xref: /openbmc/linux/kernel/time/tick-broadcast.c (revision b9d60493)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * This file contains functions which emulate a local clock-event
4  * device via a broadcast event source.
5  *
6  * Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
7  * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
8  * Copyright(C) 2006-2007, Timesys Corp., Thomas Gleixner
9  */
10 #include <linux/cpu.h>
11 #include <linux/err.h>
12 #include <linux/hrtimer.h>
13 #include <linux/interrupt.h>
14 #include <linux/percpu.h>
15 #include <linux/profile.h>
16 #include <linux/sched.h>
17 #include <linux/smp.h>
18 #include <linux/module.h>
19 
20 #include "tick-internal.h"
21 
22 /*
23  * Broadcast support for broken x86 hardware, where the local apic
24  * timer stops in C3 state.
25  */
26 
27 static struct tick_device tick_broadcast_device;
28 static cpumask_var_t tick_broadcast_mask __cpumask_var_read_mostly;
29 static cpumask_var_t tick_broadcast_on __cpumask_var_read_mostly;
30 static cpumask_var_t tmpmask __cpumask_var_read_mostly;
31 static int tick_broadcast_forced;
32 
33 static __cacheline_aligned_in_smp DEFINE_RAW_SPINLOCK(tick_broadcast_lock);
34 
35 #ifdef CONFIG_TICK_ONESHOT
36 static DEFINE_PER_CPU(struct clock_event_device *, tick_oneshot_wakeup_device);
37 
38 static void tick_broadcast_setup_oneshot(struct clock_event_device *bc, bool from_periodic);
39 static void tick_broadcast_clear_oneshot(int cpu);
40 static void tick_resume_broadcast_oneshot(struct clock_event_device *bc);
41 # ifdef CONFIG_HOTPLUG_CPU
42 static void tick_broadcast_oneshot_offline(unsigned int cpu);
43 # endif
44 #else
45 static inline void
tick_broadcast_setup_oneshot(struct clock_event_device * bc,bool from_periodic)46 tick_broadcast_setup_oneshot(struct clock_event_device *bc, bool from_periodic) { BUG(); }
tick_broadcast_clear_oneshot(int cpu)47 static inline void tick_broadcast_clear_oneshot(int cpu) { }
tick_resume_broadcast_oneshot(struct clock_event_device * bc)48 static inline void tick_resume_broadcast_oneshot(struct clock_event_device *bc) { }
49 # ifdef CONFIG_HOTPLUG_CPU
tick_broadcast_oneshot_offline(unsigned int cpu)50 static inline void tick_broadcast_oneshot_offline(unsigned int cpu) { }
51 # endif
52 #endif
53 
54 /*
55  * Debugging: see timer_list.c
56  */
tick_get_broadcast_device(void)57 struct tick_device *tick_get_broadcast_device(void)
58 {
59 	return &tick_broadcast_device;
60 }
61 
tick_get_broadcast_mask(void)62 struct cpumask *tick_get_broadcast_mask(void)
63 {
64 	return tick_broadcast_mask;
65 }
66 
67 static struct clock_event_device *tick_get_oneshot_wakeup_device(int cpu);
68 
tick_get_wakeup_device(int cpu)69 const struct clock_event_device *tick_get_wakeup_device(int cpu)
70 {
71 	return tick_get_oneshot_wakeup_device(cpu);
72 }
73 
74 /*
75  * Start the device in periodic mode
76  */
tick_broadcast_start_periodic(struct clock_event_device * bc)77 static void tick_broadcast_start_periodic(struct clock_event_device *bc)
78 {
79 	if (bc)
80 		tick_setup_periodic(bc, 1);
81 }
82 
83 /*
84  * Check, if the device can be utilized as broadcast device:
85  */
tick_check_broadcast_device(struct clock_event_device * curdev,struct clock_event_device * newdev)86 static bool tick_check_broadcast_device(struct clock_event_device *curdev,
87 					struct clock_event_device *newdev)
88 {
89 	if ((newdev->features & CLOCK_EVT_FEAT_DUMMY) ||
90 	    (newdev->features & CLOCK_EVT_FEAT_PERCPU) ||
91 	    (newdev->features & CLOCK_EVT_FEAT_C3STOP))
92 		return false;
93 
94 	if (tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT &&
95 	    !(newdev->features & CLOCK_EVT_FEAT_ONESHOT))
96 		return false;
97 
98 	return !curdev || newdev->rating > curdev->rating;
99 }
100 
101 #ifdef CONFIG_TICK_ONESHOT
tick_get_oneshot_wakeup_device(int cpu)102 static struct clock_event_device *tick_get_oneshot_wakeup_device(int cpu)
103 {
104 	return per_cpu(tick_oneshot_wakeup_device, cpu);
105 }
106 
tick_oneshot_wakeup_handler(struct clock_event_device * wd)107 static void tick_oneshot_wakeup_handler(struct clock_event_device *wd)
108 {
109 	/*
110 	 * If we woke up early and the tick was reprogrammed in the
111 	 * meantime then this may be spurious but harmless.
