[PATCH] genirq: x86_64 irq: Reenable migrating irqs to other cpus

In the latest changes the code for migrating x86_64 irqs was dropped.  This
reads it in a fashion that will work even if we change the vector on level
triggered irqs when we migrate them.

[akpm@osdl.org: build fix]
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Rajesh Shah <rajesh.shah@intel.com>
Cc: Andi Kleen <ak@muc.de>
Cc: "Protasevich, Natalie" <Natalie.Protasevich@UNISYS.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/x86_64/kernel/io_apic.c

@@ -1254,18 +1254,48 @@ static int ioapic_retrigger_vector(unsigned int vector)
  * races.
  */
 
-static void ack_apic(unsigned int vector)
+static void ack_apic(unsigned int irq)
 {
 	ack_APIC_irq();
 }
 
+static void ack_apic_edge(unsigned int irq)
+{
+	move_native_irq(irq);
+	ack_APIC_irq();
+}
+
+static void ack_apic_level(unsigned int irq)
+{
+	int do_unmask_irq = 0;
+
+#if defined(CONFIG_GENERIC_PENDING_IRQ) || defined(CONFIG_IRQBALANCE)
+	/* If we are moving the irq we need to mask it */
+	if (unlikely(irq_desc[irq].status & IRQ_MOVE_PENDING)) {
+		do_unmask_irq = 1;
+		mask_IO_APIC_irq(irq);
+	}
+#endif
+
+	/*
+	 * We must acknowledge the irq before we move it or the acknowledge will
+	 * not propogate properly.
+	 */
+	ack_APIC_irq();
+
+	/* Now we can move and renable the irq */
+	move_masked_irq(irq);
+	if (unlikely(do_unmask_irq))
+		unmask_IO_APIC_irq(irq);
+}
+
 static struct irq_chip ioapic_chip __read_mostly = {
 	.name 		= "IO-APIC",
 	.startup 	= startup_ioapic_vector,
 	.mask	 	= mask_ioapic_vector,
 	.unmask	 	= unmask_ioapic_vector,
-	.ack 		= ack_apic,
-	.eoi 		= ack_apic,
+	.ack 		= ack_apic_edge,
+	.eoi 		= ack_apic_level,
 #ifdef CONFIG_SMP
 	.set_affinity 	= set_ioapic_affinity_vector,
 #endif