projects/linux·blob v2.6.12-rc5 · refs

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1/*
2 * linux/kernel/timer.c
3 *
4 * Kernel internal timers, kernel timekeeping, 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/notifier.h>
30#include <linux/thread_info.h>
31#include <linux/time.h>
32#include <linux/jiffies.h>
33#include <linux/posix-timers.h>
34#include <linux/cpu.h>
35#include <linux/syscalls.h>
36
37#include <asm/uaccess.h>
38#include <asm/unistd.h>
39#include <asm/div64.h>
40#include <asm/timex.h>
41#include <asm/io.h>
42
43#ifdef CONFIG_TIME_INTERPOLATION
44static void time_interpolator_update(long delta_nsec);
45#else
46#define time_interpolator_update(x)
47#endif
48
49/*
50 * per-CPU timer vector definitions:
51 */
52
53#define TVN_BITS (CONFIG_BASE_SMALL ? 4 : 6)
54#define TVR_BITS (CONFIG_BASE_SMALL ? 6 : 8)
55#define TVN_SIZE (1 << TVN_BITS)
56#define TVR_SIZE (1 << TVR_BITS)
57#define TVN_MASK (TVN_SIZE - 1)
58#define TVR_MASK (TVR_SIZE - 1)
59
60typedef struct tvec_s {
61 struct list_head vec[TVN_SIZE];
62} tvec_t;
63
64typedef struct tvec_root_s {
65 struct list_head vec[TVR_SIZE];
66} tvec_root_t;
67
68struct tvec_t_base_s {
69 spinlock_t lock;
70 unsigned long timer_jiffies;
71 struct timer_list *running_timer;
72 tvec_root_t tv1;
73 tvec_t tv2;
74 tvec_t tv3;
75 tvec_t tv4;
76 tvec_t tv5;
77} ____cacheline_aligned_in_smp;
78
79typedef struct tvec_t_base_s tvec_base_t;
80
81static inline void set_running_timer(tvec_base_t *base,
82 struct timer_list *timer)
83{
84#ifdef CONFIG_SMP
85 base->running_timer = timer;
86#endif
87}
88
89/* Fake initialization */
90static DEFINE_PER_CPU(tvec_base_t, tvec_bases) = { SPIN_LOCK_UNLOCKED };
91
92static void check_timer_failed(struct timer_list *timer)
93{
94 static int whine_count;
95 if (whine_count < 16) {
96 whine_count++;
97 printk("Uninitialised timer!\n");
98 printk("This is just a warning. Your computer is OK\n");
99 printk("function=0x%p, data=0x%lx\n",
100 timer->function, timer->data);
101 dump_stack();
102 }
103 /*
104 * Now fix it up
105 */
106 spin_lock_init(&timer->lock);
107 timer->magic = TIMER_MAGIC;
108}
109
110static inline void check_timer(struct timer_list *timer)
111{
112 if (timer->magic != TIMER_MAGIC)
113 check_timer_failed(timer);
114}
115
116
117static void internal_add_timer(tvec_base_t *base, struct timer_list *timer)
118{
119 unsigned long expires = timer->expires;
120 unsigned long idx = expires - base->timer_jiffies;
121 struct list_head *vec;
122
123 if (idx < TVR_SIZE) {
124 int i = expires & TVR_MASK;
125 vec = base->tv1.vec + i;
126 } else if (idx < 1 << (TVR_BITS + TVN_BITS)) {
127 int i = (expires >> TVR_BITS) & TVN_MASK;
128 vec = base->tv2.vec + i;
129 } else if (idx < 1 << (TVR_BITS + 2 * TVN_BITS)) {
130 int i = (expires >> (TVR_BITS + TVN_BITS)) & TVN_MASK;
131 vec = base->tv3.vec + i;
132 } else if (idx < 1 << (TVR_BITS + 3 * TVN_BITS)) {
133 int i = (expires >> (TVR_BITS + 2 * TVN_BITS)) & TVN_MASK;
134 vec = base->tv4.vec + i;
135 } else if ((signed long) idx < 0) {
136 /*
137 * Can happen if you add a timer with expires == jiffies,
138 * or you set a timer to go off in the past
139 */
140 vec = base->tv1.vec + (base->timer_jiffies & TVR_MASK);
141 } else {
142 int i;
143 /* If the timeout is larger than 0xffffffff on 64-bit
144 * architectures then we use the maximum timeout:
145 */
146 if (idx > 0xffffffffUL) {
147 idx = 0xffffffffUL;
148 expires = idx + base->timer_jiffies;
149 }
150 i = (expires >> (TVR_BITS + 3 * TVN_BITS)) & TVN_MASK;
151 vec = base->tv5.vec + i;
152 }
153 /*
154 * Timers are FIFO:
155 */
156 list_add_tail(&timer->entry, vec);
157}
158
159int __mod_timer(struct timer_list *timer, unsigned long expires)
160{
161 tvec_base_t *old_base, *new_base;
162 unsigned long flags;
163 int ret = 0;
164
165 BUG_ON(!timer->function);
166
167 check_timer(timer);
168
169 spin_lock_irqsave(&timer->lock, flags);
170 new_base = &__get_cpu_var(tvec_bases);
171repeat:
172 old_base = timer->base;
173
174 /*
175 * Prevent deadlocks via ordering by old_base < new_base.
176 */
177 if (old_base && (new_base != old_base)) {
178 if (old_base < new_base) {
179 spin_lock(&new_base->lock);
180 spin_lock(&old_base->lock);
181 } else {
182 spin_lock(&old_base->lock);
183 spin_lock(&new_base->lock);
184 }
185 /*
186 * The timer base might have been cancelled while we were
187 * trying to take the lock(s):
188 */
189 if (timer->base != old_base) {
190 spin_unlock(&new_base->lock);
191 spin_unlock(&old_base->lock);
192 goto repeat;
193 }
194 } else {
195 spin_lock(&new_base->lock);
196 if (timer->base != old_base) {
197 spin_unlock(&new_base->lock);
198 goto repeat;
199 }
200 }
201
202 /*
203 * Delete the previous timeout (if there was any), and install
204 * the new one:
205 */
206 if (old_base) {
207 list_del(&timer->entry);
208 ret = 1;
209 }
210 timer->expires = expires;
211 internal_add_timer(new_base, timer);
212 timer->base = new_base;
213
214 if (old_base && (new_base != old_base))
215 spin_unlock(&old_base->lock);
216 spin_unlock(&new_base->lock);
217 spin_unlock_irqrestore(&timer->lock, flags);
218
219 return ret;
220}
221
222EXPORT_SYMBOL(__mod_timer);
223
224/***
225 * add_timer_on - start a timer on a particular CPU
226 * @timer: the timer to be added
227 * @cpu: the CPU to start it on
228 *
229 * This is not very scalable on SMP. Double adds are not possible.
