/* * 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 #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef CONFIG_TIME_INTERPOLATION static void time_interpolator_update(long delta_nsec); #else #define time_interpolator_update(x) #endif /* * 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) struct timer_base_s { spinlock_t lock; struct timer_list *running_timer; }; 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 { struct timer_base_s t_base; 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; static DEFINE_PER_CPU(tvec_base_t, tvec_bases); static inline void set_running_timer(tvec_base_t *base, struct timer_list *timer) { #ifdef CONFIG_SMP base->t_base.running_timer = timer; #endif } static void check_timer_failed(struct timer_list *timer) { static int whine_count; if (whine_count < 16) { whine_count++; printk("Uninitialised timer!\n"); printk("This is just a warning. Your computer is OK\n"); printk("function=0x%p, data=0x%lx\n", timer->function, timer->data); dump_stack(); } /* * Now fix it up */ timer->magic = TIMER_MAGIC; } static inline void check_timer(struct timer_list *timer) { if (timer->magic != TIMER_MAGIC) check_timer_failed(timer); } 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); } typedef struct timer_base_s timer_base_t; /* * Used by TIMER_INITIALIZER, we can't use per_cpu(tvec_bases) * at compile time, and we need timer->base to lock the timer. */ timer_base_t __init_timer_base ____cacheline_aligned_in_smp = { .lock = SPIN_LOCK_UNLOCKED }; EXPORT_SYMBOL(__init_timer_base); /*** * 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 = &per_cpu(tvec_bases, raw_smp_processor_id()).t_base; timer->magic = TIMER_MAGIC; } 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).t_base.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 timer_base_t *lock_timer_base(struct timer_list *timer, unsigned long *flags) { timer_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) { timer_base_t *base; tvec_base_t *new_base; unsigned long flags; int ret = 0; BUG_ON(!timer->function); check_timer(timer); 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->t_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 (unlikely(base->running_timer == timer)) { /* The timer remains on a former base */ new_base = container_of(base, tvec_base_t, t_base); } else { /* See the comment in lock_timer_base() */ timer->base = NULL; spin_unlock(&base->lock); spin_lock(&new_base->t_base.lock); timer->base = &new_base->t_base; } } timer->expires = expires; internal_add_timer(new_base, timer); spin_unlock_irqrestore(&new_base->t_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); check_timer(timer); spin_lock_irqsave(&base->t_base.lock, flags); timer->base = &base->t_base; internal_add_timer(base, timer); spin_unlock_irqrestore(&base->t_base.lock, flags); } /*** * mod_timer - modify a timer's timeout * @timer: the timer to be modified * * 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); check_timer(timer); /* * 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) { timer_base_t *base; unsigned long flags; int ret = 0; check_timer(timer); 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 /* * 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) { timer_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) { check_timer(timer); for (;;) { int ret = try_to_del_timer_sync(timer); if (ret >= 0) return ret; } } 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 list_head *head, *curr; head = tv->vec + index; curr = head->next; /* * We are removing _all_ timers from the list, so we don't have to * detach them individually, just clear the list afterwards. */ while (curr != head) { struct timer_list *tmp; tmp = list_entry(curr, struct timer_list, entry); BUG_ON(tmp->base != &base->t_base); curr = curr->next; internal_add_timer(base, tmp); } INIT_LIST_HEAD(head); return index; } /*** * __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. */ #define INDEX(N) (base->timer_jiffies >> (TVR_BITS + N * TVN_BITS)) & TVN_MASK static inline void __run_timers(tvec_base_t *base) { struct timer_list *timer; spin_lock_irq(&base->t_base.lock); while (time_after_eq(jiffies, base->timer_jiffies)) { struct list_head work_list = LIST_HEAD_INIT(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_splice_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->t_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->t_base.lock); } } set_running_timer(base, NULL); spin_unlock_irq(&base->t_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; tvec_t *varray[4]; int i, j; base = &__get_cpu_var(tvec_bases); spin_lock(&base->t_base.lock); expires = base->timer_jiffies + (LONG_MAX >> 1); list = 0; /* 