On Mon, 6 Jul 2015, Sudeep Holla wrote: > On Sun, Jul 5, 2015 at 9:53 PM, Thomas Gleixner <[email protected]> wrote: > > 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 > > > > [<ffffffff810ce6eb>] clockevents_program_event+0xdb/0xf0 > > [<ffffffff810cf211>] tick_handle_periodic_broadcast+0x41/0x50 > > [<ffffffff81016525>] 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. > > > > Reported-by: Andriy Gapon <[email protected]> > > Signed-off-by: Thomas Gleixner <[email protected]> > > --- > > kernel/time/tick-broadcast.c | 7 +++++++ > > 1 file changed, 7 insertions(+) > > > > Index: tip/kernel/time/tick-broadcast.c > > =================================================================== > > --- tip.orig/kernel/time/tick-broadcast.c > > +++ tip/kernel/time/tick-broadcast.c > > @@ -301,6 +301,13 @@ static void tick_handle_periodic_broadca > > bool bc_local; > > > > raw_spin_lock(&tick_broadcast_lock); > > + > > + /* Handle spurious interrupts gracefully */ > > + if (clockevent_state_shutdown(&tick_broadcast_device.evtdev)) { > > I tried this patch along with 1/2, found that this generating warning as > tick_broadcast_device.evtdev is of type ‘struct clock_event_device *’ already, > so it can be passed directly.
Right you are. The heat is melting my brain ...