230 */
231void add_timer_on(struct timer_list *timer, int cpu)
232{
233 tvec_base_t *base = &per_cpu(tvec_bases, cpu);
234 unsigned long flags;
235
236 BUG_ON(timer_pending(timer) || !timer->function);
237
238 check_timer(timer);
239
240 spin_lock_irqsave(&base->lock, flags);
241 internal_add_timer(base, timer);
242 timer->base = base;
243 spin_unlock_irqrestore(&base->lock, flags);
244}
245
246
247/***
248 * mod_timer - modify a timer's timeout
249 * @timer: the timer to be modified
250 *
251 * mod_timer is a more efficient way to update the expire field of an
252 * active timer (if the timer is inactive it will be activated)
253 *
254 * mod_timer(timer, expires) is equivalent to:
255 *
256 * del_timer(timer); timer->expires = expires; add_timer(timer);
257 *
258 * Note that if there are multiple unserialized concurrent users of the
259 * same timer, then mod_timer() is the only safe way to modify the timeout,
260 * since add_timer() cannot modify an already running timer.
261 *
262 * The function returns whether it has modified a pending timer or not.
263 * (ie. mod_timer() of an inactive timer returns 0, mod_timer() of an
264 * active timer returns 1.)
265 */
266int mod_timer(struct timer_list *timer, unsigned long expires)
267{
268 BUG_ON(!timer->function);
269
270 check_timer(timer);
271
272 /*
273 * This is a common optimization triggered by the
274 * networking code - if the timer is re-modified
275 * to be the same thing then just return:
276 */
277 if (timer->expires == expires && timer_pending(timer))
278 return 1;
279
280 return __mod_timer(timer, expires);
281}
282
283EXPORT_SYMBOL(mod_timer);
284
285/***
286 * del_timer - deactive a timer.
287 * @timer: the timer to be deactivated
288 *
289 * del_timer() deactivates a timer - this works on both active and inactive
290 * timers.
291 *
292 * The function returns whether it has deactivated a pending timer or not.
293 * (ie. del_timer() of an inactive timer returns 0, del_timer() of an
294 * active timer returns 1.)
295 */
296int del_timer(struct timer_list *timer)
297{
298 unsigned long flags;
299 tvec_base_t *base;
300
301 check_timer(timer);
302
303repeat:
304 base = timer->base;
305 if (!base)
306 return 0;
307 spin_lock_irqsave(&base->lock, flags);
308 if (base != timer->base) {
309 spin_unlock_irqrestore(&base->lock, flags);
310 goto repeat;
311 }
312 list_del(&timer->entry);
313 /* Need to make sure that anybody who sees a NULL base also sees the list ops */
314 smp_wmb();
315 timer->base = NULL;
316 spin_unlock_irqrestore(&base->lock, flags);
317
318 return 1;
319}
320
321EXPORT_SYMBOL(del_timer);
322
323#ifdef CONFIG_SMP
324/***
325 * del_timer_sync - deactivate a timer and wait for the handler to finish.
326 * @timer: the timer to be deactivated
327 *
328 * This function only differs from del_timer() on SMP: besides deactivating
329 * the timer it also makes sure the handler has finished executing on other
330 * CPUs.
331 *
332 * Synchronization rules: callers must prevent restarting of the timer,
333 * otherwise this function is meaningless. It must not be called from
334 * interrupt contexts. The caller must not hold locks which would prevent
335 * completion of the timer's handler. Upon exit the timer is not queued and
336 * the handler is not running on any CPU.
337 *
338 * The function returns whether it has deactivated a pending timer or not.
339 *
340 * del_timer_sync() is slow and complicated because it copes with timer
341 * handlers which re-arm the timer (periodic timers). If the timer handler
342 * is known to not do this (a single shot timer) then use
343 * del_singleshot_timer_sync() instead.
344 */
345int del_timer_sync(struct timer_list *timer)
346{
347 tvec_base_t *base;
348 int i, ret = 0;
349
350 check_timer(timer);
351
352del_again:
353 ret += del_timer(timer);
354
355 for_each_online_cpu(i) {
356 base = &per_cpu(tvec_bases, i);
357 if (base->running_timer == timer) {
358 while (base->running_timer == timer) {
359 cpu_relax();
360 preempt_check_resched();
361 }
362 break;
363 }
364 }
365 smp_rmb();
366 if (timer_pending(timer))
367 goto del_again;
368
369 return ret;
370}
371EXPORT_SYMBOL(del_timer_sync);
372
373/***
374 * del_singleshot_timer_sync - deactivate a non-recursive timer
375 * @timer: the timer to be deactivated
376 *
377 * This function is an optimization of del_timer_sync for the case where the
378 * caller can guarantee the timer does not reschedule itself in its timer
379 * function.
380 *
381 * Synchronization rules: callers must prevent restarting of the timer,
382 * otherwise this function is meaningless. It must not be called from
383 * interrupt contexts. The caller must not hold locks which wold prevent
384 * completion of the timer's handler. Upon exit the timer is not queued and
385 * the handler is not running on any CPU.
386 *
387 * The function returns whether it has deactivated a pending timer or not.
388 */
389int del_singleshot_timer_sync(struct timer_list *timer)
390{
391 int ret = del_timer(timer);
392
393 if (!ret) {
394 ret = del_timer_sync(timer);
395 BUG_ON(ret);
396 }
397
398 return ret;
399}
400EXPORT_SYMBOL(del_singleshot_timer_sync);
401#endif
402
403static int cascade(tvec_base_t *base, tvec_t *tv, int index)
404{
405 /* cascade all the timers from tv up one level */
406 struct list_head *head, *curr;
407
408 head = tv->vec + index;
409 curr = head->next;
410 /*
411 * We are removing _all_ timers from the list, so we don't have to
412 * detach them individually, just clear the list afterwards.
413 */
414 while (curr != head) {
415 struct timer_list *tmp;
416
417 tmp = list_entry(curr, struct timer_list, entry);
418 BUG_ON(tmp->base != base);
419 curr = curr->next;
420 internal_add_timer(base, tmp);
421 }
422 INIT_LIST_HEAD(head);
423
424 return index;
425}
426
427/***
428 * __run_timers - run all expired timers (if any) on this CPU.
429 * @base: the timer vector to be processed.
430 *
431 * This function cascades all vectors and executes all expired timer
432 * vectors.
