generic: sparse irqs: use irq_desc() together with dyn_array, instead of irq_desc[]

add CONFIG_HAVE_SPARSE_IRQ to for use condensed array.
Get rid of irq_desc[] array assumptions.

Preallocate 32 irq_desc, and irq_desc() will try to get more.

( No change in functionality is expected anywhere, except the odd build
  failure where we missed a code site or where a crossing commit itroduces
  new irq_desc[] usage. )

v2: according to Eric, change get_irq_desc() to irq_desc()

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 19 insertions, 16 deletions

diff --git a/arch/x86/kernel/irq_64.c b/arch/x86/kernel/irq_64.c
index e1f0839430d2..738eb65a924e 100644
--- a/arch/x86/kernel/irq_64.c
+++ b/arch/x86/kernel/irq_64.c
@@ -83,15 +83,16 @@ int show_interrupts(struct seq_file *p, void *v)
 
 	if (i < nr_irqs) {
 		unsigned any_count = 0;
+		struct irq_desc *desc = irq_to_desc(i);
 
-		spin_lock_irqsave(&irq_desc[i].lock, flags);
+		spin_lock_irqsave(&desc->lock, flags);
 #ifndef CONFIG_SMP
 		any_count = kstat_irqs(i);
 #else
 		for_each_online_cpu(j)
 			any_count |= kstat_cpu(j).irqs[i];
 #endif
-		action = irq_desc[i].action;
+		action = desc->action;
 		if (!action && !any_count)
 			goto skip;
 		seq_printf(p, "%3d: ",i);
@@ -101,8 +102,8 @@ int show_interrupts(struct seq_file *p, void *v)
 		for_each_online_cpu(j)
 			seq_printf(p, "%10u ", kstat_cpu(j).irqs[i]);
 #endif
-		seq_printf(p, " %8s", irq_desc[i].chip->name);
-		seq_printf(p, "-%-8s", irq_desc[i].name);
+		seq_printf(p, " %8s", desc->chip->name);
+		seq_printf(p, "-%-8s", desc->name);
 
 		if (action) {
 			seq_printf(p, "  %s", action->name);
@@ -111,7 +112,7 @@ int show_interrupts(struct seq_file *p, void *v)
 		}
 		seq_putc(p, '\n');
 skip:
-		spin_unlock_irqrestore(&irq_desc[i].lock, flags);
+		spin_unlock_irqrestore(&desc->lock, flags);
 	} else if (i == nr_irqs) {
 		seq_printf(p, "NMI: ");
 		for_each_online_cpu(j)
@@ -228,37 +229,39 @@ void fixup_irqs(cpumask_t map)
 		cpumask_t mask;
 		int break_affinity = 0;
 		int set_affinity = 1;
+		struct irq_desc *desc;
 
 		if (irq == 2)
 			continue;
 
+		desc = irq_to_desc(irq);
 		/* interrupt's are disabled at this point */
-		spin_lock(&irq_desc[irq].lock);
+		spin_lock(&desc->lock);
 
 		if (!irq_has_action(irq) ||
-		    cpus_equal(irq_desc[irq].affinity, map)) {
-			spin_unlock(&irq_desc[irq].lock);
+		    cpus_equal(desc->affinity, map)) {
+			spin_unlock(&desc->lock);
 			continue;
 		}
 
-		cpus_and(mask, irq_desc[irq].affinity, map);
+		cpus_and(mask, desc->affinity, map);
 		if (cpus_empty(mask)) {
 			break_affinity = 1;
 			mask = map;
 		}
 
-		if (irq_desc[irq].chip->mask)
-			irq_desc[irq].chip->mask(irq);
+		if (desc->chip->mask)
+			desc->chip->mask(irq);
 
-		if (irq_desc[irq].chip->set_affinity)
-			irq_desc[irq].chip->set_affinity(irq, mask);
+		if (desc->chip->set_affinity)
+			desc->chip->set_affinity(irq, mask);
 		else if (!(warned++))
 			set_affinity = 0;
 
-		if (irq_desc[irq].chip->unmask)
-			irq_desc[irq].chip->unmask(irq);
+		if (desc->chip->unmask)
+			desc->chip->unmask(irq);
 
-		spin_unlock(&irq_desc[irq].lock);
+		spin_unlock(&desc->lock);
 
 		if (break_affinity && set_affinity)
 			printk("Broke affinity for irq %i\n", irq);