1 // SPDX-License-Identifier: GPL-2.0+
2 //
3 // Torture test for smp_call_function() and friends.
4 //
5 // Copyright (C) Facebook, 2020.
6 //
7 // Author: Paul E. McKenney <paulmck@kernel.org>
8
9 #define pr_fmt(fmt) fmt
10
11 #include <linux/atomic.h>
12 #include <linux/bitops.h>
13 #include <linux/completion.h>
14 #include <linux/cpu.h>
15 #include <linux/delay.h>
16 #include <linux/err.h>
17 #include <linux/init.h>
18 #include <linux/interrupt.h>
19 #include <linux/kthread.h>
20 #include <linux/kernel.h>
21 #include <linux/mm.h>
22 #include <linux/module.h>
23 #include <linux/moduleparam.h>
24 #include <linux/notifier.h>
25 #include <linux/percpu.h>
26 #include <linux/rcupdate.h>
27 #include <linux/rcupdate_trace.h>
28 #include <linux/reboot.h>
29 #include <linux/sched.h>
30 #include <linux/spinlock.h>
31 #include <linux/smp.h>
32 #include <linux/stat.h>
33 #include <linux/srcu.h>
34 #include <linux/slab.h>
35 #include <linux/torture.h>
36 #include <linux/types.h>
37
38 #define SCFTORT_STRING "scftorture"
39 #define SCFTORT_FLAG SCFTORT_STRING ": "
40
41 #define SCFTORTOUT(s, x...) \
42 pr_alert(SCFTORT_FLAG s, ## x)
43
44 #define VERBOSE_SCFTORTOUT(s, x...) \
45 do { if (verbose) pr_alert(SCFTORT_FLAG s, ## x); } while (0)
46
47 #define VERBOSE_SCFTORTOUT_ERRSTRING(s, x...) \
48 do { if (verbose) pr_alert(SCFTORT_FLAG "!!! " s, ## x); } while (0)
49
50 MODULE_LICENSE("GPL");
51 MODULE_AUTHOR("Paul E. McKenney <paulmck@kernel.org>");
52
53 // Wait until there are multiple CPUs before starting test.
54 torture_param(int, holdoff, IS_BUILTIN(CONFIG_SCF_TORTURE_TEST) ? 10 : 0,
55 "Holdoff time before test start (s)");
56 torture_param(int, longwait, 0, "Include ridiculously long waits? (seconds)");
57 torture_param(int, nthreads, -1, "# threads, defaults to -1 for all CPUs.");
58 torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)");
59 torture_param(int, onoff_interval, 0, "Time between CPU hotplugs (s), 0=disable");
60 torture_param(int, shutdown_secs, 0, "Shutdown time (ms), <= zero to disable.");
61 torture_param(int, stat_interval, 60, "Number of seconds between stats printk()s.");
62 torture_param(int, stutter_cpus, 5, "Number of jiffies to change CPUs under test, 0=disable");
63 torture_param(bool, use_cpus_read_lock, 0, "Use cpus_read_lock() to exclude CPU hotplug.");
64 torture_param(int, verbose, 0, "Enable verbose debugging printk()s");
65 torture_param(int, weight_single, -1, "Testing weight for single-CPU no-wait operations.");
66 torture_param(int, weight_single_wait, -1, "Testing weight for single-CPU operations.");
67 torture_param(int, weight_many, -1, "Testing weight for multi-CPU no-wait operations.");
68 torture_param(int, weight_many_wait, -1, "Testing weight for multi-CPU operations.");
69 torture_param(int, weight_all, -1, "Testing weight for all-CPU no-wait operations.");
70 torture_param(int, weight_all_wait, -1, "Testing weight for all-CPU operations.");
71
72 char *torture_type = "";
73
74 #ifdef MODULE
75 # define SCFTORT_SHUTDOWN 0
76 #else
77 # define SCFTORT_SHUTDOWN 1
78 #endif
79
80 torture_param(bool, shutdown, SCFTORT_SHUTDOWN, "Shutdown at end of torture test.");
81
82 struct scf_statistics {
83 struct task_struct *task;
84 int cpu;
85 long long n_single;
86 long long n_single_ofl;
87 long long n_single_wait;
88 long long n_single_wait_ofl;
89 long long n_many;
90 long long n_many_wait;
91 long long n_all;
92 long long n_all_wait;
93 };
94
95 static struct scf_statistics *scf_stats_p;
96 static struct task_struct *scf_torture_stats_task;
97 static DEFINE_PER_CPU(long long, scf_invoked_count);
98
99 // Data for random primitive selection
100 #define SCF_PRIM_SINGLE 0
101 #define SCF_PRIM_MANY 1
102 #define SCF_PRIM_ALL 2
103 #define SCF_NPRIMS (2 * 3) // Need wait and no-wait versions of each.