433 */
434#define INDEX(N) (base->timer_jiffies >> (TVR_BITS + N * TVN_BITS)) & TVN_MASK
435
436static inline void __run_timers(tvec_base_t *base)
437{
438 struct timer_list *timer;
439
440 spin_lock_irq(&base->lock);
441 while (time_after_eq(jiffies, base->timer_jiffies)) {
442 struct list_head work_list = LIST_HEAD_INIT(work_list);
443 struct list_head *head = &work_list;
444 int index = base->timer_jiffies & TVR_MASK;
445
446 /*
447 * Cascade timers:
448 */
449 if (!index &&
450 (!cascade(base, &base->tv2, INDEX(0))) &&
451 (!cascade(base, &base->tv3, INDEX(1))) &&
452 !cascade(base, &base->tv4, INDEX(2)))
453 cascade(base, &base->tv5, INDEX(3));
454 ++base->timer_jiffies;
455 list_splice_init(base->tv1.vec + index, &work_list);
456repeat:
457 if (!list_empty(head)) {
458 void (*fn)(unsigned long);
459 unsigned long data;
460
461 timer = list_entry(head->next,struct timer_list,entry);
462 fn = timer->function;
463 data = timer->data;
464
465 list_del(&timer->entry);
466 set_running_timer(base, timer);
467 smp_wmb();
468 timer->base = NULL;
469 spin_unlock_irq(&base->lock);
470 {
471 u32 preempt_count = preempt_count();
472 fn(data);
473 if (preempt_count != preempt_count()) {
474 printk("huh, entered %p with %08x, exited with %08x?\n", fn, preempt_count, preempt_count());
475 BUG();
476 }
477 }
478 spin_lock_irq(&base->lock);
479 goto repeat;
480 }
481 }
482 set_running_timer(base, NULL);
483 spin_unlock_irq(&base->lock);
484}
485
486#ifdef CONFIG_NO_IDLE_HZ
487/*
488 * Find out when the next timer event is due to happen. This
489 * is used on S/390 to stop all activity when a cpus is idle.
490 * This functions needs to be called disabled.
491 */
492unsigned long next_timer_interrupt(void)
493{
494 tvec_base_t *base;
495 struct list_head *list;
496 struct timer_list *nte;
497 unsigned long expires;
498 tvec_t *varray[4];
499 int i, j;
500
501 base = &__get_cpu_var(tvec_bases);
502 spin_lock(&base->lock);
503 expires = base->timer_jiffies + (LONG_MAX >> 1);
504 list = 0;
505
506 /* Look for timer events in tv1. */
507 j = base->timer_jiffies & TVR_MASK;
508 do {
509 list_for_each_entry(nte, base->tv1.vec + j, entry) {
510 expires = nte->expires;
511 if (j < (base->timer_jiffies & TVR_MASK))
512 list = base->tv2.vec + (INDEX(0));
513 goto found;
514 }
515 j = (j + 1) & TVR_MASK;
516 } while (j != (base->timer_jiffies & TVR_MASK));
517
518 /* Check tv2-tv5. */
519 varray[0] = &base->tv2;
520 varray[1] = &base->tv3;
521 varray[2] = &base->tv4;
522 varray[3] = &base->tv5;
523 for (i = 0; i < 4; i++) {
524 j = INDEX(i);
525 do {
526 if (list_empty(varray[i]->vec + j)) {
527 j = (j + 1) & TVN_MASK;
528 continue;
529 }
530 list_for_each_entry(nte, varray[i]->vec + j, entry)
531 if (time_before(nte->expires, expires))
532 expires = nte->expires;
533 if (j < (INDEX(i)) && i < 3)
534 list = varray[i + 1]->vec + (INDEX(i + 1));
535 goto found;
536 } while (j != (INDEX(i)));
537 }
538found:
539 if (list) {
540 /*
541 * The search wrapped. We need to look at the next list
542 * from next tv element that would cascade into tv element
543 * where we found the timer element.
544 */
545 list_for_each_entry(nte, list, entry) {
546 if (time_before(nte->expires, expires))
547 expires = nte->expires;
548 }
549 }
550 spin_unlock(&base->lock);
551 return expires;
552}
553#endif
554
555/******************************************************************/
556
557/*
558 * Timekeeping variables
559 */
560unsigned long tick_usec = TICK_USEC; /* USER_HZ period (usec) */
561unsigned long tick_nsec = TICK_NSEC; /* ACTHZ period (nsec) */
562
563/*
564 * The current time
565 * wall_to_monotonic is what we need to add to xtime (or xtime corrected
566 * for sub jiffie times) to get to monotonic time. Monotonic is pegged
567 * at zero at system boot time, so wall_to_monotonic will be negative,
568 * however, we will ALWAYS keep the tv_nsec part positive so we can use
569 * the usual normalization.
570 */
571struct timespec xtime __attribute__ ((aligned (16)));
572struct timespec wall_to_monotonic __attribute__ ((aligned (16)));
573
574EXPORT_SYMBOL(xtime);
575
576/* Don't completely fail for HZ > 500. */
577int tickadj = 500/HZ ? : 1; /* microsecs */
578
579
580/*
581 * phase-lock loop variables
582 */
583/* TIME_ERROR prevents overwriting the CMOS clock */
584int time_state = TIME_OK; /* clock synchronization status */
585int time_status = STA_UNSYNC; /* clock status bits */
586long time_offset; /* time adjustment (us) */
587long time_constant = 2; /* pll time constant */
588long time_tolerance = MAXFREQ; /* frequency tolerance (ppm) */
589long time_precision = 1; /* clock precision (us) */
590long time_maxerror = NTP_PHASE_LIMIT; /* maximum error (us) */
591long time_esterror = NTP_PHASE_LIMIT; /* estimated error (us) */
592static long time_phase; /* phase offset (scaled us) */
593long time_freq = (((NSEC_PER_SEC + HZ/2) % HZ - HZ/2) << SHIFT_USEC) / NSEC_PER_USEC;
594 /* frequency offset (scaled ppm)*/
595static long time_adj; /* tick adjust (scaled 1 / HZ) */
596long time_reftime; /* time at last adjustment (s) */
597long time_adjust;
598long time_next_adjust;
599
600/*
601 * this routine handles the overflow of the microsecond field
602 *
603 * The tricky bits of code to handle the accurate clock support
604 * were provided by Dave Mills ([email protected]) of NTP fame.
605 * They were originally developed for SUN and DEC kernels.
606 * All the kudos should go to Dave for this stuff.
607 *
608 */
609static void second_overflow(void)
610{
611 long ltemp;
612
613 /* Bump the maxerror field */
614 time_maxerror += time_tolerance >> SHIFT_USEC;
615 if ( time_maxerror > NTP_PHASE_LIMIT ) {
616 time_maxerror = NTP_PHASE_LIMIT;
617 time_status |= STA_UNSYNC;
618 }
619
620 /*
621 * Leap second processing. If in leap-insert state at
622 * the end of the day, the system clock is set back one
623 * second; if in leap-delete state, the system clock is
624 * set ahead one second. The microtime() routine or
625 * external clock driver will insure that reported time
626 * is always monotonic. The ugly divides should be
627 * replaced.
628 */
629 switch (time_state) {
630
631 case TIME_OK:
632 if (time_status & STA_INS)
633 time_state = TIME_INS;
634 else if (time_status & STA_DEL)
635 time_state = TIME_DEL;
636 break;
637
638 case TIME_INS:
639 if (xtime.tv_sec % 86400 == 0) {
640 xtime.tv_sec--;
641 wall_to_monotonic.tv_sec++;
642 /* The timer interpolator will make time change gradually instead
643 * of an immediate jump by one second.
