | struct rcu_torture *rp; | |
194 | struct rcu_torture *old_rp; | |
195 | static DEFINE_RCU_RANDOM(rand); | |
196 | ||
197 | VERBOSE_PRINTK_STRING("rcu_torture_writer task started"); | |
198 | do { | |
199 | schedule_timeout_uninterruptible(1); | |
200 | if (rcu_batches_completed() == oldbatch) | |
201 | continue; | |
202 | if ((rp = rcu_torture_alloc()) == NULL) | |
203 | continue; | |
204 | rp->rtort_pipe_count = 0; | |
205 | udelay(rcu_random(&rand) & 0x3ff); | |
206 | old_rp = rcu_torture_current; | |
207 | rcu_assign_pointer(rcu_torture_current, rp); | |
208 | smp_wmb(); | |
209 | if (old_rp != NULL) { | |
210 | i = old_rp->rtort_pipe_count; | |
211 | if (i > RCU_TORTURE_PIPE_LEN) | |
212 | i = RCU_TORTURE_PIPE_LEN; | |
213 | atomic_inc(&rcu_torture_wcount[i]); | |
214 | old_rp->rtort_pipe_count++; | |
215 | call_rcu(&old_rp->rtort_rcu, rcu_torture_cb); | |
216 | } | |
217 | rcu_torture_current_version++; | |
218 | oldbatch = rcu_batches_completed(); | |
219 | } while (!kthread_should_stop() && !fullstop); | |
220 | VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping"); | |
221 | while (!kthread_should_stop()) | |
222 | schedule_timeout_uninterruptible(1); | |
223 | return 0; | |
224 | } | |
225 | ||
226 | /* | |
227 | * RCU torture reader kthread. Repeatedly dereferences rcu_torture_current, | |
228 | * incrementing the corresponding element of the pipeline array. The | |
229 | * counter in the element should never be greater than 1, otherwise, the | |
230 | * RCU implementation is broken. | |
231 | */ | |
232 | static int | |
233 | rcu_torture_reader(void *arg) | |
234 | { | |
235 | int completed; | |
236 | DEFINE_RCU_RANDOM(rand); | |
237 | struct rcu_torture *p; | |
238 | int pipe_count; | |
239 | ||
240 | VERBOSE_PRINTK_STRING("rcu_torture_reader task started"); | |
241 | do { | |
242 | rcu_read_lock(); | |
243 | completed = rcu_batches_completed(); | |
244 | p = rcu_dereference(rcu_torture_current); | |
245 | if (p == NULL) { | |
246 | /* Wait for rcu_torture_writer to get underway */ | |
247 | rcu_read_unlock(); | |
248 | schedule_timeout_interruptible(HZ); | |
249 | continue; | |
250 | } | |
251 | udelay(rcu_random(&rand) & 0x7f); | |
252 | preempt_disable(); | |
253 | pipe_count = p->rtort_pipe_count; | |
254 | if (pipe_count > RCU_TORTURE_PIPE_LEN) { | |
255 | /* Should not happen, but... */ | |
256 | pipe_count = RCU_TORTURE_PIPE_LEN; | |
257 | } | |
258 | ++__get_cpu_var(rcu_torture_count)[pipe_count]; | |
259 | completed = rcu_batches_completed() - completed; | |
260 | if (completed > RCU_TORTURE_PIPE_LEN) { | |
261 | /* Should not happen, but... */ | |
262 | completed = RCU_TORTURE_PIPE_LEN; | |
263 | } | |
264 | ++__get_cpu_var(rcu_torture_batch)[completed]; | |
265 | preempt_enable(); | |
266 | rcu_read_unlock(); | |
267 | schedule(); | |
268 | } while (!kthread_should_stop() && !fullstop); | |
269 | VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping"); | |
270 | while (!kthread_should_stop()) | |
271 | schedule_timeout_uninterruptible(1); | |
272 | return 0; | |
273 | } | |
274 | ||
275 | /* | |
276 | * Create an RCU-torture statistics message in the specified buffer. | |
277 | */ | |
278 | static int | |
279 | rcu_torture_printk(char *page) | |
280 | { | |
281 | int cnt = 0; | |
282 | int cpu; | |
283 | int i; | |
284 | long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 }; | |
285 | long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 }; | |
286 | ||
287 | for_each_cpu(cpu) { | |
288 | for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) { | |
289 | pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i]; | |
290 | batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i]; | |
