/* * 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/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 <linux/debugobjects.h> #include <linux/sched.h> #include <linux/timer.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); } /* * 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(); } } /* * Get the preferred target CPU for NOHZ */ static int hrtimer_get_target(int this_cpu, int pinned) { #ifdef CONFIG_NO_HZ if (!pinned && get_sysctl_timer_migration() && idle_cpu(this_cpu)) { int preferred_cpu = get_nohz_load_balancer(); if (preferred_cpu >= 0) return preferred_cpu; } #endif return this_cpu; } /* * With HIGHRES=y we do not migrate the timer when it is expiring * before the next event on the target cpu because we cannot reprogram * the target cpu hardware and we would cause it to fire late. * * Called with cpu_base->lock of target cpu held. */ static int hrtimer_check_target(struct hrtimer *timer, struct hrtimer_clock_base *new_base) { #ifdef CONFIG_HIGH_RES_TIMERS ktime_t expires; if (!new_base->cpu_base->hres_active) return 0; expires = ktime_sub(hrtimer_get_expires(timer), new_base->offset); return expires.tv64 <= new_base->cpu_base->expires_next.tv64; #else return 0; #endif } /* * 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, int pinned) { struct hrtimer_clock_base *new_base; struct hrtimer_cpu_base *new_cpu_base; int this_cpu = smp_processor_id(); int cpu = hrtimer_get_target(this_cpu, pinned); again: new_cpu_base = &per_cpu(hrtimer_bases, cpu); new_base = &new_cpu_base->clock_base[base->index]; if (base != new_base) { /* * We are trying to move timer to new_base. * 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); if (cpu != this_cpu && hrtimer_check_target(timer, new_base)) { cpu = this_cpu; spin_unlock(&new_base->cpu_base->lock); spin_lock(&base->cpu_base->lock); timer->base = base; goto again; } 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, p) (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 */ u64 ktime_divns(const ktime_t kt, s64 div) { u64 dclc; int sft = 0; dclc = ktime_to_ns(kt); /* Make sure the divisor is less than 2^32: */ while (div >> 32) { sft++; div >>= 1; } dclc >>= sft; do_div(dclc, (unsigned long) div); return dclc; } #endif /* BITS_PER_LONG >= 64 */ /* * Add two ktime values and do a safety check for overflow: */ ktime_t ktime_add_safe(const ktime_t lhs, const ktime_t rhs) { ktime_t res = ktime_add(lhs, rhs); /* * We use KTIME_SEC_MAX here, the maximum timeout which we can * return to user space in a timespec: */ if (res.tv64 < 0 || res.tv64 < lhs.tv64 || res.tv64 < rhs.tv64) res = ktime_set(KTIME_SEC_MAX, 0); return res; } EXPORT_SYMBOL_GPL(ktime_add_safe); #ifdef CONFIG_DEBUG_OBJECTS_TIMERS static struct debug_obj_descr hrtimer_debug_descr; /* * fixup_init is called when: * - an active object is initialized */ static int hrtimer_fixup_init(void *addr, enum debug_obj_state state) { struct hrtimer *timer = addr; switch (state) { case ODEBUG_STATE_ACTIVE: hrtimer_cancel(timer); debug_object_init(timer, &hrtimer_debug_descr); return 1; default: return 0; } } /* * fixup_activate is called when: * - an active object is activated * - an unknown object is activated (might be a statically initialized object) */ static int hrtimer_fixup_activate(void *addr, enum debug_obj_state state) { switch (state) { case ODEBUG_STATE_NOTAVAILABLE: WARN_ON_ONCE(1); return 0; case ODEBUG_STATE_ACTIVE: WARN_ON(1); default: return 0; } } /* * fixup_free is called when: * - an active object is freed */ static int hrtimer_fixup_free(void *addr, enum debug_obj_state state) { struct hrtimer *timer = addr; switch (state) { case ODEBUG_STATE_ACTIVE: hrtimer_cancel(timer); debug_object_free(timer, &hrtimer_debug_descr); return 1; default: return 0; } } static struct debug_obj_descr