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Subject[patch 40/71] clockevents: prevent endless loop in periodic broadcast handler
2.6.26-stable review patch.  If anyone has any objections, please let us
know.

------------------
From: Thomas Gleixner <tglx@linutronix.de>
commit d4496b39559c6d43f83e4c08b899984f8b8089b5 upstream

The reprogramming of the periodic broadcast handler was broken,
when the first programming returned -ETIME. The clockevents code
stores the new expiry value in the clock events device next_event field
only when the programming time has not been elapsed yet. The loop in
question calculates the new expiry value from the next_event value
and therefor never increases.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
kernel/time/tick-broadcast.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c
@@ -174,6 +174,8 @@ static void tick_do_periodic_broadcast(v
*/
static void tick_handle_periodic_broadcast(struct clock_event_device *dev)
{
+ ktime_t next;
+
tick_do_periodic_broadcast();

/*
@@ -184,10 +186,13 @@ static void tick_handle_periodic_broadca

/*
* Setup the next period for devices, which do not have
- * periodic mode:
+ * periodic mode. We read dev->next_event first and add to it
+ * when the event alrady expired. clockevents_program_event()
+ * sets dev->next_event only when the event is really
+ * programmed to the device.
*/
- for (;;) {
- ktime_t next = ktime_add(dev->next_event, tick_period);
+ for (next = dev->next_event; ;) {
+ next = ktime_add(next, tick_period);

if (!clockevents_program_event(dev, next, ktime_get()))
return;
--


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