1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *    Copyright IBM Corp. 2007, 2011
4  */
5 
6 #define KMSG_COMPONENT "cpu"
7 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
8 
9 #include <linux/workqueue.h>
10 #include <linux/memblock.h>
11 #include <linux/uaccess.h>
12 #include <linux/sysctl.h>
13 #include <linux/cpuset.h>
14 #include <linux/device.h>
15 #include <linux/export.h>
16 #include <linux/kernel.h>
17 #include <linux/sched.h>
18 #include <linux/sched/topology.h>
19 #include <linux/delay.h>
20 #include <linux/init.h>
21 #include <linux/slab.h>
22 #include <linux/cpu.h>
23 #include <linux/smp.h>
24 #include <linux/mm.h>
25 #include <linux/nodemask.h>
26 #include <linux/node.h>
27 #include <asm/sysinfo.h>
28 
29 #define PTF_HORIZONTAL	(0UL)
30 #define PTF_VERTICAL	(1UL)
31 #define PTF_CHECK	(2UL)
32 
33 enum {
34 	TOPOLOGY_MODE_HW,
35 	TOPOLOGY_MODE_SINGLE,
36 	TOPOLOGY_MODE_PACKAGE,
37 	TOPOLOGY_MODE_UNINITIALIZED
38 };
39 
40 struct mask_info {
41 	struct mask_info *next;
42 	unsigned char id;
43 	cpumask_t mask;
44 };
45 
46 static int topology_mode = TOPOLOGY_MODE_UNINITIALIZED;
47 static void set_topology_timer(void);
48 static void topology_work_fn(struct work_struct *work);
49 static struct sysinfo_15_1_x *tl_info;
50 
51 static DECLARE_WORK(topology_work, topology_work_fn);
52 
53 /*
54  * Socket/Book linked lists and cpu_topology updates are
55  * protected by "sched_domains_mutex".
56  */
57 static struct mask_info socket_info;
58 static struct mask_info book_info;
59 static struct mask_info drawer_info;
60 
61 struct cpu_topology_s390 cpu_topology[NR_CPUS];
62 EXPORT_SYMBOL_GPL(cpu_topology);
63 
cpu_group_map(cpumask_t * dst,struct mask_info * info,unsigned int cpu)64 static void cpu_group_map(cpumask_t *dst, struct mask_info *info, unsigned int cpu)
65 {
66 	static cpumask_t mask;
67 
68 	cpumask_clear(&mask);
69 	if (!cpumask_test_cpu(cpu, &cpu_setup_mask))
70 		goto out;
71 	cpumask_set_cpu(cpu, &mask);
72 	switch (topology_mode) {
73 	case TOPOLOGY_MODE_HW:
74 		while (info) {
75 			if (cpumask_test_cpu(cpu, &info->mask)) {
76 				cpumask_copy(&mask, &info->mask);
77 				break;
78 			}
79 			info = info->next;
80 		}
81 		break;
82 	case TOPOLOGY_MODE_PACKAGE:
83 		cpumask_copy(&mask, cpu_present_mask);
84 		break;
85 	default:
86 		fallthrough;
87 	case TOPOLOGY_MODE_SINGLE:
88 		break;
89 	}
90 	cpumask_and(&mask, &mask, &cpu_setup_mask);
91 out:
92 	cpumask_copy(dst, &mask);
93 }
94 
cpu_thread_map(cpumask_t * dst,unsigned int cpu)95 static void cpu_thread_map(cpumask_t *dst, unsigned int cpu)
96 {
97 	static cpumask_t mask;
98 	int i;
99 
100 	cpumask_clear(&mask);
101 	if (!cpumask_test_cpu(cpu, &cpu_setup_mask))
102 		goto out;
103 	cpumask_set_cpu(cpu, &mask);
104 	if (topology_mode != TOPOLOGY_MODE_HW)
105 		goto out;
106 	cpu -= cpu % (smp_cpu_mtid + 1);
107 	for (i = 0; i <= smp_cpu_mtid; i++) {
108 		if (cpumask_test_cpu(cpu + i, &cpu_setup_mask))
109 			cpumask_set_cpu(cpu + i, &mask);
110 	}
111 out:
112 	cpumask_copy(dst, &mask);
113 }
114 
115 #define TOPOLOGY_CORE_BITS	64
116 
add_cpus_to_mask(struct topology_core * tl_core,struct mask_info * drawer,struct mask_info * book,struct mask_info * socket)117 static void add_cpus_to_mask(struct topology_core *tl_core,
118 			     struct mask_info *drawer,
119 			     struct mask_info *book,
120 			     struct mask_info *socket)
121 {
122 	struct cpu_topology_s390 *topo;
123 	unsigned int core;
124 
125 	for_each_set_bit(core, &tl_core->mask, TOPOLOGY_CORE_BITS) {