104
105 static char *scf_prim_name[] = {
106 "smp_call_function_single",
107 "smp_call_function_many",
108 "smp_call_function",
109 };
110
111 struct scf_selector {
112 unsigned long scfs_weight;
113 int scfs_prim;
114 bool scfs_wait;
115 };
116 static struct scf_selector scf_sel_array[SCF_NPRIMS];
117 static int scf_sel_array_len;
118 static unsigned long scf_sel_totweight;
119
120 // Communicate between caller and handler.
121 struct scf_check {
122 bool scfc_in;
123 bool scfc_out;
124 int scfc_cpu; // -1 for not _single().
125 bool scfc_wait;
126 };
127
128 // Use to wait for all threads to start.
129 static atomic_t n_started;
130 static atomic_t n_errs;
131 static atomic_t n_mb_in_errs;
132 static atomic_t n_mb_out_errs;
133 static atomic_t n_alloc_errs;
134 static bool scfdone;
135 static char *bangstr = "";
136
137 static DEFINE_TORTURE_RANDOM_PERCPU(scf_torture_rand);
138
139 // Print torture statistics. Caller must ensure serialization.
scf_torture_stats_print(void)140 static void scf_torture_stats_print(void)
141 {
142 int cpu;
143 int i;
144 long long invoked_count = 0;
145 bool isdone = READ_ONCE(scfdone);
146 struct scf_statistics scfs = {};
147
148 for_each_possible_cpu(cpu)
149 invoked_count += data_race(per_cpu(scf_invoked_count, cpu));
150 for (i = 0; i < nthreads; i++) {
151 scfs.n_single += scf_stats_p[i].n_single;
152 scfs.n_single_ofl += scf_stats_p[i].n_single_ofl;
153 scfs.n_single_wait += scf_stats_p[i].n_single_wait;
154 scfs.n_single_wait_ofl += scf_stats_p[i].n_single_wait_ofl;
155 scfs.n_many += scf_stats_p[i].n_many;
156 scfs.n_many_wait += scf_stats_p[i].n_many_wait;
157 scfs.n_all += scf_stats_p[i].n_all;
158 scfs.n_all_wait += scf_stats_p[i].n_all_wait;
159 }
160 if (atomic_read(&n_errs) || atomic_read(&n_mb_in_errs) ||
161 atomic_read(&n_mb_out_errs) || atomic_read(&n_alloc_errs))
162 bangstr = "!!! ";
163 pr_alert("%s %sscf_invoked_count %s: %lld single: %lld/%lld single_ofl: %lld/%lld many: %lld/%lld all: %lld/%lld ",
164 SCFTORT_FLAG, bangstr, isdone ? "VER" : "ver", invoked_count,
165 scfs.n_single, scfs.n_single_wait, scfs.n_single_ofl, scfs.n_single_wait_ofl,
166 scfs.n_many, scfs.n_many_wait, scfs.n_all, scfs.n_all_wait);
167 torture_onoff_stats();
168 pr_cont("ste: %d stnmie: %d stnmoe: %d staf: %d\n", atomic_read(&n_errs),
169 atomic_read(&n_mb_in_errs), atomic_read(&n_mb_out_errs),
170 atomic_read(&n_alloc_errs));
171 }
172
173 // Periodically prints torture statistics, if periodic statistics printing
174 // was specified via the stat_interval module parameter.