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->t_base.lock); return expires; } #endif /******************************************************************/ /* * Timekeeping variables */ unsigned long tick_usec = TICK_USEC; /* USER_HZ period (usec) */ unsigned long tick_nsec = TICK_NSEC; /* ACTHZ period (nsec) */ /* * 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); /* Don't completely fail for HZ > 500. */ int tickadj = 500/HZ ? : 1; /* microsecs */ /* * phase-lock loop variables */ /* TIME_ERROR prevents overwriting the CMOS clock */ int time_state = TIME_OK; /* clock synchronization status */ int time_status = STA_UNSYNC; /* clock status bits */ long time_offset; /* time adjustment (us) */ long time_constant = 2; /* pll time constant */ long time_tolerance = MAXFREQ; /* frequency tolerance (ppm) */ long time_precision = 1; /* clock precision (us) */ long time_maxerror = NTP_PHASE_LIMIT; /* maximum error (us) */ long time_esterror = NTP_PHASE_LIMIT; /* estimated error (us) */ static long time_phase; /* phase offset (scaled us) */ long time_freq = (((NSEC_PER_SEC + HZ/2) % HZ - HZ/2) << SHIFT_USEC) / NSEC_PER_USEC; /* frequency offset (scaled ppm)*/ static long time_adj; /* tick adjust (scaled 1 / HZ) */ long time_reftime; /* time at last adjustment (s) */ long time_adjust; long time_next_adjust; /* * this routine handles the overflow of the microsecond field * * The tricky bits of code to handle the accurate clock support * were provided by Dave Mills (Mills@UDEL.EDU) of NTP fame. * They were originally developed for SUN and DEC kernels. * All the kudos should go to Dave for this stuff. * */ static void second_overflow(void) { long ltemp; /* Bump the maxerror field */ time_maxerror += time_tolerance >> SHIFT_USEC; if ( time_maxerror > NTP_PHASE_LIMIT ) { time_maxerror = NTP_PHASE_LIMIT; time_status |= STA_UNSYNC; } /* * Leap second processing. If in leap-insert state at * the end of the day, the system clock is set back one * second; if in leap-delete state, the system clock is * set ahead one second. The microtime() routine or * external clock driver will insure that reported time * is always monotonic. The ugly divides should be * replaced. */ switch (time_state) { case TIME_OK: if (time_status & STA_INS) time_state = TIME_INS; else if (time_status & STA_DEL) time_state = TIME_DEL; break; case TIME_INS: if (xtime.tv_sec % 86400 == 0) { xtime.tv_sec--; wall_to_monotonic.tv_sec++; /* The timer interpolator will make time change gradually instead * of an immediate jump by one second. */ time_interpolator_update(-NSEC_PER_SEC); time_state = TIME_OOP; clock_was_set(); printk(KERN_NOTICE "Clock: inserting leap second 23:59:60 UTC\n"); } break; case TIME_DEL: if ((xtime.tv_sec + 1) % 86400 == 0) { xtime.tv_sec++; wall_to_monotonic.tv_sec--; /* Use of time interpolator for a gradual change of time */ time_interpolator_update(NSEC_PER_SEC); time_state = TIME_WAIT; clock_was_set(); printk(KERN_NOTICE "Clock: deleting leap second 23:59:59 UTC\n"); } break; case TIME_OOP: time_state = TIME_WAIT; break; case TIME_WAIT: if (!(time_status & (STA_INS | STA_DEL))) time_state = TIME_OK; } /* * Compute the phase adjustment for the next second. In * PLL mode, the offset is reduced by a fixed factor * times the time constant. In FLL mode the offset is * used directly. In either mode, the maximum phase * adjustment for each second is clamped so as to spread * the adjustment over not more than the number of * seconds between updates. */ if (time_offset < 0) { ltemp = -time_offset; if (!(time_status & STA_FLL)) ltemp >>= SHIFT_KG + time_constant; if (ltemp > (MAXPHASE / MINSEC) << SHIFT_UPDATE) ltemp = (MAXPHASE / MINSEC) << SHIFT_UPDATE; time_offset += ltemp; time_adj = -ltemp << (SHIFT_SCALE - SHIFT_HZ - SHIFT_UPDATE); } else { ltemp = time_offset; if (!(time_status & STA_FLL)) ltemp >>= SHIFT_KG + time_constant; if (ltemp > (MAXPHASE / MINSEC) << SHIFT_UPDATE) ltemp = (MAXPHASE / MINSEC) << SHIFT_UPDATE; time_offset -= ltemp; time_adj = ltemp << (SHIFT_SCALE - SHIFT_HZ - SHIFT_UPDATE); } /* * Compute the frequency estimate and additional phase * adjustment due to frequency error for the next * second. When the PPS signal is engaged, gnaw on the * watchdog counter and update the frequency computed by * the pll and the PPS signal. */ pps_valid++; if (pps_valid == PPS_VALID) { /* PPS signal lost */ pps_jitter = MAXTIME; pps_stabil = MAXFREQ; time_status &= ~(STA_PPSSIGNAL | STA_PPSJITTER | STA_PPSWANDER | STA_PPSERROR); } ltemp = time_freq + pps_freq; if (ltemp < 0) time_adj -= -ltemp >> (SHIFT_USEC + SHIFT_HZ - SHIFT_SCALE); else time_adj += ltemp >> (SHIFT_USEC + SHIFT_HZ - SHIFT_SCALE); #if HZ == 100 /* Compensate for (HZ==100) != (1 << SHIFT_HZ). * Add 25% and 3.125% to get 128.125; => only 0.125% error (p. 14) */ if (time_adj < 0) time_adj -= (-time_adj >> 2) + (-time_adj >> 5); else time_adj += (time_adj >> 2) + (time_adj >> 5); #endif #if HZ == 1000 /* Compensate for (HZ==1000) != (1 << SHIFT_HZ). * Add 1.5625% and 0.78125% to get 1023.4375; => only 0.05% error (p. 14) */ if (time_adj < 0) time_adj -= (-time_adj >> 6) + (-time_adj >> 7); else time_adj += (time_adj >> 6) + (time_adj >> 7); #endif } /* in the NTP reference this is called "hardclock()" */ static void update_wall_time_one_tick(void) { long time_adjust_step, delta_nsec; if ( (time_adjust_step = time_adjust) != 0 ) { /* We are doing an adjtime thing. * * Prepare time_adjust_step to be within bounds. * Note that a positive time_adjust means we want the clock * to run faster. * * Limit the amount of the step to be in the range * -tickadj .. +tickadj */ if (time_adjust > tickadj) time_adjust_step = tickadj; else if (time_adjust < -tickadj) time_adjust_step = -tickadj; /* Reduce by this step the amount of time left */ time_adjust -= time_adjust_step; } delta_nsec = tick_nsec + time_adjust_step * 1000; /* * Advance the phase, once it gets to one microsecond, then * advance the tick more. */ time_phase += time_adj; if (time_phase <= -FINENSEC) { long ltemp = -time_phase >> (SHIFT_SCALE - 10); time_phase += ltemp << (SHIFT_SCALE - 10); delta_nsec -= ltemp; } else if (time_phase >= FINENSEC) { long ltemp = time_phase >> (SHIFT_SCALE - 10); time_phase -= ltemp << (SHIFT_SCALE - 10); delta_nsec += ltemp; } xtime.tv_nsec += delta_nsec; time_interpolator_update(delta_nsec); /* Changes by adjtime() do not take effect till next tick. */ if (time_next_adjust != 0) { time_adjust = time_next_adjust; time_next_adjust = 0; } } /* * Using a loop looks inefficient, but "ticks" is * usually just one (we shouldn't be losing ticks, * we're doing this this way mainly for interrupt * latency reasons, not because we think we'll * have lots of lost timer ticks */ static void update_wall_time(unsigned long ticks) { do { ticks--; update_wall_time_one_tick(); if (xtime.tv_nsec >= 1000000000) { xtime.tv_nsec -= 1000000000; xtime.tv_sec++; second_overflow(); } } while (ticks); } /* * 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_running() + nr_uninterruptible()) * 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; count -= ticks; if (count < 0) { count += LOAD_FREQ; active_tasks = count_active_tasks(); CALC_LOAD(avenrun[0], EXP_1, active_tasks); CALC_LOAD(avenrun[1], EXP_5, active_tasks); CALC_LOAD(avenrun[2], EXP_15, active_tasks); } } /* jiffies at the most recent update of wall time */ unsigned long wall_jiffies = INITIAL_JIFFIES; /* * This read-write spinlock protects us from races in SMP while * playing with xtime and avenrun. */ #ifndef ARCH_HAVE_XTIME_LOCK seqlock_t xtime_lock __cacheline_aligned_in_smp = SEQLOCK_UNLOCKED; 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); 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); } /* * Called by the timer interrupt. xtime_lock must already be taken * by the timer IRQ! */ static inline void update_times(void) { unsigned long ticks; ticks = jiffies - wall_jiffies; if (ticks) { wall_jiffies += ticks; update_wall_time(ticks); } 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(struct pt_regs *regs) { jiffies_64++; update_times(); } #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) { struct itimerval it_new, it_old; unsigned int oldalarm; it_new.it_interval.tv_sec = it_new.it_interval.tv_usec = 0; it_new.it_value.tv_sec = seconds; it_new.it_value.tv_usec = 0; do_setitimer(ITIMER_REAL, &it_new, &it_old); oldalarm = it_old.it_value.tv_sec; /* ehhh.. We can't return 0 if we have an alarm pending.. */ /* And we'd better return too much than too little anyway */ if ((!oldalarm && it_old.it_value.tv_usec) || it_old.it_value.tv_usec >= 500000) oldalarm++; return oldalarm; } #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 ->group_leader->real_parent is not SMP-safe, it could * change from under us. However, rather than getting any lock * we can use an optimistic algorithm: get the parent * pid, and go back and check that the parent is still * the same. If it has changed (which is extremely unlikely * indeed), we just try again.. * * NOTE! This depends on the fact that even if we _do_ * get an old value of "parent", we can happily dereference * the pointer (it was and remains a dereferencable kernel pointer * no matter what): we just can't necessarily trust the result * until we know that the parent pointer is valid. * * NOTE2: ->group_leader never changes from under us. */ asmlinkage long sys_getppid(void) { int pid; struct task_struct *me = current; struct task_struct *parent; parent = me->group_leader->real_parent; for (;;) { pid = parent->tgid; #ifdef CONFIG_SMP { struct task_struct *old = parent; /* * Make sure we read the pid before re-reading the * parent pointer: */ smp_rmb(); parent = me->group_leader->real_parent; if (old != parent) continue; } #endif break; } 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((task_t *)__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; init_timer(&timer); timer.expires = expire; timer.data = (unsigned long) current; timer.function = process_timeout; add_timer(&timer); schedule(); del_singleshot_timer_sync(&timer); timeout = expire - jiffies; out: return timeout < 0 ? 