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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Kernel internal timers
4 *
5 * Copyright (C) 1991, 1992 Linus Torvalds
6 *
7 * 1997-01-28 Modified by Finn Arne Gangstad to make timers scale better.
8 *
9 * 1997-09-10 Updated NTP code according to technical memorandum Jan '96
10 * "A Kernel Model for Precision Timekeeping" by Dave Mills
11 * 1998-12-24 Fixed a xtime SMP race (we need the xtime_lock rw spinlock to
12 * serialize accesses to xtime/lost_ticks).
13 * Copyright (C) 1998 Andrea Arcangeli
14 * 1999-03-10 Improved NTP compatibility by Ulrich Windl
15 * 2002-05-31 Move sys_sysinfo here and make its locking sane, Robert Love
16 * 2000-10-05 Implemented scalable SMP per-CPU timer handling.
17 * Copyright (C) 2000, 2001, 2002 Ingo Molnar
18 * Designed by David S. Miller, Alexey Kuznetsov and Ingo Molnar
19 */
20
21#include <linux/kernel_stat.h>
22#include <linux/export.h>
23#include <linux/interrupt.h>
24#include <linux/percpu.h>
25#include <linux/init.h>
26#include <linux/mm.h>
27#include <linux/swap.h>
28#include <linux/pid_namespace.h>
29#include <linux/notifier.h>
30#include <linux/thread_info.h>
31#include <linux/time.h>
32#include <linux/jiffies.h>
33#include <linux/posix-timers.h>
34#include <linux/cpu.h>
35#include <linux/syscalls.h>
36#include <linux/delay.h>
37#include <linux/tick.h>
38#include <linux/kallsyms.h>
39#include <linux/irq_work.h>
40#include <linux/sched/signal.h>
41#include <linux/sched/sysctl.h>
42#include <linux/sched/nohz.h>
43#include <linux/sched/debug.h>
44#include <linux/slab.h>
45#include <linux/compat.h>
46#include <linux/random.h>
47
48#include <linux/uaccess.h>
49#include <asm/unistd.h>
50#include <asm/div64.h>
51#include <asm/timex.h>
52#include <asm/io.h>
53
54#include "tick-internal.h"
55
56#define CREATE_TRACE_POINTS
57#include <trace/events/timer.h>
58
59__visible u64 jiffies_64 __cacheline_aligned_in_smp = INITIAL_JIFFIES;
60
61EXPORT_SYMBOL(jiffies_64);
62
63/*
64 * The timer wheel has LVL_DEPTH array levels. Each level provides an array of
65 * LVL_SIZE buckets. Each level is driven by its own clock and therefor each
66 * level has a different granularity.
67 *
68 * The level granularity is: LVL_CLK_DIV ^ lvl
69 * The level clock frequency is: HZ / (LVL_CLK_DIV ^ level)
70 *
71 * The array level of a newly armed timer depends on the relative expiry
72 * time. The farther the expiry time is away the higher the array level and
73 * therefor the granularity becomes.
74 *
75 * Contrary to the original timer wheel implementation, which aims for 'exact'
76 * expiry of the timers, this implementation removes the need for recascading
77 * the timers into the lower array levels. The previous 'classic' timer wheel
78 * implementation of the kernel already violated the 'exact' expiry by adding
79 * slack to the expiry time to provide batched expiration. The granularity
80 * levels provide implicit batching.
81 *
82 * This is an optimization of the original timer wheel implementation for the
83 * majority of the timer wheel use cases: timeouts. The vast majority of
84 * timeout timers (networking, disk I/O ...) are canceled before expiry. If
85 * the timeout expires it indicates that normal operation is disturbed, so it
86 * does not matter much whether the timeout comes with a slight delay.
87 *
88 * The only exception to this are networking timers with a small expiry
89 * time. They rely on the granularity. Those fit into the first wheel level,
90 * which has HZ granularity.
91 *
92 * We don't have cascading anymore. timers with a expiry time above the
93 * capacity of the last wheel level are force expired at the maximum timeout
94 * value of the last wheel level. From data sampling we know that the maximum
95 * value observed is 5 days (network connection tracking), so this should not
96 * be an issue.
97 *
98 * The currently chosen array constants values are a good compromise between
99 * array size and granularity.
100 *
101 * This results in the following granularity and range levels:
102 *
103 * HZ 1000 steps
104 * Level Offset Granularity Range
105 * 0 0 1 ms 0 ms - 63 ms
106 * 1 64 8 ms 64 ms - 511 ms
107 * 2 128 64 ms 512 ms - 4095 ms (512ms - ~4s)
108 * 3 192 512 ms 4096 ms - 32767 ms (~4s - ~32s)
109 * 4 256 4096 ms (~4s) 32768 ms - 262143 ms (~32s - ~4m)
110 * 5 320 32768 ms (~32s) 262144 ms - 2097151 ms (~4m - ~34m)
111 * 6 384 262144 ms (~4m) 2097152 ms - 16777215 ms (~34m - ~4h)
112 * 7 448 2097152 ms (~34m) 16777216 ms - 134217727 ms (~4h - ~1d)
113 * 8 512 16777216 ms (~4h) 134217728 ms - 1073741822 ms (~1d - ~12d)
114 *
115 * HZ 300
116 * Level Offset Granularity Range
117 * 0 0 3 ms 0 ms - 210 ms
118 * 1 64 26 ms 213 ms - 1703 ms (213ms - ~1s)
119 * 2 128 213 ms 1706 ms - 13650 ms (~1s - ~13s)
120 * 3 192 1706 ms (~1s) 13653 ms - 109223 ms (~13s - ~1m)
121 * 4 256 13653 ms (~13s) 109226 ms - 873810 ms (~1m - ~14m)
122 * 5 320 109226 ms (~1m) 873813 ms - 6990503 ms (~14m - ~1h)
123 * 6 384 873813 ms (~14m) 6990506 ms - 55924050 ms (~1h - ~15h)
124 * 7 448 6990506 ms (~1h) 55924053 ms - 447392423 ms (~15h - ~5d)
125 * 8 512 55924053 ms (~15h) 447392426 ms - 3579139406 ms (~5d - ~41d)
126 *
127 * HZ 250
128 * Level Offset Granularity Range
129 * 0 0 4 ms 0 ms - 255 ms
130 * 1 64 32 ms 256 ms - 2047 ms (256ms - ~2s)
131 * 2 128 256 ms 2048 ms - 16383 ms (~2s - ~16s)
132 * 3 192 2048 ms (~2s) 16384 ms - 131071 ms (~16s - ~2m)
133 * 4 256 16384 ms (~16s) 131072 ms - 1048575 ms (~2m - ~17m)
134 * 5 320 131072 ms (~2m) 1048576 ms - 8388607 ms (~17m - ~2h)
135 * 6 384 1048576 ms (~17m) 8388608 ms - 67108863 ms (~2h - ~18h)
136 * 7 448 8388608 ms (~2h) 67108864 ms - 536870911 ms (~18h - ~6d)
137 * 8 512 67108864 ms (~18h) 536870912 ms - 4294967288 ms (~6d - ~49d)
138 *
139 * HZ 100
140 * Level Offset Granularity Range
141 * 0 0 10 ms 0 ms - 630 ms
142 * 1 64 80 ms 640 ms - 5110 ms (640ms - ~5s)
143 * 2 128 640 ms 5120 ms - 40950 ms (~5s - ~40s)
144 * 3 192 5120 ms (~5s) 40960 ms - 327670 ms (~40s - ~5m)
145 * 4 256 40960 ms (~40s) 327680 ms - 2621430 ms (~5m - ~43m)
146 * 5 320 327680 ms (~5m) 2621440 ms - 20971510 ms (~43m - ~5h)
147 * 6 384 2621440 ms (~43m) 20971520 ms - 167772150 ms (~5h - ~1d)
148 * 7 448 20971520 ms (~5h) 167772160 ms - 1342177270 ms (~1d - ~15d)
149 */
150
151/* Clock divisor for the next level */
152#define LVL_CLK_SHIFT 3
153#define LVL_CLK_DIV (1UL << LVL_CLK_SHIFT)
154#define LVL_CLK_MASK (LVL_CLK_DIV - 1)
155#define LVL_SHIFT(n) ((n) * LVL_CLK_SHIFT)
156#define LVL_GRAN(n) (1UL << LVL_SHIFT(n))
157
158/*
159 * The time start value for each level to select the bucket at enqueue
160 * time.
161 */
162#define LVL_START(n) ((LVL_SIZE - 1) << (((n) - 1) * LVL_CLK_SHIFT))
163
164/* Size of each clock level */
165#define LVL_BITS 6
166#define LVL_SIZE (1UL << LVL_BITS)
167#define LVL_MASK (LVL_SIZE - 1)
168#define LVL_OFFS(n) ((n) * LVL_SIZE)
169
170/* Level depth */
171#if HZ > 100
172# define LVL_DEPTH 9
173# else
174# define LVL_DEPTH 8
175#endif
176
177/* The cutoff (max. capacity of the wheel) */
178#define WHEEL_TIMEOUT_CUTOFF (LVL_START(LVL_DEPTH))
179#define WHEEL_TIMEOUT_MAX (WHEEL_TIMEOUT_CUTOFF - LVL_GRAN(LVL_DEPTH - 1))
180
181/*
182 * The resulting wheel size. If NOHZ is configured we allocate two
183 * wheels so we have a separate storage for the deferrable timers.