112 	 */
113 	tick_receive_broadcast();
114 }
115 
tick_set_oneshot_wakeup_device(struct clock_event_device * newdev,int cpu)116 static bool tick_set_oneshot_wakeup_device(struct clock_event_device *newdev,
117 					   int cpu)
118 {
119 	struct clock_event_device *curdev = tick_get_oneshot_wakeup_device(cpu);
120 
121 	if (!newdev)
122 		goto set_device;
123 
124 	if ((newdev->features & CLOCK_EVT_FEAT_DUMMY) ||
125 	    (newdev->features & CLOCK_EVT_FEAT_C3STOP))
126 		 return false;
127 
128 	if (!(newdev->features & CLOCK_EVT_FEAT_PERCPU) ||
129 	    !(newdev->features & CLOCK_EVT_FEAT_ONESHOT))
130 		return false;
131 
132 	if (!cpumask_equal(newdev->cpumask, cpumask_of(cpu)))
133 		return false;
134 
135 	if (curdev && newdev->rating <= curdev->rating)
136 		return false;
137 
138 	if (!try_module_get(newdev->owner))
139 		return false;
140 
141 	newdev->event_handler = tick_oneshot_wakeup_handler;
142 set_device:
143 	clockevents_exchange_device(curdev, newdev);
144 	per_cpu(tick_oneshot_wakeup_device, cpu) = newdev;
145 	return true;
146 }
147 #else
tick_get_oneshot_wakeup_device(int cpu)148 static struct clock_event_device *tick_get_oneshot_wakeup_device(int cpu)
149 {
150 	return NULL;
151 }
152 
tick_set_oneshot_wakeup_device(struct clock_event_device * newdev,int cpu)153 static bool tick_set_oneshot_wakeup_device(struct clock_event_device *newdev,
154 					   int cpu)
155 {
156 	return false;
157 }
158 #endif
159 
160 /*
161  * Conditionally install/replace broadcast device
162  */
tick_install_broadcast_device(struct clock_event_device * dev,int cpu)163 void tick_install_broadcast_device(struct clock_event_device *dev, int cpu)
164 {
165 	struct clock_event_device *cur = tick_broadcast_device.evtdev;
166 
167 	if (tick_set_oneshot_wakeup_device(dev, cpu))
168 		return;
169 
170 	if (!tick_check_broadcast_device(cur, dev))
171 		return;
172 
173 	if (!try_module_get(dev->owner))
174 		return;
175 
176 	clockevents_exchange_device(cur, dev);
177 	if (cur)
178 		cur->event_handler = clockevents_handle_noop;
179 	tick_broadcast_device.evtdev = dev;
180 	if (!cpumask_empty(tick_broadcast_mask))
181 		tick_broadcast_start_periodic(dev);
182 
183 	if (!(dev->features & CLOCK_EVT_FEAT_ONESHOT))
184 		return;
185 
186 	/*
187 	 * If the system already runs in oneshot mode, switch the newly
188 	 * registered broadcast device to oneshot mode explicitly.
189 	 */
190 	if (tick_broadcast_oneshot_active()) {
191 		tick_broadcast_switch_to_oneshot();
192 		return;
193 	}
194 
195 	/*
196 	 * Inform all cpus about this. We might be in a situation
197 	 * where we did not switch to oneshot mode because the per cpu
198 	 * devices are affected by CLOCK_EVT_FEAT_C3STOP and the lack
199 	 * of a oneshot capable broadcast device. Without that
200 	 * notification the systems stays stuck in periodic mode
201 	 * forever.
202 	 */
203 	tick_clock_notify();
204 }
205 
206 /*
207  * Check, if the device is the broadcast device
208  */
tick_is_broadcast_device(struct clock_event_device * dev)209 int tick_is_broadcast_device(struct clock_event_device *dev)
210 {
211 	return (dev && tick_broadcast_device.evtdev == dev);
212 }
213 
tick_broadcast_update_freq(struct clock_event_device * dev,u32 freq)214 int tick_broadcast_update_freq(struct clock_event_device *dev, u32 freq)
215 {
216 	int ret = -ENODEV;
217 
218 	if (tick_is_broadcast_device(dev)) {
219 		raw_spin_lock(&tick_broadcast_lock);
220 		ret = __clockevents_update_freq(dev, freq);
221 		raw_spin_unlock(&tick_broadcast_lock);
222 	}
223 	return ret;
224 }
225 
226 
err_broadcast(const struct cpumask * mask)227 static void err_broadcast(const struct cpumask *mask)
228 {
229 	pr_crit_once("Failed to broadcast timer tick. Some CPUs may be unresponsive.\n");
230 }
231 
tick_device_setup_broadcast_func(struct clock_event_device * dev)232 static void tick_device_setup_broadcast_func(struct clock_event_device *dev)
233 {
234 	if (!dev->broadcast)
235 		dev->broadcast = tick_broadcast;
236 	if (!dev->broadcast) {
237 		pr_warn_once("%s depends on broadcast, but no broadcast function available\n",
238 			     dev->name);
239 		dev->broadcast = err_broadcast;
240 	}
241 }
242 
243 /*
244  * Check, if the device is dysfunctional and a placeholder, which
245  * needs to be handled by the broadcast device.
246  */
tick_device_uses_broadcast(struct clock_event_device * dev,int cpu)247 int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu)
248 {
249 	struct clock_event_device *bc = tick_broadcast_device.evtdev;
250 	unsigned long flags;
251 	int ret = 0;
252 
253 	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
254 
255 	/*
256 	 * Devices might be registered with both periodic and oneshot
257 	 * mode disabled. This signals, that the device needs to be
258 	 * operated from the broadcast device and is a placeholder for
259 	 * the cpu local device.
260 	 */
261 	if (!tick_device_is_functional(dev)) {
262 		dev->event_handler = tick_handle_periodic;
263 		tick_device_setup_broadcast_func(dev);
264 		cpumask_set_cpu(cpu, tick_broadcast_mask);
265 		if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
266 			tick_broadcast_start_periodic(bc);
267 		else
268 			tick_broadcast_setup_oneshot(bc, false);
269 		ret = 1;
270 	} else {
271 		/*
272 		 * Clear the broadcast bit for this cpu if the
273 		 * device is not power state affected.
274 		 */
275 		if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))
276 			cpumask_clear_cpu(cpu, tick_broadcast_mask);
277 		else
278 			tick_device_setup_broadcast_func(dev);
279 
280 		/*
281 		 * Clear the broadcast bit if the CPU is not in
282 		 * periodic broadcast on state.
283 		 */
284 		if (!cpumask_test_cpu(cpu, tick_broadcast_on))
285 			cpumask_clear_cpu(cpu, tick_broadcast_mask);
286 
287 		switch (tick_broadcast_device.mode) {
288 		case TICKDEV_MODE_ONESHOT:
289 			/*
290 			 * If the system is in oneshot mode we can
291 			 * unconditionally clear the oneshot mask bit,
292 			 * because the CPU is running and therefore
293 			 * not in an idle state which causes the power
294 			 * state affected device to stop. Let the
295 			 * caller initialize the device.
296 			 */
297 			tick_broadcast_clear_oneshot(cpu);
298 			ret = 0;
299 			break;
300 
301 		case TICKDEV_MODE_PERIODIC:
302 			/*
303 			 * If the system is in periodic mode, check
304 			 * whether the broadcast device can be
305 			 * switched off now.
306 			 */
307 			if (cpumask_empty(tick_broadcast_mask) && bc)
308 				clockevents_shutdown(bc);
309 			/*
310 			 * If we kept the cpu in the broadcast mask,
311 			 * tell the caller to leave the per cpu device
312 			 * in shutdown state. The periodic interrupt
313 			 * is delivered by the broadcast device, if
314 			 * the broadcast device exists and is not
315 			 * hrtimer based.
316 			 */
317 			if (bc && !(bc->features & CLOCK_EVT_FEAT_HRTIMER))
318 				ret = cpumask_test_cpu(cpu, tick_broadcast_mask);
319 			break;
320 		default:
321 			break;
322 		}
323 	}
324 	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
325 	return ret;
326 }
327 
tick_receive_broadcast(void)328 int tick_receive_broadcast(void)
329 {
330 	struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
331 	struct clock_event_device *evt = td->evtdev;
332 
333 	if (!evt)
334 		return -ENODEV;
335 
336 	if (!evt->event_handler)
337 		return -EINVAL;
338 
339 	evt->event_handler(evt);
340 	return 0;
341 }
342 
343 /*
344  * Broadcast the event to the cpus, which are set in the mask (mangled).
345  */
tick_do_broadcast(struct cpumask * mask)346 static bool tick_do_broadcast(struct cpumask *mask)
347 {
348 	int cpu = smp_processor_id();
349 	struct tick_device *td;
350 	bool local = false;
351 
352 	/*
353 	 * Check, if the current cpu is in the mask
354 	 */
355 	if (cpumask_test_cpu(cpu, mask)) {
356 		struct clock_event_device *bc = tick_broadcast_device.evtdev;
357 
358 		cpumask_clear_cpu(cpu, mask);
359 		/*
360 		 * We only run the local handler, if the broadcast
361 		 * device is not hrtimer based. Otherwise we run into
362 		 * a hrtimer recursion.
363 		 *
364 		 * local timer_interrupt()
365 		 *   local_handler()
366 		 *     expire_hrtimers()
367 		 *       bc_handler()
368 		 *         local_handler()
369 		 *	     expire_hrtimers()
370 		 */
371 		local = !(bc->features & CLOCK_EVT_FEAT_HRTIMER);
372 	}
373 
374 	if (!cpumask_empty(mask)) {
375 		/*
376 		 * It might be necessary to actually check whether the devices
377 		 * have different broadcast functions. For now, just use the
378 		 * one of the first device. This works as long as we have this
379 		 * misfeature only on x86 (lapic)
380 		 */
381 		td = &per_cpu(tick_cpu_device, cpumask_first(mask));
382 		td->evtdev->broadcast(mask);
383 	}
384 	return local;
385 }
386 
387 /*
388  * Periodic broadcast:
389  * - invoke the broadcast handlers
390  */
tick_do_periodic_broadcast(void)391 static bool tick_do_periodic_broadcast(void)
392 {
393 	cpumask_and(tmpmask, cpu_online_mask, tick_broadcast_mask);
394 	return tick_do_broadcast(tmpmask);
395 }
396 
397 /*
398  * Event handler for periodic broadcast ticks
399  */
tick_handle_periodic_broadcast(struct clock_event_device * dev)400 static void tick_handle_periodic_broadcast(struct clock_event_device *dev)
401 {
402 	struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
403 	bool bc_local;
404 
405 	raw_spin_lock(&tick_broadcast_lock);
406 
407 	/* Handle spurious interrupts gracefully */
408 	if (clockevent_state_shutdown(tick_broadcast_device.evtdev)) {
409 		raw_spin_unlock(&tick_broadcast_lock);
410 		return;
411 	}
412 
413 	bc_local = tick_do_periodic_broadcast();
414 
415 	if (clockevent_state_oneshot(dev)) {
416 		ktime_t next = ktime_add_ns(dev->next_event, TICK_NSEC);
417 
418 		clockevents_program_event(dev, next, true);
419 	}
420 	raw_spin_unlock(&tick_broadcast_lock);
421 
422 	/*
423 	 * We run the handler of the local cpu after dropping
424 	 * tick_broadcast_lock because the handler might deadlock when
425 	 * trying to switch to oneshot mode.
426 	 */
427 	if (bc_local)
428 		td->evtdev->event_handler(td->evtdev);
429 }
430 
431 /**
432  * tick_broadcast_control - Enable/disable or force broadcast mode
433  * @mode:	The selected broadcast mode
434  *
435  * Called when the system enters a state where affected tick devices
436  * might stop. Note: TICK_BROADCAST_FORCE cannot be undone.
437  */
tick_broadcast_control(enum tick_broadcast_mode mode)438 void tick_broadcast_control(enum tick_broadcast_mode mode)
439 {
440 	struct clock_event_device *bc, *dev;
441 	struct tick_device *td;
442 	int cpu, bc_stopped;
443 	unsigned long flags;
444 
445 	/* Protects also the local clockevent device. */
446 	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
447 	td = this_cpu_ptr(&tick_cpu_device);
448 	dev = td->evtdev;
449 
450 	/*
451 	 * Is the device not affected by the powerstate ?
