irq: replace loop with nr_irqs with for_each_irq_desc

There are a handful of loops that go from 0 to nr_irqs and use
get_irq_desc() on them. These would allocate all the irq_desc
entries, regardless of the need for them.

Use the smarter for_each_irq_desc() iterator that will only iterate
over the present ones.

v2: make sure arch without GENERIC_HARDIRQS work too

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

1 files changed, 2 insertions, 3 deletions

diff --git a/arch/x86/kernel/irq_64.c b/arch/x86/kernel/irq_64.c
index 4a0a4eb44dcb..b3cf55e325f5 100644
--- a/arch/x86/kernel/irq_64.c
+++ b/arch/x86/kernel/irq_64.c
@@ -224,17 +224,16 @@ void fixup_irqs(cpumask_t map)
 {
         unsigned int irq;
         static int warned;
+        struct irq_desc *desc;
 
-        for (irq = 0; irq < nr_irqs; irq++) {
+        for_each_irq_desc(irq, desc) {
                 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(&desc->lock);