126 		unsigned int rcore;
127 		int lcpu, i;
128 
129 		rcore = TOPOLOGY_CORE_BITS - 1 - core + tl_core->origin;
130 		lcpu = smp_find_processor_id(rcore << smp_cpu_mt_shift);
131 		if (lcpu < 0)
132 			continue;
133 		for (i = 0; i <= smp_cpu_mtid; i++) {
134 			topo = &cpu_topology[lcpu + i];
135 			topo->drawer_id = drawer->id;
136 			topo->book_id = book->id;
137 			topo->socket_id = socket->id;
138 			topo->core_id = rcore;
139 			topo->thread_id = lcpu + i;
140 			topo->dedicated = tl_core->d;
141 			cpumask_set_cpu(lcpu + i, &drawer->mask);
142 			cpumask_set_cpu(lcpu + i, &book->mask);
143 			cpumask_set_cpu(lcpu + i, &socket->mask);
144 			smp_cpu_set_polarization(lcpu + i, tl_core->pp);
145 		}
146 	}
147 }
148 
clear_masks(void)149 static void clear_masks(void)
150 {
151 	struct mask_info *info;
152 
153 	info = &socket_info;
154 	while (info) {
155 		cpumask_clear(&info->mask);
156 		info = info->next;
157 	}
158 	info = &book_info;
159 	while (info) {
160 		cpumask_clear(&info->mask);
161 		info = info->next;
162 	}
163 	info = &drawer_info;
164 	while (info) {
165 		cpumask_clear(&info->mask);
166 		info = info->next;
167 	}
168 }
169 
next_tle(union topology_entry * tle)170 static union topology_entry *next_tle(union topology_entry *tle)
171 {
172 	if (!tle->nl)
173 		return (union topology_entry *)((struct topology_core *)tle + 1);
174 	return (union topology_entry *)((struct topology_container *)tle + 1);
175 }
176 
tl_to_masks(struct sysinfo_15_1_x * info)177 static void tl_to_masks(struct sysinfo_15_1_x *info)
178 {
179 	struct mask_info *socket = &socket_info;
180 	struct mask_info *book = &book_info;
181 	struct mask_info *drawer = &drawer_info;
182 	union topology_entry *tle, *end;
183 
184 	clear_masks();
185 	tle = info->tle;
186 	end = (union topology_entry *)((unsigned long)info + info->length);
187 	while (tle < end) {
188 		switch (tle->nl) {
189 		case 3:
190 			drawer = drawer->next;
191 			drawer->id = tle->container.id;
192 			break;
193 		case 2:
194 			book = book->next;
195 			book->id = tle->container.id;
196 			break;
197 		case 1:
198 			socket = socket->next;
199 			socket->id = tle->container.id;
200 			break;
201 		case 0:
202 			add_cpus_to_mask(&tle->cpu, drawer, book, socket);
203 			break;
204 		default:
205 			clear_masks();
206 			return;
207 		}
208 		tle = next_tle(tle);
209 	}
210 }
211 
topology_update_polarization_simple(void)212 static void topology_update_polarization_simple(void)
213 {
214 	int cpu;
215 
216 	for_each_possible_cpu(cpu)
217 		smp_cpu_set_polarization(cpu, POLARIZATION_HRZ);
218 }
219 
ptf(unsigned long fc)220 static int ptf(unsigned long fc)
221 {
222 	int rc;
223 
224 	asm volatile(
225 		"	.insn	rre,0xb9a20000,%1,%1\n"
226 		"	ipm	%0\n"
227 		"	srl	%0,28\n"
228 		: "=d" (rc)
229 		: "d" (fc)  : "cc");
230 	return rc;
231 }
232 
topology_set_cpu_management(int fc)233 int topology_set_cpu_management(int fc)
234 {
235 	int cpu, rc;
236 
237 	if (!MACHINE_HAS_TOPOLOGY)
238 		return -EOPNOTSUPP;
239 	if (fc)
240 		rc = ptf(PTF_VERTICAL);
241 	else
242 		rc = ptf(PTF_HORIZONTAL);
243 	if (rc)
244 		return -EBUSY;
245 	for_each_possible_cpu(cpu)
246 		smp_cpu_set_polarization(cpu, POLARIZATION_UNKNOWN);
247 	return rc;
248 }
249 
update_cpu_masks(void)250 void update_cpu_masks(void)
251 {
252 	struct cpu_topology_s390 *topo, *topo_package, *topo_sibling;
253 	int cpu, sibling, pkg_first, smt_first, id;
254 
255 	for_each_possible_cpu(cpu) {
256 		topo = &cpu_topology[cpu];
