Subject: Re: [PATCH] 2.6.18-rt7: PowerPC: fix breakage in threaded fasteoi type IRQ handlers

From: Ingo Molnar <[email-masked]>
Date: Mon, 20 Nov 2006 20:10:13 +0100

* Sergei Shtylyov <[email-masked]> wrote:

> >-#else
> >-		set_irq_chip_and_handler_name(irq, &ioapic_chip,
> >-					      handle_edge_irq, "edge");
> >-#endif
> >+					 handle_edge_irq, "edge");
> 
>    Hm, why force edge flow on edge-triggered IRQs?

it doesnt do that. This, ontop of -rt4 restores it to the vanilla arch 
code.

> > 	if (desc->chip->mask_ack)
> > 		desc->chip->mask_ack(irq);
> > 	else {
> >-		desc->chip->mask(irq);
> >-		desc->chip->ack(irq);
> >+		if (desc->chip->mask)
> >+			desc->chip->mask(irq);
> >+		if (desc->chip->mask)
> >+			desc->chip->ack(irq);
> > 	}
> > }
> 
>    Hmm, that just won't do for PPC threaded fasteoi flows! What you'll 
> get is a threaded IRQ with EOI *never ever* issued, unless my PPC 
> patch is also in...

ok, how about the patch below in addition?

	Ingo

Index: linux/kernel/irq/chip.c
===================================================================
--- linux.orig/kernel/irq/chip.c
+++ linux/kernel/irq/chip.c
@@ -396,7 +398,7 @@ handle_fasteoi_irq(unsigned int irq, str
 	 */
 	if (redirect_hardirq(desc)) {
 		mask_ack_irq(desc, irq);
-		goto out_unlock;
+		goto out;
 	}
 
 	desc->status &= ~IRQ_PENDING;