Root/kernel/timer.c

1/*
2 * linux/kernel/timer.c
3 *
4 * Kernel internal timers, basic process system calls
5 *
6 * Copyright (C) 1991, 1992 Linus Torvalds
7 *
8 * 1997-01-28 Modified by Finn Arne Gangstad to make timers scale better.
9 *
10 * 1997-09-10 Updated NTP code according to technical memorandum Jan '96
11 * "A Kernel Model for Precision Timekeeping" by Dave Mills
12 * 1998-12-24 Fixed a xtime SMP race (we need the xtime_lock rw spinlock to
13 * serialize accesses to xtime/lost_ticks).
14 * Copyright (C) 1998 Andrea Arcangeli
15 * 1999-03-10 Improved NTP compatibility by Ulrich Windl
16 * 2002-05-31 Move sys_sysinfo here and make its locking sane, Robert Love
17 * 2000-10-05 Implemented scalable SMP per-CPU timer handling.
18 * Copyright (C) 2000, 2001, 2002 Ingo Molnar
19 * Designed by David S. Miller, Alexey Kuznetsov and Ingo Molnar
20 */
21
22#include <linux/kernel_stat.h>
23#include <linux/module.h>
24#include <linux/interrupt.h>
25#include <linux/percpu.h>
26#include <linux/init.h>
27#include <linux/mm.h>
28#include <linux/swap.h>
29#include <linux/pid_namespace.h>
30#include <linux/notifier.h>
31#include <linux/thread_info.h>
32#include <linux/time.h>
33#include <linux/jiffies.h>
34#include <linux/posix-timers.h>
35#include <linux/cpu.h>
36#include <linux/syscalls.h>
37#include <linux/delay.h>
38#include <linux/tick.h>
39#include <linux/kallsyms.h>
40#include <linux/perf_event.h>
41#include <linux/sched.h>
42#include <linux/slab.h>
43
44#include <asm/uaccess.h>
45#include <asm/unistd.h>
46#include <asm/div64.h>
47#include <asm/timex.h>
48#include <asm/io.h>
49
50#define CREATE_TRACE_POINTS
51#include <trace/events/timer.h>
52
53u64 jiffies_64 __cacheline_aligned_in_smp = INITIAL_JIFFIES;
54
55EXPORT_SYMBOL(jiffies_64);
56
57/*
58 * per-CPU timer vector definitions:
59 */
60#define TVN_BITS (CONFIG_BASE_SMALL ? 4 : 6)
61#define TVR_BITS (CONFIG_BASE_SMALL ? 6 : 8)
62#define TVN_SIZE (1 << TVN_BITS)
63#define TVR_SIZE (1 << TVR_BITS)
64#define TVN_MASK (TVN_SIZE - 1)
65#define TVR_MASK (TVR_SIZE - 1)
66
67struct tvec {
68    struct list_head vec[TVN_SIZE];
69};
70
71struct tvec_root {
72    struct list_head vec[TVR_SIZE];
73};
74
75struct tvec_base {
76    spinlock_t lock;
77    struct timer_list *running_timer;
78    unsigned long timer_jiffies;
79    unsigned long next_timer;
80    struct tvec_root tv1;
81    struct tvec tv2;
82    struct tvec tv3;
83    struct tvec tv4;
84    struct tvec tv5;
85} ____cacheline_aligned;
86
87struct tvec_base boot_tvec_bases;
88EXPORT_SYMBOL(boot_tvec_bases);
89static DEFINE_PER_CPU(struct tvec_base *, tvec_bases) = &boot_tvec_bases;
90
91/*
92 * Note that all tvec_bases are 2 byte aligned and lower bit of
93 * base in timer_list is guaranteed to be zero. Use the LSB to
94 * indicate whether the timer is deferrable.
95 *
96 * A deferrable timer will work normally when the system is busy, but
97 * will not cause a CPU to come out of idle just to service it; instead,
98 * the timer will be serviced when the CPU eventually wakes up with a
99 * subsequent non-deferrable timer.
100 */
101#define TBASE_DEFERRABLE_FLAG (0x1)
102
103/* Functions below help us manage 'deferrable' flag */
104static inline unsigned int tbase_get_deferrable(struct tvec_base *base)
105{
106    return ((unsigned int)(unsigned long)base & TBASE_DEFERRABLE_FLAG);
107}
108
109static inline struct tvec_base *tbase_get_base(struct tvec_base *base)
110{
111    return ((struct tvec_base *)((unsigned long)base & ~TBASE_DEFERRABLE_FLAG));
112}
113
114static inline void timer_set_deferrable(struct timer_list *timer)
115{
116    timer->base = ((struct tvec_base *)((unsigned long)(timer->base) |
117                       TBASE_DEFERRABLE_FLAG));
118}
119
120static inline void
121timer_set_base(struct timer_list *timer, struct tvec_base *new_base)
122{
123    timer->base = (struct tvec_base *)((unsigned long)(new_base) |
124                      tbase_get_deferrable(timer->base));
125}
126
127static unsigned long round_jiffies_common(unsigned long j, int cpu,
128        bool force_up)
129{
130    int rem;
131    unsigned long original = j;
132
133    /*
134     * We don't want all cpus firing their timers at once hitting the
135     * same lock or cachelines, so we skew each extra cpu with an extra
136     * 3 jiffies. This 3 jiffies came originally from the mm/ code which
137     * already did this.
138     * The skew is done by adding 3*cpunr, then round, then subtract this
139     * extra offset again.
140     */
141    j += cpu * 3;
142
143    rem = j % HZ;
144
145    /*
146     * If the target jiffie is just after a whole second (which can happen
147     * due to delays of the timer irq, long irq off times etc etc) then
148     * we should round down to the whole second, not up. Use 1/4th second
149     * as cutoff for this rounding as an extreme upper bound for this.
150     * But never round down if @force_up is set.
151     */
152    if (rem < HZ/4 && !force_up) /* round down */
153        j = j - rem;
154    else /* round up */
155        j = j - rem + HZ;
156
157    /* now that we have rounded, subtract the extra skew again */
158    j -= cpu * 3;
159
160    if (j <= jiffies) /* rounding ate our timeout entirely; */
161        return original;
162    return j;
163}
164
165/**
166 * __round_jiffies - function to round jiffies to a full second
167 * @j: the time in (absolute) jiffies that should be rounded
168 * @cpu: the processor number on which the timeout will happen
169 *
170 * __round_jiffies() rounds an absolute time in the future (in jiffies)
171 * up or down to (approximately) full seconds. This is useful for timers
172 * for which the exact time they fire does not matter too much, as long as
173 * they fire approximately every X seconds.
174 *
175 * By rounding these timers to whole seconds, all such timers will fire
176 * at the same time, rather than at various times spread out. The goal
177 * of this is to have the CPU wake up less, which saves power.
178 *
179 * The exact rounding is skewed for each processor to avoid all
180 * processors firing at the exact same time, which could lead
181 * to lock contention or spurious cache line bouncing.
182 *
183 * The return value is the rounded version of the @j parameter.
184 */
185unsigned long __round_jiffies(unsigned long j, int cpu)
186{
187    return round_jiffies_common(j, cpu, false);
188}
189EXPORT_SYMBOL_GPL(__round_jiffies);
190
191/**
192 * __round_jiffies_relative - function to round jiffies to a full second
193 * @j: the time in (relative) jiffies that should be rounded
194 * @cpu: the processor number on which the timeout will happen
195 *
196 * __round_jiffies_relative() rounds a time delta in the future (in jiffies)
197 * up or down to (approximately) full seconds. This is useful for timers
198 * for which the exact time they fire does not matter too much, as long as
199 * they fire approximately every X seconds.