hrtimer_debug_descr = { .name = "hrtimer", .fixup_init = hrtimer_fixup_init, .fixup_activate = hrtimer_fixup_activate, .fixup_free = hrtimer_fixup_free, }; static inline void debug_hrtimer_init(struct hrtimer *timer) { debug_object_init(timer, &hrtimer_debug_descr); } static inline void debug_hrtimer_activate(struct hrtimer *timer) { debug_object_activate(timer, &hrtimer_debug_descr); } static inline void debug_hrtimer_deactivate(struct hrtimer *timer) { debug_object_deactivate(timer, &hrtimer_debug_descr); } static inline void debug_hrtimer_free(struct hrtimer *timer) { debug_object_free(timer, &hrtimer_debug_descr); } static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id, enum hrtimer_mode mode); void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t clock_id, enum hrtimer_mode mode) { debug_object_init_on_stack(timer, &hrtimer_debug_descr); __hrtimer_init(timer, clock_id, mode); } void destroy_hrtimer_on_stack(struct hrtimer *timer) { debug_object_free(timer, &hrtimer_debug_descr); } #else static inline void debug_hrtimer_init(struct hrtimer *timer) { } static inline void debug_hrtimer_activate(struct hrtimer *timer) { } static inline void debug_hrtimer_deactivate(struct hrtimer *timer) { } #endif /* 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(hrtimer_get_expires(timer), base->offset); /* * clock_was_set() has changed base->offset so the * result might be negative. Fix it up to prevent a * false positive in clockevents_program_event() */ if (expires.tv64 < 0) expires.tv64 = 0; 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(hrtimer_get_expires(timer), base->offset); int res; WARN_ON_ONCE(hrtimer_get_expires_tv64(timer) < 0); /* * 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; /* * CLOCK_REALTIME timer might be requested with an absolute * expiry time which is less than base->offset. Nothing wrong * about that, just avoid to call into the tick code, which * has now objections against negative expiry values. */ if (expires.tv64 < 0) return -ETIME; 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, 1); } /* * During resume we might have to reprogram the high resolution timer * interrupt (on the local CPU): */ void hres_timers_resume(void) { WARN_ONCE(!irqs_disabled(), KERN_INFO "hres_timers_resume() called with IRQs enabled!"); 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, int wakeup) { if (base->cpu_base->hres_active && hrtimer_reprogram(timer, base)) { if (wakeup) { spin_unlock(&base->cpu_base->lock); raise_softirq_irqoff(HRTIMER_SOFTIRQ); spin_lock(&base->cpu_base->lock); } else __raise_softirq_irqoff(HRTIMER_SOFTIRQ); return 1; } 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, int wakeup) { return 0; } static inline void hrtimer_init_hres(struct hrtimer_cpu_base *base) { } static inline void hrtimer_init_timer_hres(struct hrtimer *timer) { } #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. */ u64 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval) { u64 orun = 1; ktime_t delta; delta = ktime_sub(now, hrtimer_get_expires(timer)); 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); hrtimer_add_expires_ns(timer, incr * orun); if (hrtimer_get_expires_tv64(timer) > now.tv64) return orun; /* * This (and the ktime_add() below) is the * correction for exact: */ orun++; } hrtimer_add_expires(timer, interval); 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. * * Returns 1 when the new timer is the leftmost timer in the tree. */ static int enqueue_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base) { struct rb_node **link = &base->active.rb_node; struct rb_node *parent = NULL; struct hrtimer *entry; int leftmost = 1; debug_hrtimer_activate(timer); /* * 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 (hrtimer_get_expires_tv64(timer) < hrtimer_get_expires_tv64(entry)) { 