291 | } | |
292 | } | |
293 | for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) { | |
294 | if (pipesummary[i] != 0) | |
295 | break; | |
296 | } | |
297 | cnt += sprintf(&page[cnt], "rcutorture: "); | |
298 | cnt += sprintf(&page[cnt], | |
299 | "rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d", | |
300 | rcu_torture_current, | |
301 | rcu_torture_current_version, | |
302 | list_empty(&rcu_torture_freelist), | |
303 | atomic_read(&n_rcu_torture_alloc), | |
304 | atomic_read(&n_rcu_torture_alloc_fail), | |
305 | atomic_read(&n_rcu_torture_free)); | |
306 | cnt += sprintf(&page[cnt], "\nrcutorture: "); | |
307 | if (i > 1) | |
308 | cnt += sprintf(&page[cnt], "!!! "); | |
309 | cnt += sprintf(&page[cnt], "Reader Pipe: "); | |
310 | for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) | |
311 | cnt += sprintf(&page[cnt], " %ld", pipesummary[i]); | |
312 | cnt += sprintf(&page[cnt], "\nrcutorture: "); | |
313 | cnt += sprintf(&page[cnt], "Reader Batch: "); | |
314 | for (i = 0; i < RCU_TORTURE_PIPE_LEN; i++) | |
315 | cnt += sprintf(&page[cnt], " %ld", batchsummary[i]); | |
316 | cnt += sprintf(&page[cnt], "\nrcutorture: "); | |
317 | cnt += sprintf(&page[cnt], "Free-Block Circulation: "); | |
318 | for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) { | |
319 | cnt += sprintf(&page[cnt], " %d", | |
320 | atomic_read(&rcu_torture_wcount[i])); | |
321 | } | |
322 | cnt += sprintf(&page[cnt], "\n"); | |
323 | return cnt; | |
324 | } | |
325 | ||
326 | /* | |
327 | * Print torture statistics. Caller must ensure that there is only | |
328 | * one call to this function at a given time!!! This is normally | |
329 | * accomplished by relying on the module system to only have one copy | |
330 | * of the module loaded, and then by giving the rcu_torture_stats | |
331 | * kthread full control (or the init/cleanup functions when rcu_torture_stats | |
332 | * thread is not running). | |
333 | */ | |
334 | static void | |
335 | rcu_torture_stats_print(void) | |
336 | { | |
337 | int cnt; | |
338 | ||
339 | cnt = rcu_torture_printk(printk_buf); | |
340 | printk(KERN_ALERT "%s", printk_buf); | |
341 | } | |
342 | ||
343 | /* | |
344 | * Periodically prints torture statistics, if periodic statistics printing | |
345 | * was specified via the stat_interval module parameter. | |
346 | * | |
347 | * No need to worry about fullstop here, since this one doesn't reference | |
348 | * volatile state or register callbacks. | |
349 | */ | |
350 | static int | |
351 | rcu_torture_stats(void *arg) | |
352 | { | |
353 | VERBOSE_PRINTK_STRING("rcu_torture_stats task started"); | |
354 | do { | |
355 | schedule_timeout_interruptible(stat_interval * HZ); | |
356 | rcu_torture_stats_print(); | |
357 | } while (!kthread_should_stop()); | |
358 | VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping"); | |
359 | return 0; | |
360 | } | |
361 | ||
362 | static void | |
363 | rcu_torture_cleanup(void) | |
364 | { | |
365 | int i; | |
366 | ||
367 | fullstop = 1; | |
368 | if (writer_task != NULL) { | |
369 | VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task"); | |
370 | kthread_stop(writer_task); | |
371 | } | |
372 | writer_task = NULL; | |
373 | ||
374 | if (reader_tasks != NULL) { | |
375 | for (i = 0; i < nrealreaders; i++) { | |
376 | if (reader_tasks[i] != NULL) { | |
377 | VERBOSE_PRINTK_STRING( | |
378 | "Stopping rcu_torture_reader task"); | |
379 | kthread_stop(reader_tasks[i]); | |
380 | } | |
381 | reader_tasks[i] = NULL; | |
382 | } | |
383 | kfree(reader_tasks); | |
384 | reader_tasks = NULL; | |
385 | } | |
386 | rcu_torture_current = NULL; | |
387 | ||
388 | if (stats_task != NULL) { | |
