From c4288334818c81c946acb23d2319881f58c3d497 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Sun, 5 Jul 2015 20:53:17 +0000 Subject: [PATCH] tick/broadcast: Handle spurious interrupts gracefully Andriy reported that on a virtual machine the warning about negative expiry time in the clock events programming code triggered: hpet: hpet0 irq 40 for MSI hpet: hpet1 irq 41 for MSI Switching to clocksource hpet WARNING: at kernel/time/clockevents.c:239 [] clockevents_program_event+0xdb/0xf0 [] tick_handle_periodic_broadcast+0x41/0x50 [] timer_interrupt+0x15/0x20 When the second hpet is installed as a per cpu timer the broadcast event is not longer required and stopped, which sets the next_evt of the broadcast device to KTIME_MAX. If after that a spurious interrupt happens on the broadcast device, then the current code blindly handles it and tries to reprogram the broadcast device afterwards, which adds the period to next_evt. KTIME_MAX + period results in a negative expiry value causing the WARN_ON in the clockevents code to trigger. Add a proper check for the state of the broadcast device into the interrupt handler and return if the interrupt is spurious. [ Folded in pointer fix from Sudeep ] Reported-by: Andriy Gapon Signed-off-by: Thomas Gleixner Cc: Sudeep Holla Cc: Peter Zijlstra Cc: Preeti U Murthy Link: http://lkml.kernel.org/r/20150705205221.802094647@linutronix.de --- kernel/time/tick-broadcast.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c index c8d731ac9563..ee3cf942d6eb 100644 --- a/kernel/time/tick-broadcast.c +++ b/kernel/time/tick-broadcast.c @@ -316,6 +316,13 @@ static void tick_handle_periodic_broadcast(struct clock_event_device *dev) bool bc_local; raw_spin_lock(&tick_broadcast_lock); + + /* Handle spurious interrupts gracefully */ + if (clockevent_state_shutdown(tick_broadcast_device.evtdev)) { + raw_spin_unlock(&tick_broadcast_lock); + return; + } + bc_local = tick_do_periodic_broadcast(); if (clockevent_state_oneshot(dev)) { -- 2.20.1