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) 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; return leftmost; } /* * __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) { if (timer->state & HRTIMER_STATE_ENQUEUED) { /* * 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. */ debug_hrtimer_deactivate(timer); 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; } int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim, unsigned long delta_ns, const enum hrtimer_mode mode, int wakeup) { struct hrtimer_clock_base *base, *new_base; unsigned long flags; int ret, leftmost; 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, mode & HRTIMER_MODE_PINNED); if (mode & HRTIMER_MODE_REL) { tim = ktime_add_safe(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_safe(tim, base->resolution); #endif } hrtimer_set_expires_range_ns(timer, tim, delta_ns); timer_stats_hrtimer_set_start_info(timer); leftmost = enqueue_hrtimer(timer, new_base); /* * Only allow reprogramming if the new base is on this CPU. * (it might still be on another CPU if the timer was pending) * * XXX send_remote_softirq() ? */ if (leftmost && new_base->cpu_base == &__get_cpu_var(hrtimer_bases)) hrtimer_enqueue_reprogram(timer, new_base, wakeup); unlock_hrtimer_base(timer, &flags); return ret; } /** * hrtimer_start_range_ns - (re)start an hrtimer on the current CPU * @timer: the timer to be added * @tim: expiry time * @delta_ns: "slack" range for the timer * @mode: expiry mode: absolute (HRTIMER_ABS) or relative (HRTIMER_REL) * * Returns: * 0 on success * 1 when the timer was active */ int hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim, unsigned long delta_ns, const enum hrtimer_mode mode) { return __hrtimer_start_range_ns(timer, tim, delta_ns, mode, 1); } EXPORT_SYMBOL_GPL(hrtimer_start_range_ns); /** * hrtimer_start - (re)start an hrtimer 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) { return __hrtimer_start_range_ns(timer, tim, 0, mode, 1); } 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 = hrtimer_expires_remaining(timer); unlock_hrtimer_base(timer, &flags); return rem; } EXPORT_SYMBOL_GPL(hrtimer_get_remaining); #ifdef 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 = hrtimer_get_expires_tv64(timer); 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 static 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 } /** * 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) { debug_hrtimer_init(timer); __hrtimer_init(timer, clock_id, mode); } 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(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; WARN_ON(!irqs_disabled()); debug_hrtimer_deactivate(timer); __remove_hrtimer(timer, base, HRTIMER_STATE_CALLBACK, 0); timer_stats_account_hrtimer(timer); fn = timer->function; /* * Because we run timers from hardirq context, there is no chance * they get migrated to another cpu, therefore its safe to unlock * the timer base. */ spin_unlock(&cpu_base->lock); restart = fn(timer); spin_lock(&cpu_base->lock); /* * Note: We clear the CALLBACK bit after enqueue_hrtimer and * we do not reprogramm the event hardware. Happens either in * hrtimer_start_range_ns() or in hrtimer_interrupt() */ if (restart != HRTIMER_NORESTART) { BUG_ON(timer->state != HRTIMER_STATE_CALLBACK); enqueue_hrtimer(timer, base); } timer->state &= ~HRTIMER_STATE_CALLBACK; } #ifdef CONFIG_HIGH_RES_TIMERS static int force_clock_reprogram; /* * After 5 iteration's attempts, we consider that hrtimer_interrupt() * is hanging, which could happen with something that slows the interrupt * such as the tracing. Then we force the clock reprogramming for each future * hrtimer interrupts to avoid infinite loops and use the min_delta_ns * threshold that we will overwrite. * The next tick