644 */
645 time_interpolator_update(-NSEC_PER_SEC);
646 time_state = TIME_OOP;
647 clock_was_set();
648 printk(KERN_NOTICE "Clock: inserting leap second 23:59:60 UTC\n");
649 }
650 break;
651
652 case TIME_DEL:
653 if ((xtime.tv_sec + 1) % 86400 == 0) {
654 xtime.tv_sec++;
655 wall_to_monotonic.tv_sec--;
656 /* Use of time interpolator for a gradual change of time */
657 time_interpolator_update(NSEC_PER_SEC);
658 time_state = TIME_WAIT;
659 clock_was_set();
660 printk(KERN_NOTICE "Clock: deleting leap second 23:59:59 UTC\n");
661 }
662 break;
663
664 case TIME_OOP:
665 time_state = TIME_WAIT;
666 break;
667
668 case TIME_WAIT:
669 if (!(time_status & (STA_INS | STA_DEL)))
670 time_state = TIME_OK;
671 }
672
673 /*
674 * Compute the phase adjustment for the next second. In
675 * PLL mode, the offset is reduced by a fixed factor
676 * times the time constant. In FLL mode the offset is
677 * used directly. In either mode, the maximum phase
678 * adjustment for each second is clamped so as to spread
679 * the adjustment over not more than the number of
680 * seconds between updates.
681 */
682 if (time_offset < 0) {
683 ltemp = -time_offset;
684 if (!(time_status & STA_FLL))
685 ltemp >>= SHIFT_KG + time_constant;
686 if (ltemp > (MAXPHASE / MINSEC) << SHIFT_UPDATE)
687 ltemp = (MAXPHASE / MINSEC) << SHIFT_UPDATE;
688 time_offset += ltemp;
689 time_adj = -ltemp << (SHIFT_SCALE - SHIFT_HZ - SHIFT_UPDATE);
690 } else {
691 ltemp = time_offset;
692 if (!(time_status & STA_FLL))
693 ltemp >>= SHIFT_KG + time_constant;
694 if (ltemp > (MAXPHASE / MINSEC) << SHIFT_UPDATE)
695 ltemp = (MAXPHASE / MINSEC) << SHIFT_UPDATE;
696 time_offset -= ltemp;
697 time_adj = ltemp << (SHIFT_SCALE - SHIFT_HZ - SHIFT_UPDATE);
698 }
699
700 /*
701 * Compute the frequency estimate and additional phase
702 * adjustment due to frequency error for the next
703 * second. When the PPS signal is engaged, gnaw on the
704 * watchdog counter and update the frequency computed by
705 * the pll and the PPS signal.
706 */
707 pps_valid++;
708 if (pps_valid == PPS_VALID) { /* PPS signal lost */
709 pps_jitter = MAXTIME;
710 pps_stabil = MAXFREQ;
711 time_status &= ~(STA_PPSSIGNAL | STA_PPSJITTER |
712 STA_PPSWANDER | STA_PPSERROR);
713 }
714 ltemp = time_freq + pps_freq;
715 if (ltemp < 0)
716 time_adj -= -ltemp >>
717 (SHIFT_USEC + SHIFT_HZ - SHIFT_SCALE);
718 else
719 time_adj += ltemp >>
720 (SHIFT_USEC + SHIFT_HZ - SHIFT_SCALE);
721
722#if HZ == 100
723 /* Compensate for (HZ==100) != (1 << SHIFT_HZ).
724 * Add 25% and 3.125% to get 128.125; => only 0.125% error (p. 14)
725 */
726 if (time_adj < 0)
727 time_adj -= (-time_adj >> 2) + (-time_adj >> 5);
728 else
729 time_adj += (time_adj >> 2) + (time_adj >> 5);
730#endif
731#if HZ == 1000
732 /* Compensate for (HZ==1000) != (1 << SHIFT_HZ).
733 * Add 1.5625% and 0.78125% to get 1023.4375; => only 0.05% error (p. 14)
734 */
735 if (time_adj < 0)
736 time_adj -= (-time_adj >> 6) + (-time_adj >> 7);
737 else
738 time_adj += (time_adj >> 6) + (time_adj >> 7);
739#endif
740}
741
742/* in the NTP reference this is called "hardclock()" */
743static void update_wall_time_one_tick(void)
744{
745 long time_adjust_step, delta_nsec;
746
747 if ( (time_adjust_step = time_adjust) != 0 ) {
748 /* We are doing an adjtime thing.
749 *
750 * Prepare time_adjust_step to be within bounds.
751 * Note that a positive time_adjust means we want the clock
752 * to run faster.
753 *
754 * Limit the amount of the step to be in the range
755 * -tickadj .. +tickadj
756 */
757 if (time_adjust > tickadj)
758 time_adjust_step = tickadj;
759 else if (time_adjust < -tickadj)
760 time_adjust_step = -tickadj;
761
762 /* Reduce by this step the amount of time left */
763 time_adjust -= time_adjust_step;
764 }
765 delta_nsec = tick_nsec + time_adjust_step * 1000;
766 /*
767 * Advance the phase, once it gets to one microsecond, then
768 * advance the tick more.
769 */
770 time_phase += time_adj;
771 if (time_phase <= -FINENSEC) {
772 long ltemp = -time_phase >> (SHIFT_SCALE - 10);
773 time_phase += ltemp << (SHIFT_SCALE - 10);
774 delta_nsec -= ltemp;
775 }
776 else if (time_phase >= FINENSEC) {
777 long ltemp = time_phase >> (SHIFT_SCALE - 10);
778 time_phase -= ltemp << (SHIFT_SCALE - 10);
779 delta_nsec += ltemp;
780 }
781 xtime.tv_nsec += delta_nsec;
782 time_interpolator_update(delta_nsec);
783
784 /* Changes by adjtime() do not take effect till next tick. */
785 if (time_next_adjust != 0) {
786 time_adjust = time_next_adjust;
787 time_next_adjust = 0;
788 }
789}
790
791/*
792 * Using a loop looks inefficient, but "ticks" is
793 * usually just one (we shouldn't be losing ticks,
794 * we're doing this this way mainly for interrupt
795 * latency reasons, not because we think we'll
796 * have lots of lost timer ticks
797 */
798static void update_wall_time(unsigned long ticks)
799{
800 do {
801 ticks--;
802 update_wall_time_one_tick();
803 if (xtime.tv_nsec >= 1000000000) {
804 xtime.tv_nsec -= 1000000000;
805 xtime.tv_sec++;
806 second_overflow();
807 }
808 } while (ticks);
809}
810
811/*
812 * Called from the timer interrupt handler to charge one tick to the current
813 * process. user_tick is 1 if the tick is user time, 0 for system.
