*/
#include <linux/cpu.h>
-#include <linux/irq.h>
#include <linux/module.h>
#include <linux/percpu.h>
#include <linux/hrtimer.h>
static inline void debug_hrtimer_deactivate(struct hrtimer *timer) { }
#endif
-/*
- * 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
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;
}
*/
void hres_timers_resume(void)
{
- /* Retrigger the CPU local events: */
+ WARN_ONCE(!irqs_disabled(),
+ KERN_INFO "hres_timers_resume() called with IRQs enabled!");
+
retrigger_next_event(NULL);
}
{
}
+
/*
* 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
* 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)
+ 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);
- /* Timer is expired, act upon the callback mode */
- switch(timer->cb_mode) {
- case HRTIMER_CB_IRQSAFE_NO_RESTART:
- debug_hrtimer_deactivate(timer);
- /*
- * 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.
- */
- debug_hrtimer_deactivate(timer);
- 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;
- return 1;
- default:
- BUG();
- }
+ return 1;
}
+
return 0;
}
return 1;
}
-static inline void hrtimer_raise_softirq(void)
-{
- raise_softirq(HRTIMER_SOFTIRQ);
-}
-
#else
static inline int hrtimer_hres_active(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)
+ 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) { }
-static inline int hrtimer_reprogram(struct hrtimer *timer,
- struct hrtimer_clock_base *base)
-{
- return 0;
-}
-static inline void hrtimer_raise_softirq(void) { }
#endif /* CONFIG_HIGH_RES_TIMERS */
*
* 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 void enqueue_hrtimer(struct hrtimer *timer,
- struct hrtimer_clock_base *base, int reprogram)
+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;
* 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;
-
+ if (leftmost)
base->first = &timer->node;
- }
rb_link_node(&timer->node, parent, link);
rb_insert_color(&timer->node, &base->active);
* state of a possibly running callback.
*/
timer->state |= HRTIMER_STATE_ENQUEUED;
+
+ return leftmost;
}
/*
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 {
+ if (timer->state & HRTIMER_STATE_ENQUEUED) {
/*
* Remove the timer from the rbtree and replace the
* first entry pointer if necessary.
return 0;
}
-/**
- * hrtimer_start_range_ns - (re)start an relative timer 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)
+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, raise;
+ int ret, leftmost;
base = lock_hrtimer_base(timer, &flags);
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() ?
*/
- enqueue_hrtimer(timer, new_base,
- new_base->cpu_base == &__get_cpu_var(hrtimer_bases));
-
- /*
- * The timer may be expired and moved to the cb_pending
- * list. We can not raise the softirq with base lock held due
- * to a possible deadlock with runqueue lock.
- */
- raise = timer->state == HRTIMER_STATE_PENDING;
-
- /*
- * We use preempt_disable to prevent this task from migrating after
- * setting up the softirq and raising it. Otherwise, if me migrate
- * we will raise the softirq on the wrong CPU.
- */
- preempt_disable();
+ if (leftmost && new_base->cpu_base == &__get_cpu_var(hrtimer_bases))
+ hrtimer_enqueue_reprogram(timer, new_base, wakeup);
unlock_hrtimer_base(timer, &flags);
- if (raise)
- hrtimer_raise_softirq();
- preempt_enable();
-
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 relative timer on the current CPU
+ * 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)
int
hrtimer_start(struct hrtimer *timer, ktime_t tim, const enum hrtimer_mode mode)
{
- return hrtimer_start_range_ns(timer, tim, 0, mode);
+ return __hrtimer_start_range_ns(timer, tim, 0, mode, 1);
}
EXPORT_SYMBOL_GPL(hrtimer_start);
}
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);
-
- debug_hrtimer_deactivate(timer);
- 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.
- */
- struct hrtimer_clock_base *base = timer->base;
-
- if (base->first == &timer->node &&
- hrtimer_reprogram(timer, base)) {
- /*
- * Timer is expired. Thus move it from tree to
- * pending list again.
- */
- __remove_hrtimer(timer, base,
- HRTIMER_STATE_PENDING, 0);
- list_add_tail(&timer->cb_entry,
- &base->cpu_base->cb_pending);
- }
- }
- }
- spin_unlock_irq(&cpu_base->lock);
-}
-
static void __run_hrtimer(struct hrtimer *timer)
{
struct hrtimer_clock_base *base = timer->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;
- 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.
+ * 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, 0);
+ 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
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;
+ 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;
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);
/* Reprogramming necessary ? */
if (expires_next.tv64 != KTIME_MAX) {
- if (tick_program_event(expires_next, 0))
+ if (tick_program_event(expires_next, force_clock_reprogram))
goto retry;
}
+}
- /* Raise softirq ? */
- if (raise)
- raise_softirq(HRTIMER_SOFTIRQ);
+/*
+ * 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);
}
/**
void hrtimer_peek_ahead_timers(void)
{
unsigned long flags;
- struct tick_device *td;
- struct clock_event_device *dev;
-
- if (!hrtimer_hres_active())
- return;
local_irq_save(flags);
- td = &__get_cpu_var(tick_cpu_device);
- if (!td)
- goto out;
- dev = td->evtdev;
- if (!dev)
- goto out;
- hrtimer_interrupt(dev);
-out:
+ __hrtimer_peek_ahead_timers();
local_irq_restore(flags);
}
static void run_hrtimer_softirq(struct softirq_action *h)
{
- run_hrtimer_pending(&__get_cpu_var(hrtimer_bases));
+ hrtimer_peek_ahead_timers();
}
-#endif /* CONFIG_HIGH_RES_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:
*/
void hrtimer_run_pending(void)
{
- struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
-
if (hrtimer_hres_active())
return;
*/
if (tick_check_oneshot_change(!hrtimer_is_hres_enabled()))
hrtimer_switch_to_hres();
-
- run_hrtimer_pending(cpu_base);
}
/*
if (!base->first)
continue;
- if (base->get_softirq_time)
- base->softirq_time = base->get_softirq_time();
- else if (gettime) {
+ if (gettime) {
hrtimer_get_softirq_time(cpu_base);
gettime = 0;
}
hrtimer_get_expires_tv64(timer))
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);
{
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)
return ret;
}
-asmlinkage long
-sys_nanosleep(struct timespec __user *rqtp, struct timespec __user *rmtp)
+SYSCALL_DEFINE2(nanosleep, struct timespec __user *, rqtp,
+ struct timespec __user *, rmtp)
{
struct timespec tu;
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);
}
timer = rb_entry(node, struct hrtimer, node);
BUG_ON(hrtimer_callback_running(timer));
debug_hrtimer_deactivate(timer);
- __remove_hrtimer(timer, old_base, HRTIMER_STATE_INACTIVE, 0);
+
+ /*
+ * 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 timer. Allow reprogramming of the event device
+ * 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, 1);
+ enqueue_hrtimer(timer, new_base);
+
+ /* Clear the migration state bit */
+ timer->state &= ~HRTIMER_STATE_MIGRATE;
}
}
-static void migrate_hrtimers(int cpu)
+static void migrate_hrtimers(int scpu)
{
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);
+ 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);
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();
- 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;
+ int scpu = (long)hcpu;
switch (action) {
case CPU_UP_PREPARE:
case CPU_UP_PREPARE_FROZEN:
- init_hrtimers_cpu(cpu);
+ 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, &cpu);
- migrate_hrtimers(cpu);
+ {
+ clockevents_notify(CLOCK_EVT_NOTIFY_CPU_DEAD, &scpu);
+ migrate_hrtimers(scpu);
break;
+ }
#endif
default:
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff