| From | Paul Gortmaker <> | Subject | [34-longterm 030/260] xen: handle events as edge-triggered | Date | Sun, 2 Jan 2011 02:15:26 -0500 |
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From: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
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 <jeremy.fitzhardinge@citrix.com> Cc: Tom Kopec <tek@acm.org> Cc: Daniel Stodden <daniel.stodden@citrix.com> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> --- drivers/xen/events.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/drivers/xen/events.c b/drivers/xen/events.c index 28f133a..cc72dad 100644 --- a/drivers/xen/events.c +++ b/drivers/xen/events.c @@ -363,7 +363,7 @@ int bind_evtchn_to_irq(unsigned int evtchn) 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); -- 1.7.3.3
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