Merge tag 'for-5.16/block-2021-11-09' of git://git.kernel.dk/linux-block
[linux-2.6-microblaze.git] / kernel / scftorture.c
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, 5, "Number of jiffies to run/halt 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_resched, -1, "Testing weight for resched_cpu() operations.");
66 torture_param(int, weight_single, -1, "Testing weight for single-CPU no-wait operations.");
67 torture_param(int, weight_single_rpc, -1, "Testing weight for single-CPU RPC operations.");
68 torture_param(int, weight_single_wait, -1, "Testing weight for single-CPU operations.");
69 torture_param(int, weight_many, -1, "Testing weight for multi-CPU no-wait operations.");
70 torture_param(int, weight_many_wait, -1, "Testing weight for multi-CPU operations.");
71 torture_param(int, weight_all, -1, "Testing weight for all-CPU no-wait operations.");
72 torture_param(int, weight_all_wait, -1, "Testing weight for all-CPU operations.");
73
74 char *torture_type = "";
75
76 #ifdef MODULE
77 # define SCFTORT_SHUTDOWN 0
78 #else
79 # define SCFTORT_SHUTDOWN 1
80 #endif
81
82 torture_param(bool, shutdown, SCFTORT_SHUTDOWN, "Shutdown at end of torture test.");
83
84 struct scf_statistics {
85         struct task_struct *task;
86         int cpu;
87         long long n_resched;
88         long long n_single;
89         long long n_single_ofl;
90         long long n_single_rpc;
91         long long n_single_rpc_ofl;
92         long long n_single_wait;
93         long long n_single_wait_ofl;
94         long long n_many;
95         long long n_many_wait;
96         long long n_all;
97         long long n_all_wait;
98 };
99
100 static struct scf_statistics *scf_stats_p;
101 static struct task_struct *scf_torture_stats_task;
102 static DEFINE_PER_CPU(long long, scf_invoked_count);
103
104 // Data for random primitive selection
105 #define SCF_PRIM_RESCHED        0
106 #define SCF_PRIM_SINGLE         1
107 #define SCF_PRIM_SINGLE_RPC     2
108 #define SCF_PRIM_MANY           3
109 #define SCF_PRIM_ALL            4
110 #define SCF_NPRIMS              8 // Need wait and no-wait versions of each,
111                                   //  except for SCF_PRIM_RESCHED and
112                                   //  SCF_PRIM_SINGLE_RPC.
113
114 static char *scf_prim_name[] = {
115         "resched_cpu",
116         "smp_call_function_single",
117         "smp_call_function_single_rpc",
118         "smp_call_function_many",
119         "smp_call_function",
120 };
121
122 struct scf_selector {
123         unsigned long scfs_weight;
124         int scfs_prim;
125         bool scfs_wait;
126 };
127 static struct scf_selector scf_sel_array[SCF_NPRIMS];
128 static int scf_sel_array_len;
129 static unsigned long scf_sel_totweight;
130
131 // Communicate between caller and handler.
132 struct scf_check {
133         bool scfc_in;
134         bool scfc_out;
135         int scfc_cpu; // -1 for not _single().
136         bool scfc_wait;
137         bool scfc_rpc;
138         struct completion scfc_completion;
139 };
140
141 // Use to wait for all threads to start.
142 static atomic_t n_started;
143 static atomic_t n_errs;
144 static atomic_t n_mb_in_errs;
145 static atomic_t n_mb_out_errs;
146 static atomic_t n_alloc_errs;
147 static bool scfdone;
148 static char *bangstr = "";
149
150 static DEFINE_TORTURE_RANDOM_PERCPU(scf_torture_rand);
151
152 extern void resched_cpu(int cpu); // An alternative IPI vector.
153
154 // Print torture statistics.  Caller must ensure serialization.