452 	 */
453 	if (!dev || !(dev->features & CLOCK_EVT_FEAT_C3STOP))
454 		goto out;
455 
456 	if (!tick_device_is_functional(dev))
457 		goto out;
458 
459 	cpu = smp_processor_id();
460 	bc = tick_broadcast_device.evtdev;
461 	bc_stopped = cpumask_empty(tick_broadcast_mask);
462 
463 	switch (mode) {
464 	case TICK_BROADCAST_FORCE:
465 		tick_broadcast_forced = 1;
466 		fallthrough;
467 	case TICK_BROADCAST_ON:
468 		cpumask_set_cpu(cpu, tick_broadcast_on);
469 		if (!cpumask_test_and_set_cpu(cpu, tick_broadcast_mask)) {
470 			/*
471 			 * Only shutdown the cpu local device, if:
472 			 *
473 			 * - the broadcast device exists
474 			 * - the broadcast device is not a hrtimer based one
475 			 * - the broadcast device is in periodic mode to
476 			 *   avoid a hiccup during switch to oneshot mode
477 			 */
478 			if (bc && !(bc->features & CLOCK_EVT_FEAT_HRTIMER) &&
479 			    tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
480 				clockevents_shutdown(dev);
481 		}
482 		break;
483 
484 	case TICK_BROADCAST_OFF:
485 		if (tick_broadcast_forced)
486 			break;
487 		cpumask_clear_cpu(cpu, tick_broadcast_on);
488 		if (cpumask_test_and_clear_cpu(cpu, tick_broadcast_mask)) {
489 			if (tick_broadcast_device.mode ==
490 			    TICKDEV_MODE_PERIODIC)
491 				tick_setup_periodic(dev, 0);
492 		}
493 		break;
494 	}
495 
496 	if (bc) {
497 		if (cpumask_empty(tick_broadcast_mask)) {
498 			if (!bc_stopped)
499 				clockevents_shutdown(bc);
500 		} else if (bc_stopped) {
501 			if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
502 				tick_broadcast_start_periodic(bc);
503 			else
504 				tick_broadcast_setup_oneshot(bc, false);
505 		}
506 	}
507 out:
508 	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
509 }
510 EXPORT_SYMBOL_GPL(tick_broadcast_control);
511 
512 /*
513  * Set the periodic handler depending on broadcast on/off
514  */
tick_set_periodic_handler(struct clock_event_device * dev,int broadcast)515 void tick_set_periodic_handler(struct clock_event_device *dev, int broadcast)
516 {
517 	if (!broadcast)
518 		dev->event_handler = tick_handle_periodic;
519 	else
520 		dev->event_handler = tick_handle_periodic_broadcast;
521 }
522 
523 #ifdef CONFIG_HOTPLUG_CPU
tick_shutdown_broadcast(void)524 static void tick_shutdown_broadcast(void)
525 {
526 	struct clock_event_device *bc = tick_broadcast_device.evtdev;
527 
528 	if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) {
529 		if (bc && cpumask_empty(tick_broadcast_mask))
530 			clockevents_shutdown(bc);
531 	}
532 }
533 
534 /*
535  * Remove a CPU from broadcasting
536  */
tick_broadcast_offline(unsigned int cpu)537 void tick_broadcast_offline(unsigned int cpu)
538 {
539 	raw_spin_lock(&tick_broadcast_lock);
540 	cpumask_clear_cpu(cpu, tick_broadcast_mask);
541 	cpumask_clear_cpu(cpu, tick_broadcast_on);
542 	tick_broadcast_oneshot_offline(cpu);
543 	tick_shutdown_broadcast();
544 	raw_spin_unlock(&tick_broadcast_lock);
545 }
546 
547 #endif
548 
tick_suspend_broadcast(void)549 void tick_suspend_broadcast(void)
550 {
551 	struct clock_event_device *bc;
552 	unsigned long flags;
553 
554 	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
555 
556 	bc = tick_broadcast_device.evtdev;
557 	if (bc)
558 		clockevents_shutdown(bc);
559 
560 	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
561 }
562 
563 /*
564  * This is called from tick_resume_local() on a resuming CPU. That's
565  * called from the core resume function, tick_unfreeze() and the magic XEN
566  * resume hackery.
567  *
568  * In none of these cases the broadcast device mode can change and the
569  * bit of the resuming CPU in the broadcast mask is safe as well.
570  */
tick_resume_check_broadcast(void)571 bool tick_resume_check_broadcast(void)
572 {
573 	if (tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT)
574 		return false;
575 	else
576 		return cpumask_test_cpu(smp_processor_id(), tick_broadcast_mask);
577 }
578 
tick_resume_broadcast(void)579 void tick_resume_broadcast(void)
580 {
581 	struct clock_event_device *bc;
582 	unsigned long flags;
583 
584 	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
585 
586 	bc = tick_broadcast_device.evtdev;
587 
588 	if (bc) {
589 		clockevents_tick_resume(bc);
590 
591 		switch (tick_broadcast_device.mode) {
592 		case TICKDEV_MODE_PERIODIC:
593 			if (!cpumask_empty(tick_broadcast_mask))
594 				tick_broadcast_start_periodic(bc);
595 			break;
596 		case TICKDEV_MODE_ONESHOT:
597 			if (!cpumask_empty(tick_broadcast_mask))
598 				tick_resume_broadcast_oneshot(bc);
599 			break;
600 		}
601 	}
602 	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
603 }
604 
605 #ifdef CONFIG_TICK_ONESHOT
606 
607 static cpumask_var_t tick_broadcast_oneshot_mask __cpumask_var_read_mostly;
608 static cpumask_var_t tick_broadcast_pending_mask __cpumask_var_read_mostly;
609 static cpumask_var_t tick_broadcast_force_mask __cpumask_var_read_mostly;
610 
611 /*
612  * Exposed for debugging: see timer_list.c
613  */
tick_get_broadcast_oneshot_mask(void)614 struct cpumask *tick_get_broadcast_oneshot_mask(void)
615 {
616 	return tick_broadcast_oneshot_mask;
617 }
618 
619 /*
620  * Called before going idle with interrupts disabled. Checks whether a
621  * broadcast event from the other core is about to happen. We detected
622  * that in tick_broadcast_oneshot_control(). The callsite can use this
623  * to avoid a deep idle transition as we are about to get the
624  * broadcast IPI right away.
