/* * linux/kernel/timer.c * * Kernel internal timers, kernel timekeeping, basic process system calls * * Copyright (C) 1991, 1992 Linus Torvalds * * 1997-01-28 Modified by Finn Arne Gangstad to make timers scale better. * * 1997-09-10 Updated NTP code according to technical memorandum Jan '96 * "A Kernel Model for Precision Timekeeping" by Dave Mills * 1998-12-24 Fixed a xtime SMP race (we need the xtime_lock rw spinlock to * serialize accesses to xtime/lost_ticks). * Copyright (C) 1998 Andrea Arcangeli * 1999-03-10 Improved NTP compatibility by Ulrich Windl * 2002-05-31 Move sys_sysinfo here and make its locking sane, Robert Love * 2000-10-05 Implemented scalable SMP per-CPU timer handling. * Copyright (C) 2000, 2001, 2002 Ingo Molnar * Designed by David S. Miller, Alexey Kuznetsov and Ingo Molnar */ #include <linux/kernel_stat.h> #include <linux/module.h> #include <linux/interrupt.h> #include <linux/percpu.h> #include <linux/init.h> #include <linux/mm.h> #include <linux/swap.h> #include <linux/notifier.h> #include <linux/thread_info.h> #include <linux/time.h> #include <linux/jiffies.h> #include <linux/posix-timers.h> #include <linux/cpu.h> #include <linux/syscalls.h> #include <linux/delay.h> #include <asm/uaccess.h> #include <asm/unistd.h> #include <asm/div64.h> #include <asm/timex.h> #include <asm/io.h> u64 jiffies_64 __cacheline_aligned_in_smp = INITIAL_JIFFIES; EXPORT_SYMBOL(jiffies_64); /* * per-CPU timer vector definitions: */ #define TVN_BITS (CONFIG_BASE_SMALL ? 4 : 6) #define TVR_BITS (CONFIG_BASE_SMALL ? 6 : 8) #define TVN_SIZE (1 << TVN_BITS) #define TVR_SIZE (1 << TVR_BITS) #define TVN_MASK (TVN_SIZE - 1) #define TVR_MASK (TVR_SIZE - 1) typedef struct tvec_s { struct list_head vec[TVN_SIZE]; } tvec_t; typedef struct tvec_root_s { struct list_head vec[TVR_SIZE]; } tvec_root_t; struct tvec_t_base_s { spinlock_t lock; struct timer_list *running_timer; unsigned long timer_jiffies; tvec_root_t tv1; tvec_t tv2; tvec_t tv3; tvec_t tv4; tvec_t tv5; } ____cacheline_aligned_in_smp; typedef struct tvec_t_base_s tvec_base_t; tvec_base_t boot_tvec_bases; EXPORT_SYMBOL(boot_tvec_bases); static DEFINE_PER_CPU(tvec_base_t *, tvec_bases) = &boot_tvec_bases; /** * __round_jiffies - function to round jiffies to a full second * @j: the time in (absolute) jiffies that should be rounded * @cpu: the processor number on which the timeout will happen * * __round_jiffies rounds an absolute time in the future (in jiffies) * up or down to (approximately) full seconds. This is useful for timers * for which the exact time they fire does not matter too much, as long as * they fire approximately every X seconds. * * By rounding these timers to whole seconds, all such timers will fire * at the same time, rather than at various times spread out. The goal * of this is to have the CPU wake up less, which saves power. * * The exact rounding is skewed for each processor to avoid all * processors firing at the exact same time, which could lead * to lock contention or spurious cache line bouncing. * * The return value is the rounded version of the "j" parameter. */ unsigned long __round_jiffies(unsigned long j, int cpu) { int rem; unsigned long original = j; /* * We don't want all cpus firing their timers at once hitting the * same lock or cachelines, so we skew each extra cpu with an extra * 3 jiffies. This 3 jiffies came originally from the mm/ code which * already did this. * The skew is done by adding 3*cpunr, then round, then subtract this * extra offset again. */ j += cpu * 3; rem = j % HZ; /* * If the target jiffie is just after a whole second (which can happen * due to delays of the timer irq, long irq off times etc etc) then * we should round down to the whole second, not up. Use 1/4th second * as cutoff for this rounding as an extreme upper bound for this. */ if (rem < HZ/4) /* round down */ j = j - rem; else /* round up */ j = j - rem + HZ; /* now that we have rounded, subtract the extra skew again */ j -= cpu * 3; if (j <= jiffies) /* rounding ate our timeout entirely; */ return original; return j; } EXPORT_SYMBOL_GPL(__round_jiffies); /** * __round_jiffies_relative - function to round jiffies to a full second * @j: the time in (relative) jiffies that should be rounded * @cpu: the processor number on which the timeout will happen * * __round_jiffies_relative rounds a time delta in the future (in jiffies) * up or down to (approximately) full seconds. This is useful for timers * for which the exact time they fire does not matter too much, as long as * they fire approximately every X seconds. * * By rounding these timers to whole seconds, all such timers will fire * at the same time, rather than at various times spread out. The goal * of this is to have the CPU wake up less, which saves power. * * The exact rounding is skewed for each processor to avoid all * processors firing at the exact same time, which could lead * to lock contention or spurious cache line bouncing. * * The return value is the rounded version of the "j" parameter. */ unsigned long __round_jiffies_relative(unsigned long j, int cpu) { /* * In theory the following code can skip a jiffy in case jiffies * increments right between the addition and the later subtraction. * However since the entire point of this function is to use approximate * timeouts, it's entirely ok to not handle that. */ return __round_jiffies(j + jiffies, cpu) - jiffies; } EXPORT_SYMBOL_GPL(__round_jiffies_relative); /** * round_jiffies - function to round jiffies to a full second * @j: the time in (absolute) jiffies that should be rounded * * round_jiffies rounds an absolute time in the future (in jiffies) * up or down to (approximately) full seconds. This is useful for timers * for which the exact time they fire does not matter too much, as long as * they fire approximately every X seconds. * * By rounding