155 static void scf_torture_stats_print(void)
156 {
157         int cpu;
158         int i;
159         long long invoked_count = 0;
160         bool isdone = READ_ONCE(scfdone);
161         struct scf_statistics scfs = {};
162
163         for_each_possible_cpu(cpu)
164                 invoked_count += data_race(per_cpu(scf_invoked_count, cpu));
165         for (i = 0; i < nthreads; i++) {
166                 scfs.n_resched += scf_stats_p[i].n_resched;
167                 scfs.n_single += scf_stats_p[i].n_single;
168                 scfs.n_single_ofl += scf_stats_p[i].n_single_ofl;
169                 scfs.n_single_rpc += scf_stats_p[i].n_single_rpc;
170                 scfs.n_single_wait += scf_stats_p[i].n_single_wait;
171                 scfs.n_single_wait_ofl += scf_stats_p[i].n_single_wait_ofl;
172                 scfs.n_many += scf_stats_p[i].n_many;
173                 scfs.n_many_wait += scf_stats_p[i].n_many_wait;
174                 scfs.n_all += scf_stats_p[i].n_all;
175                 scfs.n_all_wait += scf_stats_p[i].n_all_wait;
176         }
177         if (atomic_read(&n_errs) || atomic_read(&n_mb_in_errs) ||
178             atomic_read(&n_mb_out_errs) || atomic_read(&n_alloc_errs))
179                 bangstr = "!!! ";
180         pr_alert("%s %sscf_invoked_count %s: %lld resched: %lld single: %lld/%lld single_ofl: %lld/%lld single_rpc: %lld single_rpc_ofl: %lld many: %lld/%lld all: %lld/%lld ",
181                  SCFTORT_FLAG, bangstr, isdone ? "VER" : "ver", invoked_count, scfs.n_resched,
182                  scfs.n_single, scfs.n_single_wait, scfs.n_single_ofl, scfs.n_single_wait_ofl,
183                  scfs.n_single_rpc, scfs.n_single_rpc_ofl,
184                  scfs.n_many, scfs.n_many_wait, scfs.n_all, scfs.n_all_wait);
185         torture_onoff_stats();
186         pr_cont("ste: %d stnmie: %d stnmoe: %d staf: %d\n", atomic_read(&n_errs),
187                 atomic_read(&n_mb_in_errs), atomic_read(&n_mb_out_errs),
188                 atomic_read(&n_alloc_errs));
189 }
190
191 // Periodically prints torture statistics, if periodic statistics printing
192 // was specified via the stat_interval module parameter.
193 static int
194 scf_torture_stats(void *arg)
195 {
196         VERBOSE_TOROUT_STRING("scf_torture_stats task started");
197         do {
198                 schedule_timeout_interruptible(stat_interval * HZ);
199                 scf_torture_stats_print();
200                 torture_shutdown_absorb("scf_torture_stats");
201         } while (!torture_must_stop());
202         torture_kthread_stopping("scf_torture_stats");
203         return 0;
204 }
205
206 // Add a primitive to the scf_sel_array[].
207 static void scf_sel_add(unsigned long weight, int prim, bool wait)
208 {
209         struct scf_selector *scfsp = &scf_sel_array[scf_sel_array_len];
210
211         // If no weight, if array would overflow, if computing three-place
212         // percentages would overflow, or if the scf_prim_name[] array would
213         // overflow, don't bother.  In the last three two cases, complain.
214         if (!weight ||
215             WARN_ON_ONCE(scf_sel_array_len >= ARRAY_SIZE(scf_sel_array)) ||
216             WARN_ON_ONCE(0 - 100000 * weight <= 100000 * scf_sel_totweight) ||
217             WARN_ON_ONCE(prim >= ARRAY_SIZE(scf_prim_name)))
218                 return;
219         scf_sel_totweight += weight;
220         scfsp->scfs_weight = scf_sel_totweight;
221         scfsp->scfs_prim = prim;
222         scfsp->scfs_wait = wait;
223         scf_sel_array_len++;
224 }
225
226 // Dump out weighting percentages for scf_prim_name[] array.