257 		cpu_thread_map(&topo->thread_mask, cpu);
258 		cpu_group_map(&topo->core_mask, &socket_info, cpu);
259 		cpu_group_map(&topo->book_mask, &book_info, cpu);
260 		cpu_group_map(&topo->drawer_mask, &drawer_info, cpu);
261 		topo->booted_cores = 0;
262 		if (topology_mode != TOPOLOGY_MODE_HW) {
263 			id = topology_mode == TOPOLOGY_MODE_PACKAGE ? 0 : cpu;
264 			topo->thread_id = cpu;
265 			topo->core_id = cpu;
266 			topo->socket_id = id;
267 			topo->book_id = id;
268 			topo->drawer_id = id;
269 		}
270 	}
271 	for_each_online_cpu(cpu) {
272 		topo = &cpu_topology[cpu];
273 		pkg_first = cpumask_first(&topo->core_mask);
274 		topo_package = &cpu_topology[pkg_first];
275 		if (cpu == pkg_first) {
276 			for_each_cpu(sibling, &topo->core_mask) {
277 				topo_sibling = &cpu_topology[sibling];
278 				smt_first = cpumask_first(&topo_sibling->thread_mask);
279 				if (sibling == smt_first)
280 					topo_package->booted_cores++;
281 			}
282 		} else {
283 			topo->booted_cores = topo_package->booted_cores;
284 		}
285 	}
286 }
287 
store_topology(struct sysinfo_15_1_x * info)288 void store_topology(struct sysinfo_15_1_x *info)
289 {
290 	stsi(info, 15, 1, topology_mnest_limit());
291 }
292 
__arch_update_dedicated_flag(void * arg)293 static void __arch_update_dedicated_flag(void *arg)
294 {
295 	if (topology_cpu_dedicated(smp_processor_id()))
296 		set_cpu_flag(CIF_DEDICATED_CPU);
297 	else
298 		clear_cpu_flag(CIF_DEDICATED_CPU);
299 }
300 
__arch_update_cpu_topology(void)301 static int __arch_update_cpu_topology(void)
302 {
303 	struct sysinfo_15_1_x *info = tl_info;
304 	int rc = 0;
305 
306 	mutex_lock(&smp_cpu_state_mutex);
307 	if (MACHINE_HAS_TOPOLOGY) {
308 		rc = 1;
309 		store_topology(info);
310 		tl_to_masks(info);
311 	}
312 	update_cpu_masks();
313 	if (!MACHINE_HAS_TOPOLOGY)
314 		topology_update_polarization_simple();
315 	mutex_unlock(&smp_cpu_state_mutex);
316 	return rc;
317 }
318 
arch_update_cpu_topology(void)319 int arch_update_cpu_topology(void)
320 {
321 	struct device *dev;
322 	int cpu, rc;
323 
324 	rc = __arch_update_cpu_topology();
325 	on_each_cpu(__arch_update_dedicated_flag, NULL, 0);
326 	for_each_online_cpu(cpu) {
327 		dev = get_cpu_device(cpu);
328 		if (dev)
329 			kobject_uevent(&dev->kobj, KOBJ_CHANGE);
330 	}
331 	return rc;
332 }
333 
topology_work_fn(struct work_struct * work)334 static void topology_work_fn(struct work_struct *work)
335 {
336 	rebuild_sched_domains();
337 }
338 
topology_schedule_update(void)339 void topology_schedule_update(void)
340 {
341 	schedule_work(&topology_work);
342 }
343 
topology_flush_work(void)344 static void topology_flush_work(void)
345 {
346 	flush_work(&topology_work);
347 }
348 
topology_timer_fn(struct timer_list * unused)349 static void topology_timer_fn(struct timer_list *unused)
350 {
351 	if (ptf(PTF_CHECK))
352 		topology_schedule_update();
353 	set_topology_timer();
354 }
355 
356 static struct timer_list topology_timer;
357 
358 static atomic_t topology_poll = ATOMIC_INIT(0);
359 
set_topology_timer(void)360 static void set_topology_timer(void)
361 {
362 	if (atomic_add_unless(&topology_poll, -1, 0))
363 		mod_timer(&topology_timer, jiffies + msecs_to_jiffies(100));
364 	else
365 		mod_timer(&topology_timer, jiffies + msecs_to_jiffies(60 * MSEC_PER_SEC));
366 }
367 
topology_expect_change(void)368 void topology_expect_change(void)
369 {
370 	if (!MACHINE_HAS_TOPOLOGY)
371 		return;
372 	/* This is racy, but it doesn't matter since it is just a heuristic.
