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