227 static void scf_sel_dump(void)
228 {
229         int i;
230         unsigned long oldw = 0;
231         struct scf_selector *scfsp;
232         unsigned long w;
233
234         for (i = 0; i < scf_sel_array_len; i++) {
235                 scfsp = &scf_sel_array[i];
236                 w = (scfsp->scfs_weight - oldw) * 100000 / scf_sel_totweight;
237                 pr_info("%s: %3lu.%03lu %s(%s)\n", __func__, w / 1000, w % 1000,
238                         scf_prim_name[scfsp->scfs_prim],
239                         scfsp->scfs_wait ? "wait" : "nowait");
240                 oldw = scfsp->scfs_weight;
241         }
242 }
243
244 // Randomly pick a primitive and wait/nowait, based on weightings.
245 static struct scf_selector *scf_sel_rand(struct torture_random_state *trsp)
246 {
247         int i;
248         unsigned long w = torture_random(trsp) % (scf_sel_totweight + 1);
249
250         for (i = 0; i < scf_sel_array_len; i++)
251                 if (scf_sel_array[i].scfs_weight >= w)
252                         return &scf_sel_array[i];
253         WARN_ON_ONCE(1);
254         return &scf_sel_array[0];
255 }
256
257 // Update statistics and occasionally burn up mass quantities of CPU time,
258 // if told to do so via scftorture.longwait.  Otherwise, occasionally burn
259 // a little bit.
260 static void scf_handler(void *scfc_in)
261 {
262         int i;
263         int j;
264         unsigned long r = torture_random(this_cpu_ptr(&scf_torture_rand));
265         struct scf_check *scfcp = scfc_in;
266
267         if (likely(scfcp)) {
268                 WRITE_ONCE(scfcp->scfc_out, false); // For multiple receivers.
269                 if (WARN_ON_ONCE(unlikely(!READ_ONCE(scfcp->scfc_in))))
270                         atomic_inc(&n_mb_in_errs);
271         }
272         this_cpu_inc(scf_invoked_count);
273         if (longwait <= 0) {
274                 if (!(r & 0xffc0))
275                         udelay(r & 0x3f);
276                 goto out;
277         }
278         if (r & 0xfff)
279                 goto out;
280         r = (r >> 12);
281         if (longwait <= 0) {
282                 udelay((r & 0xff) + 1);
283                 goto out;
284         }
285         r = r % longwait + 1;
286         for (i = 0; i < r; i++) {
287                 for (j = 0; j < 1000; j++) {
288                         udelay(1000);
289                         cpu_relax();
290                 }
291         }
292 out:
293         if (unlikely(!scfcp))
294                 return;
295         if (scfcp->scfc_wait) {
296                 WRITE_ONCE(scfcp->scfc_out, true);
297                 if (scfcp->scfc_rpc)
298                         complete(&scfcp->scfc_completion);
299         } else {
300                 kfree(scfcp);
301         }
302 }
303
304 // As above, but check for correct CPU.
305 static void scf_handler_1(void *scfc_in)
306 {
307         struct scf_check *scfcp = scfc_in;
308
309         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())) {
310                 atomic_inc(&n_errs);
311         }
312         scf_handler(scfcp);
313 }
314
315 // Randomly do an smp_call_function*() invocation.
