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

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