814 */
815void update_process_times(int user_tick)
816{
817 struct task_struct *p = current;
818 int cpu = smp_processor_id();
819
820 /* Note: this timer irq context must be accounted for as well. */
821 if (user_tick)
822 account_user_time(p, jiffies_to_cputime(1));
823 else
824 account_system_time(p, HARDIRQ_OFFSET, jiffies_to_cputime(1));
825 run_local_timers();
826 if (rcu_pending(cpu))
827 rcu_check_callbacks(cpu, user_tick);
828 scheduler_tick();
829 run_posix_cpu_timers(p);
830}
831
832/*
833 * Nr of active tasks - counted in fixed-point numbers
834 */
835static unsigned long count_active_tasks(void)
836{
837 return (nr_running() + nr_uninterruptible()) * FIXED_1;
838}
839
840/*
841 * Hmm.. Changed this, as the GNU make sources (load.c) seems to
842 * imply that avenrun[] is the standard name for this kind of thing.
843 * Nothing else seems to be standardized: the fractional size etc
844 * all seem to differ on different machines.
845 *
846 * Requires xtime_lock to access.
847 */
848unsigned long avenrun[3];
849
850EXPORT_SYMBOL(avenrun);
851
852/*
853 * calc_load - given tick count, update the avenrun load estimates.
854 * This is called while holding a write_lock on xtime_lock.
855 */
856static inline void calc_load(unsigned long ticks)
857{
858 unsigned long active_tasks; /* fixed-point */
859 static int count = LOAD_FREQ;
860
861 count -= ticks;
862 if (count < 0) {
863 count += LOAD_FREQ;
864 active_tasks = count_active_tasks();
865 CALC_LOAD(avenrun[0], EXP_1, active_tasks);
866 CALC_LOAD(avenrun[1], EXP_5, active_tasks);
867 CALC_LOAD(avenrun[2], EXP_15, active_tasks);
868 }
869}
870
871/* jiffies at the most recent update of wall time */
872unsigned long wall_jiffies = INITIAL_JIFFIES;
873
874/*
875 * This read-write spinlock protects us from races in SMP while
876 * playing with xtime and avenrun.
877 */
878#ifndef ARCH_HAVE_XTIME_LOCK
879seqlock_t xtime_lock __cacheline_aligned_in_smp = SEQLOCK_UNLOCKED;
880
881EXPORT_SYMBOL(xtime_lock);
882#endif
883
884/*
885 * This function runs timers and the timer-tq in bottom half context.
886 */
887static void run_timer_softirq(struct softirq_action *h)
888{
889 tvec_base_t *base = &__get_cpu_var(tvec_bases);
890
891 if (time_after_eq(jiffies, base->timer_jiffies))
892 __run_timers(base);
893}
894
895/*
896 * Called by the local, per-CPU timer interrupt on SMP.
897 */
898void run_local_timers(void)
899{
900 raise_softirq(TIMER_SOFTIRQ);
901}
902
903/*
904 * Called by the timer interrupt. xtime_lock must already be taken
905 * by the timer IRQ!
906 */
907static inline void update_times(void)
908{
909 unsigned long ticks;
910
911 ticks = jiffies - wall_jiffies;
912 if (ticks) {
913 wall_jiffies += ticks;
914 update_wall_time(ticks);
915 }
916 calc_load(ticks);
917}
918
919/*
920 * The 64-bit jiffies value is not atomic - you MUST NOT read it
921 * without sampling the sequence number in xtime_lock.
922 * jiffies is defined in the linker script...
923 */
924
925void do_timer(struct pt_regs *regs)
926{
927 jiffies_64++;
928 update_times();
929}
930
931#ifdef __ARCH_WANT_SYS_ALARM
932
933/*
934 * For backwards compatibility? This can be done in libc so Alpha
935 * and all newer ports shouldn't need it.
936 */
937asmlinkage unsigned long sys_alarm(unsigned int seconds)
938{
939 struct itimerval it_new, it_old;
940 unsigned int oldalarm;
941
942 it_new.it_interval.tv_sec = it_new.it_interval.tv_usec = 0;
943 it_new.it_value.tv_sec = seconds;
944 it_new.it_value.tv_usec = 0;
945 do_setitimer(ITIMER_REAL, &it_new, &it_old);
946 oldalarm = it_old.it_value.tv_sec;
947 /* ehhh.. We can't return 0 if we have an alarm pending.. */
948 /* And we'd better return too much than too little anyway */
949 if ((!oldalarm && it_old.it_value.tv_usec) || it_old.it_value.tv_usec >= 500000)
950 oldalarm++;
951 return oldalarm;
952}
953
954#endif
955
956#ifndef __alpha__
957
958/*
959 * The Alpha uses getxpid, getxuid, and getxgid instead. Maybe this
960 * should be moved into arch/i386 instead?
961 */
962
963/**
964 * sys_getpid - return the thread group id of the current process
965 *
966 * Note, despite the name, this returns the tgid not the pid. The tgid and
967 * the pid are identical unless CLONE_THREAD was specified on clone() in
968 * which case the tgid is the same in all threads of the same group.
969 *
970 * This is SMP safe as current->tgid does not change.
971 */
972asmlinkage long sys_getpid(void)
973{
974 return current->tgid;
975}
976
977/*
978 * Accessing ->group_leader->real_parent is not SMP-safe, it could
979 * change from under us. However, rather than getting any lock
980 * we can use an optimistic algorithm: get the parent
981 * pid, and go back and check that the parent is still
982 * the same. If it has changed (which is extremely unlikely
983 * indeed), we just try again..
984 *
985 * NOTE! This depends on the fact that even if we _do_
986 * get an old value of "parent", we can happily dereference
987 * the pointer (it was and remains a dereferencable kernel pointer
988 * no matter what): we just can't necessarily trust the result
989 * until we know that the parent pointer is valid.
990 *
991 * NOTE2: ->group_leader never changes from under us.
992 */
993asmlinkage long sys_getppid(void)
994{
995 int pid;
996 struct task_struct *me = current;
997 struct task_struct *parent;
998
999 parent = me->group_leader->real_parent;
1000 for (;;) {
1001 pid = parent->tgid;
1002#ifdef CONFIG_SMP
1003{
1004 struct task_struct *old = parent;
1005
1006 /*
1007 * Make sure we read the pid before re-reading the
1008 * parent pointer:
1009 */
1010 smp_rmb();
1011 parent = me->group_leader->real_parent;
1012 if (old != parent)
1013 continue;
1014}
1015#endif
1016 break;
1017 }
1018 return pid;
1019}
1020
1021asmlinkage long sys_getuid(void)
1022{
1023 /* Only we change this so SMP safe */
1024 return current->uid;
1025}
1026
1027asmlinkage long sys_geteuid(void)
1028{
1029 /* Only we change this so SMP safe */
1030 return current->euid;
1031}
1032
1033asmlinkage long sys_getgid(void)
1034{
1035 /* Only we change this so SMP safe */
1036 return current->gid;
1037}
1038
1039asmlinkage long sys_getegid(void)
1040{
1041 /* Only we change this so SMP safe */
1042 return current->egid;
1043}
1044
1045#endif
1046
1047static void process_timeout(unsigned long __data)
1048{
1049 wake_up_process((task_t *)__data);
1050}
1051
1052/**
1053 * schedule_timeout - sleep until timeout
1054 * @timeout: timeout value in jiffies
1055 *
1056 * Make the current task sleep until @timeout jiffies have
1057 * elapsed. The routine will return immediately unless
1058 * the current task state has been set (see set_current_state()).