316 static void scftorture_invoke_one(struct scf_statistics *scfp, struct torture_random_state *trsp)
317 {
318         uintptr_t cpu;
319         int ret = 0;
320         struct scf_check *scfcp = NULL;
321         struct scf_selector *scfsp = scf_sel_rand(trsp);
322
323         if (use_cpus_read_lock)
324                 cpus_read_lock();
325         else
326                 preempt_disable();
327         if (scfsp->scfs_prim == SCF_PRIM_SINGLE || scfsp->scfs_wait) {
328                 scfcp = kmalloc(sizeof(*scfcp), GFP_ATOMIC);
329                 if (WARN_ON_ONCE(!scfcp)) {
330                         atomic_inc(&n_alloc_errs);
331                 } else {
332                         scfcp->scfc_cpu = -1;
333                         scfcp->scfc_wait = scfsp->scfs_wait;
334                         scfcp->scfc_out = false;
335                         scfcp->scfc_rpc = false;
336                 }
337         }
338         switch (scfsp->scfs_prim) {
339         case SCF_PRIM_RESCHED:
340                 if (IS_BUILTIN(CONFIG_SCF_TORTURE_TEST)) {
341                         cpu = torture_random(trsp) % nr_cpu_ids;
342                         scfp->n_resched++;
343                         resched_cpu(cpu);
344                         this_cpu_inc(scf_invoked_count);
345                 }
346                 break;
347         case SCF_PRIM_SINGLE:
348                 cpu = torture_random(trsp) % nr_cpu_ids;
349                 if (scfsp->scfs_wait)
350                         scfp->n_single_wait++;
351                 else
352                         scfp->n_single++;
353                 if (scfcp) {
354                         scfcp->scfc_cpu = cpu;
355                         barrier(); // Prevent race-reduction compiler optimizations.
356                         scfcp->scfc_in = true;
357                 }
358                 ret = smp_call_function_single(cpu, scf_handler_1, (void *)scfcp, scfsp->scfs_wait);
359                 if (ret) {
360                         if (scfsp->scfs_wait)
361                                 scfp->n_single_wait_ofl++;
362                         else
363                                 scfp->n_single_ofl++;
364                         kfree(scfcp);
365                         scfcp = NULL;
366                 }
367                 break;
368         case SCF_PRIM_SINGLE_RPC:
369                 if (!scfcp)
370                         break;
371                 cpu = torture_random(trsp) % nr_cpu_ids;
372                 scfp->n_single_rpc++;
373                 scfcp->scfc_cpu = cpu;
374                 scfcp->scfc_wait = true;
375                 init_completion(&scfcp->scfc_completion);
376                 scfcp->scfc_rpc = true;
377                 barrier(); // Prevent race-reduction compiler optimizations.
378                 scfcp->scfc_in = true;
379                 ret = smp_call_function_single(cpu, scf_handler_1, (void *)scfcp, 0);
380                 if (!ret) {
381                         if (use_cpus_read_lock)
382                                 cpus_read_unlock();
383                         else
384                                 preempt_enable();
385                         wait_for_completion(&scfcp->scfc_completion);
386                         if (use_cpus_read_lock)
387                                 cpus_read_lock();
388                         else
389                                 preempt_disable();
390                 } else {
391                         scfp->n_single_rpc_ofl++;
392                         kfree(scfcp);
393                         scfcp = NULL;
394                 }
395                 break;
396         case SCF_PRIM_MANY:
397                 if (scfsp->scfs_wait)
398                         scfp->n_many_wait++;
399                 else
400                         scfp->n_many++;
401                 if (scfcp) {
402                         barrier(); // Prevent race-reduction compiler optimizations.
403                         scfcp->scfc_in = true;
404                 }
405                 smp_call_function_many(cpu_online_mask, scf_handler, scfcp, scfsp->scfs_wait);
406                 break;
407         case SCF_PRIM_ALL:
408                 if (scfsp->scfs_wait)
409                         scfp->n_all_wait++;
410                 else
411                         scfp->n_all++;
412                 if (scfcp) {
413                         barrier(); // Prevent race-reduction compiler optimizations.