625  */
tick_check_broadcast_expired(void)626 noinstr int tick_check_broadcast_expired(void)
627 {
628 #ifdef _ASM_GENERIC_BITOPS_INSTRUMENTED_NON_ATOMIC_H
629 	return arch_test_bit(smp_processor_id(), cpumask_bits(tick_broadcast_force_mask));
630 #else
631 	return cpumask_test_cpu(smp_processor_id(), tick_broadcast_force_mask);
632 #endif
633 }
634 
635 /*
636  * Set broadcast interrupt affinity
637  */
tick_broadcast_set_affinity(struct clock_event_device * bc,const struct cpumask * cpumask)638 static void tick_broadcast_set_affinity(struct clock_event_device *bc,
639 					const struct cpumask *cpumask)
640 {
641 	if (!(bc->features & CLOCK_EVT_FEAT_DYNIRQ))
642 		return;
643 
644 	if (cpumask_equal(bc->cpumask, cpumask))
645 		return;
646 
647 	bc->cpumask = cpumask;
648 	irq_set_affinity(bc->irq, bc->cpumask);
649 }
650 
tick_broadcast_set_event(struct clock_event_device * bc,int cpu,ktime_t expires)651 static void tick_broadcast_set_event(struct clock_event_device *bc, int cpu,
652 				     ktime_t expires)
653 {
654 	if (!clockevent_state_oneshot(bc))
655 		clockevents_switch_state(bc, CLOCK_EVT_STATE_ONESHOT);
656 
657 	clockevents_program_event(bc, expires, 1);
658 	tick_broadcast_set_affinity(bc, cpumask_of(cpu));
659 }
660 
tick_resume_broadcast_oneshot(struct clock_event_device * bc)661 static void tick_resume_broadcast_oneshot(struct clock_event_device *bc)
662 {
663 	clockevents_switch_state(bc, CLOCK_EVT_STATE_ONESHOT);
664 }
665 
666 /*
667  * Called from irq_enter() when idle was interrupted to reenable the
668  * per cpu device.
669  */
tick_check_oneshot_broadcast_this_cpu(void)670 void tick_check_oneshot_broadcast_this_cpu(void)
671 {
672 	if (cpumask_test_cpu(smp_processor_id(), tick_broadcast_oneshot_mask)) {
673 		struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
674 
675 		/*
676 		 * We might be in the middle of switching over from
677 		 * periodic to oneshot. If the CPU has not yet
678 		 * switched over, leave the device alone.
679 		 */
680 		if (td->mode == TICKDEV_MODE_ONESHOT) {
681 			clockevents_switch_state(td->evtdev,
682 					      CLOCK_EVT_STATE_ONESHOT);
683 		}
684 	}
685 }
686 
687 /*
688  * Handle oneshot mode broadcasting
689  */
tick_handle_oneshot_broadcast(struct clock_event_device * dev)690 static void tick_handle_oneshot_broadcast(struct clock_event_device *dev)
691 {
692 	struct tick_device *td;
693 	ktime_t now, next_event;
694 	int cpu, next_cpu = 0;
695 	bool bc_local;
696 
697 	raw_spin_lock(&tick_broadcast_lock);
698 	dev->next_event = KTIME_MAX;
699 	next_event = KTIME_MAX;
700 	cpumask_clear(tmpmask);
701 	now = ktime_get();
702 	/* Find all expired events */
703 	for_each_cpu(cpu, tick_broadcast_oneshot_mask) {
704 		/*
705 		 * Required for !SMP because for_each_cpu() reports
706 		 * unconditionally CPU0 as set on UP kernels.
707 		 */
708 		if (!IS_ENABLED(CONFIG_SMP) &&
709 		    cpumask_empty(tick_broadcast_oneshot_mask))
710 			break;
711 
712 		td = &per_cpu(tick_cpu_device, cpu);
713 		if (td->evtdev->next_event <= now) {
714 			cpumask_set_cpu(cpu, tmpmask);
715 			/*
716 			 * Mark the remote cpu in the pending mask, so
717 			 * it can avoid reprogramming the cpu local
718 			 * timer in tick_broadcast_oneshot_control().
719 			 */
720 			cpumask_set_cpu(cpu, tick_broadcast_pending_mask);
721 		} else if (td->evtdev->next_event < next_event) {
722 			next_event = td->evtdev->next_event;
723 			next_cpu = cpu;
724 		}
725 	}
726 
727 	/*
728 	 * Remove the current cpu from the pending mask. The event is
729 	 * delivered immediately in tick_do_broadcast() !
730 	 */
731 	cpumask_clear_cpu(smp_processor_id(), tick_broadcast_pending_mask);
732 
733 	/* Take care of enforced broadcast requests */
734 	cpumask_or(tmpmask, tmpmask, tick_broadcast_force_mask);
735 	cpumask_clear(tick_broadcast_force_mask);
736 
737 	/*
738 	 * Sanity check. Catch the case where we try to broadcast to
739 	 * offline cpus.
740 	 */
741 	if (WARN_ON_ONCE(!cpumask_subset(tmpmask, cpu_online_mask)))
742 		cpumask_and(tmpmask, tmpmask, cpu_online_mask);
743 
744 	/*
745 	 * Wakeup the cpus which have an expired event.
746 	 */
747 	bc_local = tick_do_broadcast(tmpmask);
748 
749 	/*
750 	 * Two reasons for reprogram:
751 	 *
752 	 * - The global event did not expire any CPU local
753 	 * events. This happens in dyntick mode, as the maximum PIT
754 	 * delta is quite small.
755 	 *
756 	 * - There are pending events on sleeping CPUs which were not
757 	 * in the event mask
758 	 */
759 	if (next_event != KTIME_MAX)
760 		tick_broadcast_set_event(dev, next_cpu, next_event);
761 
762 	raw_spin_unlock(&tick_broadcast_lock);
763 
764 	if (bc_local) {
765 		td = this_cpu_ptr(&tick_cpu_device);
766 		td->evtdev->event_handler(td->evtdev);
767 	}
768 }
769 
broadcast_needs_cpu(struct clock_event_device * bc,int cpu)770 static int broadcast_needs_cpu(struct clock_event_device *bc, int cpu)
771 {
772 	if (!(bc->features & CLOCK_EVT_FEAT_HRTIMER))
773 		return 0;
774 	if (bc->next_event == KTIME_MAX)
775 		return 0;
776 	return bc->bound_on == cpu ? -EBUSY : 0;
777 }
778 
broadcast_shutdown_local(struct clock_event_device * bc,struct clock_event_device * dev)779 static void broadcast_shutdown_local(struct clock_event_device *bc,
780 				     struct clock_event_device *dev)
781 {
782 	/*
783 	 * For hrtimer based broadcasting we cannot shutdown the cpu
784 	 * local device if our own event is the first one to expire or
785 	 * if we own the broadcast timer.
