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, 5 insertions, 3 deletions

diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index ed8235187dc0..56ace47f24d6 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -125,7 +125,7 @@ static void bind_evtchn_to_cpu(unsigned int chn, unsigned int cpu)
 
         BUG_ON(irq == -1);
 #ifdef CONFIG_SMP
-        irq_desc[irq].affinity = cpumask_of_cpu(cpu);
+        irq_to_desc(irq)->affinity = cpumask_of_cpu(cpu);
 #endif
 
         __clear_bit(chn, cpu_evtchn_mask[cpu_evtchn[chn]]);
@@ -139,8 +139,10 @@ static void init_evtchn_cpu_bindings(void)
 #ifdef CONFIG_SMP
         int i;
         /* By default all event channels notify CPU#0. */
-        for (i = 0; i < nr_irqs; i++)
-                irq_desc[i].affinity = cpumask_of_cpu(0);
+        for (i = 0; i < nr_irqs; i++) {
+                struct irq_desc *desc = irq_to_desc(i);
+                desc->affinity = cpumask_of_cpu(0);
+        }
 #endif
 
         memset(cpu_evtchn, 0, sizeof(cpu_evtchn));