these timers to whole seconds, all such timers will fire * at the same time, rather than at various times spread out. The goal * of this is to have the CPU wake up less, which saves power. * * The return value is the rounded version of the "j" parameter. */ unsigned long round_jiffies(unsigned long j) { return __round_jiffies(j, raw_smp_processor_id()); } EXPORT_SYMBOL_GPL(round_jiffies); /** * round_jiffies_relative - function to round jiffies to a full second * @j: the time in (relative) jiffies that should be rounded * * round_jiffies_relative rounds a time delta in the future (in jiffies) * up or down to (approximately) full seconds. This is useful for timers * for which the exact time they fire does not matter too much, as long as * they fire approximately every X seconds. * * By rounding these timers to whole seconds, all such timers will fire * at the same time, rather than at various times spread out. The goal * of this is to have the CPU wake up less, which saves power. * * The return value is the rounded version of the "j" parameter. */ unsigned long round_jiffies_relative(unsigned long j) { return __round_jiffies_relative(j, raw_smp_processor_id()); } EXPORT_SYMBOL_GPL(round_jiffies_relative); static inline void set_running_timer(tvec_base_t *base, struct timer_list *timer) { #ifdef CONFIG_SMP base->running_timer = timer; #endif } static void internal_add_timer(tvec_base_t *base, struct timer_list *timer) { unsigned long expires = timer->expires; unsigned long idx = expires - base->timer_jiffies; struct list_head *vec; if (idx < TVR_SIZE) { int i = expires & TVR_MASK; vec = base->tv1.vec + i; } else if (idx < 1 << (TVR_BITS + TVN_BITS)) { int i = (expires >> TVR_BITS) & TVN_MASK; vec = base->tv2.vec + i; } else if (idx < 1 << (TVR_BITS + 2 * TVN_BITS)) { int i = (expires >> (TVR_BITS + TVN_BITS)) & TVN_MASK; vec = base->tv3.vec + i; } else if (idx < 1 << (TVR_BITS + 3 * TVN_BITS)) { int i = (expires >> (TVR_BITS + 2 * TVN_BITS)) & TVN_MASK; vec = base->tv4.vec + i; } else if ((signed long) idx < 0) { /* * Can happen if you add a timer with expires == jiffies, * or you set a timer to go off in the past */ vec = base->tv1.vec + (base->timer_jiffies & TVR_MASK); } else { int i; /* If the timeout is larger than 0xffffffff on 64-bit * architectures then we use the maximum timeout: */ if (idx > 0xffffffffUL) { idx = 0xffffffffUL; expires = idx + base->timer_jiffies; } i = (expires >> (TVR_BITS + 3 * TVN_BITS)) & TVN_MASK; vec = base->tv5.vec + i; } /* * Timers are FIFO: */ list_add_tail(&timer->entry, vec); } /** * init_timer - initialize a timer. * @timer: the timer to be initialized * * init_timer() must be done to a timer prior calling *any* of the * other timer functions. */ void fastcall init_timer(struct timer_list *timer) { timer->entry.next = NULL; timer->base = __raw_get_cpu_var(tvec_bases); } EXPORT_SYMBOL(init_timer); static inline void detach_timer(struct timer_list *timer, int clear_pending) { struct list_head *entry = &timer->entry; __list_del(entry->prev, entry->next); if (clear_pending) entry->next = NULL; entry->prev = LIST_POISON2; } /* * We are using hashed locking: holding per_cpu(tvec_bases).lock * means that all timers which are tied to this base via timer->base are * locked, and the base itself is locked too. * * So __run_timers/migrate_timers can safely modify all timers which could * be found on ->tvX lists. * * When the timer's base is locked, and the timer removed from list, it is * possible to set timer->base = NULL and drop the lock: the timer remains * locked. */ static tvec_base_t *lock_timer_base(struct timer_list *timer, unsigned long *flags) __acquires(timer->base->lock) { tvec_base_t *base; for (;;) { base = timer->base; if (likely(base != NULL)) { spin_lock_irqsave(&base->lock, *flags); if (likely(base == timer->base)) return base; /* The timer has migrated to another CPU */ spin_unlock_irqrestore(&base->lock, *flags); } cpu_relax(); } } int __mod_timer(struct timer_list *timer, unsigned long expires) { tvec_base_t *base, *new_base; unsigned long flags; int ret = 0; BUG_ON(!timer->function); base = lock_timer_base(timer, &flags); if (timer_pending(timer)) { detach_timer(timer, 0); ret = 1; } new_base = __get_cpu_var(tvec_bases); if (base != new_base) { /* * We are trying to schedule the timer on the local CPU. * However we can't change timer's base while it is running, * otherwise del_timer_sync() can't detect that the timer's * handler yet has not finished. This also guarantees that * the timer is serialized wrt itself. */ if (likely(base->running_timer != timer)) { /* See the comment in lock_timer_base() */ timer->base = NULL; spin_unlock(&base->lock); base = new_base; spin_lock(&base->lock); timer->base = base; } } timer->expires = expires; internal_add_timer(base, timer); spin_unlock_irqrestore(&base->lock, flags); return ret; } EXPORT_SYMBOL(__mod_timer); /** * add_timer_on - start a timer on a particular CPU * @timer: the timer to be added * @cpu: the CPU to start it on * * This is not very scalable on SMP. Double adds are not possible. */ void add_timer_on(struct timer_list *timer, int cpu) { tvec_base_t *base = per_cpu(tvec_bases, cpu); unsigned long flags; BUG_ON(timer_pending(timer) || !timer->function); spin_lock_irqsave(&base->lock, flags); timer->base = base; internal_add_timer(base, timer); spin_unlock_irqrestore(&base->lock, flags); } /** * mod_timer - modify a timer's timeout * @timer: the timer to be modified * @expires: new timeout in jiffies * * mod_timer is a more efficient way to update the expire field of an * active timer (if the timer is inactive it will be activated) * * mod_timer(timer, expires) is equivalent to: * * del_timer(timer); timer->expires = expires; add_timer(timer); * * Note that if there are multiple unserialized concurrent users of the * same