Fix IO-APIC edge IRQ handling. IRQ_INPROGRESS was cleared spuriously

if a new edge happened while we were still processing the previous
one.

Then, if a _third_ edge came in, it would actually cause a reentrant
irq handler invocation, because the original INPROGRESS bit was now
lost.

This was actually seen on IDE in PIO mode.

diff --git a/arch/i386/kernel/irq.c b/arch/i386/kernel/irq.c
index b283b5c0c8b1a798baeceb7e724330cc29073dff..ac767766b6d79f942d86cb32b2cd7653c0c2bb61 100644 (file)
--- a/arch/i386/kernel/irq.c
+++ b/arch/i386/kernel/irq.c
@@ -380,8 +380,9 @@ asmlinkage unsigned int do_IRQ(struct pt_regs regs)
                        break;
                desc->status &= ~IRQ_PENDING;
        }
-out:
        desc->status &= ~IRQ_INPROGRESS;
+
+out:
        /*
         * The ->end() handler has to deal with interrupts which got
         * disabled while the handler was running.
@@ -768,7 +769,7 @@ int setup_irq(unsigned int irq, struct irqaction * new)
 
        if (!shared) {
                desc->depth = 0;
-               desc->status &= ~(IRQ_DISABLED | IRQ_AUTODETECT | IRQ_WAITING);
+               desc->status &= ~(IRQ_DISABLED | IRQ_AUTODETECT | IRQ_WAITING | IRQ_INPROGRESS);
                desc->handler->startup(irq);
        }
        spin_unlock_irqrestore(&desc->lock,flags);