summaryrefslogtreecommitdiffstats
path: root/kernel/smp.c
blob: db2f73808db527c4bf2efac579db166cfad27fcb (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Generic helpers for smp ipi calls
 *
 * (C) Jens Axboe <jens.axboe@oracle.com> 2008
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/irq_work.h>
#include <linux/rcupdate.h>
#include <linux/rculist.h>
#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/percpu.h>
#include <linux/init.h>
#include <linux/gfp.h>
#include <linux/smp.h>
#include <linux/cpu.h>
#include <linux/sched.h>
#include <linux/sched/idle.h>
#include <linux/hypervisor.h>

#include "smpboot.h"

enum {
	CSD_FLAG_LOCK		= 0x01,
	CSD_FLAG_SYNCHRONOUS	= 0x02,
};

struct call_function_data {
	call_single_data_t	__percpu *csd;
	cpumask_var_t		cpumask;
	cpumask_var_t		cpumask_ipi;
};

static DEFINE_PER_CPU_ALIGNED(struct call_function_data, cfd_data);

static DEFINE_PER_CPU_SHARED_ALIGNED(struct llist_head, call_single_queue);

static void flush_smp_call_function_queue(bool warn_cpu_offline);

int smpcfd_prepare_cpu(unsigned int cpu)
{
	struct call_function_data *cfd = &per_cpu(cfd_data, cpu);

	if (!zalloc_cpumask_var_node(&cfd->cpumask, GFP_KERNEL,
				     cpu_to_node(cpu)))
		return -ENOMEM;
	if (!zalloc_cpumask_var_node(&cfd->cpumask_ipi, GFP_KERNEL,
				     cpu_to_node(cpu))) {
		free_cpumask_var(cfd->cpumask);
		return -ENOMEM;
	}
	cfd->csd = alloc_percpu(call_single_data_t);
	if (!cfd->csd) {
		free_cpumask_var(cfd->cpumask);
		free_cpumask_var(cfd->cpumask_ipi);
		return -ENOMEM;
	}

	return 0;
}

int smpcfd_dead_cpu(unsigned int cpu)
{
	struct call_function_data *cfd = &per_cpu(cfd_data, cpu);

	free_cpumask_var(cfd->cpumask);
	free_cpumask_var(cfd->cpumask_ipi);
	free_percpu(cfd->csd);
	return 0;
}

int smpcfd_dying_cpu(unsigned int cpu)
{
	/*
	 * The IPIs for the smp-call-function callbacks queued by other
	 * CPUs might arrive late, either due to hardware latencies or
	 * because this CPU disabled interrupts (inside stop-machine)
	 * before the IPIs were sent. So flush out any pending callbacks
	 * explicitly (without waiting for the IPIs to arrive), to
	 * ensure that the outgoing CPU doesn't go offline with work
	 * still pending.
	 */
	flush_smp_call_function_queue(false);
	return 0;
}

void __init call_function_init(void)
{
	int i;

	for_each_possible_cpu(i)
		init_llist_head(&per_cpu(call_single_queue, i));

	smpcfd_prepare_cpu(smp_processor_id());
}

/*
 * csd_lock/csd_unlock used to serialize access to per-cpu csd resources
 *
 * For non-synchronous ipi calls the csd can still be in use by the
 * previous function call. For multi-cpu calls its even more interesting
 * as we'll have to ensure no other cpu is observing our csd.
 */
static __always_inline void csd_lock_wait(call_single_data_t *csd)
{
	smp_cond_load_acquire(&csd->flags, !(VAL & CSD_FLAG_LOCK));
}

static __always_inline void csd_lock(call_single_data_t *csd)
{
	csd_lock_wait(csd);
	csd->flags |= CSD_FLAG_LOCK;

	/*
	 * prevent CPU from reordering the above assignment
	 * to ->flags with any subsequent assignments to other
	 * fields of the specified call_single_data_t structure:
	 */
	smp_wmb();
}

static __always_inline void csd_unlock(call_single_data_t *csd)
{
	WARN_ON(!(csd->flags & CSD_FLAG_LOCK));

	/*
	 * ensure we're all done before releasing data:
	 */
	smp_store_release(&csd->flags, 0);
}

static DEFINE_PER_CPU_SHARED_ALIGNED(call_single_data_t, csd_data);