timer, then mod_timer() is the only safe way to modify the timeout, * since add_timer() cannot modify an already running timer. * * The function returns whether it has modified a pending timer or not. * (ie. mod_timer() of an inactive timer returns 0, mod_timer() of an * active timer returns 1.) */ int mod_timer(struct timer_list *timer, unsigned long expires) { BUG_ON(!timer->function); /* * This is a common optimization triggered by the * networking code - if the timer is re-modified * to be the same thing then just return: */ if (timer->expires == expires && timer_pending(timer)) return 1; return __mod_timer(timer, expires); } EXPORT_SYMBOL(mod_timer); /** * del_timer - deactive a timer. * @timer: the timer to be deactivated * * del_timer() deactivates a timer - this works on both active and inactive * timers. * * The function returns whether it has deactivated a pending timer or not. * (ie. del_timer() of an inactive timer returns 0, del_timer() of an * active timer returns 1.) */ int del_timer(struct timer_list *timer) { tvec_base_t *base; unsigned long flags; int ret = 0; if (timer_pending(timer)) { base = lock_timer_base(timer, &flags); if (timer_pending(timer)) { detach_timer(timer, 1); ret = 1; } spin_unlock_irqrestore(&base->lock, flags); } return ret; } EXPORT_SYMBOL(del_timer); #ifdef CONFIG_SMP /** * try_to_del_timer_sync - Try to deactivate a timer * @timer: timer do del * * This function tries to deactivate a timer. Upon successful (ret >= 0) * exit the timer is not queued and the handler is not running on any CPU. * * It must not be called from interrupt contexts. */ int try_to_del_timer_sync(struct timer_list *timer) { tvec_base_t *base; unsigned long flags; int ret = -1; base = lock_timer_base(timer, &flags); if (base->running_timer == timer) goto out; ret = 0; if (timer_pending(timer)) { detach_timer(timer, 1); ret = 1; } out: spin_unlock_irqrestore(&base->lock, flags); return ret; } /** * del_timer_sync - deactivate a timer and wait for the handler to finish. * @timer: the timer to be deactivated * * This function only differs from del_timer() on SMP: besides deactivating * the timer it also makes sure the handler has finished executing on other * CPUs. * * Synchronization rules: callers must prevent restarting of the timer, * otherwise this function is meaningless. It must not be called from * interrupt contexts. The caller must not hold locks which would prevent * completion of the timer's handler. The timer's handler must not call * add_timer_on(). Upon exit the timer is not queued and the handler is * not running on any CPU. * * The function returns whether it has deactivated a pending timer or not. */ int del_timer_sync(struct timer_list *timer) { for (;;) { int ret = try_to_del_timer_sync(timer); if (ret >= 0) return ret; cpu_relax(); } } EXPORT_SYMBOL(del_timer_sync); #endif static int cascade(tvec_base_t *base, tvec_t *tv, int index) { /* cascade all the timers from tv up one level */ struct timer_list *timer, *tmp; struct list_head tv_list; list_replace_init(tv->vec + index, &tv_list); /* * We are removing _all_ timers from the list, so we * don't have to detach them individually. */ list_for_each_entry_safe(timer, tmp, &tv_list, entry) { BUG_ON(timer->base != base); internal_add_timer(base, timer); } return index; } #define INDEX(N) ((base->timer_jiffies >> (TVR_BITS + (N) * TVN_BITS)) & TVN_MASK) /** * __run_timers - run all expired timers (if any) on this CPU. * @base: the timer vector to be processed. * * This function cascades all vectors and executes all expired timer * vectors. */ static inline void __run_timers(tvec_base_t *base) { struct timer_list *timer; spin_lock_irq(&base->lock); while (time_after_eq(jiffies, base->timer_jiffies)) { struct list_head work_list; struct list_head *head = &work_list; int index = base->timer_jiffies & TVR_MASK; /* * Cascade timers: */ if (!index && (!cascade(base, &base->tv2, INDEX(0))) && (!cascade(base, &base->tv3, INDEX(1))) && !cascade(base, &base->tv4, INDEX(2))) cascade(base, &base->tv5, INDEX(3)); ++base->timer_jiffies; list_replace_init(base->tv1.vec + index, &work_list); while (!list_empty(head)) { void (*fn)(unsigned long); unsigned long data; timer = list_entry(head->next,struct timer_list,entry); fn = timer->function; data = timer->data; set_running_timer(base, timer); detach_timer(timer, 1); spin_unlock_irq(&base->lock); { int preempt_count = preempt_count(); fn(data); if (preempt_count != preempt_count()) { printk(KERN_WARNING "huh, entered %p " "with preempt_count %08x, exited" " with %08x?\n", fn, preempt_count, preempt_count()); BUG(); } } spin_lock_irq(&base->lock); } } set_running_timer(base, NULL); spin_unlock_irq(&base->lock); } #ifdef CONFIG_NO_IDLE_HZ /* * Find out when the next timer event is due to happen. This * is used on S/390 to stop all activity when a cpus is idle. * This functions needs to be called disabled. */ unsigned long next_timer_interrupt(void) { tvec_base_t *base; struct list_head *list; struct timer_list *nte; unsigned long expires; unsigned long hr_expires = MAX_JIFFY_OFFSET; ktime_t hr_delta; tvec_t *varray[4]; int i, j; hr_delta = hrtimer_get_next_event(); if (hr_delta.tv64 != KTIME_MAX) { struct timespec tsdelta; tsdelta = ktime_to_timespec(hr_delta); hr_expires = timespec_to_jiffies(&tsdelta); if (hr_expires < 3) return hr_expires + jiffies; } hr_expires += jiffies; base = __get_cpu_var(tvec_bases); spin_lock(&base->lock); expires = base->timer_jiffies + (LONG_MAX >> 1); list = NULL; /* Look for timer events in tv1. */ j = base->timer_jiffies & TVR_MASK; do { list_for_each_entry(nte, base->tv1.vec + j, entry) { expires = nte->expires; if (j < (base->timer_jiffies & TVR_MASK)) list = base->tv2.vec + (INDEX(0)); goto found; } j = (j + 1) & TVR_MASK; } while (j != (base->timer_jiffies & TVR_MASK)); /* Check