175 static int
scf_torture_stats(void * arg)176 scf_torture_stats(void *arg)
177 {
178 VERBOSE_TOROUT_STRING("scf_torture_stats task started");
179 do {
180 schedule_timeout_interruptible(stat_interval * HZ);
181 scf_torture_stats_print();
182 torture_shutdown_absorb("scf_torture_stats");
183 } while (!torture_must_stop());
184 torture_kthread_stopping("scf_torture_stats");
185 return 0;
186 }
187
188 // Add a primitive to the scf_sel_array[].
scf_sel_add(unsigned long weight,int prim,bool wait)189 static void scf_sel_add(unsigned long weight, int prim, bool wait)
190 {
191 struct scf_selector *scfsp = &scf_sel_array[scf_sel_array_len];
192
193 // If no weight, if array would overflow, if computing three-place
194 // percentages would overflow, or if the scf_prim_name[] array would
195 // overflow, don't bother. In the last three two cases, complain.
196 if (!weight ||
197 WARN_ON_ONCE(scf_sel_array_len >= ARRAY_SIZE(scf_sel_array)) ||
198 WARN_ON_ONCE(0 - 100000 * weight <= 100000 * scf_sel_totweight) ||
199 WARN_ON_ONCE(prim >= ARRAY_SIZE(scf_prim_name)))
200 return;
201 scf_sel_totweight += weight;
202 scfsp->scfs_weight = scf_sel_totweight;
203 scfsp->scfs_prim = prim;
204 scfsp->scfs_wait = wait;
205 scf_sel_array_len++;
206 }
207
208 // Dump out weighting percentages for scf_prim_name[] array.
scf_sel_dump(void)209 static void scf_sel_dump(void)
210 {
211 int i;
212 unsigned long oldw = 0;
213 struct scf_selector *scfsp;
214 unsigned long w;
215
216 for (i = 0; i < scf_sel_array_len; i++) {
217 scfsp = &scf_sel_array[i];
218 w = (scfsp->scfs_weight - oldw) * 100000 / scf_sel_totweight;
219 pr_info("%s: %3lu.%03lu %s(%s)\n", __func__, w / 1000, w % 1000,
220 scf_prim_name[scfsp->scfs_prim],
221 scfsp->scfs_wait ? "wait" : "nowait");
222 oldw = scfsp->scfs_weight;
223 }
224 }
225
226 // Randomly pick a primitive and wait/nowait, based on weightings.
scf_sel_rand(struct torture_random_state * trsp)227 static struct scf_selector *scf_sel_rand(struct torture_random_state *trsp)
228 {
229 int i;
230 unsigned long w = torture_random(trsp) % (scf_sel_totweight + 1);
231
232 for (i = 0; i < scf_sel_array_len; i++)
233 if (scf_sel_array[i].scfs_weight >= w)
234 return &scf_sel_array[i];
235 WARN_ON_ONCE(1);
236 return &scf_sel_array[0];
237 }
238
239 // Update statistics and occasionally burn up mass quantities of CPU time,
240 // if told to do so via scftorture.longwait. Otherwise, occasionally burn
241 // a little bit.
scf_handler(void * scfc_in)242 static void scf_handler(void *scfc_in)
243 {
244 int i;
245 int j;
246 unsigned long r = torture_random(this_cpu_ptr(&scf_torture_rand));
247 struct scf_check *scfcp = scfc_in;
248
249 if (likely(scfcp)) {
250 WRITE_ONCE(scfcp->scfc_out, false); // For multiple receivers.
251 if (WARN_ON_ONCE(unlikely(!READ_ONCE(scfcp->scfc_in))))
252 atomic_inc(&n_mb_in_errs);
253 }
254 this_cpu_inc(scf_invoked_count);
255 if (longwait <= 0) {
256 if (!(r & 0xffc0)) {
257 udelay(r & 0x3f);
258 goto out;
259 }
260 }
261 if (r & 0xfff)
262 goto out;
263 r = (r >> 12);
264 if (longwait <= 0) {
265 udelay((r & 0xff) + 1);
266 goto out;
267 }
268 r = r % longwait + 1;
269 for (i = 0; i < r; i++) {
270 for (j = 0; j < 1000; j++) {
271 udelay(1000);
272 cpu_relax();
273 }
274 }
275 out:
276 if (unlikely(!scfcp))
277 return;
278 if (scfcp->scfc_wait)
279 WRITE_ONCE(scfcp->scfc_out, true);
280 else
281 kfree(scfcp);
282 }
283
284 // As above, but check for correct CPU.