786 	 */
787 	if (bc->features & CLOCK_EVT_FEAT_HRTIMER) {
788 		if (broadcast_needs_cpu(bc, smp_processor_id()))
789 			return;
790 		if (dev->next_event < bc->next_event)
791 			return;
792 	}
793 	clockevents_switch_state(dev, CLOCK_EVT_STATE_SHUTDOWN);
794 }
795 
___tick_broadcast_oneshot_control(enum tick_broadcast_state state,struct tick_device * td,int cpu)796 static int ___tick_broadcast_oneshot_control(enum tick_broadcast_state state,
797 					     struct tick_device *td,
798 					     int cpu)
799 {
800 	struct clock_event_device *bc, *dev = td->evtdev;
801 	int ret = 0;
802 	ktime_t now;
803 
804 	raw_spin_lock(&tick_broadcast_lock);
805 	bc = tick_broadcast_device.evtdev;
806 
807 	if (state == TICK_BROADCAST_ENTER) {
808 		/*
809 		 * If the current CPU owns the hrtimer broadcast
810 		 * mechanism, it cannot go deep idle and we do not add
811 		 * the CPU to the broadcast mask. We don't have to go
812 		 * through the EXIT path as the local timer is not
813 		 * shutdown.
814 		 */
815 		ret = broadcast_needs_cpu(bc, cpu);
816 		if (ret)
817 			goto out;
818 
819 		/*
820 		 * If the broadcast device is in periodic mode, we
821 		 * return.
822 		 */
823 		if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) {
824 			/* If it is a hrtimer based broadcast, return busy */
825 			if (bc->features & CLOCK_EVT_FEAT_HRTIMER)
826 				ret = -EBUSY;
827 			goto out;
828 		}
829 
830 		if (!cpumask_test_and_set_cpu(cpu, tick_broadcast_oneshot_mask)) {
831 			WARN_ON_ONCE(cpumask_test_cpu(cpu, tick_broadcast_pending_mask));
832 
833 			/* Conditionally shut down the local timer. */
834 			broadcast_shutdown_local(bc, dev);
835 
836 			/*
837 			 * We only reprogram the broadcast timer if we
838 			 * did not mark ourself in the force mask and
839 			 * if the cpu local event is earlier than the
840 			 * broadcast event. If the current CPU is in
841 			 * the force mask, then we are going to be
842 			 * woken by the IPI right away; we return
843 			 * busy, so the CPU does not try to go deep
844 			 * idle.
845 			 */
846 			if (cpumask_test_cpu(cpu, tick_broadcast_force_mask)) {
847 				ret = -EBUSY;
848 			} else if (dev->next_event < bc->next_event) {
849 				tick_broadcast_set_event(bc, cpu, dev->next_event);
850 				/*
851 				 * In case of hrtimer broadcasts the
852 				 * programming might have moved the
853 				 * timer to this cpu. If yes, remove
854 				 * us from the broadcast mask and
855 				 * return busy.
856 				 */
857 				ret = broadcast_needs_cpu(bc, cpu);
858 				if (ret) {
859 					cpumask_clear_cpu(cpu,
860 						tick_broadcast_oneshot_mask);
861 				}
862 			}
863 		}
864 	} else {
865 		if (cpumask_test_and_clear_cpu(cpu, tick_broadcast_oneshot_mask)) {
866 			clockevents_switch_state(dev, CLOCK_EVT_STATE_ONESHOT);
867 			/*
868 			 * The cpu which was handling the broadcast
869 			 * timer marked this cpu in the broadcast
870 			 * pending mask and fired the broadcast
871 			 * IPI. So we are going to handle the expired
872 			 * event anyway via the broadcast IPI
873 			 * handler. No need to reprogram the timer
874 			 * with an already expired event.
875 			 */
876 			if (cpumask_test_and_clear_cpu(cpu,
877 				       tick_broadcast_pending_mask))
878 				goto out;
879 
880 			/*
881 			 * Bail out if there is no next event.
882 			 */
883 			if (dev->next_event == KTIME_MAX)
884 				goto out;
885 			/*
886 			 * If the pending bit is not set, then we are
887 			 * either the CPU handling the broadcast
888 			 * interrupt or we got woken by something else.
889 			 *
890 			 * We are no longer in the broadcast mask, so
891 			 * if the cpu local expiry time is already
892 			 * reached, we would reprogram the cpu local
893 			 * timer with an already expired event.
894 			 *
895 			 * This can lead to a ping-pong when we return
896 			 * to idle and therefore rearm the broadcast
897 			 * timer before the cpu local timer was able
898 			 * to fire. This happens because the forced
899 			 * reprogramming makes sure that the event
900 			 * will happen in the future and depending on
901 			 * the min_delta setting this might be far
902 			 * enough out that the ping-pong starts.
903 			 *
904 			 * If the cpu local next_event has expired
905 			 * then we know that the broadcast timer
906 			 * next_event has expired as well and
907 			 * broadcast is about to be handled. So we
908 			 * avoid reprogramming and enforce that the
909 			 * broadcast handler, which did not run yet,
910 			 * will invoke the cpu local handler.
911 			 *
912 			 * We cannot call the handler directly from
913 			 * here, because we might be in a NOHZ phase
914 			 * and we did not go through the irq_enter()
915 			 * nohz fixups.
916 			 */
917 			now = ktime_get();
918 			if (dev->next_event <= now) {
919 				cpumask_set_cpu(cpu, tick_broadcast_force_mask);
920 				goto out;
921 			}
922 			/*
923 			 * We got woken by something else. Reprogram
924 			 * the cpu local timer device.
