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hrtimer: fixup the HRTIMER_CB_IRQSAFE_NO_SOFTIRQ fallback

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Currently all highres=off timers are run from softirq context, but
HRTIMER_CB_IRQSAFE_NO_SOFTIRQ timers expect to run from irq context.

Fix this up by splitting it similar to the highres=on case.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2008-01-25 21:08:31 +01:00 committed by Ingo Molnar
parent 2d44ae4d71
commit d3d74453c3
3 changed files with 189 additions and 181 deletions
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5
include/linux/hrtimer.h
View File

@ -115,10 +115,8 @@ struct hrtimer {
enum hrtimer_restart (*function)(struct hrtimer *);
struct hrtimer_clock_base *base;
unsigned long state;
#ifdef CONFIG_HIGH_RES_TIMERS
enum hrtimer_cb_mode cb_mode;
struct list_head cb_entry;
#endif
#ifdef CONFIG_TIMER_STATS
void *start_site;
char start_comm[16];
@ -194,10 +192,10 @@ struct hrtimer_cpu_base {
spinlock_t lock;
struct lock_class_key lock_key;
struct hrtimer_clock_base clock_base[HRTIMER_MAX_CLOCK_BASES];
struct list_head cb_pending;
#ifdef CONFIG_HIGH_RES_TIMERS
ktime_t expires_next;
int hres_active;
struct list_head cb_pending;
unsigned long nr_events;
#endif
};
@ -319,6 +317,7 @@ extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
/* Soft interrupt function to run the hrtimer queues: */
extern void hrtimer_run_queues(void);
extern void hrtimer_run_pending(void);
/* Bootup initialization: */
extern void __init hrtimers_init(void);

362
kernel/hrtimer.c
View File

@ -325,6 +325,22 @@ unsigned long ktime_divns(const ktime_t kt, s64 div)
}
#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
@ -493,22 +509,6 @@ void hres_timers_resume(void)
retrigger_next_event(NULL);
}
/*
* 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);
}
/*
* Initialize the high resolution related parts of cpu_base
*/
@ -516,7 +516,6 @@ static inline void hrtimer_init_hres(struct hrtimer_cpu_base *base)
{
base->expires_next.tv64 = KTIME_MAX;
base->hres_active = 0;
INIT_LIST_HEAD(&base->cb_pending);
}
/*
@ -524,7 +523,6 @@ static inline void hrtimer_init_hres(struct hrtimer_cpu_base *base)
*/
static inline void hrtimer_init_timer_hres(struct hrtimer *timer)
{
INIT_LIST_HEAD(&timer->cb_entry);
}
/*
@ -618,10 +616,13 @@ static inline int hrtimer_enqueue_reprogram(struct hrtimer *timer,
{
return 0;
}
static inline int hrtimer_cb_pending(struct hrtimer *timer) { return 0; }
static inline void hrtimer_remove_cb_pending(struct hrtimer *timer) { }
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 */
@ -1001,6 +1002,7 @@ void hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
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
@ -1030,118 +1032,8 @@ int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp)
}
EXPORT_SYMBOL_GPL(hrtimer_get_res);
#ifdef CONFIG_HIGH_RES_TIMERS
/*
* High resolution timer interrupt
* Called with interrupts disabled
*/
void hrtimer_interrupt(struct clock_event_device *dev)
static void run_hrtimer_pending(struct hrtimer_cpu_base *cpu_base)
{
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)) {
enum hrtimer_restart (*fn)(struct hrtimer *);
struct hrtimer *timer;
int restart;
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;
}
__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;
}
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)
{
struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
spin_lock_irq(&cpu_base->lock);
while (!list_empty(&cpu_base->cb_pending)) {
@ -1182,56 +1074,126 @@ static void run_hrtimer_softirq(struct softirq_action *h)
spin_unlock_irq(&cpu_base->lock);
}
#endif /* CONFIG_HIGH_RES_TIMERS */
/*
* Expire the per base hrtimer-queue:
*/
static inline void run_hrtimer_queue(struct hrtimer_cpu_base *cpu_base,
int index)
static void __run_hrtimer(struct hrtimer *timer)
{
struct rb_node *node;
struct hrtimer_clock_base *base = &cpu_base->clock_base[index];
struct hrtimer_clock_base *base = timer->base;
struct hrtimer_cpu_base *cpu_base = base->cpu_base;
enum hrtimer_restart (*fn)(struct hrtimer *);
int restart;
if (!base->first)
return;
if (base->get_softirq_time)
base->softirq_time = base->get_softirq_time();
spin_lock_irq(&cpu_base->lock);
while ((node = base->first)) {
struct hrtimer *timer;
enum hrtimer_restart (*fn)(struct hrtimer *);
int restart;
timer = rb_entry(node, struct hrtimer, node);
if (base->softirq_time.tv64 <= timer->expires.tv64)
break;
#ifdef CONFIG_HIGH_RES_TIMERS
WARN_ON_ONCE(timer->cb_mode == HRTIMER_CB_IRQSAFE_NO_SOFTIRQ);
#endif
timer_stats_account_hrtimer(timer);
fn = timer->function;
__remove_hrtimer(timer, base, HRTIMER_STATE_CALLBACK, 0);
spin_unlock_irq(&cpu_base->lock);
__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);
spin_lock_irq(&cpu_base->lock);
timer->state &= ~HRTIMER_STATE_CALLBACK;
if (restart != HRTIMER_NORESTART) {
BUG_ON(hrtimer_active(timer));
enqueue_hrtimer(timer, base, 0);
}
/*
* 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);
}
spin_unlock_irq(&cpu_base->lock);
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:
*
@ -1239,10 +1201,9 @@ static inline void run_hrtimer_queue(struct hrtimer_cpu_base *cpu_base,
* softirq context in case the hrtimer initialization failed or has
* not been done yet.
*/
void hrtimer_run_queues(void)
void hrtimer_run_pending(void)
{
struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
int i;
if (hrtimer_hres_active())
return;
@ -1256,8 +1217,54 @@ void hrtimer_run_queues(void)
* deadlock vs. xtime_lock.
*/
if (tick_check_oneshot_change(!hrtimer_is_hres_enabled()))
if (hrtimer_switch_to_hres())
return;
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);
@ -1407,6 +1414,7 @@ static void __cpuinit init_hrtimers_cpu(int cpu)
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);
}

3
kernel/timer.c
View File

@ -896,7 +896,7 @@ static void run_timer_softirq(struct softirq_action *h)
{
tvec_base_t *base = __get_cpu_var(tvec_bases);
hrtimer_run_queues();
hrtimer_run_pending();
if (time_after_eq(jiffies, base->timer_jiffies))
__run_timers(base);
@ -907,6 +907,7 @@ static void run_timer_softirq(struct softirq_action *h)
*/
void run_local_timers(void)
{
hrtimer_run_queues();
raise_softirq(TIMER_SOFTIRQ);
softlockup_tick();
}