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 [<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. [ Folded in pointer fix from Sudeep ] Reported-by: NAndriy Gapon <avg@FreeBSD.org> Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Cc: Sudeep Holla <sudeep.holla@arm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com> Link: http://lkml.kernel.org/r/20150705205221.802094647@linutronix.de
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