The stop/shutdown op should not use decrementer_set_next_event because
that sets decrementers_next_tb to now + decrementer_max, which means a
decrementer interrupt that occurs after that time will call the
clockevent event handler unexpectedly. Set next_tb to ~0 here to prevent
any clock event call. Init all clockevents to stopped.
Then the decrementer clockevent device always has event_handler set and
applicable because we know the clock event device was not stopped. So
make this call unconditional to show that it is always called. next_tb
need not be set to ~0 before the event handler is called because it will
stop the clockevent device if there is no other timer.
Finally, the timer broadcast interrupt should not modify next_tb because
it is not involved with the local decrementer clockevent on this CPU.
This doesn't fix a known bug, just tidies the code.
Signed-off-by: Nicholas Piggin <npig...@gmail.com>
---
arch/powerpc/kernel/time.c | 18 ++++++++++--------
1 file changed, 10 insertions(+), 8 deletions(-)
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index 384f58a3f373..f3845601ab6a 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -107,7 +107,12 @@ struct clock_event_device decrementer_clockevent = {
};
EXPORT_SYMBOL(decrementer_clockevent);
-DEFINE_PER_CPU(u64, decrementers_next_tb);
+/*
+ * This always puts next_tb beyond now, so the clock event will never fire
+ * with the usual comparison, no need for a separate test for stopped.
+ */
+#define DEC_CLOCKEVENT_STOPPED ~0ULL
+DEFINE_PER_CPU(u64, decrementers_next_tb) = DEC_CLOCKEVENT_STOPPED;
EXPORT_SYMBOL_GPL(decrementers_next_tb);
static DEFINE_PER_CPU(struct clock_event_device, decrementers);
@@ -644,9 +649,7 @@ DEFINE_INTERRUPT_HANDLER_ASYNC(timer_interrupt)
now = get_tb();
if (now >= *next_tb) {
- *next_tb = ~(u64)0;
- if (evt->event_handler)
- evt->event_handler(evt);
+ evt->event_handler(evt);
__this_cpu_inc(irq_stat.timer_irqs_event);
} else {
now = *next_tb - now;
@@ -665,9 +668,6 @@ EXPORT_SYMBOL(timer_interrupt);
#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
void timer_broadcast_interrupt(void)
{
- u64 *next_tb = this_cpu_ptr(&decrementers_next_tb);
-
- *next_tb = ~(u64)0;
tick_receive_broadcast();
__this_cpu_inc(irq_stat.broadcast_irqs_event);
}
@@ -893,7 +893,9 @@ static int decrementer_set_next_event(unsigned long evt,
static int decrementer_shutdown(struct clock_event_device *dev)
{
- decrementer_set_next_event(decrementer_max, dev);
+ __this_cpu_write(decrementers_next_tb, DEC_CLOCKEVENT_STOPPED);
+ set_dec_or_work(decrementer_max);
+
return 0;
}
--
2.23.0
