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, 14 insertions, 10 deletions

diff --git a/arch/x86/kernel/irq_32.c b/arch/x86/kernel/irq_32.c
index 4c7ffb32854c..ede513be517d 100644
--- a/arch/x86/kernel/irq_32.c
+++ b/arch/x86/kernel/irq_32.c
@@ -224,7 +224,7 @@ unsigned int do_IRQ(struct pt_regs *regs)
         struct pt_regs *old_regs;
         /* high bit used in ret_from_ code */
         int overflow, irq = ~regs->orig_ax;
-        struct irq_desc *desc = irq_desc + irq;
+        struct irq_desc *desc = irq_to_desc(irq);
 
         if (unlikely((unsigned)irq >= nr_irqs)) {
                 printk(KERN_EMERG "%s: cannot handle IRQ %d\n",
@@ -273,15 +273,16 @@ 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);
@@ -291,8 +292,8 @@ 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);
@@ -302,7 +303,7 @@ 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)
@@ -398,17 +399,20 @@ void fixup_irqs(cpumask_t map)
 
         for (irq = 0; irq < nr_irqs; irq++) {
                 cpumask_t mask;
+                struct irq_desc *desc;
+
                 if (irq == 2)
                         continue;
 
-                cpus_and(mask, irq_desc[irq].affinity, map);
+                desc = irq_to_desc(irq);
+                cpus_and(mask, desc->affinity, map);
                 if (any_online_cpu(mask) == NR_CPUS) {
                         printk("Breaking affinity for irq %i\n", irq);
                         mask = map;
                 }
-                if (irq_desc[irq].chip->set_affinity)
-                        irq_desc[irq].chip->set_affinity(irq, mask);
-                else if (irq_desc[irq].action && !(warned++))
+                if (desc->chip->set_affinity)
+                        desc->chip->set_affinity(irq, mask);
+                else if (desc->action && !(warned++))
                         printk("Cannot set affinity for irq %i\n", irq);
         }