[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));
}
/*