Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0
2 : /*
3 : * Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
4 : * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
5 : * Copyright(C) 2006-2007 Timesys Corp., Thomas Gleixner
6 : *
7 : * High-resolution kernel timers
8 : *
9 : * In contrast to the low-resolution timeout API, aka timer wheel,
10 : * hrtimers provide finer resolution and accuracy depending on system
11 : * configuration and capabilities.
12 : *
13 : * Started by: Thomas Gleixner and Ingo Molnar
14 : *
15 : * Credits:
16 : * Based on the original timer wheel code
17 : *
18 : * Help, testing, suggestions, bugfixes, improvements were
19 : * provided by:
20 : *
21 : * George Anzinger, Andrew Morton, Steven Rostedt, Roman Zippel
22 : * et. al.
23 : */
24 :
25 : #include <linux/cpu.h>
26 : #include <linux/export.h>
27 : #include <linux/percpu.h>
28 : #include <linux/hrtimer.h>
29 : #include <linux/notifier.h>
30 : #include <linux/syscalls.h>
31 : #include <linux/interrupt.h>
32 : #include <linux/tick.h>
33 : #include <linux/err.h>
34 : #include <linux/debugobjects.h>
35 : #include <linux/sched/signal.h>
36 : #include <linux/sched/sysctl.h>
37 : #include <linux/sched/rt.h>
38 : #include <linux/sched/deadline.h>
39 : #include <linux/sched/nohz.h>
40 : #include <linux/sched/debug.h>
41 : #include <linux/timer.h>
42 : #include <linux/freezer.h>
43 : #include <linux/compat.h>
44 :
45 : #include <linux/uaccess.h>
46 :
47 : #include <trace/events/timer.h>
48 :
49 : #include "tick-internal.h"
50 :
51 : /*
52 : * Masks for selecting the soft and hard context timers from
53 : * cpu_base->active
54 : */
55 : #define MASK_SHIFT (HRTIMER_BASE_MONOTONIC_SOFT)
56 : #define HRTIMER_ACTIVE_HARD ((1U << MASK_SHIFT) - 1)
57 : #define HRTIMER_ACTIVE_SOFT (HRTIMER_ACTIVE_HARD << MASK_SHIFT)
58 : #define HRTIMER_ACTIVE_ALL (HRTIMER_ACTIVE_SOFT | HRTIMER_ACTIVE_HARD)
59 :
60 : /*
61 : * The timer bases:
62 : *
63 : * There are more clockids than hrtimer bases. Thus, we index
64 : * into the timer bases by the hrtimer_base_type enum. When trying
65 : * to reach a base using a clockid, hrtimer_clockid_to_base()
66 : * is used to convert from clockid to the proper hrtimer_base_type.
67 : */
68 : DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) =
69 : {
70 : .lock = __RAW_SPIN_LOCK_UNLOCKED(hrtimer_bases.lock),
71 : .clock_base =
72 : {
73 : {
74 : .index = HRTIMER_BASE_MONOTONIC,
75 : .clockid = CLOCK_MONOTONIC,
76 : .get_time = &ktime_get,
77 : },
78 : {
79 : .index = HRTIMER_BASE_REALTIME,
80 : .clockid = CLOCK_REALTIME,
81 : .get_time = &ktime_get_real,
82 : },
83 : {
84 : .index = HRTIMER_BASE_BOOTTIME,
85 : .clockid = CLOCK_BOOTTIME,
86 : .get_time = &ktime_get_boottime,
87 : },
88 : {
89 : .index = HRTIMER_BASE_TAI,
90 : .clockid = CLOCK_TAI,
91 : .get_time = &ktime_get_clocktai,
92 : },
93 : {
94 : .index = HRTIMER_BASE_MONOTONIC_SOFT,
95 : .clockid = CLOCK_MONOTONIC,
96 : .get_time = &ktime_get,
97 : },
98 : {
99 : .index = HRTIMER_BASE_REALTIME_SOFT,
100 : .clockid = CLOCK_REALTIME,
101 : .get_time = &ktime_get_real,
102 : },
103 : {
104 : .index = HRTIMER_BASE_BOOTTIME_SOFT,
105 : .clockid = CLOCK_BOOTTIME,
106 : .get_time = &ktime_get_boottime,
107 : },
108 : {
109 : .index = HRTIMER_BASE_TAI_SOFT,
110 : .clockid = CLOCK_TAI,
111 : .get_time = &ktime_get_clocktai,
112 : },
113 : }
114 : };
115 :
116 : static const int hrtimer_clock_to_base_table[MAX_CLOCKS] = {
117 : /* Make sure we catch unsupported clockids */
118 : [0 ... MAX_CLOCKS - 1] = HRTIMER_MAX_CLOCK_BASES,
119 :
120 : [CLOCK_REALTIME] = HRTIMER_BASE_REALTIME,
121 : [CLOCK_MONOTONIC] = HRTIMER_BASE_MONOTONIC,
122 : [CLOCK_BOOTTIME] = HRTIMER_BASE_BOOTTIME,
123 : [CLOCK_TAI] = HRTIMER_BASE_TAI,
124 : };
125 :
126 : /*
127 : * Functions and macros which are different for UP/SMP systems are kept in a
128 : * single place
129 : */
130 : #ifdef CONFIG_SMP
131 :
132 : /*
133 : * We require the migration_base for lock_hrtimer_base()/switch_hrtimer_base()
134 : * such that hrtimer_callback_running() can unconditionally dereference
135 : * timer->base->cpu_base
136 : */
137 : static struct hrtimer_cpu_base migration_cpu_base = {
138 : .clock_base = { {
139 : .cpu_base = &migration_cpu_base,
140 : .seq = SEQCNT_RAW_SPINLOCK_ZERO(migration_cpu_base.seq,
141 : &migration_cpu_base.lock),
142 : }, },
143 : };
144 :
145 : #define migration_base migration_cpu_base.clock_base[0]
146 :
147 : static inline bool is_migration_base(struct hrtimer_clock_base *base)
148 : {
149 : return base == &migration_base;
150 : }
151 :
152 : /*
153 : * We are using hashed locking: holding per_cpu(hrtimer_bases)[n].lock
154 : * means that all timers which are tied to this base via timer->base are
155 : * locked, and the base itself is locked too.
156 : *
157 : * So __run_timers/migrate_timers can safely modify all timers which could
158 : * be found on the lists/queues.
159 : *
160 : * When the timer's base is locked, and the timer removed from list, it is
161 : * possible to set timer->base = &migration_base and drop the lock: the timer
162 : * remains locked.
163 : */
164 : static
165 : struct hrtimer_clock_base *lock_hrtimer_base(const struct hrtimer *timer,
166 : unsigned long *flags)
167 : __acquires(&timer->base->lock)
168 : {
169 : struct hrtimer_clock_base *base;
170 :
171 : for (;;) {
172 : base = READ_ONCE(timer->base);
173 : if (likely(base != &migration_base)) {
174 : raw_spin_lock_irqsave(&base->cpu_base->lock, *flags);
175 : if (likely(base == timer->base))
176 : return base;
177 : /* The timer has migrated to another CPU: */
178 : raw_spin_unlock_irqrestore(&base->cpu_base->lock, *flags);
179 : }
180 : cpu_relax();
181 : }
182 : }
183 :
184 : /*
185 : * We do not migrate the timer when it is expiring before the next
186 : * event on the target cpu. When high resolution is enabled, we cannot
187 : * reprogram the target cpu hardware and we would cause it to fire
188 : * late. To keep it simple, we handle the high resolution enabled and
189 : * disabled case similar.
190 : *
191 : * Called with cpu_base->lock of target cpu held.
192 : */
193 : static int
194 : hrtimer_check_target(struct hrtimer *timer, struct hrtimer_clock_base *new_base)
195 : {
196 : ktime_t expires;
197 :
198 : expires = ktime_sub(hrtimer_get_expires(timer), new_base->offset);
199 : return expires < new_base->cpu_base->expires_next;
200 : }
201 :
202 : static inline
203 : struct hrtimer_cpu_base *get_target_base(struct hrtimer_cpu_base *base,
204 : int pinned)
205 : {
206 : #if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ_COMMON)
207 : if (static_branch_likely(&timers_migration_enabled) && !pinned)
208 : return &per_cpu(hrtimer_bases, get_nohz_timer_target());
209 : #endif
210 : return base;
211 : }
212 :
213 : /*
214 : * We switch the timer base to a power-optimized selected CPU target,
215 : * if:
216 : * - NO_HZ_COMMON is enabled
217 : * - timer migration is enabled
218 : * - the timer callback is not running
219 : * - the timer is not the first expiring timer on the new target
220 : *
221 : * If one of the above requirements is not fulfilled we move the timer
222 : * to the current CPU or leave it on the previously assigned CPU if
223 : * the timer callback is currently running.
224 : */
225 : static inline struct hrtimer_clock_base *
226 : switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base,
227 : int pinned)
228 : {
229 : struct hrtimer_cpu_base *new_cpu_base, *this_cpu_base;
230 : struct hrtimer_clock_base *new_base;
231 : int basenum = base->index;
232 :
233 : this_cpu_base = this_cpu_ptr(&hrtimer_bases);
234 : new_cpu_base = get_target_base(this_cpu_base, pinned);
235 : again:
236 : new_base = &new_cpu_base->clock_base[basenum];
237 :
238 : if (base != new_base) {
239 : /*
240 : * We are trying to move timer to new_base.
241 : * However we can't change timer's base while it is running,
242 : * so we keep it on the same CPU. No hassle vs. reprogramming
243 : * the event source in the high resolution case. The softirq
244 : * code will take care of this when the timer function has
245 : * completed. There is no conflict as we hold the lock until
246 : * the timer is enqueued.
