linux-kernel - [PATCH -tip] x86: do_IRQ - send EOI for x86-32 on irq without handler v3

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Date:	Wed, 8 Apr 2009 23:36:56 +0400
From:	Cyrill Gorcunov <gorcunov@...nvz.org>
To:	Ingo Molnar <mingo@...e.hu>, "H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Yinghai Lu <yhlu.kernel@...il.com>
Subject: [PATCH -tip] x86: do_IRQ - send EOI for x86-32 on irq without
	handler v3

For X86-32 if IRQ has no handler it remains non-Ack'ed
even if APIC is not requested for being disabled.

Since disable_apic depends on CONFIG_X86_LOCAL_APIC rather
then CONFIG_X86_64 we could bring tiny fix here.

Signed-off-by: Cyrill Gorcunov <gorcunov@...nvz.org>
---
 arch/x86/kernel/irq.c |   10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

Ingo it's an interim fix.

I didn't manage yet to implement what you proposed
(marked http://lkml.org/lkml/2009/4/8/549).

Index: linux-2.6.git/arch/x86/kernel/irq.c
=====================================================================
--- linux-2.6.git.orig/arch/x86/kernel/irq.c
+++ linux-2.6.git/arch/x86/kernel/irq.c
@@ -223,10 +223,16 @@ unsigned int __irq_entry do_IRQ(struct p
 	irq = __get_cpu_var(vector_irq)[vector];
 
 	if (!handle_irq(irq, regs)) {
-#ifdef CONFIG_X86_64
+		/*
+		 * FIXME: Actually we could go further and replace
+		 * ack_APIC_irq->apic_write->apic->write with a NOP
+		 * operation as only disable_apic is set and happily call
+		 * ack_APIC_irq after that without any tests
+		 */
+#ifdef CONFIG_X86_LOCAL_APIC
 		if (!disable_apic)
-			ack_APIC_irq();
 #endif
+			ack_APIC_irq();
 
 		if (printk_ratelimit())
 			printk(KERN_EMERG "%s: %d.%d No irq handler for vector (irq %d)\n",
--
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