/* * linux/kernel/hrtimer.c * * Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de> * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar * Copyright(C) 2006-2007 Timesys Corp., Thomas Gleixner * * High-resolution kernel timers * * In contrast to the low-resolution timeout API implemented in * kernel/timer.c, hrtimers provide finer resolution and accuracy * depending on system configuration and capabilities. * * These timers are currently used for: * - itimers * - POSIX timers * - nanosleep * - precise in-kernel timing * * Started by: Thomas Gleixner and Ingo Molnar * * Credits: * based on kernel/timer.c * * Help, testing, suggestions, bugfixes, improvements were * provided by: * * George Anzinger, Andrew Morton, Steven Rostedt, Roman Zippel * et. al. * * For licencing details see kernel-base/COPYING */ #include <linux/cpu.h> #include <linux/irq.h> #include <linux/module.h> #include <linux/percpu.h> #include <linux/hrtimer.h> #include <linux/notifier.h> #include <linux/syscalls.h> #include <linux/kallsyms.h> #include <linux/interrupt.h> #include <linux/tick.h> #include <linux/seq_file.h> #include <linux/err.h> #include <asm/uaccess.h> /** * ktime_get - get the monotonic time in ktime_t format * * returns the time in ktime_t format */ ktime_t ktime_get(void) { struct timespec now; ktime_get_ts(&now); return timespec_to_ktime(now); } EXPORT_SYMBOL_GPL(ktime_get); /** * ktime_get_real - get the real (wall-) time in ktime_t format * * returns the time in ktime_t format */ ktime_t ktime_get_real(void) { struct timespec now; getnstimeofday(&now); return timespec_to_ktime(now); } EXPORT_SYMBOL_GPL(ktime_get_real); /* * The timer bases: * * Note: If we want to add new timer bases, we have to skip the two * clock ids captured by the cpu-timers. We do this by holding empty * entries rather than doing math adjustment of the clock ids. * This ensures that we capture erroneous accesses to these clock ids * rather than moving them into the range of valid clock id's. */ DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) = { .clock_base = { { .index = CLOCK_REALTIME, .get_time = &ktime_get_real, .resolution = KTIME_LOW_RES, }, { .index = CLOCK_MONOTONIC, .get_time = &ktime_get, .resolution = KTIME_LOW_RES, }, } }; /** * ktime_get_ts - get the monotonic clock in timespec format * @ts: pointer to timespec variable * * The function calculates the monotonic clock from the realtime * clock and the wall_to_monotonic offset and stores the result * in normalized timespec format in the variable pointed to by @ts. */ void ktime_get_ts(struct timespec *ts) { struct timespec tomono; unsigned long seq; do { seq = read_seqbegin(&xtime_lock); getnstimeofday(ts); tomono = wall_to_monotonic; } while (read_seqretry(&xtime_lock, seq)); set_normalized_timespec(ts, ts->tv_sec + tomono.tv_sec, ts->tv_nsec + tomono.tv_nsec); } EXPORT_SYMBOL_GPL(ktime_get_ts); /* * Get the coarse grained time at the softirq based on xtime and * wall_to_monotonic. */ static void hrtimer_get_softirq_time(struct hrtimer_cpu_base *base) { ktime_t xtim, tomono; struct timespec xts, tom; unsigned long seq; do { seq = read_seqbegin(&xtime_lock); xts = current_kernel_time(); tom = wall_to_monotonic; } while (read_seqretry(&xtime_lock, seq)); xtim = timespec_to_ktime(xts); tomono = timespec_to_ktime(tom); base->clock_base[CLOCK_REALTIME].softirq_time = xtim; base->clock_base[CLOCK_MONOTONIC].softirq_time = ktime_add(xtim, tomono); } /* * Helper function to check, whether the timer is running the callback * function */ static inline int hrtimer_callback_running(struct hrtimer *timer) { return timer->state & HRTIMER_STATE_CALLBACK; } /* * Functions and macros which are different for UP/SMP systems are kept in a * single place */ #ifdef CONFIG_SMP /* * We are using hashed locking: holding per_cpu(hrtimer_bases)[n].