247 : */
248 : if (unlikely(hrtimer_callback_running(timer)))
249 : return base;
250 :
251 : /* See the comment in lock_hrtimer_base() */
252 : WRITE_ONCE(timer->base, &migration_base);
253 : raw_spin_unlock(&base->cpu_base->lock);
254 : raw_spin_lock(&new_base->cpu_base->lock);
255 :
256 : if (new_cpu_base != this_cpu_base &&
257 : hrtimer_check_target(timer, new_base)) {
258 : raw_spin_unlock(&new_base->cpu_base->lock);
259 : raw_spin_lock(&base->cpu_base->lock);
260 : new_cpu_base = this_cpu_base;
261 : WRITE_ONCE(timer->base, base);
262 : goto again;
263 : }
264 : WRITE_ONCE(timer->base, new_base);
265 : } else {
266 : if (new_cpu_base != this_cpu_base &&
267 : hrtimer_check_target(timer, new_base)) {
268 : new_cpu_base = this_cpu_base;
269 : goto again;
270 : }
271 : }
272 : return new_base;
273 : }
274 :
275 : #else /* CONFIG_SMP */
276 :
277 : static inline bool is_migration_base(struct hrtimer_clock_base *base)
278 : {
279 : return false;
280 : }
281 :
282 : static inline struct hrtimer_clock_base *
283 : lock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
284 : __acquires(&timer->base->cpu_base->lock)
285 : {
286 0 : struct hrtimer_clock_base *base = timer->base;
287 :
288 0 : raw_spin_lock_irqsave(&base->cpu_base->lock, *flags);
289 :
290 : return base;
291 : }
292 :
293 : # define switch_hrtimer_base(t, b, p) (b)
294 :
295 : #endif /* !CONFIG_SMP */
296 :
297 : /*
298 : * Functions for the union type storage format of ktime_t which are
299 : * too large for inlining:
300 : */
301 : #if BITS_PER_LONG < 64
302 : /*
303 : * Divide a ktime value by a nanosecond value
304 : */
305 : s64 __ktime_divns(const ktime_t kt, s64 div)
306 : {
307 : int sft = 0;
308 : s64 dclc;
309 : u64 tmp;
310 :
311 : dclc = ktime_to_ns(kt);
312 : tmp = dclc < 0 ? -dclc : dclc;
313 :
314 : /* Make sure the divisor is less than 2^32: */
315 : while (div >> 32) {
316 : sft++;
317 : div >>= 1;
318 : }
319 : tmp >>= sft;
320 : do_div(tmp, (u32) div);
321 : return dclc < 0 ? -tmp : tmp;
322 : }
323 : EXPORT_SYMBOL_GPL(__ktime_divns);
324 : #endif /* BITS_PER_LONG >= 64 */
325 :
326 : /*
327 : * Add two ktime values and do a safety check for overflow:
328 : */
329 0 : ktime_t ktime_add_safe(const ktime_t lhs, const ktime_t rhs)
330 : {
331 0 : ktime_t res = ktime_add_unsafe(lhs, rhs);
332 :
333 : /*
334 : * We use KTIME_SEC_MAX here, the maximum timeout which we can
335 : * return to user space in a timespec:
336 : */
337 0 : if (res < 0 || res < lhs || res < rhs)
338 0 : res = ktime_set(KTIME_SEC_MAX, 0);
339 :
340 0 : return res;
341 : }
342 :
343 : EXPORT_SYMBOL_GPL(ktime_add_safe);
344 :
345 : #ifdef CONFIG_DEBUG_OBJECTS_TIMERS
346 :
347 : static const struct debug_obj_descr hrtimer_debug_descr;
348 :
349 : static void *hrtimer_debug_hint(void *addr)
350 : {
351 : return ((struct hrtimer *) addr)->function;
352 : }
353 :
354 : /*
355 : * fixup_init is called when:
356 : * - an active object is initialized
357 : */
358 : static bool hrtimer_fixup_init(void *addr, enum debug_obj_state state)
359 : {
360 : struct hrtimer *timer = addr;
361 :
362 : switch (state) {
363 : case ODEBUG_STATE_ACTIVE:
364 : hrtimer_cancel(timer);
365 : debug_object_init(timer, &hrtimer_debug_descr);
366 : return true;
367 : default:
368 : return false;
369 : }
370 : }
371 :
372 : /*
373 : * fixup_activate is called when:
374 : * - an active object is activated
375 : * - an unknown non-static object is activated
376 : */
377 : static bool hrtimer_fixup_activate(void *addr, enum debug_obj_state state)
378 : {
379 : switch (state) {
380 : case ODEBUG_STATE_ACTIVE:
381 : WARN_ON(1);
382 : fallthrough;
383 : default:
384 : return false;
385 : }
386 : }
387 :
388 : /*
389 : * fixup_free is called when:
390 : * - an active object is freed
391 : */
392 : static bool hrtimer_fixup_free(void *addr, enum debug_obj_state state)
393 : {
394 : struct hrtimer *timer = addr;
395 :
396 : switch (state) {
397 : case ODEBUG_STATE_ACTIVE:
398 : hrtimer_cancel(timer);
399 : debug_object_free(timer, &hrtimer_debug_descr);
400 : return true;
401 : default:
402 : return false;
403 : }
404 : }
405 :
406 : static const struct debug_obj_descr hrtimer_debug_descr = {
407 : .name = "hrtimer",
408 : .debug_hint = hrtimer_debug_hint,
409 : .fixup_init = hrtimer_fixup_init,
410 : .fixup_activate = hrtimer_fixup_activate,
411 : .fixup_free = hrtimer_fixup_free,
412 : };
413 :
414 : static inline void debug_hrtimer_init(struct hrtimer *timer)
415 : {
416 : debug_object_init(timer, &hrtimer_debug_descr);
417 : }
418 :
419 : static inline void debug_hrtimer_activate(struct hrtimer *timer,
420 : enum hrtimer_mode mode)
421 : {
422 : debug_object_activate(timer, &hrtimer_debug_descr);
423 : }
424 :
425 : static inline void debug_hrtimer_deactivate(struct hrtimer *timer)
426 : {
427 : debug_object_deactivate(timer, &hrtimer_debug_descr);
428 : }
429 :
430 : static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
431 : enum hrtimer_mode mode);
432 :
433 : void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t clock_id,
434 : enum hrtimer_mode mode)
435 : {
436 : debug_object_init_on_stack(timer, &hrtimer_debug_descr);
437 : __hrtimer_init(timer, clock_id, mode);
438 : }
439 : EXPORT_SYMBOL_GPL(hrtimer_init_on_stack);
440 :
441 : static void __hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
442 : clockid_t clock_id, enum hrtimer_mode mode);
443 :
444 : void hrtimer_init_sleeper_on_stack(struct hrtimer_sleeper *sl,
445 : clockid_t clock_id, enum hrtimer_mode mode)
446 : {
447 : debug_object_init_on_stack(&sl->timer, &hrtimer_debug_descr);
448 : __hrtimer_init_sleeper(sl, clock_id, mode);
449 : }
450 : EXPORT_SYMBOL_GPL(hrtimer_init_sleeper_on_stack);
451 :
452 : void destroy_hrtimer_on_stack(struct hrtimer *timer)
453 : {
454 : debug_object_free(timer, &hrtimer_debug_descr);
455 : }
456 : EXPORT_SYMBOL_GPL(destroy_hrtimer_on_stack);
457 :
458 : #else
459 :
460 : static inline void debug_hrtimer_init(struct hrtimer *timer) { }
461 : static inline void debug_hrtimer_activate(struct hrtimer *timer,
462 : enum hrtimer_mode mode) { }
463 : static inline void debug_hrtimer_deactivate(struct hrtimer *timer) { }
464 : #endif
465 :
466 : static inline void
467 : debug_init(struct hrtimer *timer, clockid_t clockid,
468 : enum hrtimer_mode mode)
469 : {
470 1073 : debug_hrtimer_init(timer);
471 1073 : trace_hrtimer_init(timer, clockid, mode);
472 : }
473 :
474 : static inline void debug_activate(struct hrtimer *timer,
475 : enum hrtimer_mode mode)
476 : {
477 0 : debug_hrtimer_activate(timer, mode);
478 0 : trace_hrtimer_start(timer, mode);
479 : }
480 :
481 : static inline void debug_deactivate(struct hrtimer *timer)
482 : {
483 0 : debug_hrtimer_deactivate(timer);
484 0 : trace_hrtimer_cancel(timer);
485 : }
486 :
487 : static struct hrtimer_clock_base *
488 : __next_base(struct hrtimer_cpu_base *cpu_base, unsigned int *active)
489 : {
490 : unsigned int idx;
491 :
492 5 : if (!*active)
493 : return NULL;
494 :
495 0 : idx = __ffs(*active);
496 0 : *active &= ~(1U << idx);
497 :
498 0 : return &cpu_base->clock_base[idx];
499 : }
500 :
501 : #define for_each_active_base(base, cpu_base, active) \
502 : while ((base = __next_base((cpu_base), &(active))))
503 :
504 0 : static ktime_t __hrtimer_next_event_base(struct hrtimer_cpu_base *cpu_base,
505 : const struct hrtimer *exclude,
506 : unsigned int active,
507 : ktime_t expires_next)
508 : {
509 : struct hrtimer_clock_base *base;
510 : ktime_t expires;
511 :
512 0 : for_each_active_base(base, cpu_base, active) {
513 : struct timerqueue_node *next;
514 : struct hrtimer *timer;
515 :
516 0 : next = timerqueue_getnext(&base->active);
517 0 : timer = container_of(next, struct hrtimer, node);
518 0 : if (timer == exclude) {
519 : /* Get to the next timer in the queue. */
520 0 : next = timerqueue_iterate_next(next);
521 0 : if (!next)
522 0 : continue;
523 :
524 : timer = container_of(next, struct hrtimer, node);
525 : }
526 0 : expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
527 0 : if (expires < expires_next) {
528 0 : expires_next = expires;
529 :
530 : /* Skip cpu_base update if a timer is being excluded. */
531 0 : if (exclude)
532 0 : continue;
533 :
534 0 : if (timer->is_soft)
535 0 : cpu_base->softirq_next_timer = timer;
536 : else
537 0 : cpu_base->next_timer = timer;
538 : }
539 : }
540 : /*
541 : * clock_was_set() might have changed base->offset of any of
542 : * the clock bases so the result might be negative. Fix it up
543 : * to prevent a false positive in clockevents_program_event().
544 : */
545 0 : if (expires_next < 0)
546 0 : expires_next = 0;
547 0 : return expires_next;
548 : }
549 :
550 : /*
551 : * Recomputes cpu_base::*next_timer and returns the earliest expires_next
552 : * but does not set cpu_base::*expires_next, that is done by
553 : * hrtimer[_force]_reprogram and hrtimer_interrupt only. When updating
554 : * cpu_base::*expires_next right away, reprogramming logic would no longer
555 : * work.
556 : *
557 : * When a softirq is pending, we can ignore the HRTIMER_ACTIVE_SOFT bases,
558 : * those timers will get run whenever the softirq gets handled, at the end of
559 : * hrtimer_run_softirq(), hrtimer_update_softirq_timer() will re-add these bases.
560 : *
561 : * Therefore softirq values are those from the HRTIMER_ACTIVE_SOFT clock bases.
562 : * The !softirq values are the minima across HRTIMER_ACTIVE_ALL, unless an actual
563 : * softirq is pending, in which case they're the minima of HRTIMER_ACTIVE_HARD.
564 : *
565 : * @active_mask must be one of:
566 : * - HRTIMER_ACTIVE_ALL,
567 : * - HRTIMER_ACTIVE_SOFT, or
568 : * - HRTIMER_ACTIVE_HARD.
569 : */
570 : static ktime_t
571 0 : __hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base, unsigned int active_mask)
572 : {
573 : unsigned int active;
574 0 : struct hrtimer *next_timer = NULL;
575 0 : ktime_t expires_next = KTIME_MAX;
576 :
577 0 : if (!cpu_base->softirq_activated && (active_mask & HRTIMER_ACTIVE_SOFT)) {
578 0 : active = cpu_base->active_bases & HRTIMER_ACTIVE_SOFT;
579 0 : cpu_base->softirq_next_timer = NULL;
580 0 : expires_next = __hrtimer_next_event_base(cpu_base, NULL,
581 : active, KTIME_MAX);
582 :
583 0 : next_timer = cpu_base->softirq_next_timer;
584 : }
585 :
586 0 : if (active_mask & HRTIMER_ACTIVE_HARD) {
587 0 : active = cpu_base->active_bases & HRTIMER_ACTIVE_HARD;
588 0 : cpu_base->next_timer = next_timer;
589 0 : expires_next = __hrtimer_next_event_base(cpu_base, NULL, active,
590 : expires_next);
591 : }
592 :
593 0 : return expires_next;
594 : }
595 :
596 0 : static ktime_t hrtimer_update_next_event(struct hrtimer_cpu_base *cpu_base)
597 : {
598 0 : ktime_t expires_next, soft = KTIME_MAX;
599 :
600 : /*
601 : * If the soft interrupt has already been activated, ignore the
602 : * soft bases. They will be handled in the already raised soft
603 : * interrupt.
604 : */
605 0 : if (!cpu_base->softirq_activated) {
606 0 : soft = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_SOFT);
607 : /*
608 : * Update the soft expiry time. clock_settime() might have
609 : * affected it.
610 : */
611 0 : cpu_base->softirq_expires_next = soft;
612 : }
613 :
614 0 : expires_next = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_HARD);
615 : /*
616 : * If a softirq timer is expiring first, update cpu_base->next_timer
617 : * and program the hardware with the soft expiry time.
618 : */
619 0 : if (expires_next > soft) {
620 0 : cpu_base->next_timer = cpu_base->softirq_next_timer;
621 0 : expires_next = soft;
622 : }
623 :
624 0 : return expires_next;
625 : }
626 :
627 : static inline ktime_t hrtimer_update_base(struct hrtimer_cpu_base *base)
628 : {
629 5 : ktime_t *offs_real = &base->clock_base[HRTIMER_BASE_REALTIME].offset;
630 5 : ktime_t *offs_boot = &base->clock_base[HRTIMER_BASE_BOOTTIME].offset;
631 5 : ktime_t *offs_tai = &base->clock_base[HRTIMER_BASE_TAI].offset;
632 :
633 5 : ktime_t now = ktime_get_update_offsets_now(&base->clock_was_set_seq,
634 : offs_real, offs_boot, offs_tai);
635 :
636 5 : base->clock_base[HRTIMER_BASE_REALTIME_SOFT].offset = *offs_real;
637 5 : base->clock_base[HRTIMER_BASE_BOOTTIME_SOFT].offset = *offs_boot;
638 5 : base->clock_base[HRTIMER_BASE_TAI_SOFT].offset = *offs_tai;
639 :
640 : return now;
641 : }
642 :
643 : /*
644 : * Is the high resolution mode active ?
