From 37fb9a0231ee43d42d069863bdfd567fca2b61af Mon Sep 17 00:00:00 2001 From: Anton Blanchard Date: Wed, 23 Nov 2011 20:07:17 +0000 Subject: powerpc/time: Handle wrapping of decrementer When re-enabling interrupts we have code to handle edge sensitive decrementers by resetting the decrementer to 1 whenever it is negative. If interrupts were disabled long enough that the decrementer wrapped to positive we do nothing. This means interrupts can be delayed for a long time until it finally goes negative again. While we hope interrupts are never be disabled long enough for the decrementer to go positive, we have a very good test team that can drive any kernel into the ground. The softlockup data we get back from these fails could be seconds in the future, completely missing the cause of the lockup. We already keep track of the timebase of the next event so use that to work out if we should trigger a decrementer exception. Signed-off-by: Anton Blanchard Cc: stable@kernel.org Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/kernel/time.c | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'arch/powerpc/kernel/time.c') diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c index 522bb1dfc353..5db163c96751 100644 --- a/arch/powerpc/kernel/time.c +++ b/arch/powerpc/kernel/time.c @@ -889,6 +889,15 @@ static void __init clocksource_init(void) clock->name, clock->mult, clock->shift); } +void decrementer_check_overflow(void) +{ + u64 now = get_tb_or_rtc(); + struct decrementer_clock *decrementer = &__get_cpu_var(decrementers); + + if (now >= decrementer->next_tb) + set_dec(1); +} + static int decrementer_set_next_event(unsigned long evt, struct clock_event_device *dev) { -- cgit v1.2.3