x86_64: rename irq_desc/irq_desc_alloc

change names:

          irq_desc() ==> irq_desc_alloc
	__irq_desc() ==> irq_desc

Also split a few of the uses in lowlevel x86 code.

v2: need to check if desc is null in smp_irq_move_cleanup

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/kernel/io_apic_64.c b/arch/x86/kernel/io_apic_64.c
index 1b8cccb..a054db9 100644
--- a/arch/x86/kernel/io_apic_64.c
+++ b/arch/x86/kernel/io_apic_64.c
@@ -1124,7 +1124,12 @@
 {
 	struct irq_desc *desc;
 
-	desc = irq_to_desc(irq);
+	/* first time to use this irq_desc */
+	if (irq < 16)
+		desc = irq_to_desc(irq);
+	else
+		desc = irq_to_desc_alloc(irq);
+
 	if (trigger)
 		desc->status |= IRQ_LEVEL;
 	else
@@ -1919,6 +1924,9 @@
 		irq = __get_cpu_var(vector_irq)[vector];
 
 		desc = irq_to_desc(irq);
+		if (!desc)
+			continue;
+
 		cfg = irq_cfg(irq);
 		spin_lock(&desc->lock);
 		if (!cfg->move_cleanup_count)
diff --git a/arch/x86/kernel/irq_64.c b/arch/x86/kernel/irq_64.c
index f337f87..5d5976e 100644
--- a/arch/x86/kernel/irq_64.c
+++ b/arch/x86/kernel/irq_64.c
@@ -83,7 +83,7 @@
 
 	if (i < nr_irqs) {
 		unsigned any_count = 0;
-		struct irq_desc *desc = __irq_to_desc(i);
+		struct irq_desc *desc = irq_to_desc(i);
 
 		if (!desc)
 			return 0;
@@ -206,7 +206,7 @@
 	stack_overflow_check(regs);
 #endif
 
-	desc = __irq_to_desc(irq);
+	desc = irq_to_desc(irq);
 	if (likely(desc))
 		generic_handle_irq_desc(irq, desc);
 	else {
diff --git a/arch/x86/kernel/irqinit_64.c b/arch/x86/kernel/irqinit_64.c
index cd9f42d..d17fbc2 100644
--- a/arch/x86/kernel/irqinit_64.c
+++ b/arch/x86/kernel/irqinit_64.c
@@ -143,7 +143,8 @@
 	init_8259A(0);
 
 	for (i = 0; i < 16; i++) {
-		struct irq_desc *desc = irq_to_desc(i);
+		/* first time call this irq_desc */
+		struct irq_desc *desc = irq_to_desc_alloc(i);
 
 		desc->status = IRQ_DISABLED;
 		desc->action = NULL;