645 : */
646 : static inline int __hrtimer_hres_active(struct hrtimer_cpu_base *cpu_base)
647 : {
648 : return IS_ENABLED(CONFIG_HIGH_RES_TIMERS) ?
649 : cpu_base->hres_active : 0;
650 : }
651 :
652 : static inline int hrtimer_hres_active(void)
653 : {
654 : return __hrtimer_hres_active(this_cpu_ptr(&hrtimer_bases));
655 : }
656 :
657 : static void __hrtimer_reprogram(struct hrtimer_cpu_base *cpu_base,
658 : struct hrtimer *next_timer,
659 : ktime_t expires_next)
660 : {
661 0 : cpu_base->expires_next = expires_next;
662 :
663 : /*
664 : * If hres is not active, hardware does not have to be
665 : * reprogrammed yet.
666 : *
667 : * If a hang was detected in the last timer interrupt then we
668 : * leave the hang delay active in the hardware. We want the
669 : * system to make progress. That also prevents the following
670 : * scenario:
671 : * T1 expires 50ms from now
672 : * T2 expires 5s from now
673 : *
674 : * T1 is removed, so this code is called and would reprogram
675 : * the hardware to 5s from now. Any hrtimer_start after that
676 : * will not reprogram the hardware due to hang_detected being
677 : * set. So we'd effectively block all timers until the T2 event
678 : * fires.
679 : */
680 0 : if (!__hrtimer_hres_active(cpu_base) || cpu_base->hang_detected)
681 : return;
682 :
683 : tick_program_event(expires_next, 1);
684 : }
685 :
686 : /*
687 : * Reprogram the event source with checking both queues for the
688 : * next event
689 : * Called with interrupts disabled and base->lock held
690 : */
691 : static void
692 : hrtimer_force_reprogram(struct hrtimer_cpu_base *cpu_base, int skip_equal)
693 : {
694 : ktime_t expires_next;
695 :
696 0 : expires_next = hrtimer_update_next_event(cpu_base);
697 :
698 0 : if (skip_equal && expires_next == cpu_base->expires_next)
699 : return;
700 :
701 0 : __hrtimer_reprogram(cpu_base, cpu_base->next_timer, expires_next);
702 : }
703 :
704 : /* High resolution timer related functions */
705 : #ifdef CONFIG_HIGH_RES_TIMERS
706 :
707 : /*
708 : * High resolution timer enabled ?
709 : */
710 : static bool hrtimer_hres_enabled __read_mostly = true;
711 : unsigned int hrtimer_resolution __read_mostly = LOW_RES_NSEC;
712 : EXPORT_SYMBOL_GPL(hrtimer_resolution);
713 :
714 : /*
715 : * Enable / Disable high resolution mode
716 : */
717 : static int __init setup_hrtimer_hres(char *str)
718 : {
719 : return (kstrtobool(str, &hrtimer_hres_enabled) == 0);
720 : }
721 :
722 : __setup("highres=", setup_hrtimer_hres);
723 :
724 : /*
725 : * hrtimer_high_res_enabled - query, if the highres mode is enabled
726 : */
727 : static inline int hrtimer_is_hres_enabled(void)
728 : {
729 : return hrtimer_hres_enabled;
730 : }
731 :
732 : static void retrigger_next_event(void *arg);
733 :
734 : /*
735 : * Switch to high resolution mode
736 : */
737 : static void hrtimer_switch_to_hres(void)
738 : {
739 : struct hrtimer_cpu_base *base = this_cpu_ptr(&hrtimer_bases);
740 :
741 : if (tick_init_highres()) {
742 : pr_warn("Could not switch to high resolution mode on CPU %u\n",
743 : base->cpu);
744 : return;
745 : }
746 : base->hres_active = 1;
747 : hrtimer_resolution = HIGH_RES_NSEC;
748 :
749 : tick_setup_sched_timer();
750 : /* "Retrigger" the interrupt to get things going */
751 : retrigger_next_event(NULL);
752 : }
753 :
754 : #else
755 :
756 : static inline int hrtimer_is_hres_enabled(void) { return 0; }
757 : static inline void hrtimer_switch_to_hres(void) { }
758 :
759 : #endif /* CONFIG_HIGH_RES_TIMERS */
760 : /*
761 : * Retrigger next event is called after clock was set with interrupts
762 : * disabled through an SMP function call or directly from low level
763 : * resume code.
764 : *
765 : * This is only invoked when:
766 : * - CONFIG_HIGH_RES_TIMERS is enabled.
767 : * - CONFIG_NOHZ_COMMON is enabled
768 : *
769 : * For the other cases this function is empty and because the call sites
770 : * are optimized out it vanishes as well, i.e. no need for lots of
771 : * #ifdeffery.
772 : */
773 : static void retrigger_next_event(void *arg)
774 : {
775 0 : struct hrtimer_cpu_base *base = this_cpu_ptr(&hrtimer_bases);
776 :
777 : /*
778 : * When high resolution mode or nohz is active, then the offsets of
779 : * CLOCK_REALTIME/TAI/BOOTTIME have to be updated. Otherwise the
780 : * next tick will take care of that.
781 : *
782 : * If high resolution mode is active then the next expiring timer
783 : * must be reevaluated and the clock event device reprogrammed if
784 : * necessary.
785 : *
786 : * In the NOHZ case the update of the offset and the reevaluation
787 : * of the next expiring timer is enough. The return from the SMP
788 : * function call will take care of the reprogramming in case the
789 : * CPU was in a NOHZ idle sleep.
790 : */
791 0 : if (!__hrtimer_hres_active(base) && !tick_nohz_active)
792 : return;
793 :
794 : raw_spin_lock(&base->lock);
795 : hrtimer_update_base(base);
796 : if (__hrtimer_hres_active(base))
797 : hrtimer_force_reprogram(base, 0);
798 : else
799 : hrtimer_update_next_event(base);
800 : raw_spin_unlock(&base->lock);
801 : }
802 :
803 : /*
804 : * When a timer is enqueued and expires earlier than the already enqueued
805 : * timers, we have to check, whether it expires earlier than the timer for
806 : * which the clock event device was armed.
807 : *
808 : * Called with interrupts disabled and base->cpu_base.lock held
809 : */
810 0 : static void hrtimer_reprogram(struct hrtimer *timer, bool reprogram)
811 : {
812 0 : struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
813 0 : struct hrtimer_clock_base *base = timer->base;
814 0 : ktime_t expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
815 :
816 0 : WARN_ON_ONCE(hrtimer_get_expires_tv64(timer) < 0);
817 :
818 : /*
819 : * CLOCK_REALTIME timer might be requested with an absolute
820 : * expiry time which is less than base->offset. Set it to 0.
821 : */
822 0 : if (expires < 0)
823 0 : expires = 0;
824 :
825 0 : if (timer->is_soft) {
826 : /*
827 : * soft hrtimer could be started on a remote CPU. In this
828 : * case softirq_expires_next needs to be updated on the
829 : * remote CPU. The soft hrtimer will not expire before the
830 : * first hard hrtimer on the remote CPU -
831 : * hrtimer_check_target() prevents this case.
832 : */
833 0 : struct hrtimer_cpu_base *timer_cpu_base = base->cpu_base;
834 :
835 0 : if (timer_cpu_base->softirq_activated)
836 : return;
837 :
838 0 : if (!ktime_before(expires, timer_cpu_base->softirq_expires_next))
839 : return;
840 :
841 0 : timer_cpu_base->softirq_next_timer = timer;
842 0 : timer_cpu_base->softirq_expires_next = expires;
843 :
844 0 : if (!ktime_before(expires, timer_cpu_base->expires_next) ||
845 : !reprogram)
846 : return;
847 : }
848 :
849 : /*
850 : * If the timer is not on the current cpu, we cannot reprogram
851 : * the other cpus clock event device.
852 : */
853 0 : if (base->cpu_base != cpu_base)
854 : return;
855 :
856 0 : if (expires >= cpu_base->expires_next)
857 : return;
858 :
859 : /*
860 : * If the hrtimer interrupt is running, then it will reevaluate the
861 : * clock bases and reprogram the clock event device.
862 : */
863 0 : if (cpu_base->in_hrtirq)
864 : return;
865 :
866 0 : cpu_base->next_timer = timer;
867 :
868 0 : __hrtimer_reprogram(cpu_base, timer, expires);
869 : }
870 :
871 : static bool update_needs_ipi(struct hrtimer_cpu_base *cpu_base,
872 : unsigned int active)
873 : {
874 : struct hrtimer_clock_base *base;
875 : unsigned int seq;
876 : ktime_t expires;
877 :
878 : /*
879 : * Update the base offsets unconditionally so the following
880 : * checks whether the SMP function call is required works.
881 : *
882 : * The update is safe even when the remote CPU is in the hrtimer
883 : * interrupt or the hrtimer soft interrupt and expiring affected
884 : * bases. Either it will see the update before handling a base or
885 : * it will see it when it finishes the processing and reevaluates
886 : * the next expiring timer.
887 : */
888 : seq = cpu_base->clock_was_set_seq;
889 : hrtimer_update_base(cpu_base);
890 :
891 : /*
892 : * If the sequence did not change over the update then the
893 : * remote CPU already handled it.
894 : */
895 : if (seq == cpu_base->clock_was_set_seq)
896 : return false;
897 :
898 : /*
899 : * If the remote CPU is currently handling an hrtimer interrupt, it
900 : * will reevaluate the first expiring timer of all clock bases
901 : * before reprogramming. Nothing to do here.
902 : */
903 : if (cpu_base->in_hrtirq)
904 : return false;
905 :
906 : /*
907 : * Walk the affected clock bases and check whether the first expiring
908 : * timer in a clock base is moving ahead of the first expiring timer of
909 : * @cpu_base. If so, the IPI must be invoked because per CPU clock
910 : * event devices cannot be remotely reprogrammed.
911 : */
912 : active &= cpu_base->active_bases;
913 :
914 : for_each_active_base(base, cpu_base, active) {
915 : struct timerqueue_node *next;
916 :
917 : next = timerqueue_getnext(&base->active);
918 : expires = ktime_sub(next->expires, base->offset);
919 : if (expires < cpu_base->expires_next)
920 : return true;
921 :
922 : /* Extra check for softirq clock bases */
923 : if (base->clockid < HRTIMER_BASE_MONOTONIC_SOFT)
924 : continue;
925 : if (cpu_base->softirq_activated)
926 : continue;
927 : if (expires < cpu_base->softirq_expires_next)
928 : return true;
929 : }
930 : return false;
931 : }
932 :
933 : /*
934 : * Clock was set. This might affect CLOCK_REALTIME, CLOCK_TAI and
935 : * CLOCK_BOOTTIME (for late sleep time injection).
936 : *
937 : * This requires to update the offsets for these clocks
938 : * vs. CLOCK_MONOTONIC. When high resolution timers are enabled, then this
939 : * also requires to eventually reprogram the per CPU clock event devices
940 : * when the change moves an affected timer ahead of the first expiring
941 : * timer on that CPU. Obviously remote per CPU clock event devices cannot
942 : * be reprogrammed. The other reason why an IPI has to be sent is when the
943 : * system is in !HIGH_RES and NOHZ mode. The NOHZ mode updates the offsets
944 : * in the tick, which obviously might be stopped, so this has to bring out
945 : * the remote CPU which might sleep in idle to get this sorted.
