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Commit b6ecfa92 authored by Jan Glauber's avatar Jan Glauber Committed by Martin Schwidefsky
Browse files

[S390] extend virtual timer interface by mod_virt_timer_periodic 



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: default avatarJan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 04362301

arch/s390/include/asm/timer.h

+1 −0
Original line number Diff line number Diff line
@@ -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);

arch/s390/kernel/vtime.c

+33 −24
Original line number Diff line number Diff line
@@ -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;
@@ -444,27 +434,22 @@ 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 */



		if (periodic)

			timer->interval = expires;

		else

			timer->interval = 0;

		timer->expires = expires;

		timer->cpu = cpu;
@@ -472,11 +457,12 @@ int mod_virt_timer(struct vtimer_list *timer, __u64 expires) 
		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

 *