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Merge branch 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

Browse source 
* 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  hrtimer: splitout peek ahead functionality, fix
  hrtimer: fixup comments
  hrtimer: fix recursion deadlock by re-introducing the softirq
  hrtimer: simplify hotplug migration
  hrtimer: fix HOTPLUG_CPU=n compile warning
  hrtimer: splitout peek ahead functionality
This commit is contained in:
Linus Torvalds 2009-01-06 17:10:53 -08:00
commit 3610639d1f
2 changed files with 72 additions and 73 deletions
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3
include/linux/interrupt.h
View file

@ -252,7 +252,8 @@ enum
BLOCK_SOFTIRQ, BLOCK_SOFTIRQ,
TASKLET_SOFTIRQ, TASKLET_SOFTIRQ,
SCHED_SOFTIRQ, SCHED_SOFTIRQ,
RCU_SOFTIRQ, /* Preferable RCU should always be the last softirq */ HRTIMER_SOFTIRQ,
RCU_SOFTIRQ, /* Preferable RCU should always be the last softirq */
NR_SOFTIRQS NR_SOFTIRQS
}; };

142
kernel/hrtimer.c
View file

@ -634,7 +634,6 @@ static inline void hrtimer_init_timer_hres(struct hrtimer *timer)
{ {
} }
static void __run_hrtimer(struct hrtimer *timer);
/* /*
* When High resolution timers are active, try to reprogram. Note, that in case * When High resolution timers are active, try to reprogram. Note, that in case
@ -646,13 +645,9 @@ static inline int hrtimer_enqueue_reprogram(struct hrtimer *timer,
struct hrtimer_clock_base *base) struct hrtimer_clock_base *base)
{ {
if (base->cpu_base->hres_active && hrtimer_reprogram(timer, base)) { if (base->cpu_base->hres_active && hrtimer_reprogram(timer, base)) {
/* spin_unlock(&base->cpu_base->lock);
* XXX: recursion check? raise_softirq_irqoff(HRTIMER_SOFTIRQ);
* hrtimer_forward() should round up with timer granularity spin_lock(&base->cpu_base->lock);
* so that we never get into inf recursion here,
* it doesn't do that though
*/
__run_hrtimer(timer);
return 1; return 1;
} }
return 0; return 0;
@ -705,11 +700,6 @@ static inline int hrtimer_enqueue_reprogram(struct hrtimer *timer,
} }
static inline void hrtimer_init_hres(struct hrtimer_cpu_base *base) { } static inline void hrtimer_init_hres(struct hrtimer_cpu_base *base) { }
static inline void hrtimer_init_timer_hres(struct hrtimer *timer) { } 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 */ #endif /* CONFIG_HIGH_RES_TIMERS */
@ -780,9 +770,11 @@ EXPORT_SYMBOL_GPL(hrtimer_forward);
* *
* The timer is inserted in expiry order. Insertion into the * The timer is inserted in expiry order. Insertion into the
* red black tree is O(log(n)). Must hold the base lock. * 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, static int enqueue_hrtimer(struct hrtimer *timer,
struct hrtimer_clock_base *base, int reprogram) struct hrtimer_clock_base *base)
{ {
struct rb_node **link = &base->active.rb_node; struct rb_node **link = &base->active.rb_node;
struct rb_node *parent = NULL; struct rb_node *parent = NULL;
@ -814,20 +806,8 @@ static void enqueue_hrtimer(struct hrtimer *timer,
* Insert the timer to the rbtree and check whether it * Insert the timer to the rbtree and check whether it
* replaces the first pending timer * replaces the first pending timer
*/ */
if (leftmost) { 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; base->first = &timer->node;
}
rb_link_node(&timer->node, parent, link); rb_link_node(&timer->node, parent, link);
rb_insert_color(&timer->node, &base->active); rb_insert_color(&timer->node, &base->active);
@ -836,6 +816,8 @@ static void enqueue_hrtimer(struct hrtimer *timer,
* state of a possibly running callback. * state of a possibly running callback.
*/ */
timer->state |= HRTIMER_STATE_ENQUEUED; timer->state |= HRTIMER_STATE_ENQUEUED;
return leftmost;
} }
/* /*
@ -912,7 +894,7 @@ hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim, unsigned long delta_n
{ {
struct hrtimer_clock_base *base, *new_base; struct hrtimer_clock_base *base, *new_base;
unsigned long flags; unsigned long flags;
int ret; int ret, leftmost;
base = lock_hrtimer_base(timer, &flags); base = lock_hrtimer_base(timer, &flags);
@ -940,12 +922,16 @@ hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim, unsigned long delta_n
timer_stats_hrtimer_set_start_info(timer); timer_stats_hrtimer_set_start_info(timer);
leftmost = enqueue_hrtimer(timer, new_base);
/* /*
* Only allow reprogramming if the new base is on this CPU. * Only allow reprogramming if the new base is on this CPU.
* (it might still be on another CPU if the timer was pending) * (it might still be on another CPU if the timer was pending)
*
* XXX send_remote_softirq() ?
*/ */
enqueue_hrtimer(timer, new_base, if (leftmost && new_base->cpu_base == &__get_cpu_var(hrtimer_bases))
new_base->cpu_base == &__get_cpu_var(hrtimer_bases)); hrtimer_enqueue_reprogram(timer, new_base);
unlock_hrtimer_base(timer, &flags); unlock_hrtimer_base(timer, &flags);