946 : */
947 0 : void clock_was_set(unsigned int bases)
948 : {
949 0 : struct hrtimer_cpu_base *cpu_base = raw_cpu_ptr(&hrtimer_bases);
950 : cpumask_var_t mask;
951 : int cpu;
952 :
953 0 : if (!__hrtimer_hres_active(cpu_base) && !tick_nohz_active)
954 : goto out_timerfd;
955 :
956 : if (!zalloc_cpumask_var(&mask, GFP_KERNEL)) {
957 : on_each_cpu(retrigger_next_event, NULL, 1);
958 : goto out_timerfd;
959 : }
960 :
961 : /* Avoid interrupting CPUs if possible */
962 : cpus_read_lock();
963 : for_each_online_cpu(cpu) {
964 : unsigned long flags;
965 :
966 : cpu_base = &per_cpu(hrtimer_bases, cpu);
967 : raw_spin_lock_irqsave(&cpu_base->lock, flags);
968 :
969 : if (update_needs_ipi(cpu_base, bases))
970 : cpumask_set_cpu(cpu, mask);
971 :
972 : raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
973 : }
974 :
975 : preempt_disable();
976 : smp_call_function_many(mask, retrigger_next_event, NULL, 1);
977 : preempt_enable();
978 : cpus_read_unlock();
979 : free_cpumask_var(mask);
980 :
981 : out_timerfd:
982 0 : timerfd_clock_was_set();
983 0 : }
984 :
985 0 : static void clock_was_set_work(struct work_struct *work)
986 : {
987 0 : clock_was_set(CLOCK_SET_WALL);
988 0 : }
989 :
990 : static DECLARE_WORK(hrtimer_work, clock_was_set_work);
991 :
992 : /*
993 : * Called from timekeeping code to reprogram the hrtimer interrupt device
994 : * on all cpus and to notify timerfd.
995 : */
996 0 : void clock_was_set_delayed(void)
997 : {
998 0 : schedule_work(&hrtimer_work);
999 0 : }
1000 :
1001 : /*
1002 : * Called during resume either directly from via timekeeping_resume()
1003 : * or in the case of s2idle from tick_unfreeze() to ensure that the
1004 : * hrtimers are up to date.
1005 : */
1006 0 : void hrtimers_resume_local(void)
1007 : {
1008 : lockdep_assert_irqs_disabled();
1009 : /* Retrigger on the local CPU */
1010 0 : retrigger_next_event(NULL);
1011 0 : }
1012 :
1013 : /*
1014 : * Counterpart to lock_hrtimer_base above:
1015 : */
1016 : static inline
1017 : void unlock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
1018 : __releases(&timer->base->cpu_base->lock)
1019 : {
1020 0 : raw_spin_unlock_irqrestore(&timer->base->cpu_base->lock, *flags);
1021 : }
1022 :
1023 : /**
1024 : * hrtimer_forward - forward the timer expiry
1025 : * @timer: hrtimer to forward
1026 : * @now: forward past this time
1027 : * @interval: the interval to forward
1028 : *
1029 : * Forward the timer expiry so it will expire in the future.
1030 : * Returns the number of overruns.
1031 : *
1032 : * Can be safely called from the callback function of @timer. If
1033 : * called from other contexts @timer must neither be enqueued nor
1034 : * running the callback and the caller needs to take care of
1035 : * serialization.
1036 : *
1037 : * Note: This only updates the timer expiry value and does not requeue
1038 : * the timer.
1039 : */
1040 0 : u64 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval)
1041 : {
1042 0 : u64 orun = 1;
1043 : ktime_t delta;
1044 :
1045 0 : delta = ktime_sub(now, hrtimer_get_expires(timer));
1046 :
1047 0 : if (delta < 0)
1048 : return 0;
1049 :
1050 0 : if (WARN_ON(timer->state & HRTIMER_STATE_ENQUEUED))
1051 : return 0;
1052 :
1053 0 : if (interval < hrtimer_resolution)
1054 0 : interval = hrtimer_resolution;
1055 :
1056 0 : if (unlikely(delta >= interval)) {
1057 0 : s64 incr = ktime_to_ns(interval);
1058 :
1059 0 : orun = ktime_divns(delta, incr);
1060 0 : hrtimer_add_expires_ns(timer, incr * orun);
1061 0 : if (hrtimer_get_expires_tv64(timer) > now)
1062 : return orun;
1063 : /*
1064 : * This (and the ktime_add() below) is the
1065 : * correction for exact:
1066 : */
1067 0 : orun++;
1068 : }
1069 0 : hrtimer_add_expires(timer, interval);
1070 :
1071 0 : return orun;
1072 : }
1073 : EXPORT_SYMBOL_GPL(hrtimer_forward);
1074 :
1075 : /*
1076 : * enqueue_hrtimer - internal function to (re)start a timer
1077 : *
1078 : * The timer is inserted in expiry order. Insertion into the
1079 : * red black tree is O(log(n)). Must hold the base lock.
1080 : *
1081 : * Returns 1 when the new timer is the leftmost timer in the tree.
1082 : */
1083 : static int enqueue_hrtimer(struct hrtimer *timer,
1084 : struct hrtimer_clock_base *base,
1085 : enum hrtimer_mode mode)
1086 : {
1087 0 : debug_activate(timer, mode);
1088 :
1089 0 : base->cpu_base->active_bases |= 1 << base->index;
1090 :
1091 : /* Pairs with the lockless read in hrtimer_is_queued() */
1092 0 : WRITE_ONCE(timer->state, HRTIMER_STATE_ENQUEUED);
1093 :
1094 0 : return timerqueue_add(&base->active, &timer->node);
1095 : }
1096 :
1097 : /*
1098 : * __remove_hrtimer - internal function to remove a timer
1099 : *
1100 : * Caller must hold the base lock.
1101 : *
1102 : * High resolution timer mode reprograms the clock event device when the
1103 : * timer is the one which expires next. The caller can disable this by setting
1104 : * reprogram to zero. This is useful, when the context does a reprogramming
1105 : * anyway (e.g. timer interrupt)
1106 : */
1107 0 : static void __remove_hrtimer(struct hrtimer *timer,
1108 : struct hrtimer_clock_base *base,
1109 : u8 newstate, int reprogram)
1110 : {
1111 0 : struct hrtimer_cpu_base *cpu_base = base->cpu_base;
1112 0 : u8 state = timer->state;
1113 :
1114 : /* Pairs with the lockless read in hrtimer_is_queued() */
1115 0 : WRITE_ONCE(timer->state, newstate);
1116 0 : if (!(state & HRTIMER_STATE_ENQUEUED))
1117 : return;
1118 :
1119 0 : if (!timerqueue_del(&base->active, &timer->node))
1120 0 : cpu_base->active_bases &= ~(1 << base->index);
1121 :
1122 : /*
1123 : * Note: If reprogram is false we do not update
1124 : * cpu_base->next_timer. This happens when we remove the first
1125 : * timer on a remote cpu. No harm as we never dereference
1126 : * cpu_base->next_timer. So the worst thing what can happen is
1127 : * an superfluous call to hrtimer_force_reprogram() on the
1128 : * remote cpu later on if the same timer gets enqueued again.
1129 : */
1130 0 : if (reprogram && timer == cpu_base->next_timer)
1131 : hrtimer_force_reprogram(cpu_base, 1);
1132 : }
1133 :
1134 : /*
1135 : * remove hrtimer, called with base lock held
1136 : */
1137 : static inline int
1138 : remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base,
1139 : bool restart, bool keep_local)
1140 : {
1141 0 : u8 state = timer->state;
1142 :
1143 0 : if (state & HRTIMER_STATE_ENQUEUED) {
1144 : bool reprogram;
1145 :
1146 : /*
1147 : * Remove the timer and force reprogramming when high
1148 : * resolution mode is active and the timer is on the current
1149 : * CPU. If we remove a timer on another CPU, reprogramming is
1150 : * skipped. The interrupt event on this CPU is fired and
1151 : * reprogramming happens in the interrupt handler. This is a
1152 : * rare case and less expensive than a smp call.
1153 : */
1154 0 : debug_deactivate(timer);
1155 0 : reprogram = base->cpu_base == this_cpu_ptr(&hrtimer_bases);
1156 :
1157 : /*
1158 : * If the timer is not restarted then reprogramming is
1159 : * required if the timer is local. If it is local and about
1160 : * to be restarted, avoid programming it twice (on removal
1161 : * and a moment later when it's requeued).
1162 : */
1163 : if (!restart)
1164 : state = HRTIMER_STATE_INACTIVE;
1165 : else
1166 0 : reprogram &= !keep_local;
1167 :
1168 0 : __remove_hrtimer(timer, base, state, reprogram);
1169 : return 1;
1170 : }
1171 : return 0;
1172 : }
1173 :
1174 : static inline ktime_t hrtimer_update_lowres(struct hrtimer *timer, ktime_t tim,
1175 : const enum hrtimer_mode mode)
1176 : {
1177 : #ifdef CONFIG_TIME_LOW_RES
1178 : /*
1179 : * CONFIG_TIME_LOW_RES indicates that the system has no way to return
1180 : * granular time values. For relative timers we add hrtimer_resolution
1181 : * (i.e. one jiffie) to prevent short timeouts.
1182 : */
1183 : timer->is_rel = mode & HRTIMER_MODE_REL;
1184 : if (timer->is_rel)
1185 : tim = ktime_add_safe(tim, hrtimer_resolution);
1186 : #endif
1187 : return tim;
1188 : }
1189 :
1190 : static void
1191 0 : hrtimer_update_softirq_timer(struct hrtimer_cpu_base *cpu_base, bool reprogram)
1192 : {
1193 : ktime_t expires;
1194 :
1195 : /*
1196 : * Find the next SOFT expiration.
1197 : */
1198 0 : expires = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_SOFT);
1199 :
1200 : /*
1201 : * reprogramming needs to be triggered, even if the next soft
1202 : * hrtimer expires at the same time than the next hard
1203 : * hrtimer. cpu_base->softirq_expires_next needs to be updated!
1204 : */
1205 0 : if (expires == KTIME_MAX)
1206 : return;
1207 :
1208 : /*
1209 : * cpu_base->*next_timer is recomputed by __hrtimer_get_next_event()
1210 : * cpu_base->*expires_next is only set by hrtimer_reprogram()
1211 : */
1212 0 : hrtimer_reprogram(cpu_base->softirq_next_timer, reprogram);
1213 : }
1214 :
1215 0 : static int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
1216 : u64 delta_ns, const enum hrtimer_mode mode,
1217 : struct hrtimer_clock_base *base)
1218 : {
1219 : struct hrtimer_clock_base *new_base;
1220 : bool force_local, first;
1221 :
1222 : /*
1223 : * If the timer is on the local cpu base and is the first expiring
1224 : * timer then this might end up reprogramming the hardware twice
1225 : * (on removal and on enqueue). To avoid that by prevent the
1226 : * reprogram on removal, keep the timer local to the current CPU
1227 : * and enforce reprogramming after it is queued no matter whether
1228 : * it is the new first expiring timer again or not.
1229 : */
1230 0 : force_local = base->cpu_base == this_cpu_ptr(&hrtimer_bases);
1231 0 : force_local &= base->cpu_base->next_timer == timer;
1232 :
1233 : /*
1234 : * Remove an active timer from the queue. In case it is not queued
1235 : * on the current CPU, make sure that remove_hrtimer() updates the
1236 : * remote data correctly.
1237 : *
1238 : * If it's on the current CPU and the first expiring timer, then
1239 : * skip reprogramming, keep the timer local and enforce
1240 : * reprogramming later if it was the first expiring timer. This
1241 : * avoids programming the underlying clock event twice (once at
1242 : * removal and once after enqueue).
1243 : */
1244 0 : remove_hrtimer(timer, base, true, force_local);
1245 :
1246 0 : if (mode & HRTIMER_MODE_REL)
1247 0 : tim = ktime_add_safe(tim, base->get_time());
1248 :
1249 0 : tim = hrtimer_update_lowres(timer, tim, mode);
1250 :
1251 0 : hrtimer_set_expires_range_ns(timer, tim, delta_ns);
1252 :
1253 : /* Switch the timer base, if necessary: */
1254 : if (!force_local) {
1255 : new_base = switch_hrtimer_base(timer, base,
1256 : mode & HRTIMER_MODE_PINNED);
1257 : } else {
1258 : new_base = base;
1259 : }
1260 :
1261 0 : first = enqueue_hrtimer(timer, new_base, mode);
1262 0 : if (!force_local)
1263 : return first;
1264 :
1265 : /*
1266 : * Timer was forced to stay on the current CPU to avoid
1267 : * reprogramming on removal and enqueue. Force reprogram the
1268 : * hardware by evaluating the new first expiring timer.