414                         scfcp->scfc_in = true;
415                 }
416                 smp_call_function(scf_handler, scfcp, scfsp->scfs_wait);
417                 break;
418         default:
419                 WARN_ON_ONCE(1);
420                 if (scfcp)
421                         scfcp->scfc_out = true;
422         }
423         if (scfcp && scfsp->scfs_wait) {
424                 if (WARN_ON_ONCE((num_online_cpus() > 1 || scfsp->scfs_prim == SCF_PRIM_SINGLE) &&
425                                  !scfcp->scfc_out)) {
426                         pr_warn("%s: Memory-ordering failure, scfs_prim: %d.\n", __func__, scfsp->scfs_prim);
427                         atomic_inc(&n_mb_out_errs); // Leak rather than trash!
428                 } else {
429                         kfree(scfcp);
430                 }
431                 barrier(); // Prevent race-reduction compiler optimizations.
432         }
433         if (use_cpus_read_lock)
434                 cpus_read_unlock();
435         else
436                 preempt_enable();
437         if (!(torture_random(trsp) & 0xfff))
438                 schedule_timeout_uninterruptible(1);
439 }
440
441 // SCF test kthread.  Repeatedly does calls to members of the
442 // smp_call_function() family of functions.
443 static int scftorture_invoker(void *arg)
444 {
445         int cpu;
446         int curcpu;
447         DEFINE_TORTURE_RANDOM(rand);
448         struct scf_statistics *scfp = (struct scf_statistics *)arg;
449         bool was_offline = false;
450
451         VERBOSE_SCFTORTOUT("scftorture_invoker %d: task started", scfp->cpu);
452         cpu = scfp->cpu % nr_cpu_ids;
453         WARN_ON_ONCE(set_cpus_allowed_ptr(current, cpumask_of(cpu)));
454         set_user_nice(current, MAX_NICE);
455         if (holdoff)
456                 schedule_timeout_interruptible(holdoff * HZ);
457
458         VERBOSE_SCFTORTOUT("scftorture_invoker %d: Waiting for all SCF torturers from cpu %d", scfp->cpu, raw_smp_processor_id());
459
460         // Make sure that the CPU is affinitized appropriately during testing.
461         curcpu = raw_smp_processor_id();
462         WARN_ONCE(curcpu != scfp->cpu % nr_cpu_ids,
463                   "%s: Wanted CPU %d, running on %d, nr_cpu_ids = %d\n",
464                   __func__, scfp->cpu, curcpu, nr_cpu_ids);
465
466         if (!atomic_dec_return(&n_started))
467                 while (atomic_read_acquire(&n_started)) {
468                         if (torture_must_stop()) {
469                                 VERBOSE_SCFTORTOUT("scftorture_invoker %d ended before starting", scfp->cpu);
470                                 goto end;
471                         }
472                         schedule_timeout_uninterruptible(1);
473                 }
474
475         VERBOSE_SCFTORTOUT("scftorture_invoker %d started", scfp->cpu);
476
477         do {
478                 scftorture_invoke_one(scfp, &rand);
479                 while (cpu_is_offline(cpu) && !torture_must_stop()) {
480                         schedule_timeout_interruptible(HZ / 5);
481                         was_offline = true;
482                 }
483                 if (was_offline) {
484                         set_cpus_allowed_ptr(current, cpumask_of(cpu));
485                         was_offline = false;
486                 }
487                 cond_resched();
488                 stutter_wait("scftorture_invoker");
489         } while (!torture_must_stop());
490
491         VERBOSE_SCFTORTOUT("scftorture_invoker %d ended", scfp->cpu);
492 end:
493         torture_kthread_stopping("scftorture_invoker");
494         return 0;
495 }
496
497 static void
498 scftorture_print_module_parms(const char *tag)
499 {
500         pr_alert(SCFTORT_FLAG
501                  "--- %s:  verbose=%d holdoff=%d longwait=%d nthreads=%d onoff_holdoff=%d onoff_interval=%d shutdown_secs=%d stat_interval=%d stutter=%d use_cpus_read_lock=%d, weight_resched=%d, weight_single=%d, weight_single_rpc=%d, weight_single_wait=%d, weight_many=%d, weight_many_wait=%d, weight_all=%d, weight_all_wait=%d\n", tag,
502                  verbose, holdoff, longwait, nthreads, onoff_holdoff, onoff_interval, shutdown, stat_interval, stutter, use_cpus_read_lock, weight_resched, weight_single, weight_single_rpc, weight_single_wait, weight_many, weight_many_wait, weight_all, weight_all_wait);
503 }
504
505 static void scf_cleanup_handler(void *unused)
506 {
507 }
508
509 static void scf_torture_cleanup(void)
510 {
511         int i;
512
513         if (torture_cleanup_begin())
514                 return;
515
516         WRITE_ONCE(scfdone, true);
517         if (nthreads && scf_stats_p)
518                 for (i = 0; i < nthreads; i++)
519                         torture_stop_kthread("scftorture_invoker", scf_stats_p[i].task);
520         else
521                 goto end;
522         smp_call_function(scf_cleanup_handler, NULL, 0);
523         torture_stop_kthread(scf_torture_stats, scf_torture_stats_task);
524         scf_torture_stats_print();  // -After- the stats thread is stopped!