184 */
185#define WHEEL_SIZE (LVL_SIZE * LVL_DEPTH)
186
187#ifdef CONFIG_NO_HZ_COMMON
188# define NR_BASES 2
189# define BASE_STD 0
190# define BASE_DEF 1
191#else
192# define NR_BASES 1
193# define BASE_STD 0
194# define BASE_DEF 0
195#endif
196
197struct timer_base {
198 raw_spinlock_t lock;
199 struct timer_list *running_timer;
200#ifdef CONFIG_PREEMPT_RT
201 spinlock_t expiry_lock;
202 atomic_t timer_waiters;
203#endif
204 unsigned long clk;
205 unsigned long next_expiry;
206 unsigned int cpu;
207 bool is_idle;
208 bool must_forward_clk;
209 DECLARE_BITMAP(pending_map, WHEEL_SIZE);
210 struct hlist_head vectors[WHEEL_SIZE];
211} ____cacheline_aligned;
212
213static DEFINE_PER_CPU(struct timer_base, timer_bases[NR_BASES]);
214
215#ifdef CONFIG_NO_HZ_COMMON
216
217static DEFINE_STATIC_KEY_FALSE(timers_nohz_active);
218static DEFINE_MUTEX(timer_keys_mutex);
219
220static void timer_update_keys(struct work_struct *work);
221static DECLARE_WORK(timer_update_work, timer_update_keys);
222
223#ifdef CONFIG_SMP
224unsigned int sysctl_timer_migration = 1;
225
226DEFINE_STATIC_KEY_FALSE(timers_migration_enabled);
227
228static void timers_update_migration(void)
229{
230 if (sysctl_timer_migration && tick_nohz_active)
231 static_branch_enable(&timers_migration_enabled);
232 else
233 static_branch_disable(&timers_migration_enabled);
234}
235#else
236static inline void timers_update_migration(void) { }
237#endif /* !CONFIG_SMP */
238
239static void timer_update_keys(struct work_struct *work)
240{
241 mutex_lock(&timer_keys_mutex);
242 timers_update_migration();
243 static_branch_enable(&timers_nohz_active);
244 mutex_unlock(&timer_keys_mutex);
245}
246
247void timers_update_nohz(void)
248{
249 schedule_work(&timer_update_work);
250}
251
252int timer_migration_handler(struct ctl_table *table, int write,
253 void *buffer, size_t *lenp, loff_t *ppos)
254{
255 int ret;
256
257 mutex_lock(&timer_keys_mutex);
258 ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
259 if (!ret && write)
260 timers_update_migration();
261 mutex_unlock(&timer_keys_mutex);
262 return ret;
263}
264
265static inline bool is_timers_nohz_active(void)
266{
267 return static_branch_unlikely(&timers_nohz_active);
268}
269#else
270static inline bool is_timers_nohz_active(void) { return false; }
271#endif /* NO_HZ_COMMON */
272
273static unsigned long round_jiffies_common(unsigned long j, int cpu,
274 bool force_up)
275{
276 int rem;
277 unsigned long original = j;
278
279 /*
280 * We don't want all cpus firing their timers at once hitting the
281 * same lock or cachelines, so we skew each extra cpu with an extra
282 * 3 jiffies. This 3 jiffies came originally from the mm/ code which
283 * already did this.
284 * The skew is done by adding 3*cpunr, then round, then subtract this
285 * extra offset again.
286 */
287 j += cpu * 3;
288
289 rem = j % HZ;
290
291 /*
292 * If the target jiffie is just after a whole second (which can happen
293 * due to delays of the timer irq, long irq off times etc etc) then
294 * we should round down to the whole second, not up. Use 1/4th second
295 * as cutoff for this rounding as an extreme upper bound for this.
296 * But never round down if @force_up is set.
297 */
298 if (rem < HZ/4 && !force_up) /* round down */
299 j = j - rem;
300 else /* round up */
301 j = j - rem + HZ;
302
303 /* now that we have rounded, subtract the extra skew again */
304 j -= cpu * 3;
305
306 /*
307 * Make sure j is still in the future. Otherwise return the
308 * unmodified value.
309 */
310 return time_is_after_jiffies(j) ? j : original;
311}
312
313/**
314 * __round_jiffies - function to round jiffies to a full second
315 * @j: the time in (absolute) jiffies that should be rounded
316 * @cpu: the processor number on which the timeout will happen
317 *
318 * __round_jiffies() rounds an absolute time in the future (in jiffies)
319 * up or down to (approximately) full seconds. This is useful for timers
320 * for which the exact time they fire does not matter too much, as long as
321 * they fire approximately every X seconds.
322 *
323 * By rounding these timers to whole seconds, all such timers will fire
324 * at the same time, rather than at various times spread out. The goal
325 * of this is to have the CPU wake up less, which saves power.
326 *
327 * The exact rounding is skewed for each processor to avoid all
328 * processors firing at the exact same time, which could lead
329 * to lock contention or spurious cache line bouncing.
330 *
331 * The return value is the rounded version of the @j parameter.
332 */
333unsigned long __round_jiffies(unsigned long j, int cpu)
334{
335 return round_jiffies_common(j, cpu, false);
336}
337EXPORT_SYMBOL_GPL(__round_jiffies);
338
339/**
340 * __round_jiffies_relative - function to round jiffies to a full second
341 * @j: the time in (relative) jiffies that should be rounded
342 * @cpu: the processor number on which the timeout will happen
343 *
344 * __round_jiffies_relative() rounds a time delta in the future (in jiffies)
345 * up or down to (approximately) full seconds. This is useful for timers
346 * for which the exact time they fire does not matter too much, as long as
347 * they fire approximately every X seconds.
348 *
349 * By rounding these timers to whole seconds, all such timers will fire
350 * at the same time, rather than at various times spread out. The goal
351 * of this is to have the CPU wake up less, which saves power.
352 *
353 * The exact rounding is skewed for each processor to avoid all
354 * processors firing at the exact same time, which could lead
355 * to lock contention or spurious cache line bouncing.
356 *
357 * The return value is the rounded version of the @j parameter.
358 */
359unsigned long __round_jiffies_relative(unsigned long j, int cpu)
360{
361 unsigned long j0 = jiffies;
362
363 /* Use j0 because jiffies might change while we run */
364 return round_jiffies_common(j + j0, cpu, false) - j0;
365}
366EXPORT_SYMBOL_GPL(__round_jiffies_relative);
367
368/**
369 * round_jiffies - function to round jiffies to a full second
370 * @j: the time in (absolute) jiffies that should be rounded
371 *
372 * round_jiffies() rounds an absolute time in the future (in jiffies)
373 * up or down to (approximately) full seconds. This is useful for timers
374 * for which the exact time they fire does not matter too much, as long as
375 * they fire approximately every X seconds.
376 *
377 * By rounding these timers to whole seconds, all such timers will fire
378 * at the same time, rather than at various times spread out. The goal
379 * of this is to have the CPU wake up less, which saves power.
380 *
381 * The return value is the rounded version of the @j parameter.
382 */
383unsigned long round_jiffies(unsigned long j)
384{
385 return round_jiffies_common(j, raw_smp_processor_id(), false);
386}
387EXPORT_SYMBOL_GPL(round_jiffies);
388
389/**
390 * round_jiffies_relative - function to round jiffies to a full second
391 * @j: the time in (relative) jiffies that should be rounded
392 *
393 * round_jiffies_relative() rounds a time delta in the future (in jiffies)
394 * up or down to (approximately) full seconds. This is useful for timers
395 * for which the exact time they fire does not matter too much, as long as
396 * they fire approximately every X seconds.
397 *
398 * By rounding these timers to whole seconds, all such timers will fire
399 * at the same time, rather than at various times spread out. The goal
400 * of this is to have the CPU wake up less, which saves power.
401 *
402 * The return value is the rounded version of the @j parameter.
403 */
404unsigned long round_jiffies_relative(unsigned long j)
405{
406 return __round_jiffies_relative(j, raw_smp_processor_id());
407}
408EXPORT_SYMBOL_GPL(round_jiffies_relative);
409
410/**
411 * __round_jiffies_up - function to round jiffies up to a full second
412 * @j: the time in (absolute) jiffies that should be rounded
413 * @cpu: the processor number on which the timeout will happen
414 *
415 * This is the same as __round_jiffies() except that it will never
416 * round down. This is useful for timeouts for which the exact time
417 * of firing does not matter too much, as long as they don't fire too
418 * early.
419 */
420unsigned long __round_jiffies_up(unsigned long j, int cpu)
421{
422 return round_jiffies_common(j, cpu, true);
423}
424EXPORT_SYMBOL_GPL(__round_jiffies_up);
425
426/**
427 * __round_jiffies_up_relative - function to round jiffies up to a full second
428 * @j: the time in (relative) jiffies that should be rounded
429 * @cpu: the processor number on which the timeout will happen
430 *
431 * This is the same as __round_jiffies_relative() except that it will never
432 * round down. This is useful for timeouts for which the exact time
433 * of firing does not matter too much, as long as they don't fire too
434 * early.
435 */
436unsigned long __round_jiffies_up_relative(unsigned long j, int cpu)
437{
438 unsigned long j0 = jiffies;
439
440 /* Use j0 because jiffies might change while we run */
441 return round_jiffies_common(j + j0, cpu, true) - j0;
442}
443EXPORT_SYMBOL_GPL(__round_jiffies_up_relative);
444
445/**
446 * round_jiffies_up - function to round jiffies up to a full second
447 * @j: the time in (absolute) jiffies that should be rounded
448 *
449 * This is the same as round_jiffies() except that it will never
450 * round down. This is useful for timeouts for which the exact time
451 * of firing does not matter too much, as long as they don't fire too
452 * early.