scf_handler_1(void * scfc_in)285 static void scf_handler_1(void *scfc_in)
286 {
287 struct scf_check *scfcp = scfc_in;
288
289 if (likely(scfcp) && WARN_ONCE(smp_processor_id() != scfcp->scfc_cpu, "%s: Wanted CPU %d got CPU %d\n", __func__, scfcp->scfc_cpu, smp_processor_id())) {
290 atomic_inc(&n_errs);
291 }
292 scf_handler(scfcp);
293 }
294
295 // Randomly do an smp_call_function*() invocation.
scftorture_invoke_one(struct scf_statistics * scfp,struct torture_random_state * trsp)296 static void scftorture_invoke_one(struct scf_statistics *scfp, struct torture_random_state *trsp)
297 {
298 uintptr_t cpu;
299 int ret = 0;
300 struct scf_check *scfcp = NULL;
301 struct scf_selector *scfsp = scf_sel_rand(trsp);
302
303 if (use_cpus_read_lock)
304 cpus_read_lock();
305 else
306 preempt_disable();
307 if (scfsp->scfs_prim == SCF_PRIM_SINGLE || scfsp->scfs_wait) {
308 scfcp = kmalloc(sizeof(*scfcp), GFP_ATOMIC);
309 if (WARN_ON_ONCE(!scfcp)) {
310 atomic_inc(&n_alloc_errs);
311 } else {
312 scfcp->scfc_cpu = -1;
313 scfcp->scfc_wait = scfsp->scfs_wait;
314 scfcp->scfc_out = false;
315 }
316 }
317 switch (scfsp->scfs_prim) {
318 case SCF_PRIM_SINGLE:
319 cpu = torture_random(trsp) % nr_cpu_ids;
320 if (scfsp->scfs_wait)
321 scfp->n_single_wait++;
322 else
323 scfp->n_single++;
324 if (scfcp) {
325 scfcp->scfc_cpu = cpu;
326 barrier(); // Prevent race-reduction compiler optimizations.
327 scfcp->scfc_in = true;
328 }
329 ret = smp_call_function_single(cpu, scf_handler_1, (void *)scfcp, scfsp->scfs_wait);
330 if (ret) {
331 if (scfsp->scfs_wait)
332 scfp->n_single_wait_ofl++;
333 else
334 scfp->n_single_ofl++;
335 kfree(scfcp);
336 scfcp = NULL;
337 }
338 break;
339 case SCF_PRIM_MANY:
340 if (scfsp->scfs_wait)
341 scfp->n_many_wait++;
342 else
343 scfp->n_many++;
344 if (scfcp) {
345 barrier(); // Prevent race-reduction compiler optimizations.
346 scfcp->scfc_in = true;
347 }
348 smp_call_function_many(cpu_online_mask, scf_handler, scfcp, scfsp->scfs_wait);
349 break;
350 case SCF_PRIM_ALL:
351 if (scfsp->scfs_wait)
352 scfp->n_all_wait++;
353 else
354 scfp->n_all++;
355 if (scfcp) {
356 barrier(); // Prevent race-reduction compiler optimizations.
357 scfcp->scfc_in = true;
358 }
359 smp_call_function(scf_handler, scfcp, scfsp->scfs_wait);
360 break;
361 default:
362 WARN_ON_ONCE(1);
363 if (scfcp)
364 scfcp->scfc_out = true;
365 }
366 if (scfcp && scfsp->scfs_wait) {
367 if (WARN_ON_ONCE((num_online_cpus() > 1 || scfsp->scfs_prim == SCF_PRIM_SINGLE) &&
368 !scfcp->scfc_out))
369 atomic_inc(&n_mb_out_errs); // Leak rather than trash!
370 else
371 kfree(scfcp);
372 barrier(); // Prevent race-reduction compiler optimizations.
