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[ARM] Fix Neponset IRQ handling

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While testing the genirq code on ARM, a condition was found whereby
the Neponset IRQ handler was being re-entered, causing the system
to deadlock.

Under the ARM IRQ code, this would not have been a visible problem
because the "simple" IRQ handling had no re-entrancy protection.

Resolve this by acknowledging the parent interrupt after we mask it
when we are going to handle one of our "special" level-based sources
(from ethernet or USAR chip.)

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Russell King 2006-06-08 17:59:31 +01:00 committed by Russell King
parent 1def630a6a
commit d782f33df7
1 changed files with 8 additions and 0 deletions
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8
arch/arm/mach-sa1100/neponset.c
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@ -59,6 +59,14 @@ neponset_irq_handler(unsigned int irq, struct irqdesc *desc, struct pt_regs *reg
if (irr & (IRR_ETHERNET | IRR_USAR)) { if (irr & (IRR_ETHERNET | IRR_USAR)) {
desc->chip->mask(irq); desc->chip->mask(irq);
/*
* Ack the interrupt now to prevent re-entering
* this neponset handler. Again, this is safe
* since we'll check the IRR register prior to
* leaving.
*/
desc->chip->ack(irq);
if (irr & IRR_ETHERNET) { if (irr & IRR_ETHERNET) {
d = irq_desc + IRQ_NEPONSET_SMC9196; d = irq_desc + IRQ_NEPONSET_SMC9196;
desc_handle_irq(IRQ_NEPONSET_SMC9196, d, regs); desc_handle_irq(IRQ_NEPONSET_SMC9196, d, regs);