925 			 */
926 			tick_program_event(dev->next_event, 1);
927 		}
928 	}
929 out:
930 	raw_spin_unlock(&tick_broadcast_lock);
931 	return ret;
932 }
933 
tick_oneshot_wakeup_control(enum tick_broadcast_state state,struct tick_device * td,int cpu)934 static int tick_oneshot_wakeup_control(enum tick_broadcast_state state,
935 				       struct tick_device *td,
936 				       int cpu)
937 {
938 	struct clock_event_device *dev, *wd;
939 
940 	dev = td->evtdev;
941 	if (td->mode != TICKDEV_MODE_ONESHOT)
942 		return -EINVAL;
943 
944 	wd = tick_get_oneshot_wakeup_device(cpu);
945 	if (!wd)
946 		return -ENODEV;
947 
948 	switch (state) {
949 	case TICK_BROADCAST_ENTER:
950 		clockevents_switch_state(dev, CLOCK_EVT_STATE_ONESHOT_STOPPED);
951 		clockevents_switch_state(wd, CLOCK_EVT_STATE_ONESHOT);
952 		clockevents_program_event(wd, dev->next_event, 1);
953 		break;
954 	case TICK_BROADCAST_EXIT:
955 		/* We may have transitioned to oneshot mode while idle */
956 		if (clockevent_get_state(wd) != CLOCK_EVT_STATE_ONESHOT)
957 			return -ENODEV;
958 	}
959 
960 	return 0;
961 }
962 
__tick_broadcast_oneshot_control(enum tick_broadcast_state state)963 int __tick_broadcast_oneshot_control(enum tick_broadcast_state state)
964 {
965 	struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
966 	int cpu = smp_processor_id();
967 
968 	if (!tick_oneshot_wakeup_control(state, td, cpu))
969 		return 0;
970 
971 	if (tick_broadcast_device.evtdev)
972 		return ___tick_broadcast_oneshot_control(state, td, cpu);
973 
974 	/*
975 	 * If there is no broadcast or wakeup device, tell the caller not
976 	 * to go into deep idle.
977 	 */
978 	return -EBUSY;
979 }
980 
981 /*
982  * Reset the one shot broadcast for a cpu
983  *
984  * Called with tick_broadcast_lock held
985  */
tick_broadcast_clear_oneshot(int cpu)986 static void tick_broadcast_clear_oneshot(int cpu)
987 {
988 	cpumask_clear_cpu(cpu, tick_broadcast_oneshot_mask);
989 	cpumask_clear_cpu(cpu, tick_broadcast_pending_mask);
990 }
991 
tick_broadcast_init_next_event(struct cpumask * mask,ktime_t expires)992 static void tick_broadcast_init_next_event(struct cpumask *mask,
993 					   ktime_t expires)
994 {
995 	struct tick_device *td;
996 	int cpu;
997 
998 	for_each_cpu(cpu, mask) {
999 		td = &per_cpu(tick_cpu_device, cpu);
1000 		if (td->evtdev)
1001 			td->evtdev->next_event = expires;
1002 	}
1003 }
1004 
tick_get_next_period(void)1005 static inline ktime_t tick_get_next_period(void)
1006 {
1007 	ktime_t next;
1008 
1009 	/*
1010 	 * Protect against concurrent updates (store /load tearing on
1011 	 * 32bit). It does not matter if the time is already in the
1012 	 * past. The broadcast device which is about to be programmed will
1013 	 * fire in any case.
1014 	 */
1015 	raw_spin_lock(&jiffies_lock);
1016 	next = tick_next_period;
1017 	raw_spin_unlock(&jiffies_lock);
1018 	return next;
1019 }
1020 
1021 /**
1022  * tick_broadcast_setup_oneshot - setup the broadcast device
1023  */
tick_broadcast_setup_oneshot(struct clock_event_device * bc,bool from_periodic)1024 static void tick_broadcast_setup_oneshot(struct clock_event_device *bc,
1025 					 bool from_periodic)
1026 {
1027 	int cpu = smp_processor_id();
1028 	ktime_t nexttick = 0;
1029 
1030 	if (!bc)
1031 		return;
1032 
1033 	/*
1034 	 * When the broadcast device was switched to oneshot by the first
1035 	 * CPU handling the NOHZ change, the other CPUs will reach this
1036 	 * code via hrtimer_run_queues() -> tick_check_oneshot_change()
1037 	 * too. Set up the broadcast device only once!
1038 	 */
1039 	if (bc->event_handler == tick_handle_oneshot_broadcast) {
1040 		/*
1041 		 * The CPU which switched from periodic to oneshot mode
1042 		 * set the broadcast oneshot bit for all other CPUs which
1043 		 * are in the general (periodic) broadcast mask to ensure
1044 		 * that CPUs which wait for the periodic broadcast are
1045 		 * woken up.
1046 		 *
1047 		 * Clear the bit for the local CPU as the set bit would
1048 		 * prevent the first tick_broadcast_enter() after this CPU
1049 		 * switched to oneshot state to program the broadcast
1050 		 * device.
1051 		 *
1052 		 * This code can also be reached via tick_broadcast_control(),
1053 		 * but this cannot avoid the tick_broadcast_clear_oneshot()
1054 		 * as that would break the periodic to oneshot transition of
1055 		 * secondary CPUs. But that's harmless as the below only
1056 		 * clears already cleared bits.
1057 		 */
1058 		tick_broadcast_clear_oneshot(cpu);
1059 		return;
1060 	}
1061 
1062 
1063 	bc->event_handler = tick_handle_oneshot_broadcast;
1064 	bc->next_event = KTIME_MAX;
1065 
1066 	/*
1067 	 * When the tick mode is switched from periodic to oneshot it must
1068 	 * be ensured that CPUs which are waiting for periodic broadcast
1069 	 * get their wake-up at the next tick.  This is achieved by ORing
1070 	 * tick_broadcast_mask into tick_broadcast_oneshot_mask.
1071 	 *
1072 	 * For other callers, e.g. broadcast device replacement,
1073 	 * tick_broadcast_oneshot_mask must not be touched as this would
1074 	 * set bits for CPUs which are already NOHZ, but not idle. Their
1075 	 * next tick_broadcast_enter() would observe the bit set and fail
1076 	 * to update the expiry time and the broadcast event device.
1077 	 */
1078 	if (from_periodic) {
1079 		cpumask_copy(tmpmask, tick_broadcast_mask);
1080 		/* Remove the local CPU as it is obviously not idle */
1081 		cpumask_clear_cpu(cpu, tmpmask);
1082 		cpumask_or(tick_broadcast_oneshot_mask, tick_broadcast_oneshot_mask, tmpmask);
1083 
1084 		/*
1085 		 * Ensure that the oneshot broadcast handler will wake the
1086 		 * CPUs which are still waiting for periodic broadcast.
1087 		 */
1088 		nexttick = tick_get_next_period();
1089 		tick_broadcast_init_next_event(tmpmask, nexttick);
1090 
1091 		/*
1092 		 * If the underlying broadcast clock event device is
1093 		 * already in oneshot state, then there is nothing to do.