1059 *
1060 * You can set the task state as follows -
1061 *
1062 * %TASK_UNINTERRUPTIBLE - at least @timeout jiffies are guaranteed to
1063 * pass before the routine returns. The routine will return 0
1064 *
1065 * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
1066 * delivered to the current task. In this case the remaining time
1067 * in jiffies will be returned, or 0 if the timer expired in time
1068 *
1069 * The current task state is guaranteed to be TASK_RUNNING when this
1070 * routine returns.
1071 *
1072 * Specifying a @timeout value of %MAX_SCHEDULE_TIMEOUT will schedule
1073 * the CPU away without a bound on the timeout. In this case the return
1074 * value will be %MAX_SCHEDULE_TIMEOUT.
1075 *
1076 * In all cases the return value is guaranteed to be non-negative.
1077 */
1078fastcall signed long __sched schedule_timeout(signed long timeout)
1079{
1080 struct timer_list timer;
1081 unsigned long expire;
1082
1083 switch (timeout)
1084 {
1085 case MAX_SCHEDULE_TIMEOUT:
1086 /*
1087 * These two special cases are useful to be comfortable
1088 * in the caller. Nothing more. We could take
1089 * MAX_SCHEDULE_TIMEOUT from one of the negative value
1090 * but I' d like to return a valid offset (>=0) to allow
1091 * the caller to do everything it want with the retval.
1092 */
1093 schedule();
1094 goto out;
1095 default:
1096 /*
1097 * Another bit of PARANOID. Note that the retval will be
1098 * 0 since no piece of kernel is supposed to do a check
1099 * for a negative retval of schedule_timeout() (since it
1100 * should never happens anyway). You just have the printk()
1101 * that will tell you if something is gone wrong and where.
1102 */
1103 if (timeout < 0)
1104 {
1105 printk(KERN_ERR "schedule_timeout: wrong timeout "
1106 "value %lx from %p\n", timeout,
1107 __builtin_return_address(0));
1108 current->state = TASK_RUNNING;
1109 goto out;
1110 }
1111 }
1112
1113 expire = timeout + jiffies;
1114
1115 init_timer(&timer);
1116 timer.expires = expire;
1117 timer.data = (unsigned long) current;
1118 timer.function = process_timeout;
1119
1120 add_timer(&timer);
1121 schedule();
1122 del_singleshot_timer_sync(&timer);
1123
1124 timeout = expire - jiffies;
1125
1126 out:
1127 return timeout < 0 ? 0 : timeout;
1128}
1129
1130EXPORT_SYMBOL(schedule_timeout);
1131
1132/* Thread ID - the internal kernel "pid" */
1133asmlinkage long sys_gettid(void)
1134{
1135 return current->pid;
1136}
1137
1138static long __sched nanosleep_restart(struct restart_block *restart)
1139{
1140 unsigned long expire = restart->arg0, now = jiffies;
1141 struct timespec __user *rmtp = (struct timespec __user *) restart->arg1;
1142 long ret;
1143
1144 /* Did it expire while we handled signals? */
1145 if (!time_after(expire, now))
1146 return 0;
1147
1148 current->state = TASK_INTERRUPTIBLE;
1149 expire = schedule_timeout(expire - now);
1150
1151 ret = 0;
1152 if (expire) {
1153 struct timespec t;
1154 jiffies_to_timespec(expire, &t);
1155
1156 ret = -ERESTART_RESTARTBLOCK;
1157 if (rmtp && copy_to_user(rmtp, &t, sizeof(t)))
1158 ret = -EFAULT;
1159 /* The 'restart' block is already filled in */
1160 }
1161 return ret;
1162}
1163
1164asmlinkage long sys_nanosleep(struct timespec __user *rqtp, struct timespec __user *rmtp)
1165{
1166 struct timespec t;
1167 unsigned long expire;
1168 long ret;
1169
1170 if (copy_from_user(&t, rqtp, sizeof(t)))
1171 return -EFAULT;
1172
1173 if ((t.tv_nsec >= 1000000000L) || (t.tv_nsec < 0) || (t.tv_sec < 0))
1174 return -EINVAL;
1175
1176 expire = timespec_to_jiffies(&t) + (t.tv_sec || t.tv_nsec);
1177 current->state = TASK_INTERRUPTIBLE;
1178 expire = schedule_timeout(expire);
1179
1180 ret = 0;
1181 if (expire) {
1182 struct restart_block *restart;
1183 jiffies_to_timespec(expire, &t);
1184 if (rmtp && copy_to_user(rmtp, &t, sizeof(t)))
1185 return -EFAULT;
1186
1187 restart = &current_thread_info()->restart_block;
1188 restart->fn = nanosleep_restart;
1189 restart->arg0 = jiffies + expire;
1190 restart->arg1 = (unsigned long) rmtp;
1191 ret = -ERESTART_RESTARTBLOCK;
1192 }
1193 return ret;
1194}
1195
1196/*
1197 * sys_sysinfo - fill in sysinfo struct
1198 */
1199asmlinkage long sys_sysinfo(struct sysinfo __user *info)
1200{
1201 struct sysinfo val;
1202 unsigned long mem_total, sav_total;
1203 unsigned int mem_unit, bitcount;
1204 unsigned long seq;
1205
1206 memset((char *)&val, 0, sizeof(struct sysinfo));
1207
1208 do {
1209 struct timespec tp;
1210 seq = read_seqbegin(&xtime_lock);
1211
1212 /*
1213 * This is annoying. The below is the same thing
1214 * posix_get_clock_monotonic() does, but it wants to
1215 * take the lock which we want to cover the loads stuff
1216 * too.
1217 */
1218
1219 getnstimeofday(&tp);
1220 tp.tv_sec += wall_to_monotonic.tv_sec;
1221 tp.tv_nsec += wall_to_monotonic.tv_nsec;
1222 if (tp.tv_nsec - NSEC_PER_SEC >= 0) {
1223 tp.tv_nsec = tp.tv_nsec - NSEC_PER_SEC;
1224 tp.tv_sec++;
1225 }
1226 val.uptime = tp.tv_sec + (tp.tv_nsec ? 1 : 0);
1227
1228 val.loads[0] = avenrun[0] << (SI_LOAD_SHIFT - FSHIFT);
1229 val.loads[1] = avenrun[1] << (SI_LOAD_SHIFT - FSHIFT);
1230 val.loads[2] = avenrun[2] << (SI_LOAD_SHIFT - FSHIFT);
1231
1232 val.procs = nr_threads;
1233 } while (read_seqretry(&xtime_lock, seq));
1234
1235 si_meminfo(&val);
1236 si_swapinfo(&val);
1237
1238 /*
1239 * If the sum of all the available memory (i.e. ram + swap)
1240 * is less than can be stored in a 32 bit unsigned long then
1241 * we can be binary compatible with 2.2.x kernels. If not,
1242 * well, in that case 2.2.x was broken anyways...