200 *
201 * By rounding these timers to whole seconds, all such timers will fire
202 * at the same time, rather than at various times spread out. The goal
203 * of this is to have the CPU wake up less, which saves power.
204 *
205 * The exact rounding is skewed for each processor to avoid all
206 * processors firing at the exact same time, which could lead
207 * to lock contention or spurious cache line bouncing.
208 *
209 * The return value is the rounded version of the @j parameter.
210 */
211unsigned long __round_jiffies_relative(unsigned long j, int cpu)
212{
213    unsigned long j0 = jiffies;
214
215    /* Use j0 because jiffies might change while we run */
216    return round_jiffies_common(j + j0, cpu, false) - j0;
217}
218EXPORT_SYMBOL_GPL(__round_jiffies_relative);
219
220/**
221 * round_jiffies - function to round jiffies to a full second
222 * @j: the time in (absolute) jiffies that should be rounded
223 *
224 * round_jiffies() rounds an absolute time in the future (in jiffies)
225 * up or down to (approximately) full seconds. This is useful for timers
226 * for which the exact time they fire does not matter too much, as long as
227 * they fire approximately every X seconds.
228 *
229 * By rounding these timers to whole seconds, all such timers will fire
230 * at the same time, rather than at various times spread out. The goal
231 * of this is to have the CPU wake up less, which saves power.
232 *
233 * The return value is the rounded version of the @j parameter.
234 */
235unsigned long round_jiffies(unsigned long j)
236{
237    return round_jiffies_common(j, raw_smp_processor_id(), false);
238}
239EXPORT_SYMBOL_GPL(round_jiffies);
240
241/**
242 * round_jiffies_relative - function to round jiffies to a full second
243 * @j: the time in (relative) jiffies that should be rounded
244 *
245 * round_jiffies_relative() rounds a time delta in the future (in jiffies)
246 * up or down to (approximately) full seconds. This is useful for timers
247 * for which the exact time they fire does not matter too much, as long as
248 * they fire approximately every X seconds.
249 *
250 * By rounding these timers to whole seconds, all such timers will fire
251 * at the same time, rather than at various times spread out. The goal
252 * of this is to have the CPU wake up less, which saves power.
253 *
254 * The return value is the rounded version of the @j parameter.
255 */
256unsigned long round_jiffies_relative(unsigned long j)
257{
258    return __round_jiffies_relative(j, raw_smp_processor_id());
259}
260EXPORT_SYMBOL_GPL(round_jiffies_relative);
261
262/**
263 * __round_jiffies_up - function to round jiffies up to a full second
264 * @j: the time in (absolute) jiffies that should be rounded
265 * @cpu: the processor number on which the timeout will happen
266 *
267 * This is the same as __round_jiffies() except that it will never
268 * round down. This is useful for timeouts for which the exact time
269 * of firing does not matter too much, as long as they don't fire too
270 * early.
271 */
272unsigned long __round_jiffies_up(unsigned long j, int cpu)
273{
274    return round_jiffies_common(j, cpu, true);
275}
276EXPORT_SYMBOL_GPL(__round_jiffies_up);
277
278/**
279 * __round_jiffies_up_relative - function to round jiffies up to a full second
280 * @j: the time in (relative) jiffies that should be rounded
281 * @cpu: the processor number on which the timeout will happen
282 *
283 * This is the same as __round_jiffies_relative() except that it will never
284 * round down. This is useful for timeouts for which the exact time
285 * of firing does not matter too much, as long as they don't fire too
286 * early.
287 */
288unsigned long __round_jiffies_up_relative(unsigned long j, int cpu)
289{
290    unsigned long j0 = jiffies;
291
292    /* Use j0 because jiffies might change while we run */
293    return round_jiffies_common(j + j0, cpu, true) - j0;
294}
295EXPORT_SYMBOL_GPL(__round_jiffies_up_relative);
296
297/**
298 * round_jiffies_up - function to round jiffies up to a full second
299 * @j: the time in (absolute) jiffies that should be rounded
300 *
301 * This is the same as round_jiffies() except that it will never
302 * round down. This is useful for timeouts for which the exact time
303 * of firing does not matter too much, as long as they don't fire too
304 * early.
305 */
306unsigned long round_jiffies_up(unsigned long j)
307{
308    return round_jiffies_common(j, raw_smp_processor_id(), true);
309}
310EXPORT_SYMBOL_GPL(round_jiffies_up);
311
312/**
313 * round_jiffies_up_relative - function to round jiffies up to a full second
314 * @j: the time in (relative) jiffies that should be rounded
315 *
316 * This is the same as round_jiffies_relative() except that it will never
317 * round down. This is useful for timeouts for which the exact time
318 * of firing does not matter too much, as long as they don't fire too
319 * early.
320 */
321unsigned long round_jiffies_up_relative(unsigned long j)
322{
323    return __round_jiffies_up_relative(j, raw_smp_processor_id());
324}
325EXPORT_SYMBOL_GPL(round_jiffies_up_relative);
326
327/**
328 * set_timer_slack - set the allowed slack for a timer
329 * @timer: the timer to be modified
330 * @slack_hz: the amount of time (in jiffies) allowed for rounding
331 *
332 * Set the amount of time, in jiffies, that a certain timer has
333 * in terms of slack. By setting this value, the timer subsystem
334 * will schedule the actual timer somewhere between
335 * the time mod_timer() asks for, and that time plus the slack.
336 *
337 * By setting the slack to -1, a percentage of the delay is used
338 * instead.
339 */
340void set_timer_slack(struct timer_list *timer, int slack_hz)
341{
342    timer->slack = slack_hz;
343}
344EXPORT_SYMBOL_GPL(set_timer_slack);
345
346
347static inline void set_running_timer(struct tvec_base *base,
348                    struct timer_list *timer)
349{
350#ifdef CONFIG_SMP
351    base->running_timer = timer;
352#endif
353}
354
355static void internal_add_timer(struct tvec_base *base, struct timer_list *timer)
356{
357    unsigned long expires = timer->expires;
358    unsigned long idx = expires - base->timer_jiffies;
359    struct list_head *vec;
360
361    if (idx < TVR_SIZE) {
362        int i = expires & TVR_MASK;
363        vec = base->tv1.vec + i;
364    } else if (idx < 1 << (TVR_BITS + TVN_BITS)) {
365        int i = (expires >> TVR_BITS) & TVN_MASK;
366        vec = base->tv2.vec + i;
367    } else if (idx < 1 << (TVR_BITS + 2 * TVN_BITS)) {
368        int i = (expires >> (TVR_BITS + TVN_BITS)) & TVN_MASK;
369        vec = base->tv3.vec + i;
370    } else if (idx < 1 << (TVR_BITS + 3 * TVN_BITS)) {
371        int i = (expires >> (TVR_BITS + 2 * TVN_BITS)) & TVN_MASK;
372        vec = base->tv4.vec + i;
373    } else if ((signed long) idx < 0) {
374        /*
375         * Can happen if you add a timer with expires == jiffies,
376         * or you set a timer to go off in the past
377         */
378        vec = base->tv1.vec + (base->timer_jiffies & TVR_MASK);
379    } else {
380        int i;
381        /* If the timeout is larger than 0xffffffff on 64-bit
382         * architectures then we use the maximum timeout:
383         */
384        if (idx > 0xffffffffUL) {
385            idx = 0xffffffffUL;
386            expires = idx + base->timer_jiffies;
387        }
388        i = (expires >> (TVR_BITS + 3 * TVN_BITS)) & TVN_MASK;
389        vec = base->tv5.vec + i;
390    }
391    /*
392     * Timers are FIFO:
393     */
394    list_add_tail(&timer->entry, vec);
395}
396
397#ifdef CONFIG_TIMER_STATS
398void __timer_stats_timer_set_start_info(struct timer_list *timer, void *addr)
399{
400    if (timer->start_site)
401        return;
402
403    timer->start_site = addr;
404    memcpy(timer->start_comm, current->comm, TASK_COMM_LEN);
405    timer->start_pid = current->pid;
406}
407
408static void timer_stats_account_timer(struct timer_list *timer)
409{
410    unsigned int flag = 0;
411
412    if (likely(!timer->start_site))
413        return;
414    if (unlikely(tbase_get_deferrable(timer->base)))
415        flag |= TIMER_STATS_FLAG_DEFERRABLE;
416
417    timer_stats_update_stats(timer, timer->start_pid, timer->start_site,
418                 timer->function, timer->start_comm, flag);
419}
420
421#else
422static void timer_stats_account_timer(struct timer_list *timer) {}
423#endif
424
425#ifdef CONFIG_DEBUG_OBJECTS_TIMERS
426
427static struct debug_obj_descr timer_debug_descr;
428
429/*
430 * fixup_init is called when:
431 * - an active object is initialized
432 */
433static int timer_fixup_init(void *addr, enum debug_obj_state state)
434{
435    struct timer_list *timer = addr;
436
437    switch (state) {
438    case ODEBUG_STATE_ACTIVE:
439        del_timer_sync(timer);
440        debug_object_init(timer, &timer_debug_descr);
441        return 1;
442    default:
443        return 0;
444    }
445}
446
447/*
448 * fixup_activate is called when:
449 * - an active object is activated
450 * - an unknown object is activated (might be a statically initialized object)
451 */
452static int timer_fixup_activate(void *addr, enum debug_obj_state state)
453{
454    struct timer_list *timer = addr;
455
456    switch (state) {
457
458    case ODEBUG_STATE_NOTAVAILABLE:
459        /*
460         * This is not really a fixup. The timer was
461         * statically initialized. We just make sure that it
462         * is tracked in the object tracker.