tv2-tv5. */ varray[0] = &base->tv2; varray[1] = &base->tv3; varray[2] = &base->tv4; varray[3] = &base->tv5; for (i = 0; i < 4; i++) { j = INDEX(i); do { if (list_empty(varray[i]->vec + j)) { j = (j + 1) & TVN_MASK; continue; } list_for_each_entry(nte, varray[i]->vec + j, entry) if (time_before(nte->expires, expires)) expires = nte->expires; if (j < (INDEX(i)) && i < 3) list = varray[i + 1]->vec + (INDEX(i + 1)); goto found; } while (j != (INDEX(i))); } found: if (list) { /* * The search wrapped. We need to look at the next list * from next tv element that would cascade into tv element * where we found the timer element. */ list_for_each_entry(nte, list, entry) { if (time_before(nte->expires, expires)) expires = nte->expires; } } spin_unlock(&base->lock); /* * It can happen that other CPUs service timer IRQs and increment * jiffies, but we have not yet got a local timer tick to process * the timer wheels. In that case, the expiry time can be before * jiffies, but since the high-resolution timer here is relative to * jiffies, the default expression when high-resolution timers are * not active, * * time_before(MAX_JIFFY_OFFSET + jiffies, expires) * * would falsely evaluate to true. If that is the case, just * return jiffies so that we can immediately fire the local timer */ if (time_before(expires, jiffies)) return jiffies; if (time_before(hr_expires, expires)) return hr_expires; return expires; } #endif /******************************************************************/ /* * The current time * wall_to_monotonic is what we need to add to xtime (or xtime corrected * for sub jiffie times) to get to monotonic time. Monotonic is pegged * at zero at system boot time, so wall_to_monotonic will be negative, * however, we will ALWAYS keep the tv_nsec part positive so we can use * the usual normalization. */ struct timespec xtime __attribute__ ((aligned (16))); struct timespec wall_to_monotonic __attribute__ ((aligned (16))); EXPORT_SYMBOL(xtime); /* XXX - all of this timekeeping code should be later moved to time.c */ #include <linux/clocksource.h> static struct clocksource *clock; /* pointer to current clocksource */ #ifdef CONFIG_GENERIC_TIME /** * __get_nsec_offset - Returns nanoseconds since last call to periodic_hook * * private function, must hold xtime_lock lock when being * called. Returns the number of nanoseconds since the * last call to update_wall_time() (adjusted by NTP scaling) */ static inline s64 __get_nsec_offset(void) { cycle_t cycle_now, cycle_delta; s64 ns_offset; /* read clocksource: */ cycle_now = clocksource_read(clock); /* calculate the delta since the last update_wall_time: */ cycle_delta = (cycle_now - clock->cycle_last) & clock->mask; /* convert to nanoseconds: */ ns_offset = cyc2ns(clock, cycle_delta); return ns_offset; } /** * __get_realtime_clock_ts - Returns the time of day in a timespec * @ts: pointer to the timespec to be set * * Returns the time of day in a timespec. Used by * do_gettimeofday() and get_realtime_clock_ts(). */ static inline void __get_realtime_clock_ts(struct timespec *ts) { unsigned long seq; s64 nsecs; do { seq = read_seqbegin(&xtime_lock); *ts = xtime; nsecs = __get_nsec_offset(); } while (read_seqretry(&xtime_lock, seq)); timespec_add_ns(ts, nsecs); } /** * getnstimeofday - Returns the time of day in a timespec * @ts: pointer to the timespec to be set * * Returns the time of day in a timespec. */ void getnstimeofday(struct timespec *ts) { __get_realtime_clock_ts(ts); } EXPORT_SYMBOL(getnstimeofday); /** * do_gettimeofday - Returns the time of day in a timeval * @tv: pointer to the timeval to be set * * NOTE: Users should be converted to using get_realtime_clock_ts() */ void do_gettimeofday(struct timeval *tv) { struct timespec now; __get_realtime_clock_ts(&now); tv->tv_sec = now.tv_sec; tv->tv_usec = now.tv_nsec/1000; } EXPORT_SYMBOL(do_gettimeofday); /** * do_settimeofday - Sets the time of day * @tv: pointer to the timespec variable containing the new time * * Sets the time of day to the new time and update NTP and notify hrtimers */ int do_settimeofday(struct timespec *tv) { unsigned long flags; time_t wtm_sec, sec = tv->tv_sec; long wtm_nsec, nsec = tv->tv_nsec; if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC) return -EINVAL; write_seqlock_irqsave(&xtime_lock, flags); nsec -= __get_nsec_offset(); wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec); wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec); set_normalized_timespec(&xtime, sec, nsec); set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec); clock->error = 0; ntp_clear(); write_sequnlock_irqrestore(&xtime_lock, flags); /* signal hrtimers about time change */ clock_was_set(); return 0; } EXPORT_SYMBOL(do_settimeofday); /** * change_clocksource - Swaps clocksources if a new one is available * * Accumulates current time interval and initializes new clocksource */ static int change_clocksource(void) { struct clocksource *new; cycle_t now; u64 nsec; new = clocksource_get_next(); if (clock != new) { now = clocksource_read(new); nsec = __get_nsec_offset(); timespec_add_ns(&xtime, nsec); clock = new; clock->cycle_last = now; printk(KERN_INFO "Time: %s clocksource has been installed.