389 | VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task"); | |
390 | kthread_stop(stats_task); | |
391 | } | |
392 | stats_task = NULL; | |
393 | ||
394 | /* Wait for all RCU callbacks to fire. */ | |
395 | ||
396 | for (i = 0; i < RCU_TORTURE_PIPE_LEN; i++) | |
397 | synchronize_rcu(); | |
398 | rcu_torture_stats_print(); /* -After- the stats thread is stopped! */ | |
399 | PRINTK_STRING("--- End of test"); | |
400 | } | |
401 | ||
402 | static int | |
403 | rcu_torture_init(void) | |
404 | { | |
405 | int i; | |
406 | int cpu; | |
407 | int firsterr = 0; | |
408 | ||
409 | /* Process args and tell the world that the torturer is on the job. */ | |
410 | ||
411 | if (nreaders >= 0) | |
412 | nrealreaders = nreaders; | |
413 | else | |
414 | nrealreaders = 2 * num_online_cpus(); | |
415 | printk(KERN_ALERT TORTURE_FLAG | |
416 | "--- Start of test: nreaders=%d stat_interval=%d verbose=%d\n", | |
417 | nrealreaders, stat_interval, verbose); | |
418 | fullstop = 0; | |
419 | ||
420 | /* Set up the freelist. */ | |
421 | ||
422 | INIT_LIST_HEAD(&rcu_torture_freelist); | |
423 | for (i = 0; i < sizeof(rcu_tortures) / sizeof(rcu_tortures[0]); i++) { | |
424 | list_add_tail(&rcu_tortures[i].rtort_free, | |
425 | &rcu_torture_freelist); | |
426 | } | |
427 | ||
428 | /* Initialize the statistics so that each run gets its own numbers. */ | |
429 | ||
430 | rcu_torture_current = NULL; | |
431 | rcu_torture_current_version = 0; | |
432 | atomic_set(&n_rcu_torture_alloc, 0); | |
433 | atomic_set(&n_rcu_torture_alloc_fail, 0); | |
434 | atomic_set(&n_rcu_torture_free, 0); | |
435 | for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) | |
436 | atomic_set(&rcu_torture_wcount[i], 0); | |
437 | for_each_cpu(cpu) { | |
438 | for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) { | |
439 | per_cpu(rcu_torture_count, cpu)[i] = 0; | |
440 | per_cpu(rcu_torture_batch, cpu)[i] = 0; | |
441 | } | |
442 | } | |
443 | ||
444 | /* Start up the kthreads. */ | |
445 | ||
446 | VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task"); | |
447 | writer_task = kthread_run(rcu_torture_writer, NULL, | |
448 | "rcu_torture_writer"); | |
449 | if (IS_ERR(writer_task)) { | |
450 | firsterr = PTR_ERR(writer_task); | |
451 | VERBOSE_PRINTK_ERRSTRING("Failed to create writer"); | |
452 | writer_task = NULL; | |
453 | goto unwind; | |
454 | } | |
455 | reader_tasks = kmalloc(nrealreaders * sizeof(reader_tasks[0]), | |
456 | GFP_KERNEL); | |
457 | if (reader_tasks == NULL) { | |
458 | VERBOSE_PRINTK_ERRSTRING("out of memory"); | |
459 | firsterr = -ENOMEM; | |
460 | goto unwind; | |
461 | } | |
462 | for (i = 0; i < nrealreaders; i++) { | |
463 | VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task"); | |
464 | reader_tasks[i] = kthread_run(rcu_torture_reader, NULL, | |
465 | "rcu_torture_reader"); | |
466 | if (IS_ERR(reader_tasks[i])) { | |
467 | firsterr = PTR_ERR(reader_tasks[i]); | |
468 | VERBOSE_PRINTK_ERRSTRING("Failed to create reader"); | |
469 | reader_tasks[i] = NULL; | |
470 | goto unwind; | |
471 | } | |
472 | } | |
473 | if (stat_interval > 0) { | |
474 | VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task"); | |
475 | stats_task = kthread_run(rcu_torture_stats, NULL, | |
476 | "rcu_torture_stats"); | |
477 | if (IS_ERR(stats_task)) { | |
478 | firsterr = PTR_ERR(stats_task); | |
479 | VERBOSE_PRINTK_ERRSTRING("Failed to create stats"); | |
480 | stats_task = NULL; | |
481 | goto unwind; | |
482 | } | |
483 | } | |
484 | return 0; | |
485 | ||
486 | unwind: | |
487 | rcu_torture_cleanup(); | |
488 | return firsterr; | |
489 | } | |
490 | ||
491 | module_init(rcu_torture_init); | |
492 | module_exit(rcu_torture_cleanup); |