463         */
464        if (timer->entry.next == NULL &&
465            timer->entry.prev == TIMER_ENTRY_STATIC) {
466            debug_object_init(timer, &timer_debug_descr);
467            debug_object_activate(timer, &timer_debug_descr);
468            return 0;
469        } else {
470            WARN_ON_ONCE(1);
471        }
472        return 0;
473
474    case ODEBUG_STATE_ACTIVE:
475        WARN_ON(1);
476
477    default:
478        return 0;
479    }
480}
481
482/*
483 * fixup_free is called when:
484 * - an active object is freed
485 */
486static int timer_fixup_free(void *addr, enum debug_obj_state state)
487{
488    struct timer_list *timer = addr;
489
490    switch (state) {
491    case ODEBUG_STATE_ACTIVE:
492        del_timer_sync(timer);
493        debug_object_free(timer, &timer_debug_descr);
494        return 1;
495    default:
496        return 0;
497    }
498}
499
500static struct debug_obj_descr timer_debug_descr = {
501    .name = "timer_list",
502    .fixup_init = timer_fixup_init,
503    .fixup_activate = timer_fixup_activate,
504    .fixup_free = timer_fixup_free,
505};
506
507static inline void debug_timer_init(struct timer_list *timer)
508{
509    debug_object_init(timer, &timer_debug_descr);
510}
511
512static inline void debug_timer_activate(struct timer_list *timer)
513{
514    debug_object_activate(timer, &timer_debug_descr);
515}
516
517static inline void debug_timer_deactivate(struct timer_list *timer)
518{
519    debug_object_deactivate(timer, &timer_debug_descr);
520}
521
522static inline void debug_timer_free(struct timer_list *timer)
523{
524    debug_object_free(timer, &timer_debug_descr);
525}
526
527static void __init_timer(struct timer_list *timer,
528             const char *name,
529             struct lock_class_key *key);
530
531void init_timer_on_stack_key(struct timer_list *timer,
532                 const char *name,
533                 struct lock_class_key *key)
534{
535    debug_object_init_on_stack(timer, &timer_debug_descr);
536    __init_timer(timer, name, key);
537}
538EXPORT_SYMBOL_GPL(init_timer_on_stack_key);
539
540void destroy_timer_on_stack(struct timer_list *timer)
541{
542    debug_object_free(timer, &timer_debug_descr);
543}
544EXPORT_SYMBOL_GPL(destroy_timer_on_stack);
545
546#else
547static inline void debug_timer_init(struct timer_list *timer) { }
548static inline void debug_timer_activate(struct timer_list *timer) { }
549static inline void debug_timer_deactivate(struct timer_list *timer) { }
550#endif
551
552static inline void debug_init(struct timer_list *timer)
553{
554    debug_timer_init(timer);
555    trace_timer_init(timer);
556}
557
558static inline void
559debug_activate(struct timer_list *timer, unsigned long expires)
560{
561    debug_timer_activate(timer);
562    trace_timer_start(timer, expires);
563}
564
565static inline void debug_deactivate(struct timer_list *timer)
566{
567    debug_timer_deactivate(timer);
568    trace_timer_cancel(timer);
569}
570
571static void __init_timer(struct timer_list *timer,
572             const char *name,
573             struct lock_class_key *key)
574{
575    timer->entry.next = NULL;
576    timer->base = __raw_get_cpu_var(tvec_bases);
577    timer->slack = -1;
578#ifdef CONFIG_TIMER_STATS
579    timer->start_site = NULL;
580    timer->start_pid = -1;
581    memset(timer->start_comm, 0, TASK_COMM_LEN);
582#endif
583    lockdep_init_map(&timer->lockdep_map, name, key, 0);
584}
585
586void setup_deferrable_timer_on_stack_key(struct timer_list *timer,
587                     const char *name,
588                     struct lock_class_key *key,
589                     void (*function)(unsigned long),
590                     unsigned long data)
591{
592    timer->function = function;
593    timer->data = data;
594    init_timer_on_stack_key(timer, name, key);
595    timer_set_deferrable(timer);
596}
597EXPORT_SYMBOL_GPL(setup_deferrable_timer_on_stack_key);
598
599/**
600 * init_timer_key - initialize a timer
601 * @timer: the timer to be initialized
602 * @name: name of the timer
603 * @key: lockdep class key of the fake lock used for tracking timer
604 * sync lock dependencies
605 *
606 * init_timer_key() must be done to a timer prior calling *any* of the
607 * other timer functions.
608 */
609void init_timer_key(struct timer_list *timer,
610            const char *name,
611            struct lock_class_key *key)
612{
613    debug_init(timer);
614    __init_timer(timer, name, key);
615}
616EXPORT_SYMBOL(init_timer_key);
617
618void init_timer_deferrable_key(struct timer_list *timer,
619                   const char *name,
620                   struct lock_class_key *key)
621{
622    init_timer_key(timer, name, key);
623    timer_set_deferrable(timer);
624}
625EXPORT_SYMBOL(init_timer_deferrable_key);
626
627static inline void detach_timer(struct timer_list *timer,
628                int clear_pending)
629{
630    struct list_head *entry = &timer->entry;
631
632    debug_deactivate(timer);
633
634    __list_del(entry->prev, entry->next);
635    if (clear_pending)
636        entry->next = NULL;
637    entry->prev = LIST_POISON2;
638}
639
640/*
641 * We are using hashed locking: holding per_cpu(tvec_bases).lock
642 * means that all timers which are tied to this base via timer->base are
643 * locked, and the base itself is locked too.
644 *
645 * So __run_timers/migrate_timers can safely modify all timers which could
646 * be found on ->tvX lists.
647 *
648 * When the timer's base is locked, and the timer removed from list, it is
649 * possible to set timer->base = NULL and drop the lock: the timer remains
650 * locked.