1269 : */
1270 0 : hrtimer_force_reprogram(new_base->cpu_base, 1);
1271 : return 0;
1272 : }
1273 :
1274 : /**
1275 : * hrtimer_start_range_ns - (re)start an hrtimer
1276 : * @timer: the timer to be added
1277 : * @tim: expiry time
1278 : * @delta_ns: "slack" range for the timer
1279 : * @mode: timer mode: absolute (HRTIMER_MODE_ABS) or
1280 : * relative (HRTIMER_MODE_REL), and pinned (HRTIMER_MODE_PINNED);
1281 : * softirq based mode is considered for debug purpose only!
1282 : */
1283 0 : void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
1284 : u64 delta_ns, const enum hrtimer_mode mode)
1285 : {
1286 : struct hrtimer_clock_base *base;
1287 : unsigned long flags;
1288 :
1289 : /*
1290 : * Check whether the HRTIMER_MODE_SOFT bit and hrtimer.is_soft
1291 : * match on CONFIG_PREEMPT_RT = n. With PREEMPT_RT check the hard
1292 : * expiry mode because unmarked timers are moved to softirq expiry.
1293 : */
1294 : if (!IS_ENABLED(CONFIG_PREEMPT_RT))
1295 0 : WARN_ON_ONCE(!(mode & HRTIMER_MODE_SOFT) ^ !timer->is_soft);
1296 : else
1297 : WARN_ON_ONCE(!(mode & HRTIMER_MODE_HARD) ^ !timer->is_hard);
1298 :
1299 0 : base = lock_hrtimer_base(timer, &flags);
1300 :
1301 0 : if (__hrtimer_start_range_ns(timer, tim, delta_ns, mode, base))
1302 0 : hrtimer_reprogram(timer, true);
1303 :
1304 0 : unlock_hrtimer_base(timer, &flags);
1305 0 : }
1306 : EXPORT_SYMBOL_GPL(hrtimer_start_range_ns);
1307 :
1308 : /**
1309 : * hrtimer_try_to_cancel - try to deactivate a timer
1310 : * @timer: hrtimer to stop
1311 : *
1312 : * Returns:
1313 : *
1314 : * * 0 when the timer was not active
1315 : * * 1 when the timer was active
1316 : * * -1 when the timer is currently executing the callback function and
1317 : * cannot be stopped
1318 : */
1319 160 : int hrtimer_try_to_cancel(struct hrtimer *timer)
1320 : {
1321 : struct hrtimer_clock_base *base;
1322 : unsigned long flags;
1323 160 : int ret = -1;
1324 :
1325 : /*
1326 : * Check lockless first. If the timer is not active (neither
1327 : * enqueued nor running the callback, nothing to do here. The
1328 : * base lock does not serialize against a concurrent enqueue,
1329 : * so we can avoid taking it.
1330 : */
1331 160 : if (!hrtimer_active(timer))
1332 : return 0;
1333 :
1334 0 : base = lock_hrtimer_base(timer, &flags);
1335 :
1336 0 : if (!hrtimer_callback_running(timer))
1337 : ret = remove_hrtimer(timer, base, false, false);
1338 :
1339 0 : unlock_hrtimer_base(timer, &flags);
1340 :
1341 0 : return ret;
1342 :
1343 : }
1344 : EXPORT_SYMBOL_GPL(hrtimer_try_to_cancel);
1345 :
1346 : #ifdef CONFIG_PREEMPT_RT
1347 : static void hrtimer_cpu_base_init_expiry_lock(struct hrtimer_cpu_base *base)
1348 : {
1349 : spin_lock_init(&base->softirq_expiry_lock);
1350 : }
1351 :
1352 : static void hrtimer_cpu_base_lock_expiry(struct hrtimer_cpu_base *base)
1353 : {
1354 : spin_lock(&base->softirq_expiry_lock);
1355 : }
1356 :
1357 : static void hrtimer_cpu_base_unlock_expiry(struct hrtimer_cpu_base *base)
1358 : {
1359 : spin_unlock(&base->softirq_expiry_lock);
1360 : }
1361 :
1362 : /*
1363 : * The counterpart to hrtimer_cancel_wait_running().
1364 : *
1365 : * If there is a waiter for cpu_base->expiry_lock, then it was waiting for
1366 : * the timer callback to finish. Drop expiry_lock and reacquire it. That
1367 : * allows the waiter to acquire the lock and make progress.
1368 : */
1369 : static void hrtimer_sync_wait_running(struct hrtimer_cpu_base *cpu_base,
1370 : unsigned long flags)
1371 : {
1372 : if (atomic_read(&cpu_base->timer_waiters)) {
1373 : raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1374 : spin_unlock(&cpu_base->softirq_expiry_lock);
1375 : spin_lock(&cpu_base->softirq_expiry_lock);
1376 : raw_spin_lock_irq(&cpu_base->lock);
1377 : }
1378 : }
1379 :
1380 : /*
1381 : * This function is called on PREEMPT_RT kernels when the fast path
1382 : * deletion of a timer failed because the timer callback function was
1383 : * running.
1384 : *
1385 : * This prevents priority inversion: if the soft irq thread is preempted
1386 : * in the middle of a timer callback, then calling del_timer_sync() can
1387 : * lead to two issues:
1388 : *
1389 : * - If the caller is on a remote CPU then it has to spin wait for the timer
1390 : * handler to complete. This can result in unbound priority inversion.
1391 : *
1392 : * - If the caller originates from the task which preempted the timer
1393 : * handler on the same CPU, then spin waiting for the timer handler to
1394 : * complete is never going to end.
1395 : */
1396 : void hrtimer_cancel_wait_running(const struct hrtimer *timer)
1397 : {
1398 : /* Lockless read. Prevent the compiler from reloading it below */
1399 : struct hrtimer_clock_base *base = READ_ONCE(timer->base);
1400 :
1401 : /*
1402 : * Just relax if the timer expires in hard interrupt context or if
1403 : * it is currently on the migration base.
1404 : */
1405 : if (!timer->is_soft || is_migration_base(base)) {
1406 : cpu_relax();
1407 : return;
1408 : }
1409 :
1410 : /*
1411 : * Mark the base as contended and grab the expiry lock, which is
1412 : * held by the softirq across the timer callback. Drop the lock
1413 : * immediately so the softirq can expire the next timer. In theory
1414 : * the timer could already be running again, but that's more than
1415 : * unlikely and just causes another wait loop.
1416 : */
1417 : atomic_inc(&base->cpu_base->timer_waiters);
1418 : spin_lock_bh(&base->cpu_base->softirq_expiry_lock);
1419 : atomic_dec(&base->cpu_base->timer_waiters);
1420 : spin_unlock_bh(&base->cpu_base->softirq_expiry_lock);
1421 : }
1422 : #else
1423 : static inline void
1424 : hrtimer_cpu_base_init_expiry_lock(struct hrtimer_cpu_base *base) { }
1425 : static inline void
1426 : hrtimer_cpu_base_lock_expiry(struct hrtimer_cpu_base *base) { }
1427 : static inline void
1428 : hrtimer_cpu_base_unlock_expiry(struct hrtimer_cpu_base *base) { }
1429 : static inline void hrtimer_sync_wait_running(struct hrtimer_cpu_base *base,
1430 : unsigned long flags) { }
1431 : #endif
1432 :
1433 : /**
1434 : * hrtimer_cancel - cancel a timer and wait for the handler to finish.
1435 : * @timer: the timer to be cancelled
1436 : *
1437 : * Returns:
1438 : * 0 when the timer was not active
1439 : * 1 when the timer was active
1440 : */
1441 160 : int hrtimer_cancel(struct hrtimer *timer)
1442 : {
1443 : int ret;
1444 :
1445 : do {
1446 160 : ret = hrtimer_try_to_cancel(timer);
1447 :
1448 160 : if (ret < 0)
1449 0 : hrtimer_cancel_wait_running(timer);
1450 160 : } while (ret < 0);
1451 160 : return ret;
1452 : }
1453 : EXPORT_SYMBOL_GPL(hrtimer_cancel);
1454 :
1455 : /**
1456 : * __hrtimer_get_remaining - get remaining time for the timer
1457 : * @timer: the timer to read
1458 : * @adjust: adjust relative timers when CONFIG_TIME_LOW_RES=y
1459 : */
1460 0 : ktime_t __hrtimer_get_remaining(const struct hrtimer *timer, bool adjust)
1461 : {
1462 : unsigned long flags;
1463 : ktime_t rem;
1464 :
1465 0 : lock_hrtimer_base(timer, &flags);
1466 : if (IS_ENABLED(CONFIG_TIME_LOW_RES) && adjust)
1467 : rem = hrtimer_expires_remaining_adjusted(timer);
1468 : else
1469 0 : rem = hrtimer_expires_remaining(timer);
1470 0 : unlock_hrtimer_base(timer, &flags);
1471 :
1472 0 : return rem;
1473 : }
1474 : EXPORT_SYMBOL_GPL(__hrtimer_get_remaining);
1475 :
1476 : #ifdef CONFIG_NO_HZ_COMMON
1477 : /**
1478 : * hrtimer_get_next_event - get the time until next expiry event
1479 : *
1480 : * Returns the next expiry time or KTIME_MAX if no timer is pending.
1481 : */
1482 : u64 hrtimer_get_next_event(void)
1483 : {
1484 : struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1485 : u64 expires = KTIME_MAX;
1486 : unsigned long flags;
1487 :
1488 : raw_spin_lock_irqsave(&cpu_base->lock, flags);
1489 :
1490 : if (!__hrtimer_hres_active(cpu_base))
1491 : expires = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_ALL);
1492 :
1493 : raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1494 :
1495 : return expires;
1496 : }
1497 :
1498 : /**
1499 : * hrtimer_next_event_without - time until next expiry event w/o one timer
1500 : * @exclude: timer to exclude
1501 : *
1502 : * Returns the next expiry time over all timers except for the @exclude one or
1503 : * KTIME_MAX if none of them is pending.
1504 : */
1505 : u64 hrtimer_next_event_without(const struct hrtimer *exclude)
1506 : {
1507 : struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1508 : u64 expires = KTIME_MAX;
1509 : unsigned long flags;
1510 :
1511 : raw_spin_lock_irqsave(&cpu_base->lock, flags);
1512 :
1513 : if (__hrtimer_hres_active(cpu_base)) {
1514 : unsigned int active;
1515 :
1516 : if (!cpu_base->softirq_activated) {
1517 : active = cpu_base->active_bases & HRTIMER_ACTIVE_SOFT;
1518 : expires = __hrtimer_next_event_base(cpu_base, exclude,
1519 : active, KTIME_MAX);
1520 : }
1521 : active = cpu_base->active_bases & HRTIMER_ACTIVE_HARD;
1522 : expires = __hrtimer_next_event_base(cpu_base, exclude, active,
1523 : expires);
1524 : }
1525 :
1526 : raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1527 :
1528 : return expires;
1529 : }
1530 : #endif
1531 :
1532 1073 : static inline int hrtimer_clockid_to_base(clockid_t clock_id)
1533 : {
1534 1073 : if (likely(clock_id < MAX_CLOCKS)) {
1535 1073 : int base = hrtimer_clock_to_base_table[clock_id];
1536 :
1537 1073 : if (likely(base != HRTIMER_MAX_CLOCK_BASES))
1538 : return base;
1539 : }
1540 0 : WARN(1, "Invalid clockid %d. Using MONOTONIC\n", clock_id);
1541 0 : return HRTIMER_BASE_MONOTONIC;
1542 : }
1543 :
1544 1073 : static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
1545 : enum hrtimer_mode mode)
1546 : {
1547 1073 : bool softtimer = !!(mode & HRTIMER_MODE_SOFT);
1548 : struct hrtimer_cpu_base *cpu_base;
1549 : int base;
1550 :
1551 : /*
1552 : * On PREEMPT_RT enabled kernels hrtimers which are not explicitly
1553 : * marked for hard interrupt expiry mode are moved into soft
1554 : * interrupt context for latency reasons and because the callbacks
1555 : * can invoke functions which might sleep on RT, e.g. spin_lock().
