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[PATCH] fix next_timer_interrupt() for hrtimer 

Also from Thomas Gleixner <tglx@linutronix.de>

Function next_timer_interrupt() got broken with a recent patch
6ba1b91213 as sys_nanosleep() was moved to
hrtimer.  This broke things as next_timer_interrupt() did not check hrtimer
tree for next event.

Function next_timer_interrupt() is needed with dyntick (CONFIG_NO_IDLE_HZ,
VST) implementations, as the system can be in idle when next hrtimer event
was supposed to happen.  At least ARM and S390 currently use
next_timer_interrupt().

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Tony Lindgren 2006-03-06 15:42:45 -08:00 committed by Linus Torvalds
parent f7c09bd972
commit 69239749e1
4 changed files with 61 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
arch/arm/kernel/time.c
View File

@ -422,12 +422,14 @@ static int timer_dyn_tick_disable(void)
void timer_dyn_reprogram(void)
{
struct dyn_tick_timer *dyn_tick = system_timer->dyn_tick;
unsigned long next, seq;
if (dyn_tick) {
write_seqlock(&xtime_lock);
if (dyn_tick->state & DYN_TICK_ENABLED)
if (dyn_tick && (dyn_tick->state & DYN_TICK_ENABLED)) {
next = next_timer_interrupt();
do {
seq = read_seqbegin(&xtime_lock);
dyn_tick->reprogram(next_timer_interrupt() - jiffies);
write_sequnlock(&xtime_lock);
} while (read_seqretry(&xtime_lock, seq));
}
}

4
include/linux/hrtimer.h
View File

@ -116,6 +116,10 @@ extern int hrtimer_try_to_cancel(struct hrtimer *timer);
extern ktime_t hrtimer_get_remaining(const struct hrtimer *timer);
extern int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp);
#ifdef CONFIG_NO_IDLE_HZ
extern ktime_t hrtimer_get_next_event(void);
#endif
static inline int hrtimer_active(const struct hrtimer *timer)
{
return timer->state == HRTIMER_PENDING;

35
kernel/hrtimer.c
View File

@ -505,6 +505,41 @@ ktime_t hrtimer_get_remaining(const struct hrtimer *timer)
return rem;
}
#ifdef CONFIG_NO_IDLE_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_base *base = __get_cpu_var(hrtimer_bases);
ktime_t delta, mindelta = { .tv64 = KTIME_MAX };
unsigned long flags;
int i;
for (i = 0; i < MAX_HRTIMER_BASES; i++, base++) {
struct hrtimer *timer;
spin_lock_irqsave(&base->lock, flags);
if (!base->first) {
spin_unlock_irqrestore(&base->lock, flags);
continue;
}
timer = rb_entry(base->first, struct hrtimer, node);
delta.tv64 = timer->expires.tv64;
spin_unlock_irqrestore(&base->lock, flags);
delta = ktime_sub(delta, base->get_time());
if (delta.tv64 < mindelta.tv64)
mindelta.tv64 = delta.tv64;
}
if (mindelta.tv64 < 0)
mindelta.tv64 = 0;
return mindelta;
}
#endif
/**
* hrtimer_init - initialize a timer to the given clock
*

16
kernel/timer.c
View File

@ -489,9 +489,21 @@ unsigned long next_timer_interrupt(void)
struct list_head *list;
struct timer_list *nte;
unsigned long expires;
unsigned long hr_expires = MAX_JIFFY_OFFSET;
ktime_t hr_delta;
tvec_t *varray[4];
int i, j;
hr_delta = hrtimer_get_next_event();
if (hr_delta.tv64 != KTIME_MAX) {
struct timespec tsdelta;
tsdelta = ktime_to_timespec(hr_delta);
hr_expires = timespec_to_jiffies(&tsdelta);
if (hr_expires < 3)
return hr_expires + jiffies;
}
hr_expires += jiffies;
base = &__get_cpu_var(tvec_bases);
spin_lock(&base->t_base.lock);
expires = base->timer_jiffies + (LONG_MAX >> 1);
@ -542,6 +554,10 @@ found:
}
}
spin_unlock(&base->t_base.lock);
if (time_before(hr_expires, expires))
return hr_expires;
return expires;
}
#endif