651 */
652static struct tvec_base *lock_timer_base(struct timer_list *timer,
653                    unsigned long *flags)
654    __acquires(timer->base->lock)
655{
656    struct tvec_base *base;
657
658    for (;;) {
659        struct tvec_base *prelock_base = timer->base;
660        base = tbase_get_base(prelock_base);
661        if (likely(base != NULL)) {
662            spin_lock_irqsave(&base->lock, *flags);
663            if (likely(prelock_base == timer->base))
664                return base;
665            /* The timer has migrated to another CPU */
666            spin_unlock_irqrestore(&base->lock, *flags);
667        }
668        cpu_relax();
669    }
670}
671
672static inline int
673__mod_timer(struct timer_list *timer, unsigned long expires,
674                        bool pending_only, int pinned)
675{
676    struct tvec_base *base, *new_base;
677    unsigned long flags;
678    int ret = 0 , cpu;
679
680    timer_stats_timer_set_start_info(timer);
681    BUG_ON(!timer->function);
682
683    base = lock_timer_base(timer, &flags);
684
685    if (timer_pending(timer)) {
686        detach_timer(timer, 0);
687        if (timer->expires == base->next_timer &&
688            !tbase_get_deferrable(timer->base))
689            base->next_timer = base->timer_jiffies;
690        ret = 1;
691    } else {
692        if (pending_only)
693            goto out_unlock;
694    }
695
696    debug_activate(timer, expires);
697
698    cpu = smp_processor_id();
699
700#if defined(CONFIG_NO_HZ) && defined(CONFIG_SMP)
701    if (!pinned && get_sysctl_timer_migration() && idle_cpu(cpu))
702        cpu = get_nohz_timer_target();
703#endif
704    new_base = per_cpu(tvec_bases, cpu);
705
706    if (base != new_base) {
707        /*
708         * We are trying to schedule the timer on the local CPU.
709         * However we can't change timer's base while it is running,
710         * otherwise del_timer_sync() can't detect that the timer's
711         * handler yet has not finished. This also guarantees that
712         * the timer is serialized wrt itself.
713         */
714        if (likely(base->running_timer != timer)) {
715            /* See the comment in lock_timer_base() */
716            timer_set_base(timer, NULL);
717            spin_unlock(&base->lock);
718            base = new_base;
719            spin_lock(&base->lock);
720            timer_set_base(timer, base);
721        }
722    }
723
724    timer->expires = expires;
725    if (time_before(timer->expires, base->next_timer) &&
726        !tbase_get_deferrable(timer->base))
727        base->next_timer = timer->expires;
728    internal_add_timer(base, timer);
729
730out_unlock:
731    spin_unlock_irqrestore(&base->lock, flags);
732
733    return ret;
734}
735
736/**
737 * mod_timer_pending - modify a pending timer's timeout
738 * @timer: the pending timer to be modified
739 * @expires: new timeout in jiffies
740 *
741 * mod_timer_pending() is the same for pending timers as mod_timer(),
742 * but will not re-activate and modify already deleted timers.
743 *
744 * It is useful for unserialized use of timers.
745 */
746int mod_timer_pending(struct timer_list *timer, unsigned long expires)
747{
748    return __mod_timer(timer, expires, true, TIMER_NOT_PINNED);
749}
750EXPORT_SYMBOL(mod_timer_pending);
751
752/*
753 * Decide where to put the timer while taking the slack into account
754 *
755 * Algorithm:
756 * 1) calculate the maximum (absolute) time
757 * 2) calculate the highest bit where the expires and new max are different
758 * 3) use this bit to make a mask
759 * 4) use the bitmask to round down the maximum time, so that all last
760 * bits are zeros
761 */
762static inline
763unsigned long apply_slack(struct timer_list *timer, unsigned long expires)
764{
765    unsigned long expires_limit, mask;
766    int bit;
767
768    expires_limit = expires;
769
770    if (timer->slack >= 0) {
771        expires_limit = expires + timer->slack;
772    } else {
773        unsigned long now = jiffies;
774
775        /* No slack, if already expired else auto slack 0.4% */
776        if (time_after(expires, now))
777            expires_limit = expires + (expires - now)/256;
778    }
779    mask = expires ^ expires_limit;
780    if (mask == 0)
781        return expires;
782
783    bit = find_last_bit(&mask, BITS_PER_LONG);
784
785    mask = (1 << bit) - 1;
786
787    expires_limit = expires_limit & ~(mask);
788
789    return expires_limit;
790}
791
792/**
793 * mod_timer - modify a timer's timeout
794 * @timer: the timer to be modified
795 * @expires: new timeout in jiffies
796 *
797 * mod_timer() is a more efficient way to update the expire field of an
798 * active timer (if the timer is inactive it will be activated)
799 *
800 * mod_timer(timer, expires) is equivalent to:
801 *
802 * del_timer(timer); timer->expires = expires; add_timer(timer);
803 *
804 * Note that if there are multiple unserialized concurrent users of the
805 * same timer, then mod_timer() is the only safe way to modify the timeout,
806 * since add_timer() cannot modify an already running timer.
807 *
808 * The function returns whether it has modified a pending timer or not.
809 * (ie. mod_timer() of an inactive timer returns 0, mod_timer() of an
810 * active timer returns 1.)
811 */
812int mod_timer(struct timer_list *timer, unsigned long expires)
813{
814    /*
815     * This is a common optimization triggered by the
816     * networking code - if the timer is re-modified
817     * to be the same thing then just return:
818     */
819    if (timer_pending(timer) && timer->expires == expires)
820        return 1;
821
822    expires = apply_slack(timer, expires);
823
824    return __mod_timer(timer, expires, false, TIMER_NOT_PINNED);
825}
826EXPORT_SYMBOL(mod_timer);
827
828/**
829 * mod_timer_pinned - modify a timer's timeout
830 * @timer: the timer to be modified
831 * @expires: new timeout in jiffies
832 *
833 * mod_timer_pinned() is a way to update the expire field of an
834 * active timer (if the timer is inactive it will be activated)
835 * and not allow the timer to be migrated to a different CPU.
836 *
837 * mod_timer_pinned(timer, expires) is equivalent to:
838 *
839 * del_timer(timer); timer->expires = expires; add_timer(timer);
840 */
841int mod_timer_pinned(struct timer_list *timer, unsigned long expires)
842{
843    if (timer->expires == expires && timer_pending(timer))
844        return 1;
845
846    return __mod_timer(timer, expires, false, TIMER_PINNED);
847}
848EXPORT_SYMBOL(mod_timer_pinned);
849
850/**
851 * add_timer - start a timer
852 * @timer: the timer to be added
853 *
854 * The kernel will do a ->function(->data) callback from the
855 * timer interrupt at the ->expires point in the future. The
856 * current time is 'jiffies'.
857 *
858 * The timer's ->expires, ->function (and if the handler uses it, ->data)
859 * fields must be set prior calling this function.
860 *
861 * Timers with an ->expires field in the past will be executed in the next
862 * timer tick.
863 */
864void add_timer(struct timer_list *timer)
865{
866    BUG_ON(timer_pending(timer));
867    mod_timer(timer, timer->expires);
868}
869EXPORT_SYMBOL(add_timer);
870
871/**
872 * add_timer_on - start a timer on a particular CPU
873 * @timer: the timer to be added
874 * @cpu: the CPU to start it on
875 *
876 * This is not very scalable on SMP. Double adds are not possible.
877 */
878void add_timer_on(struct timer_list *timer, int cpu)
879{
880    struct tvec_base *base = per_cpu(tvec_bases, cpu);
881    unsigned long flags;
882
883    timer_stats_timer_set_start_info(timer);
884    BUG_ON(timer_pending(timer) || !timer->function);
885    spin_lock_irqsave(&base->lock, flags);
886    timer_set_base(timer, base);
887    debug_activate(timer, timer->expires);
888    if (time_before(timer->expires, base->next_timer) &&
889        !tbase_get_deferrable(timer->base))
890        base->next_timer = timer->expires;
891    internal_add_timer(base, timer);
892    /*
893     * Check whether the other CPU is idle and needs to be
894     * triggered to reevaluate the timer wheel when nohz is
895     * active. We are protected against the other CPU fiddling
896     * with the timer by holding the timer base lock. This also
897     * makes sure that a CPU on the way to idle can not evaluate
898     * the timer wheel.