1094 		 * The device was already armed for the next tick
1095 		 * in tick_handle_broadcast_periodic()
1096 		 */
1097 		if (clockevent_state_oneshot(bc))
1098 			return;
1099 	}
1100 
1101 	/*
1102 	 * When switching from periodic to oneshot mode arm the broadcast
1103 	 * device for the next tick.
1104 	 *
1105 	 * If the broadcast device has been replaced in oneshot mode and
1106 	 * the oneshot broadcast mask is not empty, then arm it to expire
1107 	 * immediately in order to reevaluate the next expiring timer.
1108 	 * @nexttick is 0 and therefore in the past which will cause the
1109 	 * clockevent code to force an event.
1110 	 *
1111 	 * For both cases the programming can be avoided when the oneshot
1112 	 * broadcast mask is empty.
1113 	 *
1114 	 * tick_broadcast_set_event() implicitly switches the broadcast
1115 	 * device to oneshot state.
1116 	 */
1117 	if (!cpumask_empty(tick_broadcast_oneshot_mask))
1118 		tick_broadcast_set_event(bc, cpu, nexttick);
1119 }
1120 
1121 /*
1122  * Select oneshot operating mode for the broadcast device
1123  */
tick_broadcast_switch_to_oneshot(void)1124 void tick_broadcast_switch_to_oneshot(void)
1125 {
1126 	struct clock_event_device *bc;
1127 	enum tick_device_mode oldmode;
1128 	unsigned long flags;
1129 
1130 	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
1131 
1132 	oldmode = tick_broadcast_device.mode;
1133 	tick_broadcast_device.mode = TICKDEV_MODE_ONESHOT;
1134 	bc = tick_broadcast_device.evtdev;
1135 	if (bc)
1136 		tick_broadcast_setup_oneshot(bc, oldmode == TICKDEV_MODE_PERIODIC);
1137 
1138 	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
1139 }
1140 
1141 #ifdef CONFIG_HOTPLUG_CPU
hotplug_cpu__broadcast_tick_pull(int deadcpu)1142 void hotplug_cpu__broadcast_tick_pull(int deadcpu)
1143 {
1144 	struct clock_event_device *bc;
1145 	unsigned long flags;
1146 
1147 	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
1148 	bc = tick_broadcast_device.evtdev;
1149 
1150 	if (bc && broadcast_needs_cpu(bc, deadcpu)) {
1151 		/*
1152 		 * If the broadcast force bit of the current CPU is set,
1153 		 * then the current CPU has not yet reprogrammed the local
1154 		 * timer device to avoid a ping-pong race. See
1155 		 * ___tick_broadcast_oneshot_control().
1156 		 *
1157 		 * If the broadcast device is hrtimer based then
1158 		 * programming the broadcast event below does not have any
1159 		 * effect because the local clockevent device is not
1160 		 * running and not programmed because the broadcast event
1161 		 * is not earlier than the pending event of the local clock
1162 		 * event device. As a consequence all CPUs waiting for a
1163 		 * broadcast event are stuck forever.
1164 		 *
1165 		 * Detect this condition and reprogram the cpu local timer
1166 		 * device to avoid the starvation.
1167 		 */
1168 		if (tick_check_broadcast_expired()) {
1169 			struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
1170 
1171 			cpumask_clear_cpu(smp_processor_id(), tick_broadcast_force_mask);
1172 			tick_program_event(td->evtdev->next_event, 1);
1173 		}
1174 
1175 		/* This moves the broadcast assignment to this CPU: */
1176 		clockevents_program_event(bc, bc->next_event, 1);
1177 	}
1178 	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
1179 }
1180 
1181 /*
1182  * Remove a dying CPU from broadcasting
1183  */
tick_broadcast_oneshot_offline(unsigned int cpu)1184 static void tick_broadcast_oneshot_offline(unsigned int cpu)
1185 {
1186 	if (tick_get_oneshot_wakeup_device(cpu))
1187 		tick_set_oneshot_wakeup_device(NULL, cpu);
1188 
1189 	/*
1190 	 * Clear the broadcast masks for the dead cpu, but do not stop
1191 	 * the broadcast device!
1192 	 */
1193 	cpumask_clear_cpu(cpu, tick_broadcast_oneshot_mask);
1194 	cpumask_clear_cpu(cpu, tick_broadcast_pending_mask);
1195 	cpumask_clear_cpu(cpu, tick_broadcast_force_mask);
1196 }
1197 #endif
1198 
1199 /*
1200  * Check, whether the broadcast device is in one shot mode
1201  */
tick_broadcast_oneshot_active(void)1202 int tick_broadcast_oneshot_active(void)
1203 {
1204 	return tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT;
1205 }
1206 
1207 /*
1208  * Check whether the broadcast device supports oneshot.
1209  */
tick_broadcast_oneshot_available(void)1210 bool tick_broadcast_oneshot_available(void)
1211 {
1212 	struct clock_event_device *bc = tick_broadcast_device.evtdev;
1213 
1214 	return bc ? bc->features & CLOCK_EVT_FEAT_ONESHOT : false;
1215 }
1216 
1217 #else
__tick_broadcast_oneshot_control(enum tick_broadcast_state state)1218 int __tick_broadcast_oneshot_control(enum tick_broadcast_state state)
1219 {
1220 	struct clock_event_device *bc = tick_broadcast_device.evtdev;
1221 
1222 	if (!bc || (bc->features & CLOCK_EVT_FEAT_HRTIMER))
1223 		return -EBUSY;
1224 
1225 	return 0;
1226 }
1227 #endif
1228 
tick_broadcast_init(void)1229 void __init tick_broadcast_init(void)
1230 {
1231 	zalloc_cpumask_var(&tick_broadcast_mask, GFP_NOWAIT);
1232 	zalloc_cpumask_var(&tick_broadcast_on, GFP_NOWAIT);
1233 	zalloc_cpumask_var(&tmpmask, GFP_NOWAIT);
1234 #ifdef CONFIG_TICK_ONESHOT
1235 	zalloc_cpumask_var(&tick_broadcast_oneshot_mask, GFP_NOWAIT);
1236 	zalloc_cpumask_var(&tick_broadcast_pending_mask, GFP_NOWAIT);
1237 	zalloc_cpumask_var(&tick_broadcast_force_mask, GFP_NOWAIT);
1238 #endif
1239 }
1240