/*
 * Insert a previously allocated call_single_data_t element
 * for execution on the given CPU. data must already have
 * ->func, ->info, and ->flags set.
 */
static int generic_exec_single(int cpu, call_single_data_t *csd,
			       smp_call_func_t func, void *info)
{
	if (cpu == smp_processor_id()) {
		unsigned long flags;

		/*
		 * We can unlock early even for the synchronous on-stack case,
		 * since we're doing this from the same CPU..
		 */
		csd_unlock(csd);
		local_irq_save(flags);
		func(info);
		local_irq_restore(flags);
		return 0;
	}


	if ((unsigned)cpu >= nr_cpu_ids || !cpu_online(cpu)) {
		csd_unlock(csd);
		return -ENXIO;
	}

	csd->func = func;
	csd->info = info;

	/*
	 * The list addition should be visible before sending the IPI
	 * handler locks the list to pull the entry off it because of
	 * normal cache coherency rules implied by spinlocks.
	 *
	 * If IPIs can go out of order to the cache coherency protocol
	 * in an architecture, sufficient synchronisation should be added
	 * to arch code to make it appear to obey cache coherency WRT
	 * locking and barrier primitives. Generic code isn't really
	 * equipped to do the right thing...
	 */
	if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu)))
		arch_send_call_function_single_ipi(cpu);

	return 0;
}

/**
 * generic_smp_call_function_single_interrupt - Execute SMP IPI callbacks
 *
 * Invoked by arch to handle an IPI for call function single.
 * Must be called with interrupts disabled.
 */
void generic_smp_call_function_single_interrupt(void)
{
	flush_smp_call_function_queue(true);
}

/**
 * flush_smp_call_function_queue - Flush pending smp-call-function callbacks
 *
 * @warn_cpu_offline: If set to 'true', warn if callbacks were queued on an
 *		      offline CPU. Skip this check if set to 'false'.
 *
 * Flush any pending smp-call-function callbacks queued on this CPU. This is
 * invoked by the generic IPI handler, as well as by a CPU about to go offline,
 * to ensure that all pending IPI callbacks are run before it goes completely
 * offline.
 *
 * Loop through the call_single_queue and run all the queued callbacks.
 * Must be called with interrupts disabled.
 */
static void flush_smp_call_function_queue(bool warn_cpu_offline)
{
	call_single_data_t *csd, *csd_next;
	struct llist_node *entry, *prev;
	struct llist_head *head;
	static bool warned;

	lockdep_assert_irqs_disabled();

	head = this_cpu_ptr(&call_single_queue);
	entry = llist_del_all(head);
	entry = llist_reverse_order(entry);

	/* There shouldn't be any pending callbacks on an offline CPU. */
	if (unlikely(warn_cpu_offline && !cpu_online(smp_processor_id()) &&
		     !warned && !llist_empty(head))) {
		warned = true;
		WARN(1, "IPI on offline CPU %d\n", smp_processor_id());

		/*
		 * We don't have to use the _safe() variant here
		 * because we are not invoking the IPI handlers yet.
		 */
		llist_for_each_entry(csd, entry, llist)
			pr_warn("IPI callback %pS sent to offline CPU\n",
				csd->func);
	}

	/*
	 * First; run all SYNC callbacks, people are waiting for us.
	 */
	prev = NULL;
	llist_for_each_entry_safe(csd, csd_next, entry, llist) {
		smp_call_func_t func = csd->func;
		void *info = csd->info;

		/* Do we wait until *after* callback? */
		if (csd->flags & CSD_FLAG_SYNCHRONOUS) {
			if (prev) {
				prev->next = &csd_next->llist;
			} else {
				entry = &csd_next->llist;
			}
			func(info);
			csd_unlock(csd);
		} else {
			prev = &csd->llist;
		}
	}

	/*
	 * Second; run all !SYNC callbacks.
	 */
	llist_for_each_entry_safe(csd, csd_next, entry, llist) {
		smp_call_func_t func = csd->func;
		void *info = csd->info;

		csd_unlock(csd);
		func(info);
	}

	/*
	 * Handle irq works queued remotely by irq_work_queue_on().
	 * Smp functions above are typically synchronous so they
	 * better run first since some other CPUs may be busy waiting
	 * for them.
	 */
	irq_work_run();
}

