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, 17 insertions, 13 deletions

diff --git a/arch/x86/kernel/visws_quirks.c b/arch/x86/kernel/visws_quirks.c
index 61a97e616f70..9d85ab384435 100644
--- a/arch/x86/kernel/visws_quirks.c
+++ b/arch/x86/kernel/visws_quirks.c
@@ -484,10 +484,11 @@ static void disable_cobalt_irq(unsigned int irq)
 static unsigned int startup_cobalt_irq(unsigned int irq)
 {
         unsigned long flags;
+        struct irq_desc *desc = irq_to_desc(irq);
 
         spin_lock_irqsave(&cobalt_lock, flags);
-        if ((irq_desc[irq].status & (IRQ_DISABLED | IRQ_INPROGRESS | IRQ_WAITING)))
-                irq_desc[irq].status &= ~(IRQ_DISABLED | IRQ_INPROGRESS | IRQ_WAITING);
+        if ((desc->status & (IRQ_DISABLED | IRQ_INPROGRESS | IRQ_WAITING)))
+                desc->status &= ~(IRQ_DISABLED | IRQ_INPROGRESS | IRQ_WAITING);
         enable_cobalt_irq(irq);
         spin_unlock_irqrestore(&cobalt_lock, flags);
         return 0;
@@ -506,9 +507,10 @@ static void ack_cobalt_irq(unsigned int irq)
 static void end_cobalt_irq(unsigned int irq)
 {
         unsigned long flags;
+        struct irq_desc *desc = irq_to_desc(irq);
 
         spin_lock_irqsave(&cobalt_lock, flags);
-        if (!(irq_desc[irq].status & (IRQ_DISABLED | IRQ_INPROGRESS)))
+        if (!(desc->status & (IRQ_DISABLED | IRQ_INPROGRESS)))
                 enable_cobalt_irq(irq);
         spin_unlock_irqrestore(&cobalt_lock, flags);
 }
@@ -626,7 +628,7 @@ static irqreturn_t piix4_master_intr(int irq, void *dev_id)
 
         spin_unlock_irqrestore(&i8259A_lock, flags);
 
-        desc = irq_desc + realirq;
+        desc = irq_to_desc(realirq);
 
         /*
          * handle this 'virtual interrupt' as a Cobalt one now.
@@ -662,27 +664,29 @@ void init_VISWS_APIC_irqs(void)
         int i;
 
         for (i = 0; i < CO_IRQ_APIC0 + CO_APIC_LAST + 1; i++) {
-                irq_desc[i].status = IRQ_DISABLED;
-                irq_desc[i].action = 0;
-                irq_desc[i].depth = 1;
+                struct irq_desc *desc = irq_to_desc(i);
+
+                desc->status = IRQ_DISABLED;
+                desc->action = 0;
+                desc->depth = 1;
 
                 if (i == 0) {
-                        irq_desc[i].chip = &cobalt_irq_type;
+                        desc->chip = &cobalt_irq_type;
                 }
                 else if (i == CO_IRQ_IDE0) {
-                        irq_desc[i].chip = &cobalt_irq_type;
+                        desc->chip = &cobalt_irq_type;
                 }
                 else if (i == CO_IRQ_IDE1) {
-                        irq_desc[i].chip = &cobalt_irq_type;
+                        desc->chip = &cobalt_irq_type;
                 }
                 else if (i == CO_IRQ_8259) {
-                        irq_desc[i].chip = &piix4_master_irq_type;
+                        desc->chip = &piix4_master_irq_type;
                 }
                 else if (i < CO_IRQ_APIC0) {
-                        irq_desc[i].chip = &piix4_virtual_irq_type;
+                        desc->chip = &piix4_virtual_irq_type;
                 }
                 else if (IS_CO_APIC(i)) {
-                        irq_desc[i].chip = &cobalt_irq_type;
+                        desc->chip = &cobalt_irq_type;
                 }
         }