event will be scheduled to 3 times we currently spend on * hrtimer_interrupt(). This gives a good compromise, the cpus will spend * 1/4 of their time to process the hrtimer interrupts. This is enough to * let it running without serious starvation. */ static inline void hrtimer_interrupt_hanging(struct clock_event_device *dev, ktime_t try_time) { force_clock_reprogram = 1; dev->min_delta_ns = (unsigned long)try_time.tv64 * 3; printk(KERN_WARNING "hrtimer: interrupt too slow, " "forcing clock min delta to %lu ns\n", dev->min_delta_ns); } /* * 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 nr_retries = 0; int i; BUG_ON(!cpu_base->hres_active); cpu_base->nr_events++; dev->next_event.tv64 = KTIME_MAX; retry: /* 5 retries is enough to notice a hang */ if (!(++nr_retries % 5)) hrtimer_interrupt_hanging(dev, ktime_sub(ktime_get(), now)); now = ktime_get(); expires_next.tv64 = KTIME_MAX; spin_lock(&cpu_base->lock); /* * We set expires_next to KTIME_MAX here with cpu_base->lock * held to prevent that a timer is enqueued in our queue via * the migration code. This does not affect enqueueing of * timers which run their callback and need to be requeued on * this CPU. */ cpu_base->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; basenow = ktime_add(now, base->offset); while ((node = base->first)) { struct hrtimer *timer; timer = rb_entry(node, struct hrtimer, node); /* * The immediate goal for using the softexpires is * minimizing wakeups, not running timers at the * earliest interrupt after their soft expiration. * This allows us to avoid using a Priority Search * Tree, which can answer a stabbing querry for * overlapping intervals and instead use the simple * BST we already have. * We don't add extra wakeups by delaying timers that * are right-of a not yet expired timer, because that * timer will have to trigger a wakeup anyway. */ if (basenow.tv64 < hrtimer_get_softexpires_tv64(timer)) { ktime_t expires; expires = ktime_sub(hrtimer_get_expires(timer), base->offset); if (expires.tv64 < expires_next.tv64) expires_next = expires; break; } __run_hrtimer(timer); } base++; } /* * Store the new expiry value so the migration code can verify * against it. */ cpu_base->expires_next = expires_next; spin_unlock(&cpu_base->lock); /* Reprogramming necessary ? */ if (expires_next.tv64 != KTIME_MAX) { if (tick_program_event(expires_next, force_clock_reprogram)) goto retry; } } /* * local version of hrtimer_peek_ahead_timers() called with interrupts * disabled. */ static void __hrtimer_peek_ahead_timers(void) { struct tick_device *td; if (!hrtimer_hres_active()) return; td = &__get_cpu_var(tick_cpu_device); if (td && td->evtdev) hrtimer_interrupt(td->evtdev); } /** * hrtimer_peek_ahead_timers -- run soft-expired timers now * * hrtimer_peek_ahead_timers will peek at the timer queue of * the current cpu and check if there are any timers for which * the soft expires time has passed. If any such timers exist, * they are run immediately and then removed from the timer queue. * */ void hrtimer_peek_ahead_timers(void) { unsigned long flags; local_irq_save(flags); __hrtimer_peek_ahead_timers(); local_irq_restore(flags); } static void run_hrtimer_softirq(struct softirq_action *h) { hrtimer_peek_ahead_timers(); } #else /* CONFIG_HIGH_RES_TIMERS */ static inline void __hrtimer_peek_ahead_timers(void) { } #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) { 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(); } /* * Called from hardirq context every jiffy */ void hrtimer_run_queues(void) { struct rb_node *node; struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases); struct hrtimer_clock_base *base; int index, gettime = 1; if (hrtimer_hres_active()) return; for (index = 0; index < HRTIMER_MAX_CLOCK_BASES; index++) { base = &cpu_base->clock_base[index]; if (!base->first) continue; if (gettime) { hrtimer_get_softirq_time(cpu_base); gettime = 0; } spin_lock(&cpu_base->lock); while ((node = base->first)) { struct hrtimer *timer; timer = rb_entry(node, struct hrtimer, node); if (base->softirq_time.tv64 <= hrtimer_get_expires_tv64(timer)) break; __run_hrtimer(timer); } spin_unlock(&cpu_base->lock); } } /* * 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; } 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_expires(&t->timer, 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)); __set_current_state(TASK_RUNNING); return t->task == NULL; } static int update_rmtp(struct hrtimer *timer, struct timespec __user *rmtp) { struct timespec rmt; ktime_t rem; rem = hrtimer_expires_remaining(timer); if (rem.tv64 <= 0) return 0; rmt = ktime_to_timespec(rem); if (copy_to_user(rmtp, &rmt, sizeof(*rmtp))) return -EFAULT; return 1; } long __sched hrtimer_nanosleep_restart(struct restart_block *restart) { struct hrtimer_sleeper t; struct timespec __user *rmtp; int ret = 0; hrtimer_init_on_stack(&t.timer, restart->nanosleep.index, HRTIMER_MODE_ABS); hrtimer_set_expires_tv64(&t.timer, restart->nanosleep.expires); if (do_nanosleep(&t, HRTIMER_MODE_ABS)) goto out; rmtp = restart->nanosleep.rmtp; if (rmtp) { ret = update_rmtp(&t.timer, rmtp); if (ret <= 0) goto out; } /* The other values in restart are already filled in */ ret = -ERESTART_RESTARTBLOCK; out: destroy_hrtimer_on_stack(&t.timer); return ret; } long hrtimer_nanosleep(struct timespec *rqtp, struct timespec __user *rmtp, const enum hrtimer_mode mode, const clockid_t clockid) { struct restart_block *restart; struct hrtimer_sleeper t; int ret = 0; unsigned long slack; slack = current->timer_slack_ns; if (rt_task(current)) slack = 0; hrtimer_init_on_stack(&t.timer, clockid, mode); hrtimer_set_expires_range_ns(&t.timer, timespec_to_ktime(*rqtp), slack); if (do_nanosleep(&t, mode)) goto out; /* Absolute timers do not update the rmtp value and restart: */ if (mode == HRTIMER_MODE_ABS) { ret = -ERESTARTNOHAND; goto out; } if (rmtp) { ret = update_rmtp(&t.timer, rmtp); if (ret <= 0) goto out; } restart = ¤t_thread_info()->restart_block; restart->fn = hrtimer_nanosleep_restart; restart->nanosleep.index = t.timer.base->index; restart->nanosleep.rmtp = rmtp; restart->nanosleep.expires = hrtimer_get_expires_tv64(&t.timer); ret = -ERESTART_RESTARTBLOCK; out: destroy_hrtimer_on_stack(&t.timer); return ret; } SYSCALL_DEFINE2(nanosleep, struct timespec __user *, rqtp, struct timespec __user *, rmtp) { struct timespec tu; if (copy_from_user(&tu, rqtp, sizeof(tu))) return -EFAULT; if (!timespec_valid(&tu)) return -EINVAL; return hrtimer_nanosleep(&tu, rmtp, HRTIMER_MODE_REL, CLOCK_MONOTONIC); } /* * 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); for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) cpu_base->clock_base[i].cpu_base = cpu_base; 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)); debug_hrtimer_deactivate(timer); /* * Mark it as STATE_MIGRATE not INACTIVE otherwise the * timer could be seen as !active and just vanish away * under us on another CPU */ __remove_hrtimer(timer, old_base, HRTIMER_STATE_MIGRATE, 0); timer->base = new_base; /* * Enqueue the timers on the new cpu. This does not * reprogram the event device in case the timer * expires before the earliest on this CPU, but we run * hrtimer_interrupt after we migrated everything to * sort out already expired timers and reprogram the * event device. */ enqueue_hrtimer(timer, new_base); /* Clear the migration state bit */ timer->state &= ~HRTIMER_STATE_MIGRATE; } } static void migrate_hrtimers(int scpu) { struct hrtimer_cpu_base *old_base, *new_base; int i; BUG_ON(cpu_online(scpu)); tick_cancel_sched_timer(scpu); local_irq_disable(); old_base = &per_cpu(hrtimer_bases, scpu); new_base = &__get_cpu_var(hrtimer_bases); /* * The caller is globally serialized and nobody else * takes two locks at once, deadlock is not possible. */ spin_lock(&new_base->lock); spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING); for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) { migrate_hrtimer_list(&old_base->clock_base[i], &new_base->clock_base[i]); } spin_unlock(&old_base->lock); spin_unlock(&new_base->lock); /* Check, if we got expired work to do */ __hrtimer_peek_ahead_timers(); local_irq_enable(); } #endif /* CONFIG_HOTPLUG_CPU */ static int __cpuinit hrtimer_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu) { int scpu = (long)hcpu; switch (action) { case CPU_UP_PREPARE: case CPU_UP_PREPARE_FROZEN: init_hrtimers_cpu(scpu); break; #ifdef CONFIG_HOTPLUG_CPU case CPU_DYING: case CPU_DYING_FROZEN: clockevents_notify(CLOCK_EVT_NOTIFY_CPU_DYING, &scpu); break; case CPU_DEAD: case CPU_DEAD_FROZEN: { clockevents_notify(CLOCK_EVT_NOTIFY_CPU_DEAD, &scpu); migrate_hrtimers(scpu); 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); #endif } /** * schedule_hrtimeout_range - sleep until timeout * @expires: timeout value (ktime_t) * @delta: slack in expires timeout (ktime_t) * @mode: timer mode, HRTIMER_MODE_ABS or HRTIMER_MODE_REL * * Make the current task sleep until the given expiry time has * elapsed. The routine will return immediately unless * the current task state has been set (see set_current_state()). * * The @delta argument gives the kernel the freedom to schedule the * actual wakeup to a time that is both power and performance friendly. * The kernel give the normal best effort behavior for "@expires+@delta", * but may decide to fire the timer earlier, but no earlier than @expires. * * You can set the task state as follows - * * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to * pass before the routine returns. * * %TASK_INTERRUPTIBLE - the routine may return early if a signal is * delivered to the current task. * * The current task state is guaranteed to be TASK_RUNNING when this * routine returns. * * Returns 0 when the timer has expired otherwise -EINTR */ int __sched schedule_hrtimeout_range(ktime_t *expires, unsigned long delta, const enum hrtimer_mode mode) { struct hrtimer_sleeper t; /* * Optimize when a zero timeout value is given. It does not * matter whether this is an absolute or a relative time. */ if (expires && !expires->tv64) { __set_current_state(TASK_RUNNING); return 0; } /* * A NULL parameter means "inifinte" */ if (!expires) { schedule(); __set_current_state(TASK_RUNNING); return -EINTR; } hrtimer_init_on_stack(&t.timer, CLOCK_MONOTONIC, mode); hrtimer_set_expires_range_ns(&t.timer, *expires, delta); hrtimer_init_sleeper(&t, current); hrtimer_start_expires(&t.timer, mode); if (!hrtimer_active(&t.timer)) t.task = NULL; if (likely(t.task)) schedule(); hrtimer_cancel(&t.timer); destroy_hrtimer_on_stack(&t.timer); __set_current_state(TASK_RUNNING); return !t.task ? 0 : -EINTR; } EXPORT_SYMBOL_GPL(schedule_hrtimeout_range); /** * schedule_hrtimeout - sleep until timeout * @expires: timeout value (ktime_t) * @mode: timer mode, HRTIMER_MODE_ABS or HRTIMER_MODE_REL * * Make the current task sleep until the given expiry time has * 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 time is guaranteed to * pass before the routine returns. * * %TASK_INTERRUPTIBLE - the routine may return early if a signal is * delivered to the current task. * * The current task state is guaranteed to be TASK_RUNNING when this * routine returns. * * Returns 0 when the timer has expired otherwise -EINTR */ int __sched schedule_hrtimeout(ktime_t *expires, const enum hrtimer_mode mode) { return schedule_hrtimeout_range(expires, 0, mode); } EXPORT_SYMBOL_GPL(schedule_hrtimeout);