899     */
900    wake_up_idle_cpu(cpu);
901    spin_unlock_irqrestore(&base->lock, flags);
902}
903EXPORT_SYMBOL_GPL(add_timer_on);
904
905/**
906 * del_timer - deactive a timer.
907 * @timer: the timer to be deactivated
908 *
909 * del_timer() deactivates a timer - this works on both active and inactive
910 * timers.
911 *
912 * The function returns whether it has deactivated a pending timer or not.
913 * (ie. del_timer() of an inactive timer returns 0, del_timer() of an
914 * active timer returns 1.)
915 */
916int del_timer(struct timer_list *timer)
917{
918    struct tvec_base *base;
919    unsigned long flags;
920    int ret = 0;
921
922    timer_stats_timer_clear_start_info(timer);
923    if (timer_pending(timer)) {
924        base = lock_timer_base(timer, &flags);
925        if (timer_pending(timer)) {
926            detach_timer(timer, 1);
927            if (timer->expires == base->next_timer &&
928                !tbase_get_deferrable(timer->base))
929                base->next_timer = base->timer_jiffies;
930            ret = 1;
931        }
932        spin_unlock_irqrestore(&base->lock, flags);
933    }
934
935    return ret;
936}
937EXPORT_SYMBOL(del_timer);
938
939#ifdef CONFIG_SMP
940/**
941 * try_to_del_timer_sync - Try to deactivate a timer
942 * @timer: timer do del
943 *
944 * This function tries to deactivate a timer. Upon successful (ret >= 0)
945 * exit the timer is not queued and the handler is not running on any CPU.
946 *
947 * It must not be called from interrupt contexts.
948 */
949int try_to_del_timer_sync(struct timer_list *timer)
950{
951    struct tvec_base *base;
952    unsigned long flags;
953    int ret = -1;
954
955    base = lock_timer_base(timer, &flags);
956
957    if (base->running_timer == timer)
958        goto out;
959
960    timer_stats_timer_clear_start_info(timer);
961    ret = 0;
962    if (timer_pending(timer)) {
963        detach_timer(timer, 1);
964        if (timer->expires == base->next_timer &&
965            !tbase_get_deferrable(timer->base))
966            base->next_timer = base->timer_jiffies;
967        ret = 1;
968    }
969out:
970    spin_unlock_irqrestore(&base->lock, flags);
971
972    return ret;
973}
974EXPORT_SYMBOL(try_to_del_timer_sync);
975
976/**
977 * del_timer_sync - deactivate a timer and wait for the handler to finish.
978 * @timer: the timer to be deactivated
979 *
980 * This function only differs from del_timer() on SMP: besides deactivating
981 * the timer it also makes sure the handler has finished executing on other
982 * CPUs.
983 *
984 * Synchronization rules: Callers must prevent restarting of the timer,
985 * otherwise this function is meaningless. It must not be called from
986 * interrupt contexts. The caller must not hold locks which would prevent
987 * completion of the timer's handler. The timer's handler must not call
988 * add_timer_on(). Upon exit the timer is not queued and the handler is
989 * not running on any CPU.
990 *
991 * The function returns whether it has deactivated a pending timer or not.
992 */
993int del_timer_sync(struct timer_list *timer)
994{
995#ifdef CONFIG_LOCKDEP
996    unsigned long flags;
997
998    local_irq_save(flags);
999    lock_map_acquire(&timer->lockdep_map);
1000    lock_map_release(&timer->lockdep_map);
1001    local_irq_restore(flags);
1002#endif
1003
1004    for (;;) {
1005        int ret = try_to_del_timer_sync(timer);
1006        if (ret >= 0)
1007            return ret;
1008        cpu_relax();
1009    }
1010}
1011EXPORT_SYMBOL(del_timer_sync);
1012#endif
1013
1014static int cascade(struct tvec_base *base, struct tvec *tv, int index)
1015{
1016    /* cascade all the timers from tv up one level */
1017    struct timer_list *timer, *tmp;
1018    struct list_head tv_list;
1019
1020    list_replace_init(tv->vec + index, &tv_list);
1021
1022    /*
1023     * We are removing _all_ timers from the list, so we
1024     * don't have to detach them individually.
1025     */
1026    list_for_each_entry_safe(timer, tmp, &tv_list, entry) {
1027        BUG_ON(tbase_get_base(timer->base) != base);
1028        internal_add_timer(base, timer);
1029    }
1030
1031    return index;
1032}
1033
1034static void call_timer_fn(struct timer_list *timer, void (*fn)(unsigned long),
1035              unsigned long data)
1036{
1037    int preempt_count = preempt_count();
1038
1039#ifdef CONFIG_LOCKDEP
1040    /*
1041     * It is permissible to free the timer from inside the
1042     * function that is called from it, this we need to take into
1043     * account for lockdep too. To avoid bogus "held lock freed"
1044     * warnings as well as problems when looking into
1045     * timer->lockdep_map, make a copy and use that here.
1046     */
1047    struct lockdep_map lockdep_map = timer->lockdep_map;
1048#endif
1049    /*
1050     * Couple the lock chain with the lock chain at
1051     * del_timer_sync() by acquiring the lock_map around the fn()
1052     * call here and in del_timer_sync().
1053     */
1054    lock_map_acquire(&lockdep_map);
1055
1056    trace_timer_expire_entry(timer);
1057    fn(data);
1058    trace_timer_expire_exit(timer);
1059
1060    lock_map_release(&lockdep_map);
1061
1062    if (preempt_count != preempt_count()) {
1063        WARN_ONCE(1, "timer: %pF preempt leak: %08x -> %08x\n",
1064              fn, preempt_count, preempt_count());
1065        /*
1066         * Restore the preempt count. That gives us a decent
1067         * chance to survive and extract information. If the
1068         * callback kept a lock held, bad luck, but not worse
1069         * than the BUG() we had.
1070         */
1071        preempt_count() = preempt_count;
1072    }
1073}
1074
1075#define INDEX(N) ((base->timer_jiffies >> (TVR_BITS + (N) * TVN_BITS)) & TVN_MASK)
1076
1077/**
1078 * __run_timers - run all expired timers (if any) on this CPU.
1079 * @base: the timer vector to be processed.
1080 *
1081 * This function cascades all vectors and executes all expired timer
1082 * vectors.
1083 */
1084static inline void __run_timers(struct tvec_base *base)
1085{
1086    struct timer_list *timer;
1087
1088    spin_lock_irq(&base->lock);
1089    while (time_after_eq(jiffies, base->timer_jiffies)) {
1090        struct list_head work_list;
1091        struct list_head *head = &work_list;
1092        int index = base->timer_jiffies & TVR_MASK;
1093
1094        /*
1095         * Cascade timers:
1096         */
1097        if (!index &&
1098            (!cascade(base, &base->tv2, INDEX(0))) &&
1099                (!cascade(base, &base->tv3, INDEX(1))) &&
1100                    !cascade(base, &base->tv4, INDEX(2)))
1101            cascade(base, &base->tv5, INDEX(3));
1102        ++base->timer_jiffies;
1103        list_replace_init(base->tv1.vec + index, &work_list);
1104        while (!list_empty(head)) {
1105            void (*fn)(unsigned long);
1106            unsigned long data;
1107
1108            timer = list_first_entry(head, struct timer_list,entry);
1109            fn = timer->function;
1110            data = timer->data;
1111
1112            timer_stats_account_timer(timer);
1113
1114            set_running_timer(base, timer);
1115            detach_timer(timer, 1);
1116
1117            spin_unlock_irq(&base->lock);
1118            call_timer_fn(timer, fn, data);
1119            spin_lock_irq(&base->lock);
1120        }
1121    }
1122    set_running_timer(base, NULL);
1123    spin_unlock_irq(&base->lock);
1124}
1125
1126#ifdef CONFIG_NO_HZ
1127/*
1128 * Find out when the next timer event is due to happen. This
1129 * is used on S/390 to stop all activity when a CPU is idle.