453 */
454unsigned long round_jiffies_up(unsigned long j)
455{
456 return round_jiffies_common(j, raw_smp_processor_id(), true);
457}
458EXPORT_SYMBOL_GPL(round_jiffies_up);
459
460/**
461 * round_jiffies_up_relative - function to round jiffies up to a full second
462 * @j: the time in (relative) jiffies that should be rounded
463 *
464 * This is the same as round_jiffies_relative() except that it will never
465 * round down. This is useful for timeouts for which the exact time
466 * of firing does not matter too much, as long as they don't fire too
467 * early.
468 */
469unsigned long round_jiffies_up_relative(unsigned long j)
470{
471 return __round_jiffies_up_relative(j, raw_smp_processor_id());
472}
473EXPORT_SYMBOL_GPL(round_jiffies_up_relative);
474
475
476static inline unsigned int timer_get_idx(struct timer_list *timer)
477{
478 return (timer->flags & TIMER_ARRAYMASK) >> TIMER_ARRAYSHIFT;
479}
480
481static inline void timer_set_idx(struct timer_list *timer, unsigned int idx)
482{
483 timer->flags = (timer->flags & ~TIMER_ARRAYMASK) |
484 idx << TIMER_ARRAYSHIFT;
485}
486
487/*
488 * Helper function to calculate the array index for a given expiry
489 * time.
490 */
491static inline unsigned calc_index(unsigned expires, unsigned lvl)
492{
493 expires = (expires + LVL_GRAN(lvl)) >> LVL_SHIFT(lvl);
494 return LVL_OFFS(lvl) + (expires & LVL_MASK);
495}
496
497static int calc_wheel_index(unsigned long expires, unsigned long clk)
498{
499 unsigned long delta = expires - clk;
500 unsigned int idx;
501
502 if (delta < LVL_START(1)) {
503 idx = calc_index(expires, 0);
504 } else if (delta < LVL_START(2)) {
505 idx = calc_index(expires, 1);
506 } else if (delta < LVL_START(3)) {
507 idx = calc_index(expires, 2);
508 } else if (delta < LVL_START(4)) {
509 idx = calc_index(expires, 3);
510 } else if (delta < LVL_START(5)) {
511 idx = calc_index(expires, 4);
512 } else if (delta < LVL_START(6)) {
513 idx = calc_index(expires, 5);
514 } else if (delta < LVL_START(7)) {
515 idx = calc_index(expires, 6);
516 } else if (LVL_DEPTH > 8 && delta < LVL_START(8)) {
517 idx = calc_index(expires, 7);
518 } else if ((long) delta < 0) {
519 idx = clk & LVL_MASK;
520 } else {
521 /*
522 * Force expire obscene large timeouts to expire at the
523 * capacity limit of the wheel.
524 */
525 if (delta >= WHEEL_TIMEOUT_CUTOFF)
526 expires = clk + WHEEL_TIMEOUT_MAX;
527
528 idx = calc_index(expires, LVL_DEPTH - 1);
529 }
530 return idx;
531}
532
533/*
534 * Enqueue the timer into the hash bucket, mark it pending in
535 * the bitmap and store the index in the timer flags.
536 */
537static void enqueue_timer(struct timer_base *base, struct timer_list *timer,
538 unsigned int idx)
539{
540 hlist_add_head(&timer->entry, base->vectors + idx);
541 __set_bit(idx, base->pending_map);
542 timer_set_idx(timer, idx);
543
544 trace_timer_start(timer, timer->expires, timer->flags);
545}
546
547static void
548__internal_add_timer(struct timer_base *base, struct timer_list *timer)
549{
550 unsigned int idx;
551
552 idx = calc_wheel_index(timer->expires, base->clk);
553 enqueue_timer(base, timer, idx);
554}
555
556static void
557trigger_dyntick_cpu(struct timer_base *base, struct timer_list *timer)
558{
559 if (!is_timers_nohz_active())
560 return;
561
562 /*
563 * TODO: This wants some optimizing similar to the code below, but we
564 * will do that when we switch from push to pull for deferrable timers.
565 */
566 if (timer->flags & TIMER_DEFERRABLE) {
567 if (tick_nohz_full_cpu(base->cpu))
568 wake_up_nohz_cpu(base->cpu);
569 return;
570 }
571
572 /*
573 * We might have to IPI the remote CPU if the base is idle and the
574 * timer is not deferrable. If the other CPU is on the way to idle
575 * then it can't set base->is_idle as we hold the base lock:
576 */
577 if (!base->is_idle)
578 return;
579
580 /* Check whether this is the new first expiring timer: */
581 if (time_after_eq(timer->expires, base->next_expiry))
582 return;
583
584 /*
585 * Set the next expiry time and kick the CPU so it can reevaluate the
586 * wheel:
587 */
588 if (time_before(timer->expires, base->clk)) {
589 /*
590 * Prevent from forward_timer_base() moving the base->clk
591 * backward
592 */
593 base->next_expiry = base->clk;
594 } else {
595 base->next_expiry = timer->expires;
596 }
597 wake_up_nohz_cpu(base->cpu);
598}
599
600static void
601internal_add_timer(struct timer_base *base, struct timer_list *timer)
602{
603 __internal_add_timer(base, timer);
604 trigger_dyntick_cpu(base, timer);
605}
606
607#ifdef CONFIG_DEBUG_OBJECTS_TIMERS
608
609static struct debug_obj_descr timer_debug_descr;
610
611static void *timer_debug_hint(void *addr)
612{
613 return ((struct timer_list *) addr)->function;
614}
615
616static bool timer_is_static_object(void *addr)
617{
618 struct timer_list *timer = addr;
619
620 return (timer->entry.pprev == NULL &&
621 timer->entry.next == TIMER_ENTRY_STATIC);
622}
623
624/*
625 * fixup_init is called when:
626 * - an active object is initialized
627 */
628static bool timer_fixup_init(void *addr, enum debug_obj_state state)
629{
630 struct timer_list *timer = addr;
631
632 switch (state) {
633 case ODEBUG_STATE_ACTIVE:
634 del_timer_sync(timer);
635 debug_object_init(timer, &timer_debug_descr);
636 return true;
637 default:
638 return false;
639 }
640}
641
642/* Stub timer callback for improperly used timers. */
643static void stub_timer(struct timer_list *unused)
644{
645 WARN_ON(1);
646}
647
648/*
649 * fixup_activate is called when:
650 * - an active object is activated
651 * - an unknown non-static object is activated
652 */
653static bool timer_fixup_activate(void *addr, enum debug_obj_state state)
654{
655 struct timer_list *timer = addr;
656
657 switch (state) {
658 case ODEBUG_STATE_NOTAVAILABLE:
659 timer_setup(timer, stub_timer, 0);
660 return true;
661
662 case ODEBUG_STATE_ACTIVE:
663 WARN_ON(1);
664 /* fall through */
665 default:
666 return false;
667 }
668}
669
670/*
671 * fixup_free is called when:
672 * - an active object is freed
673 */
674static bool timer_fixup_free(void *addr, enum debug_obj_state state)
675{
676 struct timer_list *timer = addr;
677
678 switch (state) {
679 case ODEBUG_STATE_ACTIVE:
680 del_timer_sync(timer);
681 debug_object_free(timer, &timer_debug_descr);
682 return true;
683 default:
684 return false;
685 }
686}
687
688/*
689 * fixup_assert_init is called when:
690 * - an untracked/uninit-ed object is found
691 */
692static bool timer_fixup_assert_init(void *addr, enum debug_obj_state state)
693{
694 struct timer_list *timer = addr;
695
696 switch (state) {
697 case ODEBUG_STATE_NOTAVAILABLE:
698 timer_setup(timer, stub_timer, 0);
699 return true;
700 default:
701 return false;
702 }
703}
704
705static struct debug_obj_descr timer_debug_descr = {
706 .name = "timer_list",
707 .debug_hint = timer_debug_hint,
708 .is_static_object = timer_is_static_object,
709 .fixup_init = timer_fixup_init,
710 .fixup_activate = timer_fixup_activate,
711 .fixup_free = timer_fixup_free,
712 .fixup_assert_init = timer_fixup_assert_init,
713};
714
715static inline void debug_timer_init(struct timer_list *timer)
716{
717 debug_object_init(timer, &timer_debug_descr);
718}
719
720static inline void debug_timer_activate(struct timer_list *timer)
721{
722 debug_object_activate(timer, &timer_debug_descr);
723}
724
725static inline void debug_timer_deactivate(struct timer_list *timer)
726{
727 debug_object_deactivate(timer, &timer_debug_descr);
728}
729
730static inline void debug_timer_free(struct timer_list *timer)
731{
732 debug_object_free(timer, &timer_debug_descr);
733}
734
735static inline void debug_timer_assert_init(struct timer_list *timer)
736{
737 debug_object_assert_init(timer, &timer_debug_descr);
738}
739
740static void do_init_timer(struct timer_list *timer,
741 void (*func)(struct timer_list *),
742 unsigned int flags,
743 const char *name, struct lock_class_key *key);
744
745void init_timer_on_stack_key(struct timer_list *timer,
746 void (*func)(struct timer_list *),
747 unsigned int flags,
748 const char *name, struct lock_class_key *key)
749{
750 debug_object_init_on_stack(timer, &timer_debug_descr);
751 do_init_timer(timer, func, flags, name, key);
752}
753EXPORT_SYMBOL_GPL(init_timer_on_stack_key);
754
755void destroy_timer_on_stack(struct timer_list *timer)
756{
757 debug_object_free(timer, &timer_debug_descr);
758}
759EXPORT_SYMBOL_GPL(destroy_timer_on_stack);
760
761#else
762static inline void debug_timer_init(struct timer_list *timer) { }
763static inline void debug_timer_activate(struct timer_list *timer) { }
764static inline void debug_timer_deactivate(struct timer_list *timer) { }
765static inline void debug_timer_assert_init(struct timer_list *timer) { }
766#endif
767
768static inline void debug_init(struct timer_list *timer)
769{
770 debug_timer_init(timer);
771 trace_timer_init(timer);
772}
773
774static inline void debug_deactivate(struct timer_list *timer)
775{
776 debug_timer_deactivate(timer);
777 trace_timer_cancel(timer);
778}
779
780static inline void debug_assert_init(struct timer_list *timer)
781{
782 debug_timer_assert_init(timer);
783}
784
785static void do_init_timer(struct timer_list *timer,
786 void (*func)(struct timer_list *),
787 unsigned int flags,
788 const char *name, struct lock_class_key *key)
789{
790 timer->entry.pprev = NULL;
791 timer->function = func;
792 timer->flags = flags | raw_smp_processor_id();
793 lockdep_init_map(&timer->lockdep_map, name, key, 0);
794}
795
796/**
797 * init_timer_key - initialize a timer
798 * @timer: the timer to be initialized
799 * @func: timer callback function
800 * @flags: timer flags
801 * @name: name of the timer
802 * @key: lockdep class key of the fake lock used for tracking timer
803 * sync lock dependencies
804 *
805 * init_timer_key() must be done to a timer prior calling *any* of the
806 * other timer functions.
