Hi,
I've still some doubts about these irq handlers and I hope somebody
could explain some of these (despite my problems with earlier such
explanations, sorry...):
1. According to some well-known Intel's manual (vol.3A page 8-41)
lapic can interrupt irq handler dispatching higher-priority irq; it
seems, such an event is possible during handle_IRQ_event, and would
be treated by "common" handlers with IRQ_INPROGRESS; but:
a) handle_level_irq and handle_edge_irq do unconditional ack-masking
and return; so, I wonder how, after finishing with this current one,
the higher-priority level type and masked irq could find it's way
home/cpu? (edge type would be retriggered, of course)
b) handle_fasteoi_irq acks but doesn't mask, so isn't it possible
this irq would be repeated by ioapic soon, maybe with some looping?
BTW: below is my patch proposal to exclude such thing at least when
IRQ_DISABLED.
2. I wonder, why handle_edge_irq kstat_cpu counter works different
than others (i.e. counts less).
Thanks,
Jarek P.
-------->
Don't let handle_fasteoi_irq() delay irq masking when IRQ_INPROGRESS
&& IRQ_DISABLED.
Signed-off-by: Jarek Poplawski <[EMAIL PROTECTED]>
---
diff -Nurp 2.6.23-rc2-/kernel/irq/chip.c 2.6.23-rc2/kernel/irq/chip.c
--- 2.6.23-rc2-/kernel/irq/chip.c 2007-07-09 01:32:17.000000000 +0200
+++ 2.6.23-rc2/kernel/irq/chip.c 2007-08-21 08:50:36.000000000 +0200
@@ -392,7 +392,8 @@ handle_fasteoi_irq(unsigned int irq, str
spin_lock(&desc->lock);
- if (unlikely(desc->status & IRQ_INPROGRESS))
+ if (unlikely((desc->status & (IRQ_INPROGRESS | IRQ_DISABLED))
+ == IRQ_INPROGRESS))
goto out;
desc->status &= ~(IRQ_REPLAY | IRQ_WAITING);
-
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