1243 *
1244 * -Erik Andersen <[email protected]>
1245 */
1246
1247 mem_total = val.totalram + val.totalswap;
1248 if (mem_total < val.totalram || mem_total < val.totalswap)
1249 goto out;
1250 bitcount = 0;
1251 mem_unit = val.mem_unit;
1252 while (mem_unit > 1) {
1253 bitcount++;
1254 mem_unit >>= 1;
1255 sav_total = mem_total;
1256 mem_total <<= 1;
1257 if (mem_total < sav_total)
1258 goto out;
1259 }
1260
1261 /*
1262 * If mem_total did not overflow, multiply all memory values by
1263 * val.mem_unit and set it to 1. This leaves things compatible
1264 * with 2.2.x, and also retains compatibility with earlier 2.4.x
1265 * kernels...
1266 */
1267
1268 val.mem_unit = 1;
1269 val.totalram <<= bitcount;
1270 val.freeram <<= bitcount;
1271 val.sharedram <<= bitcount;
1272 val.bufferram <<= bitcount;
1273 val.totalswap <<= bitcount;
1274 val.freeswap <<= bitcount;
1275 val.totalhigh <<= bitcount;
1276 val.freehigh <<= bitcount;
1277
1278 out:
1279 if (copy_to_user(info, &val, sizeof(struct sysinfo)))
1280 return -EFAULT;
1281
1282 return 0;
1283}
1284
1285static void __devinit init_timers_cpu(int cpu)
1286{
1287 int j;
1288 tvec_base_t *base;
1289
1290 base = &per_cpu(tvec_bases, cpu);
1291 spin_lock_init(&base->lock);
1292 for (j = 0; j < TVN_SIZE; j++) {
1293 INIT_LIST_HEAD(base->tv5.vec + j);
1294 INIT_LIST_HEAD(base->tv4.vec + j);
1295 INIT_LIST_HEAD(base->tv3.vec + j);
1296 INIT_LIST_HEAD(base->tv2.vec + j);
1297 }
1298 for (j = 0; j < TVR_SIZE; j++)
1299 INIT_LIST_HEAD(base->tv1.vec + j);
1300
1301 base->timer_jiffies = jiffies;
1302}
1303
1304#ifdef CONFIG_HOTPLUG_CPU
1305static int migrate_timer_list(tvec_base_t *new_base, struct list_head *head)
1306{
1307 struct timer_list *timer;
1308
1309 while (!list_empty(head)) {
1310 timer = list_entry(head->next, struct timer_list, entry);
1311 /* We're locking backwards from __mod_timer order here,
1312 beware deadlock. */
1313 if (!spin_trylock(&timer->lock))
1314 return 0;
1315 list_del(&timer->entry);
1316 internal_add_timer(new_base, timer);
1317 timer->base = new_base;
1318 spin_unlock(&timer->lock);
1319 }
1320 return 1;
1321}
1322
1323static void __devinit migrate_timers(int cpu)
1324{
1325 tvec_base_t *old_base;
1326 tvec_base_t *new_base;
1327 int i;
1328
1329 BUG_ON(cpu_online(cpu));
1330 old_base = &per_cpu(tvec_bases, cpu);
1331 new_base = &get_cpu_var(tvec_bases);
1332
1333 local_irq_disable();
1334again:
1335 /* Prevent deadlocks via ordering by old_base < new_base. */
1336 if (old_base < new_base) {
1337 spin_lock(&new_base->lock);
1338 spin_lock(&old_base->lock);
1339 } else {
1340 spin_lock(&old_base->lock);
1341 spin_lock(&new_base->lock);
1342 }
1343
1344 if (old_base->running_timer)
1345 BUG();
1346 for (i = 0; i < TVR_SIZE; i++)
1347 if (!migrate_timer_list(new_base, old_base->tv1.vec + i))
1348 goto unlock_again;
1349 for (i = 0; i < TVN_SIZE; i++)
1350 if (!migrate_timer_list(new_base, old_base->tv2.vec + i)
1351 || !migrate_timer_list(new_base, old_base->tv3.vec + i)
1352 || !migrate_timer_list(new_base, old_base->tv4.vec + i)
1353 || !migrate_timer_list(new_base, old_base->tv5.vec + i))
1354 goto unlock_again;
1355 spin_unlock(&old_base->lock);
1356 spin_unlock(&new_base->lock);
1357 local_irq_enable();
1358 put_cpu_var(tvec_bases);
1359 return;
1360
1361unlock_again:
1362 /* Avoid deadlock with __mod_timer, by backing off. */
1363 spin_unlock(&old_base->lock);
1364 spin_unlock(&new_base->lock);
1365 cpu_relax();
1366 goto again;
1367}
1368#endif /* CONFIG_HOTPLUG_CPU */
1369
1370static int __devinit timer_cpu_notify(struct notifier_block *self,
1371 unsigned long action, void *hcpu)
1372{
1373 long cpu = (long)hcpu;
1374 switch(action) {
1375 case CPU_UP_PREPARE:
1376 init_timers_cpu(cpu);
1377 break;
1378#ifdef CONFIG_HOTPLUG_CPU
1379 case CPU_DEAD:
1380 migrate_timers(cpu);
1381 break;
1382#endif
1383 default:
1384 break;
1385 }
1386 return NOTIFY_OK;
1387}
1388
1389static struct notifier_block __devinitdata timers_nb = {
1390 .notifier_call = timer_cpu_notify,
1391};
1392
1393
1394void __init init_timers(void)
1395{
1396 timer_cpu_notify(&timers_nb, (unsigned long)CPU_UP_PREPARE,
1397 (void *)(long)smp_processor_id());
1398 register_cpu_notifier(&timers_nb);
1399 open_softirq(TIMER_SOFTIRQ, run_timer_softirq, NULL);
1400}
1401
1402#ifdef CONFIG_TIME_INTERPOLATION
1403
1404struct time_interpolator *time_interpolator;
1405static struct time_interpolator *time_interpolator_list;
1406static DEFINE_SPINLOCK(time_interpolator_lock);
1407
1408static inline u64 time_interpolator_get_cycles(unsigned int src)
1409{
1410 unsigned long (*x)(void);
1411
1412 switch (src)
1413 {
1414 case TIME_SOURCE_FUNCTION:
1415 x = time_interpolator->addr;
1416 return x();
1417
1418 case TIME_SOURCE_MMIO64 :
1419 return readq((void __iomem *) time_interpolator->addr);
1420
1421 case TIME_SOURCE_MMIO32 :
1422 return readl((void __iomem *) time_interpolator->addr);
1423
1424 default: return get_cycles();
1425 }
1426}
1427
1428static inline u64 time_interpolator_get_counter(void)
1429{
1430 unsigned int src = time_interpolator->source;
1431
1432 if (time_interpolator->jitter)
1433 {
1434 u64 lcycle;
1435 u64 now;
1436
1437 do {
1438 lcycle = time_interpolator->last_cycle;
1439 now = time_interpolator_get_cycles(src);
1440 if (lcycle && time_after(lcycle, now))
1441 return lcycle;
1442 /* Keep track of the last timer value returned. The use of cmpxchg here
1443 * will cause contention in an SMP environment.