373 	 * Worst case is that we poll in a higher frequency for a bit longer.
374 	 */
375 	if (atomic_read(&topology_poll) > 60)
376 		return;
377 	atomic_add(60, &topology_poll);
378 	set_topology_timer();
379 }
380 
381 static int cpu_management;
382 
dispatching_show(struct device * dev,struct device_attribute * attr,char * buf)383 static ssize_t dispatching_show(struct device *dev,
384 				struct device_attribute *attr,
385 				char *buf)
386 {
387 	ssize_t count;
388 
389 	mutex_lock(&smp_cpu_state_mutex);
390 	count = sprintf(buf, "%d\n", cpu_management);
391 	mutex_unlock(&smp_cpu_state_mutex);
392 	return count;
393 }
394 
dispatching_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)395 static ssize_t dispatching_store(struct device *dev,
396 				 struct device_attribute *attr,
397 				 const char *buf,
398 				 size_t count)
399 {
400 	int val, rc;
401 	char delim;
402 
403 	if (sscanf(buf, "%d %c", &val, &delim) != 1)
404 		return -EINVAL;
405 	if (val != 0 && val != 1)
406 		return -EINVAL;
407 	rc = 0;
408 	cpus_read_lock();
409 	mutex_lock(&smp_cpu_state_mutex);
410 	if (cpu_management == val)
411 		goto out;
412 	rc = topology_set_cpu_management(val);
413 	if (rc)
414 		goto out;
415 	cpu_management = val;
416 	topology_expect_change();
417 out:
418 	mutex_unlock(&smp_cpu_state_mutex);
419 	cpus_read_unlock();
420 	return rc ? rc : count;
421 }
422 static DEVICE_ATTR_RW(dispatching);
423 
cpu_polarization_show(struct device * dev,struct device_attribute * attr,char * buf)424 static ssize_t cpu_polarization_show(struct device *dev,
425 				     struct device_attribute *attr, char *buf)
426 {
427 	int cpu = dev->id;
428 	ssize_t count;
429 
430 	mutex_lock(&smp_cpu_state_mutex);
431 	switch (smp_cpu_get_polarization(cpu)) {
432 	case POLARIZATION_HRZ:
433 		count = sprintf(buf, "horizontal\n");
434 		break;
435 	case POLARIZATION_VL:
436 		count = sprintf(buf, "vertical:low\n");
437 		break;
438 	case POLARIZATION_VM:
439 		count = sprintf(buf, "vertical:medium\n");
440 		break;
441 	case POLARIZATION_VH:
442 		count = sprintf(buf, "vertical:high\n");
443 		break;
444 	default:
445 		count = sprintf(buf, "unknown\n");
446 		break;
447 	}
448 	mutex_unlock(&smp_cpu_state_mutex);
449 	return count;
450 }
451 static DEVICE_ATTR(polarization, 0444, cpu_polarization_show, NULL);
452 
453 static struct attribute *topology_cpu_attrs[] = {
454 	&dev_attr_polarization.attr,
455 	NULL,
456 };
457 
458 static struct attribute_group topology_cpu_attr_group = {
459 	.attrs = topology_cpu_attrs,
460 };
461 
cpu_dedicated_show(struct device * dev,struct device_attribute * attr,char * buf)462 static ssize_t cpu_dedicated_show(struct device *dev,
463 				  struct device_attribute *attr, char *buf)
464 {
465 	int cpu = dev->id;
466 	ssize_t count;
467 
468 	mutex_lock(&smp_cpu_state_mutex);
469 	count = sprintf(buf, "%d\n", topology_cpu_dedicated(cpu));
470 	mutex_unlock(&smp_cpu_state_mutex);
