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, 3 insertions, 2 deletions

diff --git a/kernel/irq/spurious.c b/kernel/irq/spurious.c
index e26ca1e90c08..b5d906002e1d 100644
--- a/kernel/irq/spurious.c
+++ b/kernel/irq/spurious.c
@@ -92,11 +92,12 @@ static int misrouted_irq(int irq)
         int ok = 0;
 
         for (i = 1; i < nr_irqs; i++) {
-                struct irq_desc *desc = irq_desc + i;
+                struct irq_desc *desc;
 
                 if (i == irq)   /* Already tried */
                         continue;
 
+                desc = irq_to_desc(i);
                 if (try_one_irq(i, desc))
                         ok = 1;
         }
@@ -108,7 +109,7 @@ static void poll_spurious_irqs(unsigned long dummy)
 {
         int i;
         for (i = 1; i < nr_irqs; i++) {
-                struct irq_desc *desc = irq_desc + i;
+                struct irq_desc *desc = irq_to_desc(i);
                 unsigned int status;
 
                 /* Racy but it doesn't matter */