1130 * This function needs to be called with interrupts disabled.
1131 */
1132static unsigned long __next_timer_interrupt(struct tvec_base *base)
1133{
1134    unsigned long timer_jiffies = base->timer_jiffies;
1135    unsigned long expires = timer_jiffies + NEXT_TIMER_MAX_DELTA;
1136    int index, slot, array, found = 0;
1137    struct timer_list *nte;
1138    struct tvec *varray[4];
1139
1140    /* Look for timer events in tv1. */
1141    index = slot = timer_jiffies & TVR_MASK;
1142    do {
1143        list_for_each_entry(nte, base->tv1.vec + slot, entry) {
1144            if (tbase_get_deferrable(nte->base))
1145                continue;
1146
1147            found = 1;
1148            expires = nte->expires;
1149            /* Look at the cascade bucket(s)? */
1150            if (!index || slot < index)
1151                goto cascade;
1152            return expires;
1153        }
1154        slot = (slot + 1) & TVR_MASK;
1155    } while (slot != index);
1156
1157cascade:
1158    /* Calculate the next cascade event */
1159    if (index)
1160        timer_jiffies += TVR_SIZE - index;
1161    timer_jiffies >>= TVR_BITS;
1162
1163    /* Check tv2-tv5. */
1164    varray[0] = &base->tv2;
1165    varray[1] = &base->tv3;
1166    varray[2] = &base->tv4;
1167    varray[3] = &base->tv5;
1168
1169    for (array = 0; array < 4; array++) {
1170        struct tvec *varp = varray[array];
1171
1172        index = slot = timer_jiffies & TVN_MASK;
1173        do {
1174            list_for_each_entry(nte, varp->vec + slot, entry) {
1175                if (tbase_get_deferrable(nte->base))
1176                    continue;
1177
1178                found = 1;
1179                if (time_before(nte->expires, expires))
1180                    expires = nte->expires;
1181            }
1182            /*
1183             * Do we still search for the first timer or are
1184             * we looking up the cascade buckets ?
1185             */
1186            if (found) {
1187                /* Look at the cascade bucket(s)? */
1188                if (!index || slot < index)
1189                    break;
1190                return expires;
1191            }
1192            slot = (slot + 1) & TVN_MASK;
1193        } while (slot != index);
1194
1195        if (index)
1196            timer_jiffies += TVN_SIZE - index;
1197        timer_jiffies >>= TVN_BITS;
1198    }
1199    return expires;
1200}
1201
1202/*
1203 * Check, if the next hrtimer event is before the next timer wheel
1204 * event:
1205 */
1206static unsigned long cmp_next_hrtimer_event(unsigned long now,
1207                        unsigned long expires)
1208{
1209    ktime_t hr_delta = hrtimer_get_next_event();
1210    struct timespec tsdelta;
1211    unsigned long delta;
1212
1213    if (hr_delta.tv64 == KTIME_MAX)
1214        return expires;
1215
1216    /*
1217     * Expired timer available, let it expire in the next tick
1218     */
1219    if (hr_delta.tv64 <= 0)
1220        return now + 1;
1221
1222    tsdelta = ktime_to_timespec(hr_delta);
1223    delta = timespec_to_jiffies(&tsdelta);
1224
1225    /*
1226     * Limit the delta to the max value, which is checked in
1227     * tick_nohz_stop_sched_tick():
1228     */
1229    if (delta > NEXT_TIMER_MAX_DELTA)
1230        delta = NEXT_TIMER_MAX_DELTA;
1231
1232    /*
1233     * Take rounding errors in to account and make sure, that it
1234     * expires in the next tick. Otherwise we go into an endless
1235     * ping pong due to tick_nohz_stop_sched_tick() retriggering
1236     * the timer softirq
1237     */
1238    if (delta < 1)
1239        delta = 1;
1240    now += delta;
1241    if (time_before(now, expires))
1242        return now;
1243    return expires;
1244}
1245
1246/**
1247 * get_next_timer_interrupt - return the jiffy of the next pending timer
1248 * @now: current time (in jiffies)
1249 */
1250unsigned long get_next_timer_interrupt(unsigned long now)
1251{
1252    struct tvec_base *base = __get_cpu_var(tvec_bases);
1253    unsigned long expires;
1254
1255    spin_lock(&base->lock);
1256    if (time_before_eq(base->next_timer, base->timer_jiffies))
1257        base->next_timer = __next_timer_interrupt(base);
1258    expires = base->next_timer;
1259    spin_unlock(&base->lock);
1260
1261    if (time_before_eq(expires, now))
1262        return now;
1263
1264    return cmp_next_hrtimer_event(now, expires);
1265}
1266#endif
1267
1268/*
1269 * Called from the timer interrupt handler to charge one tick to the current
1270 * process. user_tick is 1 if the tick is user time, 0 for system.
1271 */
1272void update_process_times(int user_tick)
1273{
1274    struct task_struct *p = current;
1275    int cpu = smp_processor_id();
1276
1277    /* Note: this timer irq context must be accounted for as well. */
1278    account_process_tick(p, user_tick);
1279    run_local_timers();
1280    rcu_check_callbacks(cpu, user_tick);
1281    printk_tick();
1282    perf_event_do_pending();
1283    scheduler_tick();
1284    run_posix_cpu_timers(p);
1285}
1286
1287/*
1288 * This function runs timers and the timer-tq in bottom half context.
1289 */
1290static void run_timer_softirq(struct softirq_action *h)
1291{
1292    struct tvec_base *base = __get_cpu_var(tvec_bases);
1293
1294    hrtimer_run_pending();
1295
1296    if (time_after_eq(jiffies, base->timer_jiffies))
1297        __run_timers(base);
1298}
1299
1300/*
1301 * Called by the local, per-CPU timer interrupt on SMP.
1302 */
1303void run_local_timers(void)
1304{
1305    hrtimer_run_queues();
1306    raise_softirq(TIMER_SOFTIRQ);
1307}
1308
1309/*
1310 * The 64-bit jiffies value is not atomic - you MUST NOT read it
1311 * without sampling the sequence number in xtime_lock.
1312 * jiffies is defined in the linker script...
1313 */
1314
1315void do_timer(unsigned long ticks)
1316{
1317    jiffies_64 += ticks;
1318    update_wall_time();
1319    calc_global_load();
1320}
1321
1322#ifdef __ARCH_WANT_SYS_ALARM
1323
1324/*
1325 * For backwards compatibility? This can be done in libc so Alpha
1326 * and all newer ports shouldn't need it.
1327 */
1328SYSCALL_DEFINE1(alarm, unsigned int, seconds)
1329{
1330    return alarm_setitimer(seconds);
1331}
1332
1333#endif
1334
1335#ifndef __alpha__
1336
1337/*
1338 * The Alpha uses getxpid, getxuid, and getxgid instead. Maybe this
1339 * should be moved into arch/i386 instead?
1340 */
1341
1342/**
1343 * sys_getpid - return the thread group id of the current process
1344 *
1345 * Note, despite the name, this returns the tgid not the pid. The tgid and
1346 * the pid are identical unless CLONE_THREAD was specified on clone() in
1347 * which case the tgid is the same in all threads of the same group.