807 */
808void init_timer_key(struct timer_list *timer,
809 void (*func)(struct timer_list *), unsigned int flags,
810 const char *name, struct lock_class_key *key)
811{
812 debug_init(timer);
813 do_init_timer(timer, func, flags, name, key);
814}
815EXPORT_SYMBOL(init_timer_key);
816
817static inline void detach_timer(struct timer_list *timer, bool clear_pending)
818{
819 struct hlist_node *entry = &timer->entry;
820
821 debug_deactivate(timer);
822
823 __hlist_del(entry);
824 if (clear_pending)
825 entry->pprev = NULL;
826 entry->next = LIST_POISON2;
827}
828
829static int detach_if_pending(struct timer_list *timer, struct timer_base *base,
830 bool clear_pending)
831{
832 unsigned idx = timer_get_idx(timer);
833
834 if (!timer_pending(timer))
835 return 0;
836
837 if (hlist_is_singular_node(&timer->entry, base->vectors + idx))
838 __clear_bit(idx, base->pending_map);
839
840 detach_timer(timer, clear_pending);
841 return 1;
842}
843
844static inline struct timer_base *get_timer_cpu_base(u32 tflags, u32 cpu)
845{
846 struct timer_base *base = per_cpu_ptr(&timer_bases[BASE_STD], cpu);
847
848 /*
849 * If the timer is deferrable and NO_HZ_COMMON is set then we need
850 * to use the deferrable base.
851 */
852 if (IS_ENABLED(CONFIG_NO_HZ_COMMON) && (tflags & TIMER_DEFERRABLE))
853 base = per_cpu_ptr(&timer_bases[BASE_DEF], cpu);
854 return base;
855}
856
857static inline struct timer_base *get_timer_this_cpu_base(u32 tflags)
858{
859 struct timer_base *base = this_cpu_ptr(&timer_bases[BASE_STD]);
860
861 /*
862 * If the timer is deferrable and NO_HZ_COMMON is set then we need
863 * to use the deferrable base.
864 */
865 if (IS_ENABLED(CONFIG_NO_HZ_COMMON) && (tflags & TIMER_DEFERRABLE))
866 base = this_cpu_ptr(&timer_bases[BASE_DEF]);
867 return base;
868}
869
870static inline struct timer_base *get_timer_base(u32 tflags)
871{
872 return get_timer_cpu_base(tflags, tflags & TIMER_CPUMASK);
873}
874
875static inline struct timer_base *
876get_target_base(struct timer_base *base, unsigned tflags)
877{
878#if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ_COMMON)
879 if (static_branch_likely(&timers_migration_enabled) &&
880 !(tflags & TIMER_PINNED))
881 return get_timer_cpu_base(tflags, get_nohz_timer_target());
882#endif
883 return get_timer_this_cpu_base(tflags);
884}
885
886static inline void forward_timer_base(struct timer_base *base)
887{
888#ifdef CONFIG_NO_HZ_COMMON
889 unsigned long jnow;
890
891 /*
892 * We only forward the base when we are idle or have just come out of
893 * idle (must_forward_clk logic), and have a delta between base clock
894 * and jiffies. In the common case, run_timers will take care of it.
895 */
896 if (likely(!base->must_forward_clk))
897 return;
898
899 jnow = READ_ONCE(jiffies);
900 base->must_forward_clk = base->is_idle;
901 if ((long)(jnow - base->clk) < 2)
902 return;
903
904 /*
905 * If the next expiry value is > jiffies, then we fast forward to
906 * jiffies otherwise we forward to the next expiry value.
907 */
908 if (time_after(base->next_expiry, jnow)) {
909 base->clk = jnow;
910 } else {
911 if (WARN_ON_ONCE(time_before(base->next_expiry, base->clk)))
912 return;
913 base->clk = base->next_expiry;
914 }
915#endif
916}
917
918
919/*
920 * We are using hashed locking: Holding per_cpu(timer_bases[x]).lock means
921 * that all timers which are tied to this base are locked, and the base itself
922 * is locked too.
923 *
924 * So __run_timers/migrate_timers can safely modify all timers which could
925 * be found in the base->vectors array.
926 *
927 * When a timer is migrating then the TIMER_MIGRATING flag is set and we need
928 * to wait until the migration is done.
929 */
930static struct timer_base *lock_timer_base(struct timer_list *timer,
931 unsigned long *flags)
932 __acquires(timer->base->lock)
933{
934 for (;;) {
935 struct timer_base *base;
936 u32 tf;
937
938 /*
939 * We need to use READ_ONCE() here, otherwise the compiler
940 * might re-read @tf between the check for TIMER_MIGRATING
941 * and spin_lock().
942 */
943 tf = READ_ONCE(timer->flags);
944
945 if (!(tf & TIMER_MIGRATING)) {
946 base = get_timer_base(tf);
947 raw_spin_lock_irqsave(&base->lock, *flags);
948 if (timer->flags == tf)
949 return base;
950 raw_spin_unlock_irqrestore(&base->lock, *flags);
951 }
952 cpu_relax();
953 }
954}
955
956#define MOD_TIMER_PENDING_ONLY 0x01
957#define MOD_TIMER_REDUCE 0x02
958#define MOD_TIMER_NOTPENDING 0x04
959
960static inline int
961__mod_timer(struct timer_list *timer, unsigned long expires, unsigned int options)
962{
963 struct timer_base *base, *new_base;
964 unsigned int idx = UINT_MAX;
965 unsigned long clk = 0, flags;
966 int ret = 0;
967
968 BUG_ON(!timer->function);
969
970 /*
971 * This is a common optimization triggered by the networking code - if
972 * the timer is re-modified to have the same timeout or ends up in the
973 * same array bucket then just return:
974 */
975 if (!(options & MOD_TIMER_NOTPENDING) && timer_pending(timer)) {
976 /*
977 * The downside of this optimization is that it can result in
978 * larger granularity than you would get from adding a new
979 * timer with this expiry.
980 */
981 long diff = timer->expires - expires;
982
983 if (!diff)
984 return 1;
985 if (options & MOD_TIMER_REDUCE && diff <= 0)
986 return 1;
987
988 /*
989 * We lock timer base and calculate the bucket index right
990 * here. If the timer ends up in the same bucket, then we
991 * just update the expiry time and avoid the whole
992 * dequeue/enqueue dance.
993 */
994 base = lock_timer_base(timer, &flags);
995 forward_timer_base(base);
996
997 if (timer_pending(timer) && (options & MOD_TIMER_REDUCE) &&
998 time_before_eq(timer->expires, expires)) {
999 ret = 1;
1000 goto out_unlock;
1001 }
1002
1003 clk = base->clk;
1004 idx = calc_wheel_index(expires, clk);
1005
1006 /*
1007 * Retrieve and compare the array index of the pending
1008 * timer. If it matches set the expiry to the new value so a
1009 * subsequent call will exit in the expires check above.
1010 */
1011 if (idx == timer_get_idx(timer)) {
1012 if (!(options & MOD_TIMER_REDUCE))
1013 timer->expires = expires;
1014 else if (time_after(timer->expires, expires))
1015 timer->expires = expires;
1016 ret = 1;
1017 goto out_unlock;
1018 }
1019 } else {
1020 base = lock_timer_base(timer, &flags);
1021 forward_timer_base(base);
1022 }
1023
1024 ret = detach_if_pending(timer, base, false);
1025 if (!ret && (options & MOD_TIMER_PENDING_ONLY))
1026 goto out_unlock;
1027
1028 new_base = get_target_base(base, timer->flags);
1029
1030 if (base != new_base) {
1031 /*
1032 * We are trying to schedule the timer on the new base.
1033 * However we can't change timer's base while it is running,
1034 * otherwise del_timer_sync() can't detect that the timer's
1035 * handler yet has not finished. This also guarantees that the
1036 * timer is serialized wrt itself.
1037 */
1038 if (likely(base->running_timer != timer)) {
1039 /* See the comment in lock_timer_base() */
1040 timer->flags |= TIMER_MIGRATING;
1041
1042 raw_spin_unlock(&base->lock);
1043 base = new_base;
1044 raw_spin_lock(&base->lock);
1045 WRITE_ONCE(timer->flags,
1046 (timer->flags & ~TIMER_BASEMASK) | base->cpu);
1047 forward_timer_base(base);
1048 }
1049 }
1050
1051 debug_timer_activate(timer);
1052
1053 timer->expires = expires;
1054 /*
1055 * If 'idx' was calculated above and the base time did not advance
1056 * between calculating 'idx' and possibly switching the base, only
1057 * enqueue_timer() and trigger_dyntick_cpu() is required. Otherwise
1058 * we need to (re)calculate the wheel index via
1059 * internal_add_timer().
