[PATCH] s390: idle timer setup
Fix overflow in calculation of the new tod value in stop_hz_timer and fix
wrong virtual timer list idle time in case the virtual timer is already
expired in stop_cpu_timer.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c
index 061e811..8ca4856 100644
--- a/arch/s390/kernel/time.c
+++ b/arch/s390/kernel/time.c
@@ -244,7 +244,7 @@
*/
static inline void stop_hz_timer(void)
{
- __u64 timer;
+ __u64 timer, todval;
if (sysctl_hz_timer != 0)
return;
@@ -265,8 +265,14 @@
* for the next event.
*/
timer = (__u64) (next_timer_interrupt() - jiffies) + jiffies_64;
- timer = jiffies_timer_cc + timer * CLK_TICKS_PER_JIFFY;
- asm volatile ("SCKC %0" : : "m" (timer));
+ todval = -1ULL;
+ /* Be careful about overflows. */
+ if (timer < (-1ULL / CLK_TICKS_PER_JIFFY)) {
+ timer = jiffies_timer_cc + timer * CLK_TICKS_PER_JIFFY;
+ if (timer >= jiffies_timer_cc)
+ todval = timer;
+ }
+ asm volatile ("SCKC %0" : : "m" (todval));
}
/*
diff --git a/arch/s390/kernel/vtime.c b/arch/s390/kernel/vtime.c
index bb6cf02..fa07265 100644
--- a/arch/s390/kernel/vtime.c
+++ b/arch/s390/kernel/vtime.c
@@ -122,12 +122,17 @@
struct vtimer_queue *vt_list;
vt_list = &per_cpu(virt_cpu_timer, smp_processor_id());
- set_vtimer(vt_list->idle);
+
+ /* CPU timer interrupt is pending, don't reprogramm it */
+ if (vt_list->idle & 1LL<<63)
+ return;
+
+ if (!list_empty(&vt_list->list))
+ set_vtimer(vt_list->idle);
}
static void stop_cpu_timer(void)
{
- __u64 done;
struct vtimer_queue *vt_list;
vt_list = &per_cpu(virt_cpu_timer, smp_processor_id());
@@ -138,21 +143,17 @@
goto fire;
}
- /* store progress */
- asm volatile ("STPT %0" : "=m" (done));
+ /* store the actual expire value */
+ asm volatile ("STPT %0" : "=m" (vt_list->idle));
/*
- * If done is negative we do not stop the CPU timer
- * because we will get instantly an interrupt that
- * will start the CPU timer again.
+ * If the CPU timer is negative we don't reprogramm
+ * it because we will get instantly an interrupt.
*/
- if (done & 1LL<<63)
+ if (vt_list->idle & 1LL<<63)
return;
- else
- vt_list->offset += vt_list->to_expire - done;
- /* save the actual expire value */
- vt_list->idle = done;
+ vt_list->offset += vt_list->to_expire - vt_list->idle;
/*
* We cannot halt the CPU timer, we just write a value that