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

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