[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: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diff --git a/arch/s390/include/asm/timer.h b/arch/s390/include/asm/timer.h
index e4bcab7..814243c 100644 (file)
--- a/arch/s390/include/asm/timer.h
+++ b/arch/s390/include/asm/timer.h
@@ -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);

diff --git a/arch/s390/kernel/vtime.c b/arch/s390/kernel/vtime.c
index ecf0304..694b443 100644 (file)
--- a/arch/s390/kernel/vtime.c
+++ b/arch/s390/kernel/vtime.c
@@ -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
  *