\n", clock->name); return 1; } else if (clock->update_callback) { return clock->update_callback(); } return 0; } #else static inline int change_clocksource(void) { return 0; } #endif /** * timeofday_is_continuous - check to see if timekeeping is free running */ int timekeeping_is_continuous(void) { unsigned long seq; int ret; do { seq = read_seqbegin(&xtime_lock); ret = clock->is_continuous; } while (read_seqretry(&xtime_lock, seq)); return ret; } /* * timekeeping_init - Initializes the clocksource and common timekeeping values */ void __init timekeeping_init(void) { unsigned long flags; write_seqlock_irqsave(&xtime_lock, flags); ntp_clear(); clock = clocksource_get_next(); clocksource_calculate_interval(clock, tick_nsec); clock->cycle_last = clocksource_read(clock); write_sequnlock_irqrestore(&xtime_lock, flags); } static int timekeeping_suspended; /** * timekeeping_resume - Resumes the generic timekeeping subsystem. * @dev: unused * * This is for the generic clocksource timekeeping. * xtime/wall_to_monotonic/jiffies/etc are * still managed by arch specific suspend/resume code. */ static int timekeeping_resume(struct sys_device *dev) { unsigned long flags; write_seqlock_irqsave(&xtime_lock, flags); /* restart the last cycle value */ clock->cycle_last = clocksource_read(clock); clock->error = 0; timekeeping_suspended = 0; write_sequnlock_irqrestore(&xtime_lock, flags); return 0; } static int timekeeping_suspend(struct sys_device *dev, pm_message_t state) { unsigned long flags; write_seqlock_irqsave(&xtime_lock, flags); timekeeping_suspended = 1; write_sequnlock_irqrestore(&xtime_lock, flags); return 0; } /* sysfs resume/suspend bits for timekeeping */ static struct sysdev_class timekeeping_sysclass = { .resume = timekeeping_resume, .suspend = timekeeping_suspend, set_kset_name("timekeeping"), }; static struct sys_device device_timer = { .id = 0, .cls = &timekeeping_sysclass, }; static int __init timekeeping_init_device(void) { int error = sysdev_class_register(&timekeeping_sysclass); if (!error) error = sysdev_register(&device_timer); return error; } device_initcall(timekeeping_init_device); /* * If the error is already larger, we look ahead even further * to compensate for late or lost adjustments. */ static __always_inline int clocksource_bigadjust(s64 error, s64 *interval, s64 *offset) { s64 tick_error, i; u32 look_ahead, adj; s32 error2, mult; /* * Use the current error value to determine how much to look ahead. * The larger the error the slower we adjust for it to avoid problems * with losing too many ticks, otherwise we would overadjust and * produce an even larger error. The smaller the adjustment the * faster we try to adjust for it, as lost ticks can do less harm * here. This is tuned so that an error of about 1 msec is adusted * within about 1 sec (or 2^20 nsec in 2^SHIFT_HZ ticks). */ error2 = clock->error >> (TICK_LENGTH_SHIFT + 22 - 2 * SHIFT_HZ); error2 = abs(error2); for (look_ahead = 0; error2 > 0; look_ahead++) error2 >>= 2; /* * Now calculate the error in (1 << look_ahead) ticks, but first * remove the single look ahead already included in the error. */ tick_error = current_tick_length() >> (TICK_LENGTH_SHIFT - clock->shift + 1); tick_error -= clock->xtime_interval >> 1; error = ((error - tick_error) >> look_ahead) + tick_error; /* Finally calculate the adjustment shift value. */ i = *interval; mult = 1; if (error < 0) { error = -error; *interval = -*interval; *offset = -*offset; mult = -1; } for (adj = 0; error > i; adj++) error >>= 1; *interval <<= adj; *offset <<= adj; return mult << adj; } /* * Adjust the multiplier to reduce the error value, * this is optimized for the most common adjustments of -1,0,1, * for other values we can do a bit more work. */ static void clocksource_adjust(struct clocksource *clock, s64 offset) { s64 error, interval = clock->cycle_interval; int adj; error = clock->error >> (TICK_LENGTH_SHIFT - clock->shift - 1); if (error > interval) { error >>= 2; if (likely(error <= interval)) adj = 1; else adj = clocksource_bigadjust(error, &interval, &offset); } else if (error < -interval) { error >>= 2; if (likely(error >= -interval)) { adj = -1; interval = -interval; offset = -offset; } else adj = clocksource_bigadjust(error, &interval, &offset); } else return; clock->mult += adj; clock->xtime_interval += interval; clock->xtime_nsec -= offset; clock->error -= (interval - offset) << (TICK_LENGTH_SHIFT - clock->shift); } /** * update_wall_time - Uses the current clocksource to increment the wall time * * Called from the timer interrupt, must hold a write on xtime_lock. */ static void update_wall_time(void) { cycle_t offset; /* Make sure we're fully resumed: */ if (unlikely(timekeeping_suspended)) return; #ifdef CONFIG_GENERIC_TIME offset = (clocksource_read(clock) - clock->cycle_last) & clock->mask; #else offset = clock->cycle_interval; #endif clock->xtime_nsec += (s64)xtime.tv_nsec << clock->shift; /* normally this loop will run just once, however in the * case of lost or late ticks, it will accumulate correctly. */ while (offset >= clock->cycle_interval) { /* accumulate one interval */ clock->xtime_nsec += clock->xtime_interval; clock->cycle_last += clock->cycle_interval; offset -= clock->cycle_interval; if (clock->xtime_nsec >= (u64)NSEC_PER_SEC << clock->shift) { clock->xtime_nsec -= (u64)NSEC_PER_SEC << clock->shift; xtime.tv_sec++; second_overflow(); } /* interpolator bits */ time_interpolator_update(clock->xtime_interval >> clock->shift); /* accumulate error between NTP and clock interval */ clock->error += current_tick_length(); clock->error -= clock->xtime_interval << (TICK_LENGTH_SHIFT - clock->shift); } /* correct the clock when NTP error is too big */ clocksource_adjust(clock, offset); /* store full nanoseconds into xtime */ xtime.tv_nsec = (s64)clock->xtime_nsec >> clock->shift; clock->xtime_nsec -= (s64)xtime.tv_nsec << clock->shift; /* check to see if there is a new clocksource to use */ if (change_clocksource()) { clock->error = 0; clock->xtime_nsec = 0; clocksource_calculate_interval(clock, tick_nsec); } } /* * Called from the timer interrupt handler to charge one tick to the current * process. user_tick is 1 if the tick is user time, 0 for system. */ void update_process_times(int user_tick) { struct task_struct *p = current; int cpu = smp_processor_id(); /* Note: this timer irq context must be accounted for as well. */ if (user_tick) account_user_time(p, jiffies_to_cputime(1)); else