471 	return count;
472 }
473 static DEVICE_ATTR(dedicated, 0444, cpu_dedicated_show, NULL);
474 
475 static struct attribute *topology_extra_cpu_attrs[] = {
476 	&dev_attr_dedicated.attr,
477 	NULL,
478 };
479 
480 static struct attribute_group topology_extra_cpu_attr_group = {
481 	.attrs = topology_extra_cpu_attrs,
482 };
483 
topology_cpu_init(struct cpu * cpu)484 int topology_cpu_init(struct cpu *cpu)
485 {
486 	int rc;
487 
488 	rc = sysfs_create_group(&cpu->dev.kobj, &topology_cpu_attr_group);
489 	if (rc || !MACHINE_HAS_TOPOLOGY)
490 		return rc;
491 	rc = sysfs_create_group(&cpu->dev.kobj, &topology_extra_cpu_attr_group);
492 	if (rc)
493 		sysfs_remove_group(&cpu->dev.kobj, &topology_cpu_attr_group);
494 	return rc;
495 }
496 
cpu_thread_mask(int cpu)497 static const struct cpumask *cpu_thread_mask(int cpu)
498 {
499 	return &cpu_topology[cpu].thread_mask;
500 }
501 
502 
cpu_coregroup_mask(int cpu)503 const struct cpumask *cpu_coregroup_mask(int cpu)
504 {
505 	return &cpu_topology[cpu].core_mask;
506 }
507 
cpu_book_mask(int cpu)508 static const struct cpumask *cpu_book_mask(int cpu)
509 {
510 	return &cpu_topology[cpu].book_mask;
511 }
512 
cpu_drawer_mask(int cpu)513 static const struct cpumask *cpu_drawer_mask(int cpu)
514 {
515 	return &cpu_topology[cpu].drawer_mask;
516 }
517 
518 static struct sched_domain_topology_level s390_topology[] = {
519 	{ cpu_thread_mask, cpu_smt_flags, SD_INIT_NAME(SMT) },
520 	{ cpu_coregroup_mask, cpu_core_flags, SD_INIT_NAME(MC) },
521 	{ cpu_book_mask, SD_INIT_NAME(BOOK) },
522 	{ cpu_drawer_mask, SD_INIT_NAME(DRAWER) },
523 	{ cpu_cpu_mask, SD_INIT_NAME(DIE) },
524 	{ NULL, },
525 };
526 
alloc_masks(struct sysinfo_15_1_x * info,struct mask_info * mask,int offset)527 static void __init alloc_masks(struct sysinfo_15_1_x *info,
528 			       struct mask_info *mask, int offset)
529 {
530 	int i, nr_masks;
531 
532 	nr_masks = info->mag[TOPOLOGY_NR_MAG - offset];
533 	for (i = 0; i < info->mnest - offset; i++)
534 		nr_masks *= info->mag[TOPOLOGY_NR_MAG - offset - 1 - i];
535 	nr_masks = max(nr_masks, 1);
536 	for (i = 0; i < nr_masks; i++) {
537 		mask->next = memblock_alloc(sizeof(*mask->next), 8);
538 		if (!mask->next)
539 			panic("%s: Failed to allocate %zu bytes align=0x%x\n",
540 			      __func__, sizeof(*mask->next), 8);
541 		mask = mask->next;
542 	}
543 }
544 
topology_init_early(void)545 void __init topology_init_early(void)
546 {
547 	struct sysinfo_15_1_x *info;
548 
549 	set_sched_topology(s390_topology);
550 	if (topology_mode == TOPOLOGY_MODE_UNINITIALIZED) {
551 		if (MACHINE_HAS_TOPOLOGY)
552 			topology_mode = TOPOLOGY_MODE_HW;
553 		else
554 			topology_mode = TOPOLOGY_MODE_SINGLE;
555 	}
556 	if (!MACHINE_HAS_TOPOLOGY)
557 		goto out;
558 	tl_info = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
559 	if (!tl_info)
560 		panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
