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[S390] extend virtual timer interface by mod_virt_timer_periodic

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In case mod_virt_timer is used to add a non pending timer the timer
is always added as a one-shot timer. If mod_virt_timer is used for
periodic timers they may therfore be degraded to one-shot timers.

Add mod_virt_timer_periodic to the interface to allow safe re-programming
of the interval value.

Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Jan Glauber 2009-04-14 15:36:20 +02:00 committed by Martin Schwidefsky
parent 0436230148
commit b6ecfa9273
2 changed files with 34 additions and 24 deletions
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1
arch/s390/include/asm/timer.h
View File

@ -41,6 +41,7 @@ extern void init_virt_timer(struct vtimer_list *timer);
extern void add_virt_timer(void *new);
extern void add_virt_timer_periodic(void *new);
extern int mod_virt_timer(struct vtimer_list *timer, __u64 expires);
extern int mod_virt_timer_periodic(struct vtimer_list *timer, __u64 expires);
extern int del_virt_timer(struct vtimer_list *timer);
extern void init_cpu_vtimer(void);

57
arch/s390/kernel/vtime.c
View File

@ -425,17 +425,7 @@ void add_virt_timer_periodic(void *new)
}
EXPORT_SYMBOL(add_virt_timer_periodic);
/*
* If we change a pending timer the function must be called on the CPU
* where the timer is running on, e.g. by smp_call_function_single()
*
* The original mod_timer adds the timer if it is not pending. For
* compatibility we do the same. The timer will be added on the current
* CPU as a oneshot timer.
*
* returns whether it has modified a pending timer (1) or not (0)
*/
int mod_virt_timer(struct vtimer_list *timer, __u64 expires)
int __mod_vtimer(struct vtimer_list *timer, __u64 expires, int periodic)
{
struct vtimer_queue *vq;
unsigned long flags;
@ -444,39 +434,35 @@ int mod_virt_timer(struct vtimer_list *timer, __u64 expires)
BUG_ON(!timer->function);
BUG_ON(!expires || expires > VTIMER_MAX_SLICE);
/*
* This is a common optimization triggered by the
* networking code - if the timer is re-modified
* to be the same thing then just return:
*/
if (timer->expires == expires && vtimer_pending(timer))
return 1;
cpu = get_cpu();
vq = &per_cpu(virt_cpu_timer, cpu);
/* check if we run on the right CPU */
BUG_ON(timer->cpu != cpu);
/* disable interrupts before test if timer is pending */
spin_lock_irqsave(&vq->lock, flags);
/* if timer isn't pending add it on the current CPU */
if (!vtimer_pending(timer)) {
spin_unlock_irqrestore(&vq->lock, flags);
/* we do not activate an interval timer with mod_virt_timer */
timer->interval = 0;
if (periodic)
timer->interval = expires;
else
timer->interval = 0;
timer->expires = expires;
timer->cpu = cpu;
internal_add_vtimer(timer);
return 0;
}
/* check if we run on the right CPU */
BUG_ON(timer->cpu != cpu);
list_del_init(&timer->entry);
timer->expires = expires;
/* also change the interval if we have an interval timer */
if (timer->interval)
if (periodic)
timer->interval = expires;
/* the timer can't expire anymore so we can release the lock */
@ -484,8 +470,31 @@ int mod_virt_timer(struct vtimer_list *timer, __u64 expires)
internal_add_vtimer(timer);
return 1;
}
/*
* If we change a pending timer the function must be called on the CPU
* where the timer is running on.
*
* returns whether it has modified a pending timer (1) or not (0)
*/
int mod_virt_timer(struct vtimer_list *timer, __u64 expires)
{
return __mod_vtimer(timer, expires, 0);
}
EXPORT_SYMBOL(mod_virt_timer);
/*
* If we change a pending timer the function must be called on the CPU
* where the timer is running on.
*
* returns whether it has modified a pending timer (1) or not (0)
*/
int mod_virt_timer_periodic(struct vtimer_list *timer, __u64 expires)
{
return __mod_vtimer(timer, expires, 1);
}
EXPORT_SYMBOL(mod_virt_timer_periodic);
/*
* delete a virtual timer
*