/*
 * smp_call_function_single - Run a function on a specific CPU
 * @func: The function to run. This must be fast and non-blocking.
 * @info: An arbitrary pointer to pass to the function.
 * @wait: If true, wait until function has completed on other CPUs.
 *
 * Returns 0 on success, else a negative status code.
 */
int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
			     int wait)
{
	call_single_data_t *csd;
	call_single_data_t csd_stack = {
		.flags = CSD_FLAG_LOCK | CSD_FLAG_SYNCHRONOUS,
	};
	int this_cpu;
	int err;

	/*
	 * prevent preemption and reschedule on another processor,
	 * as well as CPU removal
	 */
	this_cpu = get_cpu();

	/*
	 * Can deadlock when called with interrupts disabled.
	 * We allow cpu's that are not yet online though, as no one else can
	 * send smp call function interrupt to this cpu and as such deadlocks
	 * can't happen.
	 */
	WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
		     && !oops_in_progress);

	/*
	 * When @wait we can deadlock when we interrupt between llist_add() and
	 * arch_send_call_function_ipi*(); when !@wait we can deadlock due to
	 * csd_lock() on because the interrupt context uses the same csd
	 * storage.
	 */
	WARN_ON_ONCE(!in_task());

	csd = &csd_stack;
	if (!wait) {
		csd = this_cpu_ptr(&csd_data);
		csd_lock(csd);
	}

	err = generic_exec_single(cpu, csd, func, info);

	if (wait)
		csd_lock_wait(csd);

	put_cpu();

	return err;
}
EXPORT_SYMBOL(smp_call_function_single);

/**
 * smp_call_function_single_async(): Run an asynchronous function on a
 * 			         specific CPU.
 * @cpu: The CPU to run on.
 * @csd: Pre-allocated and setup data structure
 *
 * Like smp_call_function_single(), but the call is asynchonous and
 * can thus be done from contexts with disabled interrupts.
 *
 * The caller passes his own pre-allocated data structure
 * (ie: embedded in an object) and is responsible for synchronizing it
 * such that the IPIs performed on the @csd are strictly serialized.
 *
 * If the function is called with one csd which has not yet been
 * processed by previous call to smp_call_function_single_async(), the
 * function will return immediately with -EBUSY showing that the csd
 * object is still in progress.
 *
 * NOTE: Be careful, there is unfortunately no current debugging facility to
 * validate the correctness of this serialization.
 */
int smp_call_function_single_async(int cpu, call_single_data_t *csd)
{
	int err = 0;

	preempt_disable();

	if (csd->flags & CSD_FLAG_LOCK) {
		err = -EBUSY;
		goto out;
	}

	csd->flags = CSD_FLAG_LOCK;
	smp_wmb();

	err = generic_exec_single(cpu, csd, csd->func, csd->info);

out:
	preempt_enable();

	return err;
}
EXPORT_SYMBOL_GPL(smp_call_function_single_async);

/*
 * smp_call_function_any - Run a function on any of the given cpus
 * @mask: The mask of cpus it can run on.
 * @func: The function to run. This must be fast and non-blocking.
 * @info: An arbitrary pointer to pass to the function.
 * @wait: If true, wait until function has completed.
 *
 * Returns 0 on success, else a negative status code (if no cpus were online).
 *
 * Selection preference:
 *	1) current cpu if in @mask
 *	2) any cpu of current node if in @mask
 *	3) any other online cpu in @mask
 */
int smp_call_function_any(const struct cpumask *mask,
			  smp_call_func_t func, void *info, int wait)
{
	unsigned int cpu;
	const struct cpumask *nodemask;
	int ret;

	/* Try for same CPU (cheapest) */
	cpu = get_cpu();
	if (cpumask_test_cpu(cpu, mask))
		goto call;

	/* Try for same node. */
	nodemask = cpumask_of_node(cpu_to_node(cpu));
	for (cpu = cpumask_first_and(nodemask, mask); cpu < nr_cpu_ids;
	     cpu = cpumask_next_and(cpu, nodemask, mask)) {
		if (cpu_online(cpu))
			goto call;
	}

	/* Any online will do: smp_call_function_single handles nr_cpu_ids. */
	cpu = cpumask_any_and(mask, cpu_online_mask);
call:
	ret = smp_call_function_single(cpu, func, info, wait);
	put_cpu();
	return ret;
}
EXPORT_SYMBOL_GPL(smp_call_function_any);

static void smp_call_function_many_cond(const struct cpumask *mask,
					smp_call_func_t func, void *info,
					bool wait, smp_cond_func_t cond_func)
{
	struct call_function_data *cfd;
	int cpu, next_cpu, this_cpu = smp_processor_id();