1556 : */
1557 : if (IS_ENABLED(CONFIG_PREEMPT_RT) && !(mode & HRTIMER_MODE_HARD))
1558 : softtimer = true;
1559 :
1560 2146 : memset(timer, 0, sizeof(struct hrtimer));
1561 :
1562 1073 : cpu_base = raw_cpu_ptr(&hrtimer_bases);
1563 :
1564 : /*
1565 : * POSIX magic: Relative CLOCK_REALTIME timers are not affected by
1566 : * clock modifications, so they needs to become CLOCK_MONOTONIC to
1567 : * ensure POSIX compliance.
1568 : */
1569 1073 : if (clock_id == CLOCK_REALTIME && mode & HRTIMER_MODE_REL)
1570 0 : clock_id = CLOCK_MONOTONIC;
1571 :
1572 1073 : base = softtimer ? HRTIMER_MAX_CLOCK_BASES / 2 : 0;
1573 1073 : base += hrtimer_clockid_to_base(clock_id);
1574 1073 : timer->is_soft = softtimer;
1575 1073 : timer->is_hard = !!(mode & HRTIMER_MODE_HARD);
1576 1073 : timer->base = &cpu_base->clock_base[base];
1577 2146 : timerqueue_init(&timer->node);
1578 1073 : }
1579 :
1580 : /**
1581 : * hrtimer_init - initialize a timer to the given clock
1582 : * @timer: the timer to be initialized
1583 : * @clock_id: the clock to be used
1584 : * @mode: The modes which are relevant for initialization:
1585 : * HRTIMER_MODE_ABS, HRTIMER_MODE_REL, HRTIMER_MODE_ABS_SOFT,
1586 : * HRTIMER_MODE_REL_SOFT
1587 : *
1588 : * The PINNED variants of the above can be handed in,
1589 : * but the PINNED bit is ignored as pinning happens
1590 : * when the hrtimer is started
1591 : */
1592 1073 : void hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
1593 : enum hrtimer_mode mode)
1594 : {
1595 1073 : debug_init(timer, clock_id, mode);
1596 1073 : __hrtimer_init(timer, clock_id, mode);
1597 1073 : }
1598 : EXPORT_SYMBOL_GPL(hrtimer_init);
1599 :
1600 : /*
1601 : * A timer is active, when it is enqueued into the rbtree or the
1602 : * callback function is running or it's in the state of being migrated
1603 : * to another cpu.
1604 : *
1605 : * It is important for this function to not return a false negative.
1606 : */
1607 160 : bool hrtimer_active(const struct hrtimer *timer)
1608 : {
1609 : struct hrtimer_clock_base *base;
1610 : unsigned int seq;
1611 :
1612 : do {
1613 160 : base = READ_ONCE(timer->base);
1614 480 : seq = raw_read_seqcount_begin(&base->seq);
1615 :
1616 320 : if (timer->state != HRTIMER_STATE_INACTIVE ||
1617 160 : base->running == timer)
1618 : return true;
1619 :
1620 640 : } while (read_seqcount_retry(&base->seq, seq) ||
1621 160 : base != READ_ONCE(timer->base));
1622 :
1623 : return false;
1624 : }
1625 : EXPORT_SYMBOL_GPL(hrtimer_active);
1626 :
1627 : /*
1628 : * The write_seqcount_barrier()s in __run_hrtimer() split the thing into 3
1629 : * distinct sections:
1630 : *
1631 : * - queued: the timer is queued
1632 : * - callback: the timer is being ran
1633 : * - post: the timer is inactive or (re)queued
1634 : *
1635 : * On the read side we ensure we observe timer->state and cpu_base->running
1636 : * from the same section, if anything changed while we looked at it, we retry.
1637 : * This includes timer->base changing because sequence numbers alone are
1638 : * insufficient for that.
1639 : *
1640 : * The sequence numbers are required because otherwise we could still observe
1641 : * a false negative if the read side got smeared over multiple consecutive
1642 : * __run_hrtimer() invocations.
1643 : */
1644 :
1645 0 : static void __run_hrtimer(struct hrtimer_cpu_base *cpu_base,
1646 : struct hrtimer_clock_base *base,
1647 : struct hrtimer *timer, ktime_t *now,
1648 : unsigned long flags) __must_hold(&cpu_base->lock)
1649 : {
1650 : enum hrtimer_restart (*fn)(struct hrtimer *);
1651 : bool expires_in_hardirq;
1652 : int restart;
1653 :
1654 : lockdep_assert_held(&cpu_base->lock);
1655 :
1656 0 : debug_deactivate(timer);
1657 0 : base->running = timer;
1658 :
1659 : /*
1660 : * Separate the ->running assignment from the ->state assignment.
1661 : *
1662 : * As with a regular write barrier, this ensures the read side in
1663 : * hrtimer_active() cannot observe base->running == NULL &&
1664 : * timer->state == INACTIVE.
1665 : */
1666 0 : raw_write_seqcount_barrier(&base->seq);
1667 :
1668 0 : __remove_hrtimer(timer, base, HRTIMER_STATE_INACTIVE, 0);
1669 0 : fn = timer->function;
1670 :
1671 : /*
1672 : * Clear the 'is relative' flag for the TIME_LOW_RES case. If the
1673 : * timer is restarted with a period then it becomes an absolute
1674 : * timer. If its not restarted it does not matter.
1675 : */
1676 : if (IS_ENABLED(CONFIG_TIME_LOW_RES))
1677 : timer->is_rel = false;
1678 :
1679 : /*
1680 : * The timer is marked as running in the CPU base, so it is
1681 : * protected against migration to a different CPU even if the lock
1682 : * is dropped.
1683 : */
1684 0 : raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1685 0 : trace_hrtimer_expire_entry(timer, now);
1686 0 : expires_in_hardirq = lockdep_hrtimer_enter(timer);
1687 :
1688 0 : restart = fn(timer);
1689 :
1690 : lockdep_hrtimer_exit(expires_in_hardirq);
1691 0 : trace_hrtimer_expire_exit(timer);
1692 0 : raw_spin_lock_irq(&cpu_base->lock);
1693 :
1694 : /*
1695 : * Note: We clear the running state after enqueue_hrtimer and
1696 : * we do not reprogram the event hardware. Happens either in
1697 : * hrtimer_start_range_ns() or in hrtimer_interrupt()
1698 : *
1699 : * Note: Because we dropped the cpu_base->lock above,
1700 : * hrtimer_start_range_ns() can have popped in and enqueued the timer
1701 : * for us already.
1702 : */
1703 0 : if (restart != HRTIMER_NORESTART &&
1704 0 : !(timer->state & HRTIMER_STATE_ENQUEUED))
1705 0 : enqueue_hrtimer(timer, base, HRTIMER_MODE_ABS);
1706 :
1707 : /*
1708 : * Separate the ->running assignment from the ->state assignment.
1709 : *
1710 : * As with a regular write barrier, this ensures the read side in
1711 : * hrtimer_active() cannot observe base->running.timer == NULL &&
1712 : * timer->state == INACTIVE.
1713 : */
1714 0 : raw_write_seqcount_barrier(&base->seq);
1715 :
1716 0 : WARN_ON_ONCE(base->running != timer);
1717 0 : base->running = NULL;
1718 0 : }
1719 :
1720 5 : static void __hrtimer_run_queues(struct hrtimer_cpu_base *cpu_base, ktime_t now,
1721 : unsigned long flags, unsigned int active_mask)
1722 : {
1723 : struct hrtimer_clock_base *base;
1724 5 : unsigned int active = cpu_base->active_bases & active_mask;
1725 :
1726 10 : for_each_active_base(base, cpu_base, active) {
1727 : struct timerqueue_node *node;
1728 : ktime_t basenow;
1729 :
1730 0 : basenow = ktime_add(now, base->offset);
1731 :
1732 0 : while ((node = timerqueue_getnext(&base->active))) {
1733 : struct hrtimer *timer;
1734 :
1735 0 : timer = container_of(node, struct hrtimer, node);
1736 :
1737 : /*
1738 : * The immediate goal for using the softexpires is
1739 : * minimizing wakeups, not running timers at the
1740 : * earliest interrupt after their soft expiration.
1741 : * This allows us to avoid using a Priority Search
1742 : * Tree, which can answer a stabbing query for
1743 : * overlapping intervals and instead use the simple
1744 : * BST we already have.
1745 : * We don't add extra wakeups by delaying timers that
1746 : * are right-of a not yet expired timer, because that
1747 : * timer will have to trigger a wakeup anyway.
1748 : */
1749 0 : if (basenow < hrtimer_get_softexpires_tv64(timer))
1750 : break;
1751 :
1752 0 : __run_hrtimer(cpu_base, base, timer, &basenow, flags);
1753 : if (active_mask == HRTIMER_ACTIVE_SOFT)
1754 : hrtimer_sync_wait_running(cpu_base, flags);
1755 : }
1756 : }
1757 5 : }
1758 :
1759 0 : static __latent_entropy void hrtimer_run_softirq(struct softirq_action *h)
1760 : {
1761 0 : struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1762 : unsigned long flags;
1763 : ktime_t now;
1764 :
1765 0 : hrtimer_cpu_base_lock_expiry(cpu_base);
1766 0 : raw_spin_lock_irqsave(&cpu_base->lock, flags);
1767 :
1768 0 : now = hrtimer_update_base(cpu_base);
1769 0 : __hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_SOFT);
1770 :
1771 0 : cpu_base->softirq_activated = 0;
1772 0 : hrtimer_update_softirq_timer(cpu_base, true);
1773 :
1774 0 : raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1775 0 : hrtimer_cpu_base_unlock_expiry(cpu_base);
1776 0 : }
1777 :
1778 : #ifdef CONFIG_HIGH_RES_TIMERS
1779 :
1780 : /*
1781 : * High resolution timer interrupt
1782 : * Called with interrupts disabled
1783 : */
1784 : void hrtimer_interrupt(struct clock_event_device *dev)
1785 : {
1786 : struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1787 : ktime_t expires_next, now, entry_time, delta;
1788 : unsigned long flags;
1789 : int retries = 0;
1790 :
1791 : BUG_ON(!cpu_base->hres_active);
1792 : cpu_base->nr_events++;
1793 : dev->next_event = KTIME_MAX;
1794 :
1795 : raw_spin_lock_irqsave(&cpu_base->lock, flags);
1796 : entry_time = now = hrtimer_update_base(cpu_base);
1797 : retry:
1798 : cpu_base->in_hrtirq = 1;
1799 : /*
1800 : * We set expires_next to KTIME_MAX here with cpu_base->lock
1801 : * held to prevent that a timer is enqueued in our queue via
1802 : * the migration code. This does not affect enqueueing of
1803 : * timers which run their callback and need to be requeued on
1804 : * this CPU.
1805 : */
1806 : cpu_base->expires_next = KTIME_MAX;
1807 :
1808 : if (!ktime_before(now, cpu_base->softirq_expires_next)) {
1809 : cpu_base->softirq_expires_next = KTIME_MAX;
1810 : cpu_base->softirq_activated = 1;
1811 : raise_softirq_irqoff(HRTIMER_SOFTIRQ);
1812 : }
1813 :
1814 : __hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_HARD);
1815 :
1816 : /* Reevaluate the clock bases for the [soft] next expiry */
1817 : expires_next = hrtimer_update_next_event(cpu_base);
1818 : /*
1819 : * Store the new expiry value so the migration code can verify
1820 : * against it.