1444 */
1445 } while (unlikely(cmpxchg(&time_interpolator->last_cycle, lcycle, now) != lcycle));
1446 return now;
1447 }
1448 else
1449 return time_interpolator_get_cycles(src);
1450}
1451
1452void time_interpolator_reset(void)
1453{
1454 time_interpolator->offset = 0;
1455 time_interpolator->last_counter = time_interpolator_get_counter();
1456}
1457
1458#define GET_TI_NSECS(count,i) (((((count) - i->last_counter) & (i)->mask) * (i)->nsec_per_cyc) >> (i)->shift)
1459
1460unsigned long time_interpolator_get_offset(void)
1461{
1462 /* If we do not have a time interpolator set up then just return zero */
1463 if (!time_interpolator)
1464 return 0;
1465
1466 return time_interpolator->offset +
1467 GET_TI_NSECS(time_interpolator_get_counter(), time_interpolator);
1468}
1469
1470#define INTERPOLATOR_ADJUST 65536
1471#define INTERPOLATOR_MAX_SKIP 10*INTERPOLATOR_ADJUST
1472
1473static void time_interpolator_update(long delta_nsec)
1474{
1475 u64 counter;
1476 unsigned long offset;
1477
1478 /* If there is no time interpolator set up then do nothing */
1479 if (!time_interpolator)
1480 return;
1481
1482 /* The interpolator compensates for late ticks by accumulating
1483 * the late time in time_interpolator->offset. A tick earlier than
1484 * expected will lead to a reset of the offset and a corresponding
1485 * jump of the clock forward. Again this only works if the
1486 * interpolator clock is running slightly slower than the regular clock
1487 * and the tuning logic insures that.
1488 */
1489
1490 counter = time_interpolator_get_counter();
1491 offset = time_interpolator->offset + GET_TI_NSECS(counter, time_interpolator);
1492
1493 if (delta_nsec < 0 || (unsigned long) delta_nsec < offset)
1494 time_interpolator->offset = offset - delta_nsec;
1495 else {
1496 time_interpolator->skips++;
1497 time_interpolator->ns_skipped += delta_nsec - offset;
1498 time_interpolator->offset = 0;
1499 }
1500 time_interpolator->last_counter = counter;
1501
1502 /* Tuning logic for time interpolator invoked every minute or so.
1503 * Decrease interpolator clock speed if no skips occurred and an offset is carried.
1504 * Increase interpolator clock speed if we skip too much time.
1505 */
1506 if (jiffies % INTERPOLATOR_ADJUST == 0)
1507 {
1508 if (time_interpolator->skips == 0 && time_interpolator->offset > TICK_NSEC)
1509 time_interpolator->nsec_per_cyc--;
1510 if (time_interpolator->ns_skipped > INTERPOLATOR_MAX_SKIP && time_interpolator->offset == 0)
1511 time_interpolator->nsec_per_cyc++;
1512 time_interpolator->skips = 0;
1513 time_interpolator->ns_skipped = 0;
1514 }
1515}
1516
1517static inline int
1518is_better_time_interpolator(struct time_interpolator *new)
1519{
1520 if (!time_interpolator)
1521 return 1;
1522 return new->frequency > 2*time_interpolator->frequency ||
1523 (unsigned long)new->drift < (unsigned long)time_interpolator->drift;
1524}
1525
1526void
1527register_time_interpolator(struct time_interpolator *ti)
1528{
1529 unsigned long flags;
1530
1531 /* Sanity check */
1532 if (ti->frequency == 0 || ti->mask == 0)
1533 BUG();
1534
1535 ti->nsec_per_cyc = ((u64)NSEC_PER_SEC << ti->shift) / ti->frequency;
1536 spin_lock(&time_interpolator_lock);
1537 write_seqlock_irqsave(&xtime_lock, flags);
1538 if (is_better_time_interpolator(ti)) {
1539 time_interpolator = ti;
1540 time_interpolator_reset();
1541 }
1542 write_sequnlock_irqrestore(&xtime_lock, flags);
1543
1544 ti->next = time_interpolator_list;
1545 time_interpolator_list = ti;
1546 spin_unlock(&time_interpolator_lock);
1547}
1548
1549void
1550unregister_time_interpolator(struct time_interpolator *ti)
1551{
1552 struct time_interpolator *curr, **prev;
1553 unsigned long flags;
1554
1555 spin_lock(&time_interpolator_lock);
1556 prev = &time_interpolator_list;
1557 for (curr = *prev; curr; curr = curr->next) {
1558 if (curr == ti) {
1559 *prev = curr->next;
1560 break;
1561 }
1562 prev = &curr->next;
1563 }
1564
1565 write_seqlock_irqsave(&xtime_lock, flags);
1566 if (ti == time_interpolator) {
1567 /* we lost the best time-interpolator: */
1568 time_interpolator = NULL;
1569 /* find the next-best interpolator */
1570 for (curr = time_interpolator_list; curr; curr = curr->next)
1571 if (is_better_time_interpolator(curr))
1572 time_interpolator = curr;
1573 time_interpolator_reset();
1574 }
1575 write_sequnlock_irqrestore(&xtime_lock, flags);
1576 spin_unlock(&time_interpolator_lock);
1577}
1578#endif /* CONFIG_TIME_INTERPOLATION */
1579
1580/**
1581 * msleep - sleep safely even with waitqueue interruptions
1582 * @msecs: Time in milliseconds to sleep for
1583 */
1584void msleep(unsigned int msecs)
1585{
1586 unsigned long timeout = msecs_to_jiffies(msecs) + 1;
1587
1588 while (timeout) {
1589 set_current_state(TASK_UNINTERRUPTIBLE);
1590 timeout = schedule_timeout(timeout);
1591 }
1592}
1593
1594EXPORT_SYMBOL(msleep);
1595
1596/**
1597 * msleep_interruptible - sleep waiting for waitqueue interruptions
1598 * @msecs: Time in milliseconds to sleep for
1599 */
1600unsigned long msleep_interruptible(unsigned int msecs)
1601{
1602 unsigned long timeout = msecs_to_jiffies(msecs) + 1;
1603
1604 while (timeout && !signal_pending(current)) {
1605 set_current_state(TASK_INTERRUPTIBLE);
1606 timeout = schedule_timeout(timeout);
1607 }
1608 return jiffies_to_msecs(timeout);
1609}
1610
1611EXPORT_SYMBOL(msleep_interruptible);