sparseirq: Use radix_tree instead of ptrs array

Use radix_tree irq_desc_tree instead of irq_desc_ptrs.

-v2: according to Eric and cyrill to use radix_tree_lookup_slot and
     radix_tree_replace_slot

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <1265793639-15071-32-git-send-email-yinghai@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

1 files changed, 25 insertions, 24 deletions

diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c
index 266f7986aa08..76d5a671bfe1 100644
--- a/kernel/irq/handle.c
+++ b/kernel/irq/handle.c
@@ -19,6 +19,7 @@
 #include <linux/kernel_stat.h>
 #include <linux/rculist.h>
 #include <linux/hash.h>
+#include <linux/radix-tree.h>
 #include <trace/events/irq.h>
 
 #include "internals.h"
@@ -127,7 +128,26 @@ static void init_one_irq_desc(int irq, struct irq_desc *desc, int node)
  */
 DEFINE_RAW_SPINLOCK(sparse_irq_lock);
 
-static struct irq_desc **irq_desc_ptrs __read_mostly;
+static RADIX_TREE(irq_desc_tree, GFP_ATOMIC);
+
+static void set_irq_desc(unsigned int irq, struct irq_desc *desc)
+{
+        radix_tree_insert(&irq_desc_tree, irq, desc);
+}
+
+struct irq_desc *irq_to_desc(unsigned int irq)
+{
+        return radix_tree_lookup(&irq_desc_tree, irq);
+}
+
+void replace_irq_desc(unsigned int irq, struct irq_desc *desc)
+{
+        void **ptr;
+
+        ptr = radix_tree_lookup_slot(&irq_desc_tree, irq);
+        if (ptr)
+                radix_tree_replace_slot(ptr, desc);
+}
 
 static struct irq_desc irq_desc_legacy[NR_IRQS_LEGACY] __cacheline_aligned_in_smp = {
         [0 ... NR_IRQS_LEGACY-1] = {
@@ -159,9 +179,6 @@ int __init early_irq_init(void)
         legacy_count = ARRAY_SIZE(irq_desc_legacy);
         node = first_online_node;
 
-        /* allocate irq_desc_ptrs array based on nr_irqs */
-        irq_desc_ptrs = kcalloc(nr_irqs, sizeof(void *), GFP_NOWAIT);
-
         /* allocate based on nr_cpu_ids */
         kstat_irqs_legacy = kzalloc_node(NR_IRQS_LEGACY * nr_cpu_ids *
                                           sizeof(int), GFP_NOWAIT, node);
@@ -175,28 +192,12 @@ int __init early_irq_init(void)
                 lockdep_set_class(&desc[i].lock, &irq_desc_lock_class);
                 alloc_desc_masks(&desc[i], node, true);
                 init_desc_masks(&desc[i]);
-                irq_desc_ptrs[i] = desc + i;
+                set_irq_desc(i, &desc[i]);
         }
 
-        for (i = legacy_count; i < nr_irqs; i++)
-                irq_desc_ptrs[i] = NULL;
-
         return arch_early_irq_init();
 }
 
-struct irq_desc *irq_to_desc(unsigned int irq)
-{
-        if (irq_desc_ptrs && irq < nr_irqs)
-                return irq_desc_ptrs[irq];
-
-        return NULL;
-}
-
-void replace_irq_desc(unsigned int irq, struct irq_desc *desc)
-{
-        irq_desc_ptrs[irq] = desc;
-}
-
 struct irq_desc * __ref irq_to_desc_alloc_node(unsigned int irq, int node)
 {
         struct irq_desc *desc;
@@ -208,14 +209,14 @@ struct irq_desc * __ref irq_to_desc_alloc_node(unsigned int irq, int node)
                 return NULL;
         }
 
-        desc = irq_desc_ptrs[irq];
+        desc = irq_to_desc(irq);
         if (desc)
                 return desc;
 
         raw_spin_lock_irqsave(&sparse_irq_lock, flags);
 
         /* We have to check it to avoid races with another CPU */
-        desc = irq_desc_ptrs[irq];
+        desc = irq_to_desc(irq);
         if (desc)
                 goto out_unlock;
 
@@ -228,7 +229,7 @@ struct irq_desc * __ref irq_to_desc_alloc_node(unsigned int irq, int node)
         }
         init_one_irq_desc(irq, desc, node);
 
-        irq_desc_ptrs[irq] = desc;
+        set_irq_desc(irq, desc);
 
 out_unlock:
         raw_spin_unlock_irqrestore(&sparse_irq_lock, flags);