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