525         kfree(scf_stats_p);  // -After- the last stats print has completed!
526         scf_stats_p = NULL;
527
528         if (atomic_read(&n_errs) || atomic_read(&n_mb_in_errs) || atomic_read(&n_mb_out_errs))
529                 scftorture_print_module_parms("End of test: FAILURE");
530         else if (torture_onoff_failures())
531                 scftorture_print_module_parms("End of test: LOCK_HOTPLUG");
532         else
533                 scftorture_print_module_parms("End of test: SUCCESS");
534
535 end:
536         torture_cleanup_end();
537 }
538
539 static int __init scf_torture_init(void)
540 {
541         long i;
542         int firsterr = 0;
543         unsigned long weight_resched1 = weight_resched;
544         unsigned long weight_single1 = weight_single;
545         unsigned long weight_single_rpc1 = weight_single_rpc;
546         unsigned long weight_single_wait1 = weight_single_wait;
547         unsigned long weight_many1 = weight_many;
548         unsigned long weight_many_wait1 = weight_many_wait;
549         unsigned long weight_all1 = weight_all;
550         unsigned long weight_all_wait1 = weight_all_wait;
551
552         if (!torture_init_begin(SCFTORT_STRING, verbose))
553                 return -EBUSY;
554
555         scftorture_print_module_parms("Start of test");
556
557         if (weight_resched <= 0 &&
558             weight_single <= 0 && weight_single_rpc <= 0 && weight_single_wait <= 0 &&
559             weight_many <= 0 && weight_many_wait <= 0 &&
560             weight_all <= 0 && weight_all_wait <= 0) {
561                 weight_resched1 = weight_resched == 0 ? 0 : 2 * nr_cpu_ids;
562                 weight_single1 = weight_single == 0 ? 0 : 2 * nr_cpu_ids;
563                 weight_single_rpc1 = weight_single_rpc == 0 ? 0 : 2 * nr_cpu_ids;
564                 weight_single_wait1 = weight_single_wait == 0 ? 0 : 2 * nr_cpu_ids;
565                 weight_many1 = weight_many == 0 ? 0 : 2;
566                 weight_many_wait1 = weight_many_wait == 0 ? 0 : 2;
567                 weight_all1 = weight_all == 0 ? 0 : 1;
568                 weight_all_wait1 = weight_all_wait == 0 ? 0 : 1;
569         } else {
570                 if (weight_resched == -1)
571                         weight_resched1 = 0;
572                 if (weight_single == -1)
573                         weight_single1 = 0;
574                 if (weight_single_rpc == -1)
575                         weight_single_rpc1 = 0;
576                 if (weight_single_wait == -1)
577                         weight_single_wait1 = 0;
578                 if (weight_many == -1)
579                         weight_many1 = 0;
580                 if (weight_many_wait == -1)
581                         weight_many_wait1 = 0;
582                 if (weight_all == -1)
583                         weight_all1 = 0;
584                 if (weight_all_wait == -1)
585                         weight_all_wait1 = 0;
586         }
587         if (weight_resched1 == 0 && weight_single1 == 0 && weight_single_rpc1 == 0 &&
588             weight_single_wait1 == 0 && weight_many1 == 0 && weight_many_wait1 == 0 &&
589             weight_all1 == 0 && weight_all_wait1 == 0) {