1060 */
1061 if (idx != UINT_MAX && clk == base->clk) {
1062 enqueue_timer(base, timer, idx);
1063 trigger_dyntick_cpu(base, timer);
1064 } else {
1065 internal_add_timer(base, timer);
1066 }
1067
1068out_unlock:
1069 raw_spin_unlock_irqrestore(&base->lock, flags);
1070
1071 return ret;
1072}
1073
1074/**
1075 * mod_timer_pending - modify a pending timer's timeout
1076 * @timer: the pending timer to be modified
1077 * @expires: new timeout in jiffies
1078 *
1079 * mod_timer_pending() is the same for pending timers as mod_timer(),
1080 * but will not re-activate and modify already deleted timers.
1081 *
1082 * It is useful for unserialized use of timers.
1083 */
1084int mod_timer_pending(struct timer_list *timer, unsigned long expires)
1085{
1086 return __mod_timer(timer, expires, MOD_TIMER_PENDING_ONLY);
1087}
1088EXPORT_SYMBOL(mod_timer_pending);
1089
1090/**
1091 * mod_timer - modify a timer's timeout
1092 * @timer: the timer to be modified
1093 * @expires: new timeout in jiffies
1094 *
1095 * mod_timer() is a more efficient way to update the expire field of an
1096 * active timer (if the timer is inactive it will be activated)
1097 *
1098 * mod_timer(timer, expires) is equivalent to:
1099 *
1100 * del_timer(timer); timer->expires = expires; add_timer(timer);
1101 *
1102 * Note that if there are multiple unserialized concurrent users of the
1103 * same timer, then mod_timer() is the only safe way to modify the timeout,
1104 * since add_timer() cannot modify an already running timer.
1105 *
1106 * The function returns whether it has modified a pending timer or not.
1107 * (ie. mod_timer() of an inactive timer returns 0, mod_timer() of an
1108 * active timer returns 1.)
1109 */
1110int mod_timer(struct timer_list *timer, unsigned long expires)
1111{
1112 return __mod_timer(timer, expires, 0);
1113}
1114EXPORT_SYMBOL(mod_timer);
1115
1116/**
1117 * timer_reduce - Modify a timer's timeout if it would reduce the timeout
1118 * @timer: The timer to be modified
1119 * @expires: New timeout in jiffies
1120 *
1121 * timer_reduce() is very similar to mod_timer(), except that it will only
1122 * modify a running timer if that would reduce the expiration time (it will
1123 * start a timer that isn't running).
1124 */
1125int timer_reduce(struct timer_list *timer, unsigned long expires)
1126{
1127 return __mod_timer(timer, expires, MOD_TIMER_REDUCE);
1128}
1129EXPORT_SYMBOL(timer_reduce);
1130
1131/**
1132 * add_timer - start a timer
1133 * @timer: the timer to be added
1134 *
1135 * The kernel will do a ->function(@timer) callback from the
1136 * timer interrupt at the ->expires point in the future. The
1137 * current time is 'jiffies'.
1138 *
1139 * The timer's ->expires, ->function fields must be set prior calling this
1140 * function.
1141 *
1142 * Timers with an ->expires field in the past will be executed in the next
1143 * timer tick.
1144 */
1145void add_timer(struct timer_list *timer)
1146{
1147 BUG_ON(timer_pending(timer));
1148 __mod_timer(timer, timer->expires, MOD_TIMER_NOTPENDING);
1149}
1150EXPORT_SYMBOL(add_timer);
1151
1152/**
1153 * add_timer_on - start a timer on a particular CPU
1154 * @timer: the timer to be added
1155 * @cpu: the CPU to start it on
1156 *
1157 * This is not very scalable on SMP. Double adds are not possible.
1158 */
1159void add_timer_on(struct timer_list *timer, int cpu)
1160{
1161 struct timer_base *new_base, *base;
1162 unsigned long flags;
1163
1164 BUG_ON(timer_pending(timer) || !timer->function);
1165
1166 new_base = get_timer_cpu_base(timer->flags, cpu);
1167
1168 /*
1169 * If @timer was on a different CPU, it should be migrated with the
1170 * old base locked to prevent other operations proceeding with the
1171 * wrong base locked. See lock_timer_base().
1172 */
1173 base = lock_timer_base(timer, &flags);
1174 if (base != new_base) {
1175 timer->flags |= TIMER_MIGRATING;
1176
1177 raw_spin_unlock(&base->lock);
1178 base = new_base;
1179 raw_spin_lock(&base->lock);
1180 WRITE_ONCE(timer->flags,
1181 (timer->flags & ~TIMER_BASEMASK) | cpu);
1182 }
1183 forward_timer_base(base);
1184
1185 debug_timer_activate(timer);
1186 internal_add_timer(base, timer);
1187 raw_spin_unlock_irqrestore(&base->lock, flags);
1188}
1189EXPORT_SYMBOL_GPL(add_timer_on);
1190
1191/**
1192 * del_timer - deactivate a timer.
1193 * @timer: the timer to be deactivated
1194 *
1195 * del_timer() deactivates a timer - this works on both active and inactive
1196 * timers.
1197 *
1198 * The function returns whether it has deactivated a pending timer or not.
1199 * (ie. del_timer() of an inactive timer returns 0, del_timer() of an
1200 * active timer returns 1.)
1201 */
1202int del_timer(struct timer_list *timer)
1203{
1204 struct timer_base *base;
1205 unsigned long flags;
1206 int ret = 0;
1207
1208 debug_assert_init(timer);
1209
1210 if (timer_pending(timer)) {
1211 base = lock_timer_base(timer, &flags);
1212 ret = detach_if_pending(timer, base, true);
1213 raw_spin_unlock_irqrestore(&base->lock, flags);
1214 }
1215
1216 return ret;
1217}
1218EXPORT_SYMBOL(del_timer);
1219
1220/**
1221 * try_to_del_timer_sync - Try to deactivate a timer
1222 * @timer: timer to delete
1223 *
1224 * This function tries to deactivate a timer. Upon successful (ret >= 0)
1225 * exit the timer is not queued and the handler is not running on any CPU.
1226 */
1227int try_to_del_timer_sync(struct timer_list *timer)
1228{
1229 struct timer_base *base;
1230 unsigned long flags;
1231 int ret = -1;
1232
1233 debug_assert_init(timer);
1234
1235 base = lock_timer_base(timer, &flags);
1236
1237 if (base->running_timer != timer)
1238 ret = detach_if_pending(timer, base, true);
1239
1240 raw_spin_unlock_irqrestore(&base->lock, flags);
1241
1242 return ret;
1243}
1244EXPORT_SYMBOL(try_to_del_timer_sync);
1245
1246#ifdef CONFIG_PREEMPT_RT
1247static __init void timer_base_init_expiry_lock(struct timer_base *base)
1248{
1249 spin_lock_init(&base->expiry_lock);
1250}
1251
1252static inline void timer_base_lock_expiry(struct timer_base *base)
1253{
1254 spin_lock(&base->expiry_lock);
1255}
1256
1257static inline void timer_base_unlock_expiry(struct timer_base *base)
1258{
1259 spin_unlock(&base->expiry_lock);
1260}
1261
1262/*
1263 * The counterpart to del_timer_wait_running().
1264 *
1265 * If there is a waiter for base->expiry_lock, then it was waiting for the
1266 * timer callback to finish. Drop expiry_lock and reaquire it. That allows
1267 * the waiter to acquire the lock and make progress.
1268 */
1269static void timer_sync_wait_running(struct timer_base *base)
1270{
1271 if (atomic_read(&base->timer_waiters)) {
1272 spin_unlock(&base->expiry_lock);
1273 spin_lock(&base->expiry_lock);
1274 }
1275}
1276
1277/*
1278 * This function is called on PREEMPT_RT kernels when the fast path
1279 * deletion of a timer failed because the timer callback function was
1280 * running.
1281 *
1282 * This prevents priority inversion, if the softirq thread on a remote CPU
1283 * got preempted, and it prevents a life lock when the task which tries to
1284 * delete a timer preempted the softirq thread running the timer callback
1285 * function.
1286 */
1287static void del_timer_wait_running(struct timer_list *timer)
1288{
1289 u32 tf;
1290
1291 tf = READ_ONCE(timer->flags);
1292 if (!(tf & TIMER_MIGRATING)) {
1293 struct timer_base *base = get_timer_base(tf);
1294
1295 /*
1296 * Mark the base as contended and grab the expiry lock,
1297 * which is held by the softirq across the timer
1298 * callback. Drop the lock immediately so the softirq can
1299 * expire the next timer. In theory the timer could already
1300 * be running again, but that's more than unlikely and just
1301 * causes another wait loop.
1302 */
1303 atomic_inc(&base->timer_waiters);
1304 spin_lock_bh(&base->expiry_lock);
1305 atomic_dec(&base->timer_waiters);
1306 spin_unlock_bh(&base->expiry_lock);
1307 }
1308}
1309#else
1310static inline void timer_base_init_expiry_lock(struct timer_base *base) { }
1311static inline void timer_base_lock_expiry(struct timer_base *base) { }
1312static inline void timer_base_unlock_expiry(struct timer_base *base) { }
1313static inline void timer_sync_wait_running(struct timer_base *base) { }
1314static inline void del_timer_wait_running(struct timer_list *timer) { }
1315#endif
1316
1317#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RT)
1318/**
1319 * del_timer_sync - deactivate a timer and wait for the handler to finish.
