From dffe2e1e1a1ddb566a76266136c312801c66dcf7 Mon Sep 17 00:00:00 2001 From: Jeremy Fitzhardinge Date: Fri, 20 Aug 2010 19:10:01 -0700 Subject: xen: handle events as edge-triggered From: Jeremy Fitzhardinge commit dffe2e1e1a1ddb566a76266136c312801c66dcf7 upstream. Xen events are logically edge triggered, as Xen only calls the event upcall when an event is newly set, but not continuously as it remains set. As a result, use handle_edge_irq rather than handle_level_irq. This has the important side-effect of fixing a long-standing bug of events getting lost if: - an event's interrupt handler is running - the event is migrated to a different vcpu - the event is re-triggered The most noticable symptom of these lost events is occasional lockups of blkfront. Many thanks to Tom Kopec and Daniel Stodden in tracking this down. Signed-off-by: Jeremy Fitzhardinge Cc: Tom Kopec Cc: Daniel Stodden Signed-off-by: Greg Kroah-Hartman --- drivers/xen/events.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/xen/events.c +++ b/drivers/xen/events.c @@ -363,7 +363,7 @@ int bind_evtchn_to_irq(unsigned int evtc irq = find_unbound_irq(); set_irq_chip_and_handler_name(irq, &xen_dynamic_chip, - handle_level_irq, "event"); + handle_edge_irq, "event"); evtchn_to_irq[evtchn] = irq; irq_info[irq] = mk_evtchn_info(evtchn);