590                 VERBOSE_SCFTORTOUT_ERRSTRING("all zero weights makes no sense");
591                 firsterr = -EINVAL;
592                 goto unwind;
593         }
594         if (IS_BUILTIN(CONFIG_SCF_TORTURE_TEST))
595                 scf_sel_add(weight_resched1, SCF_PRIM_RESCHED, false);
596         else if (weight_resched1)
597                 VERBOSE_SCFTORTOUT_ERRSTRING("built as module, weight_resched ignored");
598         scf_sel_add(weight_single1, SCF_PRIM_SINGLE, false);
599         scf_sel_add(weight_single_rpc1, SCF_PRIM_SINGLE_RPC, true);
600         scf_sel_add(weight_single_wait1, SCF_PRIM_SINGLE, true);
601         scf_sel_add(weight_many1, SCF_PRIM_MANY, false);
602         scf_sel_add(weight_many_wait1, SCF_PRIM_MANY, true);
603         scf_sel_add(weight_all1, SCF_PRIM_ALL, false);
604         scf_sel_add(weight_all_wait1, SCF_PRIM_ALL, true);
605         scf_sel_dump();
606
607         if (onoff_interval > 0) {
608                 firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval, NULL);
609                 if (torture_init_error(firsterr))
610                         goto unwind;
611         }
612         if (shutdown_secs > 0) {
613                 firsterr = torture_shutdown_init(shutdown_secs, scf_torture_cleanup);
614                 if (torture_init_error(firsterr))
615                         goto unwind;
616         }
617         if (stutter > 0) {
618                 firsterr = torture_stutter_init(stutter, stutter);
619                 if (torture_init_error(firsterr))
620                         goto unwind;
621         }
622
623         // Worker tasks invoking smp_call_function().
624         if (nthreads < 0)
625                 nthreads = num_online_cpus();
626         scf_stats_p = kcalloc(nthreads, sizeof(scf_stats_p[0]), GFP_KERNEL);
627         if (!scf_stats_p) {
628                 VERBOSE_SCFTORTOUT_ERRSTRING("out of memory");
629                 firsterr = -ENOMEM;
630                 goto unwind;
631         }
632
633         VERBOSE_SCFTORTOUT("Starting %d smp_call_function() threads\n", nthreads);
634
635         atomic_set(&n_started, nthreads);
636         for (i = 0; i < nthreads; i++) {
637                 scf_stats_p[i].cpu = i;
638                 firsterr = torture_create_kthread(scftorture_invoker, (void *)&scf_stats_p[i],
639                                                   scf_stats_p[i].task);
640                 if (torture_init_error(firsterr))
641                         goto unwind;
642         }
643         if (stat_interval > 0) {
644                 firsterr = torture_create_kthread(scf_torture_stats, NULL, scf_torture_stats_task);
645                 if (torture_init_error(firsterr))
646                         goto unwind;
647         }
648
649         torture_init_end();
650         return 0;
651
652 unwind:
653         torture_init_end();
654         scf_torture_cleanup();
655         if (shutdown_secs) {
656                 WARN_ON(!IS_MODULE(CONFIG_SCF_TORTURE_TEST));
657                 kernel_power_off();
658         }
659         return firsterr;
660 }
661
662 module_init(scf_torture_init);
663 module_exit(scf_torture_cleanup);