1320 * @timer: the timer to be deactivated
1321 *
1322 * This function only differs from del_timer() on SMP: besides deactivating
1323 * the timer it also makes sure the handler has finished executing on other
1324 * CPUs.
1325 *
1326 * Synchronization rules: Callers must prevent restarting of the timer,
1327 * otherwise this function is meaningless. It must not be called from
1328 * interrupt contexts unless the timer is an irqsafe one. The caller must
1329 * not hold locks which would prevent completion of the timer's
1330 * handler. The timer's handler must not call add_timer_on(). Upon exit the
1331 * timer is not queued and the handler is not running on any CPU.
1332 *
1333 * Note: For !irqsafe timers, you must not hold locks that are held in
1334 * interrupt context while calling this function. Even if the lock has
1335 * nothing to do with the timer in question. Here's why::
1336 *
1337 * CPU0 CPU1
1338 * ---- ----
1339 * <SOFTIRQ>
1340 * call_timer_fn();
1341 * base->running_timer = mytimer;
1342 * spin_lock_irq(somelock);
1343 * <IRQ>
1344 * spin_lock(somelock);
1345 * del_timer_sync(mytimer);
1346 * while (base->running_timer == mytimer);
1347 *
1348 * Now del_timer_sync() will never return and never release somelock.
1349 * The interrupt on the other CPU is waiting to grab somelock but
1350 * it has interrupted the softirq that CPU0 is waiting to finish.
1351 *
1352 * The function returns whether it has deactivated a pending timer or not.
1353 */
1354int del_timer_sync(struct timer_list *timer)
1355{
1356 int ret;
1357
1358#ifdef CONFIG_LOCKDEP
1359 unsigned long flags;
1360
1361 /*
1362 * If lockdep gives a backtrace here, please reference
1363 * the synchronization rules above.
1364 */
1365 local_irq_save(flags);
1366 lock_map_acquire(&timer->lockdep_map);
1367 lock_map_release(&timer->lockdep_map);
1368 local_irq_restore(flags);
1369#endif
1370 /*
1371 * don't use it in hardirq context, because it
1372 * could lead to deadlock.
1373 */
1374 WARN_ON(in_irq() && !(timer->flags & TIMER_IRQSAFE));
1375
1376 do {
1377 ret = try_to_del_timer_sync(timer);
1378
1379 if (unlikely(ret < 0)) {
1380 del_timer_wait_running(timer);
1381 cpu_relax();
1382 }
1383 } while (ret < 0);
1384
1385 return ret;
1386}
1387EXPORT_SYMBOL(del_timer_sync);
1388#endif
1389
1390static void call_timer_fn(struct timer_list *timer,
1391 void (*fn)(struct timer_list *),
1392 unsigned long baseclk)
1393{
1394 int count = preempt_count();
1395
1396#ifdef CONFIG_LOCKDEP
1397 /*
1398 * It is permissible to free the timer from inside the
1399 * function that is called from it, this we need to take into
1400 * account for lockdep too. To avoid bogus "held lock freed"
1401 * warnings as well as problems when looking into
1402 * timer->lockdep_map, make a copy and use that here.
1403 */
1404 struct lockdep_map lockdep_map;
1405
1406 lockdep_copy_map(&lockdep_map, &timer->lockdep_map);
1407#endif
1408 /*
1409 * Couple the lock chain with the lock chain at
1410 * del_timer_sync() by acquiring the lock_map around the fn()
1411 * call here and in del_timer_sync().
1412 */
1413 lock_map_acquire(&lockdep_map);
1414
1415 trace_timer_expire_entry(timer, baseclk);
1416 fn(timer);
1417 trace_timer_expire_exit(timer);
1418
1419 lock_map_release(&lockdep_map);
1420
1421 if (count != preempt_count()) {
1422 WARN_ONCE(1, "timer: %pS preempt leak: %08x -> %08x\n",
1423 fn, count, preempt_count());
1424 /*
1425 * Restore the preempt count. That gives us a decent
1426 * chance to survive and extract information. If the
1427 * callback kept a lock held, bad luck, but not worse
1428 * than the BUG() we had.
1429 */
1430 preempt_count_set(count);
1431 }
1432}
1433
1434static void expire_timers(struct timer_base *base, struct hlist_head *head)
1435{
1436 /*
1437 * This value is required only for tracing. base->clk was
1438 * incremented directly before expire_timers was called. But expiry
1439 * is related to the old base->clk value.
1440 */
1441 unsigned long baseclk = base->clk - 1;
1442
1443 while (!hlist_empty(head)) {
1444 struct timer_list *timer;
1445 void (*fn)(struct timer_list *);
1446
1447 timer = hlist_entry(head->first, struct timer_list, entry);
1448
1449 base->running_timer = timer;
1450 detach_timer(timer, true);
1451
1452 fn = timer->function;
1453
1454 if (timer->flags & TIMER_IRQSAFE) {
1455 raw_spin_unlock(&base->lock);
1456 call_timer_fn(timer, fn, baseclk);
1457 base->running_timer = NULL;
1458 raw_spin_lock(&base->lock);
1459 } else {
1460 raw_spin_unlock_irq(&base->lock);
1461 call_timer_fn(timer, fn, baseclk);
1462 base->running_timer = NULL;
1463 timer_sync_wait_running(base);
1464 raw_spin_lock_irq(&base->lock);
1465 }
1466 }
1467}
1468
1469static int __collect_expired_timers(struct timer_base *base,
1470 struct hlist_head *heads)
1471{
1472 unsigned long clk = base->clk;
1473 struct hlist_head *vec;
1474 int i, levels = 0;
1475 unsigned int idx;
1476
1477 for (i = 0; i < LVL_DEPTH; i++) {
1478 idx = (clk & LVL_MASK) + i * LVL_SIZE;
1479
1480 if (__test_and_clear_bit(idx, base->pending_map)) {
1481 vec = base->vectors + idx;
1482 hlist_move_list(vec, heads++);
1483 levels++;
1484 }
1485 /* Is it time to look at the next level? */
1486 if (clk & LVL_CLK_MASK)
1487 break;
1488 /* Shift clock for the next level granularity */
1489 clk >>= LVL_CLK_SHIFT;
1490 }
1491 return levels;
1492}
1493
1494#ifdef CONFIG_NO_HZ_COMMON
1495/*
1496 * Find the next pending bucket of a level. Search from level start (@offset)
1497 * + @clk upwards and if nothing there, search from start of the level
1498 * (@offset) up to @offset + clk.
1499 */
1500static int next_pending_bucket(struct timer_base *base, unsigned offset,
1501 unsigned clk)
1502{
1503 unsigned pos, start = offset + clk;
1504 unsigned end = offset + LVL_SIZE;
1505
1506 pos = find_next_bit(base->pending_map, end, start);
1507 if (pos < end)
1508 return pos - start;
1509
1510 pos = find_next_bit(base->pending_map, start, offset);
1511 return pos < start ? pos + LVL_SIZE - start : -1;
1512}
1513
1514/*
1515 * Search the first expiring timer in the various clock levels. Caller must
1516 * hold base->lock.
1517 */
1518static unsigned long __next_timer_interrupt(struct timer_base *base)
1519{
1520 unsigned long clk, next, adj;
1521 unsigned lvl, offset = 0;
1522
1523 next = base->clk + NEXT_TIMER_MAX_DELTA;
1524 clk = base->clk;
1525 for (lvl = 0; lvl < LVL_DEPTH; lvl++, offset += LVL_SIZE) {
1526 int pos = next_pending_bucket(base, offset, clk & LVL_MASK);
1527
1528 if (pos >= 0) {
1529 unsigned long tmp = clk + (unsigned long) pos;
1530
1531 tmp <<= LVL_SHIFT(lvl);
1532 if (time_before(tmp, next))
1533 next = tmp;
1534 }
1535 /*
1536 * Clock for the next level. If the current level clock lower
1537 * bits are zero, we look at the next level as is. If not we
1538 * need to advance it by one because that's going to be the
1539 * next expiring bucket in that level. base->clk is the next
1540 * expiring jiffie. So in case of:
1541 *
1542 * LVL5 LVL4 LVL3 LVL2 LVL1 LVL0
1543 * 0 0 0 0 0 0
1544 *
1545 * we have to look at all levels @index 0. With
1546 *
1547 * LVL5 LVL4 LVL3 LVL2 LVL1 LVL0
1548 * 0 0 0 0 0 2
1549 *
1550 * LVL0 has the next expiring bucket @index 2. The upper
1551 * levels have the next expiring bucket @index 1.
1552 *
1553 * In case that the propagation wraps the next level the same
1554 * rules apply:
1555 *
1556 * LVL5 LVL4 LVL3 LVL2 LVL1 LVL0
1557 * 0 0 0 0 F 2
1558 *
1559 * So after looking at LVL0 we get:
1560 *
1561 * LVL5 LVL4 LVL3 LVL2 LVL1
1562 * 0 0 0 1 0
1563 *
1564 * So no propagation from LVL1 to LVL2 because that happened
1565 * with the add already, but then we need to propagate further
1566 * from LVL2 to LVL3.
1567 *
1568 * So the simple check whether the lower bits of the current
1569 * level are 0 or not is sufficient for all cases.