@ -1157,13 +1143,13 @@ static void __run_hrtimer(struct hrtimer *timer)
spin_lock(&cpu_base->lock); spin_lock(&cpu_base->lock);
/* /*
* Note: We clear the CALLBACK bit after enqueue_hrtimer to avoid * Note: We clear the CALLBACK bit after enqueue_hrtimer and
* reprogramming of the event hardware. This happens at the end of this * we do not reprogramm the event hardware. Happens either in
* function anyway. * hrtimer_start_range_ns() or in hrtimer_interrupt()
*/ */
if (restart != HRTIMER_NORESTART) { if (restart != HRTIMER_NORESTART) {
BUG_ON(timer->state != HRTIMER_STATE_CALLBACK); BUG_ON(timer->state != HRTIMER_STATE_CALLBACK);
enqueue_hrtimer(timer, base, 0); enqueue_hrtimer(timer, base);
} }
timer->state &= ~HRTIMER_STATE_CALLBACK; timer->state &= ~HRTIMER_STATE_CALLBACK;
} }
@ -1243,6 +1229,22 @@ void hrtimer_interrupt(struct clock_event_device *dev)
} }
} }
/*
* 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 -- run soft-expired timers now
* *
@ -1254,20 +1256,23 @@ void hrtimer_interrupt(struct clock_event_device *dev)
*/ */
void hrtimer_peek_ahead_timers(void) void hrtimer_peek_ahead_timers(void)
{ {
struct tick_device *td;
unsigned long flags; unsigned long flags;
if (!hrtimer_hres_active())
return;
local_irq_save(flags); local_irq_save(flags);
td = &__get_cpu_var(tick_cpu_device); __hrtimer_peek_ahead_timers();
if (td && td->evtdev)
hrtimer_interrupt(td->evtdev);
local_irq_restore(flags); local_irq_restore(flags);
} }
#endif /* CONFIG_HIGH_RES_TIMERS */ 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: * Called from timer softirq every jiffy, expire hrtimers:
@ -1513,39 +1518,36 @@ static void migrate_hrtimer_list(struct hrtimer_clock_base *old_base,
__remove_hrtimer(timer, old_base, HRTIMER_STATE_MIGRATE, 0); __remove_hrtimer(timer, old_base, HRTIMER_STATE_MIGRATE, 0);
timer->base = new_base; timer->base = new_base;
/* /*
* Enqueue the timers on the new cpu, but do not reprogram * Enqueue the timers on the new cpu. This does not
* the timer as that would enable a deadlock between * reprogram the event device in case the timer
* hrtimer_enqueue_reprogramm() running the timer and us still * expires before the earliest on this CPU, but we run
* holding a nested base lock. * hrtimer_interrupt after we migrated everything to
* * sort out already expired timers and reprogram the
* Instead we tickle the hrtimer interrupt after the migration * event device.
* is done, which will run all expired timers and re-programm
* the timer device.
*/ */
enqueue_hrtimer(timer, new_base, 0); enqueue_hrtimer(timer, new_base);
/* Clear the migration state bit */ /* Clear the migration state bit */
timer->state &= ~HRTIMER_STATE_MIGRATE; timer->state &= ~HRTIMER_STATE_MIGRATE;
} }
} }
static int migrate_hrtimers(int scpu) static void migrate_hrtimers(int scpu)
{ {
struct hrtimer_cpu_base *old_base, *new_base; struct hrtimer_cpu_base *old_base, *new_base;
int dcpu, i; int i;
BUG_ON(cpu_online(scpu)); BUG_ON(cpu_online(scpu));
old_base = &per_cpu(hrtimer_bases, scpu);
new_base = &get_cpu_var(hrtimer_bases);
dcpu = smp_processor_id();
tick_cancel_sched_timer(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 * The caller is globally serialized and nobody else
* takes two locks at once, deadlock is not possible. * takes two locks at once, deadlock is not possible.
*/ */
spin_lock_irq(&new_base->lock); spin_lock(&new_base->lock);
spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING); spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);
for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) { for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
@ -1554,15 +1556,11 @@ static int migrate_hrtimers(int scpu)
} }
spin_unlock(&old_base->lock); spin_unlock(&old_base->lock);
spin_unlock_irq(&new_base->lock); spin_unlock(&new_base->lock);
put_cpu_var(hrtimer_bases);
return dcpu; /* Check, if we got expired work to do */
} __hrtimer_peek_ahead_timers();
local_irq_enable();
static void tickle_timers(void *arg)
{
hrtimer_peek_ahead_timers();
} }
#endif /* CONFIG_HOTPLUG_CPU */ #endif /* CONFIG_HOTPLUG_CPU */
@ -1583,11 +1581,8 @@ static int __cpuinit hrtimer_cpu_notify(struct notifier_block *self,
case CPU_DEAD: case CPU_DEAD:
case CPU_DEAD_FROZEN: case CPU_DEAD_FROZEN:
{ {
int dcpu;
clockevents_notify(CLOCK_EVT_NOTIFY_CPU_DEAD, &scpu); clockevents_notify(CLOCK_EVT_NOTIFY_CPU_DEAD, &scpu);
dcpu = migrate_hrtimers(scpu); migrate_hrtimers(scpu);
smp_call_function_single(dcpu, tickle_timers, NULL, 0);
break; break;
} }
#endif #endif
@ -1608,6 +1603,9 @@ void __init hrtimers_init(void)
hrtimer_cpu_notify(&hrtimers_nb, (unsigned long)CPU_UP_PREPARE, hrtimer_cpu_notify(&hrtimers_nb, (unsigned long)CPU_UP_PREPARE,
(void *)(long)smp_processor_id()); (void *)(long)smp_processor_id());
register_cpu_notifier(&hrtimers_nb); register_cpu_notifier(&hrtimers_nb);
#ifdef CONFIG_HIGH_RES_TIMERS
open_softirq(HRTIMER_SOFTIRQ, run_hrtimer_softirq);
#endif
} }
/** /**