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 the lists/queues. * * 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 struct hrtimer_clock_base *lock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags) { struct hrtimer_clock_base *base; for (;;) { base = timer->base; if (likely(base != NULL)) { spin_lock_irqsave(&base->cpu_base->lock, *flags); if (likely(base == timer->base)) return base; /* The timer has migrated to another CPU: */ spin_unlock_irqrestore(&base->cpu_base->lock, *flags); } cpu_relax(); } } /* * Switch the timer base to the current CPU when possible. */ static inline struct hrtimer_clock_base * switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base) { struct hrtimer_clock_base *new_base; struct hrtimer_cpu_base *new_cpu_base; new_cpu_base = &__get_cpu_var(hrtimer_bases); new_base = &new_cpu_base->clock_base[base->index]; 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, * so we keep it on the same CPU. No hassle vs. reprogramming * the event source in the high resolution case. The softirq * code will take care of this when the timer function has * completed. There is no conflict as we hold the lock until * the timer is enqueued. */ if (unlikely(hrtimer_callback_running(timer))) return base; /* See the comment in lock_timer_base() */ timer->base = NULL; spin_unlock(&base->cpu_base->lock); spin_lock(&new_base->cpu_base->lock); timer->base = new_base; } return new_base; } #else /* CONFIG_SMP */ static inline struct hrtimer_clock_base * lock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags) { struct hrtimer_clock_base *base = timer->base; spin_lock_irqsave(&base->cpu_base->lock, *flags); return base; } # define switch_hrtimer_base(t, b) (b) #endif /* !CONFIG_SMP */ /* * Functions for the union type storage format of ktime_t which are * too large for inlining: */ #if BITS_PER_LONG < 64 # ifndef CONFIG_KTIME_SCALAR /** * ktime_add_ns - Add a scalar nanoseconds value to a ktime_t variable * @kt: addend * @nsec: the scalar nsec value to add * * Returns the sum of kt and nsec in ktime_t format */ ktime_t ktime_add_ns(const ktime_t kt, u64 nsec) { ktime_t tmp; if (likely(nsec < NSEC_PER_SEC)) { tmp.tv64 = nsec; } else { unsigned long rem = do_div(nsec, NSEC_PER_SEC); tmp = ktime_set((long)nsec, rem); } return ktime_add(kt, tmp); } EXPORT_SYMBOL_GPL(ktime_add_ns); /** * ktime_sub_ns - Subtract a scalar nanoseconds value from a ktime_t variable * @kt: minuend * @nsec: the scalar nsec value to subtract * * Returns the subtraction of @nsec from @kt in ktime_t format */ ktime_t ktime_sub_ns(const ktime_t kt, u64 nsec) { ktime_t tmp; if (likely(nsec < NSEC_PER_SEC)) { tmp.tv64 = nsec; } else { unsigned long rem = do_div(nsec, NSEC_PER_SEC); tmp = ktime_set((long)nsec, rem); } return ktime_sub(kt, tmp); } EXPORT_SYMBOL_GPL(ktime_sub_ns); # endif /* !CONFIG_KTIME_SCALAR */ /* * Divide a ktime value by a nanosecond value */ unsigned long ktime_divns(const ktime_t kt, s64 div) { u64 dclc, inc, dns; int sft = 0; dclc = dns = ktime_to_ns(kt); inc = div; /* Make sure the divisor is less than 2^32: */ while (div >> 32) { sft++; div >>= 1; } dclc >>= sft; do_div(dclc, (unsigned long) div); return (unsigned long) dclc; } #endif /* BITS_PER_LONG >= 64 */ /* * Check, whether the timer is on the callback pending list */ static inline int hrtimer_cb_pending(const struct hrtimer *timer) { return timer->state & HRTIMER_STATE_PENDING; } /* * Remove a timer from the callback pending list */ static inline void hrtimer_remove_cb_pending(struct hrtimer *timer) { list_del_init(&timer->cb_entry); } /* High resolution timer related functions */ #ifdef CONFIG_HIGH_RES_TIMERS /* * High resolution timer enabled ? */ static int hrtimer_hres_enabled __read_mostly = 1; /* * Enable / Disable high resolution mode */ static int __init setup_hrtimer_hres(char *str) { if (!strcmp(str, "off")) hrtimer_hres_enabled = 0; else if (!strcmp(str, "on")) hrtimer_hres_enabled = 1; else return 0; return 1; } __setup("highres=", setup_hrtimer_hres); /* * hrtimer_high_res_enabled - query, if the highres mode is enabled */ static inline int hrtimer_is_hres_enabled(void) { return hrtimer_hres_enabled; } /* * Is the high resolution mode active ? */ static inline int hrtimer_hres_active(void) { return __get_cpu_var(hrtimer_bases).hres_active; } /* * Reprogram the event source with checking both queues for the * next event * Called with interrupts disabled and base->lock held */ static void hrtimer_force_reprogram(struct hrtimer_cpu_base *cpu_base) { int i; struct hrtimer_clock_base *base = cpu_base->clock_base; ktime_t expires; cpu_base->expires_next.tv64 = KTIME_MAX; for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++, base++) { struct hrtimer *timer; if (!base->first) continue; timer = rb_entry(base->first, struct hrtimer, node); expires = ktime_sub(timer->expires, base->offset); if (expires.tv64 < cpu_base->expires_next.tv64) cpu_base->expires_next = expires; } if (cpu_base->expires_next.tv64 != KTIME_MAX) tick_program_event(cpu_base->expires_next, 1); } /* * Shared reprogramming for clock_realtime and clock_monotonic * * When a timer is enqueued and expires earlier than the already enqueued * timers, we have to check, whether it expires earlier than the timer for * which the clock event device was armed. * * Called with interrupts disabled and base->cpu_base.lock held */ static int hrtimer_reprogram(struct hrtimer *timer, struct hrtimer_clock_base *base) { ktime_t *expires_next = &__get_cpu_var(hrtimer_bases).expires_next; ktime_t expires = ktime_sub(timer->expires, base->offset); int res; /* * When the callback is running, we do not reprogram the clock event * device. The timer callback is either running on a different CPU or * the callback is executed in the hrtimer_interrupt context. The * reprogramming is handled either by the softirq, which called the * callback or at the end of the hrtimer_interrupt. */ if (hrtimer_callback_running(timer)) return 0; if (expires.tv64 >= expires_next->tv64) return 0; /* * Clockevents returns -ETIME, when the event was in the past. */ res = tick_program_event(expires, 0); if (!IS_ERR_VALUE(res)) *expires_next = expires; return res; } /* * Retrigger next event is called after clock was set * * Called with interrupts disabled via on_each_cpu() */ static void retrigger_next_event(void *arg) { struct hrtimer_cpu_base *base; struct timespec realtime_offset; unsigned long seq; if (!hrtimer_hres_active()) return; do { seq = read_seqbegin(&xtime_lock); set_normalized_timespec(&realtime_offset, -wall_to_monotonic.tv_sec, -wall_to_monotonic.tv_nsec); } while (read_seqretry(&xtime_lock, seq)); base = &__get_cpu_var(hrtimer_bases); /* Adjust CLOCK_REALTIME offset */ spin_lock(&base->lock); base->clock_base[CLOCK_REALTIME].offset = timespec_to_ktime(realtime_offset); hrtimer_force_reprogram(base); spin_unlock(&base->lock); } /* * Clock realtime was set * * Change the offset of the realtime clock vs. the monotonic * clock. * * We might have to reprogram the high resolution timer interrupt. On * SMP we call the architecture specific code to retrigger _all_ high * resolution timer interrupts. On UP we just disable interrupts and * call the high resolution interrupt code. */ void clock_was_set(void) { /* Retrigger the CPU local events everywhere */ on_each_cpu(retrigger_next_event, NULL, 0, 1); } /* * During resume we might have to reprogram the high resolution timer * interrupt (on the local CPU): */ void hres_timers_resume(void) { WARN_ON_ONCE(num_online_cpus() > 1); /* Retrigger the CPU local events: */ retrigger_next_event(NULL); } /* * Initialize the high resolution related parts of cpu_base */ static inline void hrtimer_init_hres(struct hrtimer_cpu_base *base) { base->expires_next.tv64 = KTIME_MAX; base->hres_active = 0; } /* * Initialize the high resolution related parts of a hrtimer */ static inline void hrtimer_init_timer_hres(struct hrtimer *timer) { } /* * When High resolution timers are active, try to reprogram. Note, that in case * the state has HRTIMER_STATE_CALLBACK set, no reprogramming and no expiry * check happens. The timer gets enqueued into the rbtree. The reprogramming * and expiry check is done in the hrtimer_interrupt or in the softirq. */ static inline int hrtimer_enqueue_reprogram(struct hrtimer *timer, struct hrtimer_clock_base *base) { if (base->cpu_base->hres_active && hrtimer_reprogram(timer, base)) { /* Timer is expired, act upon the callback mode */ switch(timer->cb_mode) { case HRTIMER_CB_IRQSAFE_NO_RESTART: /* * We can call the callback from here. No restart * happens, so no danger of recursion */ BUG_ON(timer->function(timer) != HRTIMER_NORESTART); return 1; case HRTIMER_CB_IRQSAFE_NO_SOFTIRQ: /* * This is solely for the sched tick emulation with * dynamic tick support to ensure that we do not * restart the tick right on the edge and end up with * the tick timer in the softirq ! The calling site * takes care of this. */ return 1; case HRTIMER_CB_IRQSAFE: case HRTIMER_CB_SOFTIRQ: /* * Move everything else into the softirq pending list ! */ list_add_tail(&timer->cb_entry, &base->cpu_base->cb_pending); timer->state = HRTIMER_STATE_PENDING; raise_softirq(HRTIMER_SOFTIRQ); return 1; default: BUG(); } } return 0; } /* * Switch to high resolution mode */ static int hrtimer_switch_to_hres(void) { int cpu = smp_processor_id(); struct hrtimer_cpu_base *base = &per_cpu(hrtimer_bases, cpu); unsigned long flags; if (base->hres_active) return 1; local_irq_save(flags); if (tick_init_highres()) { local_irq_restore(flags); printk(KERN_WARNING "Could not switch to high resolution " "mode on CPU %d\n", cpu); return 0; } base->hres_active = 1; base->clock_base[CLOCK_REALTIME].resolution = KTIME_HIGH_RES; base->clock_base[CLOCK_MONOTONIC].resolution = KTIME_HIGH_RES; tick_setup_sched_timer(); /* "Retrigger" the interrupt to get things going */ retrigger_next_event(NULL); local_irq_restore(flags); printk(KERN_DEBUG "Switched to high resolution mode on CPU %d\n", smp_processor_id()); return 1; } #else static inline int hrtimer_hres_active(void) { return 0; } static inline int hrtimer_is_hres_enabled(void) { return 0; } static inline int hrtimer_switch_to_hres(void) { return 0; } static inline void hrtimer_force_reprogram(struct hrtimer_cpu_base *base) { } static inline int hrtimer_enqueue_reprogram(struct hrtimer *timer, struct hrtimer_clock_base *base) { return 0; } static inline void hrtimer_init_hres(struct hrtimer_cpu_base *base) { } static inline void hrtimer_init_timer_hres(struct hrtimer *timer) { } static inline int hrtimer_reprogram(struct hrtimer *timer, struct hrtimer_clock_base *base) { return 0; } #endif /* CONFIG_HIGH_RES_TIMERS */ #ifdef CONFIG_TIMER_STATS void __timer_stats_hrtimer_set_start_info(struct hrtimer *timer, void *addr) { if (timer->start_site) return; timer->start_site = addr; memcpy(timer->start_comm, current->comm, TASK_COMM_LEN); timer->start_pid = current->pid; } #endif /* * Counterpart to lock_hrtimer_base above: */ static inline void unlock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags) { spin_unlock_irqrestore(&timer->base->cpu_base->lock, *flags); } /** * hrtimer_forward - forward the timer expiry * @timer: hrtimer to forward * @now: forward past this time * @interval: the interval to forward * * Forward the timer expiry so it will expire in the future. * Returns the number of overruns. */ unsigned long hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval) { unsigned long orun = 1; ktime_t delta; delta = ktime_sub(now, timer->expires); if (delta.tv64 < 0) return 0; if (interval.tv64 < timer->base->resolution.tv64) interval.tv64 = timer->base->resolution.tv64; if (unlikely(delta.tv64 >= interval.tv64)) { s64 incr = ktime_to_ns(interval); orun = ktime_divns(delta, incr); timer->expires = ktime_add_ns(timer->expires, incr * orun); if (timer->expires.tv64 > now.tv64) return orun; /* * This (and the ktime_add() below) is the * correction for exact: */ orun++; } timer->expires = ktime_add(timer->expires, interval); /* * Make sure, that the result did not wrap with a very large * interval. */ if (timer->expires.tv64 < 0) timer->expires = ktime_set(KTIME_SEC_MAX, 0); return orun; } EXPORT_SYMBOL_GPL(hrtimer_forward); /* * enqueue_hrtimer - internal function to (re)start a timer * * The timer is inserted in expiry order. Insertion into the * red black tree is O(log(n)). Must hold the base lock. */ static void enqueue_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base, int reprogram) { struct rb_node **link = &base->active.rb_node; struct rb_node *parent = NULL; struct hrtimer *entry; int leftmost = 1; /* * Find the right place in the rbtree: */ while (*link) { parent = *link; entry = rb_entry(parent, struct hrtimer, node); /* * We dont care about collisions. Nodes with * the same expiry time stay together. */ if (timer->expires.tv64 < entry->expires.tv64) { link = &(*link)->rb_left; } else { link = &(*link)->rb_right; leftmost = 0; } } /* * Insert the timer to the rbtree and check whether it * replaces the first pending timer */ if (leftmost) { /* * Reprogram the clock event device. When the timer is already * expired hrtimer_enqueue_reprogram has either called the * callback or added it to the pending list and raised the * softirq. * * This is a NOP for !HIGHRES */ if (reprogram && hrtimer_enqueue_reprogram(timer, base)) return; base->first = &timer->node; } rb_link_node(&timer->node, parent, link); rb_insert_color(&timer->node, &base->active); /* * HRTIMER_STATE_ENQUEUED is or'ed to the current state to preserve the * state of a possibly running callback. */ timer->state |= HRTIMER_STATE_ENQUEUED; } /* * __remove_hrtimer - internal function to remove a timer * * Caller must hold the base lock. * * High resolution timer mode reprograms the clock event device when the * timer is the one which expires next. The caller can disable this by setting * reprogram to zero. This is useful, when the context does a reprogramming * anyway (e.g. timer interrupt) */ static void __remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base, unsigned long newstate, int reprogram) { /* High res. callback list. NOP for !HIGHRES */ if (hrtimer_cb_pending(timer)) hrtimer_remove_cb_pending(timer); else { /* * Remove the timer from the rbtree and replace the * first entry pointer if necessary. */ if (base->first == &timer->node) { base->first = rb_next(&timer->node); /* Reprogram the clock event device. if enabled */ if (reprogram && hrtimer_hres_active()) hrtimer_force_reprogram(base->cpu_base); } rb_erase(&timer->node, &base->active); } timer->state = newstate; } /* * remove hrtimer, called with base lock held */ static inline int remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base) { if (hrtimer_is_queued(timer)) { int reprogram; /* * Remove the timer and force reprogramming when high * resolution mode is active and the timer is on the current * CPU. If we remove a timer on another CPU, reprogramming is * skipped. The interrupt event on this CPU is fired and * reprogramming happens in the interrupt handler. This is a * rare case and less expensive than a smp call. */ timer_stats_hrtimer_clear_start_info(timer); reprogram = base->cpu_base == &__get_cpu_var(hrtimer_bases); __remove_hrtimer(timer, base, HRTIMER_STATE_INACTIVE, reprogram); return 1; } return 0; } /** * hrtimer_start - (re)start an relative timer on the current CPU * @timer: the timer to be added * @tim: expiry time * @mode: expiry mode: absolute (HRTIMER_ABS) or relative (HRTIMER_REL) * * Returns: * 0 on success * 1 when the timer was active */ int hrtimer_start(struct hrtimer *timer, ktime_t tim, const enum hrtimer_mode mode) { struct hrtimer_clock_base *base, *new_base; unsigned long flags; int ret; base = lock_hrtimer_base(timer, &flags); /* Remove an active timer from the queue: */ ret = remove_hrtimer(timer, base); /* Switch the timer base, if necessary: */ new_base = switch_hrtimer_base(timer, base); if (mode == HRTIMER_MODE_REL) { tim = ktime_add(tim, new_base->get_time()); /* * CONFIG_TIME_LOW_RES is a temporary way for architectures * to signal that they simply return xtime in * do_gettimeoffset(). In this case we want to round up by * resolution when starting a relative timer, to avoid short * timeouts. This will go away with the GTOD framework. */ #ifdef CONFIG_TIME_LOW_RES tim = ktime_add(tim, base->resolution); #endif /* * Careful here: User space might have asked for a * very long sleep, so the add above might result in a * negative number, which enqueues the timer in front * of the queue. */ if (tim.tv64 < 0) tim.tv64 = KTIME_MAX; } timer->expires = tim; timer_stats_hrtimer_set_start_info(timer); /* * Only allow reprogramming if the new base is on this CPU. * (it might still be on another CPU if the timer was pending) */ enqueue_hrtimer(timer, new_base, new_base->cpu_base == &__get_cpu_var(hrtimer_bases)); unlock_hrtimer_base(timer, &flags); return ret; } EXPORT_SYMBOL_GPL(hrtimer_start); /** * hrtimer_try_to_cancel - try to deactivate a timer * @timer: hrtimer to stop * * Returns: * 0 when the timer was not active * 1 when the timer was active * -1 when the timer is currently excuting the callback function and * cannot be stopped */ int hrtimer_try_to_cancel(struct hrtimer *timer) { struct hrtimer_clock_base *base; unsigned long flags; int ret = -1; base = lock_hrtimer_base(timer, &flags); if (!hrtimer_callback_running(timer)) ret = remove_hrtimer(timer, base); unlock_hrtimer_base(timer, &flags); return ret; } EXPORT_SYMBOL_GPL(hrtimer_try_to_cancel); /** * hrtimer_cancel - cancel a timer and wait for the handler to finish. * @timer: the timer to be cancelled * * Returns: * 0 when the timer was not active * 1 when the timer was active */ int hrtimer_cancel(struct hrtimer *timer) { for (;;) { int ret = hrtimer_try_to_cancel(timer); if (ret >= 0) return ret; cpu_relax(); } } EXPORT_SYMBOL_GPL(hrtimer_cancel); /** * hrtimer_get_remaining - get remaining time for the timer * @timer: the timer to read */ ktime_t hrtimer_get_remaining(const struct hrtimer *timer) { struct hrtimer_clock_base *base; unsigned long flags; ktime_t rem; base = lock_hrtimer_base(timer, &flags); rem = ktime_sub(timer->expires, base->get_time()); unlock_hrtimer_base(timer, &flags); return rem; } EXPORT_SYMBOL_GPL(hrtimer_get_remaining); #if defined(CONFIG_NO_IDLE_HZ) || defined(CONFIG_NO_HZ) /** * hrtimer_get_next_event - get the time until next expiry event * * Returns the delta to the next expiry event or KTIME_MAX if no timer * is pending. */ ktime_t hrtimer_get_next_event(void) { struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases); struct hrtimer_clock_base *base = cpu_base->clock_base; ktime_t delta, mindelta = { .tv64 = KTIME_MAX }; unsigned long flags; int i; spin_lock_irqsave(&cpu_base->lock, flags); if (!hrtimer_hres_active()) { for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++, base++) { struct hrtimer *timer; if (!base->first) continue; timer = rb_entry(base->first, struct hrtimer, node); delta.tv64 = timer->expires.tv64; delta = ktime_sub(delta, base->get_time()); if (delta.tv64 < mindelta.tv64) mindelta.tv64 = delta.tv64; } } spin_unlock_irqrestore(&cpu_base->lock, flags); if (mindelta.tv64 < 0) mindelta.tv64 = 0; return mindelta; } #endif /** * hrtimer_init - initialize a timer to the given clock * @timer: the timer to be initialized * @clock_id: the clock to be used * @mode: timer mode abs/rel */ void hrtimer_init(struct hrtimer *timer, clockid_t clock_id, enum hrtimer_mode mode) { struct hrtimer_cpu_base *cpu_base; memset(timer, 0, sizeof(struct hrtimer)); cpu_base = &__raw_get_cpu_var(hrtimer_bases); if (clock_id == CLOCK_REALTIME && mode != HRTIMER_MODE_ABS) clock_id = CLOCK_MONOTONIC; timer->base = &cpu_base->clock_base[clock_id]; INIT_LIST_HEAD(&timer->cb_entry); hrtimer_init_timer_hres(timer); #ifdef CONFIG_TIMER_STATS timer->start_site = NULL; timer->start_pid = -1; memset(timer->start_comm, 0, TASK_COMM_LEN); #endif } EXPORT_SYMBOL_GPL(hrtimer_init); /** * hrtimer_get_res - get the timer resolution for a clock * @which_clock: which clock to query * @tp: pointer to timespec variable to store the resolution * * Store the resolution of the clock selected by @which_clock in the * variable pointed to by @tp. */ int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp) { struct hrtimer_cpu_base *cpu_base; cpu_base = &__raw_get_cpu_var(hrtimer_bases); *tp = ktime_to_timespec(cpu_base->clock_base[which_clock].resolution); return 0; } EXPORT_SYMBOL_GPL(hrtimer_get_res); static void run_hrtimer_pending(struct hrtimer_cpu_base *cpu_base) { spin_lock_irq(&cpu_base->lock); while (!list_empty(&cpu_base->cb_pending)) { enum hrtimer_restart (*fn)(struct hrtimer *); struct hrtimer *timer; int restart; timer = list_entry(cpu_base->cb_pending.next, struct hrtimer, cb_entry); timer_stats_account_hrtimer(timer); fn = timer->function; __remove_hrtimer(timer, timer->base, HRTIMER_STATE_CALLBACK, 0); spin_unlock_irq(&cpu_base->lock); restart = fn(timer); spin_lock_irq(&cpu_base->lock); timer->state &= ~HRTIMER_STATE_CALLBACK; if (restart == HRTIMER_RESTART) { BUG_ON(hrtimer_active(timer)); /* * Enqueue the timer, allow reprogramming of the event * device */ enqueue_hrtimer(timer, timer->base, 1); } else if (hrtimer_active(timer)) { /* * If the timer was rearmed on another CPU, reprogram * the event device. */ if (timer->base->first == &timer->node) hrtimer_reprogram(timer, timer->base); } } spin_unlock_irq(&cpu_base->lock); } static void __run_hrtimer(struct hrtimer *timer) { struct hrtimer_clock_base *base = timer->base; struct hrtimer_cpu_base *cpu_base = base->cpu_base; enum hrtimer_restart (*fn)(struct hrtimer *); int restart; __remove_hrtimer(timer, base, HRTIMER_STATE_CALLBACK, 0); timer_stats_account_hrtimer(timer); fn = timer->function; if (timer->cb_mode == HRTIMER_CB_IRQSAFE_NO_SOFTIRQ) { /* * Used for scheduler timers, avoid lock inversion with * rq->lock and tasklist_lock. * * These timers are required to deal with enqueue expiry * themselves and are not allowed to migrate. */ spin_unlock(&cpu_base->lock); restart = fn(timer); spin_lock(&cpu_base->lock); } else restart = fn(timer); /* * Note: We clear the CALLBACK bit after enqueue_hrtimer to avoid * reprogramming of the event hardware. This happens at the end of this * function anyway. */ if (restart != HRTIMER_NORESTART) { BUG_ON(timer->state != HRTIMER_STATE_CALLBACK); enqueue_hrtimer(timer, base, 0); } timer->state &= ~HRTIMER_STATE_CALLBACK; } #ifdef CONFIG_HIGH_RES_TIMERS /* * High resolution timer interrupt * Called with interrupts disabled */ void hrtimer_interrupt(struct clock_event_device *dev) { struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases); struct hrtimer_clock_base *base; ktime_t expires_next, now; int i, raise = 0; BUG_ON(!cpu_base->hres_active); cpu_base->nr_events++; dev->next_event.tv64 = KTIME_MAX; retry: now = ktime_get(); expires_next.tv64 = KTIME_MAX; base = cpu_base->clock_base; for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) { ktime_t basenow; struct rb_node *node; spin_lock(&cpu_base->lock); basenow = ktime_add(now, base->offset); while ((node = base->first)) { struct hrtimer *timer; timer = rb_entry(node, struct hrtimer, node); if (basenow.tv64 < timer->expires.tv64) { ktime_t expires; expires = ktime_sub(timer->expires, base->offset); if (expires.tv64 < expires_next.tv64) expires_next = expires; break; } /* Move softirq callbacks to the pending list */ if (timer->cb_mode == HRTIMER_CB_SOFTIRQ) { __remove_hrtimer(timer, base, HRTIMER_STATE_PENDING, 0); list_add_tail(&timer->cb_entry, &base->cpu_base->cb_pending); raise = 1; continue; } __run_hrtimer(timer); } spin_unlock(&cpu_base->lock); base++; } cpu_base->expires_next = expires_next; /* Reprogramming necessary ? */ if (expires_next.tv64 != KTIME_MAX) { if (tick_program_event(expires_next, 0)) goto retry; } /* Raise softirq ? */ if (raise) raise_softirq(HRTIMER_SOFTIRQ); } static void run_hrtimer_softirq(struct softirq_action *h) { run_hrtimer_pending(&__get_cpu_var(hrtimer_bases)); } #endif /* CONFIG_HIGH_RES_TIMERS */ /* * Called from timer softirq every jiffy, expire hrtimers: * * For HRT its the fall back code to run the softirq in the timer * softirq context in case the hrtimer initialization failed or has * not been done yet. */ void hrtimer_run_pending(void) { struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases); if (hrtimer_hres_active()) return; /* * This _is_ ugly: We have to check in the softirq context, * whether we can switch to highres and / or nohz mode. The * clocksource switch happens in the timer interrupt with * xtime_lock held. Notification from there only sets the * check bit in the tick_oneshot code, otherwise we might * deadlock vs. xtime_lock. */ if (tick_check_oneshot_change(!hrtimer_is_hres_enabled())) hrtimer_switch_to_hres(); run_hrtimer_pending(cpu_base); } /* * Called from hardirq context every jiffy */ static inline void run_hrtimer_queue(struct hrtimer_cpu_base *cpu_base, int index) { struct rb_node *node; struct hrtimer_clock_base *base = &cpu_base->clock_base[index]; if (!base->first) return; if (base->get_softirq_time) base->softirq_time = base->get_softirq_time(); spin_lock(&cpu_base->lock); while ((node = base->first)) { struct hrtimer *timer; timer = rb_entry(node, struct hrtimer, node); if (base->softirq_time.tv64 <= timer->expires.tv64) break; if (timer->cb_mode == HRTIMER_CB_SOFTIRQ) { __remove_hrtimer(timer, base, HRTIMER_STATE_PENDING, 0); list_add_tail(&timer->cb_entry, &base->cpu_base->cb_pending); continue; } __run_hrtimer(timer); } spin_unlock(&cpu_base->lock); } void hrtimer_run_queues(void) { struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases); int i; if (hrtimer_hres_active()) return; hrtimer_get_softirq_time(cpu_base); for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) run_hrtimer_queue(cpu_base, i); } /* * Sleep related functions: */ static enum hrtimer_restart hrtimer_wakeup(struct hrtimer *timer) { struct hrtimer_sleeper *t = container_of(timer, struct hrtimer_sleeper, timer); struct task_struct *task = t->task; t->task = NULL; if (task) wake_up_process(task); return HRTIMER_NORESTART; } void hrtimer_init_sleeper(struct hrtimer_sleeper *sl, struct task_struct *task) { sl->timer.function = hrtimer_wakeup; sl->task = task; #ifdef CONFIG_HIGH_RES_TIMERS sl->timer.cb_mode = HRTIMER_CB_IRQSAFE_NO_SOFTIRQ; #endif } static int __sched do_nanosleep(struct hrtimer_sleeper *t, enum hrtimer_mode mode) { hrtimer_init_sleeper(t, current); do { set_current_state(TASK_INTERRUPTIBLE); hrtimer_start(&t->timer, t->timer.expires, mode); if (!hrtimer_active(&t->timer)) t->task = NULL; if (likely(t->task)) schedule(); hrtimer_cancel(&t->timer); mode = HRTIMER_MODE_ABS; } while (t->task && !signal_pending(current)); return t->task == NULL; } long __sched hrtimer_nanosleep_restart(struct restart_block *restart) { struct hrtimer_sleeper t; struct timespec *rmtp; ktime_t time; restart->fn = do_no_restart_syscall; hrtimer_init(&t.timer, restart->arg0, HRTIMER_MODE_ABS); t.timer.expires.tv64 = ((u64)restart->arg3 << 32) | (u64) restart->arg2; if (do_nanosleep(&t, HRTIMER_MODE_ABS)) return 0; rmtp = (struct timespec *)restart->arg1; if (rmtp) { time = ktime_sub(t.timer.expires, t.timer.base->get_time()); if (time.tv64 <= 0) return 0; *rmtp = ktime_to_timespec(time); } restart->fn = hrtimer_nanosleep_restart; /* The other values in restart are already filled in */ return -ERESTART_RESTARTBLOCK; } long hrtimer_nanosleep(struct timespec *rqtp, struct timespec *rmtp, const enum hrtimer_mode mode, const clockid_t clockid) { struct restart_block *restart; struct hrtimer_sleeper t; ktime_t rem; hrtimer_init(&t.timer, clockid, mode); t.timer.expires = timespec_to_ktime(*rqtp); if (do_nanosleep(&t, mode)) return 0; /* Absolute timers do not update the rmtp value and restart: */ if (mode == HRTIMER_MODE_ABS) return -ERESTARTNOHAND; if (rmtp) { rem = ktime_sub(t.timer.expires, t.timer.base->get_time()); if (rem.tv64 <= 0) return 0; *rmtp = ktime_to_timespec(rem); } restart = ¤t_thread_info()->restart_block; restart->fn = hrtimer_nanosleep_restart; restart->arg0 = (unsigned long) t.timer.base->index; restart->arg1 = (unsigned long) rmtp; restart->arg2 = t.timer.expires.tv64 & 0xFFFFFFFF; restart->arg3 = t.timer.expires.tv64 >> 32; return -ERESTART_RESTARTBLOCK; } asmlinkage long sys_nanosleep(struct timespec __user *rqtp, struct timespec __user *rmtp) { struct timespec tu, rmt; int ret; if (copy_from_user(&tu, rqtp, sizeof(tu))) return -EFAULT; if (!timespec_valid(&tu)) return -EINVAL; ret = hrtimer_nanosleep(&tu, rmtp ? &rmt : NULL, HRTIMER_MODE_REL, CLOCK_MONOTONIC); if (ret && rmtp) { if (copy_to_user(rmtp, &rmt, sizeof(*rmtp))) return -EFAULT; } return ret; } /* * Functions related to boot-time initialization: */ static void __cpuinit init_hrtimers_cpu(int cpu) { struct hrtimer_cpu_base *cpu_base = &per_cpu(hrtimer_bases, cpu); int i; spin_lock_init(&cpu_base->lock); lockdep_set_class(&cpu_base->lock, &cpu_base->lock_key); for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) cpu_base->clock_base[i].cpu_base = cpu_base; INIT_LIST_HEAD(&cpu_base->cb_pending); hrtimer_init_hres(cpu_base); } #ifdef CONFIG_HOTPLUG_CPU static void migrate_hrtimer_list(struct hrtimer_clock_base *old_base, struct hrtimer_clock_base *new_base) { struct hrtimer *timer; struct rb_node *node; while ((node = rb_first(&old_base->active))) { timer = rb_entry(node, struct hrtimer, node); BUG_ON(hrtimer_callback_running(timer)); __remove_hrtimer(timer, old_base, HRTIMER_STATE_INACTIVE, 0); timer->base = new_base; /* * Enqueue the timer. Allow reprogramming of the event device */ enqueue_hrtimer(timer, new_base, 1); } } static void migrate_hrtimers(int cpu) { struct hrtimer_cpu_base *old_base, *new_base; int i; BUG_ON(cpu_online(cpu)); old_base = &per_cpu(hrtimer_bases, cpu); new_base = &get_cpu_var(hrtimer_bases); tick_cancel_sched_timer(cpu); local_irq_disable(); double_spin_lock(&new_base->lock, &old_base->lock, smp_processor_id() < cpu); for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) { migrate_hrtimer_list(&old_base->clock_base[i], &new_base->clock_base[i]); } double_spin_unlock(&new_base->lock, &old_base->lock, smp_processor_id() < cpu); local_irq_enable(); put_cpu_var(hrtimer_bases); } #endif /* CONFIG_HOTPLUG_CPU */ static int __cpuinit hrtimer_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu) { unsigned int cpu = (long)hcpu; switch (action) { case CPU_UP_PREPARE: case CPU_UP_PREPARE_FROZEN: init_hrtimers_cpu(cpu); break; #ifdef CONFIG_HOTPLUG_CPU case CPU_DEAD: case CPU_DEAD_FROZEN: clockevents_notify(CLOCK_EVT_NOTIFY_CPU_DEAD, &cpu); migrate_hrtimers(cpu); break; #endif default: break; } return NOTIFY_OK; } static struct notifier_block __cpuinitdata hrtimers_nb = { .notifier_call = hrtimer_cpu_notify, }; void __init hrtimers_init(void) { hrtimer_cpu_notify(&hrtimers_nb, (unsigned long)CPU_UP_PREPARE, (void *)(long)smp_processor_id()); register_cpu_notifier(&hrtimers_nb); #ifdef CONFIG_HIGH_RES_TIMERS open_softirq(HRTIMER_SOFTIRQ, run_hrtimer_softirq, NULL); #endif }