1570 */
1571 adj = clk & LVL_CLK_MASK ? 1 : 0;
1572 clk >>= LVL_CLK_SHIFT;
1573 clk += adj;
1574 }
1575 return next;
1576}
1577
1578/*
1579 * Check, if the next hrtimer event is before the next timer wheel
1580 * event:
1581 */
1582static u64 cmp_next_hrtimer_event(u64 basem, u64 expires)
1583{
1584 u64 nextevt = hrtimer_get_next_event();
1585
1586 /*
1587 * If high resolution timers are enabled
1588 * hrtimer_get_next_event() returns KTIME_MAX.
1589 */
1590 if (expires <= nextevt)
1591 return expires;
1592
1593 /*
1594 * If the next timer is already expired, return the tick base
1595 * time so the tick is fired immediately.
1596 */
1597 if (nextevt <= basem)
1598 return basem;
1599
1600 /*
1601 * Round up to the next jiffie. High resolution timers are
1602 * off, so the hrtimers are expired in the tick and we need to
1603 * make sure that this tick really expires the timer to avoid
1604 * a ping pong of the nohz stop code.
1605 *
1606 * Use DIV_ROUND_UP_ULL to prevent gcc calling __divdi3
1607 */
1608 return DIV_ROUND_UP_ULL(nextevt, TICK_NSEC) * TICK_NSEC;
1609}
1610
1611/**
1612 * get_next_timer_interrupt - return the time (clock mono) of the next timer
1613 * @basej: base time jiffies
1614 * @basem: base time clock monotonic
1615 *
1616 * Returns the tick aligned clock monotonic time of the next pending
1617 * timer or KTIME_MAX if no timer is pending.
1618 */
1619u64 get_next_timer_interrupt(unsigned long basej, u64 basem)
1620{
1621 struct timer_base *base = this_cpu_ptr(&timer_bases[BASE_STD]);
1622 u64 expires = KTIME_MAX;
1623 unsigned long nextevt;
1624 bool is_max_delta;
1625
1626 /*
1627 * Pretend that there is no timer pending if the cpu is offline.
1628 * Possible pending timers will be migrated later to an active cpu.
1629 */
1630 if (cpu_is_offline(smp_processor_id()))
1631 return expires;
1632
1633 raw_spin_lock(&base->lock);
1634 nextevt = __next_timer_interrupt(base);
1635 is_max_delta = (nextevt == base->clk + NEXT_TIMER_MAX_DELTA);
1636 base->next_expiry = nextevt;
1637 /*
1638 * We have a fresh next event. Check whether we can forward the
1639 * base. We can only do that when @basej is past base->clk
1640 * otherwise we might rewind base->clk.
1641 */
1642 if (time_after(basej, base->clk)) {
1643 if (time_after(nextevt, basej))
1644 base->clk = basej;
1645 else if (time_after(nextevt, base->clk))
1646 base->clk = nextevt;
1647 }
1648
1649 if (time_before_eq(nextevt, basej)) {
1650 expires = basem;
1651 base->is_idle = false;
1652 } else {
1653 if (!is_max_delta)
1654 expires = basem + (u64)(nextevt - basej) * TICK_NSEC;
1655 /*
1656 * If we expect to sleep more than a tick, mark the base idle.
1657 * Also the tick is stopped so any added timer must forward
1658 * the base clk itself to keep granularity small. This idle
1659 * logic is only maintained for the BASE_STD base, deferrable
1660 * timers may still see large granularity skew (by design).
1661 */
1662 if ((expires - basem) > TICK_NSEC) {
1663 base->must_forward_clk = true;
1664 base->is_idle = true;
1665 }
1666 }
1667 raw_spin_unlock(&base->lock);
1668
1669 return cmp_next_hrtimer_event(basem, expires);
1670}
1671
1672/**
1673 * timer_clear_idle - Clear the idle state of the timer base
1674 *
1675 * Called with interrupts disabled
1676 */
1677void timer_clear_idle(void)
1678{
1679 struct timer_base *base = this_cpu_ptr(&timer_bases[BASE_STD]);
1680
1681 /*
1682 * We do this unlocked. The worst outcome is a remote enqueue sending
1683 * a pointless IPI, but taking the lock would just make the window for
1684 * sending the IPI a few instructions smaller for the cost of taking
1685 * the lock in the exit from idle path.
1686 */
1687 base->is_idle = false;
1688}
1689
1690static int collect_expired_timers(struct timer_base *base,
1691 struct hlist_head *heads)
1692{
1693 unsigned long now = READ_ONCE(jiffies);
1694
1695 /*
1696 * NOHZ optimization. After a long idle sleep we need to forward the
1697 * base to current jiffies. Avoid a loop by searching the bitfield for
1698 * the next expiring timer.
1699 */
1700 if ((long)(now - base->clk) > 2) {
1701 unsigned long next = __next_timer_interrupt(base);
1702
1703 /*
1704 * If the next timer is ahead of time forward to current
1705 * jiffies, otherwise forward to the next expiry time:
1706 */
1707 if (time_after(next, now)) {
1708 /*
1709 * The call site will increment base->clk and then
1710 * terminate the expiry loop immediately.
1711 */
1712 base->clk = now;
1713 return 0;
1714 }
1715 base->clk = next;
1716 }
1717 return __collect_expired_timers(base, heads);
1718}
1719#else
1720static inline int collect_expired_timers(struct timer_base *base,
1721 struct hlist_head *heads)
1722{
1723 return __collect_expired_timers(base, heads);
1724}
1725#endif
1726
1727/*
1728 * Called from the timer interrupt handler to charge one tick to the current
1729 * process. user_tick is 1 if the tick is user time, 0 for system.
1730 */
1731void update_process_times(int user_tick)
1732{
1733 struct task_struct *p = current;
1734
1735 /* Note: this timer irq context must be accounted for as well. */
1736 account_process_tick(p, user_tick);
1737 run_local_timers();
1738 rcu_sched_clock_irq(user_tick);
1739#ifdef CONFIG_IRQ_WORK
1740 if (in_irq())
1741 irq_work_tick();
1742#endif
1743 scheduler_tick();
1744 if (IS_ENABLED(CONFIG_POSIX_TIMERS))
1745 run_posix_cpu_timers();
1746
1747 /* The current CPU might make use of net randoms without receiving IRQs
1748 * to renew them often enough. Let's update the net_rand_state from a
1749 * non-constant value that's not affine to the number of calls to make
1750 * sure it's updated when there's some activity (we don't care in idle).
1751 */
1752 this_cpu_add(net_rand_state.s1, rol32(jiffies, 24) + user_tick);
1753}
1754
1755/**
1756 * __run_timers - run all expired timers (if any) on this CPU.
1757 * @base: the timer vector to be processed.
1758 */
1759static inline void __run_timers(struct timer_base *base)
1760{
1761 struct hlist_head heads[LVL_DEPTH];
1762 int levels;
1763
1764 if (!time_after_eq(jiffies, base->clk))
1765 return;
1766
1767 timer_base_lock_expiry(base);
1768 raw_spin_lock_irq(&base->lock);
1769
1770 /*
1771 * timer_base::must_forward_clk must be cleared before running
1772 * timers so that any timer functions that call mod_timer() will
1773 * not try to forward the base. Idle tracking / clock forwarding
1774 * logic is only used with BASE_STD timers.
1775 *
1776 * The must_forward_clk flag is cleared unconditionally also for
1777 * the deferrable base. The deferrable base is not affected by idle
1778 * tracking and never forwarded, so clearing the flag is a NOOP.
1779 *
1780 * The fact that the deferrable base is never forwarded can cause
1781 * large variations in granularity for deferrable timers, but they
1782 * can be deferred for long periods due to idle anyway.
1783 */
1784 base->must_forward_clk = false;
1785
1786 while (time_after_eq(jiffies, base->clk)) {
1787
1788 levels = collect_expired_timers(base, heads);
1789 base->clk++;
1790
1791 while (levels--)
1792 expire_timers(base, heads + levels);
1793 }
1794 raw_spin_unlock_irq(&base->lock);
1795 timer_base_unlock_expiry(base);
1796}
1797
1798/*
1799 * This function runs timers and the timer-tq in bottom half context.
1800 */
1801static __latent_entropy void run_timer_softirq(struct softirq_action *h)
1802{
1803 struct timer_base *base = this_cpu_ptr(&timer_bases[BASE_STD]);
1804
1805 __run_timers(base);
1806 if (IS_ENABLED(CONFIG_NO_HZ_COMMON))
1807 __run_timers(this_cpu_ptr(&timer_bases[BASE_DEF]));
1808}
1809
1810/*
1811 * Called by the local, per-CPU timer interrupt on SMP.
1812 */
1813void run_local_timers(void)
1814{
1815 struct timer_base *base = this_cpu_ptr(&timer_bases[BASE_STD]);
1816
1817 hrtimer_run_queues();
1818 /* Raise the softirq only if required. */
1819 if (time_before(jiffies, base->clk)) {
1820 if (!IS_ENABLED(CONFIG_NO_HZ_COMMON))
1821 return;
1822 /* CPU is awake, so check the deferrable base. */
1823 base++;
1824 if (time_before(jiffies, base->clk))
1825 return;
1826 }
1827 raise_softirq(TIMER_SOFTIRQ);
1828}
1829
1830/*
1831 * Since schedule_timeout()'s timer is defined on the stack, it must store
1832 * the target task on the stack as well.
1833 */
1834struct process_timer {
1835 struct timer_list timer;
1836 struct task_struct *task;
1837};
1838
1839static void process_timeout(struct timer_list *t)
1840{
1841 struct process_timer *timeout = from_timer(timeout, t, timer);
1842
1843 wake_up_process(timeout->task);
1844}
1845
1846/**
1847 * schedule_timeout - sleep until timeout
1848 * @timeout: timeout value in jiffies
1849 *
1850 * Make the current task sleep until @timeout jiffies have elapsed.