account_system_time(p, HARDIRQ_OFFSET, jiffies_to_cputime(1)); run_local_timers(); if (rcu_pending(cpu)) rcu_check_callbacks(cpu, user_tick); scheduler_tick(); run_posix_cpu_timers(p); } /* * Nr of active tasks - counted in fixed-point numbers */ static unsigned long count_active_tasks(void) { return nr_active() * FIXED_1; } /* * Hmm.. Changed this, as the GNU make sources (load.c) seems to * imply that avenrun[] is the standard name for this kind of thing. * Nothing else seems to be standardized: the fractional size etc * all seem to differ on different machines. * * Requires xtime_lock to access. */ unsigned long avenrun[3]; EXPORT_SYMBOL(avenrun); /* * calc_load - given tick count, update the avenrun load estimates. * This is called while holding a write_lock on xtime_lock. */ static inline void calc_load(unsigned long ticks) { unsigned long active_tasks; /* fixed-point */ static int count = LOAD_FREQ; active_tasks = count_active_tasks(); for (count -= ticks; count < 0; count += LOAD_FREQ) { CALC_LOAD(avenrun[0], EXP_1, active_tasks); CALC_LOAD(avenrun[1], EXP_5, active_tasks); CALC_LOAD(avenrun[2], EXP_15, active_tasks); } } /* * This read-write spinlock protects us from races in SMP while * playing with xtime and avenrun. */ #ifndef ARCH_HAVE_XTIME_LOCK __cacheline_aligned_in_smp DEFINE_SEQLOCK(xtime_lock); EXPORT_SYMBOL(xtime_lock); #endif /* * This function runs timers and the timer-tq in bottom half context. */ static void run_timer_softirq(struct softirq_action *h) { tvec_base_t *base = __get_cpu_var(tvec_bases); hrtimer_run_queues(); if (time_after_eq(jiffies, base->timer_jiffies)) __run_timers(base); } /* * Called by the local, per-CPU timer interrupt on SMP. */ void run_local_timers(void) { raise_softirq(TIMER_SOFTIRQ); softlockup_tick(); } /* * Called by the timer interrupt. xtime_lock must already be taken * by the timer IRQ! */ static inline void update_times(unsigned long ticks) { update_wall_time(); calc_load(ticks); } /* * The 64-bit jiffies value is not atomic - you MUST NOT read it * without sampling the sequence number in xtime_lock. * jiffies is defined in the linker script... */ void do_timer(unsigned long ticks) { jiffies_64 += ticks; update_times(ticks); } #ifdef __ARCH_WANT_SYS_ALARM /* * For backwards compatibility? This can be done in libc so Alpha * and all newer ports shouldn't need it. */ asmlinkage unsigned long sys_alarm(unsigned int seconds) { return alarm_setitimer(seconds); } #endif #ifndef __alpha__ /* * The Alpha uses getxpid, getxuid, and getxgid instead. Maybe this * should be moved into arch/i386 instead? */ /** * sys_getpid - return the thread group id of the current process * * Note, despite the name, this returns the tgid not the pid. The tgid and * the pid are identical unless CLONE_THREAD was specified on clone() in * which case the tgid is the same in all threads of the same group. * * This is SMP safe as current->tgid does not change. */ asmlinkage long sys_getpid(void) { return current->tgid; } /* * Accessing ->real_parent is not SMP-safe, it could * change from under us. However, we can use a stale * value of ->real_parent under rcu_read_lock(), see * release_task()->call_rcu(delayed_put_task_struct). */ asmlinkage long sys_getppid(void) { int pid; rcu_read_lock(); pid = rcu_dereference(current->real_parent)->tgid; rcu_read_unlock(); return pid; } asmlinkage long sys_getuid(void) { /* Only we change this so SMP safe */ return current->uid; } asmlinkage long sys_geteuid(void) { /* Only we change this so SMP safe */ return current->euid; } asmlinkage long sys_getgid(void) { /* Only we change this so SMP safe */ return current->gid; } asmlinkage long sys_getegid(void) { /* Only we change this so SMP safe */ return current->egid; } #endif static void process_timeout(unsigned long __data) { wake_up_process((struct task_struct *)__data); } /** * schedule_timeout - sleep until timeout * @timeout: timeout value in jiffies * * Make the current task sleep until @timeout jiffies have * elapsed. The routine will return immediately unless * the current task state has been set (see set_current_state()). * * You can set the task state as follows - * * %TASK_UNINTERRUPTIBLE - at least @timeout jiffies are guaranteed to * pass before the routine returns. The routine will return 0 * * %TASK_INTERRUPTIBLE - the routine may return early if a signal is * delivered to the current task. In this case the remaining time * in jiffies will be returned, or 0 if the timer expired in time * * The current task state is guaranteed to be TASK_RUNNING when this * routine returns. * * Specifying a @timeout value of %MAX_SCHEDULE_TIMEOUT will schedule * the CPU away without a bound on the timeout. In this case the return * value will be %MAX_SCHEDULE_TIMEOUT. * * In all cases the return value is guaranteed to be non-negative. */ fastcall signed long __sched schedule_timeout(signed long timeout) { struct timer_list timer; unsigned long expire; switch (timeout) { case MAX_SCHEDULE_TIMEOUT: /* * These two special cases are useful to be comfortable * in the caller. Nothing more. We could take * MAX_SCHEDULE_TIMEOUT from one of the negative value * but I' d like to return a valid offset (>=0) to allow * the caller to do everything it want with the retval. */ schedule(); goto out; default: /* * Another bit of PARANOID. Note that the retval will be * 0 since no piece of kernel is supposed to do a check * for a negative retval of schedule_timeout() (since it * should never happens anyway). You just have the printk() * that will tell you if something is gone wrong and where. */ if (timeout < 0) { printk(KERN_ERR "schedule_timeout: wrong timeout " "value %lx from %p\n", timeout, __builtin_return_address(0)); current->state = TASK_RUNNING; goto out; } } expire = timeout + jiffies; setup_timer(&timer, process_timeout, (unsigned long)current); __mod_timer(&timer, expire); schedule(); del_singleshot_timer_sync(&timer); timeout = expire - jiffies; out: return timeout < 0 ? 