373 }
374 if (use_cpus_read_lock)
375 cpus_read_unlock();
376 else
377 preempt_enable();
378 if (!(torture_random(trsp) & 0xfff))
379 schedule_timeout_uninterruptible(1);
380 }
381
382 // SCF test kthread. Repeatedly does calls to members of the
383 // smp_call_function() family of functions.
scftorture_invoker(void * arg)384 static int scftorture_invoker(void *arg)
385 {
386 int cpu;
387 DEFINE_TORTURE_RANDOM(rand);
388 struct scf_statistics *scfp = (struct scf_statistics *)arg;
389 bool was_offline = false;
390
391 VERBOSE_SCFTORTOUT("scftorture_invoker %d: task started", scfp->cpu);
392 cpu = scfp->cpu % nr_cpu_ids;
393 set_cpus_allowed_ptr(current, cpumask_of(cpu));
394 set_user_nice(current, MAX_NICE);
395 if (holdoff)
396 schedule_timeout_interruptible(holdoff * HZ);
397
398 VERBOSE_SCFTORTOUT("scftorture_invoker %d: Waiting for all SCF torturers from cpu %d", scfp->cpu, smp_processor_id());
399
400 // Make sure that the CPU is affinitized appropriately during testing.
401 WARN_ON_ONCE(smp_processor_id() != scfp->cpu);
402
403 if (!atomic_dec_return(&n_started))
404 while (atomic_read_acquire(&n_started)) {
405 if (torture_must_stop()) {
406 VERBOSE_SCFTORTOUT("scftorture_invoker %d ended before starting", scfp->cpu);
407 goto end;
408 }
409 schedule_timeout_uninterruptible(1);
410 }
411
412 VERBOSE_SCFTORTOUT("scftorture_invoker %d started", scfp->cpu);
413
414 do {
415 scftorture_invoke_one(scfp, &rand);
416 while (cpu_is_offline(cpu) && !torture_must_stop()) {
417 schedule_timeout_interruptible(HZ / 5);
418 was_offline = true;
419 }
420 if (was_offline) {
421 set_cpus_allowed_ptr(current, cpumask_of(cpu));
422 was_offline = false;
423 }
424 cond_resched();
425 } while (!torture_must_stop());
426
427 VERBOSE_SCFTORTOUT("scftorture_invoker %d ended", scfp->cpu);
428 end:
429 torture_kthread_stopping("scftorture_invoker");
430 return 0;
431 }
432
433 static void
scftorture_print_module_parms(const char * tag)434 scftorture_print_module_parms(const char *tag)
435 {
436 pr_alert(SCFTORT_FLAG
437 "--- %s: verbose=%d holdoff=%d longwait=%d nthreads=%d onoff_holdoff=%d onoff_interval=%d shutdown_secs=%d stat_interval=%d stutter_cpus=%d use_cpus_read_lock=%d, weight_single=%d, weight_single_wait=%d, weight_many=%d, weight_many_wait=%d, weight_all=%d, weight_all_wait=%d\n", tag,
438 verbose, holdoff, longwait, nthreads, onoff_holdoff, onoff_interval, shutdown, stat_interval, stutter_cpus, use_cpus_read_lock, weight_single, weight_single_wait, weight_many, weight_many_wait, weight_all, weight_all_wait);
439 }
440
scf_cleanup_handler(void * unused)441 static void scf_cleanup_handler(void *unused)
442 {
443 }
444
scf_torture_cleanup(void)445 static void scf_torture_cleanup(void)
446 {
447 int i;
448
449 if (torture_cleanup_begin())
450 return;
451
452 WRITE_ONCE(scfdone, true);
453 if (nthreads)
454 for (i = 0; i < nthreads; i++)
455 torture_stop_kthread("scftorture_invoker", scf_stats_p[i].task);
456 else
457 goto end;
458 smp_call_function(scf_cleanup_handler, NULL, 0);
459 torture_stop_kthread(scf_torture_stats, scf_torture_stats_task);
460 scf_torture_stats_print(); // -After- the stats thread is stopped!
461 kfree(scf_stats_p); // -After- the last stats print has completed!