1821 : */
1822 : cpu_base->expires_next = expires_next;
1823 : cpu_base->in_hrtirq = 0;
1824 : raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1825 :
1826 : /* Reprogramming necessary ? */
1827 : if (!tick_program_event(expires_next, 0)) {
1828 : cpu_base->hang_detected = 0;
1829 : return;
1830 : }
1831 :
1832 : /*
1833 : * The next timer was already expired due to:
1834 : * - tracing
1835 : * - long lasting callbacks
1836 : * - being scheduled away when running in a VM
1837 : *
1838 : * We need to prevent that we loop forever in the hrtimer
1839 : * interrupt routine. We give it 3 attempts to avoid
1840 : * overreacting on some spurious event.
1841 : *
1842 : * Acquire base lock for updating the offsets and retrieving
1843 : * the current time.
1844 : */
1845 : raw_spin_lock_irqsave(&cpu_base->lock, flags);
1846 : now = hrtimer_update_base(cpu_base);
1847 : cpu_base->nr_retries++;
1848 : if (++retries < 3)
1849 : goto retry;
1850 : /*
1851 : * Give the system a chance to do something else than looping
1852 : * here. We stored the entry time, so we know exactly how long
1853 : * we spent here. We schedule the next event this amount of
1854 : * time away.
1855 : */
1856 : cpu_base->nr_hangs++;
1857 : cpu_base->hang_detected = 1;
1858 : raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1859 :
1860 : delta = ktime_sub(now, entry_time);
1861 : if ((unsigned int)delta > cpu_base->max_hang_time)
1862 : cpu_base->max_hang_time = (unsigned int) delta;
1863 : /*
1864 : * Limit it to a sensible value as we enforce a longer
1865 : * delay. Give the CPU at least 100ms to catch up.
1866 : */
1867 : if (delta > 100 * NSEC_PER_MSEC)
1868 : expires_next = ktime_add_ns(now, 100 * NSEC_PER_MSEC);
1869 : else
1870 : expires_next = ktime_add(now, delta);
1871 : tick_program_event(expires_next, 1);
1872 : pr_warn_once("hrtimer: interrupt took %llu ns\n", ktime_to_ns(delta));
1873 : }
1874 :
1875 : /* called with interrupts disabled */
1876 : static inline void __hrtimer_peek_ahead_timers(void)
1877 : {
1878 : struct tick_device *td;
1879 :
1880 : if (!hrtimer_hres_active())
1881 : return;
1882 :
1883 : td = this_cpu_ptr(&tick_cpu_device);
1884 : if (td && td->evtdev)
1885 : hrtimer_interrupt(td->evtdev);
1886 : }
1887 :
1888 : #else /* CONFIG_HIGH_RES_TIMERS */
1889 :
1890 : static inline void __hrtimer_peek_ahead_timers(void) { }
1891 :
1892 : #endif /* !CONFIG_HIGH_RES_TIMERS */
1893 :
1894 : /*
1895 : * Called from run_local_timers in hardirq context every jiffy
1896 : */
1897 5 : void hrtimer_run_queues(void)
1898 : {
1899 5 : struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1900 : unsigned long flags;
1901 : ktime_t now;
1902 :
1903 5 : if (__hrtimer_hres_active(cpu_base))
1904 : return;
1905 :
1906 : /*
1907 : * This _is_ ugly: We have to check periodically, whether we
1908 : * can switch to highres and / or nohz mode. The clocksource
1909 : * switch happens with xtime_lock held. Notification from
1910 : * there only sets the check bit in the tick_oneshot code,
1911 : * otherwise we might deadlock vs. xtime_lock.
1912 : */
1913 5 : if (tick_check_oneshot_change(!hrtimer_is_hres_enabled())) {
1914 : hrtimer_switch_to_hres();
1915 : return;
1916 : }
1917 :
1918 5 : raw_spin_lock_irqsave(&cpu_base->lock, flags);
1919 5 : now = hrtimer_update_base(cpu_base);
1920 :
1921 10 : if (!ktime_before(now, cpu_base->softirq_expires_next)) {
1922 0 : cpu_base->softirq_expires_next = KTIME_MAX;
1923 0 : cpu_base->softirq_activated = 1;
1924 0 : raise_softirq_irqoff(HRTIMER_SOFTIRQ);
1925 : }
1926 :
1927 5 : __hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_HARD);
1928 10 : raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1929 : }
1930 :
1931 : /*
1932 : * Sleep related functions:
1933 : */
1934 0 : static enum hrtimer_restart hrtimer_wakeup(struct hrtimer *timer)
1935 : {
1936 0 : struct hrtimer_sleeper *t =
1937 0 : container_of(timer, struct hrtimer_sleeper, timer);
1938 0 : struct task_struct *task = t->task;
1939 :
1940 0 : t->task = NULL;
1941 0 : if (task)
1942 0 : wake_up_process(task);
1943 :
1944 0 : return HRTIMER_NORESTART;
1945 : }
1946 :
1947 : /**
1948 : * hrtimer_sleeper_start_expires - Start a hrtimer sleeper timer
1949 : * @sl: sleeper to be started
1950 : * @mode: timer mode abs/rel
1951 : *
1952 : * Wrapper around hrtimer_start_expires() for hrtimer_sleeper based timers
1953 : * to allow PREEMPT_RT to tweak the delivery mode (soft/hardirq context)
1954 : */
1955 0 : void hrtimer_sleeper_start_expires(struct hrtimer_sleeper *sl,
1956 : enum hrtimer_mode mode)
1957 : {
1958 : /*
1959 : * Make the enqueue delivery mode check work on RT. If the sleeper
1960 : * was initialized for hard interrupt delivery, force the mode bit.
1961 : * This is a special case for hrtimer_sleepers because
1962 : * hrtimer_init_sleeper() determines the delivery mode on RT so the
1963 : * fiddling with this decision is avoided at the call sites.
1964 : */
1965 : if (IS_ENABLED(CONFIG_PREEMPT_RT) && sl->timer.is_hard)
1966 : mode |= HRTIMER_MODE_HARD;
1967 :
1968 0 : hrtimer_start_expires(&sl->timer, mode);
1969 0 : }
1970 : EXPORT_SYMBOL_GPL(hrtimer_sleeper_start_expires);
1971 :
1972 : static void __hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
1973 : clockid_t clock_id, enum hrtimer_mode mode)
1974 : {
1975 : /*
1976 : * On PREEMPT_RT enabled kernels hrtimers which are not explicitly
1977 : * marked for hard interrupt expiry mode are moved into soft
1978 : * interrupt context either for latency reasons or because the
1979 : * hrtimer callback takes regular spinlocks or invokes other
1980 : * functions which are not suitable for hard interrupt context on
1981 : * PREEMPT_RT.
1982 : *
1983 : * The hrtimer_sleeper callback is RT compatible in hard interrupt
1984 : * context, but there is a latency concern: Untrusted userspace can
1985 : * spawn many threads which arm timers for the same expiry time on
1986 : * the same CPU. That causes a latency spike due to the wakeup of
1987 : * a gazillion threads.
1988 : *
1989 : * OTOH, privileged real-time user space applications rely on the
1990 : * low latency of hard interrupt wakeups. If the current task is in
1991 : * a real-time scheduling class, mark the mode for hard interrupt
1992 : * expiry.
1993 : */
1994 : if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
1995 : if (task_is_realtime(current) && !(mode & HRTIMER_MODE_SOFT))
1996 : mode |= HRTIMER_MODE_HARD;
1997 : }
1998 :
1999 0 : __hrtimer_init(&sl->timer, clock_id, mode);
2000 0 : sl->timer.function = hrtimer_wakeup;
2001 0 : sl->task = current;
2002 : }
2003 :
2004 : /**
2005 : * hrtimer_init_sleeper - initialize sleeper to the given clock
2006 : * @sl: sleeper to be initialized
2007 : * @clock_id: the clock to be used
2008 : * @mode: timer mode abs/rel
2009 : */
2010 0 : void hrtimer_init_sleeper(struct hrtimer_sleeper *sl, clockid_t clock_id,
2011 : enum hrtimer_mode mode)
2012 : {
2013 0 : debug_init(&sl->timer, clock_id, mode);
2014 0 : __hrtimer_init_sleeper(sl, clock_id, mode);
2015 :
2016 0 : }
2017 : EXPORT_SYMBOL_GPL(hrtimer_init_sleeper);
2018 :
2019 0 : int nanosleep_copyout(struct restart_block *restart, struct timespec64 *ts)
2020 : {
2021 0 : switch(restart->nanosleep.type) {
2022 : #ifdef CONFIG_COMPAT_32BIT_TIME
2023 : case TT_COMPAT:
2024 : if (put_old_timespec32(ts, restart->nanosleep.compat_rmtp))
2025 : return -EFAULT;
2026 : break;
2027 : #endif
2028 : case TT_NATIVE:
2029 0 : if (put_timespec64(ts, restart->nanosleep.rmtp))
2030 : return -EFAULT;
2031 : break;
2032 : default:
2033 0 : BUG();
2034 : }
2035 0 : return -ERESTART_RESTARTBLOCK;
2036 : }
2037 :
2038 0 : static int __sched do_nanosleep(struct hrtimer_sleeper *t, enum hrtimer_mode mode)
2039 : {
2040 : struct restart_block *restart;
2041 :
2042 : do {
2043 0 : set_current_state(TASK_INTERRUPTIBLE|TASK_FREEZABLE);
2044 0 : hrtimer_sleeper_start_expires(t, mode);
2045 :
2046 0 : if (likely(t->task))
2047 0 : schedule();
2048 :
2049 0 : hrtimer_cancel(&t->timer);
2050 0 : mode = HRTIMER_MODE_ABS;
2051 :
2052 0 : } while (t->task && !signal_pending(current));
2053 :
2054 0 : __set_current_state(TASK_RUNNING);
2055 :
2056 0 : if (!t->task)
2057 : return 0;
2058 :
2059 0 : restart = ¤t->restart_block;
2060 0 : if (restart->nanosleep.type != TT_NONE) {
2061 0 : ktime_t rem = hrtimer_expires_remaining(&t->timer);
2062 : struct timespec64 rmt;
2063 :
2064 0 : if (rem <= 0)
2065 : return 0;
2066 0 : rmt = ktime_to_timespec64(rem);
2067 :
2068 0 : return nanosleep_copyout(restart, &rmt);
2069 : }
2070 : return -ERESTART_RESTARTBLOCK;
2071 : }
2072 :
2073 0 : static long __sched hrtimer_nanosleep_restart(struct restart_block *restart)
2074 : {
2075 : struct hrtimer_sleeper t;
2076 : int ret;
2077 :
2078 0 : hrtimer_init_sleeper_on_stack(&t, restart->nanosleep.clockid,
2079 : HRTIMER_MODE_ABS);
2080 0 : hrtimer_set_expires_tv64(&t.timer, restart->nanosleep.expires);
2081 0 : ret = do_nanosleep(&t, HRTIMER_MODE_ABS);
2082 0 : destroy_hrtimer_on_stack(&t.timer);
2083 0 : return ret;
2084 : }
2085 :
2086 0 : long hrtimer_nanosleep(ktime_t rqtp, const enum hrtimer_mode mode,
2087 : const clockid_t clockid)
2088 : {
2089 : struct restart_block *restart;
2090 : struct hrtimer_sleeper t;
2091 0 : int ret = 0;
2092 : u64 slack;
2093 :
2094 0 : slack = current->timer_slack_ns;
2095 0 : if (rt_task(current))
2096 0 : slack = 0;
2097 :
2098 0 : hrtimer_init_sleeper_on_stack(&t, clockid, mode);
2099 0 : hrtimer_set_expires_range_ns(&t.timer, rqtp, slack);
2100 0 : ret = do_nanosleep(&t, mode);
2101 0 : if (ret != -ERESTART_RESTARTBLOCK)
2102 : goto out;
2103 :
2104 : /* Absolute timers do not update the rmtp value and restart: */
2105 0 : if (mode == HRTIMER_MODE_ABS) {
2106 : ret = -ERESTARTNOHAND;
2107 : goto out;
2108 : }
2109 :
2110 0 : restart = ¤t->restart_block;
2111 0 : restart->nanosleep.clockid = t.timer.base->clockid;
2112 0 : restart->nanosleep.expires = hrtimer_get_expires_tv64(&t.timer);