561 		      __func__, PAGE_SIZE, PAGE_SIZE);
562 	info = tl_info;
563 	store_topology(info);
564 	pr_info("The CPU configuration topology of the machine is: %d %d %d %d %d %d / %d\n",
565 		info->mag[0], info->mag[1], info->mag[2], info->mag[3],
566 		info->mag[4], info->mag[5], info->mnest);
567 	alloc_masks(info, &socket_info, 1);
568 	alloc_masks(info, &book_info, 2);
569 	alloc_masks(info, &drawer_info, 3);
570 out:
571 	cpumask_set_cpu(0, &cpu_setup_mask);
572 	__arch_update_cpu_topology();
573 	__arch_update_dedicated_flag(NULL);
574 }
575 
topology_get_mode(int enabled)576 static inline int topology_get_mode(int enabled)
577 {
578 	if (!enabled)
579 		return TOPOLOGY_MODE_SINGLE;
580 	return MACHINE_HAS_TOPOLOGY ? TOPOLOGY_MODE_HW : TOPOLOGY_MODE_PACKAGE;
581 }
582 
topology_is_enabled(void)583 static inline int topology_is_enabled(void)
584 {
585 	return topology_mode != TOPOLOGY_MODE_SINGLE;
586 }
587 
topology_setup(char * str)588 static int __init topology_setup(char *str)
589 {
590 	bool enabled;
591 	int rc;
592 
593 	rc = kstrtobool(str, &enabled);
594 	if (rc)
595 		return rc;
596 	topology_mode = topology_get_mode(enabled);
597 	return 0;
598 }
599 early_param("topology", topology_setup);
600 
topology_ctl_handler(struct ctl_table * ctl,int write,void * buffer,size_t * lenp,loff_t * ppos)601 static int topology_ctl_handler(struct ctl_table *ctl, int write,
602 				void *buffer, size_t *lenp, loff_t *ppos)
603 {
604 	int enabled = topology_is_enabled();
605 	int new_mode;
606 	int rc;
607 	struct ctl_table ctl_entry = {
608 		.procname	= ctl->procname,
609 		.data		= &enabled,
610 		.maxlen		= sizeof(int),
611 		.extra1		= SYSCTL_ZERO,
612 		.extra2		= SYSCTL_ONE,
613 	};
614 
615 	rc = proc_douintvec_minmax(&ctl_entry, write, buffer, lenp, ppos);
616 	if (rc < 0 || !write)
617 		return rc;
618 
619 	mutex_lock(&smp_cpu_state_mutex);
620 	new_mode = topology_get_mode(enabled);
621 	if (topology_mode != new_mode) {
622 		topology_mode = new_mode;
623 		topology_schedule_update();
624 	}
625 	mutex_unlock(&smp_cpu_state_mutex);
626 	topology_flush_work();
627 
628 	return rc;
629 }
630 
631 static struct ctl_table topology_ctl_table[] = {
632 	{
633 		.procname	= "topology",
634 		.mode		= 0644,
635 		.proc_handler	= topology_ctl_handler,
636 	},
637 	{ },
638 };
639 
640 static struct ctl_table topology_dir_table[] = {
641 	{
642 		.procname	= "s390",
643 		.maxlen		= 0,
644 		.mode		= 0555,
645 		.child		= topology_ctl_table,
646 	},
647 	{ },
648 };
649 
topology_init(void)650 static int __init topology_init(void)
651 {
652 	timer_setup(&topology_timer, topology_timer_fn, TIMER_DEFERRABLE);
653 	if (MACHINE_HAS_TOPOLOGY)
654 		set_topology_timer();
655 	else
656 		topology_update_polarization_simple();
657 	register_sysctl_table(topology_dir_table);
658 	return device_create_file(cpu_subsys.dev_root, &dev_attr_dispatching);
659 }
660 device_initcall(topology_init);
661