1348 *
1349 * This is SMP safe as current->tgid does not change.
1350 */
1351SYSCALL_DEFINE0(getpid)
1352{
1353    return task_tgid_vnr(current);
1354}
1355
1356/*
1357 * Accessing ->real_parent is not SMP-safe, it could
1358 * change from under us. However, we can use a stale
1359 * value of ->real_parent under rcu_read_lock(), see
1360 * release_task()->call_rcu(delayed_put_task_struct).
1361 */
1362SYSCALL_DEFINE0(getppid)
1363{
1364    int pid;
1365
1366    rcu_read_lock();
1367    pid = task_tgid_vnr(current->real_parent);
1368    rcu_read_unlock();
1369
1370    return pid;
1371}
1372
1373SYSCALL_DEFINE0(getuid)
1374{
1375    /* Only we change this so SMP safe */
1376    return current_uid();
1377}
1378
1379SYSCALL_DEFINE0(geteuid)
1380{
1381    /* Only we change this so SMP safe */
1382    return current_euid();
1383}
1384
1385SYSCALL_DEFINE0(getgid)
1386{
1387    /* Only we change this so SMP safe */
1388    return current_gid();
1389}
1390
1391SYSCALL_DEFINE0(getegid)
1392{
1393    /* Only we change this so SMP safe */
1394    return current_egid();
1395}
1396
1397#endif
1398
1399static void process_timeout(unsigned long __data)
1400{
1401    wake_up_process((struct task_struct *)__data);
1402}
1403
1404/**
1405 * schedule_timeout - sleep until timeout
1406 * @timeout: timeout value in jiffies
1407 *
1408 * Make the current task sleep until @timeout jiffies have
1409 * elapsed. The routine will return immediately unless
1410 * the current task state has been set (see set_current_state()).
1411 *
1412 * You can set the task state as follows -
1413 *
1414 * %TASK_UNINTERRUPTIBLE - at least @timeout jiffies are guaranteed to
1415 * pass before the routine returns. The routine will return 0
1416 *
1417 * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
1418 * delivered to the current task. In this case the remaining time
1419 * in jiffies will be returned, or 0 if the timer expired in time
1420 *
1421 * The current task state is guaranteed to be TASK_RUNNING when this
1422 * routine returns.
1423 *
1424 * Specifying a @timeout value of %MAX_SCHEDULE_TIMEOUT will schedule
1425 * the CPU away without a bound on the timeout. In this case the return
1426 * value will be %MAX_SCHEDULE_TIMEOUT.
1427 *
1428 * In all cases the return value is guaranteed to be non-negative.
1429 */
1430signed long __sched schedule_timeout(signed long timeout)
1431{
1432    struct timer_list timer;
1433    unsigned long expire;
1434
1435    switch (timeout)
1436    {
1437    case MAX_SCHEDULE_TIMEOUT:
1438        /*
1439         * These two special cases are useful to be comfortable
1440         * in the caller. Nothing more. We could take
1441         * MAX_SCHEDULE_TIMEOUT from one of the negative value
1442         * but I' d like to return a valid offset (>=0) to allow
1443         * the caller to do everything it want with the retval.
1444         */
1445        schedule();
1446        goto out;
1447    default:
1448        /*
1449         * Another bit of PARANOID. Note that the retval will be
1450         * 0 since no piece of kernel is supposed to do a check
1451         * for a negative retval of schedule_timeout() (since it
1452         * should never happens anyway). You just have the printk()
1453         * that will tell you if something is gone wrong and where.
1454         */
1455        if (timeout < 0) {
1456            printk(KERN_ERR "schedule_timeout: wrong timeout "
1457                "value %lx\n", timeout);
1458            dump_stack();
1459            current->state = TASK_RUNNING;
1460            goto out;
1461        }
1462    }
1463
1464    expire = timeout + jiffies;
1465
1466    setup_timer_on_stack(&timer, process_timeout, (unsigned long)current);
1467    __mod_timer(&timer, expire, false, TIMER_NOT_PINNED);
1468    schedule();
1469    del_singleshot_timer_sync(&timer);
1470
1471    /* Remove the timer from the object tracker */
1472    destroy_timer_on_stack(&timer);
1473
1474    timeout = expire - jiffies;
1475
1476 out:
1477    return timeout < 0 ? 0 : timeout;
1478}
1479EXPORT_SYMBOL(schedule_timeout);
1480
1481/*
1482 * We can use __set_current_state() here because schedule_timeout() calls
1483 * schedule() unconditionally.
1484 */
1485signed long __sched schedule_timeout_interruptible(signed long timeout)
1486{
1487    __set_current_state(TASK_INTERRUPTIBLE);
1488    return schedule_timeout(timeout);
1489}
1490EXPORT_SYMBOL(schedule_timeout_interruptible);
1491
1492signed long __sched schedule_timeout_killable(signed long timeout)
1493{
1494    __set_current_state(TASK_KILLABLE);
1495    return schedule_timeout(timeout);
1496}
1497EXPORT_SYMBOL(schedule_timeout_killable);
1498
1499signed long __sched schedule_timeout_uninterruptible(signed long timeout)
1500{
1501    __set_current_state(TASK_UNINTERRUPTIBLE);
1502    return schedule_timeout(timeout);
1503}
1504EXPORT_SYMBOL(schedule_timeout_uninterruptible);
1505
1506/* Thread ID - the internal kernel "pid" */
1507SYSCALL_DEFINE0(gettid)
1508{
1509    return task_pid_vnr(current);
1510}
1511
1512/**
1513 * do_sysinfo - fill in sysinfo struct
1514 * @info: pointer to buffer to fill
1515 */
1516int do_sysinfo(struct sysinfo *info)
1517{
1518    unsigned long mem_total, sav_total;
1519    unsigned int mem_unit, bitcount;
1520    struct timespec tp;
1521
1522    memset(info, 0, sizeof(struct sysinfo));
1523
1524    ktime_get_ts(&tp);
1525    monotonic_to_bootbased(&tp);
1526    info->uptime = tp.tv_sec + (tp.tv_nsec ? 1 : 0);
1527
1528    get_avenrun(info->loads, 0, SI_LOAD_SHIFT - FSHIFT);
1529
1530    info->procs = nr_threads;
1531
1532    si_meminfo(info);
1533    si_swapinfo(info);
1534
1535    /*
1536     * If the sum of all the available memory (i.e. ram + swap)
1537     * is less than can be stored in a 32 bit unsigned long then
1538     * we can be binary compatible with 2.2.x kernels. If not,
1539     * well, in that case 2.2.x was broken anyways...
1540     *
1541     * -Erik Andersen <andersee@debian.org>
1542     */
1543
1544    mem_total = info->totalram + info->totalswap;
1545    if (mem_total < info->totalram || mem_total < info->totalswap)
1546        goto out;
1547    bitcount = 0;
1548    mem_unit = info->mem_unit;
1549    while (mem_unit > 1) {
1550        bitcount++;
1551        mem_unit >>= 1;
1552        sav_total = mem_total;
1553        mem_total <<= 1;
1554        if (mem_total < sav_total)
1555            goto out;
1556    }
1557
1558    /*
1559     * If mem_total did not overflow, multiply all memory values by
1560     * info->mem_unit and set it to 1. This leaves things compatible
1561     * with 2.2.x, and also retains compatibility with earlier 2.4.x
1562     * kernels...
