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);