1851 * The function behavior depends on the current task state
1852 * (see also set_current_state() description):
1853 *
1854 * %TASK_RUNNING - the scheduler is called, but the task does not sleep
1855 * at all. That happens because sched_submit_work() does nothing for
1856 * tasks in %TASK_RUNNING state.
1857 *
1858 * %TASK_UNINTERRUPTIBLE - at least @timeout jiffies are guaranteed to
1859 * pass before the routine returns unless the current task is explicitly
1860 * woken up, (e.g. by wake_up_process()).
1861 *
1862 * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
1863 * delivered to the current task or the current task is explicitly woken
1864 * up.
1865 *
1866 * The current task state is guaranteed to be %TASK_RUNNING when this
1867 * routine returns.
1868 *
1869 * Specifying a @timeout value of %MAX_SCHEDULE_TIMEOUT will schedule
1870 * the CPU away without a bound on the timeout. In this case the return
1871 * value will be %MAX_SCHEDULE_TIMEOUT.
1872 *
1873 * Returns 0 when the timer has expired otherwise the remaining time in
1874 * jiffies will be returned. In all cases the return value is guaranteed
1875 * to be non-negative.
1876 */
1877signed long __sched schedule_timeout(signed long timeout)
1878{
1879 struct process_timer timer;
1880 unsigned long expire;
1881
1882 switch (timeout)
1883 {
1884 case MAX_SCHEDULE_TIMEOUT:
1885 /*
1886 * These two special cases are useful to be comfortable
1887 * in the caller. Nothing more. We could take
1888 * MAX_SCHEDULE_TIMEOUT from one of the negative value
1889 * but I' d like to return a valid offset (>=0) to allow
1890 * the caller to do everything it want with the retval.
1891 */
1892 schedule();
1893 goto out;
1894 default:
1895 /*
1896 * Another bit of PARANOID. Note that the retval will be
1897 * 0 since no piece of kernel is supposed to do a check
1898 * for a negative retval of schedule_timeout() (since it
1899 * should never happens anyway). You just have the printk()
1900 * that will tell you if something is gone wrong and where.
1901 */
1902 if (timeout < 0) {
1903 printk(KERN_ERR "schedule_timeout: wrong timeout "
1904 "value %lx\n", timeout);
1905 dump_stack();
1906 current->state = TASK_RUNNING;
1907 goto out;
1908 }
1909 }
1910
1911 expire = timeout + jiffies;
1912
1913 timer.task = current;
1914 timer_setup_on_stack(&timer.timer, process_timeout, 0);
1915 __mod_timer(&timer.timer, expire, MOD_TIMER_NOTPENDING);
1916 schedule();
1917 del_singleshot_timer_sync(&timer.timer);
1918
1919 /* Remove the timer from the object tracker */
1920 destroy_timer_on_stack(&timer.timer);
1921
1922 timeout = expire - jiffies;
1923
1924 out:
1925 return timeout < 0 ? 0 : timeout;
1926}
1927EXPORT_SYMBOL(schedule_timeout);
1928
1929/*
1930 * We can use __set_current_state() here because schedule_timeout() calls
1931 * schedule() unconditionally.
1932 */
1933signed long __sched schedule_timeout_interruptible(signed long timeout)
1934{
1935 __set_current_state(TASK_INTERRUPTIBLE);
1936 return schedule_timeout(timeout);
1937}
1938EXPORT_SYMBOL(schedule_timeout_interruptible);
1939
1940signed long __sched schedule_timeout_killable(signed long timeout)
1941{
1942 __set_current_state(TASK_KILLABLE);
1943 return schedule_timeout(timeout);
1944}
1945EXPORT_SYMBOL(schedule_timeout_killable);
1946
1947signed long __sched schedule_timeout_uninterruptible(signed long timeout)
1948{
1949 __set_current_state(TASK_UNINTERRUPTIBLE);
1950 return schedule_timeout(timeout);
1951}
1952EXPORT_SYMBOL(schedule_timeout_uninterruptible);
1953
1954/*
1955 * Like schedule_timeout_uninterruptible(), except this task will not contribute
1956 * to load average.
1957 */
1958signed long __sched schedule_timeout_idle(signed long timeout)
1959{
1960 __set_current_state(TASK_IDLE);
1961 return schedule_timeout(timeout);
1962}
1963EXPORT_SYMBOL(schedule_timeout_idle);
1964
1965#ifdef CONFIG_HOTPLUG_CPU
1966static void migrate_timer_list(struct timer_base *new_base, struct hlist_head *head)
1967{
1968 struct timer_list *timer;
1969 int cpu = new_base->cpu;
1970
1971 while (!hlist_empty(head)) {
1972 timer = hlist_entry(head->first, struct timer_list, entry);
1973 detach_timer(timer, false);
1974 timer->flags = (timer->flags & ~TIMER_BASEMASK) | cpu;
1975 internal_add_timer(new_base, timer);
1976 }
1977}
1978
1979int timers_prepare_cpu(unsigned int cpu)
1980{
1981 struct timer_base *base;
1982 int b;
1983
1984 for (b = 0; b < NR_BASES; b++) {
1985 base = per_cpu_ptr(&timer_bases[b], cpu);
1986 base->clk = jiffies;
1987 base->next_expiry = base->clk + NEXT_TIMER_MAX_DELTA;
1988 base->is_idle = false;
1989 base->must_forward_clk = true;
1990 }
1991 return 0;
1992}
1993
1994int timers_dead_cpu(unsigned int cpu)
1995{
1996 struct timer_base *old_base;
1997 struct timer_base *new_base;
1998 int b, i;
1999
2000 BUG_ON(cpu_online(cpu));
2001
2002 for (b = 0; b < NR_BASES; b++) {
2003 old_base = per_cpu_ptr(&timer_bases[b], cpu);
2004 new_base = get_cpu_ptr(&timer_bases[b]);
2005 /*
2006 * The caller is globally serialized and nobody else
2007 * takes two locks at once, deadlock is not possible.
2008 */
2009 raw_spin_lock_irq(&new_base->lock);
2010 raw_spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);
2011
2012 /*
2013 * The current CPUs base clock might be stale. Update it
2014 * before moving the timers over.
2015 */
2016 forward_timer_base(new_base);
2017
2018 BUG_ON(old_base->running_timer);
2019
2020 for (i = 0; i < WHEEL_SIZE; i++)
2021 migrate_timer_list(new_base, old_base->vectors + i);
2022
2023 raw_spin_unlock(&old_base->lock);
2024 raw_spin_unlock_irq(&new_base->lock);
2025 put_cpu_ptr(&timer_bases);
2026 }
2027 return 0;
2028}
2029
2030#endif /* CONFIG_HOTPLUG_CPU */
2031
2032static void __init init_timer_cpu(int cpu)
2033{
2034 struct timer_base *base;
2035 int i;
2036
2037 for (i = 0; i < NR_BASES; i++) {
2038 base = per_cpu_ptr(&timer_bases[i], cpu);
2039 base->cpu = cpu;
2040 raw_spin_lock_init(&base->lock);
2041 base->clk = jiffies;
2042 timer_base_init_expiry_lock(base);
2043 }
2044}
2045
2046static void __init init_timer_cpus(void)
2047{
2048 int cpu;
2049
2050 for_each_possible_cpu(cpu)
2051 init_timer_cpu(cpu);
2052}
2053
2054void __init init_timers(void)
2055{
2056 init_timer_cpus();
2057 open_softirq(TIMER_SOFTIRQ, run_timer_softirq);
2058}
2059
2060/**
2061 * msleep - sleep safely even with waitqueue interruptions
2062 * @msecs: Time in milliseconds to sleep for
2063 */
2064void msleep(unsigned int msecs)
2065{
2066 unsigned long timeout = msecs_to_jiffies(msecs) + 1;
2067
2068 while (timeout)
2069 timeout = schedule_timeout_uninterruptible(timeout);
2070}
2071
2072EXPORT_SYMBOL(msleep);
2073
2074/**
2075 * msleep_interruptible - sleep waiting for signals
2076 * @msecs: Time in milliseconds to sleep for
2077 */
2078unsigned long msleep_interruptible(unsigned int msecs)
2079{
2080 unsigned long timeout = msecs_to_jiffies(msecs) + 1;
2081
2082 while (timeout && !signal_pending(current))
2083 timeout = schedule_timeout_interruptible(timeout);
2084 return jiffies_to_msecs(timeout);
2085}
2086
2087EXPORT_SYMBOL(msleep_interruptible);
2088
2089/**
2090 * usleep_range - Sleep for an approximate time
2091 * @min: Minimum time in usecs to sleep
2092 * @max: Maximum time in usecs to sleep
2093 *
2094 * In non-atomic context where the exact wakeup time is flexible, use
2095 * usleep_range() instead of udelay(). The sleep improves responsiveness
2096 * by avoiding the CPU-hogging busy-wait of udelay(), and the range reduces
2097 * power usage by allowing hrtimers to take advantage of an already-
2098 * scheduled interrupt instead of scheduling a new one just for this sleep.
2099 */
2100void __sched usleep_range(unsigned long min, unsigned long max)
2101{
2102 ktime_t exp = ktime_add_us(ktime_get(), min);
2103 u64 delta = (u64)(max - min) * NSEC_PER_USEC;
2104
2105 for (;;) {
2106 __set_current_state(TASK_UNINTERRUPTIBLE);
2107 /* Do not return before the requested sleep time has elapsed */
2108 if (!schedule_hrtimeout_range(&exp, delta, HRTIMER_MODE_ABS))
2109 break;
2110 }
2111}
2112EXPORT_SYMBOL(usleep_range);