	/*
	 * Can deadlock when called with interrupts disabled.
	 * We allow cpu's that are not yet online though, as no one else can
	 * send smp call function interrupt to this cpu and as such deadlocks
	 * can't happen.
	 */
	WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
		     && !oops_in_progress && !early_boot_irqs_disabled);

	/*
	 * When @wait we can deadlock when we interrupt between llist_add() and
	 * arch_send_call_function_ipi*(); when !@wait we can deadlock due to
	 * csd_lock() on because the interrupt context uses the same csd
	 * storage.
	 */
	WARN_ON_ONCE(!in_task());

	/* Try to fastpath.  So, what's a CPU they want? Ignoring this one. */
	cpu = cpumask_first_and(mask, cpu_online_mask);
	if (cpu == this_cpu)
		cpu = cpumask_next_and(cpu, mask, cpu_online_mask);

	/* No online cpus?  We're done. */
	if (cpu >= nr_cpu_ids)
		return;

	/* Do we have another CPU which isn't us? */
	next_cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
	if (next_cpu == this_cpu)
		next_cpu = cpumask_next_and(next_cpu, mask, cpu_online_mask);

	/* Fastpath: do that cpu by itself. */
	if (next_cpu >= nr_cpu_ids) {
		if (!cond_func || cond_func(cpu, info))
			smp_call_function_single(cpu, func, info, wait);
		return;
	}

	cfd = this_cpu_ptr(&cfd_data);

	cpumask_and(cfd->cpumask, mask, cpu_online_mask);
	__cpumask_clear_cpu(this_cpu, cfd->cpumask);

	/* Some callers race with other cpus changing the passed mask */
	if (unlikely(!cpumask_weight(cfd->cpumask)))
		return;

	cpumask_clear(cfd->cpumask_ipi);
	for_each_cpu(cpu, cfd->cpumask) {
		call_single_data_t *csd = per_cpu_ptr(cfd->csd, cpu);

		if (cond_func && !cond_func(cpu, info))
			continue;

		csd_lock(csd);
		if (wait)
			csd->flags |= CSD_FLAG_SYNCHRONOUS;
		csd->func = func;
		csd->info = info;
		if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu)))
			__cpumask_set_cpu(cpu, cfd->cpumask_ipi);
	}

	/* Send a message to all CPUs in the map */
	arch_send_call_function_ipi_mask(cfd->cpumask_ipi);

	if (wait) {
		for_each_cpu(cpu, cfd->cpumask) {
			call_single_data_t *csd;

			csd = per_cpu_ptr(cfd->csd, cpu);
			csd_lock_wait(csd);
		}
	}
}

/**
 * smp_call_function_many(): Run a function on a set of other CPUs.
 * @mask: The set of cpus to run on (only runs on online subset).
 * @func: The function to run. This must be fast and non-blocking.
 * @info: An arbitrary pointer to pass to the function.
 * @wait: If true, wait (atomically) until function has completed
 *        on other CPUs.
 *
 * If @wait is true, then returns once @func has returned.
 *
 * You must not call this function with disabled interrupts or from a
 * hardware interrupt handler or from a bottom half handler. Preemption
 * must be disabled when calling this function.
 */
void smp_call_function_many(const struct cpumask *mask,
			    smp_call_func_t func, void *info, bool wait)
{
	smp_call_function_many_cond(mask, func, info, wait, NULL);
}
EXPORT_SYMBOL(smp_call_function_many);

/**
 * smp_call_function(): Run a function on all other CPUs.
 * @func: The function to run. This must be fast and non-blocking.
 * @info: An arbitrary pointer to pass to the function.
 * @wait: If true, wait (atomically) until function has completed
 *        on other CPUs.
 *
 * Returns 0.
 *
 * If @wait is true, then returns once @func has returned; otherwise
 * it returns just before the target cpu calls @func.
 *
 * You must not call this function with disabled interrupts or from a
 * hardware interrupt handler or from a bottom half handler.
 */
void smp_call_function(smp_call_func_t func, void *info, int wait)
{
	preempt_disable();
	smp_call_function_many(cpu_online_mask, func, info, wait);
	preempt_enable();
}
EXPORT_SYMBOL(smp_call_function);