0 : timeout; } EXPORT_SYMBOL(schedule_timeout); /* Thread ID - the internal kernel "pid" */ asmlinkage long sys_gettid(void) { return current->pid; } static long __sched nanosleep_restart(struct restart_block *restart) { unsigned long expire = restart->arg0, now = jiffies; struct timespec __user *rmtp = (struct timespec __user *) restart->arg1; long ret; /* Did it expire while we handled signals? */ if (!time_after(expire, now)) return 0; current->state = TASK_INTERRUPTIBLE; expire = schedule_timeout(expire - now); ret = 0; if (expire) { struct timespec t; jiffies_to_timespec(expire, &t); ret = -ERESTART_RESTARTBLOCK; if (rmtp && copy_to_user(rmtp, &t, sizeof(t))) ret = -EFAULT; /* The 'restart' block is already filled in */ } return ret; } asmlinkage long sys_nanosleep(struct timespec __user *rqtp, struct timespec __user *rmtp) { struct timespec t; unsigned long expire; long ret; if (copy_from_user(&t, rqtp, sizeof(t))) return -EFAULT; if ((t.tv_nsec >= 1000000000L) || (t.tv_nsec < 0) || (t.tv_sec < 0)) return -EINVAL; expire = timespec_to_jiffies(&t) + (t.tv_sec || t.tv_nsec); current->state = TASK_INTERRUPTIBLE; expire = schedule_timeout(expire); ret = 0; if (expire) { struct restart_block *restart; jiffies_to_timespec(expire, &t); if (rmtp && copy_to_user(rmtp, &t, sizeof(t))) return -EFAULT; restart = ¤t_thread_info()->restart_block; restart->fn = nanosleep_restart; restart->arg0 = jiffies + expire; restart->arg1 = (unsigned long) rmtp; ret = -ERESTART_RESTARTBLOCK; } return ret; } /* * sys_sysinfo - fill in sysinfo struct */ 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 */ 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; } static void __devinit init_timers_cpu(int cpu) { int j; tvec_base_t *base; base = &per_cpu(tvec_bases, cpu); spin_lock_init(&base->t_base.lock); 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; } #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->t_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->t_base.lock); spin_lock(&old_base->t_base.lock); if (old_base->t_base.running_timer) BUG(); 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->t_base.lock); spin_unlock(&new_base->t_base.lock); local_irq_enable(); put_cpu_var(tvec_bases); } #endif /* CONFIG_HOTPLUG_CPU */ static int __devinit timer_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu) { long cpu = (long)hcpu; switch(action) { case CPU_UP_PREPARE: init_timers_cpu(cpu); break; #ifdef CONFIG_HOTPLUG_CPU case CPU_DEAD: migrate_timers(cpu); break; #endif default: break; } return NOTIFY_OK; } static struct notifier_block __devinitdata timers_nb = { .notifier_call = timer_cpu_notify, }; void __init init_timers(void) { timer_cpu_notify(&timers_nb, (unsigned long)CPU_UP_PREPARE, (void *)(long)smp_processor_id()); register_cpu_notifier(&timers_nb); open_softirq(TIMER_SOFTIRQ, run_timer_softirq, NULL); } #ifdef CONFIG_TIME_INTERPOLATION struct time_interpolator *time_interpolator; static struct time_interpolator *time_interpolator_list; 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((void __iomem *) time_interpolator->addr); case TIME_SOURCE_MMIO32 : return readl((void __iomem *) time_interpolator->addr); default: return get_cycles(); } } static inline u64 time_interpolator_get_counter(void) { 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; /* 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(); } #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(), time_interpolator); } #define INTERPOLATOR_ADJUST 65536 #define INTERPOLATOR_MAX_SKIP 10*INTERPOLATOR_ADJUST static 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(); 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 */ if (ti->frequency == 0 || ti->mask == 0) BUG(); 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) { set_current_state(TASK_UNINTERRUPTIBLE); timeout = schedule_timeout(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)) { set_current_state(TASK_INTERRUPTIBLE); timeout = schedule_timeout(timeout); } return jiffies_to_msecs(timeout); } EXPORT_SYMBOL(msleep_interruptible);