[PATCH 2/5] genirq: Allocate IRQ descriptors at boot time for !SPARSEIRQ

[Shanker Donthineni]

Remove the use of statically allocated arrays for IRQ descriptors.
Instead, allocate the necessary NR_IRQ descriptors during the boot
time in early_irq_init().

Signed-off-by: Shanker Donthineni <sdonthineni@xxxxxxxxxx>
---
 kernel/irq/irqdesc.c | 21 +++++++++------------
 1 file changed, 9 insertions(+), 12 deletions(-)

diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index 21a968bc468b..a4911f7ebb07 100644
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -556,27 +556,24 @@ int __init early_irq_init(void)
 
 #else /* !CONFIG_SPARSE_IRQ */
 
-struct irq_desc irq_desc[NR_IRQS] __cacheline_aligned_in_smp = {
-	[0 ... NR_IRQS-1] = {
-		.handle_irq	= handle_bad_irq,
-		.depth		= 1,
-		.lock		= __RAW_SPIN_LOCK_UNLOCKED(irq_desc->lock),
-	}
-};
+static struct irq_desc *irq_descs;
 
 int __init early_irq_init(void)
 {
-	int count, i, node = first_online_node;
+	int i, node = first_online_node;
 	struct irq_desc *desc;
 
 	init_irq_default_affinity();
 
 	printk(KERN_INFO "NR_IRQS: %d\n", NR_IRQS);
 
-	desc = irq_desc;
-	count = ARRAY_SIZE(irq_desc);
+	desc = kmalloc_array(NR_IRQS, sizeof(*desc), GFP_KERNEL | __GFP_ZERO);
+	if (desc == NULL)
+		return -ENOMEM;
+
+	irq_descs = desc;
 
-	for (i = 0; i < count; i++) {
+	for (i = 0; i < NR_IRQS; i++) {
 		desc[i].kstat_irqs = alloc_percpu(unsigned int);
 		alloc_masks(&desc[i], node);
 		raw_spin_lock_init(&desc[i].lock);
@@ -593,7 +590,7 @@ int __init early_irq_init(void)
 
 struct irq_desc *irq_to_desc(unsigned int irq)
 {
-	return (irq < NR_IRQS) ? irq_desc + irq : NULL;
+	return (irq < NR_IRQS) ? irq_descs + irq : NULL;
 }
 EXPORT_SYMBOL(irq_to_desc);
 
-- 
2.25.1