462 scf_stats_p = NULL;
463
464 if (atomic_read(&n_errs) || atomic_read(&n_mb_in_errs) || atomic_read(&n_mb_out_errs))
465 scftorture_print_module_parms("End of test: FAILURE");
466 else if (torture_onoff_failures())
467 scftorture_print_module_parms("End of test: LOCK_HOTPLUG");
468 else
469 scftorture_print_module_parms("End of test: SUCCESS");
470
471 end:
472 torture_cleanup_end();
473 }
474
scf_torture_init(void)475 static int __init scf_torture_init(void)
476 {
477 long i;
478 int firsterr = 0;
479 unsigned long weight_single1 = weight_single;
480 unsigned long weight_single_wait1 = weight_single_wait;
481 unsigned long weight_many1 = weight_many;
482 unsigned long weight_many_wait1 = weight_many_wait;
483 unsigned long weight_all1 = weight_all;
484 unsigned long weight_all_wait1 = weight_all_wait;
485
486 if (!torture_init_begin(SCFTORT_STRING, verbose))
487 return -EBUSY;
488
489 scftorture_print_module_parms("Start of test");
490
491 if (weight_single == -1 && weight_single_wait == -1 &&
492 weight_many == -1 && weight_many_wait == -1 &&
493 weight_all == -1 && weight_all_wait == -1) {
494 weight_single1 = 2 * nr_cpu_ids;
495 weight_single_wait1 = 2 * nr_cpu_ids;
496 weight_many1 = 2;
497 weight_many_wait1 = 2;
498 weight_all1 = 1;
499 weight_all_wait1 = 1;
500 } else {
501 if (weight_single == -1)
502 weight_single1 = 0;
503 if (weight_single_wait == -1)
504 weight_single_wait1 = 0;
505 if (weight_many == -1)
506 weight_many1 = 0;
507 if (weight_many_wait == -1)
508 weight_many_wait1 = 0;
509 if (weight_all == -1)
510 weight_all1 = 0;
511 if (weight_all_wait == -1)
512 weight_all_wait1 = 0;
513 }
514 if (weight_single1 == 0 && weight_single_wait1 == 0 &&
515 weight_many1 == 0 && weight_many_wait1 == 0 &&
516 weight_all1 == 0 && weight_all_wait1 == 0) {
517 VERBOSE_SCFTORTOUT_ERRSTRING("all zero weights makes no sense");
518 firsterr = -EINVAL;
519 goto unwind;
520 }
521 scf_sel_add(weight_single1, SCF_PRIM_SINGLE, false);
522 scf_sel_add(weight_single_wait1, SCF_PRIM_SINGLE, true);
523 scf_sel_add(weight_many1, SCF_PRIM_MANY, false);
524 scf_sel_add(weight_many_wait1, SCF_PRIM_MANY, true);
525 scf_sel_add(weight_all1, SCF_PRIM_ALL, false);
526 scf_sel_add(weight_all_wait1, SCF_PRIM_ALL, true);
527 scf_sel_dump();
528
529 if (onoff_interval > 0) {
530 firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval, NULL);
531 if (firsterr)
532 goto unwind;
533 }
534 if (shutdown_secs > 0) {
535 firsterr = torture_shutdown_init(shutdown_secs, scf_torture_cleanup);
536 if (firsterr)
537 goto unwind;
538 }
539
540 // Worker tasks invoking smp_call_function().
541 if (nthreads < 0)
542 nthreads = num_online_cpus();
543 scf_stats_p = kcalloc(nthreads, sizeof(scf_stats_p[0]), GFP_KERNEL);
544 if (!scf_stats_p) {
545 VERBOSE_SCFTORTOUT_ERRSTRING("out of memory");
546 firsterr = -ENOMEM;
547 goto unwind;
548 }
549
550 VERBOSE_SCFTORTOUT("Starting %d smp_call_function() threads\n", nthreads);
551
552 atomic_set(&n_started, nthreads);
553 for (i = 0; i < nthreads; i++) {
554 scf_stats_p[i].cpu = i;
555 firsterr = torture_create_kthread(scftorture_invoker, (void *)&scf_stats_p[i],
556 scf_stats_p[i].task);
557 if (firsterr)
558 goto unwind;
559 }
560 if (stat_interval > 0) {
561 firsterr = torture_create_kthread(scf_torture_stats, NULL, scf_torture_stats_task);
562 if (firsterr)
563 goto unwind;
564 }
565
566 torture_init_end();
567 return 0;
568
569 unwind:
570 torture_init_end();
571 scf_torture_cleanup();
572 return firsterr;
573 }
574
575 module_init(scf_torture_init);
576 module_exit(scf_torture_cleanup);
577