2113 0 : set_restart_fn(restart, hrtimer_nanosleep_restart);
2114 : out:
2115 0 : destroy_hrtimer_on_stack(&t.timer);
2116 0 : return ret;
2117 : }
2118 :
2119 : #ifdef CONFIG_64BIT
2120 :
2121 0 : SYSCALL_DEFINE2(nanosleep, struct __kernel_timespec __user *, rqtp,
2122 : struct __kernel_timespec __user *, rmtp)
2123 : {
2124 : struct timespec64 tu;
2125 :
2126 0 : if (get_timespec64(&tu, rqtp))
2127 : return -EFAULT;
2128 :
2129 0 : if (!timespec64_valid(&tu))
2130 : return -EINVAL;
2131 :
2132 0 : current->restart_block.fn = do_no_restart_syscall;
2133 0 : current->restart_block.nanosleep.type = rmtp ? TT_NATIVE : TT_NONE;
2134 0 : current->restart_block.nanosleep.rmtp = rmtp;
2135 0 : return hrtimer_nanosleep(timespec64_to_ktime(tu), HRTIMER_MODE_REL,
2136 : CLOCK_MONOTONIC);
2137 : }
2138 :
2139 : #endif
2140 :
2141 : #ifdef CONFIG_COMPAT_32BIT_TIME
2142 :
2143 : SYSCALL_DEFINE2(nanosleep_time32, struct old_timespec32 __user *, rqtp,
2144 : struct old_timespec32 __user *, rmtp)
2145 : {
2146 : struct timespec64 tu;
2147 :
2148 : if (get_old_timespec32(&tu, rqtp))
2149 : return -EFAULT;
2150 :
2151 : if (!timespec64_valid(&tu))
2152 : return -EINVAL;
2153 :
2154 : current->restart_block.fn = do_no_restart_syscall;
2155 : current->restart_block.nanosleep.type = rmtp ? TT_COMPAT : TT_NONE;
2156 : current->restart_block.nanosleep.compat_rmtp = rmtp;
2157 : return hrtimer_nanosleep(timespec64_to_ktime(tu), HRTIMER_MODE_REL,
2158 : CLOCK_MONOTONIC);
2159 : }
2160 : #endif
2161 :
2162 : /*
2163 : * Functions related to boot-time initialization:
2164 : */
2165 0 : int hrtimers_prepare_cpu(unsigned int cpu)
2166 : {
2167 1 : struct hrtimer_cpu_base *cpu_base = &per_cpu(hrtimer_bases, cpu);
2168 : int i;
2169 :
2170 9 : for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
2171 8 : struct hrtimer_clock_base *clock_b = &cpu_base->clock_base[i];
2172 :
2173 8 : clock_b->cpu_base = cpu_base;
2174 16 : seqcount_raw_spinlock_init(&clock_b->seq, &cpu_base->lock);
2175 16 : timerqueue_init_head(&clock_b->active);
2176 : }
2177 :
2178 1 : cpu_base->cpu = cpu;
2179 1 : cpu_base->active_bases = 0;
2180 1 : cpu_base->hres_active = 0;
2181 1 : cpu_base->hang_detected = 0;
2182 1 : cpu_base->next_timer = NULL;
2183 1 : cpu_base->softirq_next_timer = NULL;
2184 1 : cpu_base->expires_next = KTIME_MAX;
2185 1 : cpu_base->softirq_expires_next = KTIME_MAX;
2186 1 : hrtimer_cpu_base_init_expiry_lock(cpu_base);
2187 0 : return 0;
2188 : }
2189 :
2190 : #ifdef CONFIG_HOTPLUG_CPU
2191 :
2192 : static void migrate_hrtimer_list(struct hrtimer_clock_base *old_base,
2193 : struct hrtimer_clock_base *new_base)
2194 : {
2195 : struct hrtimer *timer;
2196 : struct timerqueue_node *node;
2197 :
2198 : while ((node = timerqueue_getnext(&old_base->active))) {
2199 : timer = container_of(node, struct hrtimer, node);
2200 : BUG_ON(hrtimer_callback_running(timer));
2201 : debug_deactivate(timer);
2202 :
2203 : /*
2204 : * Mark it as ENQUEUED not INACTIVE otherwise the
2205 : * timer could be seen as !active and just vanish away
2206 : * under us on another CPU
2207 : */
2208 : __remove_hrtimer(timer, old_base, HRTIMER_STATE_ENQUEUED, 0);
2209 : timer->base = new_base;
2210 : /*
2211 : * Enqueue the timers on the new cpu. This does not
2212 : * reprogram the event device in case the timer
2213 : * expires before the earliest on this CPU, but we run
2214 : * hrtimer_interrupt after we migrated everything to
2215 : * sort out already expired timers and reprogram the
2216 : * event device.
2217 : */
2218 : enqueue_hrtimer(timer, new_base, HRTIMER_MODE_ABS);
2219 : }
2220 : }
2221 :
2222 : int hrtimers_dead_cpu(unsigned int scpu)
2223 : {
2224 : struct hrtimer_cpu_base *old_base, *new_base;
2225 : int i;
2226 :
2227 : BUG_ON(cpu_online(scpu));
2228 : tick_cancel_sched_timer(scpu);
2229 :
2230 : /*
2231 : * this BH disable ensures that raise_softirq_irqoff() does
2232 : * not wakeup ksoftirqd (and acquire the pi-lock) while
2233 : * holding the cpu_base lock
2234 : */
2235 : local_bh_disable();
2236 : local_irq_disable();
2237 : old_base = &per_cpu(hrtimer_bases, scpu);
2238 : new_base = this_cpu_ptr(&hrtimer_bases);
2239 : /*
2240 : * The caller is globally serialized and nobody else
2241 : * takes two locks at once, deadlock is not possible.
2242 : */
2243 : raw_spin_lock(&new_base->lock);
2244 : raw_spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);
2245 :
2246 : for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
2247 : migrate_hrtimer_list(&old_base->clock_base[i],
2248 : &new_base->clock_base[i]);
2249 : }
2250 :
2251 : /*
2252 : * The migration might have changed the first expiring softirq
2253 : * timer on this CPU. Update it.
2254 : */
2255 : hrtimer_update_softirq_timer(new_base, false);
2256 :
2257 : raw_spin_unlock(&old_base->lock);
2258 : raw_spin_unlock(&new_base->lock);
2259 :
2260 : /* Check, if we got expired work to do */
2261 : __hrtimer_peek_ahead_timers();
2262 : local_irq_enable();
2263 : local_bh_enable();
2264 : return 0;
2265 : }
2266 :
2267 : #endif /* CONFIG_HOTPLUG_CPU */
2268 :
2269 1 : void __init hrtimers_init(void)
2270 : {
2271 1 : hrtimers_prepare_cpu(smp_processor_id());
2272 1 : open_softirq(HRTIMER_SOFTIRQ, hrtimer_run_softirq);
2273 1 : }
2274 :
2275 : /**
2276 : * schedule_hrtimeout_range_clock - sleep until timeout
2277 : * @expires: timeout value (ktime_t)
2278 : * @delta: slack in expires timeout (ktime_t) for SCHED_OTHER tasks
2279 : * @mode: timer mode
2280 : * @clock_id: timer clock to be used
2281 : */
2282 : int __sched
2283 0 : schedule_hrtimeout_range_clock(ktime_t *expires, u64 delta,
2284 : const enum hrtimer_mode mode, clockid_t clock_id)
2285 : {
2286 : struct hrtimer_sleeper t;
2287 :
2288 : /*
2289 : * Optimize when a zero timeout value is given. It does not
2290 : * matter whether this is an absolute or a relative time.
2291 : */
2292 0 : if (expires && *expires == 0) {
2293 0 : __set_current_state(TASK_RUNNING);
2294 0 : return 0;
2295 : }
2296 :
2297 : /*
2298 : * A NULL parameter means "infinite"
2299 : */
2300 0 : if (!expires) {
2301 0 : schedule();
2302 0 : return -EINTR;
2303 : }
2304 :
2305 : /*
2306 : * Override any slack passed by the user if under
2307 : * rt contraints.
2308 : */
2309 0 : if (rt_task(current))
2310 0 : delta = 0;
2311 :
2312 0 : hrtimer_init_sleeper_on_stack(&t, clock_id, mode);
2313 0 : hrtimer_set_expires_range_ns(&t.timer, *expires, delta);
2314 0 : hrtimer_sleeper_start_expires(&t, mode);
2315 :
2316 0 : if (likely(t.task))
2317 0 : schedule();
2318 :
2319 0 : hrtimer_cancel(&t.timer);
2320 0 : destroy_hrtimer_on_stack(&t.timer);
2321 :
2322 0 : __set_current_state(TASK_RUNNING);
2323 :
2324 0 : return !t.task ? 0 : -EINTR;
2325 : }
2326 : EXPORT_SYMBOL_GPL(schedule_hrtimeout_range_clock);
2327 :
2328 : /**
2329 : * schedule_hrtimeout_range - sleep until timeout
2330 : * @expires: timeout value (ktime_t)
2331 : * @delta: slack in expires timeout (ktime_t) for SCHED_OTHER tasks
2332 : * @mode: timer mode
2333 : *
2334 : * Make the current task sleep until the given expiry time has
2335 : * elapsed. The routine will return immediately unless
2336 : * the current task state has been set (see set_current_state()).
2337 : *
2338 : * The @delta argument gives the kernel the freedom to schedule the
2339 : * actual wakeup to a time that is both power and performance friendly
2340 : * for regular (non RT/DL) tasks.
2341 : * The kernel give the normal best effort behavior for "@expires+@delta",
2342 : * but may decide to fire the timer earlier, but no earlier than @expires.
2343 : *
2344 : * You can set the task state as follows -
2345 : *
2346 : * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
2347 : * pass before the routine returns unless the current task is explicitly
2348 : * woken up, (e.g. by wake_up_process()).
2349 : *
2350 : * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
2351 : * delivered to the current task or the current task is explicitly woken
2352 : * up.
2353 : *
2354 : * The current task state is guaranteed to be TASK_RUNNING when this
2355 : * routine returns.
2356 : *
2357 : * Returns 0 when the timer has expired. If the task was woken before the
2358 : * timer expired by a signal (only possible in state TASK_INTERRUPTIBLE) or
2359 : * by an explicit wakeup, it returns -EINTR.
2360 : */
2361 0 : int __sched schedule_hrtimeout_range(ktime_t *expires, u64 delta,
2362 : const enum hrtimer_mode mode)
2363 : {
2364 0 : return schedule_hrtimeout_range_clock(expires, delta, mode,
2365 : CLOCK_MONOTONIC);
2366 : }
2367 : EXPORT_SYMBOL_GPL(schedule_hrtimeout_range);
2368 :
2369 : /**
2370 : * schedule_hrtimeout - sleep until timeout
2371 : * @expires: timeout value (ktime_t)
2372 : * @mode: timer mode
2373 : *
2374 : * Make the current task sleep until the given expiry time has
2375 : * elapsed. The routine will return immediately unless
2376 : * the current task state has been set (see set_current_state()).
2377 : *
2378 : * You can set the task state as follows -
2379 : *
2380 : * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
2381 : * pass before the routine returns unless the current task is explicitly
2382 : * woken up, (e.g. by wake_up_process()).
2383 : *
2384 : * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
2385 : * delivered to the current task or the current task is explicitly woken
2386 : * up.
2387 : *
2388 : * The current task state is guaranteed to be TASK_RUNNING when this
2389 : * routine returns.
2390 : *
2391 : * Returns 0 when the timer has expired. If the task was woken before the
2392 : * timer expired by a signal (only possible in state TASK_INTERRUPTIBLE) or
2393 : * by an explicit wakeup, it returns -EINTR.
2394 : */
2395 0 : int __sched schedule_hrtimeout(ktime_t *expires,
2396 : const enum hrtimer_mode mode)
2397 : {
2398 0 : return schedule_hrtimeout_range(expires, 0, mode);
2399 : }
2400 : EXPORT_SYMBOL_GPL(schedule_hrtimeout);
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