0 : timeout; } EXPORT_SYMBOL(schedule_timeout); /* * We can use __set_current_state() here because schedule_timeout() calls * schedule() unconditionally. */ signed long __sched schedule_timeout_interruptible(signed long timeout) { __set_current_state(TASK_INTERRUPTIBLE); return schedule_timeout(timeout); } EXPORT_SYMBOL(schedule_timeout_interruptible); signed long __sched schedule_timeout_uninterruptible(signed long timeout) { __set_current_state(TASK_UNINTERRUPTIBLE); return schedule_timeout(timeout); } EXPORT_SYMBOL(schedule_timeout_uninterruptible); /* Thread ID - the internal kernel "pid" */ asmlinkage long sys_gettid(void) { return current->pid; } /** * sys_sysinfo - fill in sysinfo struct * @info: pointer to buffer to fill */ asmlinkage long sys_sysinfo(struct sysinfo __user *info) { struct sysinfo val; unsigned long mem_total, sav_total; unsigned int mem_unit, bitcount; unsigned long seq; memset((char *)&val, 0, sizeof(struct sysinfo)); do { struct timespec tp; seq = read_seqbegin(&xtime_lock); /* * This is annoying. The below is the same thing * posix_get_clock_monotonic() does, but it wants to * take the lock which we want to cover the loads stuff * too. */ getnstimeofday(&tp); tp.tv_sec += wall_to_monotonic.tv_sec; tp.tv_nsec += wall_to_monotonic.tv_nsec; if (tp.tv_nsec - NSEC_PER_SEC >= 0) { tp.tv_nsec = tp.tv_nsec - NSEC_PER_SEC; tp.tv_sec++; } val.uptime = tp.tv_sec + (tp.tv_nsec ? 1 : 0); val.loads[0] = avenrun[0] << (SI_LOAD_SHIFT - FSHIFT); val.loads[1] = avenrun[1] << (SI_LOAD_SHIFT - FSHIFT); val.loads[2] = avenrun[2] << (SI_LOAD_SHIFT - FSHIFT); val.procs = nr_threads; } while (read_seqretry(&xtime_lock, seq)); si_meminfo(&val); si_swapinfo(&val); /* * If the sum of all the available memory (i.e. ram + swap) * is less than can be stored in a 32 bit unsigned long then * we can be binary compatible with 2.2.x kernels. If not, * well, in that case 2.2.x was broken anyways... * * -Erik Andersen <andersee@debian.org> */ mem_total = val.totalram + val.totalswap; if (mem_total < val.totalram || mem_total < val.totalswap) goto out; bitcount = 0; mem_unit = val.mem_unit; while (mem_unit > 1) { bitcount++; mem_unit >>= 1; sav_total = mem_total; mem_total <<= 1; if (mem_total < sav_total) goto out; } /* * If mem_total did not overflow, multiply all memory values by * val.mem_unit and set it to 1. This leaves things compatible * with 2.2.x, and also retains compatibility with earlier 2.4.x * kernels... */ val.mem_unit = 1; val.totalram <<= bitcount; val.freeram <<= bitcount; val.sharedram <<= bitcount; val.bufferram <<= bitcount; val.totalswap <<= bitcount; val.freeswap <<= bitcount; val.totalhigh <<= bitcount; val.freehigh <<= bitcount; out: if (copy_to_user(info, &val, sizeof(struct sysinfo))) return -EFAULT; return 0; } /* * lockdep: we want to track each per-CPU base as a separate lock-class, * but timer-bases are kmalloc()-ed, so we need to attach separate * keys to them: */ static struct lock_class_key base_lock_keys[NR_CPUS]; static int __devinit init_timers_cpu(int cpu) { int j; tvec_base_t *base; static char __devinitdata tvec_base_done[NR_CPUS]; if (!tvec_base_done[cpu]) { static char boot_done; if (boot_done) { /* * The APs use this path later in boot */ base = kmalloc_node(sizeof(*base), GFP_KERNEL, cpu_to_node(cpu)); if (!base) return -ENOMEM; memset(base, 0, sizeof(*base)); per_cpu(tvec_bases, cpu) = base; } else { /* * This is for the boot CPU - we use compile-time * static initialisation because per-cpu memory isn't * ready yet and because the memory allocators are not * initialised either. */ boot_done = 1; base = &boot_tvec_bases; } tvec_base_done[cpu] = 1; } else { base = per_cpu(tvec_bases, cpu); } spin_lock_init(&base->lock); lockdep_set_class(&base->lock, base_lock_keys + cpu); for (j = 0; j < TVN_SIZE; j++) { INIT_LIST_HEAD(base->tv5.vec + j); INIT_LIST_HEAD(base->tv4.vec + j); INIT_LIST_HEAD(base->tv3.vec + j); INIT_LIST_HEAD(base->tv2.vec + j); } for (j = 0; j < TVR_SIZE; j++) INIT_LIST_HEAD(base->tv1.vec + j); base->timer_jiffies = jiffies; return 0; } #ifdef CONFIG_HOTPLUG_CPU static void migrate_timer_list(tvec_base_t *new_base, struct list_head *head) { struct timer_list *timer; while (!list_empty(head)) { timer = list_entry(head->next, struct timer_list, entry); detach_timer(timer, 0); timer->base = new_base; internal_add_timer(new_base, timer); } } static void __devinit migrate_timers(int cpu) { tvec_base_t *old_base; tvec_base_t *new_base; int i; BUG_ON(cpu_online(cpu)); old_base = per_cpu(tvec_bases, cpu); new_base = get_cpu_var(tvec_bases); local_irq_disable(); spin_lock(&new_base->lock); spin_lock(&old_base->lock); BUG_ON(old_base->running_timer); for (i = 0; i < TVR_SIZE; i++) migrate_timer_list(new_base, old_base->tv1.vec + i); for (i = 0; i < TVN_SIZE; i++) { migrate_timer_list(new_base, old_base->tv2.vec + i); migrate_timer_list(new_base, old_base->tv3.vec + i); migrate_timer_list(new_base, old_base->tv4.vec + i); migrate_timer_list(new_base, old_base->tv5.vec + i); } spin_unlock(&old_base->lock); spin_unlock(&new_base->lock); local_irq_enable(); put_cpu_var(tvec_bases); } #endif /* CONFIG_HOTPLUG_CPU */ static int __cpuinit timer_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu) { long cpu = (long)hcpu; switch(action) { case CPU_UP_PREPARE: if (init_timers_cpu(cpu) < 0) return NOTIFY_BAD; break; #ifdef CONFIG_HOTPLUG_CPU case CPU_DEAD: migrate_timers(cpu); break; #endif default: break; } return NOTIFY_OK; } static struct notifier_block __cpuinitdata timers_nb = { .notifier_call = timer_cpu_notify, }; void __init init_timers(void) { int err = timer_cpu_notify(&timers_nb, (unsigned long)CPU_UP_PREPARE, (void *)(long)smp_processor_id()); BUG_ON(err == NOTIFY_BAD); register_cpu_notifier(&timers_nb); open_softirq(TIMER_SOFTIRQ, run_timer_softirq, NULL); } #ifdef CONFIG_TIME_INTERPOLATION struct time_interpolator *time_interpolator __read_mostly; static struct time_interpolator *time_interpolator_list __read_mostly; static DEFINE_SPINLOCK(time_interpolator_lock); static inline u64 time_interpolator_get_cycles(unsigned int src) { unsigned long (*x)(void); switch (src) { case TIME_SOURCE_FUNCTION: x = time_interpolator->addr; return x(); case TIME_SOURCE_MMIO64 : return readq_relaxed((void __iomem *)time_interpolator->addr); case TIME_SOURCE_MMIO32 : return readl_relaxed((void __iomem *)time_interpolator->addr); default: return get_cycles(); } } static inline u64 time_interpolator_get_counter(int writelock) { unsigned int src = time_interpolator->source; if (time_interpolator->jitter) { u64 lcycle; u64 now; do { lcycle = time_interpolator->last_cycle; now = time_interpolator_get_cycles(src); if (lcycle && time_after(lcycle, now)) return lcycle; /* When holding the xtime write lock, there's no need * to add the overhead of the cmpxchg. Readers are * force to retry until the write lock is released. */ if (writelock) { time_interpolator->last_cycle = now; return now; } /* Keep track of the last timer value returned. The use of cmpxchg here * will cause contention in an SMP environment. */ } while (unlikely(cmpxchg(&time_interpolator->last_cycle, lcycle, now) != lcycle)); return now; } else return time_interpolator_get_cycles(src); } void time_interpolator_reset(void) { time_interpolator->offset = 0; time_interpolator->last_counter = time_interpolator_get_counter(1); } #define GET_TI_NSECS(count,i) (((((count) - i->last_counter) & (i)->mask) * (i)->nsec_per_cyc) >> (i)->shift) unsigned long time_interpolator_get_offset(void) { /* If we do not have a time interpolator set up then just return zero */ if (!time_interpolator) return 0; return time_interpolator->offset + GET_TI_NSECS(time_interpolator_get_counter(0), time_interpolator); } #define INTERPOLATOR_ADJUST 65536 #define INTERPOLATOR_MAX_SKIP 10*INTERPOLATOR_ADJUST void time_interpolator_update(long delta_nsec) { u64 counter; unsigned long offset; /* If there is no time interpolator set up then do nothing */ if (!time_interpolator) return; /* * The interpolator compensates for late ticks by accumulating the late * time in time_interpolator->offset. A tick earlier than expected will * lead to a reset of the offset and a corresponding jump of the clock * forward. Again this only works if the interpolator clock is running * slightly slower than the regular clock and the tuning logic insures * that. */ counter = time_interpolator_get_counter(1); offset = time_interpolator->offset + GET_TI_NSECS(counter, time_interpolator); if (delta_nsec < 0 || (unsigned long) delta_nsec < offset) time_interpolator->offset = offset - delta_nsec; else { time_interpolator->skips++; time_interpolator->ns_skipped += delta_nsec - offset; time_interpolator->offset = 0; } time_interpolator->last_counter = counter; /* Tuning logic for time interpolator invoked every minute or so. * Decrease interpolator clock speed if no skips occurred and an offset is carried. * Increase interpolator clock speed if we skip too much time. */ if (jiffies % INTERPOLATOR_ADJUST == 0) { if (time_interpolator->skips == 0 && time_interpolator->offset > tick_nsec) time_interpolator->nsec_per_cyc--; if (time_interpolator->ns_skipped > INTERPOLATOR_MAX_SKIP && time_interpolator->offset == 0) time_interpolator->nsec_per_cyc++; time_interpolator->skips = 0; time_interpolator->ns_skipped = 0; } } static inline int is_better_time_interpolator(struct time_interpolator *new) { if (!time_interpolator) return 1; return new->frequency > 2*time_interpolator->frequency || (unsigned long)new->drift < (unsigned long)time_interpolator->drift; } void register_time_interpolator(struct time_interpolator *ti) { unsigned long flags; /* Sanity check */ BUG_ON(ti->frequency == 0 || ti->mask == 0); ti->nsec_per_cyc = ((u64)NSEC_PER_SEC << ti->shift) / ti->frequency; spin_lock(&time_interpolator_lock); write_seqlock_irqsave(&xtime_lock, flags); if (is_better_time_interpolator(ti)) { time_interpolator = ti; time_interpolator_reset(); } write_sequnlock_irqrestore(&xtime_lock, flags); ti->next = time_interpolator_list; time_interpolator_list = ti; spin_unlock(&time_interpolator_lock); } void unregister_time_interpolator(struct time_interpolator *ti) { struct time_interpolator *curr, **prev; unsigned long flags; spin_lock(&time_interpolator_lock); prev = &time_interpolator_list; for (curr = *prev; curr; curr = curr->next) { if (curr == ti) { *prev = curr->next; break; } prev = &curr->next; } write_seqlock_irqsave(&xtime_lock, flags); if (ti == time_interpolator) { /* we lost the best time-interpolator: */ time_interpolator = NULL; /* find the next-best interpolator */ for (curr = time_interpolator_list; curr; curr = curr->next) if (is_better_time_interpolator(curr)) time_interpolator = curr; time_interpolator_reset(); } write_sequnlock_irqrestore(&xtime_lock, flags); spin_unlock(&time_interpolator_lock); } #endif /* CONFIG_TIME_INTERPOLATION */ /** * msleep - sleep safely even with waitqueue interruptions * @msecs: Time in milliseconds to sleep for */ void msleep(unsigned int msecs) { unsigned long timeout = msecs_to_jiffies(msecs) + 1; while (timeout) timeout = schedule_timeout_uninterruptible(timeout); } EXPORT_SYMBOL(msleep); /** * msleep_interruptible - sleep waiting for signals * @msecs: Time in milliseconds to sleep for */ unsigned long msleep_interruptible(unsigned int msecs) { unsigned long timeout = msecs_to_jiffies(msecs) + 1; while (timeout && !signal_pending(current)) timeout = schedule_timeout_interruptible(timeout); return jiffies_to_msecs(timeout); } EXPORT_SYMBOL(msleep_interruptible);