/* Setup configured maximum number of CPUs to activate */
unsigned int setup_max_cpus = NR_CPUS;
EXPORT_SYMBOL(setup_max_cpus);


/*
 * Setup routine for controlling SMP activation
 *
 * Command-line option of "nosmp" or "maxcpus=0" will disable SMP
 * activation entirely (the MPS table probe still happens, though).
 *
 * Command-line option of "maxcpus=<NUM>", where <NUM> is an integer
 * greater than 0, limits the maximum number of CPUs activated in
 * SMP mode to <NUM>.
 */

void __weak arch_disable_smp_support(void) { }

static int __init nosmp(char *str)
{
	setup_max_cpus = 0;
	arch_disable_smp_support();

	return 0;
}

early_param("nosmp", nosmp);

/* this is hard limit */
static int __init nrcpus(char *str)
{
	int nr_cpus;

	get_option(&str, &nr_cpus);
	if (nr_cpus > 0 && nr_cpus < nr_cpu_ids)
		nr_cpu_ids = nr_cpus;

	return 0;
}

early_param("nr_cpus", nrcpus);

static int __init maxcpus(char *str)
{
	get_option(&str, &setup_max_cpus);
	if (setup_max_cpus == 0)
		arch_disable_smp_support();

	return 0;
}

early_param("maxcpus", maxcpus);

/* Setup number of possible processor ids */
unsigned int nr_cpu_ids __read_mostly = NR_CPUS;
EXPORT_SYMBOL(nr_cpu_ids);

/* An arch may set nr_cpu_ids earlier if needed, so this would be redundant */
void __init setup_nr_cpu_ids(void)
{
	nr_cpu_ids = find_last_bit(cpumask_bits(cpu_possible_mask),NR_CPUS) + 1;
}

/* Called by boot processor to activate the rest. */
void __init smp_init(void)
{
	int num_nodes, num_cpus;

	idle_threads_init();
	cpuhp_threads_init();

	pr_info("Bringing up secondary CPUs ...\n");

	bringup_nonboot_cpus(setup_max_cpus);

	num_nodes = num_online_nodes();
	num_cpus  = num_online_cpus();
	pr_info("Brought up %d node%s, %d CPU%s\n",
		num_nodes, (num_nodes > 1 ? "s" : ""),
		num_cpus,  (num_cpus  > 1 ? "s" : ""));

	/* Any cleanup work */
	smp_cpus_done(setup_max_cpus);
}

/*
 * Call a function on all processors.  May be used during early boot while
 * early_boot_irqs_disabled is set.  Use local_irq_save/restore() instead
 * of local_irq_disable/enable().
 */
void on_each_cpu(void (*func) (void *info), void *info, int wait)
{
	unsigned long flags;

	preempt_disable();
	smp_call_function(func, info, wait);
	local_irq_save(flags);
	func(info);
	local_irq_restore(flags);
	preempt_enable();
}
EXPORT_SYMBOL(on_each_cpu);

/**
 * on_each_cpu_mask(): Run a function on processors specified by
 * cpumask, which may include the local processor.
 * @mask: The set of cpus to run on (only runs on online subset).
 * @func: The function to run. This must be fast and non-blocking.
 * @info: An arbitrary pointer to pass to the function.
 * @wait: If true, wait (atomically) until function has completed
 *        on other CPUs.
 *
 * If @wait is true, then returns once @func has returned.
 *
 * You must not call this function with disabled interrupts or from a
 * hardware interrupt handler or from a bottom half handler.  The
 * exception is that it may be used during early boot while
 * early_boot_irqs_disabled is set.
 */
void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func,
			void *info, bool wait)
{
	int cpu = get_cpu();

	smp_call_function_many(mask, func, info, wait);
	if (cpumask_test_cpu(cpu, mask)) {
		unsigned long flags;
		local_irq_save(flags);
		func(info);
		local_irq_restore(flags);
	}
	put_cpu();
}
EXPORT_SYMBOL(on_each_cpu_mask);

