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, 34 insertions, 12 deletions

diff --git a/arch/x86/kernel/io_apic_32.c b/arch/x86/kernel/io_apic_32.c
index 7f2bcc3dad82..c2160cfdec9b 100644
--- a/arch/x86/kernel/io_apic_32.c
+++ b/arch/x86/kernel/io_apic_32.c
@@ -345,6 +345,7 @@ static void set_ioapic_affinity_irq(unsigned int irq, cpumask_t cpumask)
         struct irq_pin_list *entry = irq_2_pin + irq;
         unsigned int apicid_value;
         cpumask_t tmp;
+        struct irq_desc *desc;
 
         cpus_and(tmp, cpumask, cpu_online_map);
         if (cpus_empty(tmp))
@@ -365,7 +366,8 @@ static void set_ioapic_affinity_irq(unsigned int irq, cpumask_t cpumask)
                         break;
                 entry = irq_2_pin + entry->next;
         }
-        irq_desc[irq].affinity = cpumask;
+        desc = irq_to_desc(irq);
+        desc->affinity = cpumask;
         spin_unlock_irqrestore(&ioapic_lock, flags);
 }
 
@@ -475,10 +477,12 @@ static inline void balance_irq(int cpu, int irq)
 static inline void rotate_irqs_among_cpus(unsigned long useful_load_threshold)
 {
         int i, j;
+        struct irq_desc *desc;
 
         for_each_online_cpu(i) {
                 for (j = 0; j < nr_irqs; j++) {
-                        if (!irq_desc[j].action)
+                        desc = irq_to_desc(j);
+                        if (!desc->action)
                                 continue;
                         /* Is it a significant load ?  */
                         if (IRQ_DELTA(CPU_TO_PACKAGEINDEX(i), j) <
@@ -505,6 +509,7 @@ static void do_irq_balance(void)
         unsigned long tmp_cpu_irq;
         unsigned long imbalance = 0;
         cpumask_t allowed_mask, target_cpu_mask, tmp;
+        struct irq_desc *desc;
 
         for_each_possible_cpu(i) {
                 int package_index;
@@ -515,7 +520,8 @@ static void do_irq_balance(void)
                 for (j = 0; j < nr_irqs; j++) {
                         unsigned long value_now, delta;
                         /* Is this an active IRQ or balancing disabled ? */
-                        if (!irq_desc[j].action || irq_balancing_disabled(j))
+                        desc = irq_to_desc(j);
+                        if (!desc->action || irq_balancing_disabled(j))
                                 continue;
                         if (package_index == i)
                                 IRQ_DELTA(package_index, j) = 0;
@@ -609,7 +615,8 @@ tryanotherirq:
         selected_irq = -1;
         for (j = 0; j < nr_irqs; j++) {
                 /* Is this an active IRQ? */
-                if (!irq_desc[j].action)
+                desc = irq_to_desc(j);
+                if (!desc->action)
                         continue;
                 if (imbalance <= IRQ_DELTA(max_loaded, j))
                         continue;
@@ -682,10 +689,12 @@ static int balanced_irq(void *unused)
         int i;
         unsigned long prev_balance_time = jiffies;
         long time_remaining = balanced_irq_interval;
+        struct irq_desc *desc;
 
         /* push everything to CPU 0 to give us a starting point.  */
         for (i = 0 ; i < nr_irqs ; i++) {
-                irq_desc[i].pending_mask = cpumask_of_cpu(0);
+                desc = irq_to_desc(i);
+                desc->pending_mask = cpumask_of_cpu(0);
                 set_pending_irq(i, cpumask_of_cpu(0));
         }
 
@@ -1254,13 +1263,16 @@ static struct irq_chip ioapic_chip;
 
 static void ioapic_register_intr(int irq, int vector, unsigned long trigger)
 {
+        struct irq_desc *desc;
+
+        desc = irq_to_desc(irq);
         if ((trigger == IOAPIC_AUTO && IO_APIC_irq_trigger(irq)) ||
             trigger == IOAPIC_LEVEL) {
-                irq_desc[irq].status |= IRQ_LEVEL;
+                desc->status |= IRQ_LEVEL;
                 set_irq_chip_and_handler_name(irq, &ioapic_chip,
                                          handle_fasteoi_irq, "fasteoi");
         } else {
-                irq_desc[irq].status &= ~IRQ_LEVEL;
+                desc->status &= ~IRQ_LEVEL;
                 set_irq_chip_and_handler_name(irq, &ioapic_chip,
                                          handle_edge_irq, "edge");
         }
@@ -2027,6 +2039,7 @@ static struct irq_chip ioapic_chip __read_mostly = {
 static inline void init_IO_APIC_traps(void)
 {
         int irq;
+        struct irq_desc *desc;
 
         /*
          * NOTE! The local APIC isn't very good at handling
@@ -2048,9 +2061,11 @@ static inline void init_IO_APIC_traps(void)
                          */
                         if (irq < 16)
                                 make_8259A_irq(irq);
-                        else
+                        else {
+                                desc = irq_to_desc(irq);
                                 /* Strange. Oh, well.. */
-                                irq_desc[irq].chip = &no_irq_chip;
+                                desc->chip = &no_irq_chip;
+                        }
                 }
         }
 }
@@ -2089,7 +2104,10 @@ static struct irq_chip lapic_chip __read_mostly = {
 
 static void lapic_register_intr(int irq, int vector)
 {
-        irq_desc[irq].status &= ~IRQ_LEVEL;
+        struct irq_desc *desc;
+
+        desc = irq_to_desc(irq);
+        desc->status &= ~IRQ_LEVEL;
         set_irq_chip_and_handler_name(irq, &lapic_chip, handle_edge_irq,
                                       "edge");
         set_intr_gate(vector, interrupt[irq]);
@@ -2556,6 +2574,7 @@ static void set_msi_irq_affinity(unsigned int irq, cpumask_t mask)
         unsigned int dest;
         cpumask_t tmp;
         int vector;
+        struct irq_desc *desc;
 
         cpus_and(tmp, mask, cpu_online_map);
         if (cpus_empty(tmp))
@@ -2575,7 +2594,8 @@ static void set_msi_irq_affinity(unsigned int irq, cpumask_t mask)
         msg.address_lo |= MSI_ADDR_DEST_ID(dest);
 
         write_msi_msg(irq, &msg);
-        irq_desc[irq].affinity = mask;
+        desc = irq_to_desc(irq);
+        desc->affinity = mask;
 }
 #endif /* CONFIG_SMP */
 
@@ -2649,6 +2669,7 @@ static void set_ht_irq_affinity(unsigned int irq, cpumask_t mask)
 {
         unsigned int dest;
         cpumask_t tmp;
+        struct irq_desc *desc;
 
         cpus_and(tmp, mask, cpu_online_map);
         if (cpus_empty(tmp))
@@ -2659,7 +2680,8 @@ static void set_ht_irq_affinity(unsigned int irq, cpumask_t mask)
         dest = cpu_mask_to_apicid(mask);
 
         target_ht_irq(irq, dest);
-        irq_desc[irq].affinity = mask;
+        desc = irq_to_desc(irq);
+        desc->affinity = mask;
 }
 #endif