1563     */
1564
1565    info->mem_unit = 1;
1566    info->totalram <<= bitcount;
1567    info->freeram <<= bitcount;
1568    info->sharedram <<= bitcount;
1569    info->bufferram <<= bitcount;
1570    info->totalswap <<= bitcount;
1571    info->freeswap <<= bitcount;
1572    info->totalhigh <<= bitcount;
1573    info->freehigh <<= bitcount;
1574
1575out:
1576    return 0;
1577}
1578
1579SYSCALL_DEFINE1(sysinfo, struct sysinfo __user *, info)
1580{
1581    struct sysinfo val;
1582
1583    do_sysinfo(&val);
1584
1585    if (copy_to_user(info, &val, sizeof(struct sysinfo)))
1586        return -EFAULT;
1587
1588    return 0;
1589}
1590
1591static int __cpuinit init_timers_cpu(int cpu)
1592{
1593    int j;
1594    struct tvec_base *base;
1595    static char __cpuinitdata tvec_base_done[NR_CPUS];
1596
1597    if (!tvec_base_done[cpu]) {
1598        static char boot_done;
1599
1600        if (boot_done) {
1601            /*
1602             * The APs use this path later in boot
1603             */
1604            base = kmalloc_node(sizeof(*base),
1605                        GFP_KERNEL | __GFP_ZERO,
1606                        cpu_to_node(cpu));
1607            if (!base)
1608                return -ENOMEM;
1609
1610            /* Make sure that tvec_base is 2 byte aligned */
1611            if (tbase_get_deferrable(base)) {
1612                WARN_ON(1);
1613                kfree(base);
1614                return -ENOMEM;
1615            }
1616            per_cpu(tvec_bases, cpu) = base;
1617        } else {
1618            /*
1619             * This is for the boot CPU - we use compile-time
1620             * static initialisation because per-cpu memory isn't
1621             * ready yet and because the memory allocators are not
1622             * initialised either.
1623             */
1624            boot_done = 1;
1625            base = &boot_tvec_bases;
1626        }
1627        tvec_base_done[cpu] = 1;
1628    } else {
1629        base = per_cpu(tvec_bases, cpu);
1630    }
1631
1632    spin_lock_init(&base->lock);
1633
1634    for (j = 0; j < TVN_SIZE; j++) {
1635        INIT_LIST_HEAD(base->tv5.vec + j);
1636        INIT_LIST_HEAD(base->tv4.vec + j);
1637        INIT_LIST_HEAD(base->tv3.vec + j);
1638        INIT_LIST_HEAD(base->tv2.vec + j);
1639    }
1640    for (j = 0; j < TVR_SIZE; j++)
1641        INIT_LIST_HEAD(base->tv1.vec + j);
1642
1643    base->timer_jiffies = jiffies;
1644    base->next_timer = base->timer_jiffies;
1645    return 0;
1646}
1647
1648#ifdef CONFIG_HOTPLUG_CPU
1649static void migrate_timer_list(struct tvec_base *new_base, struct list_head *head)
1650{
1651    struct timer_list *timer;
1652
1653    while (!list_empty(head)) {
1654        timer = list_first_entry(head, struct timer_list, entry);
1655        detach_timer(timer, 0);
1656        timer_set_base(timer, new_base);
1657        if (time_before(timer->expires, new_base->next_timer) &&
1658            !tbase_get_deferrable(timer->base))
1659            new_base->next_timer = timer->expires;
1660        internal_add_timer(new_base, timer);
1661    }
1662}
1663
1664static void __cpuinit migrate_timers(int cpu)
1665{
1666    struct tvec_base *old_base;
1667    struct tvec_base *new_base;
1668    int i;
1669
1670    BUG_ON(cpu_online(cpu));
1671    old_base = per_cpu(tvec_bases, cpu);
1672    new_base = get_cpu_var(tvec_bases);
1673    /*
1674     * The caller is globally serialized and nobody else
1675     * takes two locks at once, deadlock is not possible.
1676     */
1677    spin_lock_irq(&new_base->lock);
1678    spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);
1679
1680    BUG_ON(old_base->running_timer);
1681
1682    for (i = 0; i < TVR_SIZE; i++)
1683        migrate_timer_list(new_base, old_base->tv1.vec + i);
1684    for (i = 0; i < TVN_SIZE; i++) {
1685        migrate_timer_list(new_base, old_base->tv2.vec + i);
1686        migrate_timer_list(new_base, old_base->tv3.vec + i);
1687        migrate_timer_list(new_base, old_base->tv4.vec + i);
1688        migrate_timer_list(new_base, old_base->tv5.vec + i);
1689    }
1690
1691    spin_unlock(&old_base->lock);
1692    spin_unlock_irq(&new_base->lock);
1693    put_cpu_var(tvec_bases);
1694}
1695#endif /* CONFIG_HOTPLUG_CPU */
1696
1697static int __cpuinit timer_cpu_notify(struct notifier_block *self,
1698                unsigned long action, void *hcpu)
1699{
1700    long cpu = (long)hcpu;
1701    int err;
1702
1703    switch(action) {
1704    case CPU_UP_PREPARE:
1705    case CPU_UP_PREPARE_FROZEN:
1706        err = init_timers_cpu(cpu);
1707        if (err < 0)
1708            return notifier_from_errno(err);
1709        break;
1710#ifdef CONFIG_HOTPLUG_CPU
1711    case CPU_DEAD:
1712    case CPU_DEAD_FROZEN:
1713        migrate_timers(cpu);
1714        break;
1715#endif
1716    default:
1717        break;
1718    }
1719    return NOTIFY_OK;
1720}
1721
1722static struct notifier_block __cpuinitdata timers_nb = {
1723    .notifier_call = timer_cpu_notify,
1724};
1725
1726
1727void __init init_timers(void)
1728{
1729    int err = timer_cpu_notify(&timers_nb, (unsigned long)CPU_UP_PREPARE,
1730                (void *)(long)smp_processor_id());
1731
1732    init_timer_stats();
1733
1734    BUG_ON(err != NOTIFY_OK);
1735    register_cpu_notifier(&timers_nb);
1736    open_softirq(TIMER_SOFTIRQ, run_timer_softirq);
1737}
1738
1739/**
1740 * msleep - sleep safely even with waitqueue interruptions
1741 * @msecs: Time in milliseconds to sleep for
1742 */
1743void msleep(unsigned int msecs)
1744{
1745    unsigned long timeout = msecs_to_jiffies(msecs) + 1;
1746
1747    while (timeout)
1748        timeout = schedule_timeout_uninterruptible(timeout);
1749}
1750
1751EXPORT_SYMBOL(msleep);
1752
1753/**
1754 * msleep_interruptible - sleep waiting for signals
1755 * @msecs: Time in milliseconds to sleep for
1756 */
1757unsigned long msleep_interruptible(unsigned int msecs)
1758{
1759    unsigned long timeout = msecs_to_jiffies(msecs) + 1;
1760
1761    while (timeout && !signal_pending(current))
1762        timeout = schedule_timeout_interruptible(timeout);
1763    return jiffies_to_msecs(timeout);
1764}
1765
1766EXPORT_SYMBOL(msleep_interruptible);
1767
1768static int __sched do_usleep_range(unsigned long min, unsigned long max)
1769{
1770    ktime_t kmin;
1771    unsigned long delta;
1772
1773    kmin = ktime_set(0, min * NSEC_PER_USEC);
1774    delta = (max - min) * NSEC_PER_USEC;
1775    return schedule_hrtimeout_range(&kmin, delta, HRTIMER_MODE_REL);
1776}
1777
1778/**
1779 * usleep_range - Drop in replacement for udelay where wakeup is flexible
1780 * @min: Minimum time in usecs to sleep
1781 * @max: Maximum time in usecs to sleep
1782 */
1783void usleep_range(unsigned long min, unsigned long max)
1784{
1785    __set_current_state(TASK_UNINTERRUPTIBLE);
1786    do_usleep_range(min, max);
1787}
1788EXPORT_SYMBOL(usleep_range);
1789

Archive Download this file



interactive