/*
 * on_each_cpu_cond(): Call a function on each processor for which
 * the supplied function cond_func returns true, optionally waiting
 * for all the required CPUs to finish. This may include the local
 * processor.
 * @cond_func:	A callback function that is passed a cpu id and
 *		the the info parameter. The function is called
 *		with preemption disabled. The function should
 *		return a blooean value indicating whether to IPI
 *		the specified CPU.
 * @func:	The function to run on all applicable CPUs.
 *		This must be fast and non-blocking.
 * @info:	An arbitrary pointer to pass to both functions.
 * @wait:	If true, wait (atomically) until function has
 *		completed on other CPUs.
 *
 * Preemption is disabled to protect against CPUs going offline but not online.
 * CPUs going online during the call will not be seen or sent an IPI.
 *
 * You must not call this function with disabled interrupts or
 * from a hardware interrupt handler or from a bottom half handler.
 */
void on_each_cpu_cond_mask(smp_cond_func_t cond_func, smp_call_func_t func,
			   void *info, bool wait, const struct cpumask *mask)
{
	int cpu = get_cpu();

	smp_call_function_many_cond(mask, func, info, wait, cond_func);
	if (cpumask_test_cpu(cpu, mask) && cond_func(cpu, info)) {
		unsigned long flags;

		local_irq_save(flags);
		func(info);
		local_irq_restore(flags);
	}
	put_cpu();
}
EXPORT_SYMBOL(on_each_cpu_cond_mask);

void on_each_cpu_cond(smp_cond_func_t cond_func, smp_call_func_t func,
		      void *info, bool wait)
{
	on_each_cpu_cond_mask(cond_func, func, info, wait, cpu_online_mask);
}
EXPORT_SYMBOL(on_each_cpu_cond);

static void do_nothing(void *unused)
{
}

/**
 * kick_all_cpus_sync - Force all cpus out of idle
 *
 * Used to synchronize the update of pm_idle function pointer. It's
 * called after the pointer is updated and returns after the dummy
 * callback function has been executed on all cpus. The execution of
 * the function can only happen on the remote cpus after they have
 * left the idle function which had been called via pm_idle function
 * pointer. So it's guaranteed that nothing uses the previous pointer
 * anymore.
 */
void kick_all_cpus_sync(void)
{
	/* Make sure the change is visible before we kick the cpus */
	smp_mb();
	smp_call_function(do_nothing, NULL, 1);
}
EXPORT_SYMBOL_GPL(kick_all_cpus_sync);

/**
 * wake_up_all_idle_cpus - break all cpus out of idle
 * wake_up_all_idle_cpus try to break all cpus which is in idle state even
 * including idle polling cpus, for non-idle cpus, we will do nothing
 * for them.
 */
void wake_up_all_idle_cpus(void)
{
	int cpu;

	preempt_disable();
	for_each_online_cpu(cpu) {
		if (cpu == smp_processor_id())
			continue;

		wake_up_if_idle(cpu);
	}
	preempt_enable();
}
EXPORT_SYMBOL_GPL(wake_up_all_idle_cpus);

/**
 * smp_call_on_cpu - Call a function on a specific cpu
 *
 * Used to call a function on a specific cpu and wait for it to return.
 * Optionally make sure the call is done on a specified physical cpu via vcpu
 * pinning in order to support virtualized environments.
 */
struct smp_call_on_cpu_struct {
	struct work_struct	work;
	struct completion	done;
	int			(*func)(void *);
	void			*data;
	int			ret;
	int			cpu;
};

static void smp_call_on_cpu_callback(struct work_struct *work)
{
	struct smp_call_on_cpu_struct *sscs;

	sscs = container_of(work, struct smp_call_on_cpu_struct, work);
	if (sscs->cpu >= 0)
		hypervisor_pin_vcpu(sscs->cpu);
	sscs->ret = sscs->func(sscs->data);
	if (sscs->cpu >= 0)
		hypervisor_pin_vcpu(-1);

	complete(&sscs->done);
}

int smp_call_on_cpu(unsigned int cpu, int (*func)(void *), void *par, bool phys)
{
	struct smp_call_on_cpu_struct sscs = {
		.done = COMPLETION_INITIALIZER_ONSTACK(sscs.done),
		.func = func,
		.data = par,
		.cpu  = phys ? cpu : -1,
	};

	INIT_WORK_ONSTACK(&sscs.work, smp_call_on_cpu_callback);

	if (cpu >= nr_cpu_ids || !cpu_online(cpu))
		return -ENXIO;

	queue_work_on(cpu, system_wq, &sscs.work);
	wait_for_completion(&sscs.done);

	return sscs.ret;
}
EXPORT_SYMBOL_GPL(smp_call_on_cpu);